Rolling element bearing cages

Abstract

A cage for a rolling element bearing, the cage having an irregular cage radius, the cage comprising a first confined region where the irregular cage radius remains within the confined range, a first protruding region where the irregular cage radius extends outside the confined range, a second confined region where the irregular cage radius remains within the confined range, and a second protruding region where the irregular cage radius extends outside the confined range.

Description

[Technical Field]

[0001] The present invention relates to the field of rolling element bearings, in particular to a cage for a rolling element bearing, which comprises in particular an outer ring and an inner ring, the inner radius of the outer ring being greater than the outer radius of the inner ring. [Background technology]

[0002] Rolling element bearings, such as roller and ball bearings, are very common machine components and are used in a variety of applications, from bicycles to aircraft engines. Generally, the function of this type of bearing is to separate parts that rotate relative to one another. Often, the bearing consists of an inner ring and an outer ring separated by a set of rolling elements. The rolling elements allow the inner and outer rings to rotate relative to one another.

[0003] The rolling elements are typically mounted in a cage, sometimes called a separator or retainer. The cage has holes or pockets that contain the rolling elements. The cage is typically guided by an outer ring or inner ring, sometimes called the inner race and outer race.

[0004] It has been found that cages can cause dynamic instability, potentially leading to failure. This instability involves irregular cage movement between the inner and outer rings. Failures occur particularly under harsh operating conditions, such as when lubrication is difficult or impossible during use. This is the case, for example, with bearings used in rocket engines, satellites, and space probe turbopumps. Dynamic instability can also occur more frequently and lead to failure in applications requiring high rotational speeds. In such projects, there have been reported instances where the failure of a relatively small component can have a significant impact on very expensive projects. However, cage failures due to instability have also been reported in more general applications, such as automotive, machining, and aerospace.

[0005] Although the problem of cage instability has been known for some time and has been widely reported and studied in the literature, no satisfactory solution has yet been proposed. Summary of the Invention [Problem to be solved by the invention]

[0006] The object of the present invention is to reduce failures due to cage instability, or at least to provide an alternative to the prior art. [Means for solving the problem]

[0007] This object is achieved by a cage for a rolling element bearing, the cage for a rolling element bearing having an irregular cage radius, the irregular cage radius being an outer cage radius that defines the perimeter of the cage, and / or an inner cage radius defining the inner periphery of the cage; The cage is a first confined region in which the irregular cage radius remains within a confined range between a lower limit and an upper limit; a first protruding region circumferentially adjacent the first confined region, the first protruding region having at least one point where the irregular cage radius extends outside the confined range; a second confined region, the irregular cage radius remaining within a confined range, circumferentially adjacent to the first protruding region; The cage has at least one point where the irregular cage radius extends outside the limited range, and has a second protruding region circumferentially adjacent to the second limited region, and the first limited region circumferentially adjacent to the second protruding region.

[0008] The present invention therefore relates to a cage for a rolling element bearing. The rolling element bearing can be, for example, a roller bearing or a ball bearing. The rolling element bearing can be configured to be used with or without lubrication. Preferably, the rolling element bearing has an outer ring and an inner ring, the inner radius of the outer ring being larger than the outer radius of the inner ring. Thus, when viewed radially, the outer ring is larger than the inner ring. In other words, the rolling element bearing is not a so-called thrust bearing. For example, the rolling element bearing is configured to support radial loads. The bearing can be, for example, a deep groove ball bearing. However, it is also possible for the bearing to be an angular contact bearing.

[0009] The cage may 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 also have multiple pockets for the rolling elements. The pockets may be arranged in a single row or multiple rows, for example, two rows. The pockets may be closed (for example, the cage is a solid cage) or open (for example, the cage is a crown cage). The cage may be made of any suitable material, such as polymers, composite materials such as glass fiber or additional resins, or metals such as steel or brass. The cage may be of any type, such as a stamped cage, a monoblock cage, or a pin-type cage. The cage may be one piece or made of multiple parts, for example, two parts. The cage may be a solid cage. The cage may be a crown cage.

[0010] The cage can be considered to have, for example, 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, it is possible to define the thickness of the cage between the inner and outer cage radii in the radial direction. The width of the cage can optionally be defined in the longitudinal direction. It will be understood that the radius may not be constant across the entire width when viewed in the longitudinal direction, for example, due to the presence of pockets for rolling elements. In the context of the present invention, the pockets can be ignored when determining the inner and outer cage radii.

[0011] At least one of the inner cage radius and the outer cage radius is an irregular cage radius. In this context, irregular means that each cage radius is not constant when viewed from the respective circumferential direction. Although the cage is not perfectly circular (because at least one of the inner and outer radii is not a perfect circle), it is understood that radius in this context refers to the distance between any point on the inner or outer circumference and the center point of the cage. One or both of the inner and outer radii may be an irregular cage radius.

[0012] When viewed circumferentially (i.e., angularly), the cage can be divided into four regions, one of which is a first confined region adjacent to a first protruding region. The first protruding region is adjacent to a second confined region. The second confined region is adjacent to a second protruding region. The second protruding region is finally adjacent to the first confined region. Thus, these four regions cover the entire circumference of the cage, and there are no more regions.

[0013] The bounded range is defined between a lower limit and an upper limit, and the lower limit may be less than or equal to the upper limit. In the first bounded region and the second bounded region, the irregular cage radius remains within the bounded range. However, it should be noted that the irregular cage radius may not be constant while remaining within the bounded range, as long as the lower and upper limits are not exceeded.

