DRIVE UNIT OF AN ELECTRIC ASSISTANCE STEERING SYSTEM FOR A MOTOR VEHICLE

Description

State of the art

[0001] The invention relates to a drive unit for an electric power steering system of a motor vehicle, comprising an electric motor with a stator housing to which a control housing is attached, in which a control board is arranged, and with a connecting unit attached to the stator housing, which has electrical connecting elements and at least one positioning element, wherein the connecting elements are electrically connected to the electric motor and to the control board and the positioning element cooperates with the control board for relative positioning, wherein the positioning element cooperates with the control housing for relative positioning.

[0002] Motor vehicle steering systems with power assistance are known in the prior art, in which, in addition to the steering torque manually exerted by the driver on the steering wheel, an auxiliary force is introduced into the steering train by an electro-mechanical auxiliary power assistance to support and relieve the driver, and if necessary also an additional steering angle.

[0003] The auxiliary power is generated by means of an electric auxiliary drive, which has a drive unit with an electric motor, the rotor shaft of which is coupled to the steering train via an auxiliary power transmission.

[0004] A drive unit of this type is known in the prior art, for example from DE 10 2018 216 744 A1. This comprises a motor with a stator housing in which the stator or phase windings are mounted, and in which the rotor is rotatably mounted with the rotor shaft arranged in the axial direction. The motor is electrically controlled by an electrical control circuit having electrical components arranged and interconnected on a control board, also referred to as a printed circuit board or PCB. This control board is arranged in a control housing, also referred to as a control or control board housing, which is connected to the stator housing to form a compact assembly, also referred to as a power pack. The electrical and mechanical connection between the phase windings of the motor and the control board is established via a connecting unit.On the one hand, this is fixed to the stator housing and connected to the phase windings of the motor, and on the other hand, it is connected to the control housing and connected to the control board.

[0005] In the known drive unit, the connecting unit has positioning elements in the form of positioning pins that positively engage corresponding receiving openings in the control board. The positioning elements interact with the control board in such a way that the control board is positioned and aligned relative to the connecting unit, and thus to the stator housing. When assembled, the control board is protected within the control housing. A disadvantage, however, is that the control housing is not aligned, or only insufficiently aligned, relative to the control board. The control housing itself is attached to the stator housing or the connecting unit.Because the alignment of the control board relative to the control housing causes the tolerances of the connections between the stator housing, connection unit and control board to add up, the assembly of the control board can be more difficult and there is an increased risk of damage during assembly.

[0006] A drive unit of the type mentioned above is known in the prior art, for example, from JP 2013 106376 A, JP 2018 125948 A, US 2015 / 222156 A1, US 2014 / 125173 A1, or EP 1 955 927 A1. A disadvantage of all the designs described therein is that assembly is complicated.

[0007] In view of the problems explained above, it is an object of the present invention to enable a simpler and safer assembly of a drive unit. Description of the invention

[0008] This object is achieved according to the invention by the drive unit having the features of claim 1. Advantageous further developments emerge from the subclaims.

[0009] In a drive unit for an electric power steering system of a motor vehicle, comprising an electric motor with a stator housing to which a control housing is attached, in which a control board is arranged, and with a connecting unit attached to the stator housing, which has electrical connecting elements and at least one positioning element, wherein the connecting elements are electrically connected to the electric motor and to the control board and the positioning element cooperates with the control board for relative positioning, wherein the positioning element cooperates with the control housing for relative positioning, it is provided according to the invention that at least one positioning element protrudes further from the stator housing relative to another positioning element.

[0010] According to the invention, the at least one positioning element that protrudes further is longer than the other positioning element(s) or than the connecting element(s). The longer positioning element is preferably at least 1 mm longer or at least 2 mm longer than the other positioning or connecting element. Because a positioning element, preferably designed as a positioning pin, protrudes further axially, in the axial direction, it can be inserted axially into a corresponding positioning receptacle, preferably a receiving opening, while still enabling a relative orientation of the other positioning element(s) that are further back axially with respect to the mounting direction and do not yet engage in the corresponding positioning receptacles.As soon as one or two protruding positioning elements are positively inserted into the defined installation position, the remaining positioning elements are automatically aligned with the corresponding positioning mounts and can be mounted with further axial movement. This simplifies assembly.

