COMPACT SLIDING-CONTACT BEARING WITH A SEALING ARRANGEMENT, AND WATER PUMP WITH SAME

Abstract

A compact bearing is produced by a sliding bearing and has a sealing arrangement for water pumps. The bearing includes a sliding bearing bushing that includes an inner sliding surface and a radial recess having an axial sliding surface, a shaft collar, and a wet-side shaft seal arranged between the wet side and the sliding bearing bushing. A dry-side shaft seal is arranged between the sliding bearing bushing and the dry side. A lubricant reservoir with a substrate, which is porous in at least some sections, is arranged between the wet-side shaft seal and the sliding bearing bushing. The lubricant reservoir includes, in pores of the substrate, a lubricant insoluble in water, and a volume of the lubricant reservoir and a volume of a lubricant filling a total volume of spaces between the wet-side shaft seal and the dry-side shaft seal.

Claims

1. A sliding bearing having a sealing arrangement for water pumps, configured for radial and axial mounting and sealing of a shaft in a housing between a wet side and a dry side, comprising: a sliding bearing bushing made of a sintering material that includes an inner sliding surface for a circumference of the shaft and at least one radial recess having an axial sliding surface to the inner sliding surface; at least one shaft collar providing a radial protrusion to the circumference of the shaft which is formed complementary to the at least one radial recess of the sliding bearing bushing; a shaft seal formed for wet-side sealing and which, in normal use of the sliding bearing, is arranged between the wet side and the sliding bearing bushing; a shaft seal formed for dry-side sealing and which, in the normal use of the sliding bearing, is arranged between the sliding bearing bushing and the dry side; and a lubricant reservoir with a substrate, made of a non-sintered material, which is porous in at least some sections, which is arranged at least between the wet-side shaft seal and the sliding bearing bushing; wherein the lubricant reservoir includes, in pores of the substrate, a lubricant insoluble in water, and a volume of the lubricant reservoir and a volume of a lubricant filling a total volume of spaces between the wet-side shaft seal and the dry-side shaft seal.

2. The sliding bearing having the sealing arrangement according to claim 1, wherein the sliding bearing bushing includes at least one first sintered part and a second sintered part, and the at least one recess is formed at an axial division of the sliding bearing bushing between the first sintered part and the second sintered part.

3. The sliding bearing having the sealing arrangement according to claim 1, wherein: the sliding bearing bushing comprises one single recess between perpendicular staggered sections with axial sliding surfaces, and a single shaft collar is provided by a cylinder ring fixed on the shaft.

4. The sliding bearing having the sealing arrangement according to claim 1, wherein: the volume of the substrate is entirely formed of a structure with open pores, and the open pores are saturated with the lubricant.

5. The sliding bearing having the sealing arrangement according to claim 1, wherein: the substrate is made of a polymer matrix with a defined porosity.

6. The sliding bearing having the sealing arrangement according to claim 1, wherein: the lubricant is an oil.

7. (canceled)

8. The sliding bearing having the sealing arrangement according to claim 1, wherein: in the sliding bearing bushing at least one axial recess is formed that extends through the sliding bearing bushing, and the lubricant reservoir and the lubricant filling a volume of the at least one axial recess.

9. The sliding bearing having the sealing arrangement according to claim 8, wherein: a plurality of axial recesses are formed in an outer circumference of the sliding bearing bushing.

10. The sliding bearing having the sealing arrangement according to claim 8, wherein: the porous substrate of the lubricant reservoir extends through the at least one axial recess and is in contact with the dry-side shaft seal.

11. The sliding bearing having the sealing arrangement according to claim 1, wherein: a sealing lip of the dry-side shaft seal is inclined towards the sliding bearing bushing.

12. The sliding bearing having the sealing arrangement according to claim 1, wherein: the dry-side shaft seal is made of a fluororubber including vinylidene (di)fluoride.

13. The sliding bearing having the sealing arrangement according to claim 1, wherein: the wet-side shaft seal is made of polytetrafluorethylene.

14. (canceled)

15. The sliding bearing having the sealing arrangement according to claim 1, wherein: the sliding bearing bushing, the shaft seals, and the lubricant reservoir are accommodated inside a cylindrical bearing housing.

16. A water pump for a coolant circuit in a vehicle, comprising: a sliding bearing having the sealing arrangement according to claim 1, wherein: the sliding bearing having the sealing arrangement is 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.

17. The water pump according to claim 16, further comprising: a dry-runner electric motor which is connected to the pump shaft.

Description

[0043] The invention will be described hereinafter with the aid of an exemplified embodiment and an example of use in a water pump with reference to the Figures. In the Figures:

[0044] FIG. 1 shows a clearview longitudinal sectional view of one embodiment of an inventive sliding bearing having a sealing arrangement;

[0045] FIG. 2 shows a cross-section of the embodiment of an inventive sliding bearing having a sealing arrangement in a section of a pump housing;

[0046] FIG. 3 shows a longitudinal sectional view of a water pump, in which the embodiment of an inventive sliding bearing having a sealing arrangement is arranged.