[0014] In the first and second protruding regions, the irregular cage radius extends outside the limited range. That is, the irregular cage radius is greater than the upper limit or less than the lower limit. Preferably, the irregular cage radius extends outside the limited range in the same way in both the first and second protruding regions. That is, the irregular cage radius is greater than the upper limit in both the first and second protruding regions or less than the lower limit in both the first and second protruding regions. For example, if the irregular cage radius is the outer cage radius, the irregular cage radius is greater than the upper limit at at least one point in both the first and second protruding regions. For example, if the irregular cage radius is the inner cage radius, the irregular cage radius is less than the lower limit at at least one point in both the first and second protruding regions. The irregular cage radius extends outside the limited range at one or more points (or positions) in the first and second protruding regions. Here, the irregular cage radius may return to the limited range between two points (or positions) that extend outside the limited range.

[0015] The inventors have discovered that providing exactly two protruding regions and two confined regions advantageously reduces cage instability and, consequently, failure. It is theorized that this is because the protruding regions determine where contact between the cage and either the outer or inner ring is possible if instability occurs. Potential contact points between the cage and each ring are thus predefined by well-defined regions. When contact occurs, the protruding regions return the cage to its center, thereby reducing instability. In contrast, using a cage without protruding regions (i.e., a cage with a constant cage radius) allows contact points all around the circumference. This results in unpredictable contact, causing the cage to "bounce around" while contact occurs at different contact points. However, if more than two protruding regions are used, the benefits of the present invention are not achieved. This is believed to be due to the creation of more contact points distributed around the cage circumference, causing the cage to "bounce around" while contact occurs at different, unpredictable contact points.

[0016] In an embodiment, the first confined area covers at least 45 degrees of the circumference, for example at least 60 degrees. In an embodiment, the second confined area covers at least 45 degrees of the circumference, for example at least 60 degrees. The inventors have discovered that unstable movement of the cage can occur even if the first and second confined areas are too small, and consequently the first and second protruding areas are too large.

[0017] In an embodiment, the first confined 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 confined 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 discovered that when the first and second confined areas together cover more than half of the circumference of the cage, the likelihood of contact points between the cage and the respective rings is greatly reduced and any "bouncing" effect is substantially eliminated.

[0018] In an embodiment, the first and second confining regions are larger than the first and second protruding regions. That is, the first confining region is larger than the first protruding region and larger than the second protruding region. The second confining region is also larger than the first protruding region and larger than the second protruding region. The inventors have discovered that this further reduces the possibility of unstable movement of the cage.

[0019] In embodiments, the lower limit of the limited range is smaller than the standard radius by the limited range deviation, and the upper limit of the limited range is larger than the standard radius by the limited range deviation. Thus, the limited range is defined "around" the standard radius. Within the limited region, the irregular cage radius does not extend from the standard radius in either direction (radially inward or radially outward) by more than the limited range deviation. In the protruding region, the irregular cage radius extends further from the standard radius than the limited range deviation.

[0020] Optionally, the standard radius is the average of the irregular cage radii, for example the average is the average of the radii when viewed over the entire circumference, for example the arithmetic mean.

[0021] Optionally, the standard radius is the radius of the cage in a conventional cage design.

[0022] In embodiments, the irregular cage radius is not constant in the first confined region and / or the second confined region when viewed circumferentially. Thus, the irregular cage radius may vary in the first confined region and / or the second confined region while remaining within a confined range, the lower limit of the confined range being smaller than the upper limit. The inventors have discovered that these embodiments advantageously further reduce dynamic instability.

[0023] In an embodiment, the first and second protruding regions are symmetrical, and optionally the first and second limiting regions are symmetrical as well. Symmetry can be advantageous not only for manufacturing but also for limiting rotational instability during use. Furthermore, symmetry at the contact points between the cage and the respective rings further reduces instability. For example, the symmetry can be from a reflection line, where the reflection line passes through the center point of the cage, and the reflection line is, for example, the center line. For example, the symmetry can be from a reflection point, where the reflection point is the center point of the cage. The cage can also be rotationally symmetrical when rotated 180 degrees. It should be noted that in practice, some deviations from symmetry may occur, for example, within manufacturing tolerances.

[0024] In an embodiment, the upper and lower limits of the confined region are between the outer radius of the inner ring and the inner radius of the outer ring.

[0025] For example, if the irregular cage radius is the outer cage radius, the irregular cage radius may exceed the upper limit in the protruding region. In this case, the lower limit can be selected depending on the cage thickness, the outer radius of the inner ring of the rolling element bearing, and the required space between the cage and the inner ring. This is actually very similar to conventional cage designs. The distance between the lower limit and the inner radius of the outer ring can be divided into three zones: the first zone is between the lower limit and the upper limit, the second zone is between the upper limit and the protruding limit, and the third zone is between the protruding limit and the inner radius of the outer ring. The protruding limit is the maximum radius of the irregular cage radius in the first and second protruding regions. The first zone may be defined, for example, as in conventional cage designs, to allow for a cage thickness that ensures sufficient cage strength. The third zone may be defined, for example, as in conventional cage designs, by the required space between the cage and the outer ring to allow for movement. The second zone may be, for example, equal in size to the third zone. In some embodiments, the second and third zones are smaller than the first zone.

[0026] For example, if the irregular cage radius is the inner cage radius, the irregular cage radius may be smaller than the lower limit in the protruding region. In this case, the upper limit can be selected depending on the cage thickness, the inner radius of the outer ring of the rolling element bearing, and the required space between the cage and the outer ring. This is actually very similar to conventional cage designs. The distance between the upper limit and the outer radius of the inner ring can be divided into three zones: a first zone between the upper limit and the lower limit, a second zone between the lower limit and the protruding limit, and a third zone between the protruding limit and the outer radius of the inner ring. In this case, the protruding limit is the minimum radius of the irregular cage radii in the first and second protruding regions. The first zone may be defined, for example, as in conventional cage designs, to allow for a cage thickness that ensures sufficient cage strength. The third zone may be defined, for example, as in conventional cage designs, by the required space to allow movement between the cage and the inner ring. The second zone may be equal in size to the third zone. In some embodiments, the second and third zones are smaller than the first zone.

