DE102021133692A1 - Automotive electric fluid pump - Google Patents

Abstract

The invention relates to an electric motor vehicle fluid pump (10), in particular the invention relates to an electric water pump for supplying a motor vehicle cooling circuit. The electric motor vehicle fluid pump (10) according to the invention comprises a fixed containment shell (22) which fluidly 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, with the rotor axis (14) being mounted directly or indirectly in the containment shell (22) in a non-positive manner by means of a conical seat connection (20). This allows the containment shell (22) to be manufactured relatively inexpensively and also allows the rotor axis (14) to be assembled in a particularly simple and inexpensive manner.

Description

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

Motor vehicle fluid pumps are mostly used in pressure circuits in which the media are predominantly in the liquid phase, such as in cooling or lubricating circuits, but can also be used in pressure circuits in which the medium is partly liquid and partly gaseous, such as in flushing circuits of fuel tanks.

Such electrically driven motor vehicle fluid pumps include an electric drive motor with an electronic commutation, which makes it possible to separate the motor rotor and the motor stator fluidically by arranging a mostly metallic can between the motor rotor and motor stator, which runs through the air gap between the motor rotor and motor stator. In this way, a wet space, in which the motor rotor is arranged, and a dry space, in which the motor stator and the power electronics are arranged, are formed within the pump housing.

The motor rotor, which is preferably arranged inside the containment shell, is often rotatably and slidably mounted on a fixed rotor axis. In order to mount the rotor axis, a cylindrical bearing bush on the bottom of the containment shell is usually used, into which the rotor axis is pressed or glued. For this purpose, the bearing bush can either be in the form of a separate component which is welded to the containment shell, for example, or the bearing bush can be integrated into the containment shell in one piece.

Here is an example DE 10 2007 016 255 B4 mentioned, which discloses a containment shell with an integrated collar-like and cylindrical bearing bush, into which a cylindrical rotor axis is inserted. The motor rotor, which is non-rotatably connected to a pump rotor, is rotatably mounted on the fixed rotor axis and is driven electromagnetically by the motor stator.

In particular when the rotor axis is pressed into the bearing bush, high demands are placed on the surfaces of the components to be joined with regard to the diameter tolerances and the surface properties. The use of a glued connection between the rotor axis and the bearing bush allows coarser tolerances for the components to be joined than with a cylindrical press connection, but an additional work step is necessary for gluing in the rotor axis. Furthermore, due to the additionally required adhesive, higher material costs arise than with a press connection.

The present invention is therefore based on the object of creating an electric motor vehicle fluid pump that can be produced particularly cost-effectively.

This object is achieved with an electric motor vehicle fluid pump according to the invention with the features of claim 1.

An electric motor vehicle fluid pump according to the invention comprises a fixed containment shell which is arranged within a pump housing which preferably consists of at least two parts. The containment shell fluidly separates a motor rotor and a motor stator of an electric motor that drives a pump rotor of the electric motor vehicle fluid pump from one another. The containment shell runs 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. As a result, a rotor-side wet space is formed within the pump housing, which is preferably filled with the pumped medium. The wet space is fluidically separated from the dry space on the stator side by means of the containment shell, as a result of which the moisture-sensitive motor stator does not come into contact with the pumped medium. The can is preferably made of a metallic and non-magnetic material that does not affect the magnetic field generated by the motor stator and driving the motor rotor.

The motor rotor driving the pump rotor is rotatably mounted on a fixed rotor axis. For this purpose, the motor rotor can have, for example, a plain bearing bushing which is connected to the motor rotor in a torque-proof manner and which runs directly on the preferably metallic rotor axis. Alternatively, the motor rotor can be mounted on the rotor axis via a roller bearing, for example. The rotor axis is mounted directly or indirectly in the containment shell by means of a conical seat connection, i.e. the rotor axis is fixed in a corresponding rotor axis mount via a friction joint connection. The rotor axle receptacle can be, for example, a separate bearing bush connected to the containment shell.

Preferably, the rotor axle mount is formed in one piece with the containment shell, ie the rotor axle mount is integrated into the containment shell, resulting in an additional assembly step for connecting a separate bearing bush to the gap pot omitted. As a result, the assembly process of the electric motor vehicle fluid pump is particularly simple and inexpensive, so that the overall costs of the electric motor vehicle fluid pump can be significantly reduced compared to the known pumps from the prior art.

