Bearing arrangement for a pump motor

Abstract

Bearing arrangement (1) for a pump motor comprising a pump housing (2), a pump head (3) and at least one pump rotor (4), a motor housing arrangement (5) with a stator (6) and a rotor (7) arranged around a motor shaft (8), and a bearing plate (9) arranged between the motor housing arrangement (5) and the pump housing (2), a fixed bearing (10) on the side of the motor housing arrangement (5) in the bearing plate (9) and a second bearing (11) in the pump head (3) for supporting the motor shaft (8), wherein the second bearing (11) comprises a first and a second bearing element (12, 13), and the second bearing element (13) is pressed into the first bearing element (12), wherein the second bearing (11) has a first bearing surface (18) and a second bearing surface (19), wherein an outer surface (20) of the first bearing surface (18) bears against the at least one pump rotor (4),wherein an inner surface (21) of the second bearing surface (19) bears against the motor shaft (8) and wherein the first and second bearing elements (12, 13) have different materials from one another.

Description

[0001] The invention relates to a bearing arrangement for a pump motor according to the preamble of claim 1.

[0002] Pumps for conveying fluids have been used in the automotive sector for some time, particularly as water or oil pumps for a wide variety of applications in motor vehicles. For example, positive displacement pumps such as gerotor pumps can be used, in which a pump rotor device comprises two eccentrically rotating gears (inner and outer rotor), with the medium being conveyed through the changed displacement space in the respective spaces between the rotors. Such pumps comprise the pump itself as the main components, as well as an electric motor for driving the pump, separated from each other by at least one bearing plate.

[0003] The motor and pump shafts for driving the pump can form a single, integrated component. This shared shaft incorporates bearings to absorb forces acting during operation, particularly radial forces. Typically, a fixed bearing is provided on the drive side (the so-called A-side) and a floating bearing on the non-drive side (B-side), e.g., in the form of a ball bearing. The disadvantage, however, is that such a bearing concept, especially one comprising a ball bearing, requires a relatively large amount of space, which can cause problems in applications with limited installation space. The assembly of such a device also entails greater complexity in this case.

[0004] DE 196 33 169 A1 describes an electric motor / pump unit with at least one bearing for supporting a motor shaft in a motor housing, and with a pump (piston pump) attached to the electric motor, which has at least one rolling bearing for supporting a pump shaft in a pump housing. The two shafts are connected to each other by means of a force-locking transmission element. The transmission element has a sleeve shape and has resilient sections that clamp the two shafts against each other.

[0005] DE 10 2008 060 875 A1 discloses a motor-pump arrangement comprising a gear pump with a pump motor as an internal rotor and a housing with a base and a bearing cover. A stator, a pump cover for the pump motor, and a pump cover are arranged in the housing. The pump rotor and a pump ring are arranged between the pump covers. A common shaft 40 is mounted in the pump cover and the bearing cover. The rotor of the pump motor is seated on the shaft 40. At the same time, the pump rotor is firmly connected to the shaft. The rotor of the brushless DC motor and the rotor of the positive displacement pump are rigidly mounted on a shaft and housed in two shaft bearings 4 and 5. The distance between the shaft bearings 4 and 5 is equal to the height of the rotor. The shaft bearings 4, 5, 45, and 46 are designed as needle bearings or as hydrodynamically lubricated plain bearings.The housing of the gears and the stator of the pump are rigidly connected to each other and the common shaft is mounted on one side of the stator of the DC motor and on the other side in the housing of the gears and / or the n pole pairs of the DC motor are radially aligned.

[0006] WO 94 / 27 045 A1 relates to a motor pump unit comprising a motor housing and a pump housing which are connected to one another by means of screws. An armature shaft 4 extends through both housings. The pump housing is a block with several bores which, among other things, also contain pump pistons. Within the motor housing, the armature shaft 4 carries an armature with windings. Furthermore, a commutator is provided via which the windings are supplied with current. Permanent magnets are arranged in the motor housing. The shaft 4 is supported at three points. The first bearing or auxiliary bearing 10 consists of a barrel-shaped pin 11 which is fastened by means of a rivet 12 to the base 13 of the motor housing which faces away from the pump housing. The second bearing or main bearing 15 is designed as a ball bearing and is inserted in a recess 17 in the motor housing or in the bearing plate 25 which opens outwards.The recess 17 is not very deep, so that the bearing 15 protrudes from the motor housing 1 over most of its length. Further out, the armature shaft 4 is held in another bearing (pump bearing 19), which is designed as a needle bearing. This bearing is located entirely within a bore in the pump housing.

