Motor housing cover assembly of a pump with components surrounded by molding compound

Abstract

Motor housing cover arrangement (21) comprising a motor housing cover (1) of an electric motor of a pump having a top side (3) and a bottom side (4) and a printed circuit board (5) populated with electronic components, wherein the motor housing cover (1) is penetrated by electrical contacts, each of which makes electrical contact with the printed circuit board (5) by a first end region and is arranged with a second end region in an electrical plug connector (2) that is arranged on the top side (3) of the motor housing cover (1), characterized in that the motor housing cover (1), the populated printed circuit board (5) and the plug connector (2) are at least partially surrounded by molding compound (9) in a molding process, wherein the molding compound (9) fastens the printed circuit board (5) and the plug connector (2) to the motor housing cover (1).

Description

[0001] The present invention relates to a motor housing cover assembly having the features of the preamble of claim 1, a pump and a method for producing a pump having the features of the preamble of claim 13.

[0002] Pumps often have DC motors. DC motors comprise a rotor connected to a motor shaft and mounted for rotation in a housing. The rotor is equipped with permanent magnets. A stator carries a number of windings on an iron core. With appropriate control, the windings generate a magnetic field that drives the rotor to rotate. The windings are usually wound in three-phase and are accordingly provided with three electrical connections via which the windings can be connected to a control unit (ECU). For low power ratings, busbars in the form of conductor foils can be used. For higher power ratings, the winding connecting wires are contacted via copper sheet busbars, which are combined in a busbar unit. The busbar unit is located above the stator and covers most of the upper surface.The circuit board is contacted using contact plugs or by processes such as soldering or welding. The circuit board, in turn, is located above the busbar unit and below a motor housing cover that closes off the motor housing. The electronics arranged on the circuit board heats up during operation. The heat is dissipated via the motor housing cover and a thermally conductive material arranged between them. A control unit placed on the circuit board can be controlled via a connector that is screwed onto the top of the motor housing cover and has electrical contacts that run through the motor housing cover to the circuit board. The populated circuit board is also screwed to the motor housing cover. The screw connections require additional components and assembly steps.

[0003] Patent EP 3 245 712 B1 discloses an automotive auxiliary unit used, for example, as a pump in a vehicle. A circuit board is located in a potting body within the engine housing. The housing body or cover seals the interior of the engine. The circuit board is inserted into the housing opening.

[0004] Patent DE 10 2018 200 645 B3 discloses a fluid machine with a housing body that includes a molded printed circuit board with a diagnostic port. A plastic material surrounds the circuit board and forms the housing body. The circuit board is located inside the housing body, and the housing body has a diagnostic port with a diagnostic area, which can be purchased together with a diagnostic connector as a connector.

[0005] German Patent Application DE 10 2016 101 963 A1 describes an electric motor for a fluid pump, in particular an oil pump. A cover seals off a receiving chamber containing a circuit board. The electronics are connected to the connector using several overmolding processes and encased in molding compound.

[0006] The published patent application DE 10 2018 214 228 A1 describes electronics for an electric motor in a motor vehicle. The electronics are located in the motor of the vehicle.

[0007] The invention is based on the object of providing a cost-effective, simple, stable and thermally efficient solution for a connection between a busbar unit, a printed circuit board and a motor housing cover.

[0008] This object is achieved by a motor housing cover assembly having the features of claim 1, a pump and a method for producing a pump having the features of claim 13.

[0009] Accordingly, a motor housing cover assembly is provided comprising a motor housing cover of an electric motor having a top side and a bottom side, and a printed circuit board populated with electronic components. The motor housing cover is penetrated by electrical contacts, each of which makes electrical contact with the printed circuit board by a first end region and is arranged with a second end region in an electrical plug connector arranged on the top side of the motor housing cover. The motor housing cover, the populated printed circuit board, and the plug connector are at least partially surrounded by molding compound in a molding process, the molding compound fastening the printed circuit board and the plug connector to the motor housing cover. Screwing the components together is therefore not necessary. The molding compound also improves heat dissipation away from the electronics. Compared to conventional electric motors, components and assembly steps can be eliminated.

[0010] The molding process is preferably transfer molding. The molding compound is preferably a thermoset or a bulk molding compound (BMC).

[0011] It is advantageous if the molding compound completely covers the top and bottom of the engine housing cover, and if an edge area of ​​the engine housing cover (at least on the bottom) is free of molding compound. This free edge area can be used for attachment to an engine housing.