[0027] In embodiments, the irregular cage radius is configured such that contact between the irregular cage radius and the outer ring or the inner ring is possible only at the first and second protruding regions, respectively, i.e., only at points where the irregular cage radius extends outside a limited range. In particular, the upper and lower limits of the limited range can be arbitrarily defined depending on the protruding limits of the irregular cage radius in the first and second protruding regions and the inner radius of the outer ring or the outer radius of the inner ring.

[0028] For example, if the irregular cage radius is the outer cage radius, the cage can contact the outer ring at the first and second protruding regions but cannot contact the outer ring at the first and second confined regions. If the irregular cage radius is the inner cage radius, the cage can contact the inner ring at the first and second protruding regions but cannot contact the inner ring at the first and second confined regions.

[0029] In embodiments, the first protruding region and / or the second protruding region each consist of a single protrusion extending beyond the limited range. Thus, in the first protruding region and / or the second protruding region, exactly one protrusion extends beyond the limited range. The protrusion may, for example, define the protrusion limit. These embodiments may be relatively simple to manufacture. The protrusion may cover the entire protruding region or may be smaller than the protruding region. The protrusion may have a constant irregular cage radius in part of the protruding region, for example, a cone shape with a plateau. It is also possible for the protrusion to have an irregular cage radius, for example, a cone shape with a rounded tip.

[0030] In embodiments, the first protruding region and / or the second protruding region each include multiple protrusions extending beyond the limited range, e.g., at least two, three, four, or five protrusions. The protrusions extending most outward from the limited range may define the protrusion limit. These embodiments may be advantageous for reducing dynamic instability. The protrusions may have a constant, irregular cage radius in a portion of the protruding region, e.g., a conical shape with a plateau. The protrusions may also have an irregular cage radius, e.g., a conical shape with a (rounded) tip.

[0031] In embodiments, the irregular cage radius is constant in the first confined region and / or the second confined region. Therefore, the irregular cage radius is the same throughout the first confined region and / or the second confined region. There are no protrusions in these regions. Of course, the cage can also include rolling element pockets in these regions. These embodiments may be relatively simple to manufacture. In these embodiments, the upper and lower limits of the confined range may be equal to each other, for example. It will be understood that even if the cage radius is constant, slight variations in the cage radius may occur due to manufacturing tolerances and / or imperfections.

[0032] In an embodiment, the cage comprises a plurality of pockets for rolling elements, for example in a single or double row. Optionally, the irregular radius extends outside a limited range when viewed across the longitudinal width at any point on the cage, excluding the pockets. Optionally, the irregular radius is constant when viewed across the longitudinal width at any point on the cage.

[0033] In an embodiment, the irregular cage radius is a contact cage radius. For example, if the rolling element bearing is an angular contact bearing, only a portion of the outer peripheral surface may be in contact with the outer ring, or only a portion of the inner peripheral surface may be in contact with the inner ring. In such cases, the irregular cage radius refers to that portion of the outer peripheral surface or inner peripheral surface. The radii of other portions of the outer or inner surface do not necessarily need to be defined according to the limited area and protruding area defined herein, as they do not affect the contact between the cage and the ring.

[0034] In embodiments, the cage is monolithic. Thus, the cage is made from a single element. The cage can be, for example, machined, molded, or 3D printed.

[0035] In an embodiment, the cage is made up of two elements attached to each other, e.g., riveted together. For example, the cage can be split into two elements in a longitudinal direction, each element forming half of a pocket. During attachment, the half pocket can be positioned around the rolling elements, and the two elements can be attached to each other to form the pocket around the rolling elements and the cage.

[0036] In an embodiment, the cage comprises an open pocket. For example, the cage can be a crown cage. Crown cages are used in a variety of applications, for example, in electric motors. With the increasing popularity of electric vehicles, there is a need for cages that can withstand high loads while being economically attractive, which can be achieved, for example, by a crown cage embodied in accordance with the present invention.

[0037] In an embodiment, the protrusion is an element disposed on the cage, for example, the protrusion is riveted, glued or screwed.

[0038] In embodiments, the protrusions have any of the following shapes: rounded, rectangular, square, oval, or elliptical.

[0039] In an embodiment, the cage is configured for use in unlubricated or limited lubrication rolling element bearings. Cage failures occur regularly, particularly in applications where lubrication is difficult or impossible, and can be advantageously reduced by using a cage according to the invention. Within the technical field, limiting lubrication refers to a situation in which only a small amount of lubricant is supplied to the bearing. As a result, the balls and rings are not completely separated from each other by a film of lubricant.

[0040] In an embodiment, the irregular cage radius is an outer cage radius, and in the first protruding region and the second protruding region, the irregular cage radius exceeds a limited range beyond an upper limit. Optionally, the cage is configured to be guided by an outer ring of the rolling element bearing. When the cage is guided by the outer ring, contact between the cage and the rolling element bearing occurs between the outer ring. Therefore, the protruding region can be arranged to extend beyond the upper limit, ensuring that contact of the cage occurs with one of the protruding regions.

[0041] In these embodiments, the cage can also be described as follows: a cage for a rolling element bearing, the cage being configured to be guided by an outer ring of the rolling element bearing, the cage having an outer cage radius defining the cage's outer periphery, the cage comprising: a first limited region in which the outer cage radius remains within a limited range between a lower limit and an upper limit, a first protruding region circumferentially adjacent to the first limited region and the cage comprising at least one point where the outer cage radius exceeds the upper limit, a second limited region in which the outer radius of the cage remains within the limited range and the first protruding region, a second protruding region circumferentially adjacent to the second limited region and the cage comprising at least one point where the outer cage radius exceeds the upper limit, the second protruding region circumferentially adjacent to the first limited region, and the first protruding region circumferentially adjacent to the first limited region, and it will be understood that any of the features or embodiments described herein can be applied to this cage.

