Cage for rolling element bearing

Abstract

A cage for a rolling element bearing wherein the cage comprises an irregular cage radius wherein the cage comprises: a first limited region wherein the irregular cage radius remains within a limited range; a first projection range, wherein the irregular cage radius extends beyond a limited range; a second limited region in which the irregular cage radius is maintained within a limited range; and a second projection range, wherein the irregular cage radius extends beyond the limited range.

Description

Technical Field

[0001] The present invention relates to the field of rolling element bearings, and in particular to a retaining frame for a rolling element bearing. The rolling element bearing specifically comprises an outer ring and an inner ring, wherein the inner radius of the outer ring is greater than the outer radius of the inner ring. Background Art

[0002] Rolling element bearings, including roller bearings and ball bearings, are widely used mechanical components used in applications ranging from bicycles to aircraft engines. Generally speaking, this type of bearing is used to separate parts that rotate relative to each other. In most cases, the bearing includes an inner ring and an outer ring, which are separated by a set of rolling elements. The rolling elements allow the inner and outer rings to rotate relative to each other.

[0003] The rolling elements are usually located in a cage, sometimes called a separator or retainer. The cage has holes or pockets for the rolling elements. Usually the cage is guided by an outer ring or an inner ring. The inner and outer rings are sometimes called inner and outer races.

[0004] It has been found that cages can suffer from dynamic instabilities, which can lead to cage failure. These instabilities can include unstable movement of the cage between the inner and outer rings. Failures are particularly likely to occur when operating conditions are demanding, such as when lubrication is difficult or even impossible during use. This is the case, for example, with bearings used in turbo pumps for rocket engines, satellites and space probes. Furthermore, in applications that require high rotational speeds, dynamic instabilities can occur more frequently and lead to failures. Failures and misbehavior have been reported in such projects, where the failure of a relatively small component can have huge consequences for a very expensive project. However, cage failures due to instabilities have also been reported in more traditional applications such as automotive, machining and aviation.

[0005] Although the cage instability problem has long been known and has been widely reported and studied in the literature, no satisfactory solution has yet been proposed. Summary of the invention

[0006] This object is achieved by a cage for a rolling element bearing, wherein the cage comprises an irregular cage radius, wherein the irregular cage radius is

[0007] an outer cage radius, which defines the outer circumference of the cage, and / or

[0008] The inner cage radius, which defines the inner circumference of the cage,

[0009] The retaining frame comprises:

[0010] a first finite region, where the irregular cage radius remains within a finite range between a lower limit and an upper limit,

[0011] a first raised region, wherein the cage includes at least one point where the irregular cage radius extends outside the limited range, wherein the first raised region is circumferentially adjacent to the first limited region;

[0012] a second limited region, wherein the irregular cage radius is maintained within a limited range, wherein the second limited region is adjacent to the first protruding region in a circumferential direction;

[0013] A second raised area, wherein the cage comprises at least one point where the irregular cage radius extends outside the limited range, wherein the second raised area is circumferentially adjacent to the second limited area and the first limited area is circumferentially adjacent to the second raised area.

[0014] The present invention therefore relates to a cage for a rolling element bearing. The rolling element bearing may be, for example, a roller bearing or a ball bearing. The rolling element bearing may be configured to be used with or without lubrication. Preferably, the rolling element bearing has an outer ring and an inner ring, wherein the inner radius of the outer ring is greater than the outer radius of the inner ring. Thus, when viewed in a radial direction, the outer ring is larger than the inner ring. In other words, the rolling element bearing is not a so-called thrust bearing or the like. For example, the rolling element bearing is configured to support radial loads. The bearing may be, for example, a deep groove ball bearing. However, the bearing may also be an angular contact bearing.

[0015] The cage can be configured to be guided by the outer ring of the rolling element bearing or the inner ring of the rolling element bearing. The cage may include a plurality of recesses for the rolling elements. The recesses may be arranged in a single row or in multiple rows, for example, in two rows. The recesses may be closed (for example, the cage is a solid cage), but the recesses may also be open (for example, the cage is a crown cage). The cage may be made of any suitable material, such as a polymer, a composite material (such as fiberglass and additional resin), a metal (such as steel or brass). The cage may be of any type, such as a stamped cage, an integral cage or a pin cage. The cage may be integral or made of multiple parts, such as two parts. The cage may be a solid cage. The cage may be a crown cage.

[0016] For example, the cage may be considered to include an outer cage radius and an inner cage radius. The outer cage radius defines the outer circumference of the cage and the inner radius defines the inner circumference. For example, the cage thickness may be defined between the inner cage radius and the outer cage radius, for example in the radial direction. The width of the cage may optionally be defined in the longitudinal direction. It should be understood that the radius may not be constant over the width when viewed in the longitudinal direction, for example because recesses are provided for rolling elements. In the context of the present invention, the recesses may be ignored when determining the inner cage radius and the outer cage radius.

[0017] At least one of the inner cage radius and the outer cage radius is an irregular cage radius. Irregular in this context means that the corresponding cage radius is not constant when viewed from the corresponding circumference. It should be understood that although the cage is not completely annular (because at least one of the inner radius and the outer radius is not completely circular), the radius is intended in this context to mean the distance between a given point on the inner circumference or the outer circumference, respectively, and the center point of the cage. It is possible that one of the inner and outer cage radii is an irregular cage radius, or both are irregular cage radii.

[0018] When viewed along the circumferential direction (i.e., the angular direction), the retainer can be divided into four regions, including a first limited region adjacent to a first protruding region. The first protruding region is in turn adjacent to a second limited region. The second limited region is in turn adjacent to the second protruding region. The second protruding region is finally adjacent to the first limited region. Therefore, these four regions cover the entire circumference of the retainer, and there are no other regions.

[0019] A limited range is defined between the lower limit and the upper limit, wherein the lower limit may be less than or equal to the upper limit. In the first limited area and the second limited area, the radius of the irregular cage is maintained within a limited range. It is worth noting that the radius of the irregular cage can be varied within a limited range as long as it does not exceed the lower limit and the upper limit.