[0012] Preferably, the molding compound completely encloses the populated circuit board, which makes heat conduction particularly efficient.

[0013] The circuit board is preferably interspersed with contact plugs, each of which makes electrical contact with the circuit board at one end and has a contact area protruding from the molding compound at the other end. The contact area can be designed as a press-fit contact. Electrical contact with the circuit board can be established via an SMD (surface-mounted component) pad (landing area).

[0014] It is advantageous to place spacers between the motor housing cover and the circuit board. These can be formed on the motor housing cover or the circuit board. The spacers ensure a uniform thickness of the molding compound between the components.

[0015] Preferably, capacitors are arranged on the circuit board, with a clearance formed between the molding compound and the capacitors in case the capacitors outgas. The clearance can be formed by a cover or the mold used in the molding process.

[0016] It is conceivable for the circuit board to be populated on one or both sides. Preferably, at least one capacitor is located on the side of the circuit board closest to the motor housing cover. It is advantageous if this capacitor extends through the motor housing cover, thus saving installation space.

[0017] At least two guide pins extending in the longitudinal direction can be arranged on the underside of the circuit board, which are designed for positioning and centering during assembly of the electric motor.

[0018] Furthermore, a pump comprising an electric motor with - a rotor which is mounted so that it can rotate around an axis of rotation, - a stator, wherein the stator has a stator core and coils wound on the stator core, and wherein the windings are formed from at least one winding wire with winding wire ends, - a busbar unit arranged on top of the stator, which has busbars that are in contact with the coils, - a circuit board, and with - a motor housing which surrounds the rotor, the stator, the busbar unit and the printed circuit board and which has a mounting opening which is closed by a motor housing cover, wherein the motor housing cover and the printed circuit board are part of the previously described motor housing cover assembly.

[0019] It is advantageous if the contact area of ​​the contact plug establishes an electrical contact with the stator, in particular the busbar unit of the electric motor.

[0020] The previously described guide pins, which are connected to the circuit board or can also be connected to the busbar unit, engage with the other component to position and center the components.

[0021] Furthermore, a method for producing a pump described above is provided, the method comprising the following steps: a) Positioning the assembled circuit board on the underside of the motor housing cover, b) Positioning a connector on the top of the motor housing cover, whereby the connector surrounds electrical contacts that penetrate the motor housing cover and electrically contact the circuit board with one end area, c) Placing a mold around the assembly of circuit board, connector and motor housing cover and d) Introducing (in particular injection molding) molding compound into the mold so that the motor housing cover, the populated circuit board and the connector are at least partially surrounded by the molding compound, wherein the molding compound fixes the circuit board and the connector to the motor housing cover.

[0022] This process offers the advantages mentioned above. The molding process can be injection molding, conventional casting, vacuum casting, or transfer molding.

[0023] Preferably, in a process step prior to step a), contact plugs are inserted from top to bottom through the circuit board. The contact plugs have an SMD pad at one end, which is located on the top side, and a contact area at the other end, which is located below the circuit board. The contact area is not surrounded by the molding compound in step d). As already described, the contact area can be designed as a press-fit contact.

[0024] Preferably, the motor housing cover assembly produced in step d) is contacted with a stator assembly comprising a stator and busbar unit, wherein guide pins are arranged on the underside of the motor housing cover assembly or on the top side of the stator assembly and bores for receiving the guide pins are arranged on the respective other component, and the method comprises the following steps: - Aligning the motor housing cover assembly and the stator assembly, - engagement of the guide pins in the holes, and - Contacting the contact areas of the contact plugs with the busbar unit.

[0025] The guide pins thus center and position the components in order to determine the position of the components relative to one another and to ensure contact between the contact plugs and the busbar unit, even in the case of blind assembly.

[0026] Preferred embodiments of the invention are explained in more detail below with reference to the drawings. Similar or equivalent components are designated by the same reference numerals in the figures. They show: Fig. 1: a spatial view of a motor housing cover assembly with connector, motor housing cover and circuit board, Fig. 2: a longitudinal section through the arrangement of the Fig. 1 with engine housing wall, Fig. 3: a detailed view of a contact plug passing through the circuit board, Fig. 4: a longitudinal section through another engine housing cover arrangement, Fig. 5: a detailed view of a circuit board arranged on the engine housing cover, Fig. 6: a spatial representation of an assembly of a stator assembly on the motor housing cover assembly of the Fig. 1, Fig. 7: a plan view of a motor housing cover of a motor housing cover assembly, Fig. 8: a spatial representation of an assembly of a stator arrangement on the motor housing cover arrangement of a second embodiment, and Fig. 9: a spatial representation of an assembly of a stator arrangement on the motor housing cover arrangement of a further embodiment.