[0011] Particularly preferably, the electric motor is arranged in the stator housing, which comprises a stator with stator or phase windings, in which a rotor with a rotor shaft lying in the axial direction is rotatably mounted.

[0012] The connecting unit is positioned and fixed to the stator housing and provides at least one positioning element according to the invention, preferably a plurality of positioning elements. According to the invention, the positioning element is designed and configured to enable the precise alignment of both the control board and the control housing relative to the connecting unit. In other words, the control board and the control housing are each aligned directly on the positioning element and thus positioned and aligned parallel to one another on the same positioning element relative to the connecting unit, and not via a serial arrangement of connections as in the prior art. Thus, the unavoidable and potentially damaging addition of the tolerances of the serially arranged connections in the prior art is avoided, and improved and more precise positioning of the control board and the control housing is ensured.The improved dimensional accuracy of the arrangement simplifies assembly, particularly in automated production. The relative orientation between the control housing and the positioning element is largely independent of tolerances, so that the inventive alignment of the control board to this positioning element ensures a correspondingly precise alignment of the control board relative to the control housing. This reproducible, low-tolerance alignment simplifies assembly and reduces the risk of damage due to relative misalignment when inserting the control board into the control housing and when assembling the connections between the connection unit and the control board.

[0013] The advantageous effects arise in particular from the fact that the positioning element(s) according to the invention provide, for the first time, a common reference position for the alignment and orientation of the control housing and control board, whereby tolerance-related problems and the risk of damage during assembly can be reduced and largely avoided.

[0014] The control housing can be fixed to the stator housing, for example, flange-mounted, for example, by means of fastening bolts that are passed through corresponding fastening holes and screwed together. A sufficiently large predefined play can ensure fixation in the relative positioning defined by the positioning elements. The control housing can, for example, be fixed to the stator housing at the end face with respect to an axial direction defined by the rotor axis, preferably externally, for example, by a flange connection. Alternatively or additionally, detachable and / or non-detachable connecting means can be provided for fixing the control housing in the relative positioning to the connecting unit and to the stator housing, as predetermined by the positioning element(s) according to the invention.

[0015] The control board can be aligned and fixed to the positioning element(s) according to the invention when the control housing is positioned and fixed relative to the positioning elements. The control board can be detachably or permanently connected to at least one positioning element, or alternatively or additionally to the control housing.

[0016] The simultaneous positioning and fixation of the control board on a positioning element offers the advantage of efficient assembly. The positioning element(s) can simultaneously serve as fastening elements or connecting elements between the connection unit and the control board and / or the control housing. The fixation can be detachable or non-detachable, for example, by soldering, gluing, pressing, screwing, clamping, or the like. It is conceivable and possible to design the connection to be electrically conductive and to create an electrical connection between the connection unit and the control board using an electrically conductive positioning element.

[0017] This reduces manufacturing and assembly costs. Thus, some positioning elements are designed as phase connectors for the electric motor, while the others serve as positioning elements.

[0018] The control housing can protrude outward beyond the cross-section of the stator housing, for example, laterally perpendicular to the axial direction of the rotor axis. This makes it possible to use a control board that is larger than the installation space available in the internal cross-section of the stator housing. This also enables improved cooling of the electronic components mounted on the control board. These are further advantages over the prior art, in which the control board is arranged together with the control housing within the stator housing, which can limit the installation space and the options for heat dissipation.

[0019] It can be provided that at least one positioning element engages in a corresponding positioning receptacle in the control housing with a positive fit. For this purpose, the positioning receptacle can, for example, have a recess or a through-opening, preferably extending in the axial direction, into which the positioning element can be inserted in an assembly direction to form a positive fit. The assembly direction can preferably correspond to the axial direction, and the positive fit can be effective in this direction and / or transversely thereto. The positioning element(s) can also engage in corresponding positioning receptacles in the control board, for example, with a positive fit in recesses or through-openings.

