Ball bearing comprising a snap-fit cage

Abstract

The invention relates to a ball bearing (1, 1', 1") comprising: an inner ring (2); an outer ring (3); balls (4) having a diameter (D); a snap-fit cage (5) which guides the balls and has a single cage ring (8); and a flinger disc (10) which extends between the inner ring and the outer ring at a distance from the cage ring so as to form a gap (S). The following relationships are satisfied: (i) 0.65 < S / A < 0.85, (ii) 0.06 < A / D < 0.09, where A is the axial play of the snap-fit cage in the ball bearing.

Description

[0001] ball bearings

[0002] The invention relates to a ball bearing comprising an inner ring, an outer ring, balls with diameter D, and a snap cage guiding the balls with a single cage ring. In particular, the ball bearing is a deep groove ball bearing.

[0003] A ball bearing with a snap cage is described, for example, in WO 2023 / 147799 A1. The snap cage has a cage ring from which radially tapered retaining claws extend axially on one side and offset radially inwards, forming ball pockets designed to receive a single ball each.

[0004] Further snap cages are described, for example, in the documents DE 10 2017 115 881 A1 , DE 10 2020 129 165 A1 , DE 11 2022 000 678 T5 , US 11 ,655,853 B2 , US 11 ,852,195 B2 and US 2023 / 0220875 A1 .

[0005] A ball bearing of this type is known from US 2011 / 0 142 388 A1.

[0006] DE 10 2018 123 495 A1 concerns a friction-reduced ball bearing with a centrifugal disc. It is assumed that the inner bearing ring of the ball bearing rotates, whereas the outer ring is rigidly arranged.

[0007] The invention is based on the objective of providing a ball bearing of the type mentioned above with an increased service life.

[0008] This task is solved by a centrifugal disc that extends between the inner ring and the outer ring at a distance S from the cage ring and the following relationships:

[0009] (i) 0.65 < S / A < 0.85

[0010] (ii) 0.06 < A / D < 0.09 where A is the axial play of the snap cage in the ball bearing.

[0011] Axial play, as is well known, refers to the axial movement of the snap cage mounted between the bearing rings, i.e., its travel between two axial end positions. The axial play is typically 6% to 9% of the ball diameter D.

[0012] The centrifugal disc serves not only as a (non-contacting) bearing seal but also as an overload protection device for the snap cage. It prevents the snap cage from disengaging under overload and simultaneously limits mechanical cage stresses. The defined gap S ensures that, in cases of misuse (i.e., overloading the ball bearing), the snap cage is supported by the centrifugal disc, thus preventing it from disengaging. Furthermore, this support reduces deformation within the snap cage, resulting in lower cage stress and a longer service life. The ball bearing therefore exhibits good emergency running properties and is suitable even for misuse.

[0013] In a preferred embodiment of the invention, the following closer relationship applies: 0.75 < S / A < 0.80 and particularly preferably: S / A ~ 0.78.

[0014] The centrifugal disc can advantageously be attached to the rotating inner ring.

[0015] The advantage over the typical attachment to the stationary outer ring is a smaller differential rotational speed between the centrifugal disc and the snap cage, and consequently less friction between these two friction partners.

[0016] The following relationship shall apply to the width B of the ball bearing: B < 1.3 D [mm] + 2 mm, where the ball diameter has the unit [mm].

[0017] Compared to conventional ball bearings with comparable performance data, the weight of the bearing according to the invention is reduced by approximately 5% in many cases. The same applies to the reduction in bearing width. Despite the comparatively narrow width of the ball bearing, it is characterized by a particularly high power density. In particular, high short-term speeds and even extreme imbalances are tolerable. The economical use of material compared to known designs contributes significantly to a reduced moment of inertia.

[0018] The snap cage can consist primarily of plastic. Furthermore, the cage can contain a fiber content of at least 10% and at most 35% by weight. If the plastic is polyamide, the fiber content must be at least 15% by weight.

[0019] Other plastics suitable for manufacturing the snap-in cage include polyaryletherketone (PAEK), polyetheretherketone (PEEK), and polypropylene (PPS). Combined with fiber reinforcement, these materials allow for the production of lightweight cages that also contribute to low-friction ball bearing operation. The cage material is selected based on factors such as operating temperatures and the media that surround the ball bearing and, depending on the bearing design, may also penetrate its interior.

[0020] The ball bearing can be designed for speed ratings up to 1.3 million n ■ dm or even up to 1.8 million n ■ dm, where n is the bearing speed in revolutions per minute and dm is the pitch circle diameter. The pitch circle diameter is the diameter of the circle that passes through the centers of all the balls.

[0021] The ball bearing according to the invention is suitable, for example, for use in electric motors. When used in electric vehicles, the ball bearing can also be installed at any location outside the electric motor. Application areas characterized by strong vibrations include, for example, compressors, especially scroll compressors, or other machines in which imbalances occur.

[0022] Regarding the design of the ball bearing, basic shapes that have proven successful in a wide variety of applications can be used. For example, the ball bearing can be a deep groove ball bearing. Similarly, the ball bearing can be a thin section bearing. In all cases, the low-friction operation of the ball bearing contributes to reducing GC>2.

[0023] Furthermore, even the economical use of materials means a significant conservation of resources.

