Hydrodynamic Gas Bearing and Rotating Machinery

Abstract

The present invention relates to the technical field of gas bearings, and particularly relates to a hydrodynamic gas bearing and a rotating machine. The hydrodynamic gas bearing of the present invention includes a housing, a top foil and a wave foil. The mating unit of the top foil cooperates with the wave unit of the wave foil to form a first cavity, a first gap, a second cavity and a second gap that are continuously distributed along the circumference of the bearing and communicate with each other. Moreover, the flow areas of the first gap and the second gap are smaller than the flow areas of the first cavity and the second cavity, which can reduce the circumferential flow capacity of the gas along the hydrodynamic gas bearing and improve the damping characteristics of the hydrodynamic gas bearing.

Description

Technical Field

[0001] The present invention relates to the technical field of gas bearings, and particularly to a hydrodynamic gas bearing and a rotating machine. Background Art

[0002] Hydrodynamic gas bearings are widely used in rotating machines such as high-speed machine tools, centrifuges, and compressors to meet the higher rotational speed and temperature requirements of rotating machines.

[0003] As a typical structure of a hydrodynamic gas bearing, a hydrodynamic gas bearing includes a housing, a top foil, and a corrugated foil. The top foil is supported on the housing by the elastic corrugated foil and forms a working gap with the rotor. This working gap is a wedge-shaped convergent gap. When the rotor rotates, gas can enter this wedge-shaped convergent gap and is gradually compressed to form a gas film, which plays a supporting role for the rotor. Such a hydrodynamic gas bearing is also called a foil hydrodynamic gas bearing.

[0004] In the above-mentioned foil hydrodynamic gas bearing, the friction between the foils and between the foils and the housing will impose certain restrictive effects on its sliding and generate energy dissipation in the form of heat, thereby generating damping. And damping plays an irreplaceable role in reducing the amplitude of the rotor and improving the rotational accuracy. Therefore, developing a bearing with large damping characteristics is of great significance for improving the stability of the shafting.

[0005] However, in the related art, the damping of the foil hydrodynamic gas bearing still needs to be improved. Summary of the Invention

[0006] One technical problem to be solved by the present invention is to improve the damping of the hydrodynamic gas bearing.

[0007] To solve the above technical problem, the present invention provides a hydrodynamic gas bearing, which includes:

[0008] A housing having a shaft hole for inserting a rotor; and

[0009] A foil unit disposed on the housing and including:

[0010] A top foil for forming a working gap with the rotor; and

[0011] A corrugated foil located between the top foil and the housing and including a corrugated unit. The corrugated unit includes a first part and a second part connected to each other. The first part contacts the inner wall of the housing. The first part is one of a wave valley and a wave peak, and the second part is the other of the wave valley and the wave peak. And the first parts and the second parts of two adjacent corrugated units along the circumferential direction of the shaft hole are connected;

[0012] Among them, the top foil includes a fitting unit. The fitting units correspond one-to-one with the wavy units and each include a first fitting portion and a second fitting portion connected to each other. The first fitting portion and the second fitting portion correspond to the first part and the second part respectively. The first fitting portions of two adjacent fitting units circumferentially adjacent along the axial hole are connected to the second fitting portions, and the first fitting portion protrudes from the second fitting portion towards the first part. There is a first gap between the first fitting portion and the first part, and a second gap between the second fitting portion and the second part. First cavities and second cavities are respectively formed between the first fitting portion and the two second parts adjacent to itself. The flow areas of the first gap and the second gap are both smaller than the flow areas of the first cavities and the second cavities.

[0013] In some embodiments, the first fitting portion includes a first connecting body, a second connecting body, and a third connecting body. The first connecting body is connected to the second fitting portion of an adjacent fitting unit. The second connecting body is connected to the second fitting portion of the same fitting unit corresponding to itself. Both the first connecting body and the second connecting body extend from the second fitting portion they are connected to towards the direction close to the first part. The third connecting body connects the first connecting body and the second connecting body. The first gap is located between the third connecting body and the corresponding first part. The first cavity is located between the first connecting body and the second part adjacent to itself. The second cavity is located between the second connecting body and the second part adjacent to itself.

[0014] In some embodiments, along the direction from the top foil to the housing, the first connecting body and the second connecting body approach each other.

[0015] In some embodiments, the third connecting body is linear, serrated, or arc-shaped.

[0016] In some embodiments, the first fitting portion is trapezoidal or rectangular.

[0017] In some embodiments, the wave trough is linear; and / or, the wave crest is arc-shaped.

[0018] In some embodiments, the first part is a wave trough and the second part is a wave crest.

[0019] In some embodiments, the hydrodynamic gas bearing is an axial hydrodynamic gas bearing. The hydrodynamic gas bearing includes a plurality of foil units arranged circumferentially along the axial hole, and an air inlet channel is provided between adjacent foil units.

[0020] In some embodiments, an internal flow channel is formed between the wave foil, the top foil, and the housing. The hydrodynamic gas bearing further includes a radial flow blocking structure provided on the housing and used to block the connection between the internal flow channel and the outside in the radial direction of the axial hole.

[0021] In some embodiments, the radial flow blocking structure includes a retaining ring unit corresponding to the foil unit, and the retaining ring unit shields at least one of the two openings at both ends of the internal flow passage along the radial direction of the shaft hole.

[0022] In some embodiments, the retaining ring unit includes a retaining ring, the retaining ring is disposed at at least one of the two ends of the foil unit along the radial direction of the shaft hole, and the retaining ring extends axially along the shaft hole by the housing to be flush with or higher than the end of the top foil away from the housing.

[0023] In some embodiments, retaining rings are provided at both ends of the foil unit along the radial direction of the shaft hole.

