Title

Bump Foil Used in Thrust Bearings and Corresponding Thrust Bearing and

Device

Technical field

The present invention relates to a bump foil used in thrust bearings. The present invention also relates to a thrust bearing with the bump foil and a device with the thrust bearing.

Background of the invention

In the prior art, in order to limit the axial movement of a rotating body during rotation, a known method is to use a thrust bearing. The bump foil type dynamic pressure gas thrust bearing, as a known thrust bearing type, is widely used in air compressors.

Figures 1 to 4 are schematic diagrams of the structure of the bump foil type dynamic pressure gas thrust bearing 10 known from the prior art. This thrust bearing 10 has top foils 200 serving as the bearing surface, bump foils 100’ for elastically supporting the top foils 200, and a base plate 300 for supporting the top foils 200 and the bump foils 100’.

Further, a plurality of top foils 200 are successively arranged in the circumferential direction of the thrust bearing 10, and each top foil 200 is in the form of a planar thin plate with one circumferential edge 210 fixed and the opposite circumferential edge 220 free. Exemplarily, each top foil 200 is in the shape of a ring section, for example, a sector shape.

A plurality of bump foils 100’ are successively, for example, at an interval, in particular at an equal angular interval, arranged in the circumferential direction of the thrust bearing 10. Each bump foil 100’ is in the form of a corrugated thin plate with one circumferential edge 180’ fixed and the opposite circumferential edge 190’ free, thereby enabling the bump foil 100’ to extend to different extents as the pressure load changes.

Each bump foil 100’ has a plurality of convexes 110’ and concaves 120’ arranged alternately, wherein each of the convexes 110’ and the concaves 120’ extend parallel to each other along a direction inclined with respect to the radial direction.

The following fact can be known from measuring the pressure load on the thrust bearing 10: in a cyclical section of the thrust bearing 10 (the section between the dashed lines 11 and 12 in Figure 4), pressure load distribution on the bump foil 100’ is not uniform, but shows an obvious pressure load peak 130’. From the measured pressure-angle curve 50 in a cyclical section shown in Figure 5A, it can be seen that the pressure load peak 130’ on the bump foil 100’ is located between 20° and 30°, approximately around 24°; from the measured two- dimensional pressure profile 60 shown in Figure 5B, it can be seen that the pressure load peak 130’ represented by the darker region 13 is largely located at the concave 120’ near the front 161’ of the radially outermost cut 160’ at the free edge 190’, for example, located in the regions in the dashed arcs 14, 15 and 16 shown in Figures 2 to 4.

The fact that the pressure load peak 130’ is located largely at the concave 120’ near the free edge 190’ of the bump foil 100’ will hinder the formation of the gas film. Thus, without an effective gas film, the concave 120’ with a limited elastic deformation will transmit most of the pressure load from the rotating body to the base plate 300, which is then transmitted to the bearing component used for axially supporting the thrust bearing 10, resulting in a significantly higher pressure load on the regions of the base plate 300 and the bearing component corresponding to the pressure load peak 130’ than the remaining region thereof, and thus causing obvious fatigue hot spots in the base plate 300 and the bearing component and therefore significantly shortening the service life of the thrust bearing 10 and the bearing component. Therefore, it is desirable to provide a solution that can improve the pressure load distribution on the bump foil and thus eliminate the fatigue hot spots in the thrust bearing.

Brief summary of the invention

The purpose of the present invention is achieved by a bump foil used in thrust bearings. The bump foil is in the form of a section of an annular or ring-shaped thin plate and comprises a corrugated region, the corrugated region comprises at least one convex and at least one concave, and the convex and the concave are alternately arranged in the circumferential direction, wherein the bump foil is constructed such that at least two of the convexes and the concaves extend toward the outer circumference of the bump foil and away from each other.

According to one optional embodiment of the present invention, most, in particular all, of the at least one convex or most, in particular all, of the at least one concave extend toward the outer circumference of the bump foil and away from each other.

According to one optional embodiment of the present invention, the bump foil is constructed such that the extension directions of the convexes or the concaves extending away from each other essentially start from a single point, wherein the point is located in a circle defined by the inner circumference of the bump foil or by the inner circumference of a base plate used for carrying the bump foil.

According to one optional embodiment of the present invention, the bump foil is constructed such that a plurality of convexes and/or concaves extending away from each other extend along the radial direction of the bump foil, the base plate or the thrust bearing.