[0020] In the first protrusion area and the second protrusion area, the irregular cage radius extends outside the limited range. That is, the irregular cage radius is either greater than the upper limit or less than the lower limit. Preferably, the irregular cage radius extends outside the limited range in the first protrusion area and the second protrusion area in the same manner. That is, the irregular cage radius is either greater than the upper limit in the first protrusion area and the second protrusion area, or less than the lower limit in the first protrusion area and the second protrusion area. For example, if the irregular cage radius is an outer cage radius, the irregular cage radius is greater than the upper limit of at least one point in the first protrusion area and the second protrusion area. For example, if the irregular cage radius is an inner cage radius, the irregular cage radius is less than the lower limit of at least one point in the first protrusion area and the second protrusion area. The irregular cage radius extends outside the limited range at one or more points (or positions) in the first and second protrusion areas, wherein the irregular cage radius has the possibility of returning to the limited area between the two points (or positions) where it extends outside the limited range.

[0021] The inventors have found that advantageously, having exactly two raised areas and two limited areas reduces the instability of the cage and, therefore, the failure rate. In theory, this is because the raised areas determine the contact positions that can be made between the cage and the outer or inner ring when instability occurs. Thus, the possible contact points between the cage and the respective ring are predefined in different areas. When contact is made, the raised areas center the cage backwards, thereby reducing any instability. In contrast, when a cage without raised areas is used (i.e., when the cage has only constant inner and outer radii), the entire circumference can be a contact point. This makes contact unpredictable and causes the cage to "bounce" when contact occurs at different contact points. On the other hand, if more than two raised areas are used, the advantages of the invention are also not achieved. Presumably, this is because in these cases more possible contact points are generated, which are distributed over the circumference of the cage, which in turn causes the cage to "bounce" and contact to occur unpredictably at different contact points.

[0022] In an embodiment, the first limited area covers a circumferential area of ​​at least 45 degrees, such as at least 60 degrees. In an embodiment, the second limited area covers a circumferential area of ​​at least 45 degrees, such as at least 60 degrees. The inventors have found that if the first limited area and the second limited area are too small, and therefore the first protruding area and the second protruding area are too large, the cage may still experience unstable movement.

[0023] In an embodiment, the first limited area covers a circumferential area of ​​at least 90 degrees, such as at least 120 degrees, such as at least 130 degrees, such as at least 150 degrees. In an embodiment, the second limited area covers a circumferential area of ​​at least 90 degrees, such as at least 120 degrees, such as at least 150 degrees. The inventors have found that if the first and second limited areas together cover more than half of the circumference of the cage, the possible contact points between the cage and the corresponding ring will be reduced so much that any "bounce" effect is almost eliminated.

[0024] In an embodiment, the first limited area and the second limited area are larger than the first protruding area and the second protruding area. That is, the first limited area is larger than the first protruding area, and larger than the second protruding area. The second limited area is also larger than the first protruding area, and larger than the second protruding area. The inventors have found that this further reduces the chance of unstable movement of the cage.

[0025] In an embodiment, the lower limit of the limited range is less than the standard radius by the limited range deviation, and the upper limit of the limited range is greater than the standard radius by the limited range deviation. Thus, the limited range is defined as "around" the standard radius. Within the limited area, the range by which the irregular cage radius deviates from the standard radius in either direction (radially inward or radially outward) does not exceed the limited range deviation. In the protrusion area, the range by which the irregular cage radius deviates from the standard radius exceeds the limited range deviation.

[0026] Optionally, the standard radius is the average value of the irregular cage radii. For example, the average value is the average value of the radii observed over the entire circumference, i.e. the arithmetic mean.

[0027] Optionally, the standard radius is the radius of the cage in a conventional cage design.

[0028] In an embodiment, the irregular cage radius is not constant in the first limited area and / or the second limited area when viewed in the circumferential direction. Therefore, the irregular cage radius may vary in the first limited area and / or the second limited area, but still within a limited range. The lower limit of the limited range is less than the upper limit. The inventors have found that, advantageously, these embodiments further reduce dynamic instability.

[0029] In an embodiment, the first raised area and the second raised area are symmetrical, and optionally, the first limited area and the second limited area are also symmetrical. Symmetry may be advantageous for production and rotational imbalance during limited use. In addition, symmetry of possible contact points between the cage and the corresponding ring further reduces instability. Symmetry may, for example, be symmetry with respect to a reflection line, wherein the reflection line extends through a center point of the cage, wherein the reflection line may, for example, be a center line. Symmetry may, for example, be symmetry with respect to a reflection point, wherein the reflection point may be a center point of the cage. The cage may also be rotationally symmetrical when the cage is rotated 180 degrees. It is worth noting that in practice, slight deviations from the symmetry may occur, for example within manufacturing tolerances.

[0030] In an embodiment, an upper limit and a lower limit of the limited area are located between an outer radius of the inner ring and an inner radius of the outer ring.

[0031] For example, when the irregular cage radius is the outer cage radius, the irregular cage radius may exceed the upper limit in the protrusion area. In this case, the lower limit can be selected according to the thickness of the cage, the outer radius of the inner ring of the rolling element bearing, and the space required between the cage and the inner ring. This is actually very similar to the design of the conventional cage. The distance between the lower limit and the inner radius of the outer ring can be divided into three areas, including a first area between the lower limit and the upper limit, a second area between the upper limit and the protrusion limit, and a third area between the protrusion limit and the inner radius of the outer ring. The protrusion limit is the maximum radius of the irregular cage radius in the first protrusion area and the second protrusion area. For example, the first area can be defined to allow the cage to have a certain thickness, thereby ensuring that the cage has sufficient strength, similar to the conventional cage design. For example, the third area can be defined by the space required between the cage and the outer ring to allow movement, which is also similar to the conventional cage design. The size of the second area can be equal to the size of the third area, for example. In some embodiments, the second area and the third area are several orders of magnitude smaller than the first area.