[0024] In some embodiments, the retaining ring units correspond to the foil units one by one.

[0025] In some embodiments, an air flow preselection structure is provided on the intake passage, and the air flow preselection structure is used to make the air flow have a velocity along the rotation direction of the rotor when flowing into the hydrodynamic gas bearing through the intake passage.

[0026] In some embodiments, the air flow preselection structure includes an inclined groove, the inclined groove is disposed at at least one of the two ends of the intake passage along the radial direction of the shaft hole, and the inclined groove is arranged obliquely with respect to the radial direction of the shaft hole.

[0027] In some embodiments, inclined grooves are provided at both ends of the intake passage along the radial direction of the shaft hole, and the inclination directions of the two inclined grooves on the intake passage are opposite to each other with respect to the radial direction of the shaft hole.

[0028] On the other hand, the present invention also provides a rotating machine, which includes a rotor and the hydrodynamic gas bearing of the present invention, and a working gap is formed between the top foil of the hydrodynamic gas bearing and the rotor.

[0029] In the present invention, the top foil is changed from a flat foil structure to a foil structure with undulations on the surface, which can increase the number of gap seals between the top foil and the wave foil and reduce the circumferential flow capacity of the gas along the hydrodynamic gas bearing. Since this can increase friction, it is beneficial to improve the damping characteristics of the hydrodynamic gas bearing.

[0030] Other features and advantages of the present invention will become clear by the following detailed description of the exemplary embodiments of the present invention with reference to the accompanying drawings. Description of the Drawings

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0032] Figure 1Schematic diagram showing the combined structure of a hydrodynamic gas bearing and a rotor according to an embodiment of the present invention.

[0033] Figure 2 Showing Figure 1 The front view of the combined structure shown in

[0034] Figure 3 Showing Figure 2 The A-A cross-sectional view of

[0035] Figure 4 Showing Figure 3 The enlarged partial view I of

[0036] Figure 5 Showing Figure 1 The three-dimensional structure schematic diagram of the hydrodynamic gas bearing in

[0037] Figure 6 Showing Figure 5 The front view of

[0038] Figure 7 Showing Figure 6 The B-B cross-sectional view of

[0039] Figure 8 Showing Figure 3 The enlarged partial view II of

[0040] Figure 9 Showing Figure 5 The front view after omitting the foil unit

[0041] Figure 10 Showing Figure 9 The left view of

[0042] Figure 11 Showing Figure 9 The enlarged partial view III of

[0043] Figure 12 Showing Figure 9 The enlarged partial view IV of

[0044] Figure 13 Showing Figure 10 The enlarged partial view V of

[0045] In the figure:

[0046] 1. Hydrodynamic gas bearing;

[0047] 11. Housing; 111. Axial hole; 1a. Foil unit; 12. Top foil; 12a. Fitting unit; 121. First fitting portion; 121a. First connecting body; 121b. Second connecting body; 121c. Third connecting body; 122. Second fitting portion; 13. Wave foil; 13a. Wave unit; 131. First part; 132. Second part; 14. Radial flow blocking structure; 14a. Retaining ring unit; 141. Retaining ring; 15. Airflow preselection structure; 151. Inclined groove;

[0048] 2. Rotor;

[0049] 21. Rotating shaft; 22. Thrust disk;

[0050] G1. First gap; G2. Second gap; V1. First cavity; V2. Second cavity; q. Gas; P. Intake passage; F. Internal flow passage; H. Height. Detailed implementation manners

[0051] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and in no way serves as a limitation on the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0052] Technologies, methods and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the said technologies, methods and devices should be regarded as part of the authorization specification.

[0053] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by orientation words such as "front, rear, upper, lower, left, right", "transverse, vertical, perpendicular, horizontal" and "top, bottom" is usually based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and simplifying the description. Without contrary explanation, these orientation words do not indicate and imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and thus cannot be understood as a limitation on the protection scope of the present invention; the orientation words "inside, outside" refer to inside and outside the contour of each component itself.

[0054] In the description of the present invention, it should be understood that using words such as "first", "second" to limit components is only for the convenience of distinguishing the corresponding components. Without otherwise stating, the above words have no special meaning, and thus cannot be understood as a limitation on the protection scope of the present invention.

[0055] In addition, the technical features involved in different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0056] The damping characteristics of the bearing affect the amplitude and rotational accuracy of the rotor. The greater the damping, the more beneficial it is to reduce the amplitude of the rotor and improve the rotational stability of the rotor.

[0057] For a foil journal gas bearing, the friction among the housing, the wave foil, and the top foil is an important factor affecting damping. On the premise that the bearing temperature is stable, the greater the friction, the greater the damping of the bearing.

[0058] However, in the related art, the friction effect of the foil journal gas bearing still needs to be improved.

[0059] According to the different loads borne, the journal gas bearing can be divided into a radial journal gas bearing, an axial gas bearing, etc. Among them, the radial journal gas bearing mainly bears radial loads. The axial journal gas bearing mainly bears axial loads and is also called a journal gas thrust bearing.

[0060] For the convenience of description, the following will focus on taking the axial journal gas bearing as an example for introduction.

[0061] In the related art, the friction characteristics of the axial journal gas bearing have the following two problems:

[0062] (1) There is circumferential flow between the top foil and the wave foil, which affects the friction effect. In the related art, the wave foil adopts a corrugated foil structure, and the top foil generally adopts a flat foil structure, that is, the top foil is a smooth circular arc foil with no undulations on its surface and no convex structure. In this case, the sealing performance between the top foil and the wave foil is poor. When the rotor rotates, the surrounding gas will be driven by the rotor to enter between the top foil and the wave foil and flow circumferentially. Since the flow of the gas will cool the housing, the wave foil, and the top foil of the bearing, and at the same time the gas will play a lubricating role, it affects the friction effect and reduces the friction effect.