[0020] An effective design that can be implemented with little effort is for at least one positioning element to have a positioning pin aligned in an axial direction of the motor. The connecting unit can preferably be attached to the stator housing such that one or more positioning pins protrude axially at the front. The corresponding positioning receptacles in the control housing and the control board can simply be designed as openings or recesses into which the positioning pin can be accommodated by simply inserting it axially. Preferably, an axially continuous through-opening can be provided, for example in the control housing, through which a positioning pin can be inserted in the axial direction.The control board can be positioned and, if necessary, secured on a section of a positioning pin that protrudes axially from the through-hole of the control housing, a positioning section, using a corresponding positioning receptacle, also a recess or opening. Such an arrangement of positioning pins and corresponding positioning receptacles can be implemented with little effort and enables simple and secure installation. During assembly, the control housing can be plugged onto the positioning pin(s) first, followed by the control board.

[0021] A positioning pin can have a circular or non-circular cross-section, such as a polygonal or other shaped cross-section, which corresponds to the internal cross-section of a receiving opening of a positioning receptacle. This enables easy insertion in the axial direction, which corresponds to an axial mounting direction. By appropriately adapting the shape and dimensions, a positive fit can be created transversely to the mounting direction. If necessary, a defined clearance can also be provided, for example by forming an elongated hole or slot, whereby tolerances in one direction can be compensated for without negatively affecting the relative alignment of the control housing and control board according to the invention.

[0022] It can be provided that at least one positioning element has at least a first positioning section for engagement in the control housing and at least a second positioning section for engagement in the control board. The first positioning section can, for example, have a larger cross-section than the second positioning section, for example a larger diameter in the case of a positioning pin. For example, a positioning pin can be designed that is stepped in the axial direction. The control housing can be plugged onto the first positioning section in a form-fitting manner in the axial assembly direction over the second positioning section using a positioning receptacle designed as a through-opening. In the finished assembled state, when the control housing is sitting on the first positioning section and is fixed in place, the second assembly section protrudes axially from the control housing.The control board can now be plugged onto this protruding second positioning section in the axial mounting direction until the second positioning section fits snugly into the corresponding positioning recess of the control board. This allows the control board to be aligned relative to the positioning element and thus simultaneously relative to the control housing.

[0023] The positioning receptacles of the control housing and the control board can have different diameters compared to the other positioning receptacles to simplify positioning and insertion of the at least one longer and axially further protruding positioning element.

[0024] It is possible for at least one positioning element to have a connecting element. This allows a connecting element to be integrated with a positioning element. For example, a connecting or contact element can have a positioning pin with an integrated electrical conductor, for example, made of a metallic material. The contact element can be designed, for example, as a contact pin made of a wire.

[0025] It is possible for a connecting element to have a sheath made of non-conductive material, at least in sections. One or more connecting elements can, for example, each have a contact pin, which can additionally also have a positioning section of a positioning element or serve as such. One or more such connecting elements or contact pins can, for example, be encased in a plastic overmolding made of a thermoplastic, electrically insulating plastic. In this way, the sheath can have one or more insulated sections, which can also be designed as positioning sections of a positioning element according to the invention.

[0026] The contact pins can be provided as preferably bent wire sections, which have positioning sections protruding from the plastic axially in the direction of the rotor axis. Connecting sections can be provided at the end regions facing away from the positioning sections for conductive connection to the wire ends of the phase windings. The connecting sections can be angled to simplify the assembly process and the creation of a conductive connection, for example, by crimping or welding.

[0027] For embedding in the connector body, the finished, bent contact pins can be inserted into the injection mold and then overmolded with molten plastic. The positioning sections then protrude from the plastic as bare wire sections.

[0028] An advantageous development can provide for a plurality of positioning elements to be integrally connected to one another, preferably as a plastic injection-molded part. This allows a connecting unit including the positioning elements to be provided as an injection-molded part, preferably made of thermoplastic, in a cost-effective manner and with low dimensional tolerances. An advantageous development can provide for one or more connecting elements, for example, metallic contact pins, to be embedded in the plastic injection-molded part of the connecting unit. It can be particularly advantageous to embed a connecting or contact element in a positioning element.This integration enables advantageous multiple functionality: For example, in plastic injection molding, a stepped positioning pin as described above can be provided with little effort and high accuracy, and several such positioning pins can be integrated in one piece with a connecting unit.