[0032] For example, when the irregular cage radius is the inner cage radius, the irregular cage radius can be smaller than the lower limit in the protrusion area. In this case, the upper limit can be selected according to the thickness of the cage, the inner radius of the outer ring of the rolling element bearing, and the space required between the cage and the outer ring. This is actually very similar to the design of the conventional cage. The distance between the upper limit and the outer radius of the inner ring can be divided into three areas, including a first area between the upper limit and the lower limit, a second area between the lower limit and the protrusion limit, and a third area between the protrusion limit and the outer radius of the inner ring. In this case, the protrusion limit is the minimum radius of the irregular cage radius in the first protrusion area and the second protrusion area. For example, the first area can be defined to allow the cage to have a certain thickness, thereby ensuring that the cage has sufficient strength, similar to the conventional cage design. The third area can be defined, for example, by the space required between the cage and the inner ring to allow movement, similar to the conventional cage design. The size of the second area can be equal to the size of the third area, for example. In some embodiments, the second area and the third area are several orders of magnitude smaller than the first area.

[0033] In an embodiment, the irregular cage radius is configured such that contact between the irregular cage radius and the outer ring or the inner ring is only possible in the first and second protrusion areas, for example only at the point where the irregular cage radius extends outside the limited range. In particular, the upper and lower limits of the limited range may be defined accordingly, optionally depending on the protrusion limits of the irregular cage radius in the first and second protrusions and the inner radius of the outer ring or the outer radius of the inner ring.

[0034] For example, if the irregular cage radius is the outer cage radius, the cage can contact the outer ring in the first protrusion area and the second protrusion area, and the cage cannot contact the outer ring in the first limited area and the second limited area. If the irregular cage radius is the inner cage radius, the cage can contact the inner ring in the first protrusion area and the second protrusion area, and the cage cannot contact the inner ring in the first limited area and the second limited area.

[0035] In an embodiment, the first protrusion area and / or the second protrusion area each include a single protrusion extending beyond the limited range. Therefore, there is exactly one protrusion extending beyond the limited range of the first protrusion area and / or the second protrusion area. The protrusion may, for example, define a protrusion limit. These embodiments may be relatively simple to produce. The protrusion may cover the entire protrusion area, or may be smaller than the protrusion area. The protrusion may cause a portion of the protrusion area to have a constant irregular cage radius, for example, having a conical shape with a platform. The protrusion may also have an inconstant cage radius, for example, having a conical shape with a (rounded) tip.

[0036] In an embodiment, the first protrusion area and / or the second protrusion area each include a plurality of protrusions extending beyond the limited range, for example at least two, three, four or five protrusions. The protrusions extending farthest beyond the limited range may define the protrusion limit. These embodiments may be useful in reducing dynamic instability. The protrusions may cause a portion of the protrusion area to have a constant irregular cage radius, for example having a conical shape with a platform. The protrusions may also have a non-constant cage radius, for example having a conical shape with a (rounded) tip.

[0037] In an embodiment, the irregular cage radius is constant in the first limited area and / or the second limited area. Therefore, the irregular cage radius is the same throughout the first limited area and / or the second limited area. There are no protrusions in these areas. Of course, the cage may still include recesses for rolling elements in this area. These embodiments may be relatively simple to produce. In these embodiments, the upper and lower limits of the limited range may, for example, be equal to each other. It should be understood that even if the cage radius is constant, manufacturing tolerances and / or defects may cause slight deviations in the cage radius.

[0038] In an embodiment, the cage comprises a plurality of recesses for rolling elements. The recesses may, for example, be arranged in a single row or in a double row. Optionally, in addition to the recesses, the irregular radius extends beyond a limited range at any point of the cage when viewed along the width in the longitudinal direction. Optionally, the irregular radius is constant at any point of the cage when viewed along the width in the longitudinal direction.

[0039] In an embodiment, the irregular cage radius is a contact cage radius. For example, when the rolling element bearing is an angular contact bearing, it is possible that only a portion of the outer surface can contact the outer ring; or only a portion of the inner surface can contact the inner ring. In this case, the irregular cage radius refers to the portion of the outer surface or the inner surface. The radius of the other portion of the outer surface or the inner surface has no effect on the contact between the cage and the ring, respectively, and therefore does not necessarily have to be defined according to the limited area and the protruding area defined herein.

[0040] In an embodiment, the retainer is integral. Thus, the retainer is made of a unitary element. The retainer may be machined, molded or 3D printed, for example.

[0041] In an embodiment, the cage is made of two elements connected to each other (e.g. riveted). For example, when viewed in the longitudinal direction, the cage can be divided into two elements, each element comprising half of a recess. During installation, the half recess can be arranged around the rolling element, and the two elements can be connected to each other to form a recess around the rolling element and form the cage.

[0042] In an embodiment, the retainer includes an open recess. For example, the retainer can be a crown retainer. Crown retainers are used in a variety of applications, including, for example, electric motors. As electric vehicles become more popular, a retainer that can withstand high loads while remaining economical is needed, such as can be achieved by a crown retainer implemented according to the present invention.

[0043] In an embodiment, the protrusion is an element arranged on the retaining frame. For example, the protrusion is riveted, glued or screwed.

[0044] In an embodiment, the protrusion has any one of a circular profile, a rectangular profile, a square profile, an oval profile, and an elliptical profile.

[0045] In an embodiment, the cage is configured for use in a non-lubricated rolling element bearing or a marginally lubricated rolling element bearing. In particular, in applications where lubrication is difficult or impossible to provide, cage failures often occur, and the use of the cage of the present invention can advantageously reduce such failures. In this technical field, marginal lubrication refers to the situation where only a small amount of lubricant is provided in the bearing. Therefore, the balls and rollers are not completely separated by a lubricating film.

[0046] In an embodiment, the irregular cage radius is an outer cage radius, wherein in the first protruding area and the second protruding area, the irregular cage radius exceeds the limited range by exceeding the upper limit. Optionally, the cage is configured to be guided by the outer ring of the rolling element bearing. When the cage is guided by the outer ring, any contact between the cage and the rolling element bearing occurs on the outer ring. Therefore, the protruding area can be arranged to extend beyond the upper limit to ensure that the cage contacts one of the protruding areas.

