ROLLING BEARING HAVING A SEALING ASSEMBLY AND WATER PUMP HAVING SAME

Abstract

A rolling bearing having a sealing arrangement, preferably as a compact bearing and seal for water pumps, is proposed having two axially adjacent rolling-element rows between an outer ring and a shaft bearing section, and a wet-side shaft seal and a dry-side shaft seal. A lubricant reservoir with a substrate that is porous in at least some sections is arranged circumferentially in a radial contact to the shaft section and the outer ring; wherein the lubricant reservoir in pores of the substrate, includes a lubricant insoluble in water, and a volume of the lubricant reservoir and a volume of a lubricant filling with the lubricant take up a total volume of spaces between the wet-side shaft seal and the dry-side shaft seal.

Claims

1-13. (canceled)

14. A rolling bearing for water pumps, wherein the rolling bearing comprises a sealing arrangement and is configured for radial and axial mounting as well as sealing of a shaft of a water pump in a housing between a wet side, which is in contact with a liquid medium which flows through the water pump, and a dry side, which constitutes a drive side, the rolling bearing comprising: an outer ring and a shaft bearing section at which raceways for at least two axially adjacent rolling-element rows are formed; a plurality of rolling elements that are accommodated in at least one rolling-element cage and guided in the rolling-element rows; the sealing arrangement having a wet-side shaft seal arranged between the wet side and a rolling-element row; and a dry-side shaft seal arranged between a rolling-element row and the dry side; and a lubricant reservoir which is arranged circumferentially in a radial contact to the shaft section and the outer ring; wherein the lubricant reservoir comprises a substrate that is porous in at least some sections which, in its pores, includes a lubricant insoluble in water, wherein a volume of the lubricant reservoir and a volume of a lubricant filling which is delimited with respect to the lubricant reservoir and is a liquid cushion filled with the same lubricant, take up a total volume of spaces between the wet-side shaft seal and the dry-side shaft seal, a sealing function of the sealing arrangement is effected by an interaction of the lubricant reservoir with the shaft seals under an externally acting pressure of the liquid medium on the wet side.

15. The rolling bearing having the sealing arrangement according to claim 14, wherein the porous substrate of the lubricant reservoir is arranged between the wet-side shaft seal and a rolling-element row and is in contact with the wet-side shaft seal.

16. The rolling bearing having the sealing arrangement according to claim 14, wherein the porous substrate of the lubricant reservoir is arranged between the wet-side shaft seal and a rolling-element row, as well as between the rolling-element rows, and is in contact with the wet-side shaft seal.

17. The rolling bearing having the sealing arrangement according to claim 14, wherein the porous substrate of the lubricant reservoir is arranged between the wet-side shaft seal and a rolling-element row, between the rolling-element rows, as well as between a rolling-element row and the dry-side shaft seal, and is in contact with both the wet-side shaft seal as well as the dry-side shaft seal.

18. The rolling bearing having the sealing arrangement according to claim 14, wherein the porous substrate of the lubricant reservoir extends through spaces of a rolling-element row and through spaces of the at least one rolling-element cage.

19. The rolling bearing having the sealing arrangement according to claim 14, wherein the volume of the substrate is entirely formed of a structure with open pores, and the open pores are saturated with the lubricant.

20. The rolling bearing having the sealing arrangement according to claim 14, wherein the substrate is made of an elastically flexible polymer matrix with a defined porosity.

21. The rolling bearing having the sealing arrangement according to claim 14, wherein the lubricant is an oil.

22. The rolling bearing having the sealing arrangement according to claim 14, wherein a sealing lip of the dry-side shaft seal is inclined towards a rolling bearing row.

23. The rolling bearing having the sealing arrangement according to claim 14, wherein the dry-side shaft seal is made of a fluororubber including vinylidene (di)fluoride.

24. The rolling bearing having the sealing arrangement according to claim 14, wherein the wet-side shaft seal is made of polytetrafluorethylene.

