Electric automotive fluid pump with conical press connection between rotor shaft and containment shell

Abstract

An electric motor vehicle fluid pump (10) comprising a stationary containment shell (22) which fluidically separates a motor rotor (32) and a motor stator (34) of an electric motor (30) driving a pump rotor (16), and a stationary rotor shaft (14) on which the motor rotor (32) of the electric motor (30) driving the pump rotor (16) is rotatably mounted, wherein the containment shell (22) is designed as a deep-drawn sheet metal component, characterized in that the rotor shaft (14) is held on one side in the containment shell (22) such that it is directly or indirectly frictionally mounted in the containment shell (22) by means of a conical seat connection (20), wherein the containment shell (22) has a conically designed rotor shaft receptacle (221), and the conical seat connection (20) is formed by pressing a conical first end section (141) of the rotor shaft (14) into the conical Rotor shaft mount (221) is formed.

Description

[0001] The invention relates to an electric motor vehicle fluid pump, in particular to an electric water pump for supplying a motor vehicle cooling circuit.

[0002] Automotive fluid pumps are mostly used in pressure circuits where the media are predominantly in liquid phase, such as in cooling or lubrication circuits, but can also be used in pressure circuits where the medium is partly liquid and partly gaseous, such as in fuel tank flushing circuits.

[0003] Such electrically driven automotive fluid pumps comprise an electric drive motor with electronic commutation, which enables fluidic separation of the motor rotor and motor stator by placing a mostly metallic containment shell between the motor rotor and motor stator, extending through the air gap between them. In this way, a wet chamber, in which the motor rotor is located, and a dry chamber, in which the motor stator and power electronics are located, are formed within the pump housing.

[0004] The motor rotor, preferably located inside the containment shell, is often rotatably mounted on a fixed rotor shaft. To support the rotor shaft, a cylindrical bearing bushing is typically used at the bottom of the containment shell, into which the rotor shaft is pressed or bonded. The bearing bushing can either be a separate component, for example, welded to the containment shell, or it can be integrally integrated into the containment shell.

[0005] As an example, DE 10 2007 016 255 B4 may be mentioned, which discloses a containment pot with an integrated collar-like and cylindrical bearing bushing into which a cylindrical rotor shaft is inserted. The motor rotor, which is rotationally fixed to a pump rotor, is rotatably mounted on the stationary rotor shaft and is electromagnetically driven by means of the motor stator.

[0006] Especially when the rotor shaft is pressed into the bearing bushing, stringent requirements are placed on the diameter tolerances and surface finish of the components being joined. While an adhesive bond between the rotor shaft and bearing bushing allows for greater tolerances in the components being joined than a cylindrical press fit, it requires an additional step for bonding the rotor shaft. Furthermore, the additional adhesive required results in higher material costs compared to a press fit.

[0007] The present invention is therefore based on the objective of creating a particularly cost-effective electric motor vehicle fluid pump.

[0008] This problem is solved with an electric motor vehicle fluid pump according to the invention having the features of claim 1.

[0009] An electric vehicle fluid pump according to the invention comprises a stationary containment shell arranged within a preferably at least two-part pump housing. The containment shell fluidically separates a motor rotor and a motor stator of an electric motor that drives a pump rotor of the electric vehicle fluid pump. The containment shell extends in the so-called air gap between the motor rotor, which is preferably arranged on the inside of the containment shell, and the motor stator, which is preferably arranged on the outside of the containment shell and surrounds the motor rotor. This creates a wet chamber on the rotor side within the pump housing, which is preferably filled with the pumped medium. The wet chamber is fluidically separated from the dry chamber on the stator side by means of the containment shell, thus preventing the moisture-sensitive motor stator from coming into contact with the pumped medium.The containment pot is preferably made of a metallic and non-magnetic material that does not influence the magnetic field generated by the motor stator and driving the motor rotor.

[0010] The motor rotor driving the pump rotor is rotatably mounted on a stationary rotor shaft. For this purpose, the motor rotor can, for example, have a sliding bearing bushing that is rotationally fixed to the motor rotor and runs directly on the preferably metallic rotor shaft. Alternatively, the motor rotor can, for example, be mounted on the rotor shaft via a rolling bearing. The rotor shaft is frictionally secured in the containment shell by means of a tapered seat connection, either directly or indirectly; that is, the rotor shaft is fixed in a corresponding rotor shaft receptacle via a frictional connection. The rotor shaft receptacle can, for example, be a separate bearing bushing connected to the containment shell.

[0011] Preferably, the rotor shaft mount is formed integrally with the containment shell, i.e., the rotor shaft mount is integrated into the containment shell, thus eliminating an additional assembly step for connecting a separate bearing bushing to the containment shell. This makes the assembly process of the electric automotive fluid pump particularly simple and cost-effective, so that the overall cost of the electric automotive fluid pump can be significantly reduced compared to known pumps from the prior art.

