Two hybrid ball bearings and compressor bearing arrangement

Abstract

The invention relates to two hybrid ball bearings and to a compressor bearing arrangement having two hybrid ball bearings for the rotatable support of a rotor of a compressor to a stator of the compressor. The two hybrid ball bearings are arranged face-to-face or back-to-back and are configured to have an optimal axial play according to an inner diameter of an annular inner raceway element of one of the hybrid ball bearings and a pitch diameter of one of the two hybrid ball bearings, and the long bearing service life related to the optimal compressor operation performance is achieved.

Description

Technical Field

[0001] This invention relates to a combination of two ball bearings and a compressor bearing assembly. Background Technology

[0002] For example, in the field of refrigerant compressors, it is known in principle that the refrigerant itself is supplied as an ultra-low viscosity lubricant to the rolling bearings of the compressor, in the sense of lubrication with an ultra-pure lubricating film thickness. This can be pure refrigerant lubrication, except for liquid impurities normally present in the refrigerant. In an improvement (modification) scheme, one or more other substances particularly related to lubrication can be added to the refrigerant, for example, to a total concentration of up to 1%. Furthermore, some of these compressors operate at relatively high speeds. Therefore, the optimization of bearing life is subject to several constraints. Summary of the Invention

[0003] Two hybrid ball bearings have at least one annular inner raceway element on which the balls of at least one of the two hybrid ball bearings roll. The inner raceway element has an inner diameter. If the two hybrid ball bearings are arranged face-to-face or back-to-back, the two hybrid ball bearings are configured to provide axial clearance under zero measurement and zero installation load as follows:

[0004] If the inner diameter is less than or equal to 80 mm, then the axial clearance is between -5 μm and 40 μm.

[0005] If the inner diameter is greater than 80 mm and less than or equal to 180 mm, then the axial clearance is between -5 μm and 50 μm.

[0006] If the inner diameter is greater than 180 mm, the axial clearance is between -5 μm and 70 μm.

[0007] If the two hybrid ball bearings are arranged face-to-face or back-to-back, the two hybrid ball bearings are configured to provide axial clearance under zero measurement and zero installation load as follows:

[0008] If the pitch circle diameter of one of the two hybrid ball bearings is less than or equal to 100 mm, then the axial clearance is between -5 μm and 40 μm.

[0009] If the pitch circle diameter of one of the two hybrid ball bearings is greater than 100 mm and less than or equal to 200 mm, then the axial clearance is between -5 μm and 50 μm.

[0010] If the pitch circle diameter of one of the two hybrid ball bearings is greater than 200 mm, then the axial clearance is between -5 μm and 70 μm.

[0011] A compressor bearing assembly comprising two hybrid ball bearings for rotatable support of the compressor rotor against the compressor stator, wherein the two hybrid ball bearings are arranged face-to-face or back-to-back and have the following axial clearance under zero measurement and zero installation load:

[0012] If the inner diameter of the annular inner raceway element of at least one of the two hybrid ball bearings is less than or equal to 80 mm, or if the pitch circle diameter of one of the two hybrid ball bearings is less than or equal to 100 mm, then the axial clearance is between -5 μm and 40 μm.

[0013] If the inner diameter of the annular inner raceway element of at least one of the two hybrid ball bearings is greater than 80 mm and less than or equal to 180 mm, or if the pitch circle diameter of one of the two hybrid ball bearings is greater than 100 mm and less than or equal to 200 mm, then the axial clearance is between -5 μm and 50 μm.

[0014] If the inner diameter of the annular inner raceway element of at least one of the two hybrid ball bearings is greater than 180 mm, or if the pitch circle diameter of one of the two hybrid ball bearings is greater than 200 mm, then the axial clearance is between -5 μm and 70 μm.