[0047] In these embodiments, the cage may also be described as: a cage for a rolling element bearing, wherein the cage is configured to be guided by an outer ring of the rolling element bearing, wherein the cage includes an outer cage radius defining an outer circumference of the cage, wherein the cage includes: a first limited area, wherein the outer cage radius remains within a limited range between a lower limit and an upper limit; a first raised area, wherein the cage includes at least one point where the outer cage radius exceeds the upper limit, wherein the first raised area is adjacent to the first limited area in a circumferential direction; a second limited area, wherein the outer cage radius remains within a limited range, wherein the second limited area is adjacent to the first raised area in a circumferential direction; a second raised area, wherein the cage includes at least one point where the outer cage radius exceeds the upper limit, wherein the second raised area is adjacent to the second limited area in a circumferential direction, and the first limited area is adjacent to the second raised area in a circumferential direction. It should be understood that any features or embodiments described herein may be applied to the cage.

[0048] For example, when the cage is guided by the outer ring, the dimensions of the cage, inner ring and outer ring are such that the outer circumference of the cage can only contact the inner circumference of the outer ring. The inner circumference of the cage cannot contact the outer circumference of the inner ring.

[0049] In an embodiment, the irregular cage radius is an inner cage radius, wherein in the first protrusion area and the second protrusion area, the irregular cage radius exceeds the limited range by being less than the lower limit. Optionally, the cage is configured to be guided by the inner ring of the rolling element bearing. When the cage is guided by the inner ring, any contact between the cage and the rolling element bearing occurs on the inner ring. Therefore, the protrusion area can be arranged to be less than the lower limit to ensure that the cage contacts one of the protrusion areas.

[0050] In these embodiments, the cage may also be described as: a cage for a rolling element bearing, wherein the cage is configured to be guided by an inner ring of the rolling element bearing, wherein the cage includes an inner cage radius that defines an inner circumference of the cage, wherein the cage includes: a first limited area, wherein the inner cage radius remains within a limited range between a lower limit and an upper limit; a first raised area, wherein the cage includes at least one point where the inner cage radius is less than the lower limit, wherein the first raised area is adjacent to the first limited area in a circumferential direction; a second limited area, wherein the inner cage radius remains within a limited range, wherein the second limited area is adjacent to the first raised area in a circumferential direction; a second raised area, wherein the cage includes at least one point where the inner cage radius is less than the lower limit, wherein the second raised area is adjacent to the second limited area in a circumferential direction, and the first limited area is adjacent to the second raised area in a circumferential direction. It should be understood that any features or embodiments described herein may be applied to the cage.

[0051] For example, when the cage is guided by the outer ring, the dimensions of the cage, inner ring and outer ring are such that the inner circumference of the cage can only contact the outer circumference of the inner ring. The outer circumference of the cage cannot contact the inner circumference of the outer ring.

[0052] The present invention also relates to a rolling element bearing, comprising a cage according to any of the embodiments described herein. Optionally, the rolling element bearing is a rolling bearing, such as a cylindrical rolling bearing, a self-aligning rolling bearing or a tapered rolling bearing. Optionally, the rolling element bearing is a ball bearing, such as a single-row ball bearing, a double-row ball bearing, a deep groove ball bearing, an angular ball bearing, a self-aligning ball bearing, a three-point contact ball bearing, a four-point contact ball bearing, etc. Optionally, the rolling element bearing has an outer ring and an inner ring, wherein the inner radius of the outer ring is greater than the outer radius of the inner ring. That is, the rolling element bearing is not a so-called thrust bearing or similar bearing.

[0053] The invention also relates to a satellite, a space probe, a turbo pump (e.g. for a rocket engine), a turbo reactor (e.g. for an aircraft), a space launcher or an electric vehicle, comprising a rolling element bearing and / or a cage according to any of the embodiments described herein. These systems use cages and rolling element bearings under harsh conditions, such as difficult or impossible lubrication and / or vacuum conditions, which may lead to cage failure. Furthermore, cage failures in these expensive and long-term projects may have serious consequences. The invention advantageously reduces cage failures.

[0054] The present invention also relates to a method. Although the method may relate to a cage and / or rolling element bearing according to the present invention, the cage and / or rolling element bearing and the method are not limited thereto. Unless otherwise expressly defined, the features explained herein with respect to the cage and / or rolling element bearing have the same meaning for the method. The features explained with reference to the cage and / or rolling element bearing can be appropriately modified and applied to the method to achieve similar advantages.

[0055] The object of the invention can be achieved, for example, by a method for designing a cage for a rolling element bearing, wherein, optionally, the rolling element bearing has an outer ring and an inner ring, wherein the inner radius of the outer ring is greater than the outer radius of the inner ring, wherein, optionally, the cage is according to any of the preceding claims, wherein the method comprises the following steps:

[0056] ·Define the radius of the irregular cage, where the radius of the irregular cage is

[0057] The outer cage radius, which defines the outer circumference of the cage, and /

[0058] or

[0059] The inner cage radius, which defines the inner circumference of the cage,

[0060] Design of cages, including

[0061] a first limited region, wherein the irregular cage radius remains within a limited range between a lower limit and an upper limit, wherein for example the first limited region covers a circumferential area of ​​at least 90 degrees;

[0062] a first raised region, wherein the cage includes at least one point where the irregular cage radius extends outside the limited range, wherein the first raised region is circumferentially adjacent to the first limited region;

[0063] a second limited area, wherein the irregular cage radius is maintained within a limited range, wherein the second limited area is adjacent to the first protruding area in a circumferential direction; wherein for example the second limited area covers a circumferential area of ​​at least 90 degrees;

[0064] A second raised area, wherein the cage comprises at least one point where the irregular cage radius extends outside the limited range, wherein the second raised area is circumferentially adjacent to the second limited area and the first limited area is circumferentially adjacent to the second raised area. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] Exemplary embodiments of the present invention are described using figures. It should be understood that these figures are only examples of how to implement the present invention and are not intended to be interpreted as limiting the scope of the present invention and the claims. The same features in the figures are represented by the same figure numerals. In the figures:

[0066] Figure 1a : schematically illustrates a rolling element bearing;

[0067] Figure 1b : Schematically shows Figure 1a The cross section AA shown in ;

[0068] Figure 1c : schematically illustrates a rolling element bearing;

[0069] Figure 1d : Schematically shows Figure 1c A cross section of a rolling element bearing shown in;

[0070] Figure 2a : schematically shows a side view of a retainer according to the present invention;

[0071] Figure 2b : Schematically shows Figure 2a A magnified view of detail A in FIG.