[0063] (2) There is radial flow between the wave foil and the housing and the top foil, which affects the friction effect. Between the wave foil with a corrugated structure and the housing and the top foil, internal flow channels are formed. In the related art, these internal flow channels are unobstructed in the radial direction, and gas can flow through these internal flow channels radially, which also affects the friction effect.

[0064] In view of the above problems, the present invention improves the structure of the journal gas bearing to improve the friction effect, increase the damping, and further reduce the amplitude of the rotor and improve the rotational stability of the rotor.

[0065] Figures 1 - 13One of the embodiments is shown. The hydrodynamic gas bearing in this embodiment is an axial hydrodynamic gas bearing. And the arrow in the figure indicates the rotation direction of the rotor.

[0066] Next, in combination with Figures 1 - 13 the present invention will be described.

[0067] As an aspect of the present invention, the present invention chokes the circumferential direction of the hydrodynamic gas bearing to reduce the circumferential flow capacity of the hydrodynamic gas bearing, improve the friction effect, and increase the damping.

[0068] Referring to Figures 1 - 4 , in order to achieve the circumferential choking of the hydrodynamic gas bearing, in the present invention, the hydrodynamic gas bearing 1 includes:

[0069] a housing 11 having a shaft hole 111 for inserting the rotor 2; and

[0070] a foil unit 1a disposed in the housing 11 and including:

[0071] a top foil 12 for forming a working gap with the rotor 2; and

[0072] a wave foil 13 located between the top foil 12 and the housing 11 and including a wave unit 13a. The wave unit 13a includes a first part 131 and a second part 132 connected to each other. The first part 131 contacts the inner wall of the housing 11. The first part 131 is one of a wave valley and a wave peak, and the second part 132 is the other of the wave valley and the wave peak. And the first parts 131 of two adjacent wave units 13a along the circumferential direction of the shaft hole 111 are connected to the second parts 132;

[0073] Wherein, the top foil 12 includes a fitting unit 12a. The fitting unit 12a corresponds to the wave unit 13a one by one and includes a first fitting portion 121 and a second fitting portion 122 connected to each other. The first fitting portion 121 and the second fitting portion 122 correspond to the first part 131 and the second part 132 respectively. The first fitting portions 121 of two adjacent fitting units 12a along the circumferential direction of the shaft hole 111 are connected to the second fitting portions 122. And the first fitting portion 121 protrudes from the second fitting portion 122 towards the first part 131. There is a first gap G1 between the first fitting portion 121 and the first part 131, and a second gap G2 between the second fitting portion 122 and the second part 132. The flow areas of the first gap G1 and the second gap G2 are both smaller than the flow areas of the first cavity V1 and the second cavity V2.

[0074] Based on the set mating unit 12a, the top foil 12 is no longer a flat foil structure with a smooth surface, but becomes a foil structure with undulations on the surface, and a multiple-gap seal is formed with the corrugated foil 13, which can effectively reduce the circumferential flow capacity of gas between the top foil 12 and the corrugated foil 13. Since this can weaken the cooling and lubricating effects of the gas, the friction between the top foil 12 and the corrugated foil 13 can be increased, and the damping characteristics of the hydrodynamic gas bearing 1 can be improved.

[0075] Among them, the multiple sealing gaps between the top foil 12 and the corrugated foil 13 are described with reference to Figure 4 as follows.

[0076] With reference to Figure 4 , in a pair of mating wavy units 13a and mating unit 12a, a first gap G1 is formed between the first mating portion 121 and the first part 131, and a second gap G2 is formed between the second mating portion 122 and the second part 132. And on both circumferential sides of the first gap G1, there are a first cavity V1 and a second cavity V2 respectively, so that between the wavy unit 13a and the mating unit 12a, a first cavity V1, a first gap G1, a second cavity V2 and a second gap G2 that are continuously distributed along the bearing circumference and communicate with each other are formed. And the flow areas of the first gap G1 and the second gap G2 are smaller than the flow areas of the first cavity V1 and the second cavity V2. In this way, when the gas flows circumferentially, every time it passes through a waveform (or a flow section), it can experience two throttling processes, playing a circumferential flow blocking role.

[0077] Specifically, during the working process, the gas q makes a circumferential movement driven by the rotor 2. When the gas q flows from the first cavity V1 into the first gap G1, it is approximately an ideal throttling process, the pressure of the gas q drops, and the velocity increases; next, when flowing from the first gap G1 into the second cavity V2, due to the sudden increase in the flow area, the gas q forms a strong vortex, so that the velocity of the gas q almost completely disappears, and the pressure can be considered to be almost unchanged, that is, equal to the pressure in the first gap G1; then, the gas q flows to the second gap G2 and repeats the throttling process again, so that the pressure of the gas q drops and the velocity increases.

[0078] When the gas q flows through the space between the top foil 12 and the corrugated foil 13 circumferentially, the above process is repeated for each gap and cavity. And the more towards the back, the more the gas q accumulates, the larger the specific volume. When flowing through the small gaps (i.e., the first gap G1 and the second gap G2), the velocity and pressure drop become larger and larger. And as the pressure drop increases, the pressure gradually tends to the back pressure, thus playing a sealing role and effectively reducing the circumferential flow capacity of the bearing.

[0079] As a comparison, in the related art, the top foil 12 is an arc-shaped foil structure with a smooth surface, which does not have a first mating portion 121 protruding towards the first part 131 of the wave foil 13. In this case, there is only a second gap G2 between the top foil 12 and the wave foil 13, but there is no first gap G1, resulting in the inability to form a gap seal between the top foil 12 and the first part 131, and the circumferential flow blocking effect is relatively poor.