[0015] Extensive investigations were conducted. These investigations were performed on two hybrid ball bearings in X- and O-arrangements for high-speed (between 2500 and 25000 rpm or ndm values ​​between 500,000 and 1,200,000 mm / 60 s) refrigerant compressor applications. The bearings, particularly the hybrid angular contact ball bearings, utilized ultra-low viscosity lubricants (forming an ultra-thin lubricating film thickness of less than 200 nm), especially modern environmentally friendly refrigerants, or refrigerants having a total concentration of one or more other particularly lubricating substances reaching a maximum of 1%. Bearing assemblies of various dimensions and internal and external tolerances were thus investigated. The focus of these investigations was on optimized bearing life in relation to improved compressor operating performance. The key findings of these extensive investigations are that long bearing life and good compressor performance (together) are strongly influenced by the proper selection of the axial clearance of the two hybrid ball bearings. The optimal axial clearance depends on the bearing dimensions, particularly the inner diameter of the annular inner raceway element (or short inner ring), and the pitch circle diameter of the balls, for example, in devices where a traditional inner bearing ring is absent (e.g., if the inner raceway is directly formed on the rotating shaft). Specifically, insufficient axial clearance leads to high inner bearing load conditions, high contact stress, and lubricant film breaks, resulting in short bearing life. Conversely, excessive axial clearance causes sliding motion between the balls and raceways, resulting in low contact stress, increased viscosity, and reduced lubricant film thickness, leading to further wear and short bearing life. Bearing stiffness and rotor positioning accuracy are also negatively affected by excessive clearance. Therefore, the design rules described above ensure long bearing life, which is associated with good compressor performance.

[0016] Further advantages, features, and details of the present invention arise from (or are obtained from) the exemplary embodiments of the invention described below with reference to the accompanying drawings. Attached Figure Description

[0017] Figure 1a and Figure 1b The longitudinal section of the upper half of two hybrid ball bearings is shown. Figure 1a They were arranged to face each other, in Figure 1b The two sides were arranged back to back.

[0018] Figure 2 A longitudinal section of the upper region of the bearing assembly of the refrigerant compressor is shown, and

[0019] Figure 3 It was shown (or passed through). Figure 2 The cross-section at the center of the device. Detailed Implementation

[0020] As an embodiment of the present invention Figure 1a and Figure 1b A longitudinal section is shown (through) the upper half of the two hybrid ball bearings. Thus... Figure 1a A bearing assembly (or arrangement) of two hybrid angular contact ball bearings is shown, wherein the two bearings are arranged relative to each other in a face-to-face arrangement (also referred to as an X arrangement). Figure 1b The diagram shows a bearing arrangement of two hybrid angular contact ball bearings, wherein the two bearings are arranged back-to-back (also known as an O arrangement) relative to each other. Figure 1a and Figure 1b Each of the two mixed angular contact ball bearings comprises annular outer raceway elements 12 and 22 and inner raceway elements 11 and 21. The inner and outer raceway elements 11, 21, 12, and 22 are made of stainless steel, particularly high-nitrogen stainless steels such as Chromex 40, Cronidus 30; X30CrNoN15-1, X40CrMoVN16-2, NitroMax, or similar materials having a hardness greater than HRC 58 at least at the raceway and a pitting potential greater than or equal to (according to ASTM G61-86) -225 mV for corrosion resistance. The inner raceway elements 11 and 21 have inner (straight) diameters d and d', respectively.

[0021] A series of ceramic balls 15 and 25 (e.g., Si3N4) are arranged for each ball bearing, located between the inner raceway element and the outer raceway elements 11, 21, 12, and 22 of the corresponding ball bearing. Balls 15 and 25 are snapped and held in cages 14 and 24. In this configuration, cages 14 and 24 prevent balls 15 and 25 within the corresponding rows of balls 15 and 25 from contacting each other. Cages 14 and 24 are made of fiber-reinforced PEEK. Thus, the rows of balls 15 define a pitch diameter dm, which is the diameter of the circle passing through the center point of all balls 15; the rows of balls 25 define a pitch diameter dm' in a similar manner.

[0022] Each of the mixed angular contact ball bearings is shown with contact angles α and β. These contact angles α and β are angles between (on the one hand) the line connecting the balls 15 or 25 with the nominal contact points of the outer raceway elements 12 and 11 and the inner raceway elements 22 and 21, and (on the other hand) the plane of the ball bearing perpendicular to the axial direction.

[0023] exist Figure 1a and Figure 1bIn this embodiment, the two mixed angular contact ball bearings are identical, specifically meaning that their inner diameters d and d', pitch circle diameters dm and dm', and contact angles α and β are the same. In other embodiments, the contact angles α and β are different from each other, for example, to accommodate different expected axial loads in one axial direction and another. Of course, there are special cases where the inner diameters d and d' and / or pitch circle diameters dm and dm' of the two mixed ball bearings are also different from each other.

