DRIVE UNIT OF AN ELECTRICAL POWER-ASSISTED STEERING SYSTEM FOR A MOTOR VEHICLE

Abstract

A drive unit for an electrical power-assisted steering system of a motor vehicle may include an electric motor with a stator housing to which a control housing, in which a control circuit board is arranged, is attached, and with a connecting unit, attached to the stator housing, which has electrical connecting elements and at least one positioning element. The connecting elements are electrically connected to the electric motor and to the control circuit board. The positioning element interacts with the control circuit board for the purpose of relative positioning. To enable simpler and more secure mounting, the positioning element interacts with the control housing for the purpose of relative positioning.

Claims

1.-13. (canceled)

14. A drive unit for an electrical power-assisted steering system of a motor vehicle, comprising: an electric motor with a stator housing that is attached to a control housing; a control circuit board disposed in the control housing; and a connecting unit attached to the stator housing, the connecting unit having electrical connecting elements and a positioning element, wherein the electrical connecting elements are electrically connected to the electric motor and to the control circuit board, wherein the positioning element interacts with the control circuit board for the purpose of relative positioning, wherein the positioning element interacts with the control housing for the purpose of relative positioning.

15. The drive unit of claim 14 wherein the positioning element engages in a form-fitting manner in a corresponding positioning socket in the control housing.

16. The drive unit of claim 14 wherein the positioning element includes a positioning pin that is aligned in an axial direction.

17. The drive unit of claim 14 wherein the positioning element is a first positioning element, the first positioning element projecting farther from the stator housing than a second positioning element.

18. The drive unit of claim 14 wherein the positioning element includes a first positioning section for engaging in the control housing and a second positioning section for engaging in the control circuit board.

19. The drive unit of claim 14 wherein the positioning element includes a connecting element.

20. The drive unit of claim 14 wherein at least one of the connecting elements has a coating of non-conductive material at least in some places.

21. The drive unit of claim 14 wherein a side of the control housing that is remote from the stator housing is closed with a control housing lid.

22. A method for producing a drive unit for an electrical power-assisted steering system of a motor vehicle, in which a control housing, in which a control circuit board is arranged, is attached to a stator housing of an electric motor, wherein a connecting unit having electrical connecting elements and a positioning element is attached to the stator housing, the method comprising: positioning and fixing the connecting unit on the stator housing; aligning the control housing on the positioning element of the connecting unit and fixing the control housing relative to the stator housing; and aligning the control circuit board on the positioning element and fixing the control circuit board relative to the stator housing.

23. The method of claim 22 comprising fastening undetachably the connecting unit on the positioning element that projects relative to the stator housing and/or to the connecting unit in an axial direction of the stator housing.

24. The method of claim 22 wherein the positioning element includes a positioning pin that extends in an axial direction and onto which the control housing and the control circuit board with corresponding positioning sockets are pushed in the axial direction.

25. The method of claim 24 wherein the control housing is positioned on a first positioning section of the positioning element and the control circuit board is positioned on a second positioning section of the positioning element.

26. The method of claim 22 wherein the electrical connecting elements of the connecting unit are electrically connected to corresponding connection elements of phase windings and the control circuit board.

Description

DESCRIPTION OF THE DRAWINGS

[0047] Advantageous embodiments of the invention are explained in detail below with the aid of the drawings, in which:

[0048] FIG. 1 shows a power-assisted steering system for a motor vehicle in a schematic perspective illustration,

[0049] FIG. 2 shows a drive unit of a power-assisted steering system according to FIG. 1,

[0050] FIG. 3 shows the drive unit according to FIG. 2 in a schematic illustration in which it is pulled apart in the axial direction,

[0051] FIG. 4 shows a schematic illustration of the drive unit according to FIG. 2 or 3 in a first mounting state of the method according to the invention,

[0052] FIG. 5 shows a schematic illustration in a second mounting state, following FIG. 4,

[0053] FIG. 6 shows a schematic illustration in a third mounting state, following FIG. 5,

[0054] FIG. 7 shows a side view of the mounting state shown in FIG. 5,

[0055] FIG. 8 shows a schematic illustration in a fourth mounting state, following FIG. 6,