[0027] Fig. 1 shows a motor housing cover 1 of an electric pump, in particular a coolant pump used in motor vehicles. Such electric pumps have an electric motor that is seated in a motor housing and drives an impeller. On the side opposite the impeller, the motor housing has a mounting opening that is closed by the motor housing cover. The motor housing cover 1 is penetrated by electrical contacts that are arranged in an electrical connector 2 that is connected to the motor housing cover 3 on the top side thereof. The connector 2 can be contacted with a plug for controlling the electric motor. On the side remote from the connector, the underside of the motor housing cover 4, there is a printed circuit board 5 that is equipped with components of a control unit 6.The printed circuit board 5 is interspersed with contact plugs 7, which in the example shown each form a press-fit contact 8 on the underside and can establish an electrical contact with the stator of the electric motor.

[0028] The motor housing cover 1, as well as the populated circuit board 5 and the connector 2, are enclosed in molding compound 9 in a molding process. A motor housing cover assembly is formed in the molding process. The molding process is preferably transfer molding, also known as injection molding. For this purpose, a mold is placed around the components, and the molding compound is introduced using transfer molding. Since low temperatures and low pressures are used in transfer molding, the control unit is not damaged. The molding compound 9 is preferably a thermoset or bulk molding compound.

[0029] The molding compound 9 completely surrounds the motor housing cover 1 on the top and bottom surfaces 3, 4. An edge region of the plate-shaped motor housing cover 10 is free of molding compound to enable attachment to the motor housing. The connection between the motor housing cover 1 and the motor housing (not shown) is preferably made by a material bond, without a seal or screw connection. Friction stir welding, preferably in the axial direction, flanging, or laser welding can be used for the connection. If a surface other than the edge region is used for the connection, this surface is kept free of molding compound. The molding compound 9 completely encloses the circuit board 5 and thus also all components of the control unit 6. Only the press-fit contacts of the contact plugs 8 protrude from the molding compound 9. The sealing during the molding process is preferably carried out in the tool itself and / or by geometries on the contact plug 7 and / or the connector 2.

[0030] The connector 2 is surrounded by the molding compound 9 only in a base area 11, whereby the connector 2 is firmly connected to the motor housing cover 1. Additional screwing or gluing is therefore unnecessary.

[0031] Fig. Figure 2 shows in detail the components surrounded by the molding compound 9. When the motor housing cover 1 is mounted on one end face of the motor housing 12, the molding compound 9 protrudes into the motor housing 13 and can be flush with it on the inside, as shown. However, it is also conceivable that a gap is formed between the molding compound 9 and the housing wall of the motor housing 13.

[0032] Capacitors 14 are arranged on the circuit board 5, which are covered with a protective cap before the molding process or the mold is adapted during the molding process so that the molding compound encloses the capacitors 14, but is spaced from them by a gap or space that enables outgassing of the components 14.

[0033] The molding compound 9 efficiently dissipates the heat generated by the control unit to the outside via the motor housing cover 1. The metal motor housing cover 1 serves as a heat sink. Furthermore, the molding compound 9 fixes both the assembled circuit board 5 and the connector 2 to the motor housing cover 1.

[0034] The contact plugs 7 are inserted during assembly when assembling the printed circuit board 5. They have the press-fit contact 8 on one side and an SMD pad 15 on the other side, which consists of only one soldering surface and creates an electrical and mechanical connection between the top side of the printed circuit board 5 and the contact plug 7 (see also Fig. 3).

[0035] With the help of the SMD pad 15, centering can be achieved through the cylindrical hole diameter and fixation to the circuit board 5 by soldering. The SMD pads 15 are also enclosed by the molding compound 9, which minimizes the risk of deformation during contact with the stator, especially with the busbar unit. By surrounding the circuit board with molding compound, the SMD pad 15 also supports itself against the molding compound, so that the insertion forces do not stress the soldering point.

[0036] Instead of a press-fit contact 8, it is also conceivable to form a crimp sleeve for a crimp connection, an insulation displacement contact, a plug contact or welded contacts on the contact plug 7 for connection to the stator, in particular the busbar unit.