[0080] It can be seen that by adding a first mating portion 121 protruding towards the first part 131 of the wave foil 13 on the top foil 12, the present invention forms a relatively effective comb seal between the top foil 12 and the wave foil 13, blocking the circumferential air flow, which is beneficial to enhancing the friction effect between the top foil 12 and the wave foil 13 and improving the damping of the hydrodynamic gas bearing 1.

[0081] Although Figure 4 only the case where the hydrodynamic gas bearing 1 is an axial hydrodynamic gas bearing is shown, in fact, the above circumferential flow blocking technology is also applicable to a radial hydrodynamic gas bearing.

[0082] In addition, in Figure 4 , the first part 131 is a straight wave valley, and at the same time the second part 132 is an arc-shaped wave peak, but this does not constitute the only limitation on the structure of the wave foil 13. For example, the first part 131 and the second part 132 can also be interchanged, that is, the first part 131 is a wave peak and the first part 132 is a wave valley, that is, the wave foil 13 shown in Figure 4 is arranged upside down, or the shapes of the wave valley and the wave peak can also be changed. For example, the wave valley is no longer a straight flat section but also an arc section. In this case, the wave foil 13 is in a sine wave shape.

[0083] Referring to Figure 4 , as an embodiment of the first mating portion 121 of the present invention, the first mating portion 121 may include a first connecting body 121a, a second connecting body 121b, and a third connecting body 121c. The first connecting body 121a is connected to the second mating portion 122 of the adjacent mating unit 12a, the second connecting body 121b is connected to the second mating portion 122 of the same mating unit 12a corresponding to itself, and both the first connecting body 121a and the second connecting body 121b extend from the second mating portion 122 they are connected to towards the direction close to the first part 131. The third connecting body 121c connects the first connecting body 121a and the second connecting body 121b. The first gap G1 is located between the third connecting body 121c and the corresponding first part 131, the first cavity V1 is located between the first connecting body 121a and the adjacent second part 132, and the second cavity V2 is located between the second connecting body 121b and the adjacent second part 132.

[0084] Among them, the shape of the third connecting body 121c is not specifically limited. For example, it can be linear, serrated, or arc-shaped. In some embodiments, the shape of the third connecting body 121c can be adapted to the shape of the first part 131 to achieve a more effective clearance throttling effect. For example, referring to Figure 4 , when the first part 131 is linear, the third connecting body 121c can also be linear. In this way, the third connecting body 121c can better cooperate with the first part 131 to form a first gap G1 that can achieve a more sufficient throttling effect. And as described above, if the first part 131 is arc-shaped, the third connecting body 121c can also be arc-shaped to cooperate with the first part 131 to form a more effective throttling gap.

[0085] In addition, referring to Figure 4 , in some embodiments, along the direction from the top foil 12 to the housing 11, the first connecting body 121a and the second connecting body 121b can approach each other. Based on this, the longitudinal section of the first fitting portion 121 is generally trapezoidal, and along the direction from the housing 11 to the top foil 12, the flow-through areas of the first cavity V1 and the second cavity V2 gradually increase. This is beneficial to achieving a more desirable change in the flow-through area between the first cavity V1 and the first gap G1, between the first gap G1 and the second cavity V2, and between the second cavity V2 and the second gap G2, so as to more effectively play a circumferential flow-blocking role.

[0086] As a variant, the first fitting portion 121 may not be trapezoidal but may have other shapes such as rectangular. Here, the rectangle includes a square.

[0087] In addition, based on the first fitting portion 121 of the foregoing embodiments, the present invention can not only improve the damping through the circumferential sealing effect, but also increase the bearing stiffness and the contact area between the top foil 12 and the wave foil 13 to improve the damping. Because when the deformation amount of the wave foil 13 is relatively large, the first fitting portion 121 of the top foil 12 can contact the wave foil 12 and participate in the deformation. On the one hand, this can provide additional stiffness, and on the other hand, it can also increase the contact area between the top foil 12 and the wave foil 13. According to the principle of damping generation, this can increase the damping of the hydrodynamic gas bearing 1.

[0088] As another aspect of the present invention, the present invention also blocks the flow in the radial direction of the hydrodynamic gas bearing to reduce the radial flow capacity of the hydrodynamic gas bearing, increase the friction effect, and increase the damping.

[0089] Still taking the axial hydrodynamic gas bearing shown in Figures 1 - 13 as an example for illustration.

[0090] Referring to Figures 5 - 13As shown, when the hydrodynamic gas bearing 1 is an axial hydrodynamic gas bearing, it includes a plurality of foil units 1a, and these foil units 1a are arranged along the circumferential direction of the shaft hole 111, and an intake passage P is provided between adjacent foil units 1a. During operation, the rotating rotor 2 drives the surrounding gas to enter the bearing through the intake passage P, and forms a gas film between the top foil 12 and the thrust disk 22 of the rotor 2, playing a supporting role.

[0091] Among them, referring to Figure 8 , an internal flow passage F is formed between the wave foil 12, the top foil 13 and the housing 11, and the internal flow passage F extends along the radial direction of the shaft hole 111.

[0092] In the related art, these internal flow passages F are all unobstructed, resulting in the gas flowing in these internal flow passages F along the radial direction of the shaft hole 111, which also affects the damping magnitude of the hydrodynamic gas bearing 1.