[0024] Two hybrid ball bearings are constructed and manufactured for high speeds between 2500 and 25000 rpm or for ndm values ​​between 500,000 and 1,200,000 mm / 60 s, where the ndm value is the result of multiplying the speed by the pitch circle diameter dm or dm'. Furthermore, the two hybrid ball bearings are constructed and manufactured such that they exhibit a specific axial clearance C (at zero measurement and zero installation load) when not in use (like new and unused), as described above in this invention, to ensure optimized bearing life and optimized compressor operating performance (both achieved together).

[0025] More specifically, the two hybrid angular contact ball bearings have an inner diameter d = d' = 150 mm, a pitch circle diameter dm = dm' = 187.5 mm, a contact angle α = β = 15°, and an axial clearance C of approximately 40 μm under zero measuring and zero installation load conditions. In another embodiment, different from the one mentioned above, the contact angles α and β of the two hybrid ball bearings are different, for example, α = 15°, β = 30°, and then C is approximately 38 μm.

[0026] Therefore, the negative axial clearance C must be determined by reference. Figure 1a and Figure 1b The understanding is as follows: For Figure 1a With the raceways arranged face-to-face, a negative axial clearance C means that the axial clearance is no longer between the two inner raceway elements 11 and 21 (which then contact each other), but between the two outer raceway elements 12 and 22 (the absolute value of the negative axial clearance C is shown). For Figure 1b The back-to-back arrangement means that the negative axial clearance C is no longer between the two outer raceway elements 12 and 22 (which then contact each other), but between the two inner raceway elements 11 and 21 (showing the absolute value of the negative axial clearance C).

[0027] Thus, two mixed angular contact ball bearings can be paired bearings, which increases the degree of freedom to ensure the desired axial clearance C; or they can be unpaired, which increases the tolerance requirements for the individual bearings to ensure the desired axial clearance C, but of course, this is easier from an operational and installation point of view because there is no need to follow a pairing relationship.

[0028] Of course, in other embodiments, depending on the required load-carrying capacity at the corresponding mounting position of the bearing and the application requirements, it is possible to... Figure 1a and Figure 1b The left and / or right side of the bearing, or possibly also on the left and / or right side of the bearing. Figure 1a and Figure 1b Between the two bearings, there are one or more additional mixed ball and / or roller (especially cylindrical roller) bearings. Therefore, these additional bearings do not affect... Figure 1a and Figure 1b The axial clearance between the two bearings in the bearing.

[0029] As an exemplary embodiment of the present invention Figure 2 The diagram shows a longitudinal section passing through the upper region of the bearing assembly of a refrigerant compressor, particularly a large centrifugal air conditioning compressor with direct drive. Figure 3 It shows crossing Figure 2 The diagram shows a cross-section at the center. The compressor includes a housing 110, in... Figure 2 and Figure 3 The image shows only the area of ​​the housing that is connected to / related to the bearing assembly. Additionally, the housing 110 includes an axial circular cylindrical bore 118 that accommodates the hybrid ball bearing and the outer intermediate ring 130.

[0030] In hole 118, according to Figure 1b The two mixed angular contact ball bearings are spaced apart from each other by an outer intermediate ring 130. The annular outer raceway elements 12 and 22 are fixed in the housing 110 in a manner known per se (but not shown in detail). Similarly, the inner raceway elements 11 and 21 are fixed in a known manner (but not shown) to the shaft of the compressor, which is also not shown, and the compressor shaft is configured to rotate relative to the housing 110. In this case, the shaft may, for example, be merged into the rotor of a motor used to drive the shaft. For example, in... Figure 2 On the right side of the diagram, the impeller of the compressor for the refrigerant in the air conditioning system can be arranged on a shaft. In any case, the shaft can have... Figure 2The bearing position shown is at a distance (or spaced apart) from another bearing position, for example, on the other axial side of the drive (or actuator). This other bearing position can be... Figure 2 and Figure 3 The designs shown can be the same, similar, or different.

[0031] A series of ceramic balls 15 and 25 are arranged between the outer raceway elements and the inner raceway elements 12, 22, 11, and 21 of the corresponding ball bearings. Balls 15 and 25 are respectively snapped into and held in cages 14 and 24. Cages 14 and 24 prevent the balls 15 and 25 in the corresponding rows from contacting each other.