[0024] Three exemplary embodiments of the ball bearings according to the invention are explained in more detail below with reference to the drawing. All ball bearings are deep groove ball bearings with a rotating inner ring and a stationary outer ring. Unless otherwise stated, identical or functionally equivalent components or features are designated with the same reference numerals. The figures show:

[0025] Figure 1 shows the first embodiment in sectional view,

[0026] Figure 2 shows the second embodiment in sectional view,

[0027] Figure 3 shows the third embodiment in sectional view, Figure 4 shows the third embodiment in perspective view,

[0028] Figure 5 shows the third embodiment in top view.

[0029] The ball bearing 1 shown in Figure 1 has an inner ring 2 and an outer ring 3 as bearing rings, with balls 4 rolling between them. The balls 4, whose diameter is denoted by D and whose center point is denoted by MK according to Figure 2, are guided in a snap-fit ​​cage 5 made of plastic and roll on a grooved raceway 6 of the inner ring 2 and a grooved raceway 7 of the outer ring 3. The width of the ball bearing 1, denoted by B, is to be measured between the end faces S1 and S2 of the bearing rings. The pitch circle, i.e., the circle with diameter dm passing through the centers MK of all balls 4 (see Figure 2), is a distance B1 from the first end face S1 and a distance B2 from the second end face S2, such that B = B1 + B2. For B1 and B2, the following relationship applies: 1 ,18 < B1 / B2 < 1 ,28, so that the partial circle (offset to the right in the figure) runs off-center between the two end faces S1 and S2.

[0030] The snap-in cage 5 has a single cage ring 8 and arms 9 (see Figure 4) molded onto it, the shape of which is adapted to the diameter D of the balls 4 and which extend essentially in the axial direction of the ball bearing 1 towards the second end face S2. During assembly of the ball bearing 1, the balls 4 snap into the snap-in cage 5 with elastic deformation of the arms 9.

[0031] A centrifugal disc 10, extending between the inner ring 2 and the outer ring 3, is positioned in front of the cage ring 8 as a non-contacting seal. The outer ring 3 has a circumferential groove 11 for inserting the centrifugal disc 10 into it. Grooves 12 are formed in the inner ring 2, whereby the centrifugal disc 10 does not contact the inner ring 2.

[0032] The ball bearing 1' shown in Figure 2 has two centrifugal discs 10, which are also attached to the outer ring 3 on both sides. In this embodiment, the balls 4 and consequently the pitch circle with diameter dm are located centrally between the end faces S1 and S2. The cage ring 8 has a minimum width B11.

[0033] The ball bearing 1" shown in Figure 3 differs from the ball bearing 1' mainly in that the centrifugal disc 10 is mounted in a groove 12 of the inner ring 2 to minimize the comparatively small speed difference and thus friction with the cage ring 8. Consequently, it rotates with the inner ring 2 and is not in contact with the stationary outer ring 3. The centrifugal disc 10 is spaced a distance S from the cage ring 8. The relationships explained at the outset apply to the gap S – as in the previous embodiments of the ball bearings 1 and 1' – to improve the bearing's emergency running properties.

[0034] (i) 0.65 < S / A < 0.85

[0035] (ii) 0.06 < A / D < 0.09 where A is the axial play of the snap cage 5 and is 6% to 9% of the ball diameter D. The gap ratio is ideally S / A ~ 0.78.

[0036] As with the ball bearings 1 and 1' according to Figures 1 and 2 respectively, the ball bearing 1" is narrow, with the following for its width B:

[0037] B < 1.3 D [mm] + 2 mm

[0038] In all embodiments, the snap cage 5 consists primarily of plastic and contains a fiber content of at least 10% and at most 35% by weight. If the plastic is polyamide, the fiber content is at least 15% by weight. Alternative plastics are PAEK, PEEK, or PPS.

Claims

Patent claims 1. Ball bearing (1 , 1 ', 1"), comprising an inner ring (2), an outer ring (3), balls (4) with diameter D and a snap cage (5) guiding the balls (4) with a single cage ring (8), characterized by a centrifugal disc (10) which extends between the inner ring (2) and the outer ring (3) spaced apart by a gap S to the cage ring (8) and the following relations: (i) 0.65 < S / A < 0.85 (ii) 0.06 < A / D < 0.09 where A is the axial play of the snap cage (5) in the ball bearing (1 , 1 ', 1").

2. Ball bearing (1 , 1 ', 1 ”) according to claim 1 , characterized by the relationship: 0.75 < S / A < 0.

80.

3. Ball bearing (1") according to claim 1 or 2, characterized in that the centrifugal disc (10) is attached to the inner ring (2).

4. Ball bearing (1 , 1 ', 1 ”) according to one of claims 1 to 3, characterized in that the following relationship applies to the width B of the ball bearing (1 , 1 ', 1 "): B < 1 ,3- D [mm] + 2 mm.

5. Ball bearing (1 , 1 ', 1 ”) according to one of claims 1 to 4, characterized in that the snap cage (5) comprises plastic as the main component and a fiber content of at least 10 wt.% and at most 35 wt.%.

6. Ball bearing (1 , 1 ',1") according to claim 5, characterized in that the plastic is a polyamide, wherein the fiber content is at least 15 wt.%.

7. Ball bearing (1 , 1 ', 1 ”) according to claim 5, characterized in that the plastic is a PAEK, PEEK or PPS.

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