[0012] In a preferred embodiment of the invention, the containment pot has a conically shaped rotor shaft receptacle. Furthermore, at least one end section, i.e., a section at one of the two axial ends of the rotor shaft, is conically shaped in a corresponding manner; that is, the cone of the rotor shaft corresponds essentially to the cone in the rotor shaft receptacle with respect to its fundamental dimensions such as length, diameter, and angle, so that by pressing the conical end section of the rotor shaft into the conical rotor shaft receptacle, a conical seat or conical press fit is formed, the frictional connection of which secures the rotor shaft axially and rotationally in the rotor shaft receptacle, thus ensuring a rotationally fixed bearing of the rotor shaft in the rotor shaft receptacle.

[0013] The containment pot is preferably designed as a deep-drawn sheet metal part. This allows for relatively simple and cost-effective manufacturing of the containment pot. The rotor shaft receptacle is particularly preferably designed as a deep-drawn, annular collar that extends axially from the containment pot base towards the interior of the containment pot. The collar is shaped such that a conical inner wall is formed, which tapers inwards towards the containment pot base. The rotor shaft receptacle can only be manufactured by deep drawing due to its conic shape, since at least a slight draft angle is generally necessary to allow the deep-drawing mandrel to be removed after the deep-drawing process.By using the deep-drawing process, the rotor shaft mount can be manufactured relatively easily in a single operation. Due to the accuracy sufficient for a tapered seat connection, the conical end section of the rotor shaft can be directly accommodated. The taper of the surfaces to be joined allows for coarser manufacturing tolerances for both the rotor shaft mount and the rotor shaft itself. In contrast to a cylindrical press fit, tolerance-related dimensional differences, particularly diameter differences, between the two parts to be joined can be relatively easily compensated for in a tapered press fit by progressively sliding the cones together until they are pressed. This results in significantly less scrap during production compared to using a cylindrical interference fit.

[0014] In a preferred embodiment of the invention, the second end section of the rotor shaft, i.e., the section at the other axial end of the rotor shaft, is designed identically to the first end section of the rotor shaft. This enables a simpler assembly method for the electric automotive fluid pump, since the prefabricated shaft does not need to be oriented accordingly before assembly, but can be pressed into the rotor shaft receptacle with any axial end.

[0015] In a particularly preferred embodiment of the invention, the cone angle of the conical press fit, which is largely defined by the cone angle of the rotor shaft end section, is less than 10°. Particularly preferably, the cone angle lies between 3° and 7°, which allows the rotor shaft and the rotor shaft receptacle to be joined relatively easily while still generating a high degree of frictional engagement between the joining surfaces, ensuring a particularly secure fit of the rotor shaft in the rotor shaft receptacle.

[0016] In an advantageous embodiment of the invention, the base of the rotor shaft receptacle does not project axially beyond the base of the containment shell. Since the containment shell base is frequently used to cool power electronic components for controlling the electric motor, a large contact area between the containment shell base and a printed circuit board supporting the power electronics is preferred. Therefore, the rotor shaft receptacle should not project beyond the base plane of the containment shell base, which is formed by the end face of the containment shell surrounding the rotor shaft receptacle, towards the printed circuit board.

[0017] The tapered press fit between the rotor shaft and the containment shell allows the use of a deep-drawn containment shell with an integrated deep-drawn rotor shaft receptacle that directly accommodates the rotor shaft. This makes the electric automotive fluid pump according to the invention particularly cost-effective to manufacture and easy to assemble.

[0018] A preferred embodiment of the electric automotive fluid pump according to the invention is explained in more detail below with reference to the drawings. The drawings show: Fig. 1 a schematic representation of an electric motor vehicle fluid pump according to the invention in a longitudinal section along the rotor axis, and Fig. 2 an enlarged detail view of the conical seat connection of the in Fig. 1 electric automotive fluid pump shown.

[0019] Fig. Figure 1 shows an electric water circulating pump 10 for supplying an auxiliary cooling circuit of a motor vehicle. The water circulating pump 10 comprises a two-part pump housing 12 with a pot-shaped motor housing 121 and a pump cover 122, which at least partially forms a pump chamber 15 with a volute 151 and includes an axial suction port 17. Furthermore, the water circulating pump 10 comprises a pump rotor 16 with a pump impeller 161, which is rotatably arranged in the pump chamber 15 and operates according to the centrifugal principle. The water circulating pump 10 also comprises an electronically commutated electric motor 30, which drives the pump rotor 16. The electric motor 30 comprises an internal rotatable motor rotor 32, which can be electromagnetically driven by a motor stator 34 that surrounds the motor rotor 32.In an annular gap running between the motor rotor 32 and the motor stator 34, a deep-drawn containment pot 22 made of austenitic sheet steel is arranged, which fluidically separates the motor rotor 32 from the motor stator 34 and thereby forms a rotor-side wet chamber and a stator-side dry chamber within the pump housing 12.