[0029] For mounting the connecting unit on the stator housing, corresponding fastening elements can preferably be provided, which are releasably or permanently fixed to one another. The fastening elements are preferably designed and configured so that they can be joined together in an axial assembly direction and subsequently fixed in place. For example, the fastening elements can have pins—so-called bobbins—and corresponding receiving openings, which can be joined together in a form-fitting manner. A permanent connection can be achieved efficiently, securely, and with dimensionally accurate means by welding, gluing, caulking, riveting, or the like.

[0030] An advantageous further development can provide that the control housing is closed with a control housing cover on its side facing away from the stator housing, so that the electronic components of the control board and other sensitive elements of the motor are protected against dirt and moisture.

[0031] To assemble a drive unit according to the invention, a stator housing is first provided in which the rotor of the electric motor can already be rotatably mounted ready for operation. A connecting unit can preferably be fixed to the stator housing on the end face in the axial assembly direction, as described above. For example, corresponding fastening elements of the connecting unit and the stator housing can preferably be assembled and fixed to one another in a form-fitting manner in the axial assembly direction. As a result, the connecting unit is fixed in position relative to the stator housing in such a way that the positioning element(s) according to the invention are positioned and aligned for subsequent assembly of the control housing. The positioning elements can preferably have at least one positioning pin projecting axially on the end face, preferably a plurality of pin-shaped, elongated positioning pins.

[0032] The control housing is then aligned with at least one positioning element of the connecting unit and fixed relative to the stator housing. During alignment, one or more fastening receptacles, preferably through-holes, are arranged axially aligned in front of the corresponding positioning elements, preferably positioning pins. By an axial assembly movement, the control housing is plugged onto the connecting unit in the axial direction until the positioning pins preferably engage in the corresponding positioning openings with a form-fitting fit, and are preferably seated on corresponding first positioning sections. The positioning elements preferably protrude axially beyond the control housing with second positioning sections. Thanks to the invention, these second positioning sections are precisely positioned relative to the control housing simply by plugging them on.

[0033] The control board is then aligned with the positioning element and fixed relative to the stator housing. For alignment, a corresponding positioning receptacle, for example, an axial positioning opening in the control board, is arranged axially aligned in front of the positioning element, which is preferably designed as a positioning pin. The control board is then moved toward the control housing in the axial assembly direction until it is inserted therein and the second positioning sections of the positioning pin(s) engage positively in the corresponding positioning openings of the control board. This automatically aligns the control board with the positioning element(s) and thus simultaneously relative to the control housing.

[0034] The control board can then be fixed detachably or permanently, for example, by soldering, gluing, pressing, screwing, clamping, or the like. It is conceivable and possible to design the connection to be electrically conductive. Preferably, the control board can be secured to the positioning element(s). By fixing the control board, the control housing, which is located below the control board with respect to the mounting direction, can also be fixed to the connection unit.

[0035] The connecting unit is preferably connected to the stator windings via electrical connecting elements and to the control board via connecting elements. The connecting elements can be integrated into the positioning elements and, for example, comprise a conductive pin that is preferably mechanically and electrically connected to the control board via an electrically conductive connection such as soldering or the like.

[0036] An advantage of the method according to the invention is that the positioning element(s) are automatically aligned during assembly of the control housing, allowing the subsequent assembly of the control board onto this or these positioning elements to be carried out easily and precisely. This reduces the risk of damage during assembly, especially in automated assembly processes.

[0037] Preferably, the connecting unit can be permanently fastened to one or more fastening elements that protrude relative to the stator housing and / or the connecting unit in an axial direction of the stator housing. The axial direction is predetermined by the rotor axis. The fastening elements can, for example, comprise one or more fastening pins or projections protruding axially from the front end, or so-called bobbins, onto which the connecting unit is axially pushed and fixed with corresponding fastening openings, for example by riveting, pressing, or the like. Form-fitting, interacting fastening elements allow for precise alignment of the connecting unit relative to the stator housing.