In a preferred embodiment of the invention, the containment shell has a conical rotor axle receptacle. Furthermore, at least one end section, i.e. a section on one of the two axial ends of the rotor axle, is conical in a corresponding manner, i.e. the cone of the rotor axle essentially corresponds to the cone in the rotor axle holder in terms of its basic dimensions such as length, diameter and angle, so that the Pressing the conical end section of the rotor axis into the conical rotor axis mount forms a conical seat or cone press connection, the frictional connection of which secures the rotor axis axially and rotationally in the rotor axis mount, so that a non-rotatable mounting of the rotor axis in the rotor axis mount is ensured.

The containment shell is preferably designed as a deep-drawn sheet metal part. This enables the containment shell to be produced in a relatively simple and cost-effective manner. Particularly preferably, the rotor axle receptacle is designed as a deep-drawn annular collar, which preferably extends axially, starting from the bottom of the containment shell, in the direction of the interior of the containment shell. The collar is shaped in such a way that a conical inner wall is formed which tapers inwards in the direction of the bottom of the can. The rotor axle receptacle can only be produced at all by means of deep-drawing due to its conicity, since at least a slight draft angle is necessary in order to be able to remove the deep-drawing mandrel again after the deep-drawing process. By using the deep-drawing process, the rotor axle mount can therefore be produced relatively easily in one work step and, due to the accuracy sufficient for a conical seat connection, allows the conical end section of the rotor axle to be directly accommodated. Due to the conicity of the surfaces to be joined, both the rotor axle receptacle and the rotor axle can be tolerated more roughly with regard to their manufacturing tolerances. In contrast to a cylindrical press connection, tolerance-related dimensional differences, in particular differences in diameter, between the two parts to be joined can be relatively easily compensated for with a cone press connection by progressively pushing the cones into each other until they are pressed, which means that significantly less waste is produced during production than when using a cylindrical interference fit.

In a preferred embodiment of the invention, the second end section of the rotor axis, ie the section at the other axial end of the rotor axis, is designed in an identical manner to the first end section of the rotor axis. This enables a simpler assembly method for the electric motor vehicle fluid pump, since the prefabricated axle does not first have to be oriented accordingly before assembly, but can be pressed into the rotor axle receptacle with any axial end.

In a particularly preferred embodiment of the invention, the cone angle of the cone press connection, which is decisively defined by the cone angle of the rotor axis end section, is less than 10°. The cone angle is particularly preferably between 3° and 7°, which means that the rotor axis and the rotor axis holder can be joined relatively easily and yet a high frictional connection is generated between the joining surfaces, which ensures a particularly secure fit of the rotor axis in the rotor axis holder.

In an advantageous embodiment of the invention, the base of the rotor axle receptacle does not protrude axially beyond the base of the containment shell in the direction of the exterior of the containment shell. Since the bottom of the can is often used to cool power electronic components for controlling the electric motor, contact over a large area between the bottom of the can and a printed circuit board carrying the power electronics is preferred. Thus, the rotor axle mount should not protrude in the direction of the printed circuit board beyond the base plane of the can bottom, which is formed by the end face of the can surrounding the rotor axle mount.

The tapered press connection between the rotor axle and the containment shell enables the use of a deep-drawn containment shell with a deep-drawn rotor axle mount integrated into the containment shell, which accommodates the rotor axle directly. As a result, the electric motor vehicle fluid pump according to the invention can be produced particularly cost-effectively and is easy to assemble.

• 1 eine schematische Darstellung einer erfindungsgemäßen elektrischen Kraftfahrzeug-Fluidpumpe in einem Längsschnitt entlang der Rotorachse, und
• 2 eine vergrößerte Detailansicht der Kegelsitzverbindung der in 1 gezeigten elektrischen Kraftfahrzeug-Fluidpumpe.

A preferred exemplary embodiment of the electric motor vehicle fluid pump according to the invention is explained in more detail below with reference to drawings. Show it:

• 1 a schematic representation of an electric motor vehicle fluid pump according to the invention in a longitudinal section along the rotor axis, and
• 2 an enlarged detailed view of the conical seat connection in 1 automotive electric fluid pump shown.