[0020] In addition to the motor stator 34, a circuit board 40 is arranged in the dry chamber, which is equipped with power electronic components for controlling the electric motor 30. The circuit board 40 is arranged parallel to and adjacent to, i.e., in large-area heat-transferring contact with, the containment pot base 222, so that the water circulating in the wet chamber dissipates the heat generated by the power electronic components and transferred to the containment pot base 222.

[0021] The containment shell comprises a conical rotor shaft receptacle 221 formed by a deep-drawn, annular collar 223 integrated into the containment shell 22 and projecting into the interior 224 of the containment shell. A metallic rotor shaft 14 is pressed into the rotor shaft receptacle 221, the shaft having conical end sections 141, 142 at its two axial ends. Both end sections, with respect to their cone angle α of 5°, their base diameter d, and their cone length L, which is at least 1.5 times the base diameter d, essentially correspond to the cone in the rotor shaft receptacle 221. The first conical end section 141 is pressed into the conical rotor shaft receptacle 221 such that a conical seat connection 20 (see also Fig.2) is formed, which positively locks the rotor shaft 14 in the containment pot 22, so that the rotor shaft 14 is axially fixed and secured against rotation. The rotor shaft receptacle 221 does not project axially beyond the containment pot base 222 in the direction of the circuit board 40, so that the circuit board 40 can be positioned relatively close to the containment pot base 222, thus enabling a relatively large contact area between the circuit board 40 and the containment pot base 222, which ensures good heat dissipation.

[0022] The pump rotor 16 and the motor rotor 32 are rotationally fixed to each other, with the motor rotor 32 being rotatably mounted on the rotor shaft 14 via a plastic sliding bearing bushing 162 of the pump rotor 16. Additionally, the pump rotor 16 is axially secured at its impeller-side axial end by an axially acting sliding bearing ring 45 located in the pump cover 122. The motor rotor 32, driven by the motor stator 34, in turn drives the pump rotor 16 with the impeller 161, whereby water is drawn axially into the impeller 161 through an inlet channel 11 running in the suction port 17 and, due to centrifugal force, is expelled radially into the volute 151 of the pump chamber 15.

[0023] The conical press fit 20 provides a relatively secure and easy-to-assemble connection between the rotor shaft 14 and the containment shell 22. Additionally, the conical press fit 20 allows the rotor shaft receptacle 221 to be formed integrally with the deep-drawn containment shell 22 as a deep-drawn collar 223, resulting in relatively low production costs for the water circulating pump 10 according to the invention. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 102007016255 B4

[0005]

Claims

[1] Electric automotive fluid pump (10) with a stationary split pot (22) which fluidically separates a motor rotor (32) and a motor stator (34) of an electric motor (30) driving a pump rotor (16), and a fixed rotor axis (14) on which the motor rotor (32) of the electric motor (30) driving the pump rotor (16) is rotatably mounted, wherein the rotor axis (14) is supported in the containment pot (22) by means of a conical seat connection (20) either directly or indirectly. [2] Electric motor vehicle fluid pump (10) according to claim 1, wherein the containment shell (22) has a conically shaped rotor shaft receptacle (221), and at least one end section (141) of the rotor shaft (14) pressed into the rotor shaft receptacle (221) is conically shaped in a corresponding manner, so that the rotor shaft (14) is mounted in the rotor shaft receptacle (221) in a rotationally fixed manner. [3] Electric motor vehicle fluid pump (10) according to one of the preceding claims, wherein the containment pot (22) is designed as a deep-drawn sheet metal component. [4] Electric motor vehicle fluid pump (10) according to one of the preceding claims, wherein the rotor shaft receptacle (221) is formed integrally with the containment shell (22). [5] Electric motor vehicle fluid pump (10) according to one of claims 2 to 4, wherein the rotor shaft receptacle (221) is designed as a deep-drawn collar (223) projecting axially towards the interior of the containment pot (224) with respect to the bottom (222) of the containment pot (22). [6] Electric motor vehicle fluid pump (10) according to one of the preceding claims, wherein the second end section (142) of the rotor shaft (14) is designed in an identical manner to the first end section (141) of the rotor shaft (14). [7] Electric motor vehicle fluid pump (10) according to one of the preceding claims, wherein the cone angle (a) of the cone press fit (20) is less than 10° and preferably between 3° and 7°. [8] Electric motor vehicle fluid pump (10) according to one of claims 5 to 7, wherein the bottom (226) of the rotor shaft receptacle (221) does not extend axially towards the outer part of the containment pot (225) beyond the containment pot bottom (222).

Images