[0056] FIG. 9 shows a schematic illustration in a fifth mounting state, following FIG. 8,

[0057] FIG. 10 shows a schematic illustration in a sixth mounting state, following FIG. 9,

[0058] FIG. 11 shows a schematic illustration in in the fully mounted final state, as in FIG. 2,

[0059] FIG. 12 shows a connecting unit of a drive unit according to FIGS. 1 to 11 in a schematically pulled-apart illustration,

[0060] FIG. 13 shows a schematic illustration of the drive unit in a second embodiment in a first mounting state in a view corresponding to FIG. 8,

[0061] FIG. 14 shows the drive unit according to FIG. 13 in a view corresponding to FIG. 5,

[0062] FIG. 15 shows the drive unit according to FIG. 14 in a view corresponding to FIG. 4,

[0063] FIG. 16 shows a connecting unit of a drive unit according to FIGS. 13 to 15 in a schematic perspective view,

[0064] FIG. 17 shows the connecting unit according to FIG. 16 in a further schematic perspective view similar to FIG. 4,

[0065] FIG. 18 shows a connecting unit of a drive unit according to FIGS. 13 to 17 in a schematically pulled-apart illustration.

EMBODIMENTS OF THE INVENTION

[0066] In the different Figures, the same parts are at all times provided with the same reference symbols and are therefore generally also each mentioned only once.

[0067] FIG. 1 shows a power-assisted steering system 1 which is attached to a steering shaft 2 which is mounted rotatably 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 2 in torque-locking fashion and so that it can be adjusted telescopically in the longitudinal direction. At its rear end with respect to the driving direction, the steering shaft 2 has a fastening section 23 for attaching a steering wheel (not illustrated).

[0068] An electrical power-assistance drive 3 has a gearbox, preferably a worm gear, the output wheel of which is coupled non-rotatably to the steering shaft 2, namely to the inner shaft 21.

[0069] A drive unit 4 according to the invention, which is shown separately in a dismounted state in FIG. 2, is attached to the gearbox 31 on the input side.

[0070] The drive unit 4 has an electric motor 41. The motor 41 has a stator housing 5 in which a rotor shaft 42 is mounted rotatably about a rotor axis R. The rotor axis R defines the axial direction of the drive unit 4. A clutch 43, which can be designed as a claw clutch in this example, is attached to the rotor shaft 42 on the gearbox side for the purpose of torque-locking connection to the gearbox 31.

[0071] FIG. 3 shows the drive unit 4 in an exploded illustration in which the individual components are illustrated, pulled apart in the axial direction of the rotor axis R.

[0072] Phase windings 44 are attached in the stator housing 5.

[0073] A connecting unit 6, which has positioning elements designed as positioning pins 61 projecting in parallel and axially, is attached to the stator housing 5 axially on the side remote from the gearbox 31.

[0074] A control housing 7, which protrudes beyond the cross-section of the stator housing 5 transversely to the rotor axis R and has positioning sockets designed as through openings 71 into which the positioning pins 61 can be pushed in the axial direction and which house the latter in form-fitting fashion, is attached to the stator housing 5.

[0075] A control circuit board 8, also referred to as a printed circuit board or PCB and on which a control circuit with non-electronic components is constructed and interconnected, is arranged in an interior, remote from the stator housing 5, of the control housing 7. It has positioning sockets designed as through openings 81 which are axially aligned with the positioning sockets 71 of the connecting unit 7. The positioning pins 61 are designed such that in the mounted state they project axially from the control housing 7 through the through openings 71 and can be pushed axially into the through openings 81 of the control circuit board 8 for mounting.

[0076] By attaching a lid 9, the control circuit board 8 is enclosed tightly in the control housing 7. A plug housing 91, into which an electrical connector (not illustrated) can be plugged for connection to power-supply contacts of the control circuit board 8, is attached between the lid 9 and the control circuit board 8.

[0077] The production of a drive unit 1 according to the method according to the invention is shown in successive mounting states in FIGS. 4 to 10.

[0078] It can be seen in FIG. 4 that the connecting unit 6 has a common connecting body 62, designed 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 which are made from a metal material that is a good conductor. The contact pins 64 projecting 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 designed so that they are stepped in the axial direction.

