Patent Publication Number: US-2018034181-A1

Title: Electric motor vehicle secondary assembly

Description:
CROSS REFERENCE TO PRIOR APPLICATIONS 
     This application is a U.S. National Phase application under 35 U.S.C. § 371 of International Application No. PCT/EP2015/050663, filed on Jan. 15, 2015. The International Application was published in German on Jul. 21, 2016 as WO 2016/112980 A1 under PCT Article 21(2). 
    
    
     FIELD 
     The present invention relates to an electric secondary assembly for motor vehicles, for example, to an electric water recirculation pump. 
     BACKGROUND 
     The term motor vehicle secondary assembly as used herein is intended to include all secondary assemblies that do not immediately serve to drive the motor vehicle, but are designed, for example, as a pump, an actuator, or as a mechanical switch. The respective working device can, for example, be driven by an electronically commutated drive motor since electronic commutation is free of wear and, in particular with pumps, allows a hermetic separation of the pump fluid from the commutation electronics if the drive motor is designed as a so-called canned motor. 
     The commutation electronics is generally substantially located on a motor control circuit board which may be equipped on one side or on two sides. Connecting lines lead from the motor control circuit board to a peripheral connector arrangement arranged on a housing body of the assembly housing. After assembly of the motor vehicle secondary assembly into the motor vehicle, a corresponding mating connector can be plugged into the connector arrangement so as to electrically connect the motor vehicle secondary assembly to a vehicle control. 
     The electrical motor vehicle secondary assembly is most often mounted in the axial direction, wherein, after assembly of the motor control circuit board in a transversal plane that is oriented approximately perpendicular to the rotational axis of the drive motor, the interior is finally closed with a housing body or cover. The housing body or cover comprises the connector arrangement that must be electrically connected to the motor control circuit board or is connected to the motor control circuit board only during assembly. A permanently good electric connection of the two exposed connector pins of the connector arrangement to the motor control circuit board is of utmost importance for a reliable operation of the motor vehicle secondary assembly. 
     SUMMARY 
     An aspect of the present invention is to provide an electric motor vehicle secondary assembly having electronic commutation which has a high electric reliability. 
     In an embodiment, the present invention provides an electric motor vehicle secondary assembly which includes a housing body comprising a housing opening, a drive motor configured to be electronically commutated, a working device configured to be driven by the drive motor, a peripheral connector arrangement comprising at least two exposed connector pins, a cast body comprising a connector core which is integrally molded thereon in one piece, and a motor control circuit board which is at least partly potted in the cast body. The connector core is configured to form a connector base. The at least two exposed connector pins are each formed by a respective single rigid pin element which is directly electrically connected to the motor control circuit board. The connector core of the cast body is configured to enclose each respective single rigid pin element between the motor control circuit board and the connector base. The connector core is plugged into the housing opening of the housing body so that the connector base completely closes the housing opening and the respective single pin elements project outward from the connector base through the housing opening. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention is described in greater detail below on the basis of embodiments and of the drawings in which: 
         FIG. 1  shows a longitudinal section of a motor vehicle secondary assembly according to the present invention including a motor control circuit board potted in a cast body; 
         FIG. 2  shows a perspective view of the cast body including a part of the connector arrangement of the motor vehicle secondary assembly of  FIG. 1 ; and 
         FIG. 3  shows a partial view of a longitudinal section of the connector arrangement of the motor vehicle secondary assembly of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION 
     The electric motor vehicle secondary assembly of the present invention comprises an electronically commutated drive motor driving the working device, for example, an impeller. The motor control is substantially located on a motor control circuit board which can, for example, be arranged in a transversal plane of the drive motor, i.e., a plane oriented transversely to the rotational axis of the drive motor. The motor control circuit board is at least partly encapsulated in a plastic cast body so as to in particular protect the thus potted electronics against humidity, the electronics being, for example, commutation electronics. 
     A plurality of rigid metal pin elements are electrically connected, for example, soldered, to the motor control circuit board, which, at their free ends, also form the connector pins of the peripheral connector arrangement. No further contact plane thus exists between the electric connection of the pin elements to the motor control circuit board and the connector pins. The electric reliability of the secondary assembly is thereby fundamentally increased. 