According to one optional embodiment of the present invention, the bump foil is constructed such that the peak lines or center lines of the plurality of convexes extending away from each other point to the corresponding axial center line of the bump foil, the base plate or the thrust bearing.

According to one optional embodiment of the present invention, the bump foil is constructed such that the bottom lines or center lines of the plurality of concaves extending away from each other point to the corresponding axial center line of the bump foil, the base plate or the thrust bearing.

According to one optional embodiment of the present invention, the bump foil has an inner ring portion and an outer ring portion located radially outside the inner ring portion, and the convexes or the concaves in the inner ring portion are radially aligned with the convexes or the concaves in the outer ring portion.

According to one optional embodiment of the present invention, the convexes or concaves from the inner ring portion and the convexes or concaves from the outer ring portion that are radially aligned with each other extend in the same radial direction.

According to one optional embodiment of the present invention, the bump foil has an inner ring portion and an outer ring portion located radially outside the inner ring portion, wherein the convexes in the inner ring portion are staggered at an angle from the convexes in the outer ring portion or the concaves in the inner ring portion are staggered at an angle from the concaves in the outer ring portion.

According to one optional embodiment of the present invention, the bump foil also has a flat region beside the corrugated region, and the bump foil is fixed to the base plate of the thrust bearing at the flat region.

The purpose of the present invention is also achieved by a thrust bearing, comprising top foils having a bearing surface, bump foils used to elastically support the top foils, and a base plate used to carry the top foils and the bump foils, wherein the bump foils are located on the base plate and the top foils are located above the bump foils, and the bump foils are constructed as the bump foil described above.

The purpose of the present invention is also achieved by a device, which has a rotating part and the thrust bearing described above used to limit axial movement of the rotating part.

Through the present invention, the region of the pressure load peak occurs at a position mainly including a convex, thereby reducing the transmission of the pressure load at the pressure load peak from the rotating part to the base plate and the bearing component by means of the larger elastic force of the convex, and thus eliminating fatigue hot spots in the thrust bearing and the bearing component.

Other advantages and advantageous embodiments of the subject of the present invention are obvious from the description, drawings and claims.

Brief description of the drawings

More features and advantages of the present invention are further elaborated in the following detailed description of specific embodiments with reference to the accompanying drawings. The drawings are:

Figure 1 is a 3D view of the bump foil type dynamic pressure gas thrust bearing according to the prior art;

Figure 2 is a local perspective view of the bump foil type dynamic pressure gas thrust bearing according to the prior art, wherein part of the top foil is removed; Figure 3 is a local top view of the bump foil type dynamic pressure gas thrust bearing according to the prior art, wherein the top foil is removed;

Figure 4 is a schematic diagram of the structure of the bump foil type dynamic pressure gas thrust bearing according to the prior art;

Figure 5A is a pressure-angle curve of a cyclic section of the bump foil according to the prior art;

Figure 5B is a two-dimensional pressure profile of the bump foil according to the prior art;

Figure 6 is a schematic diagram of the structure of the innovative bump foil used in bump foil type dynamic pressure gas thrust bearings according to one exemplary embodiment of the present invention; and

Figure 7 is a flowchart of the method for manufacturing bump foils according to one exemplary embodiment of the present invention.

Detailed description of the embodiments

The present invention is further described in detail with reference to the drawings and a plurality of exemplary embodiments, so that the technical issues to be addressed by the present invention and the technical solution and technical benefits become clearer. It should be understood that the specific embodiments described here are only used to explain the present invention, and are not used to limit the scope of the present invention. In the drawings, the same or similar reference numerals indicate the same or equivalent elements.

It should be noted here that, in the context herein, unless otherwise defined, the term “radial direction” may be understood as any or several of the radial direction of the bump foil, the radial direction of the base plate, and the radial direction of the thrust bearing as a whole.

Figure 6 is a schematic diagram of the structure of the bump foil 100 according to one exemplary embodiment of the present invention. The bump foil 100 can replace the aforementioned bump foil 100’ and be used in the bump foil type dynamic pressure gas thrust bearing described above with reference to Figures 1 to 4.