[0032] An outer intermediate ring 130 is arranged between the two outer raceway elements 12 and 22 of two mixed angular contact ball bearings, and an inner intermediate ring 138 is arranged between the inner rolling surface elements 11 and 12 of the two ball bearings. The housing 110 includes a radial cylindrical bore 112 through which a refrigerant nozzle 140 can be screwed. The outer intermediate ring 130 is formed with a slot 132 aligned with the radial bore 112 and a radial cylindrical penetration 134 opposite to the slot 132. The radial penetration 134 corresponds in position to the radial bore 114 provided in the housing 110, which serves as a drain for refrigerant supplied to the bearing assembly.

[0033] The bearing assembly is configured to be lubricated using more or less pure oil-free refrigerant (such as one of the modern environmentally friendly refrigerants), or using a refrigerant containing one or more other particularly lubricating substances at a total concentration of up to 1%, as described below: a nozzle 140, passing through a slot 132 of the bore 110 and the intermediate ring 130, is screwed into a bore 112 of the housing 110 and secured, for example, by means of an adjusting nut 148. For this purpose, the nozzle 140 is designed to have external threads at least in its upper region, and the bore 112 is designed to have corresponding internal threads at least in its upper region. Furthermore, the nozzle 140 includes a channel 144, which merges into a Y-shaped outlet channel 144 on the bearing side. Thus, the Y-shaped design of the channel 144 is particularly advantageous if, for example, sufficient space is not available for a T-shaped design.

[0034] When the corresponding refrigerant line is connected to the upper end of nozzle 140, refrigerant supply is then realized (or executed) via channel 142. The refrigerant is then delivered via Y-shaped outlet channel 144 (between the lower edges of cages 14 and 24 and the mantles of inner raceway elements 11 and 21), and thereby injected directly into the rolling region of the mixed angular contact ball bearing. For this purpose, the ball bearing and nozzle 140 are constructed in a structurally and geometrically coordinated manner relative to each other, such as the screw-in depth within bore 112.

[0035] During compressor operation, the refrigerant is supplied in a saturated liquid state. The bearing assembly is configured to maintain the refrigerant pressure state, which largely prevents the refrigerant from passing over into the gaseous state. In particular, the diameter of the Y-shaped outlet channel is sized accordingly. Furthermore, the geometry of the bearing (especially regarding the axial free passage capability of the injected refrigerant) and the geometry of the discharge section 114 are designed accordingly, particularly in a restrictive manner. Thus, the diameter of the channel is designed such that the pressure drop upstream of the Y-shaped outlet channel 144 is very small. The refrigerant passes through the outlet channel 144 in liquid form. After leaving the outlet channel 144, some of the refrigerant converts into a gas due to the pressure drop across the outlet channel 144, bearing friction, and the time spent flowing through.

[0036] In other embodiments, the outer intermediate ring 130 can also be rotated 180° to align the through-hole 134 with the hole 112 and the slot 132 with the hole 114. Another embodiment involves the slot 132 and the through-hole 134 not being opposite each other, but being arranged, for example, staggered 160° or 140° circumferentially. In yet another embodiment, the slot 132 can be replaced by another radial through-hole. Furthermore, the outer intermediate ring can include multiple through-holes for more than one nozzle and possibly for additional outflow sections. Alternatively, the associated through-holes or slots of the discharge section 114 and the outer intermediate ring can be omitted.

[0037] In other embodiments, the inner intermediate ring 138 may support the introduction of refrigerant into the rolling-off zones, particularly through a radially outward bulging construction of its housing, such as a roof. In still other embodiments, the nozzle may, of course, be secured to the housing in other ways.

[0038] In other embodiments, the lubrication spacer can be constructed according to DE 20 2017 106 076 U1 and CN 205 025 807U.

[0039] Of course, it must be emphasized that intermediate rings 130 and 138 do not affect the desired axial clearance C (in the case of zero measurement and zero installation load of the bearing). In other embodiments, it can also be a single-piece (or integral) intermediate ring, or there can be multiple such intermediate rings for each additional bearing. In other embodiments, it can also be, for example, a single washer located between the inner raceway elements 11 and 21 or the outer raceway elements 12 and 22, particularly in relation to different supplies of lubricating refrigerant, for example, axially (or in the axial direction) separated from at least one of the sides. Thus, such a washer can also be included in the device to control the desired axial clearance C, and thus, in principle, such intermediate rings can also be used and constructed for this purpose.