[0038] Preferably, the positioning elements can have at least one positioning pin extending in an axial direction, onto which the control housing and the control board are plugged in the axial direction with corresponding positioning receptacles. The axial plugging enables particularly simple assembly. Receiving openings in the control board and / or the control housing can be formed as positioning receptacles with little effort.

[0039] During assembly, the control housing can be positioned at a first positioning section of the positioning element, and the control board can be positioned at a second positioning section. Positioning transverse to the assembly direction can be achieved simply by positive engagement of the respective positioning section in a corresponding positioning receptacle or opening. For example, a positioning pin can be stepped and have axially successive positioning sections with different diameters and / or cross-sections. Then, for assembly, the control housing can first be axially pushed onto the first positioning section, followed by the control board.

[0040] The control board can be fixed to at least one of the positioning elements, for example, by a permanent or detachable connection. This allows the control housing to be fixed to the positioning pin at the same time.

[0041] During assembly, it can preferably be provided that electrical connecting elements of the connecting unit are electrically connected to corresponding connection elements on the stator and the control board. The electrical connection can be created together or simultaneously with the mechanical connection, for example, by soldering, crimping, or the like, or also by detachable connectors or the like.

[0042] After mounting the control housing on the stator housing and attaching the control board in the control housing, the latter can be closed by attaching a cover or a control housing cover so that the control board is preferably sealed and enclosed.

[0043] At least one star-point connector can be attached to the connecting body. A star-point connector is made of a highly conductive material, for example copper, and has at least three contact elements, such as contact tabs or lugs, which can be conductively connected to the star-point ends of the winding wires of the three phase windings at the star point. A star-point connector can be designed, for example, as a sheet metal or wire molded part and can preferably be permanently attached to the connecting body of the connecting unit, for example by welding. The contact elements can also be angled on the star-point connector, as shown, and protrude from the connecting unit in the direction of the rotor axis. One advantage is that the star point can be integrated with the connecting unit with little effort, thereby simplifying assembly and saving installation space. Description of the drawings

[0044] Advantageous embodiments of the invention are explained in more detail below with reference to the drawings. In detail: Figure 1 shows a power steering system for a motor vehicle in a schematic perspective view, Figure 2 shows a drive unit of a power steering system according to Figure 1 , Figure 3 the drive unit according to Figure 2 in a schematic representation exploded in the axial direction, Figure 4 a schematic representation of the drive unit according to Figure 2 or 3 in a first assembly state of the method according to the invention, Figure 5 a schematic representation in a second, Figure 4 following assembly state, Figure 6 a schematic representation in a third, on Figure 5 following assembly state, Figure 7 a side view of the Figure 5 shown assembly state, Figure 8 a schematic representation in a fourth, on Figure 6following assembly state, Figure 9 a schematic representation in a fifth, on Figure 8 following assembly state, Figure 10 a schematic representation in a sixth, on Figure 9 following assembly state, Figure 11 a schematic representation in the fully assembled final state as in Figure 2 , Figure 12 a connecting unit of a drive unit according to Figures 1 to 11 in a schematic exploded view, Figure 13 a schematic representation of the drive unit in a second embodiment in a first assembly state in a view corresponding to Figure 8, Figure 14 the drive unit according to Figure 13 in a view according to Figure 5 , Figure 15 the drive unit according to Figure 14 in a view according to Figure 4 , Figure 16 a connecting unit of a drive unit according to Figures 13 to 15 in a schematic perspective view, Figure 17 the connecting unit according to Figure 16in another schematic perspective view similar Figure 4 , Figure 18 a connecting unit of a drive unit according to Figures 13 to 17 in a schematic exploded view. Embodiments of the invention

[0045] In the various figures, identical parts are always provided with the same reference symbols and are therefore usually named or mentioned only once.

[0046] Figure 1 shows a power steering system 1 mounted on a steering shaft 2, which is rotatably mounted about its longitudinal axis L, the steering shaft axis. The steering shaft 2 has an inner shaft 21, which is arranged in an outer shaft 22 in a torque-locking manner and is telescopically adjustable in the longitudinal direction. At its rear end, relative to the direction of travel, the steering shaft 2 has a fastening section 23 for attaching a steering wheel (not shown).