The bump foil 100 is in the shape of a section of a ring (also referred to as a circular section herein), for example, the sector shape shown in Figure 6. In this case, the bump foil type dynamic pressure gas thrust bearing may comprise two or more bump foils 100, and the two or more bump foils 100 are successively arranged at an interval in the circumferential direction. Alternatively, the bump foil 100 is in the shape of a complete ring. In this case, the bump foil type dynamic pressure gas thrust bearing may comprise a single bump foil 100.

The bump foil 100 is in the form of a corrugated thin plate and comprises a corrugated region 150 and a flat region 140 located beside the corrugated region 150. In the assembled state of the thrust bearing, the bump foil 100 is fixed to the base plate 300 at its flat region 140, for example by welding (see Figure 1), and the corrugated region 150 is free relative to the base plate 300 so that it can stretch or contract to adapt to the magnitude of the pressure load.

The corrugated region 150 comprises at least one, in particular a plurality of, convex(es) 110 (as shown by the shaded bars in Figure 6) and at least one, in particular a plurality of, concave(s) 120 (the regions between the shaded bars in Figure 6). According to the present invention, the convex 110 and the concave 120 may be defined in the following manner: the plane where the flat region 140 is located is used to divide the corrugated region 150 in a natural state, the portion of the corrugated region 150 located above the plane is referred to as the convexes 110, and the portion of the corrugated region 150 below the plane is referred to as the concaves 120. In addition, in the case where all regions other than the convexes 110 in the corrugated region 150 are located on the plane, these remaining regions may also be referred to as concaves. Similarly, in the case where all regions other than the concaves 120 in the corrugated region 150 are located on the plane, these remaining regions may also be referred to as convexes.

In one exemplary embodiment, the convexes 110 and the concaves 120 are alternately arranged successively along the circumferential direction. A concave 120 is always adjacent to a convex 110, and a convex 110 is always adjacent to a concave 120.

In an example of the present invention, the corrugated region 150 is in a wave structure, for example, a sine wave structure or a cosine wave structure. In this case, the convex 110 corresponds to the crest of the wave structure, and the concave 120 corresponds to the trough of the wave structure.

According to the present invention, the bump foil 100 is constructed such that a plurality of, for example, most of, in particular all of, the convexes 110 are distributed in such a way as to diverge radially outward. Additionally or alternatively, the bump foil 100 is constructed such that a plurality of, for example, most of, in particular all of, the concaves 120 are distributed in such a way as to diverge radially outward.

In particular, the bump foil 100 is constructed such that a plurality of, for example, most of, in particular all of, the convexes 110 and/or the concaves 120 have their extension lines pointing to a single point, wherein the point is located in a circle defined by the inner circumference 171 of the bump foil 100 or by the inner circumference 320 of the base plate 300 (see Figure 2).

More particularly, the bump foil 100 is constructed such that a plurality of, for example, most of, in particular all of, the convexes 110 and/or the concaves 120 extend along the radial direction of the bump foil 100, the base plate 300 or the thrust bearing. That is, the bump foil 100 is constructed such that a plurality of, for example, most of, in particular all of, the convexes 110 and/or the concaves 120 extend essentially toward the same center of a circle, which may be the center of any of the following circles: the inner circle defined by the inner circumference 171 of the bump foil 100, the outer circle defined by the outer circumference 172 of the bump foil 100, the inner circle defined by the inner circumference 320 of the base plate 300, the outer circle defined by the outer circumference 330 of the base plate 300, or the center O of the thrust bearing with the bump foil 100 (see Figure 1). Any two or more of these centers of circles may coincide.

Within the scope of the present invention, the extension direction of the longitudinal center line of each convex 110 may be used to represent the extension direction of the corresponding convex 110, and the extension direction of the longitudinal center line of each concave 120 may be used to represent the extension direction of the corresponding concave 120. In the case where the convex 110 has a single peak line (i.e., the line connecting the upper vertices), the extension direction of the peak line may also be used to represent the extension direction of the convex. Similarly, in the case where the concave 120 has a single bottom line (i.e., the line connecting the lower vertices), the extension direction of the bottom line may also be used to represent the extension direction of the concave. Accordingly, the statement that the convex 110 extends essentially along the radial direction of the bump foil 100, the base plate 300, or the thrust bearing may be understood as meaning that the peak line or center line of the convex 110 points to the corresponding axial center line of the bump foil 100, the base plate 300 or the thrust bearing, wherein the corresponding axial center line of the bump foil 100, the base plate 300 or the thrust bearing extends through its respective center of the circle. Similarly, the statement that the concave 120 essentially extends in the radial direction of the bump foil 100, the base plate 300 or the thrust bearing may be understood as meaning that the bottom line or center line of the concave 120 points to the corresponding axial center line of the bump foil 100, the base plate 300 or the thrust bearing. The dotted line in Figure 1 represents the axial center line P-P extending through the center O of the thrust bearing.