[0047] An embodiment of the sealed sliding bearing will be described hereinafter.

[0048] FIG. 1 shows a sliding bearing 1 in the form of an axial and radial integrated sintered sliding bearing. A sliding bearing bushing 11 which is made from a sintering material, in particular a porous sintered metal alloy, provides two inner radial sliding surfaces for the circumference of a shaft 3. The shaft 3 is accommodated rotatably accommodated in the sliding bearing bushing 1 by means of a radial bearing gap of about 3 to 10 μm. The sliding bearing bushing 11a, 11b comprises, in a central axial region, a radial recess 13 having a larger inner diameter than that of the two inner radial sliding surfaces. The sliding bearing bushing 11 provides axial sliding surfaces for a shaft collar 31 at perpendicular transition steps between the inner diameter of the recess 13 and the inner diameter of the inner radial sliding surfaces. The shaft collar 31 is a cylinder ring which is slid and shrunk onto the circumference of the shaft 3 by means of heat treatment and cooling. The shaft collar 31 is rotatably received in the recess 13, wherein two axial bearing gaps are formed between the end-face surfaces of the radial protrusion of the shaft collar 31 and the transition steps of the inner diameters of the sliding bearing bushing 11. The sliding bearing bushing 11 is divided into a first sintered part 11a and a second sintered part 11b. The division extends preferably in the axial centre of the sliding bearing bushing 11 through the recess 13 such that the two sintered parts 11a, 11b can be formed uniformly and can be assembled in a mirrored manner.

[0049] A sliding property between the shaft 3 and the porous sintering material is assisted by means of a lubricant of a lubricant filling of the sliding bearing 1. The sliding bearing bushing 11 and the lubricant filling are received together with a sealing arrangement 2 in a cylindrical bearing shell 6. The cylindrical bearing shell 6 has, on the side illustrated on the right, a stepped base with a through-opening for the shaft 3.

[0050] The sealed sliding 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 sliding bearing 1 even when there is a pressure difference between the two sides 4 and 5. For this purpose, the sliding bearing 1 is equipped with a sealing arrangement 2. The sealing arrangement 2 of the sliding bearing 1 comprises a wet-side shaft seal 24, a dry-side shaft seal 25 and a sealingly effective lubricant reservoir 20.

[0051] The dry-side shaft seal 25 is a radial shaft sealing ring having a dynamic sealing surface with respect to the shaft 3 and closes off an opening gap between the shaft 3 and the through-opening in the stepped base of the bearing shell 6. A sealing lip of the shaft seal 25 is inclined between an offset edge and the shaft circumference inwards into a space which is received in an end side of the sliding bearing bushing 11. The space is taken up by a lubricant filling between the sliding bearing bushing 11 and the shaft seal 25. 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 3 and and a periphery of the bearing shell 6. The shaft seal 24 is held against an end side of the sliding bearing bushing 11 by means of a clamping ring 14. 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 consists of PTFE and the shaft seal 25 consists of FKM.

[0052] As shown in the cross-section in FIG. 2, three grooves are introduced as axial recesses 12 from one end to the other end in an axial direction in the outer peripheral surface of the sliding bearing bushing 11. The axial recesses 12 permit, inter alia, contact over a large surface between the lubricant and the porous sintering material of the sliding bearing bushing 11. Furthermore, the recesses 12 establish a liquid connection between the two shaft seals 24 and 25 outside the bearing gap. In order to provide a circumferential bearing surface for the shaft seals 24 and 25 on the end sides of the sliding bearing bushing 11 also in the region of the axial recesses 12, fixing rings 15 are arranged between the sliding bearing bushing 11 and the shaft seals 25 and 25.

[0053] A lubricant reservoir 20 is located in a space, which is received in an end side of the sliding bearing bushing 11, between the wet-side shaft seal 24 and the sliding bearing bushing 11. In the case of the illustrated embodiment, the lubricant reservoir 20 has three axial extensions consisting of the porous substrate 21 which take up the spaces of the three axial recesses 12 and fill same with the lubricant. Furthermore, the porous substrate 21 extends on the opposite side of the sliding bearing bushing 11 as far as the shaft seal 25 of the dry side and is in contact with a sealing lip thereof.

[0054] In the Figures, the lubricant reservoir 20 is illustrated by horizontal hatching. In a delimiting definition with respect to the remaining volume of the lubricant filling, the lubricant reservoir 20 is composed of a 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 is circumferentially in radial contact with the shaft 3 and an outer boundary surface of the space or the bearing housing 6. The lubricant reservoir 20 has a sponge-like morphology and is surrounded in the regions, not illustrated, without the porous substrate 21 by a lubricant filling which is a liquid cushion consisting of the same lubricant.

[0055] The lubricant reservoir 20 is a hybrid lubricant, 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 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 of the sintering material of the sliding bearing bushing 11 and a loading of the sliding bearing 1.