[0042] For example, if the cage is guided by an outer ring, the dimensions of the cage, inner ring, and outer ring are such that the outer periphery of the cage can only come into contact with the inner periphery of the outer ring, and the inner periphery of the cage cannot come into contact with the outer periphery of the inner ring.

[0043] In an embodiment, the irregular cage radius is an inner cage radius, and in the first protruding region and the second protruding region, the irregular cage radius exceeds the limited range by being smaller than a lower limit. Optionally, the cage is configured to be guided by an inner ring of the rolling element bearing. When the cage is guided by the inner ring, contact between the cage and the rolling element bearing occurs between the inner ring. Therefore, the protruding region can be positioned smaller than the lower limit to ensure that contact of the cage occurs with one of the protruding regions.

[0044] In these embodiments, the cage can also be described as follows: a cage for a rolling element bearing, the cage being configured to be guided by an inner ring of the rolling element bearing, the cage having an inner cage radius defining an inner circumference of the cage, the cage comprising: a first limited region in which the inner cage radius remains within a limited range between a lower limit and an upper limit, a first protruding region circumferentially adjacent to the first limited region, the cage comprising at least one point where the inner cage radius is smaller than the lower limit, a second limited region in which the inner radius of the cage remains within the limited range and is circumferentially adjacent to the first protruding region, and a second protruding region circumferentially adjacent to the second limited region, the cage comprising at least one point where the inner radius is smaller than the lower limit, the second protruding region circumferentially adjacent to the first limited region, it will be understood that any of the features or embodiments described herein can be applied to this cage.

[0045] For example, if the cage is guided by an inner ring, the dimensions of the cage, inner ring, and outer ring are such that the inner periphery of the cage can only come into contact with the outer periphery of the inner ring, and the outer periphery of the cage cannot come into contact with the inner periphery of the outer ring.

[0046] The present invention further relates to a rolling element bearing comprising a cage according to any of the embodiments described herein. Optionally, the rolling element bearing is a roller bearing, such as a cylindrical roller bearing, a spherical roller bearing, or a tapered roller 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 contact ball bearing, a self-aligning ball bearing, a three-point contact ball bearing, or a four-point contact ball bearing. Optionally, the rolling element bearing has an outer ring and an inner ring, and the inner radius of the outer ring is larger than the outer radius of the inner ring. That is, the rolling element bearing is not a so-called thrust bearing or similar bearing.

[0047] The present invention further relates to a satellite, space probe, turbopump (e.g., for rocket engines), turboreactor (e.g., for aircraft), space rocket, or electrified vehicle equipped with rolling element bearings and / or cages according to any of the embodiments described herein. These systems use cages and rolling element bearings under harsh conditions, such as when lubrication is difficult or impossible or in a vacuum environment, which can lead to cage failure. Furthermore, cage failure can have serious consequences in expensive, long-term projects. The present invention advantageously reduces cage failures.

[0048] The present invention further relates to a method, which may relate to a cage and / or rolling element bearing according to the invention, but the cage and / or rolling element bearing or the method are not limited thereto. Features described herein with reference to the cage and / or rolling element bearing have the same meaning in relation to the method, unless expressly defined otherwise. Features described with reference to the cage and / or rolling element bearing can be applied mutatis mutandis to the method to obtain similar advantages.

[0049] The object of the present invention can be achieved, for example, by a method for designing a cage for a rolling element bearing, optionally comprising: a rolling element bearing having an outer ring and an inner ring, the inner radius of the outer ring being greater than the outer radius of the inner ring; optionally the cage being in accordance with any of the preceding claims; and the method comprising: defining an irregular cage radius; and designing the cage; The irregular cage radius is an outer cage radius that defines the perimeter of the cage, and / or an inner cage radius defining the inner periphery of the cage; The cage is a first confined region in which the irregular cage radius remains within a confined range of lower and upper limits, for example covering a circumferential region of at least 90 degrees; a first protruding region circumferentially adjacent the first confined region, the first protruding region having at least one point where the irregular cage radius extends outside the confined range; a second limited region, the second limited region being a region where the irregular cage radius remains within a limited range and circumferentially adjacent to the first protruding region and covering, for example, a circumferential region of at least 90 degrees; The cage has at least one point where the irregular cage radius extends outside the confined range, and a second protruding region circumferentially adjacent to the second confined region and circumferentially adjacent to the first confined region.

[0050] The figures illustrate exemplary embodiments of the present invention. It should be understood that these figures are merely illustrative of one example of how the invention may be practiced, and are not intended to be construed in any way as limiting the scope of the invention and the claims. Like features are designated with like reference numerals throughout the figures. [Brief explanation of the drawings]