[0007] DE 10 2010 054 250 A1 discloses a hydraulic control system with a control plate arrangement and one with a hydraulic delivery device for delivering a hydraulic medium, wherein the hydraulic delivery device is integrated into the control plate arrangement and comprises a first hydraulic pump 15 and a second hydraulic pump 16. A common pump shaft 20 is connected in a rotationally fixed manner to a pump gear 24 of the first hydraulic pump 15 via a transverse pin 23. The pump gear 24 driven by the pump shaft 20 meshes with another pump gear 28 of the first hydraulic pump 15. The other pump gear 28 is connected in a rotationally fixed manner to a pump axle 30 by another transverse pin 29. The pump axle 30, like the pump shaft 20, is rotatably mounted in two bearing brackets 25 and 26. The two pump gears 24, 28 are mounted in the first control plate by means of the bearing brackets 25, 26.The second hydraulic pump 16 is supported by a pillow block bearing 34 which comprises a pillow block bearing sleeve which is fastened at one end in the first control plate.

[0008] US 2016 / 0186746 A1 discloses a liquid pump comprising a container, a shaft, a bearing, a pump mechanism, a storage chamber, and a liquid supply line. The shaft rotates in the container and is supported by the bearing. The pump mechanism pumps the liquid. The storage chamber is located outside the pump mechanism and stores the liquid. The liquid supply line carries the stored liquid to the bearing.

[0009] US 6,732,631 B1 relates to a needle bearing for use in a pump. It consists of an inner ring designed as an eccentric sleeve, needles, and an outer ring with radially inward-facing rims on both ends. One rim secures the axial position of the needles and the outer ring by engaging with the inner ring by fitting over one end face of the inner ring. In the pump unit, the needle bearing is arranged at an axial distance from a roller bearing on a drive motor shaft. The rim of the outer ring engages this distance.

[0010] CN 1 05 736 372 A discloses a rotary compressor with a compression mechanism and a motor in a sealed housing. The motor consists of a stator and a rotor. The compression mechanism includes an air cylinder, a crankshaft, main and auxiliary bearings, and two rolling bearings. An eccentrically running piston is located in the compression chamber. The crankshaft has a main shaft for the rotor, an eccentric shaft for the piston, and an auxiliary shaft. The rolling bearings are arranged between the bearings and the shafts. At least one of the bearings has a sliding fit with the crankshaft.

[0011] US 10,160,276 B2 relates to a hydraulic control system comprising a control plate assembly and a hydraulic transport device for transporting a hydraulic medium. The invention is characterized in that the hydraulic transport device is integrated into the control plate assembly.

[0012] US 2013 / 0 052 058 A1 describes a pump body consisting of a pump housing and a pump plate in front of the pump housing. A motor housing is attached to the rear end of the pump housing and houses a pump drive motor. A bearing assembly supporting a motor shaft includes a first bearing in a blind hole at the rear of the pump plate, supporting the front end of the motor shaft, and a second bearing disposed radially inward of a cylindrical bearing support in the pump housing, supporting the central portion of the motor shaft. A pump rotor is disposed between the first and second bearings.

[0013] DE 41 34 964 C2 shows a scroll compressor with a pump for lubricating a shaft bearing.

[0014] DE 10 2013 007 065 B4 relates to a contact surface consisting of at least two components, one of which is made of titanium, aluminum, or their alloys, and the other of a softer material. This can include screw or clamp connections, in particular plain bearing connections.

[0015] DE 82 21 673 U1 b refers to a coupling with two bearings.

[0016] The invention is therefore based on the object of specifying a bearing arrangement for a pump motor which is designed to save installation space and enables simple assembly.

[0017] According to the invention, this object is achieved by the subject matter of claim 1.