[0072] Figure 2c-2d : A further view of the cage is schematically shown;

[0073] Figure 3a : Schematically shows how to design the cage when guided by the outer ring;

[0074] Figure 3b : Schematically shows how to design the cage when guided by the inner ring;

[0075] Figure 4a-4b : An example of a cage is schematically shown;

[0076] Figure 4c-4d : schematically shows an example of an irregular cage in which the radius of the cage is not constant in the first and second limited areas;

[0077] Figure 5a-5c : schematically shows a crowned cage with protrusions that do not extend across the entire width of the cage;

[0078] Figure 5d : schematically shows a crowned cage having protrusions extending over the entire width of the cage;

[0079] Figure 6a-6d : Schematically shows that the irregular cage radius can be the contact cage radius.

[0080] Figure 1a to Figure 1d A rolling element bearing 1 is shown, wherein Figure 1b Shows Figure 1b The cross section AA shown in Figure 1d Shows Figure 1c These figures show a rolling element bearing 1 in general and according to the prior art; however, from the description herein, a person skilled in the art will easily understand that the rolling element bearing 1 can be adapted according to the present invention by providing a cage according to the present invention. DETAILED DESCRIPTION

[0081] Figure 1a-1d The rolling element bearing 1 shown is a ball bearing that includes a plurality of balls 4 as rolling elements. The balls 4 enable an outer ring 2 and an inner ring 3 (sometimes also referred to as an outer raceway 2 and an inner raceway 3) to move relative to each other. In this way, a first element connected to the outer ring 2 can rotate relative to a second element connected to the inner ring 3. A cage 5 is provided, which has a plurality of recesses for accommodating and positioning the balls 4. Figure 1b It is shown that, in this example, the cage 5 is guided by the outer ring 2 , although the cage 5 can also be guided by the inner ring 3 .

[0082] During use, the cage 5 may rotate at high speeds (high rotational speed). This may lead to dynamic instabilities of the cage 5 and ultimately to (mechanical) failure. Failures may occur more easily in applications where only a small amount of lubrication is available or even no lubrication is available. Failure of the cage 5 may render the entire rolling element bearing 1 unusable. This is particularly a big problem when the rolling element bearing 1 is not easy to replace, for example because the rolling element bearing 1 is located in equipment in outer space, such as satellites or space probes. In other applications as well, such failures may have huge economic consequences, for example when a rolling element bearing 1 fails in an aircraft.

[0083] Figure 2a to Figure 2dAn example of a cage 10 according to the invention is shown, which can be used to reduce dynamic instabilities and / or failures caused thereby. In this example, the cage 10 is configured to be guided by the outer ring of a rolling element bearing 1. The cage 10 comprises an inner cage radius 11 defining an inner circumference 12 and an outer cage radius 13 defining an outer circumference 14. In this example, the inner cage radius 11 is regular and constant, in that it is equal over the entire inner circumference 12. On the other hand, the outer cage radius 13 is an irregular cage radius 13. The irregularity of the irregular cage radius 13 is in this case manifested as a first protrusion 31 and a second protrusion 32, wherein the outer cage radius 13 is larger.

[0084] Figure 2a The detail A in FIG. 1 comprises a first protrusion 31 which is formed at Figure 2b is displayed enlarged. Figure 2b A lower limit 25 and an upper limit 26 are also marked in FIG. A limited range can be defined between the lower limit 25 and the upper limit 26. The first protrusion 31 extends beyond the limited range by exceeding the upper limit 26. Figure 2a It is not clearly indicated in the figure, but it is obvious that the second protrusion 32 also exceeds the upper limit 26. Between the first protrusion 31 and the second protrusion 32, the irregular cage radius 13 is maintained within a limited range.

[0085] Based on this, the cage 10 can be divided into four areas, such as Figure 2a As shown: a first limited area 21, a first protruding area 22, a second limited area 23 and a second protruding area 24. In the first limited area 21 and the second limited area 23, the irregular cage radius 13 is maintained within a limited range between a lower limit 25 and an upper limit 26. In the first protruding area 22 and the second protruding area 24, the irregular cage radius 13 at least once extends outside the limited range, where there are first protrusions 31 and second protrusions 32.

[0086] When viewed in the circumferential direction 41, the regions 21, 22, 23, 24 are adjacent to each other and constitute the entire cage 10. The cage 10 can therefore be divided precisely into these four regions 21, 22, 23, 24. It has been found that dynamic instabilities can be reduced if there are exactly two raised regions 22, 24 and two limited regions 21, 23 in between. If during use the cage 10 becomes unstable and deviates from its desired position, it is usually the first protrusion 31 or the second protrusion 32 that contacts the outer ring of the rolling element bearing. This predefined narrow contact surface reduces the instability of the cage.

[0087] exist Figure 2aIt can also be seen that, optionally, the first protruding area 22 and the second protruding area 24 are symmetrical to each other, and the first limited area 21 and the second limited area 23 are also symmetrical to each other. In this case, the center point 16 of the holder 10 is the reflection point, but it can be seen that multiple reflection lines can also be drawn through the center point 16.

[0088] The first limited area 21 and the second limited area 23 are larger than the first protruding area 22 and the second protruding area 24. Specifically, when viewed along the circumferential direction 41, the first limited area 21 and the second limited area 23 each cover a circumferential area larger than 90 degrees, in this case even larger than 120 degrees.

[0089] exist Figure 2c-2d As can be seen most clearly in the example, the cage 10 includes a plurality of recesses 15 for rolling elements. In this case, since the rolling elements are balls and the cage is solid, the recesses 15 define circular openings, so that the cage 10 can be used for ball bearings. However, the present invention can be applied in a similar manner to other types of rolling element bearings, such as bearings with cylindrical rolling elements. The present invention can also be applied to crowned cages. Although the cage 10 in the example shown includes a single row of recesses 15, the cage 10 can also include multiple rows of recesses 15.