     The cast body has a connector core integrally formed thereon which encloses the pin elements so that the connector pins are not potted, while the pin elements are completely potted in the cast body between the connector pins and the motor control circuit board. At its distal end, the connector core forms a connector base from which the connector pins protrude upwards. The connector arrangement may have a connector collar that surrounds the connector pins. The connector collar may be formed by the cast body or by the housing body. 
     The housing body closes the assembly housing and has a housing opening into which the connector core is inserted, or through which the connector core is inserted, so that the connector base of the connector core fully encloses the housing opening. 
     The connector pins of the connector arrangement are thus formed by a plurality of rigid metal pin elements which are directly electrically connected, for example, soldered, to the motor control circuit board. The motor control circuit board including the connector pins is further reliably protected against humidity by a monolithic cast body and is mechanically formed into a single rigid structure so that, for example, vibration-related or assembly-related relative movements between the connector pins or the pin elements and the motor control circuit board are virtually excluded. All effects described together result in a high electric reliability of the motor vehicle secondary assembly. 
     In an embodiment of the present invention, the cast body can, for example, have at least two axial support noses by which the cast body is axially supported at the housing body. The cast body can, for example, have exactly three support noses by which the cast body is axially supported at the housing body. Due to the support noses, the cast body including the connector arrangement is positioned at a defined distance and in a defined spatial position with respect to the housing body. The support noses may of course alternatively be provided at the housing body according to the present invention. 
     In an embodiment of the present invention, the housing body can, for example, have at least two axial support sockets in which the corresponding support noses are supported axially. The term “support socket” is basically to be understood as any form of recess into which the corresponding support nose can protrude. In this manner, the support sockets in particular define the rotational position of the cast body including the connector arrangement and the motor control circuit board relative to the assembly housing or the respective housing body. An erroneous assembly is thereby reliably prevented during the mounting of the secondary assembly. The support noses and the corresponding support sockets can, for example, form a form fit which defines, for example, the rotational position, the radial position, and the axial position of the cast body relative to the respective housing body. The support noses may also basically be provided on the side of the housing body, and the support sockets may be provided on the side of the cast body. 
     In an embodiment of the present invention, the connector core can, for example, be seated on a connector socket that has a larger lateral outer circumference than the connector core. A circumferential shoulder is formed between the connector core and the connector socket, the shoulder lying, for example, in a transverse plane, wherein an elastic ring seal is arranged between the annular surface of the shoulder and a corresponding housing-side sealing surface. A reliable fluidic sealing of the housing interior is thereby achieved in this region. 
     The motor control circuit board, which can, for example, be arranged in a transverse plane, has a proximal side and a distal side. The proximal side is the side of the circuit board that faces the motor rotor and the motor stator in the axial direction. One or both sides can, for example, be at least partly potted or covered by the cast body. Specifically, those parts of the two circuit board sides are covered by the cast body that are equipped with electronic components. The electronic components are thereby fixed and protected against corrosion so that the electric solder connections between the electronic components and the conductor paths on the circuit board will not be damaged even over the long term. 
     In an embodiment of the present in invention, the connector core and the housing opening can, for example, be aligned axially. During the axial mounting of the secondary assembly, it is thereby possible to set the housing body axially on a second housing body which, together with the first housing body, forms the secondary assembly housing. 
     In an embodiment of the present invention, the cast body can, for example, be made of a thermoset molding compound. Compressive load molding compounds cure irreversibly and completely so that no gap can occur at the interface between the cast body and the connector pins even in the long term through which, for example, water vapor can enter the housing interior. Thermoset materials are also reactive so that a substance-to-substance bond between the thermoset of the cast body and the connector pins can be achieved which is and remains virtually impermeable to gas even in the long term. 
     In an embodiment of the present invention, the cast body can, for example, also form a connector holder laterally surrounding the connector pins, wherein the connector frame, together with the connector core, protrudes outward through the housing opening. The connector frame substantially serves to guide a corresponding part of a mating connector. 
     An embodiment of the present invention will be explained below under reference to the drawings. 