[0051] [Figure 1a] FIG. 1a shows a schematic diagram of a rolling element bearing. [Figure 1b] FIG. 1b shows a schematic representation of the cross section AA shown in FIG. 1a. [Figure 1c] FIG. 1c shows a schematic diagram of a rolling element bearing. [Figure 1d] FIG. 1d shows a schematic cross section of the rolling element bearing shown in FIG. 1c. [Figure 2a] Figure 2a shows a schematic side view of a cage according to the invention. [Figure 2b] Figure 2b shows a schematic enlargement of detail A of figure 2a. [Figure 2c] FIG. 2c shows a schematic representation of another view of the cage. [Figure 2d] Figure 2d shows a schematic representation of another view of the cage. [Figure 3a] FIG. 3a shows a schematic diagram of how the cage is designed to be guided by the outer ring. [Figure 3b] Figure 3b shows a schematic diagram of how the cage is designed to be guided by the inner ring. [Figure 4a] Figure 4a shows a schematic example of a cage. [Figure 4b] Figure 4b shows a schematic example of a cage. [Figure 4c] FIG. 4c is a schematic diagram illustrating an example of a cage having irregular, non-constant cage radii in the first and second confined regions. [Figure 4d] FIG. 4d is a schematic diagram illustrating an example of a cage with irregular cage radii that are not constant in the first and second confined regions. [Figure 5a] FIG. 5a is a schematic diagram of a crown cage with protrusions that do not extend across the entire width of the cage. [Figure 5b] FIG. 5b is a schematic diagram of a crown cage with protrusions that do not extend the entire width of the cage. [Figure 5c] FIG. 5c is a schematic diagram of a crown cage with protrusions that do not extend across the entire width of the cage. [Figure 5d] FIG. 5d is a schematic diagram of a crown cage with a protrusion extending across the entire width of the cage. [Figure 6a] Figure 6a shows schematically that the irregular cage radii can be contact cage radii. [Figure 6b] Figure 6b shows schematically that the irregular cage radii can be contact cage radii. [Figure 6c] Figure 6c shows schematically that the irregular cage radii can be contact cage radii. [Figure 6d] Figure 6d shows schematically that the irregular cage radii can be contact cage radii. DETAILED DESCRIPTION OF THE INVENTION

[0052] Figures 1a to 1d show a rolling element bearing 1, Figure 1b shows the cross section AA shown in Figure 1b, and Figure 1d shows the cross section of the rolling element bearing 1 from Figure 1c. Although these figures are shown to explain the rolling element bearing 1 generally and according to the prior art, a person skilled in the art will easily understand from the description herein that the rolling element bearing 1 can be adapted according to the invention by providing a cage according to the invention.

[0053] The rolling element bearing 1 shown in Figures 1a to 1d is a ball bearing with a number of balls 4 as rolling elements. The balls 4 allow the outer ring 2 and the inner ring 3 (sometimes called the outer race 2 and the inner race 3) to move relative to each other. Therefore, 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 with a number of pockets for holding and positioning the balls 4. Figure 1b shows that the cage 5 is guided by the outer ring 2 in this example, but it is also possible for the cage 5 to be guided by the inner ring 3.

[0054] During use, the cage 5 may rotate at high speeds (high rotational speeds). This may cause dynamic instability in the cage 5, ultimately leading to mechanical failure. Failures may occur even more frequently in applications with little or no lubrication. Failure of the cage 5 may render the rolling element bearing 1 completely unusable. This may be particularly problematic if the rolling element bearing 1 cannot be easily replaced, for example, if the rolling element bearing 1 is integrated into a space-based device such as a satellite or space probe. In other applications, such failures may also have significant economic impact, for example, if a rolling element bearing 1 fails in an aircraft.

[0055] 2a-2d show an example of a cage 10 according to the present invention that can be used to reduce dynamic instability and / or failures caused thereby. In this example, the cage 10 is configured to be guided by the outer ring of the rolling element bearing 1. The cage 10 has an inner cage radius 11 that defines an inner circumference 12 and an outer cage radius 13 that defines an outer circumference 14. In this example, the inner cage radius 11 is regular and constant, since it is equal throughout the inner circumference 12. Meanwhile, the outer cage radius 13 is irregular. In this case, the irregularity of the irregular cage radius 13 is embodied as a first protrusion 31 and a second protrusion 32, each of which has a larger outer cage radius 13.

[0056] Detail A from Figure 2a, including first protrusion 31, is shown enlarged in Figure 2b. Also shown in Figure 2b are lower limit 25 and upper limit 26. A limited range can be defined between lower limit 25 and upper limit 26. First protrusion 31 extends beyond upper limit 26 and outside the limited range. Although not explicitly shown in Figure 2a, it is clear that second protrusion 32 also extends beyond upper limit 26. Between first protrusion 31 and second protrusion 32, irregular cage radius 13 remains within the limited range.

[0057] Based on this, cage 10 can be divided into four regions shown in Figure 2a: first confined region 21, first protruding region 22, second confined region 23, and second protruding region 24. In first confined region 21 and second confined region 23, irregular cage radius 13 remains within a confined range between lower limit 25 and upper limit 26. In first protruding region 22 and second protruding region 24, irregular cage radius 13 extends outside the confined range at least once, here at first protruding portion 31 and second protruding portion 32.

[0058] The regions 21, 22, 23, and 24 are adjacent to one another when viewed in the circumferential direction 41 and constitute the entire cage 10. The cage 10 can therefore be precisely divided into these four regions 21, 22, 23, and 24. It has been found that arranging the two protruding regions 22 and 24 between the two limiting regions 21 and 23 improves dynamic stability. If the cage 10 becomes unstable during use and moves out of its desired position, it is usually the first protruding region 31 or the second protruding region 32 that first comes into contact with the outer ring of the rolling element bearing. This predetermined narrow contact surface reduces the cage's instability.

[0059] 2a, it can be seen that, optionally, the first protruding region 22 and the second protruding region 24 are symmetrical to each other, and the first confined region 21 and the second confined region 23 are symmetrical to each other. In this case, it can be seen that the center point 16 of the cage 10 is a reflection point, but multiple reflection lines can also be drawn that pass through the center point 16.

[0060] 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. In particular, when viewed in the circumferential direction 41, the first limited area 21 and the second limited area 23 each cover a circumferential area greater than 90 degrees, in this case, a circumferential area greater than 120 degrees.