25. A water pump for a coolant circuit in a vehicle, the water pump having a rolling bearing wherein the rolling bearing comprises a sealing arrangement and is configured for radial and axial mounting as well as sealing of a shaft of a water pump in a housing between a wet side, which is in contact with a liquid medium which flows through the water pump, and a dry side, which constitutes a drive side, the rolling bearing comprising: an outer ring and a shaft bearing section at which raceways for at least two axially adjacent rolling-element rows are formed; a plurality of rolling elements that are accommodated in at least one rolling-element cage and guided in the rolling-element rows; the sealing arrangement having a wet-side shaft seal arranged between the wet side and a rolling-element row; and a dry-side shaft seal arranged between a rolling-element row and the dry side; and a lubricant reservoir which is arranged circumferentially in a radial contact to the shaft section and the outer ring; wherein the lubricant reservoir comprises a substrate that is porous in at least some sections which, in its pores, includes a lubricant insoluble in water, wherein a volume of the lubricant reservoir and a volume of a lubricant filling which is delimited with respect to the lubricant reservoir and is a liquid cushion filled with the same lubricant, take up a total volume of spaces between the wet-side shaft seal and the dry-side shaft seal, a sealing function of the sealing arrangement is effected by an interaction of the lubricant reservoir with the shaft seals under an externally acting pressure of the liquid medium on the wet side; and the rolling bearing having the sealing arrangement being arranged inside a pump housing between a pump chamber in which a pump shaft is connected with a pump impeller and a drive side of the pump housing on which the pump shaft is driven.

26. The water pump according to claim 25, further comprising an electric motor of a dry-runner type which is connected to the pump shaft.

Description

[0036] The invention will be described hereinafter with the aid of an exemplified embodiment with reference to FIG. 1.

[0037] FIG. 1 shows an optional longitudinal sectional view of the rolling bearing having the sealing arrangement according to one embodiment of the invention.

[0038] FIG. 1 shows a rolling bearing 1 in the form of a compact bearing which absorbs both radial forces and also axial forces of a shaft 3 and thus is suitable as a single unit for shaft bearing. A shaft 3 is mounted in the rolling bearing 1 and part of the shaft 3 located within an outer ring 10 of the rolling bearing 1 is referred to as shaft bearing section 31. In an inner peripheral surface of an outer ring 10, two axially adjacent and radially circumferential grooves having a round contour are formed as raceways for spherical rolling elements 11. On a shaft periphery of the shaft bearing section 31, two axially adjacent and radially circumferential grooves having a round contour are similarly formed opposite thereto as raceways for the spherical rolling elements 11. The rolling elements 11 are received in such a manner as to be able to roll in two rolling-element cages 12a, 12b and are held by the rolling-element cages 12a, 12b at equal distances in the circumferential direction of the raceways. The two formations of rolling elements 11 which are guided in the two raceways by means of the rolling-element cages 12, 12b constitute two rolling-element rows 14, 15. By way of the axial distance between the two rolling-element rows 14, 15 and by using the spherical rolling elements 11 in complementary grooves having a round contour, it is ensured that axial and radial forces are applied between the shaft 3 and the outer ring 10.

[0039] The sealed rolling bearing 1 is designed to seal the shaft 3 to be mounted between a wet side 4, which is in contact with a liquid medium, and a dry side 5, such as e.g. a cavity or an outer side, such that the liquid medium does not pass axially through the rolling bearing 1 even when there is a pressure difference between the two sides 4 and 5. For this purpose, the rolling bearing 1 is equipped with a sealing arrangement 2. The sealing arrangement 2 of the rolling bearing 1 comprises a wet-side shaft seal 24, a dry-side shaft seal 25 and a sealingly effective lubricant reservoir 20.