[0093] To solve this problem, referring to Figure 5 , Figure 8 and Figure 13 As shown, in the present invention, the hydrodynamic gas bearing 1 further includes a radial flow blocking structure 14, which is provided on the housing 11 and is used to block the communication between the internal flow passage F and the outside in the radial direction of the shaft hole 111. In this way, the radial flow blocking structure 14 can play a radial flow blocking role, and by preventing the gas from flowing in these internal flow passages F along the radial direction of the shaft hole 111, the radial flow-through capacity of the hydrodynamic gas bearing 1 is reduced, the friction effect is improved, and the damping is increased.

[0094] Among them, the radial flow blocking structure 14 may include, for example, a retaining ring unit 14a corresponding to the foil unit 1a, and the retaining ring unit 14a shields at least one of the two ends of the internal flow passage F along the radial direction of the shaft hole 111. By shielding at least one of the two radial openings of the internal passage F, the retaining ring unit 14a can block the gas from flowing into the internal passage P along the radial direction of the shaft hole 111, thereby reducing the radial flow-through capacity of the hydrodynamic gas bearing 1.

[0095] Specifically, the retaining ring unit 14a may include a retaining ring 141, the retaining ring 141 is disposed at at least one of the two ends of the foil unit 1a along the radial direction of the shaft hole 111, and the retaining ring 141 extends from the housing 11 along the axial direction of the shaft hole 111 to be flush with or higher than the end of the top foil 12 away from the housing 11. Based on this, referring to Figure 8 and Figure 13, the height H of the retaining ring 141 is greater than or equal to the height of the top foil 12, which can shield the radial ports of the internal channel F, prevent gas from flowing back into the internal flow channel F, reduce the flow capacity of gas at the internal channel F, and increase the damping of the hydrodynamic gas bearing 1. Moreover, the height H of the retaining ring 141 being greater than or equal to the height of the top foil 12 can also prevent gas from flowing in from above the top foil 12, which is also beneficial for increasing the damping of the hydrodynamic gas bearing 1.

[0096] Among them, the retaining ring 141 can be provided only at one radial port of the internal channel F. In this case, the retaining ring unit 14a only shields one radial port of the internal channel F. However, more preferably, retaining rings 141 can be provided at both radial ports of the internal channel F, that is, retaining rings 141 are provided at both ends of the foil unit 1a along the radial direction of the shaft hole 111. In this case, the retaining ring unit 14a shields both radial ports of the internal channel F, so that no matter from which end of the internal channel F, gas cannot flow back into the internal channel F, thereby more effectively reducing the radial flow capacity of the hydrodynamic gas bearing 1.

[0097] Refer to Figure 5 , in some embodiments, a single retaining ring 14a can be provided at each foil unit 1a, that is, the retaining ring unit 14a can correspond to the foil unit 1a one by one. In this way, radial flow blocking can be performed on all internal channels P of the hydrodynamic gas bearing 1, more effectively increasing the damping. As a variant, in some other embodiments, the retaining ring unit 14a can also be provided only at some of the foil units 1a. In this case, only partial internal channels P of the hydrodynamic gas bearing 1 are radially blocked. Compared with the case where no retaining ring unit 14a is provided for radial flow blocking, the damping can also be increased to a certain extent.

[0098] On the basis of the aforementioned circumferential flow blocking and / or radial flow blocking, in order to ensure the working reliability of the hydrodynamic gas bearing 1, the present invention also provides an air flow preselection structure 15 in the hydrodynamic gas bearing 1. The air flow preselection structure 15 is used to preprocess the air flow, guiding the air flow to have a speed consistent with the rotation direction of the rotor 2 when flowing into the hydrodynamic gas bearing 1, so that in the case of circumferential flow blocking and / or radial flow blocking, the hydrodynamic gas bearing 1 can still obtain the gas flow required to form the hydrodynamic effect, and further realize the reliable support of the hydrodynamic gas bearing 1 for the rotor 2.

[0099] Refer to Figure 5 , 9 , 11 and 12, when the hydrodynamic gas bearing 1 is an axial hydrodynamic gas bearing, the air flow preselection structure 15 can include an inclined groove 151. The inclined groove 151 is provided at at least one of the two ends of the intake channel P along the radial direction of the shaft hole 111, and the inclined groove 151 is arranged obliquely with respect to the radial direction of the shaft hole 111.

[0100] The two ends of the intake passage P in the radial direction of the axial hole 111 are the air inlets of the hydrodynamic gas bearing 1. At the air inlets, inclined grooves 151 are arranged, which can guide the air flow direction not only along the radial direction of the axial hole 111, but also have a velocity along the rotation direction of the rotor 2. In this way, when the air flow flows into the bearing from the air inlet, its direction is along the rotation direction of the rotor 2, which can reduce the energy loss of the air flow, is beneficial to providing sufficient gas flow required for forming the hydrodynamic effect for the hydrodynamic gas bearing 1, and is also beneficial to improving the air flow stability at the air inlet, so that the hydrodynamic gas bearing 1 can support the rotor 2 more reliably.

[0101] Although compared with the case where the inclined groove 151 is not provided, setting the inclined groove 151 at only one air inlet of the intake passage P can play a certain role in preselecting the air flow, but setting the inclined grooves 151 at both air inlets of the intake passage P can achieve a better air flow preselection effect. At this time, the inclined directions of the two inclined grooves 151 on the same intake passage P with respect to the radial direction of the axial hole 111 are opposite.

[0102] The following Figures 1 - 13 illustrated embodiments are used to further illustrate the present invention.

[0103] As Figures 1 - 13 shown, in this embodiment, the hydrodynamic gas bearing 1 is an axial hydrodynamic gas bearing, which includes a housing 11, a foil structure, a radial flow blocking structure 14, etc.