       FIG. 1  is a longitudinal section of an electric motor vehicle secondary assembly  10  in the exemplary form of a water recirculation pump. The electric motor vehicle secondary assembly  10  has an electric drive motor  14  coaxially driving a working device  18  in the form of an impeller. The electric motor vehicle secondary assembly  10  has a housing  12  substantially assembled in an axial direction from a first plastic housing body  26  and a second plastic housing body  24 . The second plastic housing body  24  has a coaxial and tube-like pump inlet  20  and a tangential pump outlet  22 . The first plastic housing body  26  has a pot-like design and substantially accommodates the electric drive motor  14 . 
     The electric drive motor  14  is designed as a so-called canned motor and comprises a cylindrical can  32  and a can bottom  33  lying in a transverse plane, the can  32  and the can bottom  33  together forming a so-called integral can that may be made of a plastic material or a non-magnetic metal. The can  32  separates a motor rotor  30 , designed as an internal rotor and excited by permanent magnets, radially from a motor stator  28  that carries a plurality of motor coils  82  in the circumferential direction. The electric drive motor  14  further has commutation electronics  80  on a motor control circuit board  34  lying in a transverse plane, by which the motor coils  82  of the motor stator  28  can be driven or energized. A transverse plane should be understood as a plane that is almost perpendicular to the rotational axis of the motor rotor  30 . 
     The motor control circuit board  34  including the commutation electronics  80  is embedded or potted for the greater part in a monolithic cast body  40  which is formed from a thermoset. As can in particular be seen in  FIG. 2 , the cast body  40  comprises a disc-shaped part  43  that covers almost all of the distal side  37  of the motor control circuit board  34 , an annular part  42  that covers an annular edge strip of the proximal side  35  of the motor control circuit board  34 , and a cylindrical part  41  that integrally connects the disc-shaped part  43  and the annular part  42  of the cast body  40  on the radial outer side. 
     On the distal side, the cast body  40  further has a connector socket  46  protruding upward in the axial direction from the disc-shaped part  43  of the cast body  40 , which connector socket  46  is adjoined in the axial direction by a connector core  48 . A circumferential shoulder  64  is formed between the connector socket  46  and the connector core  48 , the shoulder surface  64 ′ thereof approximately lying in a transverse plane. The connector socket  46  and the connector core  48  enclose three pin elements  51  which protrude axially and almost vertically from the motor control circuit board  34  in the distal direction and are soldered to the motor control circuit board  34 . The three pin elements  51  stand approximately in a row, i.e., they lie in a single longitudinal plane. The three pin elements  51  are longer in the axial direction than the cast body  40 , the sections of the three pin elements  51  that axially protrude above the cast body  40  and are exposed, forming three connector pins  50  of a connector arrangement  16 . 
     The first (pot-shaped) plastic housing body  26  has a substantially cylindrical circumferential wall and a disc-shaped housing body front wall  84  substantially lying in a transverse plane. The housing body front wall  84  has an axial opening  60  into which the connector core  48  is fully inserted. A circumferential sealing surface  67  is provided on the proximal side of the housing body front wall  84 , which corresponds to the shoulder surface  64 ′. An elastic ring seal  65  is arranged between the circumferential sealing surface  67  and the shoulder surface  64 ′ which, in this region, provides a gas-tight sealing of the housing interior from the environment. 
     The distal end side of the connector core  48  forms a connector base  49  of the connector arrangement  16  that lies approximately in a transverse plane. 
     The connector arrangement  16  further comprises a connector frame  52  that surrounds the three connector pins  50  at a distance. In the present case, the connector frame  52  is an integral part of the housing body front wall  84 , but may, as an alternative, generally also be formed by the cast body  40 . 
     On the distal side of the cast body  40  or of its disc-shaped part  43 , two recesses  66 ′ are provided at the edge thereof, since two motor coil clamp terminals  66  protrude from the motor control circuit board  34  in this region, into which a contact pin of the motor coils  82  is inserted through corresponding openings  66 ″, respectively, in the assembled state of the electric motor vehicle secondary assembly  10 . 
     Three axial support noses  44 ,  44 ′ are further formed on the distal side of the cast body  40  at the outer edge of the disc-shaped part  43 , which are supported on three axial support sockets  62  on the proximal side of the housing front wall  84  and/or which engage into the three axial support sockets  62  in a form-fitting manner. The exact axial position of the cast body  40  and the rotational position of the cast body  40  are thereby adjusted or defined relative to the housing  12 . 
     The present invention is not limited to embodiments described herein; reference should be had to the appended claims.