[0047] An electric auxiliary drive 3 has a gear 31, preferably a worm gear, whose output gear is non-rotatably coupled to the steering shaft 2, namely to the inner shaft 21.

[0048] On the input side, a drive unit 4 according to the invention is attached to the transmission 31, which Figure 2 is shown separately in disassembled condition.

[0049] The drive unit 4 has an electric motor 41. The motor 41 has a stator housing 5 in which a rotor shaft 42 is rotatably mounted about a rotor axis R. The rotor axis R defines the axial direction of the drive unit 4. For a torque-locking connection to the transmission 31, a clutch 43, which in this example can be designed as a claw clutch, is attached to the rotor shaft 42 on the transmission side.

[0050] Figure 3shows the drive unit 4 in an exploded view in which the individual components are shown pulled apart in the axial direction of the rotor axis R.

[0051] Phase windings 44 are mounted in the stator housing 5.

[0052] A connecting unit 6 is attached axially to the stator housing 5 on the side facing away from the gear 31, which connecting unit has positioning elements designed as parallel axially projecting positioning pins 61.

[0053] A control housing 7 is mounted on the stator housing 5, which projects beyond the cross section of the stator housing 5 transversely to the rotor axis R, and has positioning receptacles designed as through openings 71, into which the positioning pins 61 can be inserted in the axial direction and receive them in a form-fitting manner.

[0054] In an interior of the control housing 7 facing away from the stator housing 5, there is a control circuit board 8, also referred to as a printed circuit board or PCB (printed circuit board), on which a control circuit with unspecified electronic components is constructed and interconnected. This board has positioning receptacles designed as through-openings 81, which are axially aligned with the positioning receptacles 71 of the connecting unit 7. The positioning pins 61 are designed such that, in the assembled state, they protrude axially through the through-openings 71 from the control housing 7 and can be inserted axially into the through-openings 81 of the control circuit board 8 for assembly.

[0055] By attaching a cover 9, the control board 8 is tightly enclosed in the control housing 7. Between the cover 9 and the control board 8, a connector housing 91 is mounted, into which an electrical connector (not shown) can be inserted for connection to the supply contacts of the control board 7.

[0056] In the Figures 4 to 10 the production of a drive unit 1 according to the method according to the invention is shown in successive assembly states.

[0057] In Figure 4It can be seen that the connecting unit 6 has a common connecting body 62 formed as a plastic injection-molded part, from which the positioning pins 61 protrude axially. The positioning pins 61 have a first positioning section 63, which is formed by a plastic overmolding of electrically conductive contact pins made of a highly conductive metallic material. The contact pins 64 protruding axially from the first positioning section 63 form second positioning sections 64, which have a smaller cross-section than the first positioning sections 63. The positioning pins 61 are thus stepped in the axial direction.

[0058] The connecting body 62 has axially continuous fastening openings 65 which correspond to axially projecting, pin-shaped fastening projections 45 - so-called bobbins - on the stator housing 5.

[0059] Based on the Figure 4In the assembly state shown, the connecting unit 6 is moved axially in the direction of the arrow against the stator housing 5 until the fastening projections 45 engage positively in the fastening openings 65 and are fixed there by caulking, riveting, gluing or the like so that the connecting unit as shown in Figure 5 shown is fixed.

[0060] In the next step, as in Figures 6 and 7 shown the control housing 7 is positioned relative to the stator housing 5 so that the through openings 71 are axially aligned with the positioning pins 61.

[0061] In the side view transverse to the axis direction in Figure 7It is clearly visible that in the example shown, two of the positioning pins 61 protrude axially further than the others; the positioning pins 61a have a length or height L2 which is longer than the length L1 of the positioning pins 61. If the control housing 7 is now moved axially against the stator housing 5 for assembly, the positioning pins 61a first enter the associated through-openings 71a, thereby ensuring relative orientation and alignment of the control housing 7, ensuring that the remaining positioning pins 61 are inserted into the associated through-openings 71. The through-openings 71, 71a of the control housing 7 can have different diameters to simplify positioning and insertion of the positioning pins 61, 61a.