[0061] 2c-2d, the cage 10 has multiple pockets 15 for the rolling elements. In this case, the rolling elements are balls and the cage is solid, so the pockets 15 define circular openings, allowing the cage 10 to be used for ball bearings. However, the invention is equally applicable to other types of rolling element bearings, for example, those with cylindrical rolling elements. The invention is also applicable to crown cages. While the cage 10 in the illustrated example has a single row of pockets 15, it is also possible for the cage 10 to have multiple rows of pockets 15.

[0062] As shown in FIG. 2c, the width 17 of the cage 10 can be defined in the longitudinal direction 42. In the illustrated example, the first protrusion 31 and the second protrusion 32 extend across the entire width 17 of the cage 10, with the exception of the recesses 31a for the pockets 15. However, it is also possible for the first protrusion 31 and / or the second protrusion 32 to be provided across only a portion of the width 17, e.g., half of the width 17. This can be determined, for example, by how the outer ring guides the cage 10. For example, the irregular cage radii may be contact cage radii and relate to only a portion of the width 17. This is illustrated further below, for example.

[0063] In the illustrated example, the irregular cage radii, and therefore the heights of the first and second protrusions 31, 32, are constant across the width 17, with the exception of the pockets 15. However, this is not required.

[0064] It should be noted that while in this example the cage inner radius 11 is regular and constant, this is not required. For example, it would be possible for the thickness of the cage 10 (defined between the outer periphery 14 and the inner periphery 12) to be constant, and for the cage inner radius 11 to have the same irregularity as the cage outer radius 13.

[0065] FIG. 3a illustrates a design method for a cage 10 configured to be guided, for example, by the outer ring of a rolling element bearing. In this case, the irregular cage radius may be the outer cage radius. A lower limit 25 and an upper limit 26 are indicated. In the first and second limiting regions 21 and 23, the irregular cage radius remains within the limited range between the lower limit 25 and the upper limit 26. Thus, the irregular cage radius remains within the region indicated by a in FIG. 3a and does not exceed the region indicated by d, for example. However, the limited range in region a still allows the irregular cage radius to remain constant in the first and second limiting regions 21 and 23. In fact, such an implementation may provide additional advantages.

[0066] In the first protruding region 22 and the second protruding region 24, the irregular cage radius exceeds the upper limit 26 and remains so at at least one point within the region designated b. However, the irregular cage radius may be within the limited range designated c at other points in the first protruding region 22 and the second protruding region 24.

[0067] Figure 3a shows an example where the irregular cage radius is the outer cage radius and in the protruding regions 22, 24 the irregular cage radius exceeds the upper limit 26. In this case the lower limit 25 can be selected depending on 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 in fact very similar to conventional cage designs.

[0068] 3a further shows the inner radius 51 of the outer ring of the rolling element bearing, and the protrusion limit 27, which indicates the maximum limit of the irregular cage radii in the first protruding region 22 and the second protruding region 24. The protrusion limit 27 is preferably slightly smaller than the inner radius 51 to allow some space between the cage 10 and the outer ring (when all components are properly centered) to avoid unnecessary friction during rotation. The distance between the protrusion limit 27 and the inner radius 51 can also be selected similarly to conventional cage designs.

[0069] As an example, the distance between lower limit 25 and protrusion limit 27 can be divided into three zones. The first zone (designated as regions a and c) defines a limited range between lower limit 25 and upper limit 26. The second zone is defined between upper limit 26 and protrusion limit 27, with the irregular cage radii extending only into protruding regions 22, 24 (designated region b) and not into limited regions 21, 23 (designated region d). The third zone is defined between protrusion limit 27 and inner radius 51, with the irregular cage radii not extending.

[0070] As an example, the first zone (i.e., the distance between the upper limit 26 and the lower limit 25) can be selected to ensure sufficient strength of the cage 10 at the confined regions 21, 23. This may vary depending on the application, but is generally similar to conventional cage designs. The third zone (i.e., the distance between the protrusion limit 27 and the inner radius 51) can be selected to ensure sufficient space between the cage 10 and the outer ring during use. The second zone (i.e., the distance between the upper limit 26 and the protrusion limit 27) can be selected to be equal to the third zone. While not drawn to scale for clarity, in practice the first zone may be larger than the second and third zones.

[0071] As another example, the upper limit 26 can be selected according to the design of the inner radius 51 and the irregular cage radius in the protruding regions 22, 24. The objective in this example is to ensure that contact between the outer ring and the cage occurs only with the protrusions in the protruding regions 22, 24. It will be understood that various designs are possible, which can be easily implemented by those skilled in the art based on the actual situation.

[0072] As another example, a standard radius may be defined. In that case, the upper and lower limits 26 and 25 may both be selected as a limited range of deviations from the standard radius. Thus, the upper limit 26 is above the standard radius by a limited range of deviations, and the lower limit 25 is below the standard radius by a limited range of deviations. The standard radius may be defined, for example, as the average of the irregular cage radii.

[0073] Figure 3b shows a similar design for a cage 10, for example, designed to be guided by the inner ring of a rolling element bearing. In this case, the irregular cage radius may be the inner cage radius. In the first and second restricted regions 21 and 23, the irregular cage radius remains within a limited range between a lower limit 25 and an upper limit 26, corresponding to the region marked a in Figure 3a, and does not exceed the region marked d, for example. In the first and second protruding regions 22 and 24, the irregular cage radius is smaller than the lower limit 25 at at least one point and extends into the region marked b.

[0074] Figure 3b shows an example where the irregular cage radius is the inner cage radius and in the protruding regions 22, 24 the irregular cage radius is smaller than the lower limit 25. In this case the upper limit 26 can be selected depending on 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 in fact very similar to conventional cage designs.

[0075] Figure 3b further shows the outer radius 52 of the inner ring of the rolling element bearing and the protrusion limit 28, which indicates the minimum limit of the irregular cage radii in the first protrusion region 22 and the second protrusion region 24. The distance between the protrusion limit 28 and the outer radius 52 can also be selected similarly to conventional cage designs to avoid unnecessary friction.