Claims

1. Two hybrid ball bearings, comprising: At least one annular inner raceway element having an inner diameter, on which the balls of at least one of the two hybrid ball bearings roll. If the two hybrid ball bearings are arranged face-to-face or back-to-back, the two hybrid ball bearings are configured to provide axial clearance under zero measurement and zero installation load as follows: If the inner diameter is less than or equal to 80 mm, then the axial clearance is between -5 μm and 40 μm. If the inner diameter is greater than 80 mm and less than or equal to 180 mm, then the axial clearance is between -5 μm and 50 μm. If the inner diameter is greater than 180 mm, the axial clearance is between -5 μm and 70 μm.

2. The two hybrid ball bearings according to claim 1, characterized in that, The two hybrid ball bearings are in an unused state, and the two hybrid ball bearings are identical.

3. The two hybrid ball bearings according to claim 1, characterized in that, The raceway elements of the two hybrid ball bearings are made of steel, the balls are made of ceramic material, and the cages for the balls are made of plastic.

4. The two hybrid ball bearings according to claim 3, characterized in that, The steel is a stainless high-nitrogen steel used in rolling bearings.

5. The two hybrid ball bearings according to claim 3, characterized in that, The plastic is glass fiber reinforced plastic.

6. The two hybrid ball bearings according to claim 3, characterized in that, The plastic is a glass fiber reinforced plastic including PEEK.

7. The two hybrid ball bearings according to claim 1, characterized in that, The first of the two hybrid ball bearings includes an annular first outer raceway element and a first inner raceway element, and the second of the two hybrid ball bearings includes an annular second outer raceway element and a second inner raceway element, with at least one hollow cylindrical distance element disposed and positioned between the two outer raceway elements and / or the two inner raceway elements.

8. The two hybrid ball bearings according to claim 7, characterized in that, The at least one hollow cylindrical distance element is a lubrication spacer or a distance ring.

9. The two hybrid ball bearings according to claim 1, characterized in that, The two hybrid ball bearings are hybrid angular contact ball bearings with a contact angle between 10° and 40°.

10. The two hybrid ball bearings according to claim 9, characterized in that, The contact angle is between 15° and 30°.

11. The two hybrid ball bearings according to claim 9 or 10, characterized in that, The contact angles of the two hybrid ball bearings are different.

12. The two hybrid ball bearings according to claim 11, characterized in that, The contact angle of the first of the two hybrid ball bearings is between 10° and 20°, and the contact angle of the second of the two hybrid ball bearings is between 21° and 35°.

13. The two hybrid ball bearings according to claim 1, characterized in that, At least one of the two hybrid ball bearings is configured for high speeds between 2500 rpm and 25000 rpm or between 500000 and 1200000 mm / 60s. m Value, wherein nd m The value is the result of multiplying the rotational speed by the pitch circle diameter.

14. The two hybrid ball bearings according to claim 1, characterized in that, The two hybrid ball bearings are paired to form a synchronization group.

15. The two hybrid ball bearings according to claim 1, characterized in that, The two hybrid ball bearings are in new conditions, and the two hybrid ball bearings are identical.

16. The two hybrid ball bearings according to claim 1, characterized in that, The two hybrid ball bearings are identical and are not in operation.

17. Two hybrid ball bearings, wherein if the two hybrid ball bearings are arranged face-to-face or back-to-back, the two hybrid ball bearings are configured to provide the following axial clearance under zero measurement and zero installation load: If the pitch circle diameter of one of the two hybrid ball bearings is less than or equal to 100 mm, then the axial clearance is between -5 μm and 40 μm. If the pitch circle diameter of one of the two hybrid ball bearings is greater than 100 mm and less than or equal to 200 mm, then the axial clearance is between -5 μm and 50 μm. If the pitch circle diameter of one of the two hybrid ball bearings is greater than 200 mm, then the axial clearance is between -5 μm and 70 μm.

18. The two hybrid ball bearings according to claim 17, characterized in that, The two hybrid ball bearings are in an unused state, and the two hybrid ball bearings are identical.