[0079] The connecting body 62 has axial through fastening openings 65 which correspond with axially projecting pin-shaped fastening projections 45, so-called bobbins, on the stator housing 5.

[0080] Starting from the mounting state shown in FIG. 4, the connecting unit 6 is moved in the direction of the arrow axially toward the stator housing 5 until the fastening projections 45 penetrate the fastening openings 65 in form-fitting fashion and are secured there by caulking, riveting, adhesive bonding, or the like such that the connecting unit is fixed as shown in FIG. 5.

[0081] In the next step, as shown in FIGS. 6 and 7, the control housing 7 is positioned relative to the stator housing 5 such that the through openings 71 are axially aligned with the positioning pins 61.

[0082] It can be clearly seen in the side view transversely to the axial direction in FIG. 7 that, in the example shown, two of the positioning pins 61a project axially further than the others, and the positioning pins 61 have a length or height L2 which is longer than the length L1 of the positioning pins 61. If the control housing 7 is then moved axially toward the stator housing 5 for mounting, the positioning pins 61a first penetrate the associated through openings 71a, as a result of which relative orientation and alignment of the control housing 7 are effected such that the insertion of the other positioning pins 61 into the associated through openings 71 is ensured. The through openings 71, 71a of the control housing 7 can have different diameters so that the positioning pins 61, 61a can be positioned and pushed through more simply.

[0083] In the mounting state shown in FIG. 8, the control housing 7 is positioned relative to the connecting unit 6 and hence also to the stator housing 5 by the positioning pins 61, 61a passing through the through openings 71, 71a in form-fitting fashion with their first positioning sections 63 (see FIG. 7). The second positioning sections 64 of the positioning pins 61, 61a thus project axially from the control housing 7.

[0084] The control circuit board 8 is then, as shown in FIG. 9, positioned axially relative to the control housing 7 such 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.

[0085] The control circuit board 8 is thereupon moved in the axial direction toward the control housing 7 until first the axially further projecting positioning pins 61a, and then the other positioning pins 61, are pushed through the corresponding through openings 81a until the mounting state shown in FIG. 10 is obtained. The control circuit board 8 is now situated in the control housing 7 and, like the latter, is aligned on the same positioning pins 61 transversely to the axial direction. Because the internal diameter of the through openings 81 is adapted so that it matches exactly the diameter or cross-section of the second positioning sections 64, precise positioning can be produced. In order to avoid mechanical redundancy and stress states, individual or multiple through openings 81, 81a are designed as elongated holes which have play in the transverse direction, as a result of which the alignment of the control circuit board 8 relative to the control housing 7 is, however, not adversely affected. The through openings 81, 81a of the control circuit board 8 can have different diameters so that the positioning pins 61, 61a can be positioned and pushed through more simply.

[0086] In the mounting state in FIG. 10, the control circuit board 8 sits axially on the axial step surface formed between the first positioning sections 63 and the second positioning sections 64. As a result, precise axial positioning of the control circuit board 8 relative to the control housing 7 is additionally enabled. The positioning pins 61, 61a consequently have a positioning effect simultaneously in and transversely to the axial direction.

[0087] The projecting positioning sections 64 can be connected to the control circuit board 8, for example by soldering. As a result, in addition to the mechanical positioning and fixing, a conductive connection is produced between the contact pins having the second positioning sections 64 and the control circuit constructed on the control circuit board 8.

[0088] The control housing 7 is then closed by the axial attachment of the lid 9 such that the control circuit board 8 is enclosed therein, as in the final state of mounting in FIG. 11, which corresponds to the state in FIG. 2. The plug housing 91 can be clamped, for example, between the lid 9 and the control circuit board 8.

[0089] The connecting unit 6 is illustrated in FIG. 12, schematically pulled apart, wherein the second positioning sections 64 which are formed by metal contact pins 64, preferably formed from wire, are illustrated separately from the connecting body formed from the plastic injection-molding process. The bent connecting sections 66 can be clearly seen here which face essentially in the same direction (upward in the drawings) as the contact pins 64 but are here considerably shorter. These connecting sections 66 can be connected conductively to the phase windings 44, for example by crimping, press-fitting, soldering, and/or welding, or the like to the ends of the winding wire of these phase windings 44.