[0090] like Figure 2c As shown, the width 17 of the cage 10 can be defined in the longitudinal direction 42. In the example shown, the first protrusion 31 and the second protrusion 32 extend over the entire width 17 of the cage 10, except for the groove 31a for the pocket 15. However, the first protrusion 31 and / or the second protrusion 32 can also be arranged only over a portion of the width 17, for example half of the width 17. This can be determined, for example, depending on how the outer ring guides the cage 10. For example, the irregular cage radius may be a contact cage radius and only relate to a portion of the width 17, as further explained below.

[0091] In the example shown, the irregular cage radius and the height of the first and second protrusions 31, 32 are constant when viewed over the width 17, except of course for the recesses 15. However, this is not essential.

[0092] It is worth noting that, although in this example, the inner cage radius 11 is regular and constant, this is not required. For example, the thickness of the cage 10 (defined between the outer circumference 14 and the inner circumference 12) can be constant, so that the inner cage radius 11 has the same irregularity as the outer cage radius 13.

[0093] Figure 3aIt is shown how to design a cage 10, for example, for a cage 10 configured to be guided by an outer ring of a rolling element bearing. Thus, in this case, the irregular cage radius may be an outer cage radius. A lower limit 25 and an upper limit 26 are indicated. In the first limited area 21 and the second limited area 23, the irregular cage radius remains within the limits between the lower limit 25 and the upper limit 26. Thus, the irregular cage radius remains within Figure 3a , and for example will not exceed the area indicated by d. However, it is worth noting that the limited range in area a still allows the irregular cage radius to be non-constant in the first limited area 21 and the second limited area 23. In fact, such an implementation can provide additional advantages.

[0094] In the first protrusion area 22 and the second protrusion area 24, the irregular cage radius exceeds the upper limit 26 and is therefore located at at least one point in the area indicated by b. However, it is worth noting that at other points in the first protrusion area 22 and the second protrusion area 24, the irregular cage radius may still be within the limited range indicated by the area c.

[0095] therefore, Figure 3a An example is shown in which the irregular cage radius is the outer cage radius, and in the protrusion areas 22, 24 the irregular cage radius exceeds the upper limit 26. In this case, the lower limit 25 can be selected according to the thickness of the cage 10, the outer radius of the inner ring of the rolling element bearing, and the required space between the cage 10 and the inner ring. This is actually very similar to the design of a conventional cage.

[0096] Figure 3a Also shown is the inner radius 51 of the outer ring of the rolling element bearing, and the protrusion limit 27, which shows the maximum limit of the irregular cage radius in the first protrusion area 22 and the second protrusion area 24. The protrusion limit 27 is preferably a little smaller than the inner radius 51 to ensure that there is a certain space between the cage 10 and the outer ring (when all parts are correctly centered) to avoid unnecessary friction during rotation. The distance between the protrusion limit 27 and the inner radius 51 can also be selected similar to the design of a conventional cage.

[0097] As an example, the distance between the lower limit 25 and the protrusion limit 27 can be divided into three regions. The first region (denoted as regions a and c) defines a limited range between the lower limit 25 and the upper limit 26. The second region is defined between the upper limit 26 and the protrusion limit 27, where the irregular cage radius can only extend in the protrusion area 22, the protrusion area 24 (denoted by region b), but not in the limited area 21, the limited area 23 (denoted by region d). The third region is defined between the protrusion limit 27 and the inner radius 51, and the irregular cage radius does not extend to this region.

[0098] For example, the first region (i.e., the distance between the upper limit 26 and the lower limit 25) can be selected to ensure that the thickness of the cage 10 in the limited area 21, the limited area 23 provides sufficient strength. This may depend on the application, but is generally similar to conventional cage designs. The third region (i.e., the distance between the protrusion limit 27 and the inner radius 51) can be selected to leave enough space between the cage 10 and the outer ring during use. The second region (i.e., the distance between the upper limit 26 and the protrusion limit 27) can be selected to be equal to the third region. Although not shown to scale in the figure for clarity, in reality the first region may be several orders of magnitude larger than the second and third regions.

[0099] As another example, the upper limit 26 can be selected based on the design of the inner radius 51 and the irregular cage radius in the protrusion areas 22, 24. The goal of this example is that any contact between the outer ring and the cage can only occur through the protrusions in the protrusion areas 22, 24. It should be understood that various designs are possible and those skilled in the art can easily implement these designs according to actual conditions.

[0100] As another example, a standard radius may be defined. The upper limit 26 and the lower limit 25 may then be selected as a limited range deviation from the standard radius. Thus, the upper limit 26 is larger than the standard radius by a limited range deviation, and the lower limit 25 is smaller than the standard radius by a limited range deviation. The standard radius may, for example, be defined as an average value of the irregular cage radii.

[0101] Figure 3b In a similar manner it is shown how to design the cage 10, for example, for a cage 10 configured to be guided by the inner ring of a rolling element bearing. Thus, in this case, the irregular cage radius may be an inner cage radius. In the first limited area 21 and the second limited area 23, the irregular cage radius remains within a limited range between a lower limit 25 and an upper limit 26, corresponding to Figure 3a In the first protruding area 22 and the second protruding area 24, the irregular cage radius becomes smaller than the lower limit 25 at at least one point to extend to the area shown in b.

[0102] therefore, Figure 3b An example is shown in which the irregular cage radius is the inner cage radius, and the irregular cage radius in the protrusion area 22, the protrusion area 24 is less than the lower limit 25. In this case, the upper limit 26 can be selected according to the thickness of the cage 10, the inner radius of the outer ring of the rolling element bearing, and the required space between the cage 10 and the outer ring. This is actually very similar to the design of a conventional cage.

[0103] Figure 3b Also shown is the outer radius 52 of the inner ring of the rolling element bearing, and the protrusion limit 28 showing the minimum limit of the irregular cage radius in the first protrusion area 22 and the second protrusion area 24. The distance between the protrusion limit 28 and the outer radius 52 may also be selected similar to the design of a conventional cage to avoid unnecessary friction.

[0104] As another example, the distance between the upper limit 26 and the outer radius 52 can be divided into three regions, and the lower limit 25 can be defined as the middle position between the upper limit 26 and the protrusion limit 28. Figure 3a The same reasoning explained in applies, mutatis mutandis.

