Electrically powered motor vehicle fluid pump

Abstract

The invention relates to an electrically driven motor vehicle fluid pump (10), in particular to an electric water pump for motor vehicle cooling circuit supply. The electrically driven motor vehicle fluid pump (10) according to the invention comprises a stationary spacer pot (22) which fluidically separates the motor rotor (32) and the motor stator (34) of an electric motor (30) driving a pump rotor (16) from one another, 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 rotor shaft (14) is indirectly or directly, force-fittingly mounted in the spacer pot (22) by means of a conical seat connection (20). This allows the spacer pot (22) to be produced relatively cost-effectively and further allows the rotor shaft (14) to be mounted particularly simply and cost-effectively.

Description

Technical Field

[0001] This invention relates to an electric fluid pump for motor vehicles, and more particularly, to an electric water pump for supplying cooling circulation to motor vehicles. Background Technology

[0002] Fluid pumps for motor vehicles are mostly used in pressure cycles where the medium is mainly in the liquid phase, such as in cooling or lubricating oil cycles. However, they can also be used in pressure cycles where the medium is partly liquid and partly gaseous, such as in fuel tank flushing cycles.

[0003] This electrically driven fluid pump for motor vehicles includes a drive motor with electronic rectification. A predominantly metal spacer, extending through the air gap between the motor rotor and stator, allows for fluid separation of the motor rotor and stator. In this way, a wet chamber is formed within the pump housing, housing the motor rotor, while a dry chamber houses the motor stator and power electronics.

[0004] Preferably, the motor rotor, disposed inside the spacer tank, is typically rotatably and slidably supported on a fixed rotor shaft. To support the rotor shaft, a cylindrical bearing sleeve is typically used at the bottom of the spacer tank, into which the rotor shaft is pressed or glued. For this purpose, the bearing sleeve can be designed as a separate component, for example, welded to the spacer tank, or it can be integrally integrated into the spacer tank.

[0005] For example, DE 10 2007 016 255 B4 is mentioned herein, which discloses a spacer with an integrated flange-shaped and cylindrical bearing sleeve into which a cylindrical rotor shaft is inserted. A motor rotor, which is anti-rotationally connected to the pump rotor, is rotatably supported on a fixed rotor shaft and is electromagnetically driven by means of a motor stator.

[0006] In particular, when the rotor shaft is pressed into the bearing sleeve, high requirements are placed on the surface of the components to be joined in terms of diameter tolerances and surface properties. Although using adhesive bonding between the rotor shaft and the bearing sleeve allows for coarser tolerances compared to cylindrical press-fit connections, it requires additional steps to bond the rotor shaft. Furthermore, the additional need for adhesive results in higher material costs compared to press-fit connections. Summary of the Invention

[0007] Therefore, the object of the present invention is to complete an electric motor vehicle fluid pump that can be manufactured at a particularly low cost.

[0008] This objective is achieved by an electric motor vehicle fluid pump according to the invention.

[0009] The electric motor vehicle fluid pump according to the invention includes a fixed spacer tank arranged within a pump housing, preferably at least two-piece. The spacer tank fluidly separates the motor rotor and stator of the electric motor, wherein the motor drives the pump rotor of the electric motor vehicle fluid pump. The spacer tank extends in a so-called air gap between the motor rotor, preferably arranged inside the spacer tank, and the motor stator, preferably arranged outside the spacer tank and surrounding the motor rotor. This forms a wet chamber on the rotor side within the pump housing, which is preferably filled with the pump medium. The wet chamber is fluidly separated from the dry chamber on the stator side by means of the spacer tank, thus preventing the humidity-sensitive motor stator from contacting the pump medium. The spacer tank is preferably made of a non-magnetic metallic material that does not affect the magnetic field generated by the motor stator and driving the motor rotor.

[0010] The motor rotor driving the pump rotor is rotatably supported on a fixed rotor shaft. For this purpose, the motor rotor may, for example, have a sliding bearing sleeve connected to the motor rotor in a way that resists relative rotation and operates directly on the rotor shaft, which is preferably made of metal. Alternatively, the motor rotor may, for example, be supported on the rotor shaft by rolling bearings. The rotor shaft is indirectly or directly, force-fitted, supported in the spacer by a tapered seat connection; that is, the rotor shaft is fixed in a corresponding rotor shaft housing by a frictional engagement connection. The rotor shaft housing may, for example, be a separate bearing sleeve connected to the spacer.

[0011] Preferably, the rotor shaft housing is designed to be integrated with the spacer tank, i.e., the rotor shaft housing is integrated into the spacer tank, thereby eliminating the additional installation steps of connecting a separate bearing sleeve to the spacer tank. This makes the installation process of the electric motor vehicle fluid pump particularly simple and cost-effective, allowing the total cost of the electric motor vehicle fluid pump to be significantly reduced compared to pumps known according to the prior art.