[0062] In the Figure 8In the assembly state shown, the control housing 7 is positioned relative to the connecting unit 6 and thus also to the stator housing 5 in that the positioning pins 61, 61a with their first positioning sections 63 (see Figure 7 ) penetrate the through-openings 71, 71a in a form-fitting manner. The second positioning sections 64 of the positioning pins 61, 61a protrude axially from the control housing 7.

[0063] Then, as in Figure 9 shown, the control board 8 is positioned axially relative to the control housing 7 so that the through openings 81 are axially aligned with the positioning pins 61, namely with the positioning sections 64 projecting axially from the control housing 7.

[0064] The control board 8 is then moved in the axial direction towards the control housing 7 until first the axially further projecting positioning pins 61a are inserted through the corresponding through-openings 81a, and then the remaining positioning pins 61, until the Figure 10The assembly state shown is reached. The control board 8 is now located in the control housing 7 and, like the latter, is aligned transversely to the axial direction using the same positioning pins 61. Because the inner diameter of the through-openings 81 is precisely matched to the diameter or cross-section of the second positioning sections 64, precise positioning can be achieved. To avoid mechanical over-determination and stress conditions, one or more of the through-openings 81, 81a can be designed as elongated holes that have play in the transverse direction, although this does not impair the alignment of the control board 8 relative to the control housing 7. The through-openings 81, 81a of the control board 8 can have different diameters to simplify positioning and insertion of the positioning pins 61, 61a.

[0065] In the assembled state of Figure 10The control board 7 sits axially on the axial stepped surface formed between the first positioning sections 63 and the second positioning sections 64. This additionally enables precise axial positioning of the control board 8 relative to the control housing 7. The positioning pins 61, 61a therefore have a positioning effect simultaneously in and transverse to the axial direction.

[0066] The protruding positioning sections 64 can be connected to the control board 8, for example, by soldering. In addition to mechanical positioning and fixation, this creates a conductive connection between the contact pins comprising the second positioning sections 64 and the control circuit mounted on the control board 8.

[0067] Subsequently, the control housing 7 is closed by axially attaching the cover 9 so that the control board 8 is enclosed therein, as in the final state of assembly in Figure 11 , which corresponds to the state of Figure 2 The connector housing 91 can, for example, be clamped between the cover 9 and the control board 8.

[0068] In the Figure 12 The connecting unit 6 is shown schematically exploded, with the second positioning sections 64, which are formed by metallic contact pins 64, preferably made of wire, shown separately from the connecting body formed from injection-molded plastic. This clearly shows the bent connecting sections 66, which point essentially in the same direction (upward in the drawing) as the contact pins 64, but are significantly shorter. These connecting sections 66 can be conductively connected to the phase windings 44, for example by crimping, pressing, soldering and / or welding or the like to the ends of the winding wire of these phase windings 44.

[0069] The Figures 13, 14 and 15 show a second embodiment of a drive unit 4 according to the invention, wherein the same reference numerals are used for identical parts. The view of Figure 13 corresponds to the view of Figure 8 , Figure 14 with Figure 9, and Figure 15 with Figure 4 together with Figure 9 .

[0070] The connecting unit 6 in the second embodiment in Figure 17 in a perspective view like the first version in Figure 4 shown, and in Figure 16 in another perspective view. Figure 18 shows a schematic exploded view similar to Figure 12 .

[0071] Based on the separate presentation in Figures 16 and 17It can be seen that the connecting unit 6 has a flat connecting body 62, which is annular with respect to the rotor axis R and which can also preferably be formed as a plastic injection-molded part. Contact pins 64 formed from wire sections - also referred to as second positioning pins - are firmly embedded in the connecting body 62, preferably by overmolding with the plastic in the injection molding process. The end sections of the contact pins 64 formed by the contact pins 64 and projecting parallel to the rotor axis R form positioning pins 61. Figure 17 It is clearly visible that all positioning pins 61 protrude axially from the connecting body 62 by the same distance.