[0105] As another example, lower limit 25 can be selected based on the design of outer radius 52 and irregular cage radius in protrusion areas 22 and 24 so that any contact between the inner ring and the cage can only occur through the protrusions in protrusion areas 22 and 24.

[0106] As another example, a standard radius may be defined. An upper limit 26 and a lower limit 25 may then be selected as a limited range deviation from the standard radius. Thus, the upper limit 26 exceeds the standard radius by a limited range deviation, and the lower limit 25 is smaller than the standard radius by a limited range deviation. The standard radius may, for example, be defined as an average value of irregular cage radii.

[0107] Figures 4a-4d Examples of possible embodiments of a cage 10 according to the invention are shown. These examples relate to cages 10 in which the irregular cage radius 13 is an outer cage radius 13 which extends beyond the limited range by exceeding the upper limit 26. However, it should be understood that similar embodiments are applicable to cages having an inner cage radius as the irregular cage radius.

[0108] Figure 4a An example is shown in which the irregular cage radius 13 is constant in the first limited area 21 and the second limited area 23. In the first protrusion area 22 and the second protrusion area 24, the irregular cage radius 13 extends beyond the limited range with a single protrusion 61, 62. The first protrusion 61 includes a first platform 62, and the second protrusion 63 includes a second platform 64, in which case there are straight extensions 61, 63 from the limited range toward the platform 62, 64.

[0109] Figure 4bAn example is shown in which the irregular cage radius 13 is also constant in the first limited area 21 and the second limited area 23. In this case, the first protrusion area 22 includes a plurality of protrusions 71, and the second protrusion area 24 also includes a plurality of protrusions 72. In this case, seven protrusions 71, 72 are provided each time, but other numbers of protrusions 71, 72 are also possible. Between two consecutive protrusions 71 or protrusions 72, the irregular cage radius 13 returns to the limited range.

[0110] Figure 4c An example is shown in which the irregular cage radius 13 is not constant in the limited areas 21, 23. It can be seen that the first limited area 21 includes a plurality of bumps 83 and the second limited area 23 also includes a plurality of bumps 84. It has been found that this can further reduce the dynamic instability of the cage 10. Figure 4c It is further shown that the first protrusion region 22 includes a single first protrusion 81, and the second protrusion region 24 includes a single second protrusion 82. In this example, the first protrusion 81 and the second protrusion 82 do not include a platform, but have a conical shape with a pointed end.

[0111] Figure 4d An example is shown in which the irregular cage radius 13 has an elliptical shape. Therefore, the irregular cage radius 13 is not constant in the limited areas 21 , 23 , and has a single protrusion 91 , 92 in both the first protrusion area 22 and the second protrusion area 24 .

[0112] Figures 4a-4d It is also shown that the first limited area 21 and the second limited area 23 are larger than the first protruding area 22 and the second protruding area 24. When viewed from the circumferential direction, the limited area 21 and the limited area 23 are larger than 90 degrees, or even larger than 120 degrees. It can also be seen that the protruding area 22 and the protruding area 24 in the embodiment are symmetrical to each other, and the limited area 21 and the limited area 23 are also symmetrical to each other.

[0113] Although the foregoing figures show a solid retainer with a closed recess 15, it will be appreciated that the present invention is also applicable to Figure 5a , Figure 5b and Figure 5cThe crowned cage 101 shown. The crowned cage 115 has an open recess 115. This is advantageous, for example, for arranging the cage 101 on a rolling element such as a ball by a snap-fit ​​action. This allows the production of a relatively cheap cage. Such a cage can be used, for example, in electric vehicles, such as vehicles with an electric motor, such as an electric vehicle (EV) or a hybrid electric vehicle (HEV or PHEV). The present invention can increase the stability of such a cage 101 while still keeping the cost relatively low. The figures show a first protrusion 131 (part of the first protrusion area) and a second protrusion 132 (part of the second protrusion area) in the cage 101.

[0114] exist Figure 5a to Figure 5c , an exemplary embodiment is shown in which the projections 131 , 132 do not extend over the entire width of the holder 101 . Figure 5d A cage 301 is shown, again as a crown-shaped cage 301 , but in this case the projections 331 extend over the entire width of the cage 301 .

[0115] Figures 6a to 6d It is shown that the irregular cage radius 205b can be a contact cage radius 205b within the scope of the present invention. Figure 6a shows a cross section of a bearing 201, Figure 6b The cage 205 is shown. The figures show an outer ring 202, an inner ring 203, a cage 205 and rolling elements 204. The bearing 201 is an angular contact ball bearing. A first side 205a of the cage 205 is not in contact with either of the rings 202, 203. A second side 205b of the cage 205 is guided by the outer ring 203. In this case, the irregular cage radius 205b is the second side 205b because this part of the cage 205 defines the contact. The radius of the first side 205a is not important and does not need to follow the requirements of the limited area and the protruding area. This is for example in Figure 6c and 6d It is shown in, where Figure 6c Shows Figure 6b The cross section AA shown in Figure 6d Shows Figure 6b Cross section BB shown in .

[0116] Figure 6c An irregular cage radius 205b is shown in the protrusion area. The irregular cage radius 205b extends beyond the limited range. The radius 205a of the first side 205a also extends beyond the limited range and is equal to the irregular cage radius 205b in this section.

[0117] Figure 6dThe irregular cage radius 205b is shown in a limited area. The irregular cage radius 205b is kept within a limited range and is significantly smaller than Figure 6c However, in Figure 6d In the embodiment, the radius 205a of the first side 205a still extends beyond the limited range and is no longer equal to the irregular cage radius 205b in this portion. In other embodiments, the radius 205a can be different from the radius 205b in various ways.

[0118] As required, detailed embodiments of the present invention are described herein; however, it should be understood that the disclosed embodiments are merely examples of the present invention, which can be implemented in various ways. Therefore, the specific structural and functional details disclosed herein should not be understood as limiting, but only as a basis for the claims and as a representative basis for teaching those skilled in the art to practice the present invention in various ways in almost any suitable detailed structure. Not all of the described goals need to be achieved by specific embodiments.