[0012] In a preferred embodiment of the invention, the spacer tank has a conical rotor shaft receiving portion. Further, at least one end section, i.e., a section on one of the two axial ends of the rotor shaft, is designed to be conical, such that the cone of the rotor shaft substantially corresponds in its basic dimensions, such as length, diameter, and angle, to the cone in the rotor shaft receiving portion. This allows the rotor shaft to be axially and rotatably locked in the rotor shaft receiving portion by pressing the conical end section of the rotor shaft into the conical rotor shaft receiving portion, forming a conical seat connection or a conical press-fit connection. This force engagement ensures the rotor shaft is supported against relative rotation within the rotor shaft receiving portion.

[0013] The spacer tank is preferably designed as a deep-drawn sheet metal part. This makes it possible to manufacture the spacer tank relatively simply and at low cost. Particularly preferably, the rotor shaft receiving portion is designed as a deep-drawn annular flange, which preferably extends axially from the bottom of the spacer tank toward the interior of the spacer tank. The flange is formed such that a tapered inner wall is created, which gradually tapers toward the bottom of the spacer tank. In general, the rotor shaft receiving portion can only be manufactured by deep drawing through its taper, because in principle, at least a small draft angle is required in order to remove the deep-drawing punch again after the deep-drawing process. Therefore, by applying the deep-drawing process, the rotor shaft receiving portion can be manufactured relatively simply in a single working step, and due to sufficient precision for the tapered seat connection, the rotor shaft receiving portion allows direct reception of the tapered end section of the rotor shaft. The taper of the mating surfaces allows for a coarser specification of the tolerances of the rotor shaft receiving portion and the rotor shaft in terms of their manufacturing tolerances. Unlike cylindrical press-fit connections, tapered press-fit connections compensate for tolerance-dependent dimensional differences, particularly diameter differences, between two parts to be joined relatively easily by correspondingly and progressively shrinking the cone until it is compressed. As a result, significantly less waste is generated during manufacturing 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 in the same manner as the first end section of the rotor shaft. This allows for a simpler installation method for the electric vehicle fluid pump, as it is not necessary to orient the prefabricated shaft accordingly before installation, but rather it can be pressed into the rotor shaft housing at any axial end.

[0015] In a particularly preferred embodiment of the invention, the taper angle of the tapered press-fit connection is less than 10°, wherein this taper angle is definitively defined by the taper angle of the rotor shaft end section. Particularly preferably, the taper angle is between 3° and 7°, thereby allowing for relatively easy engagement of the rotor shaft and the rotor shaft housing, while generating a high force fit between the mating surfaces, ensuring that the rotor shaft is particularly stable within the rotor shaft housing.

[0016] In an advantageous design of the invention, the bottom of the rotor shaft housing does not extend axially beyond the bottom of the spacer tank in the direction outside the spacer tank. Since the bottom of the spacer tank is typically used to cool power electronic components for controlling the motor, large-area contact between the bottom of the spacer tank and the printed circuit board carrying the power electronics is preferred. Therefore, the rotor shaft housing should not extend beyond a reference plane of the bottom of the spacer tank in the direction of the printed circuit board, wherein this reference plane is formed by the end face of the spacer tank surrounding the rotor shaft housing.

[0017] The tapered press-fit connection between the rotor shaft and the spacer tank enables the use of a deep-drawn spacer tank, which includes a deep-drawn rotor shaft housing integrated into the spacer tank, directly accommodating the rotor shaft. This allows for the particularly cost-effective manufacture and simple installation of the electric motor vehicle fluid pump according to the invention. Attached Figure Description

[0018] In the following, a preferred embodiment of the electric fluid pump for motor vehicles according to the present invention is described in detail with reference to the accompanying drawings. In the drawings:

[0019] Figure 1 A schematic diagram of an electric motor vehicle fluid pump according to the invention is shown in a longitudinal section along the rotor shaft, and...

[0020] Figure 2 It shows Figure 1 An enlarged detail view of the conical seat connection of the electric motor vehicle fluid pump shown. Detailed Implementation

[0021] Figure 1 An electric circulating water pump 10 for supplying auxiliary cooling circulation to a motor vehicle is shown. The circulating water pump 10 includes a two-piece pump housing 12 comprising a canister-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 sleeve 17. Further, the circulating water pump 10 includes a pump rotor 16 with a pump impeller 161, wherein the pump impeller is rotatably arranged within the pump chamber 15 and operates on a centrifugal principle. The circulating water pump 10 also includes an electronically rectified electric motor 30 that drives the pump rotor 16. The electric motor 30 includes a built-in, rotatable motor rotor 32, which is electromagnetically driven by a motor stator 34 circumferentially surrounding the motor rotor 32. A deep-drawn spacer 22 made of austenitic steel plate is arranged in the elongated annular gap between the motor rotor 32 and the motor stator 34, which fluidly separates the motor rotor 32 from the motor stator 34 and thereby forms a wet chamber on the rotor side and a dry chamber on the stator side within the pump housing 12.