[0104] From Figure 1 and Figure 5 it can be seen that the housing 11 is in a disc shape, and a shaft hole 111 is provided at its center. The shaft hole 111 is matched with the rotating shaft 21 of the rotor 2. During use, the rotating shaft 21 is inserted into the shaft hole 111. The thrust disc 22 of the rotor 2 is located on one axial side of the housing 11 and is used to cooperate with the foil structure to form a working gap, so as to form a hydrodynamic gas film during the rotation of the rotor 2 and realize the supporting effect on the rotor 2.

[0105] The foil structure is arranged on the housing 1 and is used to cooperate with the thrust disc 22 to form a working gap and elastically support the rotating shaft 2.

[0106] As Figures 4 - 5 shown, the foil structure includes foil units 1a. In order to improve the surface force uniformity of the thrust bearing, the number of foil units 1a is an even number, and these even-numbered foil units 1a are evenly arranged along the circumferential direction of the shaft hole 111. Specifically, as Figure 5 shown, in this embodiment, the foil structure includes 8 fan-shaped foil units 1a, and an intake passage P is formed between adjacent foil units 1a.

[0107] To simplify the structure, each foil unit 1a has the same structure. Therefore, only one of the foil units 1a will be described as an example below.

[0108] As Figure 4 shown, the foil unit 1a includes a top foil 12 and a corrugated foil 13. Among them, the top foil 12 is used to cooperate with the thrust disk 22 to form a working gap. The corrugated foil 13 is located between the top foil 12 and the housing 1 and is used to elastically support the top foil 12.

[0109] The corrugated foil 13 includes a corrugated unit 13a. The corrugated unit 13a includes a first part 131 and a second part 132 that are connected to each other. The first part 131 is a wave trough, which contacts the inner wall of the housing 1 and is linear, that is, the first part 131 is a straight section. The second part 132 of the corrugated unit 13a is a wave crest, which protrudes from the first part 131 toward the top foil 12 and is arc-shaped, that is, the second part 132 is an arched section.

[0110] The corrugated foil 13 includes a plurality of corrugated units 13a circumferentially distributed along the shaft hole 111. And in two adjacent corrugated units 13a, the first part 131 of one corrugated unit 13a is connected to the second part 132 of the other corrugated unit 13a. In this way, the corrugated foil 13 is corrugated.

[0111] As Figure 4 shown, in this embodiment, the top foil 12 includes a mating unit 12a that mates with the aforementioned corrugated unit 13a one by one. The mating unit 12a includes a first mating portion 121 in the shape of a trapezoid and a second mating portion 122 in a straight line. The first mating portion 121 and the second mating portion 122 are connected to each other. And in two adjacent mating units 12a, the first mating portion 121 of one mating unit 12a is connected to the second mating portion 122 of the other mating unit 12a.

[0112] Among them, the first mating portion 121 protrudes toward the first part 131 side relative to the second mating portion 122 (specifically in Figure 4 it is protruding from the thrust disk 22 side toward the housing 1 side), and mates with the first part 131 to form a first gap G1 along the axis of the shaft hole 111. At the same time, the first mating portion 121 also mates with two second parts 132 adjacent to itself in the circumferential direction to form a first cavity V1 and a second cavity V2 on both circumferential sides of the first gap G.

[0113] The second mating portion 122 corresponds to the second part 132 and mates with the second part 132 to form a second gap G2 along the axis of the shaft hole 111.

[0114] Specifically, the longitudinal section of the first engaging portion 121 is trapezoidal, which includes a first connecting body 121a and a second connecting body 121b that form the two waists of the trapezoid, and a third connecting body 121c connected between the first connecting body 121a and the second connecting body 121b. The third connecting body 121c forms the bottom side of the trapezoid. Among them, the third connecting body 121 is linear and cooperates with the linear first portion 131 to form a first gap G1 therebetween. The first connecting body 121a and the second connecting body 121b are respectively connected to two second engaging portions 122 adjacent to each other in the circumferential direction of the top foil 12. Among them, the first connecting body 121a is connected to the second engaging portion 122 of the adjacent engaging unit 12a and cooperates with the second portion 132 adjacent to itself to form a first cavity V1 therebetween. The second connecting body 121b is connected to the second engaging portion 122 of the same engaging unit 12a corresponding to itself and cooperates with the second portion 132 adjacent to itself to form a second cavity V2 therebetween. And along the direction from the top foil 13 to the housing 11, the first connecting body 121a and the second connecting body 121b approach each other.

[0115] Based on the above settings, in a process section (corresponding to a wavy unit 13a, in other words, corresponding to a waveform), along the rotation direction of the rotor 2 (as Figure 4 indicated by the arrow in the figure), a first cavity V1, a first gap G1, a second cavity V2, and a second gap G2 are sequentially formed between the top foil 12 and the wavy foil 13, and the flow areas of the first gap G1 and the second gap G2 are smaller than the flow areas of the first cavity V1 and the second cavity V2.

[0116] During operation, the process of the gas flowing through this process section is as follows: The gas q that converges in the first cavity V1 before the rotor 2 rotates makes a circumferential movement driven by the rotor 2. When flowing through the first gap G1, it is approximately an ideal throttling process, and the pressure of the gas q decreases and the velocity increases. Next, it enters the second cavity V2. Due to the sudden increase in the flow area, the gas q forms a strong vortex, making the velocity almost completely disappear, and the pressure is approximately considered unchanged, that is, equal to the pressure in the first gap G1. Next, the gas q flows through the second gap G2 and repeats the throttling process again, resulting in a decrease in pressure and an increase in velocity. It can be seen that the gas q repeats the throttling twice when flowing through a single process section.