By arranging the convexes 110 and/or the concaves 120 on the bump foil 100 in such a way as to diverge radially outward, the pressure load peak 130 can occur at the position mainly including a convex 110, for example, the convex 110 near the front 161 of the radially outermost cut 160 at the free edge 190, in a region indicated by the dashed arc 17 in Figure 6. In this case, the greater elastic force of the convex 110 may help to reduce the transmission of the pressure load at the pressure load peak 130 from the rotating part to the base plate 300 and the bearing component, thereby significantly suppressing the adverse effect of the pressure load peak 130 on the thrust bearing and the bearing component in comparison with the bump foil 100’ with parallel inclined convexes 110’ and/or concaves 120’, and thus eliminating the fatigue hot spots in the thrust bearing and the bearing component and effectively extending the service life thereof.

According to one exemplary embodiment, a plurality of convexes 110 extending away from each other on the same bump foil 100 may have a uniform geometric design, i.e., the same geometry and the same dimensions. Alternatively, a plurality of convexes 110 extending away from each other on the same bump foil 100 may have different geometric designs, for example, different geometries (for example, the crest shape, or the crest trend) and/or different dimensions (for example, the width, or the height).

Additionally or alternatively, a plurality of concaves 120 extending away from each other on the same bump foil 100 may have a uniform geometric design, i.e., the same geometry and the same dimensions. Alternatively, a plurality of concaves 120 extending away from each other on the same bump foil 100 may have different geometric designs, for example, different geometries (for example, the crest shape, or the crest trend) and/or different dimensions (for example, the width, or the height).

According to one exemplary embodiment of the present invention, each of a plurality of convexes 110 extending away from each other may have a constant geometric design, for example, a constant geometry and constant dimensions, along its extension direction. Alternatively, each of a plurality of convexes 110 extending away from each other may have varied geometric designs, for example, varied geometries and/or varied dimensions, along its extension direction.

Additionally or alternatively, each of a plurality of concaves 120 extending away from each other may have a constant geometric design, i.e., a constant geometry and constant dimensions, along its extension direction. Alternatively, each of a plurality of concaves 120 extending away from each other may have varied geometric designs, for example, varied geometries and/or varied dimensions, along its extension direction. According to one exemplary embodiment of the present invention, the convexes 110 and/or the concaves 120 extending away from each other narrow from the outside to the inside in the radial direction. Exemplarily, with reference to Figure 6, the convex 110 has a constant width W _p along its extension direction, and the width W _v of the concave 120 decreases from outside to inside in the radial direction, wherein the widths W _p and W _v represent the dimensions of the convex and the concave in the direction transverse to their extension direction. Alternatively, the concave 120 has a constant width W _v along its extension direction, while the width W _p of the convex 110 may decrease from outside to inside in the radial direction. Alternatively, one of the convex 110 and the concave 120 has a width decreasing from outside to inside along the radial direction, while the other has a width increasing from outside to inside along the radial direction.

In one example of the present invention, the convexes 110 of the same bump foil 100 are spaced at an equal angle. Additionally or alternatively, the concaves 120 of the same bump foil 100 are spaced at an equal angle.

According to one exemplary embodiment of the present invention, at least one cut 160 extending essentially in the circumferential direction is provided to divide at least the corrugated region 150 of the bump foil 100 into at least two concentric ring sections. When one cut 160 is provided, the corrugated region 150 is divided into an inner ring portion and an outer ring portion; when two cuts 160 are provided, the corrugated region 150 is divided into an inner ring portion 151, a middle ring portion 152 and an outer ring portion 153, as shown in Figure 6.

In one example, the cut 160 is provided to cross the entire thickness of the bump foil 100 in the axial direction.

According to one exemplary embodiment of the present invention, all the convexes 110 and/or all the concaves 120 in each of the ring portions 151, 152 and 153 of the bump foil 100 extend along their respective radial directions.