[0072] The positioning pins 61 are guided through positioning sections 63 which are formed integrally with the connecting body 62 and project axially therefrom in the direction of the rotor axis R,

[0073] Two star-point connectors 67, which may be formed, for example, as sheet metal parts, are preferably permanently attached to the connecting body 62, for example by welding. The star-point connectors 67 are made of a highly conductive material, for example, copper, and each have at least three contact tabs 68, which can be conductively connected to the star-point ends of the winding wires of the three phase windings 44 at the star point. The contact tabs 68 can also be angled on the star-point connector, as shown, and protrude in the direction of the rotor axis R.

[0074] The connecting unit 6 is inserted axially in the direction of the rotor axis R into the stator housing 5, as shown in Figure 15 indicated by the arrow. The rotor shaft 42 passes centrally through the opening of the annular connecting body 62.

[0075] In the second embodiment shown, the control housing 7 can already be attached to the stator housing 5 during assembly of the connecting unit 6. Otherwise, assembly is carried out as described above. Figures 4 and 5 How this is done in detail is explained above in connection with Figure 3 explained.

[0076] When the connecting unit 6 is inserted as shown in Figure 14 As shown, the stator windings 44 are connected to the connecting sections 66 of the contact pins 64 and the contact tabs 68 of the star point connectors 67.

[0077] The control board 8 is then inserted into the stator housing 5 in the axial direction defined by the rotor axis R, as shown in Figure 14 indicated by the arrow. The positioning pins 61 and the positioning sections 63 engage with the through-holes 81 in the control board 8, thereby securing the board in position.

[0078] Figure 18shows a schematic exploded view of the connecting unit 6. The contact pins 64 formed by wire sections are embedded in the connecting body 62 designed as a plastic injection-molded part, as described above for the first embodiment in Figure 12 as already described. The star-point connectors 67 can also be molded on or injected, or retrofitted. List of reference symbols

[0079] 1 Power steering 2 Steering shaft 21 Inner shaft 22 Outer shaft 23 Mounting section 3 Power assist drive 31 Gearbox 4 Drive unit 41 Motor 42 Rotor shaft 43 Coupling 44 Phase winding 45 Mounting projections 5 Stator housing 6 Connecting unit 61, 61a Positioning pins 62 Connecting body 63 First positioning section 64 Second positioning section (contact pin) 65 Mounting openings 66 Connecting sections 67 Star point connector 68 Contact tabs 7 Control housing 71 Through-holes 8 Control board 81 Through-holes 9 Cover 91 Connector housing RRotor axis

Claims

1. A drive unit (4) for an electrical power-assisted steering system (1) of a motor vehicle, comprising an electric motor (41) with a stator housing (5) to which a control housing (7), in which a control circuit board (8) is arranged, is attached, and with a connecting unit (6), attached to the stator housing (5), which has electrical connecting elements and at least one positioning element (61), wherein the connecting elements are electrically connected to the electric motor (41) and to the control circuit board (8), and the positioning element (61) interacts with the control circuit board (8) for the purpose of relative positioning, wherein the positioning element (61) interacts with the control housing (7) for the purpose of relative positioning, characterized in that at least one positioning element (61a) projects further from the stator housing (5) relative to another positioning element (61a).

2. The drive unit as claimed in claim 1, characterized in that at least one positioning element (61) engages in form-fitting fashion in a corresponding positioning socket (71) in the control housing (7).

3. The drive unit as claimed in one of the preceding claims, characterized in that at least one positioning element (61) has a positioning pin (61) which is aligned in an axial direction.

4. The drive unit as claimed in one of the preceding claims, characterized in that at least one positioning element (61) has at least one first positioning section (63) for engaging in the control housing (7) and at least one second positioning section (64) for engaging in the control circuit board (8).

5. The drive unit as claimed in one of the preceding claims, characterized in that at least one positioning element (61) has a connecting element.

6. The drive unit as claimed in one of the preceding claims, characterized in that a connecting element has a coating of non-conductive material at least in some places.

7. The drive unit as claimed in one of the preceding claims, characterized in that the control housing (7) is closed on its side remote from the stator housing (5) with a control housing lid (9).