1 shows an electric water circulation 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-like 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 wheel 161, which is rotatably arranged in the pump chamber 15 and works according to the centrifugal principle. The water circulation pump 10 also includes 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 driven electromagnetically by a motor stator 34 surrounding the motor rotor 32 . A deep-drawn containment shell 22 made of austenitic sheet steel is arranged in an annular gap running between the motor rotor 32 and the motor stator 34.

In addition to the motor stator 34 , a printed circuit board 40 is arranged in the dry space, which is equipped with power electronic components for controlling the electric motor 30 . The printed circuit board 40 is arranged parallel and in an adjacent manner, i.e. in a large-area heat-transferring contact with the can bottom 222, so that the water circulating in the wet room dissipates the heat generated by the power electronic components and transferred to the can bottom 222.

The containment shell comprises a conical rotor axle receptacle 221 which is formed by a deep-drawn annular collar 223 integrated into the containment shell 22 and protruding into the interior 224 of the containment shell. A metallic rotor axle 14 is pressed into the rotor axle receptacle 221, which has conical end sections 141, 142 at both of its axial ends, both of which have a cone angle a of 5°, their base diameter d and their cone length L, which is at least 1.5 times the Base diameter d corresponds essentially to the cone in the rotor axle receptacle 221, with the first conical end section 141 being pressed into the conical rotor axle receptacle 221 in such a way that a tapered seat connection 20 (see also 2 ) is formed, which frictionally supports the rotor axis 14 in the containment shell 22, so that the rotor axis 14 is fixed axially and secured against rotation. The rotor axle receptacle 221 does not protrude axially in the direction of the printed circuit board 40 beyond the containment shell base 222, so that the printed circuit board 40 can be placed relatively close to the containment shell base 222, which enables a relatively large-area contact between the printed circuit board 40 and the containment shell base 222, which ensures good heat dissipation .

The pump rotor 16 and the motor rotor 32 are connected to one another in a rotationally fixed manner, with the motor rotor 32 being rotatably mounted indirectly on the rotor axis 14 via a plastic plain bearing bushing 162 of the pump rotor 16 . In addition, the pump rotor 16 is secured axially at its pump wheel-side axial end by an axially acting plain bearing ring 45 seated in the pump cover 122 . The motor rotor 32 driven by the motor stator 34 in turn drives the pump rotor 16 with the pump wheel 161, as a result of which water is sucked in axially through an inlet channel 11 running in the suction connection 17 into the pump wheel 161 and due to the centrifugal force in the radial direction into the volute 151 of the pump chamber 15 is ejected.

The conical press connection 20 represents a relatively secure connection between the rotor axle 14 and the containment shell 22 that is easy to assemble Production costs for the water circulation pump 10 according to the invention result.

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• DE 102007016255 B4 [0005]

Claims (8)

Automotive electric fluid pump (10) with a stationary can (22) which fluidly 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 pump rotor (16) driving motor rotor (32) of the electric motor (30) is rotatably mounted, wherein the rotor axis (14) is mounted directly or indirectly in the containment shell (22) in a non-positive manner by means of a conical seat connection (20). Automotive electric fluid pump (10) according to claim 1 , wherein the containment shell (22) has a conical rotor axle mount (221), and at least one end section (141) of the rotor axle (14) pressed into the rotor axle mount (221) is correspondingly conical, so that the rotor axle (14) is non-rotatably in the rotor axle mount (221) is mounted. Electric motor vehicle fluid pump (10) according to one of the preceding claims, wherein the containment shell (22) is designed as a deep-drawn sheet metal component. Electric motor vehicle fluid pump (10) according to one of the preceding claims, wherein the rotor axle receptacle (221) is formed in one piece with the containment shell (22). Automotive electric fluid pump (10) according to any one of claims 2 until 4 , wherein the rotor axle receptacle (221) is designed as a deep-drawn collar (223) projecting axially in relation to the base (222) of the containment shell (22) in the direction of the interior of the containment shell (224). Motor vehicle electric fluid pump (10) according to one of the preceding claims, wherein the second end section (142) of the rotor axis (14) is formed in an identical manner to the first end section (141) of the rotor axis (14). An automotive electric fluid pump (10) according to any one of the preceding claims, wherein the taper angle (a) of the taper interference fit (20) is less than 10° and preferably between 3° and 7°. Automotive electric fluid pump (10) according to any one of Claims 5 until 7 , wherein the base (226) of the rotor axle receptacle (221) does not protrude axially in the direction of the containment shell exterior (225) beyond the containment shell base (222).

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