Automotive electronic fluid pump

The invention refers to an automotive electronic fluid pump with an electronically commutated pump motor driving a pump rotor being provided in a wet motor rotor chamber which is separated from a dry motor stator chamber by a substantially cylindrical separation tube. This pump concept avoids any dynamic sealings between the wet part and the dry part of the fluid pump.

An important issue of this pump concept is the exact coaxiality of the motor stator, the separation tube and the motor rotor. A high reproduction quality of the coaxiality allows to define a small airgap between the motor stator and the motor rotor, and a small airgap provides a high electromagnetic efficiency of the motor. Another important issue of any electrical automotive device is the electromagnetic compatibility (EMC) of that device.

Generally, a metal motor frame provides a high reproduction quality. WO 2017 140 334 Al discloses a typical motor concept wherein a deep-drawn metal sheet body defines the separation tube, a rotor slide bearing ring and a transversal separation wall for fluidically separating the wet motor rotor chamber from the dry electronics chamber. The pump housing is completely made of plastic so that no electromagnetic shielding of the motor stator is provided. The electromagnetic shielding could be provided by a metal pump housing which would result in a relatively heavy and expensive fluid pump both of which is generally not acceptable for automotive devices and applications. It is an object of the invention to provide a competitive automotive electronic fluid pump with good electromagnetic efficiency and electromagnetic compatibility.

This object is solved with an automotive electronic fluid pump with the features of claim 1.

The automotive electronic fluid pump according to the invention is provided with an electric pump motor comprising an electronic motor stator with several stator coils. The rotor comprises a motor rotor, a pump rotor and a rotor shaft mechanically and co-rotatably connecting the motor rotor and the pump rotor. The motor rotor is preferably permanently magnetized and is electromagnetically driven by the motor stator surrounding the central motor rotor. The pump rotor can be a positive displacement pump rotor or is, preferably, a flow pump rotor.

The motor electronics comprises a commutation electronics and several power semiconductors for electrically energizing the stator coils. The motor electronics is arranged within a dry electronics chamber axially adjacent to a wet motor rotor chamber. A non-ferrimagnetic separation tube flu id ically separates the wet motor rotor chamber from the dry motor stator chamber and is provided in the cylindrical airgap between the motor rotor and the rotor stator. A substantially transversal separation wall flu id ically separates the wet motor rotor chamber from the dry electronics chamber.

According to the invention, a pot-like motor housing frame is provided, the motor housing frame defining a bottom wall substantially lying in a transversal plane and a cylindrical side wall being substantially cylindrical in shape. The housing frame bottom wall defines the separation wall between the wet motor rotor chamber and the dry electronics chamber. The motor housing frame side wall portion supports the radial outside of the motor stator.

The motor housing frame is made of a deep-drawn metal sheet body also defining a cylindrical support collar axially proximally protruding from the frame bottom wall into the motor rotor chamber and being made by reverse-drawing. No additional machining is necessary to provide a sufficiently precise cylindrical support collar. The cylindrical support collar directly supports a cylindrical support section of the separation tube. The separation tube can be made of any suitable non-ferromagnetic material, and preferably is made of plastic.

Preferably, the motor housing frame is made of a ferromagnetic metal material to provide a good electromagnetic shielding of the motor stator resulting in a good electromagnetic compatibility EMC of the fluid pump. Preferably, the motor housing frame is electrically grounded. Since the metal motor housing frame also defines the transversal separation wall between the wet motor rotor chamber and the dry electronics chamber, the transversal separation wall has a relatively high thermal conductivity so that the heat generated by the motor electronics can efficiently be conducted via the transversal separation wall to the pumping fluid. Preferably, the power semiconductors of the motor electronics are thermally coupled to the motor housing frame without any airgap in between.

The pumping fluid generally can be a gas or a liquid, but preferably is a liquid. Preferably, the fluid pump therefore is a liquid pump, and more preferably is a coolant liquid pump of an automotive coolant and/or a heating circuit. The metal sheet motor housing frame is sufficiently solid and stiff to precisely support and coaxiality position the motor stator and the separation tube. Additionally, the motor housing frame electromagnetically shields the motor stator so that a good electromagnetic compatibility EMC is realized. The separation tube preferably is made of a light-weight and non-ferromagnetic material, for example is made of a very cost-effective plastic material.

Preferably, the support collar of the motor housing frame supports the radial outside surface of the support section of the separation tube. Preferably, the support collar approximately lies in the cylinder plane defined by the cylindrical airgap between the motor rotor and the motor stator. This results in a relatively large motor stator chamber which is not radially inwardly constricted in the section defined by the support collar. Preferably, the separation tube support section has a reduced radius compared to an air gap section of the separation tube.

Preferably, the plastic separation tube body also defines a rotor shaft bearing support for rotatably supporting the rotor shaft. Preferably, the rotor shaft bearing is of the slide-bearing-type, and the plastic separation tube body directly supports or even directly defines the outside bearing ring of the slide bearing.