[0076] Also, by way of example, the distance between upper limit 26 and outer radius 52 could be divided into three zones, with lower limit 25 defined as halfway between upper limit 26 and protrusion limit 28. Again, the same reasoning as explained with reference to Figure 3a applies, mutatis mutandis.

[0077] As another example, the lower limit 25 can be selected depending on the design of the outer radius 52 and the irregular cage radii in the protruding regions 22, 24, so that contact between the inner ring and the cage occurs only at the protrusions in the protruding regions 22, 24.

[0078] As another example, a standard radius can be defined. In that case, the upper and lower limits 26 and 25 can both be selected as a limited range of deviations from the standard radius. Thus, the upper limit 26 is above the standard radius by a limited range of deviations, and the lower limit 25 is below the standard radius by a limited range of deviations. The standard radius can be defined, for example, as the average of the irregular cage radii.

[0079] 4a-4d show possible implementations of a cage 10 according to the present invention. These examples relate to a cage 10 with an irregular outer cage radius 13 that extends outside the limited range by exceeding upper limit 26. However, it will be understood that similar embodiments are applicable to cages with an irregular inner cage radius.

[0080] 4a shows an example in which the irregular cage radius 13 is constant in the first confined region 21 and the second confined region 23. In both the first protruding region 22 and the second protruding region 24, the irregular cage radius 13 extends outside the confined region at a single protrusion 61, 62. The first protrusion 61 comprises a first plateau 62, and the second protrusion 63 comprises a second plateau 64, in this case comprising linear extensions 61, 63 from the confined region to the plateaus 62, 64.

[0081] 4b shows an example in which the irregular cage radius 13 is constant in the first confined region 21 and the second confined region 23. In this case, the first protruding region 22 comprises a plurality of protrusions 71, and the second protruding region 24 also comprises a plurality of protrusions 72. In this case, seven protrusions 71, 72 are provided, although other numbers of protrusions 71, 72 are also possible. Between two adjacent protrusions 71 or 72, the irregular cage radius 13 returns to a confined range.

[0082] FIG. 4c shows an example where the irregular cage radius 13 is irregular at the confined regions 21, 23. As shown, the first confined region 21 includes a plurality of bumps 83, and the second confined region 23 also includes a plurality of bumps 84. This has been found to further reduce the dynamic stability of the cage 10. FIG. 4c further shows that the first protruding region 22 includes a single first protrusion 81, and the second protruding region 24 includes a single second protrusion 82. In this example, the first protrusion 81 and the second protrusion 82 have a pointed conical shape rather than a plateau.

[0083] 4d shows an example where the irregular cage radius 13 is elliptical. Thus, the irregular cage radius 13 is irregular in the confined regions 21, 23, and there is only one protrusion 91, 92 in both the first protrusion region 22 and the second protrusion region 24.

[0084] 4a-4d further all show that the first confined region 21 and the second confined region 23 are larger than the first protruding region 22 and the second protruding region 24. The confined regions 21, 23 are larger than 90 degrees and even larger than 120 degrees when viewed in the circumferential direction. It can also be seen that in the example, the protruding regions 22, 24 are symmetrical to each other, and the confined regions 21, 23 are also symmetrical to each other.

[0085] While the previous figures illustrate a solid cage with closed pockets 15, it will be understood that the present invention can also be applied to the crown cage 101 illustrated in Figures 5a, 5b, and 5c. The crown cage 115 has open pockets 115. This is advantageous for positioning the cage 101 on rolling elements such as balls, for example, by snap action. This allows for the manufacture of a relatively inexpensive cage. Such a cage can be used, for example, in electrified vehicles, such as electric vehicles, e.g., vehicles equipped with electric motors, e.g., electric vehicles (EVs) or hybrid vehicles (HEVs or PHEVs). The present invention can enhance the stability of such a cage 101 while keeping costs relatively low. These figures show a first protrusion 131 (part of the first protrusion region) and a second protrusion 132 (part of the second protrusion region) of the cage 101.

[0086] In Figures 5a-5c an embodiment is shown in which the protrusions 131, 132 do not extend across the entire width of the cage 101. In Figure 5d a cage 301 is shown which is again a crown cage 301, but in this case the protrusion 331 extends across the entire width of the cage 301.

[0087] Figures 6a-6d illustrate 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, and Figure 6b shows a cage 205. These figures show the outer ring 202, inner ring 203, cage 205, and rolling elements 204. The bearing 201 is an angular contact ball bearing. The first side 205a of the cage 205 does not contact either ring 202 or 203. The second side 205b of the cage 205 is guided by the outer ring 203. In this case, the irregular cage radius 205b becomes the second side 205b because this portion of the cage 205 defines the contact. The radius of the first side 205a is not critical and does not need to comply with the requirements of the confined area and the protruding area. This is shown, for example, in Figures 6c and 6d, where Figure 6c shows cross section AA of Figure 6b and Figure 6d shows cross section BB of Figure 6b.

[0088] 6c shows the irregular cage radius 205b in the protruding region. The irregular cage radius 205b extends outside the confined area. The radius 205a of the first side 205a also extends outside the confined area and is equal to the irregular cage radius 205b in this area.

[0089] Figure 6d shows irregular cage radius 205b in a limited region. Irregular cage radius 205b remains within the limited range and is clearly smaller than in Figure 6c. However, in Figure 6d, radius 205a of first side 205a still extends outside the limited range and is no longer equal to irregular cage radius 205b in this portion. In other embodiments, radius 205a may differ from radius 205b in various ways.