[0117] The entire foil structure has multiple such process segments. When the gas flows through each process segment, the above process is repeated. As the gas continues to flow backward along the rotation direction, the specific volume of gas q becomes larger and larger, and the velocity and pressure drop when flowing through the gap become larger and larger. This makes the pressure between the top foil 12 and the corrugated foil 13 tend to the back pressure, playing a comb seal role, effectively blocking the circumferential air flow, and reducing the circumferential flow capacity. Since this can weaken the cooling and lubrication effects generated by the circumferential flow of the air flow, the Coulomb friction effect of the bearing can be improved and the damping can be increased.

[0118] Moreover, the first mating portion 12 of this embodiment can also contact the corrugated foil 13 when the deformation amount of the corrugated foil 13 is relatively large and participate in the deformation, providing additional stiffness for the bearing and increasing the contact area between the top foil 12 and the corrugated foil 13. In this regard, the damping of the hydrodynamic gas bearing 1 can also be increased.

[0119] Combined Figure 4 with Figure 8 it can be known that the corrugated corrugated foil 13 forms an internal flow passage F with the top foil 12 and the housing 11. For example, in this embodiment, an arched internal flow passage F is formed between the second portion 132 of the corrugated foil 13 and the housing 11.

[0120] When both openings at the radial two ends of the internal flow passage F are open, external gas can enter the internal flow passage F and flow along the internal flow passage F, that is, the air flow can flow radially along the axis hole 111 through these internal flow passages F, which also affects the damping characteristics of the hydrodynamic gas bearing 1.

[0121] In order to further solve the problem of relatively small damping caused by this radial flow, as Figures 5 - 8 and Figure 13 shown, this embodiment also provides a radial flow blocking structure 14 on the housing 1. The radial flow blocking structure 14 is used to block the connection between the internal flow passage F and the outside in the radial direction of the axis hole 111.

[0122] Among them, as Figure 5 shown, the radial flow blocking structure 14 includes retaining ring units 14a corresponding to the foil units 1a one by one, and each retaining ring unit 14a includes two arc-shaped retaining rings 141. In the same retaining ring unit 14a, the two retaining rings 141 are respectively located at the radial two ends of the foil unit 1a, and along the circumferential direction, each retaining ring 141 extends from one end of the foil unit 1a to the other end. At the same time, along the axial direction, each retaining ring 141 extends from the housing 11 to be flush with the second mating portion 122 of the top foil 12, that is, the height H of the retaining ring 141 is equal to the height of the top foil 12 (that is, the distance d between the end of the top foil 12 far from the housing 11 (specifically the second mating portion 122 in Figure 8 and the housing 11)).

[0123] In view of the above settings, the retaining ring 141 shields the radial ports of all the internal flow channels F of the foil unit 1a, and the radial flow blocking structure 14 shields the radial two-end openings of all the internal flow channels F of the foil unit 1a, so that there is no longer radial fluid communication between the internal flow channels F and the outside of the housing 1, and between the internal flow channels F. Since the airflow along the radial direction into the internal flow channels F can be blocked, the radial flow blocking effect can be achieved, effectively improving the damping of the hydrodynamic gas bearing 1.

[0124] In addition, as Figure 5 , Figure 9 , Figure 11 and Figure 12 shown, in this embodiment, an airflow preselection structure 15 is further provided on the housing 11. The airflow preselection structure 15 is used to make the airflow have a speed along the rotation direction of the rotor 2 when flowing into the hydrodynamic gas bearing 1 through the intake channel P.

[0125] Among them, as Figure 9 , 11 and FIG. 12 shown, the airflow preselection structure 15 of this embodiment includes a pair of inclined grooves corresponding to the intake channel P one by one. The pair of inclined grooves includes two inclined grooves 151 provided at the radial two ends of the intake channel P. Each inclined groove 151 is inclined, and in the same pair of inclined grooves, the inclination directions of the two inclined grooves 151 are opposite. In this way, the air inlets of the intake channel P are all inclined, so that the airflow can be preselected, so that when the gas flows into the bearing through the air inlet, it all has a swirling direction consistent with or similar to the rotation direction of the rotor 2, and further can ensure that the hydrodynamic gas bearing 1 obtains sufficient gas flow required for forming the hydrodynamic effect, and improves the airflow stability at the air inlet, reducing the airflow loss.

[0126] It can be seen that the hydrodynamic gas bearing 1 of this embodiment has circumferential and radial flow blocking effects, good friction effect, large damping, can effectively reduce the amplitude of the shafting, realize a higher stable rotation process, and has an intake preselection function, which can complement the circumferential and radial flow blocking structures, effectively improving the reliability of the hydrodynamic gas bearing 1.

[0127] The hydrodynamic gas bearing 1 of the present invention can be applied to various rotating machines such as compressors or centrifuges. Therefore, the present invention also provides a rotating machine, which includes a rotor 2 and the hydrodynamic gas bearing 1 of the present invention. A working gap is formed between the top foil 12 of the hydrodynamic gas bearing and the rotor 2.