[0037] Fig. Figure 4 shows a further embodiment in which a capacitor 14 is additionally arranged on the top side of the circuit board 5, which extends through the motor housing cover 1. As in the previous example, with a circuit board 5 populated on both sides, it is ensured here too that the electronic components are completely surrounded by the molding compound 9. The capacitor 14 arranged above the circuit board also has a free space towards the molding compound 9, allowing the capacitor 14 to outgas.

[0038] Fig. 5 shows in detail the arrangement of the printed circuit board 5 below the motor housing cover 1. In order to ensure a distance between the motor housing cover 1 and the printed circuit board 5, in the illustrated embodiment, plastic spacers 16 are attached or molded onto the top side of the printed circuit board 5. It is also conceivable to mold or attach the spacers 16 onto the underside of the motor housing cover 4. The spacers 16 allow the molding compound (not shown) to enclose the top side of the printed circuit board and the underside of the motor housing cover, so that there are no areas free of molding compound and heat dissipation is particularly optimal because no air is trapped between the components and the molding compound is evenly distributed between the components.

[0039] The Fig. 6, Fig. 8 and Fig. 9 shows three different embodiments with guide pins 17, which serve to center and position the motor housing cover assembly 18 on the top side of the stator assembly 19, wherein the stator assembly 19 consists of the stator 20 and the busbar unit arranged on the front side. The guide pins 17 are arranged on one of the two components and engage with the other component to determine the relative position of the components and to ensure contact between the contact plugs 7 and the busbar unit during blind assembly.

[0040] In Fig. 6, the guide pins 17 are formed on the busbar unit. They are perpendicular to the top side of the busbar unit and engage in bores in the motor housing cover assembly 21 from the bottom side. The bores 21 preferably do not extend completely through the motor housing cover assembly 21 (blind hole), so that the motor compartment enclosed by the motor housing is sealed. The area of ​​the bore in the motor housing cover 1 and the circuit board 5 is closed by the molding compound 9 during the molding process. On the top side, as can be seen from Fig. 7, the closed hole in the molding compound 9 can be seen.

[0041] In the variant of the Fig. 8, the guide pins 17 are formed on the underside of the motor housing cover 4 and are perpendicular to the underside 4. They penetrate the printed circuit board 5 and protrude on the underside above the molding compound 9. However, it can also be provided that the guide pins 17 only penetrate the printed circuit board 5 or that the guide pins 17 are molded onto the underside of the motor housing cover 4 during the molding process. The guide pins 17 protrude beyond the contact plugs 7 so that during assembly they are the first to insert into the busbar unit of the stator arrangement and carry out pre-centering. It can also be provided that the guide pins 17 are less tall than the contact plugs 7. In this case, the counter-form provided for the guide pins 17 on the busbar unit must protrude to ensure that the guide pins 17 are the first to insert into the counter-form before the contact plugs 7 are contacted.During the molding process, the holes in the printed circuit board through which the guide pins 17 protrude are sealed, unless the guide pins 17 themselves are formed during the molding process. The guide pins 17 engage in corresponding holes 22 on the top side of the busbar unit.

[0042] It can additionally be provided that the connector 2 has a guide pin 23 on the underside, which penetrates the motor housing cover 1 and the printed circuit board 5 and protrudes from the molding compound 9 on the underside, as in Fig. 9. This additional guide pin 23 also engages the stator assembly 19 for positioning the motor housing cover assembly 18 on the busbar unit.

[0043] The guide pins 17 generally allow the tolerance chain for positioning the motor housing cover assembly 18 on the stator assembly 19 to be reduced. The guide pins 17 can have a contact shoulder as an axial stop.

[0044] For positioning, a contact shoulder can additionally be formed on the contact plugs 7 as an axial stop or a sleeve surrounding the contact plug 7 can be provided as a contact shoulder.