[0018] A bearing assembly for a pump motor is proposed, comprising a pump housing, a pump head, and at least one pump rotor, a motor housing assembly with a stator and a rotor arranged around a motor shaft (or a stator and a rotor are arranged around the motor shaft), and a bearing shield arranged between the motor housing assembly and the pump housing. A fixed bearing is provided in the bearing shield on the motor housing assembly side, and a secondary bearing is provided in the pump head for supporting the motor shaft. The fixed bearing is designed as a ball bearing in the motor on the motor housing assembly side.The secondary bearing comprises a first and a second bearing element and the second bearing element is pressed into the first bearing element, wherein the secondary bearing has a first bearing surface and a second bearing surface, wherein an outer surface of the first bearing surface bears against the at least one pump rotor, wherein an inner surface of the second bearing surface bears against the motor shaft and wherein the first and the second bearing element have different materials from one another.

[0019] The advantage is that the secondary bearing, which supports the motor or motor shaft, requires no additional or separate installation space, as the secondary bearing is fully integrated into the pump motor. The original B-side ball bearing is therefore no longer required.

[0020] The secondary bearing comprises a first and / or a second bearing element.

[0021] The second bearing element is pressed into the first bearing element. Alternatively, the second bearing element can also be inserted or glued into the first bearing element, or secured by another method known to those skilled in the art.

[0022] According to an advantageous embodiment, the secondary bearing is provided for supporting the at least one pump rotor. The pump rotor is designed as an outer rotor and / or an inner rotor or comprises the outer rotor and / or the inner rotor. The secondary bearing supports both the pump rotor and the motor shaft.

[0023] In a further advantageous embodiment, the secondary bearing is designed as a plain bearing. However, the secondary bearing can also comprise a plain bearing; for example, several interconnected bearings can be provided within the secondary bearing.

[0024] According to a further advantageous embodiment, an outer surface of the first bearing element rests against the at least one pump rotor (for example, against the inner surface of the pump rotor). An inner surface of the second bearing element rests against the motor shaft. The diameter of the first bearing element of the secondary bearing is larger than the diameter of the second bearing element of the secondary bearing. This can also apply to an opening or a bore in the bearing element if the secondary bearing is designed, for example, as a bushing. In this case, the diameter of the opening or bore of the first bearing element is larger than the diameter of the opening or bore of the second bearing element of the secondary bearing. In addition, the first and / or second bearing element have an opening on one and / or both end faces. However, the first and / or second bearing element can also be closed on one end face.

[0025] In a further advantageous embodiment, a press fit is provided between the secondary bearing and the pump head. The secondary bearing absorbs radial forces from the pump by being pressed into the pump head. Thus, only the weight of the motor shaft and no other forces act on the secondary bearing.

[0026] The secondary bearing as such, or in particular the first bearing element, are designed as a stepped hollow cylinder. Due to the stepped design, the secondary bearing and the first bearing element fit more precisely against the pump head. However, the secondary bearing as such, or in particular the first bearing element, can also have other designs known to those skilled in the art.

[0027] In a further advantageous embodiment, the first bearing element consists of a bushing preferably made of a sintered material, preferably hardened sintered steel. By using hardened sintered steel for the first bearing element, deformation of the first bearing element during pressing into the pump head is avoided. However, the first bearing element can also be made of other suitable materials known to those skilled in the art.

[0028] According to a further advantageous embodiment, the second bearing element consists of a bushing preferably made of a sintered material, preferably sintered steel or sintered bronze, and / or is preferably soaked or impregnated. However, the second bearing element can also be made of other suitable materials known to those skilled in the art.

[0029] Soaking or impregnating the first and / or second bearing element enables dry running. The first and second bearing elements can be impregnated separately or together.

[0030] The design of the secondary bearing consisting of a first and a second bearing element enables a targeted material selection according to the application.

[0031] In a further advantageous embodiment, the pump is a positive displacement pump, preferably a gear pump, in particular a gerotor pump.

[0032] The invention will be explained in more detail below using exemplary embodiments with reference to the accompanying drawings. They show: Fig. 1 a sectional view of the pump according to the invention, Fig. 2 a sectional view of a one-piece secondary bearing, and Fig. 3 a sectional view of a two-part secondary bearing.