[0128] The above are only exemplary embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A hydrodynamic gas bearing (1), characterized in that, Comprising: A housing (11) having a shaft hole (111) for inserting a rotor (2); And A foil unit (1a) provided on the housing (11) and comprising: A top foil (12) for forming a working gap with the rotor (2); and A wave foil (13) located between the top foil (12) and the housing (11), and comprising a wave unit (13a), the wave unit (13a) including a first part (131) and a second part (132) connected to each other, the first part (131) being in contact with the inner wall of the housing (11), the first part (131) being one of a wave trough and a wave crest, the second part (132) being the other of the wave trough and the wave crest, and the first parts (131) and the second parts (132) of two adjacent wave units (13a) along the circumferential direction of the shaft hole (111) being connected; Wherein, the top foil (12) includes a fitting unit (12a), the fitting unit (12a) corresponding to the wave unit (13a) one by one and including a first fitting portion (121) and a second fitting portion (122) connected to each other, the first fitting portion (121) and the second fitting portion (122) corresponding to the first part (131) and the second part (132) respectively, the first fitting portions (121) and the second fitting portions (122) of two adjacent fitting units (12a) along the circumferential direction of the shaft hole (111) being connected, and the first fitting portion (121) protruding from the second fitting portion (122) towards the first part (131), there being a first gap (G1) between the first fitting portion (121) and the first part (131), there being a second gap (G2) between the second fitting portion (122) and the second part (132), first cavities (V1) and second cavities (V2) being respectively formed between the first fitting portion (121) and two adjacent second parts (132), and the flow-through areas of the first gap (G1) and the second gap (G2) being both smaller than the flow-through areas of the first cavities (V1) and the second cavities (V2).

2. The hydrodynamic gas bearing (1) according to claim 1, characterized in that, The first mating portion (121) includes a first connecting body (121a), a second connecting body (121b), and a third connecting body (121c). The first connecting body (121a) is connected to the second mating portion (122) of the adjacent mating unit (12a). The second connecting body (121b) is connected to the second mating portion (122) of the same mating unit (12a) corresponding to itself. Both the first connecting body (121a) and the second connecting body (121b) extend from the second mating portion (122) they are connected to towards the direction close to the first portion (131). The third connecting body (121c) connects the first connecting body (121a) and the second connecting body (121b). The first gap (G1) is located between the third connecting body (121c) and the corresponding first portion (131). The first cavity (V1) is located between the first connecting body (121a) and the second portion (132) adjacent to itself. The second cavity (V2) is located between the second connecting body (121b) and the second portion (132) adjacent to itself.

3. The hydrodynamic gas bearing (1) according to claim 2, wherein, Along the direction from the top foil (12) to the housing (11), the first connecting body (121a) and the second connecting body (121b) approach each other.

4. The hydrodynamic gas bearing (1) according to claim 2, characterized in that, The third connecting body (121c) is linear, serrated, or arc-shaped.

5. The hydrodynamic gas bearing (1) according to claim 1, characterized in that, The first mating portion (121) is trapezoidal or rectangular.

6. The hydrodynamic gas bearing (1) according to claim 1, characterized in that, The wave trough is linear; and / or, the wave crest is arc-shaped.

7. The hydrodynamic gas bearing (1) according to claim 1, characterized in that, The first portion (131) is a wave trough, and the second portion (132) is a wave crest.

8. The hydrodynamic gas bearing (1) according to any one of claims 1-7, characterized in that, The hydrodynamic gas bearing (1) is an axial hydrodynamic gas bearing (1). The hydrodynamic gas bearing (1) includes a plurality of foil units (1a). The plurality of foil units (1a) are arranged along the circumference of the shaft hole (111), and an intake channel (P) is provided between adjacent foil units (1a).

9. The hydrodynamic gas bearing (1) according to claim 8, characterized in that, An internal flow path (F) is formed between the wave foil (13), the top foil (12), and the housing (11). The hydrodynamic gas bearing (1) further includes a radial flow blocking structure (14). The radial flow blocking structure (14) is provided on the housing (11) and is used to block the communication of the internal flow path (F) with the outside in the radial direction of the shaft hole (111).

10. The hydrodynamic gas bearing (1) according to claim 9, characterized in that, The radial flow blocking structure (14) includes a retaining ring unit (14a) corresponding to the foil unit (1a). The retaining ring unit (14a) shields at least one of the two openings at both ends of the internal flow path (F) along the radial direction of the shaft hole (111).

11. The hydrodynamic gas bearing (1) according to claim 10, characterized in that, The retaining ring unit (14a) includes a retaining ring (141). The retaining ring (141) is provided at at least one of the two ends of the foil unit (1a) along the radial direction of the shaft hole (111), and the retaining ring (141) extends from the housing (11) along the axial direction of the shaft hole (111) to be flush with or higher than the end of the top foil (12) away from the housing (11).

12. The hydrodynamic gas bearing (1) according to claim 11, characterized in that, The retaining rings (141) are provided at both ends of the foil unit (1a) in the radial direction of the shaft hole (111).

13. The hydrodynamic gas bearing (1) according to claim 10, characterized in that, The retaining ring units (14a) correspond to the foil units (1a) one by one.

14. The hydrodynamic gas bearing (1) according to claim 8, characterized in that, An air flow preselection structure (15) is provided on the air intake passage (P), and the air flow preselection structure (15) is configured to enable the air flow to have a velocity in the rotational direction of the rotor (2) when flowing into the hydrodynamic gas bearing (1) through the air intake passage (P).

15. The hydrodynamic gas bearing (1) according to claim 14, characterized in that, The air flow preselection structure (15) includes an inclined groove (151), and the inclined groove (151) is provided at at least one of the two ends of the air intake passage (P) in the radial direction of the shaft hole (111), and the inclined groove (151) is arranged obliquely with respect to the radial direction of the shaft hole (111).

16. The hydrodynamic gas bearing (1) according to claim 15, characterized in that, The inclined grooves (151) are provided at both ends of the air intake passage (P) in the radial direction of the shaft hole (111), and the two inclined grooves (151) on the air intake passage (P) are inclined in opposite directions with respect to the radial direction of the shaft hole (111).

17. A rotating machine, comprising a rotor (2), characterized in that, It further includes a hydrodynamic gas bearing (1) according to any one of claims 1-16, and a working gap is formed between the top foil (12) of the hydrodynamic gas bearing (1) and the rotor (2).

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