According to one exemplary embodiment of the present invention, the convexes 110 in one of the at least two ring portions 151, 152 and 153 are radially aligned with the convexes 110 in at least one other, for example, an adjacent, ring portion, so that a plurality of convexes 110 from different ring portions that are radially aligned with each other extend along a single radial direction, and in particular the respective center lines or peak lines of the plurality of convexes extend in the same radial direction.

Additionally or alternatively, the concaves 120 in one of the at least two ring portions 151, 152 and 153 are radially aligned with the concaves 120 in at least one other, for example, an adjacent, ring portion, so that a plurality of concaves 120 from different ring portions that are radially aligned with each other extend along a single radial direction, and in particular the respective center lines or bottom lines of the plurality of concaves extend in the same radial direction.

Additionally or alternatively, the convexes 110 in one of the at least two ring portions 151, 152 and 153 are radially staggered, i.e., arranged at an angle, from the convexes 110 in at least one other, for example, an adjacent, ring portion, so that a plurality of convexes 110 from different ring portions that are radially staggered with each other extend along different radial directions pointing to a single center of circle, and in particular the respective center lines or peak lines of the plurality of convexes extend in different radial directions pointing to the same center of circle.

Additionally or alternatively, the concaves 120 in one of the at least two ring portions 151, 152 and 153 are radially staggered, i.e., arranged at an angle, from the concaves 120 in at least one other, for example, an adjacent, ring portion, so that a plurality of concaves 120 from different ring portions that are radially staggered with each other extend along different radial directions pointing to a single center of circle, and in particular the respective center lines or bottom lines of the plurality of concaves extend in different radial directions pointing to the same center of circle.

In one example, the convexes 110 in one of the at least two ring portions 151,

152 and 153 are radially aligned with the concaves 120 in at least one other, for example, an adjacent, ring portion, so that the center line or peak line of a convex 110 and the center line or bottom line of the concave 120 aligned with it extend along a single radial direction. It should be noted here that the radial alignment only defines the angular positional relationship between convexes 110 and/or concaves 120 from different ring portions, and is not intended to limit the width relationship between convexes 110 and/or concaves 120 that are radially aligned with each other. For example, the convexes 110 and/or the concaves 120 that are radially aligned with each other may have continuous or discontinuous and matching or non-matching width designs.

In another aspect, the present invention provides a bump foil type dynamic pressure gas thrust bearing, which comprises top foils 200 having the bearing surface, bump foils 100 for elastically supporting the top foils 200, and a base plate 300 for supporting the top foils 200 and the bump foils 100. The only difference between the bump foil type dynamic pressure gas thrust bearing and the thrust bearing 10 described above with reference to Figures 1 to 5 is that it uses the bump foil 100 described above with reference to Figure 6. Therefore, other features and details of the thrust bearing according to the present invention can be found in the corresponding description with reference to Figures 1 to 5 above, and will not be repeated here.

In one exemplary embodiment according to the present invention, the thrust bearing has a plurality of bump foils 100, and the plurality of bump foils 100 are successively, for example, at an interval, in particular at an equal angular interval, arranged in the circumferential direction of the thrust bearing. Additionally or alternatively, the plurality of bump foils 100 are successively, for example, at an interval, arranged in the radial direction of the thrust bearing.

In one exemplary embodiment according to the present invention, a plurality of top foils 200 and a plurality of bump foils 100 are correspondingly arranged in the axial direction, so that each bump foil 100 has a corresponding top foil 200 above it.

In yet another aspect, the present invention provides a method for manufacturing the bump foil 100. As shown in Figure 7, in this method, a plate-shaped raw material is provided in step S10. Then, in step S20, the plate-shaped raw material is cut to obtain a sector-shaped base material. Next, in step S30, the sector-shaped base material is corrugated to form the corrugated region 150 described above. Then, in step S40, at least one cut 160 described above is formed in the sector-shaped base material by means of an appropriate process. Then, optionally, in step S50, cutting is performed on the sector-shaped base material that has been corrugated to obtain a bump foil 100 of a preset shape and size.

In one exemplary embodiment, the execution order of step S30 and step S40 may be changed. Additionally or alternatively, the execution order of step S40 and step S50 may be changed. Although some embodiments have been described, these embodiments are only presented as examples, and are not intended to limit the scope of the present invention. The appended claims and their equivalents are intended to cover all modifications, substitutions and changes that fall within the scope and motivation of the present invention.