[0022] In addition to the motor stator 34, a printed circuit board 40 is arranged in the dry chamber, which is equipped with power electronic components for controlling the motor 30. The printed circuit board 40 is arranged in parallel in an adjacent manner, that is, in a manner that makes large-area heat transfer contact with the bottom 222 of the spacer tank, so that the water circulating in the wet chamber carries away the heat generated by the power electronic components and transferred to the bottom 222 of the spacer tank.

[0023] The spacer includes a tapered rotor shaft receiving portion 221, which is formed by a deep-drawn annular flange 223 integrated into the spacer 22 and extending into the spacer interior 224. A metal rotor shaft 14 is press-fitted into the rotor shaft receiving portion 221, having tapered end sections 141 and 142 at its two axial ends, which substantially correspond to the cone in the rotor shaft receiving portion 221 in terms of its 5° cone angle α, its base diameter d, and its cone length L corresponding to at least 1.5 times the base diameter d. The first tapered end section 141 is pressed into the tapered rotor shaft receiving portion 221 to form a tapered seat connection portion 20 (see also...). Figure 2 The rotor shaft 14 is forcefully supported in the spacer tank 22, so that the rotor shaft 14 is axially fixed and locked to prevent torsion. The rotor shaft receiving part 221 extends non-axially beyond the bottom 222 of the spacer tank in the direction of the printed circuit board 40, so that the printed circuit board 40 can be placed relatively close to the bottom 222 of the spacer tank, thereby allowing a relatively large contact area between the printed circuit board 40 and the bottom 222 of the spacer tank, which ensures good heat dissipation.

[0024] Pump rotor 16 and motor rotor 32 are interconnected in a manner resistant to relative rotation, wherein motor rotor 32 is indirectly supported on rotor shaft 14 via plastic sliding bearing sleeve 162 of pump rotor 16. Additionally, pump rotor 16 is axially locked at its axial end on the pump impeller side by an axially acting sliding bearing ring 45 located in pump cover plate 122. Motor rotor 32, driven by motor stator 34, in turn drives pump rotor 16 together with pump impeller 161, thereby drawing water axially into pump impeller 161 through inlet channel 11 extending in suction sleeve 17, and spraying it radially towards vortex disk 151 of pump chamber 15 due to centrifugal force.

[0025] The tapered crimp connection 20 provides a relatively secure and easy-to-install connection between the rotor shaft 14 and the spacer tank 22. Additionally, the tapered crimp connection 20 allows the rotor shaft receiving portion 221 to be designed as a deep-drawn flange 223 integral with the deep-drawn spacer tank 22, thereby resulting in a relatively low production cost for the circulating water pump 10 according to the invention.

Claims

1. An electric motor vehicle fluid pump (10), comprising: A fixed spacer (22) fluidly separates the motor rotor (32) and motor stator (34) of the motor (30) driving the pump rotor (16) from each other. A fixed rotor shaft (14) on which the motor rotor (32) driving the pump rotor (16) is rotatably supported. The rotor shaft (14) has at least one tapered end section and is supported in the spacer (22) indirectly or directly by means of a tapered press-fit connection (20).

2. The electric motor vehicle fluid pump (10) according to claim 1, wherein the spacer tank (22) has a tapered rotor shaft housing (221), and at least one of the rotor shafts (14) pressed into the tapered end section of the rotor shaft housing (221) is designed in a corresponding manner such that the rotor shaft (14) is supported in the rotor shaft housing (221) against relative rotation.

3. The electric motor vehicle fluid pump (10) according to claim 1 or 2, wherein the spacer tank (22) is designed as a deep-drawn sheet metal component.

4. The electric motor vehicle fluid pump (10) according to claim 3, wherein the rotor shaft housing (221) is designed to be integral with the spacer tank (22).

5. The electric motor vehicle fluid pump (10) according to claim 4, wherein the rotor shaft housing (221) is designed as a deep-drawn flange (223) that axially protrudes toward the interior (224) of the spacer tank (22) with reference to the bottom (222) of the spacer tank (22).

6. The electric motor vehicle fluid pump (10) according to claim 5, wherein the second end section (142) of the rotor shaft (14) is designed in the same manner as the first end section (141) of the rotor shaft (14).

7. The electric motor vehicle fluid pump (10) according to claim 5, wherein the cone angle (a) of the tapered crimp connection (20) is less than 10°.

8. The electric motor vehicle fluid pump (10) according to claim 5, wherein the bottom (226) of the rotor shaft housing (221) extends non-axially beyond the bottom (222) of the spacer tank in the direction of the spacer tank exterior (225).

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