[0040] The wet-side shaft seal 24 is a radial shaft sealing ring having a dynamic sealing surface with respect to the shaft 3 and closes off a radial opening between the shaft bearing section 31 and the outer ring 10. The shaft seal 24 is held in the outer ring 1 in a step-like groove, which is recessed radially outwards, by means of a clamping ring 16. A sealing lip of the shaft seal 24 has a flange on the shaft circumference which faces outwards to the wet side 4. The shaft seal 24 with respect to the wet side 4 consists of PTFE. The dry-side shaft seal 25 is likewise a radial shaft sealing ring having a dynamic sealing surface with respect to the shaft 3 which closes off a radial opening between the shaft bearing section 31 and the outer ring 10. The shaft seal 24 is held in the outer ring 1 in a step-like groove, which is recessed radially outwards, by means of an annular support plate 17 and is acted upon at the inner side of the rolling bearing 1. Accordingly, a sealing lip of the shaft seal 25 is inclined inwards towards the rolling-bearing row 15, more precisely towards a section of the lubricant reservoir 20. A space between a radially outer part of the shaft seal 25 and the section of the lubricant reservoir 20 is taken up by a lubricant filling 22. The shaft seal 25 with respect to the dry side 5 consists of FKM.

[0041] In FIG. 1, the lubricant reservoir 20 is illustrated by checkered hatching. In the illustrated embodiment, the lubricant reservoir 20 takes up spaces between the shaft seals 24, 25 and the rolling-element rows 14, 15 in three sections of the rolling bearing 1. A section of the lubricant reservoir 20 which is the first section to come into contact with a potentially penetrating liquid medium is arranged in a space between the wet-side shaft seal 24 and the closest rolling-element row 14. This section of the lubricant reservoir 20 directed towards the wet side 24 constitutes, in contrast to the two downstream optional sections, an essential section and starting point in relation to the sealing function of the lubricant reservoir 20, as explained hereinafter.

[0042] In a delimiting definition with respect to a remaining volume of a lubricant filling 22, the lubricant reservoir 20 is composed of a volume of the porous substrate 21 as a basic structure for local binding of the lubricant, and of a volume of the lubricant which is bound in the porous substrate 21. The substrate 21 of the lubricant reservoir 20 is circumferentially in radial contact with the shaft 3 and the outer ring 10. In the present embodiment, the porous substrate 21 also extends between the sections of the lubricant reservoir 20 through spaces between the rolling-element rows 14, 15. The lubricant reservoir 20 has a sponge-like morphology. The sections of the lubricant reservoir 20 are in liquid communication with each other and with the lubricant filling 22. The lubricant filling 22 is a liquid cushion of the same lubricant which fills a remaining volume of the lubricant reservoir 20 in the rolling bearing 1 between the shaft seals 24 and 25. Part of the lubricant filling 22 in a space of the shaft seal 25 is illustrated in a cross-hatched manner in FIG. 1.

[0043] The lubricant reservoir 20 is one of the hybrid lubricants mentioned in the introductory part, the principle of which is defined as “solid oil”. The porous substrate 21 consists of an elastic flexible polymer matrix, preferably of a so-called Mikrozella having an open pore structure acting in a capillary manner. The lubricant which is absorbed in the pores of the substrate 21 of the lubricant reservoir 20 or is released in over-saturation and which also forms the lubricant filling 22 is a lubricating oil consisting of synthetic hydrocarbons, a silicone oil, an ester oil or the like, of which the viscosity is adjusted to a porosity of the substrate 21 and a loading of the rolling bearing 1.