[0033] Fig. 1 shows a sectional view of a pump according to one embodiment, in the example a gerotor pump driven by an electric motor with a bearing arrangement (1) for a pump motor comprising a pump housing (2), a pump head (3) and at least one pump rotor (4), a motor housing arrangement (5) with a stator (6) and a rotor (7), which is arranged around a motor shaft (8), and a bearing plate (9) which is arranged between the motor housing arrangement (5) and the pump housing (2), wherein a fixed bearing (10) on the side of the motor housing arrangement (5) in the bearing plate (9) and a secondary bearing (11) in the pump head (3) are provided for supporting the motor shaft (8). The secondary bearing (11) comprises a first bearing element (12) and a second bearing element (13), which are pressed into one another or otherwise fastened to one another.The outer surface (14) of the first bearing element (12) rests against the at least one pump rotor (4), and the inner surface (15) of the second bearing element (13) rests against the motor shaft (8). The second bearing (11) has a first bearing surface (18) and a second bearing surface (19). The outer surface (20) of the first bearing surface (18) rests against the at least one pump rotor (4), and the inner surface (21) of the second bearing surface (19) rests against the motor shaft (8). The at least one pump rotor (4) comprises an inner rotor (16) and an outer rotor (17), wherein the inner rotor (16) rests against the outer surface (14) of the first bearing element (12).

[0034] Fig. Figure 2 shows a sectional view of an embodiment with a one-piece secondary bearing (11) that is pressed into a pump head (3) and is provided for supporting the at least one pump rotor (4). The secondary bearing (11) bears against the at least one pump rotor (4) with a first bearing surface (18) and against the motor shaft (8) with a second bearing surface (19).

[0035] Fig. Figure 3 shows a sectional view of a two-part secondary bearing (11) that is pressed into a pump head (3) and provided for supporting the at least one pump rotor (4). The secondary bearing (11) comprises a first and a second bearing element (12, 13), wherein the second bearing element (13) is pressed into the first bearing element (12). An outer surface (14) of the first bearing element (12) bears against the at least one pump rotor (4), and an inner surface (15) of the second bearing element (13) bears against the motor shaft (8). List of reference symbols 1 bearing arrangement 2 pump housings 3 Pump head 4 Pump rotor 5 Motor housing arrangement 6 Stator 7 Rotor 8 Motor shaft 9 Bearing shield 10 fixed bearings 11 Second camp 12 First bearing element 13 Second bearing element 14 Outer surface of the first bearing element 15 Inner surface of second bearing element 16 inner rotor 17 Outer rotor 18 First storage area 19 Second storage area 20 Outside area first storage area 21 Inner surface of second storage area

Claims

[1] Bearing arrangement (1) for a pump motor comprising a pump housing (2), a pump head (3) and at least one pump rotor (4), a motor housing arrangement (5) with a stator (6) and a rotor (7) arranged around a motor shaft (8), and a bearing plate (9) arranged between the motor housing arrangement (5) and the pump housing (2), a fixed bearing (10) on the side of the motor housing arrangement (5) in the bearing plate (9) and a second bearing (11) in the pump head (3) for supporting the motor shaft (8), wherein the second bearing (11) comprises a first and a second bearing element (12, 13) and the second bearing element (13) is pressed into the first bearing element (12), wherein the second bearing (11) has a first bearing surface (18) and a second bearing surface (19), wherein an outer surface (20) of the first bearing surface (18) on the at least one pump rotor (4) is present,wherein an inner surface (21) of the second bearing surface (19) bears against the motor shaft (8) and wherein the first and second bearing elements (12, 13) have different materials from one another. [2] Bearing arrangement according to claim 1, wherein the second bearing (11) is provided for supporting the at least one pump rotor (4). [3] Bearing arrangement according to claim 1 or 2, wherein the second bearing (11) is designed as a plain bearing. [4] Bearing arrangement according to claim 1, wherein an outer surface (14) of the first bearing element (12) bears against the at least one pump rotor (4) and wherein an inner surface (15) of the second bearing element (13) bears against the motor shaft (8). [5] Bearing arrangement according to one of the preceding claims, wherein a press fit is provided between the secondary bearing (11) and the pump head (3). [6] Bearing arrangement according to one of the preceding claims, wherein the first bearing element (12) consists of a bushing preferably made of a sintered material, preferably of hardened sintered steel, and wherein the second bearing element (13) consists of a bushing preferably made of a sintered material, preferably of sintered steel or sintered bronze and / or is preferably soaked or impregnated. [7] Pump with a bearing arrangement according to the preceding claims, wherein the pump is a positive displacement pump, preferably a gear pump, in particular a gerotor pump.

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