Bearing unit for an electric coolant pump

Abstract

Electric coolant pump (1) of the wet-running type, comprising a pump housing (2) and an electric motor accommodated therein and surrounded by the coolant, having a stator (3) and a rotor (4), as well as a bearing unit (7) with a pump shaft (8) with a shaft collar (14) and a bearing housing (9) fastened in the pump housing (2) with housing shoulders (18, 19), against which the shaft collar (14) is axially hydrodynamically supported on both sides by means of the coolant, wherein: - the pump shaft (8) is mounted radially in two bores (16, 17) of the bearing housing (9) running on both sides of the shaft collar (14), - the bearing housing (9) comprises a bearing sleeve (10) and two rings (11, 12) forming the bores (16, 17), each of which is secured in the bearing sleeve (10) by means of a press fit, - the bearing unit (7) is axially permeable for the coolant through which the radial and axial plain bearing lubrication takes place, - the housing shoulders (18, 19) each have a plurality of radially extending grooves (22) and the same plurality of axially raised annular segments (23) which alternate circumferentially with the grooves (22), and the axial elevation of the annular segments (23) is oriented according to the direction of rotation of the pump shaft (8).

Description

[0001] The invention relates to an electric coolant pump with a bearing unit comprising a pump shaft with a shaft collar and a bearing housing with a bore in which the pump shaft is radially slide-mounted, and with housing shoulders against which the shaft collar is axially slide-mounted on both sides.

[0002] DE 10 2018 123 909 A1 discloses a bearing unit of the type mentioned above and a dry-running electric coolant pump with the bearing unit. This document also mentions water pumps "in which a radial bearing is designed as a plain bearing that is lubricated by a pumped coolant."

[0003] GB 2 409 008 A discloses a hydrodynamic bearing arrangement of a fluid pump.

[0004] DE 33 07 726 A1 discloses a plain bearing for a pump.

[0005] JP 5 761 560 B2 discloses a hydrodynamic axial plain bearing.

[0006] US 5 951 169 A discloses a pump with a hydrodynamic axial plain bearing.

[0007] DE 1 100 788 A discloses a canned motor for driving pumps.

[0008] The present invention is based on the object of specifying an electric coolant pump of the wet-running type with a bearing unit of the type mentioned above.

[0009] The solution to this problem arises from the features of claim 1. Accordingly, the coolant pump comprises a pump housing and an electric motor accommodated therein and surrounded by the coolant, having a stator and a rotor, as well as a bearing unit with a pump shaft with a shaft collar and a bearing housing fastened in the pump housing with housing shoulders, against which the shaft collar is axially hydrodynamically supported on both sides by means of the coolant, wherein: - the pump shaft is radially supported in exactly two bores of the bearing housing on both sides of the shaft collar, - the bearing housing comprises a bearing sleeve and two rings forming the bores, each of which is secured in the bearing sleeve by means of a press fit, - the bearing unit is axially permeable for the coolant through which the radial and axial plain bearing lubrication takes place, - the housing shoulders each have a plurality of radially extending grooves and the same plurality of axially raised annular segments which alternate circumferentially with the grooves, and the axial elevation of the annular segments is oriented according to the direction of rotation of the pump shaft.

[0010] Advantageous embodiments of the invention are the subject of the dependent claims.

[0011] Further features of the invention will become apparent from the following description and the figures, which illustrate an exemplary embodiment of a bearing unit of an electric coolant pump according to the invention. They show: Fig. 1: the coolant pump with the bearing unit in simplified longitudinal section; Fig. 2: the storage unit in perspective exploded view; Fig. 3: the bearing unit in longitudinal section; Fig. 4: view A according to Fig. 3.

[0012] Fig. Figure 1 shows essential and partially simplified components of a purely electric motor-driven coolant pump 1 of a vehicle cooling system. Shown are a portion of a pump housing 2, an electric motor accommodated therein with a stator 3 and a rotor 4, control electronics 5, an impeller 6, and a bearing unit 7 mounted in the pump housing 2, which transmits the rotational movement of the rotor 4 to the impeller 6. The impeller 6 and the rotor 4 are each mounted on a pump shaft 8 of the bearing unit 7 by means of an interference fit. The impeller can alternatively be mounted by means of a form-fitting connection or a screw connection.

[0013] The coolant pump 1 is a wet-running pump, and the electric motor is accordingly surrounded by the coolant that the coolant pump 1 pumps.

[0014] The Fig. The bearing unit 7 shown in further views in Figures 2 to 4 comprises a bearing housing 9 which supports the pump shaft 8 both radially and axially and has a bearing sleeve 10 which is fastened in the pump housing 2 by means of an interference fit, two rings 11 and 12 which are each fastened in the interior of the bearing sleeve 10 by means of an interference fit, and a further ring 13 which is also fastened in the interior of the bearing sleeve 10 by means of an interference fit.