Claims

[1] Motor housing cover arrangement (21) comprising a motor housing cover (1) of an electric motor of a pump with a top side (3) and a bottom side (4) and a circuit board (5) equipped with electronic components, wherein the motor housing cover (1) is penetrated by electrical contacts, each of which makes electrical contact with the circuit board (5) with a first end region and is arranged with a second end region in an electrical plug connector (2) which is arranged on the top side (3) of the motor housing cover (1), characterized by that the motor housing cover (1), the populated printed circuit board (5) and the connector (2) are at least partially surrounded by molding compound (9) in a molding process, wherein the molding compound (9) fastens the printed circuit board (5) and the connector (2) to the motor housing cover (1). [2] Engine housing cover assembly according to claim 1, characterized by that the molding compound (9) is a thermoset or a bulk molding compound. [3] Engine housing cover arrangement according to claim 1 or 2, characterized by that the molding compound (9) completely surrounds the engine housing cover (1) on the top and bottom sides (3,4) and an edge area of ​​the engine housing cover (10) is free of molding compound. [4] Engine housing cover arrangement according to one of the preceding claims, characterized by that the molding compound (9) completely encloses the populated circuit board (5). [5] Engine housing cover arrangement according to one of the preceding claims, characterized by that the printed circuit board (5) is penetrated by contact plugs (7), each of which makes electrical contact with the printed circuit board (5) at one end and has a contact area (8) at the other end which protrudes from the molding compound (9). [6] Engine housing cover arrangement according to one of the preceding claims, characterized by that spacers (16) are arranged between the motor housing cover (1) and the circuit board (5). [7] Engine housing cover arrangement according to one of the preceding claims, characterized by that capacitors (14) are arranged on the circuit board (5), wherein a free space is formed between the molding compound (9) and the capacitors (14). [8] Engine housing cover arrangement according to claim 7, characterized by that at least one capacitor (14) is arranged on the side of the circuit board (5) near the motor housing cover and this passes through the motor housing cover (1). [9] Engine housing cover arrangement according to one of the preceding claims, characterized by that at least two guide pins (17) extending in the longitudinal direction are arranged on the underside of the printed circuit board (5). [10] Pump comprising an electric motor with - a rotor which is mounted so that it can rotate around an axis of rotation, - a stator (20), wherein the stator (20) has a stator core and coils wound on the stator core, and wherein the windings are formed from at least one winding wire with winding wire ends, - a busbar unit arranged on top of the stator, which has busbars that are in contact with the coils, - a printed circuit board (5), and with - a motor housing (13) which surrounds the rotor, the stator (20), the busbar unit and the circuit board (5) and which has a mounting opening which is closed by a motor housing cover (1), characterized by that the motor housing cover (1) and the circuit board (5) are part of the motor housing cover arrangement (21) according to one of the preceding claims. [11] Pump according to claim 10, characterized by that the contact area of ​​the contact plugs (8) establishes an electrical contact with the stator of the electric motor (20). [12] Pump according to claim 10 or 11, characterized by that the pump comprises guide pins (17) which are connected to the circuit board (5) or to the busbar unit and which engage in the other component for positioning and centering the components. [13] Method for producing a pump with an electric motor with - a rotor which is mounted so that it can rotate around an axis of rotation, - a stator (20), wherein the stator (20) has a stator core and coils wound on the stator core, and wherein the windings are formed from at least one winding wire with winding wire ends, - a busbar unit arranged on top of the stator, which has busbars that are in contact with the coils, - a populated printed circuit board (5), and with - a motor housing (13) which surrounds the rotor, the stator (20), the busbar unit and the circuit board (5) and a motor housing cover (1) which is designed to close a mounting opening of the motor housing (13), characterized by that the procedure includes the following steps: a) Positioning the assembled circuit board (5) on the underside of the motor housing cover (4), b) positioning a connector (2) on the top side (3) of the motor housing cover (1), the connector (2) surrounding electrical contacts which pass through the motor housing cover (1) and make electrical contact with the printed circuit board (5) with an end region, c) Place a mold around the assembly of circuit board (5), connector (2) and motor housing cover (1) d) introducing molding compound (9) into the mold so that the motor housing cover (1), the populated circuit board (5) and the connector (2) are at least partially surrounded by the molding compound (9), wherein the molding compound (9) fastens the circuit board (5) and the connector (2) to the motor housing cover (1). [14] Method according to claim 13, characterized by in that in a method step before step a) contact plugs (7) are inserted from top to bottom through the printed circuit board (5), wherein the contact plugs (7) have an SMD pad (15) at one end, which is located on the top side, and a contact area (8) at their other end, which is located below the printed circuit board (5), and the contact area is not surrounded by the molding compound in step d). [15] Method according to claim 14, characterized bythat the motor housing cover arrangement (21) produced in step d) is contacted with a stator arrangement (19) consisting of a stator (20) and a busbar unit, wherein guide pins (17) are arranged on the underside of the motor housing cover arrangement (21) or on the top side of the stator arrangement (19) and bores (22) for receiving the guide pins (17) are arranged on the respective other component, and the method comprises the following steps: - Bringing the motor housing cover assembly (21) and the stator assembly (19) towards each other, - engagement of the guide pins (17) in the holes (22), and - Contacting the contact areas of the contact plugs (8) with the busbar unit.

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