Preferably, the complete proximal transversal wall of the electronics chamber is defined by the transversal bottom wall of the pot-like motor housing frame. The proximal transversal wall of the electronics chamber is the wall which separates the electronics chamber from the motor rotor chamber as well as from the motor stator chamber. Since the complete proximal transversal wall of the electronics chamber is defined by the transversal bottom wall of the motor housing frame, no additional wall for separating the electronics chamber from the motor stator chamber is necessary.

Preferably, a separate and additional plastic motor housing houses and surrounds the motor housing frame. The plastic motor housing completely radially surrounds the motor housing frame so that the motor housing provides a mechanical protection of the motor housing frame. The motor stator therefore is radially surrounded by an inner wall defined by the motor housing frame and an adjacent outer wall defined by the plastic motor housing. Preferably, the plastic motor housing defines the circumferential side wall of the electronics chamber.

One embodiment of the invention is explained with reference to the enclosed drawings, wherein figure 1 shows schematically a longitudinal section of an automotive electronic fluid pump with a motor housing frame and a separation tube supported by the motor housing frame, and figure 2 only the motor housing frame and the separation tube of figure 1 in a longitudinal section.

Figure 1 shows an automotive electronic fluid pump 10 which is, in the present embodiment, a liquid pump for pumping a coolant liquid in an automotive coolant circuit. The automotive electronic fluid pump 10 is provided with a brushless electric pump motor 14 which is commutated and energized by a motor electronics 42 comprising a commutation electronics and several power semiconductors 44 for energizing several stator coils 52 of an outside motor stator 50. The pump 10 is designed dynamic-sealing-free and comprises a wet motor rotor chamber 62 comprising a wet motor rotor 54 and comprises a ringlike dry motor stator chamber 61 with a dry motor stator 50, both chambers 61, 62 being fluidically separated from each other by a substantially cylindrical plastic separation tube 70.

The motor rotor 54 is permanently magnetized and comprises a plurality of identical transversal ferromagnetic rotor sheets 55 and several permanently magnetized rotor pole magnets 56 defining several magnetic rotor poles. The motor rotor 54 is rotating around a longitudinal pump axis A. The rotor of the fluid pump 10 comprises the motor rotor 54, a rotor shaft 30 and a pump rotor 34. The pump rotor 34 is, in this embodiment, an impeller wheel with an axial pump rotor inlet opening 35 and a circumferential radial pump rotor outlet opening 36 so that the present fluid pump 10 is a flow pump. The rotor shaft 30 is provided with an axial coolant channel bore 31 and mechanically co-rotatably connects the motor rotor 54 with the pump rotor 34.

The pump rotor 34 is surrounded by a pump outlet volute 26 defined by a fluid housing part 20 defined by a plastic fluid housing part body 20' which also defines an axial pump inlet duct 28 and a tangential pump outlet duct (not shown in the drawings).

The motor stator 50 comprises a plurality of identical ferromagnetic transversal stator metal sheets 51 and the stator coils 52 which define several electromagnetic stator poles.

The pump motor 14 comprises a pot-like motor housing frame 80 made of a deep-drawn metal sheet body 80' of a ferromagnetic metal. The motor housing frame 80 defines a substantially cylindrical frame side wall 84 and a transversal frame bottom wall 82. The frame bottom wall 82 has two portions, which is the central bottom wall portion defining the transversal separation wall 64 for fluid ically separating the wet motor rotor chamber

62 from the dry electronics chamber 40, a ringlike ring bottom wall portion

63 radially surrounding the transversal separation wall 64. The motor housing frame 80 also defines a cylindrical axial support collar 66 protruding proximally axially from the transversal plane XZ of the frame bottom wall 82. The inside surface of the cylindrical support collar 66 directly supports a radial outside surface 702' of a support section 702 of the separation tube 70. The motor housing frame bottom wall 82 defines the complete proximal transversal wall 90 of the electronics chamber 40 separating the electronics chamber 40 from the motor rotor chamber 62 and the motor stator chamber 61.

The plastic separation tube 70 is made of a plastic separation tube body 70' and has a substantially cylindrical airgap section 701 and a substantially cylindrical support section 702 with an enforced support ring 72. The support section 702 substantially defined by the support ring 72 has a reduced radius compared to the airgap section 701, as shown in figure 2. The separation tube 70 also defines a ring -like rotor shaft bearing support 76 rotatably supporting the rotor shaft 30. The rotor shaft bearing support 76 is held by several radial support arms 74. The separation tube 70 is one integral part.

The pump housing is defined by the fluid housing part 20, a separate motor housing 22 completely housing the motor housing frame 80 and an electronics chamber lid 24. The motor housing 22 is defined by a plastic motor housing body 22' and the electronics chamber lid 24 is defined by a plastic lid body 24'.