[0056] 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 sliding bearing 1 until pressure equalisation is established. The rising pressure from a side of the lubricant reservoir 20 illustrated on the left 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 bearing shell 6 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 portion of the sliding bearing 1 located downstream thereof such that any washing out of the lubricant filling 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. Since the sealing lip is lubricated by means of the lubricant, an increased surface pressure in relation to the frictional wear is non-critical.

[0057] An example of use of a water pump 10 in which the sealed sliding bearing 1 is used is described hereinafter.

[0058] As can be seen in the longitudinal sectional view of a water pump 10 in FIG. 3, a pump housing 60 comprises, on a side illustrated on the left, an intake connection 61 and a pressure connection 62 which issue into a pump chamber 40. The intake connection 61 serves as a pump inlet and it is fitted in the form of a housing cover at an open axial end of the pump chamber 40 onto the pump housing 60. The intake connection 61 leads to a pump impeller 41 which is fixed on a pump shaft 30. The circumference of the pump chamber 40 is surrounded by a spiral housing 64. The spiral housing 64 runs tangentially over into the pressure connection 62 which forms a pump outlet. The pump impeller 41 is a known radial pump impeller having a central opening. The flow to be conveyed which flows towards the pump impeller 41 through the intake connection 61 is accelerated by blades of the pump impeller 41 radially outwards into the spiral housing 64 of the pump chamber 40 and is diverted by the pressure connection 62.

[0059] A drive side 50 of the pump housing 60 is located on a side illustrated on the right. The drive side 50 is formed as a receiving chamber of an electric motor 51 in the pump housing 60 and is separated from the pump chamber 40. An axially open end of the drive side 50, formed as a receiving chamber, of the pump housing 60 is closed off by means of a motor cover 65. The electric motor 51 is an inner runner. A rotor 53 is bell-shaped and is connected to the free end of the pump shaft 30 illustrated on the right. The rotor 53 is circumferential to a flange-shaped bearing seat 66 which is configured in a coaxial manner for receiving the sealed sliding bearing 1. The rotor 53 is surrounded by an outer stator 52 which is arranged on the pump housing 60. The electric motor 51 is a dry-runner type, i.e. the field coils of the stator 52 are exposed to an air gap opposite the rotor 53.

[0060] The pump shaft 30 extends between the pump chamber 40 and the drive side 50, formed as a receiving chamber, through the pump housing 60. The flange-shaped bearing seat 66 is arranged between the drive side 50 of the pump housing 60 and the pump chamber 40. The cylindrical bearing housing 6 of the sliding bearing 1 is inserted from the side of the pump chamber 40 to a step portion at the end of the flange-shaped bearing seat 66 and is fixed by means of a press-fit. Therefore, the electric motor 51 is sealed on the dry drive side 50, formed as a receiving chamber, by means of the sealing apparatus 2 of the sliding bearing 1 against the medium to be conveyed in the pump chamber 40.

[0061] In an alternative embodiment, the porous substrate 21 of the lubricant reservoir 20 can be arranged merely between the wet-side shaft seal 24 and the sliding bearing bushing 11, wherein the axial recesses 12 can be omitted or the porous substrate 21 of the lubricant reservoir 20 can terminate at any extension of the axial recesses 12. In these cases, the volume of a remaining space to the dry-side shaft seal 25 is taken up by means of the lubricant filling, i.e. a liquid cushion of the lubricant without the porous substrate 21.

[0062] Alternatively, the shaft collar 31 can have a different contour, such as e.g. one or a plurality of round, wave-like or wedge-shaped radial protrusions or the like, wherein one or a plurality of complementary radial recesses 13 and optionally axial divisions into a plurality of sintered parts are provided accordingly in the sliding bearing bushing 11.

[0063] It is understood that alternatively the number and the shape of the recesses 12 can be varied between the two axial ends of the sliding bearing bushing 11. Likewise, a spiral shape, a labyrinth or other structure of one or a plurality of recesses 12 can be provided. A recess 12 can likewise be provided through a peripheral thickness of the sliding bearing bushing 11.

[0064] The porous substrate 21 can likewise have a core region without open pores or can be fixed in the core region of the lubricant reservoir 20 by means of a different material portion.

LIST OF REFERENCE NUMERALS

[0065] 1sliding bearing [0066] 2 sealing arrangement [0067] 3 shaft [0068] 4 wet side [0069] 5 dry side [0070] 6 bearing housing [0071] 10 water pump [0072] 11 sliding bearing bushing [0073] 11a first sintered part of the sliding bearing bushing [0074] 11b second sintered part of the sliding bearing bushing [0075] 12 axial recess [0076] 13 radial recess [0077] 14 clamping ring [0078] 15 fixing ring [0079] 20 lubricant reservoir [0080] 21 porous substrate [0081] 24 wet-side shaft seal [0082] 25 dry-side shaft seal [0083] 30 pump shaft [0084] 31 shaft collar [0085] 40 pump chamber [0086] 41 pump impeller [0087] 50 drive side [0088] 51 electric motor [0089] 52 stator [0090] 53 rotor [0091] 60 pump housing [0092] 61 intake connection [0093] 62 pressure connection [0094] 64 spiral housing [0095] 65 motor cover [0096] 66 bearing seat