[0044] The sealing function of the sealing arrangement 2 occurs when the lubricant reservoir 20 interacts with the shaft seals 24 and 25 under an externally acting pressure of a liquid medium on the wet side 4. As a consequence, a small leakage of the medium occurs under the sealing lip of the shaft seal 24 into the rolling bearing 1 until pressure equalisation is established. The rising pressure from a side of the lubricant reservoir 20 illustrated on the right effects axial compression and radial expansion of the porous substrate 21. Therefore, radial pressing of the sponge-like lubricant reservoir 20 against the shaft 3 and the outer ring 10 is increased. A water-insoluble property of the bound lubricant in the porous substrate 21 ensures media separation between the medium which has penetrated and the section of the rolling bearing 1 located downstream thereof such that any washing out of the lubricant filling 22 is prevented. Moreover, an axial contact pressure on the inwardly inclined sealing lip of the dry-side shaft seal 25 is increased by means of the lubricant filling 22. Since the sealing lip is lubricated by means of the lubricant, an increased surface pressure in relation to the frictional wear is non-critical.

[0045] An example of use, not illustrated, of a water pump in which the sealed rolling bearing 1 is used is described hereinafter.

[0046] In this case, a pump housing on the wet side 4 of the rolling bearing 1, illustrated on the right, comprises a pump chamber in which a pump impeller is driven by the shaft 3. In a typical design of such a water pump, a medium to be conveyed flows towards the pump impeller through an intake connection, is accelerated by blades of the pump impeller radially outwards into a spiral housing of the pump chamber and is diverted by the pressure connection. The wet-side shaft seal 24 is thus arranged downstream of the pump impeller at a passage of the shaft 3 to the pump chamber. Fixing of the rolling bearing 1 in a housing section delimiting the pump chamber downstream of the pump impeller can be provided by means of a press-fit of the outer ring 10 in a bearing seat.

[0047] A drive side of the pump housing is located on the dry side 5 illustrated on the left. The drive side can be formed as a receiving chamber of an electric motor which drives the shaft 3. The dry-side shaft seal 25 is thus arranged at a passage of the shaft 3 to the receiving chamber. Therefore, a compact design of a pump is produced having small axial dimensions, in which the rolling bearing 1 is arranged as a single shaft bearing unit in the housing. The electric motor is reliably sealed with respect to the medium to be conveyed in the pump chamber by the integrated sealing arrangement 2 of the rolling bearing 1

[0048] In embodiments which are not illustrated, the lubricant reservoir 20 can be arranged merely between the wet-side shaft seal 24 and the rolling-bearing row 14, or can extend as far as the next rolling-bearing row 15, whilst a remaining volume is taken up by the lubricant filling 22. The sealing function in accordance with the invention can also be achieved in these, or any other, ratios of volume proportions between the lubricant reservoir 20 and lubricant filling 22.

[0049] In alternative embodiments, not illustrated, the rolling-element rows have other shapes of the rolling elements. According to application-dependent loading or pump type, the two rolling-element rows can correspond to any combination of spherical rolling elements 11 and roller-like, roller-shaped or needle-shaped rolling elements 11 or the like. The rolling-element rows can be guided on a raceway in a combined arrangement in an axially parallel and perpendicular manner, or at an inclined angle to the shaft 3. For example, in the example of use of a displacement pump, in which higher tilting moments occur on the shaft, towards the wet side 4 a rolling-element row 14 having roller-shaped rolling elements can be used which absorbs higher axial forces. Furthermore, more than two rolling-bearing rows 14, 15 can be arranged in the rolling bearing 1 in an axially adjacent manner.

LIST OF REFERENCE NUMERALS

[0050] 1 Rolling bearing [0051] 2 Sealing arrangement [0052] 3 Shaft [0053] 4 Wet side [0054] 5 Dry side [0055] 10 Outer ring [0056] 11 Rolling element [0057] 12a Rolling-element cage [0058] 12b Rolling-element cage [0059] 14 Rolling-element row [0060] 15 Rolling-element row [0061] 16 Clamping ring [0062] 17 Support plate [0063] 20 Lubricant reservoir [0064] 21 Porous substrate [0065] 22 Lubricant filling [0066] 24 Wet-side shaft seal [0067] 25 Dry-side shaft seal [0068] 31 Shaft bearing section