[0119] In addition, the terms and expressions used herein are not intended to limit the present invention, but only to provide an understandable description of the present invention. The words "a", "an" or "an" used herein mean one or more, unless otherwise specified. The terms "multiple", "multiple" or "several" mean two or more than two. The words "include", "comprise", "contain" and "have" have open meanings and do not exclude the presence of additional elements. The figure marks in the claims should not be interpreted as limiting the present invention.

[0120] Even if certain technical features are described in different dependent claims, it is still possible to advantageously use these measures in combination.

Claims

1. A cage (10) for a rolling element bearing (1), wherein: The rolling element bearing comprises an outer ring (2) and an inner ring (3), wherein the inner radius (51) of the outer ring is greater than the outer radius (52) of the inner ring, wherein the cage comprises an irregular cage radius (11, 13), wherein the irregular cage radius is an outer cage radius (13) which defines an outer circumference (14) of the cage, and / or an inner cage radius (11), the inner cage radius (11) defining an inner circumference (12) of the cage, Wherein, the retaining frame comprises: a first limited region (21), wherein the irregular cage radius remains within a limited range between a lower limit (25) and an upper limit (26), wherein the first limited region covers a circumferential area of ​​at least 90 degrees; a first protruding region (22), wherein the retainer includes at least one point where the irregular retainer radius extends outside the limited range, wherein the first protruding region is adjacent to the first limited region in a circumferential direction; a second limited area (23), wherein the irregular retainer radius is maintained within the limited range, wherein the second limited area is adjacent to the first protrusion area in the circumferential direction; wherein the second limited area covers at least 90 degrees of the circumferential area; a second raised area (24), wherein the retainer includes at least one point where the irregular retainer radius extends outside the limited range, wherein the second raised area is circumferentially adjacent to the second limited area, and the first limited area is circumferentially adjacent to the second raised area, The lower limit of the limited range is smaller than a standard radius by a limited range deviation, and the upper limit of the limited range is larger than the standard radius by the limited range deviation, wherein the standard radius is an average value of the irregular cage radii.

2. A cage according to claim 1, wherein the irregular cage radius is configured so that contact between the irregular cage radius and the outer ring or the inner ring, respectively, is possible only in the first protrusion area and the second protrusion area, and only at the point where the irregular cage radius extends outside the limited range.

3. The retainer according to claim 1 or 2, wherein: The irregular cage radius is constant in the first limited area and the second limited area.

4. The retainer according to claim 1 or 2, wherein: When viewed in the circumferential direction, the irregular cage radius is not constant in the first limited area and the second limited area.

5. The retainer according to claim 1 or 2, wherein: The first limited area covers a circumferential area of ​​at least 120 degrees, such as at least 150 degrees; and The second limited area covers a circumferential area of ​​at least 120 degrees, such as at least 150 degrees.

6. A cage according to any preceding claim, wherein the first and second raised areas are symmetrical, and optionally the first and second limited areas are also symmetrical.

7. A cage according to any preceding claim, wherein the first and second raised areas each comprise a single projection (62, 64, 81, 82, 91, 92) extending beyond the limited extent.

8. The retaining frame according to any one of claims 1 to 6, wherein the first protrusion area and the second protrusion area each include a plurality of protrusions (71, 72) extending outside the limited range.

9. A cage according to any preceding claim, wherein the cage is configured for use in a non-lubricated rolling element bearing or a marginally lubricated rolling element bearing.

10. The cage according to any of the preceding claims, wherein the irregular cage radius is the outer cage radius, wherein in the first protruding area and the second protruding area the irregular cage radius exceeds the limited range by exceeding the upper limit.

11. The retainer according to claim 10, wherein: The cage is configured to be guided by the outer ring of the rolling element bearing.

12. The cage according to any one of claims 1 to 9, wherein the irregular cage radius is the inner cage radius, wherein in the first protrusion area and the second protrusion area, the irregular cage radius exceeds the limited range by being smaller than the lower limit.

13. The retainer according to claim 12, wherein: The cage is configured to be guided by the inner ring of the rolling element bearing.

14. A rolling element bearing comprising a cage according to any preceding claim, wherein the rolling element bearing has an outer ring and an inner ring, wherein the inner radius of the outer ring is greater than the outer radius of the inner ring, wherein optionally, the rolling element bearing is one of the following: rolling bearings, such as cylindrical, spherical or tapered rolling bearings; or Ball bearings, such as single-row ball bearings, double-row ball bearings, deep groove ball bearings, angular ball bearings, such as wherein the irregular cage radius is a contact cage radius, self-aligning ball bearings, three-point contact ball bearings, four-point contact ball bearings.

15. A satellite, a space probe, a turbo pump, a space launch vehicle or an electric vehicle comprising a rolling element bearing and / or a cage according to any preceding claim.

16. A method for designing a cage of a rolling element bearing, wherein: The rolling element bearing has an outer ring and an inner ring, wherein the inner radius of the outer ring is greater than the outer radius of the inner ring, wherein, optionally, a cage according to any of the preceding claims, wherein the method comprises the steps of: Define an irregular cage radius, wherein the irregular cage radius is an outer cage radius, which defines the outer circumference of the cage, and / or an inner cage radius, the inner cage radius defining the inner circumference of the cage, Design of cages, including a first limited region, wherein the irregular cage radius remains within a limited range between a lower limit and an upper limit, wherein the first limited region covers a circumferential region of at least 90 degrees; a first protruding region, wherein the retainer includes at least one point where the irregular retainer radius extends outside the limited range, wherein the first protruding region is circumferentially adjacent to the first limited region; a second limited area, wherein the irregular retainer radius is maintained within the limited range, wherein the second limited area is adjacent to the first protrusion area in a circumferential direction; wherein the second limited area covers at least 90 degrees of the circumferential area; a second protruding region, wherein the retainer includes at least one point where the irregular retainer radius extends outside the limited range, wherein the second protruding region is circumferentially adjacent to the second limited region, and the first limited region is circumferentially adjacent to the second protruding region, wherein the lower limit of the limited range is smaller than a standard radius by a limited range deviation, and the upper limit of the limited range is larger than the standard radius by the limited range deviation, wherein the standard radius is an average value of the irregular cage radii.

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