[0090] Where necessary, specific embodiments of the present invention are described herein; however, it should be understood that the disclosed embodiments are merely examples of the invention, which may be embodied in various ways. Therefore, the specific structural and functional details disclosed herein should not be construed as limiting, but merely as a basis for the claims and as a representative basis for those skilled in the art to implement the invention in various ways in virtually any suitable detailed structure. It is not necessary that all of the described objectives be achieved in a particular embodiment.

[0091] Furthermore, the terms and expressions used herein are not intended to limit the invention, but to facilitate understanding and explanation of the invention. As used herein, the word "a" means one or more than one, unless otherwise specified. The words "multiple," "plurality," or "several" mean two or more than two. The words "comprise," "have," "include," "consist," and "consist of" are broad in meaning and do not exclude the presence of additional elements. Reference numerals in the claims should not be construed as limiting the invention.

[0092] The mere fact that certain technical features are recited in different dependent claims leaves open the possibility that combinations of these technical measures can be used advantageously.

Claims

1. A cage (10) for a rolling element bearing (1), said rolling element bearing having an outer ring (2) and an inner ring (3), said outer ring having an inner radius (51) greater than said inner ring's outer radius (52), said cage having irregular cage radii (11, 13), said irregular cage radii being: an outer cage radius (13) defining the outer periphery (14) of said cage, and / or an inner cage radius (11) defining the inner periphery (12) of the cage; The cage comprises: a first confined region (21) in which the irregular cage radius remains within a confined range between a lower limit (25) and an upper limit (26) and covers a circumferential region of at least 90 degrees; a first protruding region (22) circumferentially adjacent the first confined region, the cage having at least one point where the irregular cage radius extends outside the confined range; a second limited region (23) in which the irregular cage radius remains within the limited range, circumferentially adjacent to the first protruding region and covering a circumferential region of at least 90 degrees; a second protruding region (24) circumferentially adjacent to the second confined region and circumferentially adjacent to the first confined region, the cage having at least one point where the irregular cage radius extends outside the confined range; a cage (10) for a rolling element bearing (1), wherein the lower limit of the limited range is smaller than a reference radius by a deviation of the limited range, and the upper limit of the limited range is larger than the reference radius by a deviation of the limited range, and the reference radius is an average of the irregular cage radii.

2. 2. The cage of claim 1, wherein contact between the irregular cage radius and the outer or inner ring is permitted only at the first and second protruding regions, respectively, and only at points where the irregular cage radius extends outside the limited range.

3. 3. The cage of claim 1 or claim 2, wherein the irregular cage radius is constant in the first confined region and the second confined region.

4. 3. The cage of claim 1 or claim 2, wherein the irregular cage radius is irregular in the first and second confined regions when viewed circumferentially.

5. the first confined area covers a circumferential area of ​​at least 120 degrees, for example at least 150 degrees; 3. A cage according to claim 1 or claim 2, wherein the second confined area covers a circumferential area of ​​at least 120 degrees, for example at least 150 degrees.

6. The cage of any one of claims 1 to 5, wherein the first and second protruding regions are symmetrical, and optionally the first and second confining regions are also symmetrical.

7. The cage of any one of claims 1 to 6, wherein the first and second protruding regions each include a single protruding portion (62, 64, 81, 82, 91, 92) that extends outside the limited range.

8. The cage according to any one of claims 1 to 6, wherein the first and second protruding regions 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 adapted for use in a non-lubricated rolling element bearing or a marginally lubricated rolling element bearing.

10. 10. The cage of claim 1, wherein the irregular cage radius is the outer cage radius, and in the first protruding region and the second protruding region, the irregular cage radius exceeds the upper limit and exceeds outside the limited range.

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

12. 10. The cage of claim 1, wherein the irregular cage radius is the inner cage radius, and in the first protruding and second protruding regions, the irregular cage radius exceeds the limited range by being less than the lower limit.

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

14. 14. A rolling element bearing comprising a cage according to any one of claims 1 to 13, said rolling element bearing comprising an outer ring and an inner ring, the inner radius of said outer ring being greater than the outer radius of said inner ring, and optionally said rolling element bearing comprising: Roller bearings such as cylindrical roller bearings, spherical roller bearings, tapered roller bearings, or A ball bearing such as a single row ball bearing, a double row ball bearing, a deep groove ball bearing, or an angular contact ball bearing, for example, a rolling element bearing in which the irregular cage radius is a contact cage radius and which is a self-aligning ball bearing, a three-point contact ball bearing, or a four-point contact ball bearing.

15. A satellite, a space probe, a turbopump, a space rocket, or an electrified vehicle, comprising a rolling element bearing and / or a cage according to any one of claims 1 to 14.

16. A method for designing a cage for a rolling element bearing, said rolling element bearing having an outer ring and an inner ring, the inner radius of said outer ring being greater than the outer radius of said inner ring, optionally said cage according to any of claims 1 to 13, said method comprising: defining an irregular cage radius; and designing the cage; The irregular cage radius is an outer cage radius defining the periphery of the cage; and / or an inner cage radius defining an inner periphery of the cage; The cage comprises: a first confined area, the irregular cage radius remaining within a confined range between a lower limit and an upper limit, the first confined area covering a circumferential area of ​​at least 90 degrees; a first protruding region circumferentially adjacent the first confined region, the cage having at least one point where the irregular cage radius extends outside the confined range; a first confined region, the irregular cage radius of which remains within the confined range, circumferentially adjacent the first protruding region and covering a circumferential region of at least 90 degrees; the cage has at least one point where the irregular cage radius extends outside the limited range, and a second protruding region circumferentially adjacent to the second limited region and circumferentially adjacent to the first limited region; The method, wherein the lower limit of the limited range is less than a reference radius by a limited range deviation and the upper limit of the limited range is greater than a reference radius by the limited range deviation, and the reference radius is an average of the irregular cage radii.

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