19. The two hybrid ball bearings according to claim 17, characterized in that, The two hybrid ball bearings are hybrid angular contact ball bearings with a contact angle between 10° and 40°.

20. The two hybrid ball bearings according to claim 19, characterized in that, The contact angle is between 15° and 30°.

21. The two hybrid ball bearings according to claim 19 or 20, characterized in that, The contact angles of the two hybrid ball bearings are different.

22. The two hybrid ball bearings according to claim 21, characterized in that, The contact angle of the first of the two hybrid ball bearings is between 10° and 20°, and the contact angle of the second of the two hybrid ball bearings is between 21° and 35°.

23. The two hybrid ball bearings according to claim 17, characterized in that, At least one of the two hybrid ball bearings is configured for high speeds between 2500 rpm and 25000 rpm or between 500000 and 1200000 mm / 60s. m Value, wherein nd m The value is the result of multiplying the rotational speed by the pitch circle diameter.

24. The two hybrid ball bearings according to claim 17, characterized in that, The two hybrid ball bearings are paired to form a synchronization group.

25. The two hybrid ball bearings according to claim 17, characterized in that, The two hybrid ball bearings are in a new condition, and the two hybrid ball bearings are identical.

26. The two hybrid ball bearings according to claim 17, characterized in that, The two hybrid ball bearings are identical and are not in operation.

27. A compressor bearing assembly, comprising: Two hybrid ball bearings are used for the rotatable support of the compressor rotor against the compressor stator, wherein... The two hybrid ball bearings are arranged face-to-face or back-to-back, with the following axial clearance under zero measurement and zero installation load. If the inner diameter of the annular inner raceway element of at least one of the two hybrid ball bearings is less than or equal to 80 mm, or if the pitch circle diameter of one of the two hybrid ball bearings is less than or equal to 100 mm, then the axial clearance is between -5 μm and 40 μm. If the inner diameter of the annular inner raceway element of at least one of the two hybrid ball bearings is greater than 80 mm and less than or equal to 180 mm, or if the pitch circle diameter of one of the two hybrid ball bearings is greater than 100 mm and less than or equal to 200 mm, then the axial clearance is between -5 μm and 50 μm. If the inner diameter of the annular inner raceway element of at least one of the two hybrid ball bearings is greater than 180 mm, or if the pitch circle diameter of one of the two hybrid ball bearings is greater than 200 mm, then the axial clearance is between -5 μm and 70 μm.

28. The compressor bearing assembly according to claim 27, characterized in that, The first of the two hybrid ball bearings includes an annular first outer raceway element and a first inner raceway element, and the second of the two hybrid ball bearings includes an annular second outer raceway element and a second inner raceway element, with at least one hollow cylindrical distance element disposed and positioned between the two outer raceway elements and / or the two inner raceway elements.

29. The compressor bearing assembly according to claim 28, characterized in that, The at least one hollow cylindrical distance element is a lubrication spacer or a distance ring.

30. The compressor bearing assembly according to claim 27, characterized in that, The two hybrid ball bearings are hybrid angular contact ball bearings with a contact angle between 10° and 40°.

31. The compressor bearing assembly according to claim 30, characterized in that, The contact angle is between 15° and 30°.

32. The compressor bearing assembly according to claim 30 or 31, characterized in that, The contact angles of the two hybrid ball bearings are different.

33. The compressor bearing assembly according to claim 32, characterized in that, The contact angle of the first of the two hybrid ball bearings is between 10° and 20°, and the contact angle of the second of the two hybrid ball bearings is between 21° and 35°.

34. The compressor bearing assembly according to claim 27, characterized in that, At least one of the two hybrid ball bearings is configured for high speeds between 2500 rpm and 25000 rpm or between 500000 and 1200000 mm / 60s. m Value, wherein nd m The value is the result of multiplying the rotational speed by the pitch circle diameter.

35. The compressor bearing assembly according to claim 27, characterized in that, At least one of the two hybrid ball bearings is lubricated with an ultra-low viscosity lubricant.

36. The compressor bearing assembly according to claim 35, characterized in that, The ultra-low viscosity lubricant is a pure refrigerant or a refrigerant having at least one other lubrication-related substance in an amount of up to a maximum of 1%.

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