[0090] FIGS. 13, 14, and 15 show a second embodiment of a drive unit 4 according to the invention, wherein the same reference symbols are used for parts which have the same effect. The view in FIG. 13 corresponds to the view in FIG. 8, in FIG. 14 to FIG. 9, and in FIG. 15 to FIG. 4 together with FIG. 9.

[0091] The connecting unit 6 in the second embodiment is shown in FIG. 17 in a perspective view as for the first embodiment in FIG. 4, and in FIG. 16 in a further perspective view. FIG. 18 shows a schematically pulled-apart illustration similar to FIG. 12.

[0092] It can be seen with the aid of the separate illustration in FIGS. 16 and 17 that the connecting unit 6 has a flat connecting body 62 which is annular with respect to the rotor axis R and can likewise 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, formed by the contact pins 64 and projecting parallel to the rotor axis R, of the contact pins 64 form positioning pins 61. It can clearly be seen here in FIG. 17 that all the positioning pins 61 project axially from the connecting body 62 by the same amount.

[0093] The positioning pins 61 are passed through positioning sections 63 which are formed as a single piece with the connecting body 62 and project axially from the latter in the direction of the rotor axis R,

[0094] Two neutral point connectors 67, which can be formed, for example, as sheet-metal parts, are attached preferably undetachably to the connecting body 62, for example by welding. The neutral point connectors 67 are formed from a material which is a good conductor, for example from copper, and each have at least three contact tabs 68 which can be connected conductively at the neutral point to those ends of the winding wires of the three phase windings 44 which are on the neutral point side. The contact tabs 68 can likewise, as illustrated, be angled at the neutral point connector and project in the direction of the rotor axis R.

[0095] The connecting unit 6 is inserted axially into the stator housing 5 in the direction of the rotor axis R, as indicated by the arrow in FIG. 15. The rotor shaft 42 here passes through the center of the annular connecting body 62.

[0096] In the second embodiment shown, when the connecting unit 6 is mounted, the control housing 7 can be already attached to the stator housing 5. Otherwise, mounting is effected as above with reference to FIGS. 4 and 5. The detailed manner in which this is effected is explained above in connection with FIG. 3.

[0097] When the connecting unit 6 is inserted, as illustrated in FIG. 14, the stator windings 44 are connected to the connecting sections 66 of the contact pins 64 and the contact tabs 68 of the neutral point connectors 67.

[0098] The control circuit board 8 is then inserted into the stator housing 5 in the axial direction predetermined by the rotor axis R, as indicated by the arrow in FIG. 14. The positioning pins 61 and the positioning sections 63 thus come into engagement with the through openings 81 in the control circuit board 8, as a result of which the latter is fixed in position.

[0099] FIG. 18 shows a schematically pulled-apart illustration of the connecting unit 6. The contact pins 64 formed by wire sections are embedded in the connecting body 62 formed as a plastic injection-molded part, as has already been described above for the first embodiment in FIG. 12. The neutral point connectors 67 can likewise be injection-molded or be attached later.

LIST OF REFERENCE SYMBOLS

[0100] 1 power-assisted steering system [0101] 2 steering shaft [0102] 21 inner shaft [0103] 22 outer shaft [0104] 23 fastening section [0105] 3 power-assistance drive [0106] 31 gearbox [0107] 4 drive unit [0108] 41 motor [0109] 42 rotor shaft [0110] 43 clutch [0111] 44 phase winding [0112] 45 fastening projections [0113] 5 stator housing [0114] 6 connecting unit [0115] 61,61a positioning pins [0116] 62 connecting body [0117] 63 first positioning section [0118] 64 second positioning section (contact pin) [0119] 65 fastening openings [0120] 66 connecting sections [0121] 67 neutral point connector [0122] 68 contact tabs [0123] 7 control housing [0124] 71 through openings [0125] 8 control circuit board [0126] 81 through openings [0127] 9 lid [0128] 91 plug housing [0129] R rotor axis