[0015] The rings 11 and 12 run on both sides of a shaft collar 14 of the pump shaft 8 and have central bores 16 and 17, respectively, relative to the shaft rotation axis 15, which provide radial plain bearings for the pump shaft 8. The shaft collar 14 is formed integrally on the pump shaft 8 by turning. The bearing housing 9 has housing shoulders 18 and 19, which are formed by the axial end faces of one ring 11 on the one hand and the other ring 13 on the other hand, and which provide axial plain bearings for the shaft collar 14. The bearing sleeve 10 has a housing shoulder 20, on which the other ring 13 on the one hand and the other ring 12 on the other hand are axially supported.

[0016] All of the bearings, i.e., both the radial and axial plain bearings of the pump shaft 8, are lubricated by the coolant pumped by the coolant pump 1. For this purpose, the bearing unit 7 is axially permeable to the coolant, which, on the one hand, passes through the continuously hollow cylindrical pump shaft 8 into the pump housing section in which the electric motor is housed, and, on the other hand, through coolant passages 21 into the interior of the bearing unit 7. The essentially circular coolant passages 21 pass through both rings 11 and 12 radially outside their respective bores 16 and 17, respectively.

[0017] The shaft collar 14 is axially hydrodynamically supported on both sides, whereby the hydrodynamically supporting coolant lubricant film is formed by the housing shoulders 18, 19 each having a plurality - in this case seven - of radially extending grooves 22 and the same plurality of axially raised annular segments 23, which alternate circumferentially with the grooves 22. The axial elevation of the annular segments 23 is in accordance with the Fig. 2 oriented in the direction of rotation shown on the pump shaft 8.

[0018] Alternatively, the coolant can be supplied to the interior of the bearing unit only via a coolant passage in the other ring 12.

[0019] The bearing unit 7 explained above consists comparatively of only a few individual parts, namely the pump shaft 8, the two rings 11 and 12, the further ring 13 and the bearing sleeve 10.

[0020] Design alternatives not shown: - The impeller is attached to the pump shaft by means of a positive connection. - The impeller is attached to the pump shaft by means of a screw connection. - The bearing sleeve is overmolded with the plastic of a plastic pump housing. - The pump shaft is made up of several parts, with the shaft collar being a pressed-on ring. - The pump shaft is made up of several parts and comprises a plastic shaft and a steel ring overmolded with plastic as a shaft collar - The pump shaft is an extruded part.

Claims

[1] Electric coolant pump (1) of the wet rotor type, comprising a pump housing (2) and an electric motor accommodated therein and surrounded by the coolant, having a stator (3) and a rotor (4), as well as a bearing unit (7) with a pump shaft (8) with a shaft collar (14) and a bearing housing (9) fastened in the pump housing (2) with housing shoulders (18, 19), against which the shaft collar (14) is axially hydrodynamically supported on both sides by means of the coolant, wherein: - the pump shaft (8) is mounted radially in two bores (16, 17) of the bearing housing (9) running on both sides of the shaft collar (14), - the bearing housing (9) comprises a bearing sleeve (10) and two rings (11, 12) forming the bores (16, 17), each of which is secured in the bearing sleeve (10) by means of a press fit, - the bearing unit (7) is axially permeable for the coolant through which the radial and axial plain bearing lubrication takes place, - the housing shoulders (18, 19) each have a plurality of radially extending grooves (22) and the same plurality of axially raised annular segments (23) which alternate circumferentially with the grooves (22), and the axial elevation of the annular segments (23) is oriented according to the direction of rotation of the pump shaft (8). [2] Coolant pump (1) according to claim 1, characterized by that the rotor (4) is fastened to the pump shaft (8) by means of a press fit. [3] Coolant pump (1) according to claim 1 or 2, characterized by that the bearing sleeve (10) is fastened in the pump housing (2) by means of a press fit. [4] Coolant pump (1) according to one of claims 1 to 3, characterized by that the rings (11, 12) are each penetrated by a coolant passage (21) extending radially outside the bore (16, 17). [5] Coolant pump (1) according to one of claims 1 to 4, characterized bythat one of the housing shoulders (18) is formed by one of the rings (11). [6] Coolant pump (1) according to claim 5, characterized by that the other housing shoulder (19) is formed by a further ring (13) which is fastened in the bearing sleeve (10) by means of a press fit. [7] Coolant pump (1) according to claim 6, characterized by that the bearing sleeve (10) has a housing shoulder (20) against which the further ring (13) on the one hand and the other ring (12) on the other hand are axially supported. [8] Coolant pump (1) according to one of the preceding claims, characterized by that the pump shaft (8) is hollow cylindrical throughout.

Images