BE1031043B1 - Auxiliary drive for a steering system of a motor vehicle - Google Patents

Abstract

The present invention relates to an auxiliary drive (18) for a steering system (1) of a motor vehicle, comprising a motor (4) with a motor housing (41) which is connected to a transmission housing (51) of a transmission (5) via a flange connection which is axial with respect to a drive axle (A), comprising corresponding flange elements (42, 52) arranged on the motor housing (41) and the transmission housing (51), each of which has an axial end face (421, 521) remote from the housing and a rear face (422, 522) axially opposite thereto, close to the housing, wherein the end faces (421, 521) and the rear faces (422, 522) protrude radially outwards, and a clamping means (7) engages the flange elements (521, 522), which clamps the end faces (421, 422) of the flange elements (42, 52) axially against one another. In order to enable a reduced manufacturing and assembly effort, the invention proposes that the clamping means has at least one clamp element (7) which engages around the flange elements (42, 52) from the outside and has clamping legs (75) which can be clamped axially from the outside against the rear sides (521, 522).

Description

" BE2022/5927

Auxiliary drive for a steering system of a motor vehicle

State of the art

The invention relates to an auxiliary drive for a steering system of a motor vehicle, comprising a motor with a motor housing that is connected to a transmission housing of a transmission via a flange connection axially connected to a drive axle, comprising corresponding flange elements arranged on the motor housing and the transmission housing, each of which has an axial front side remote from the housing and a rear side axially opposite thereto, close to the housing, wherein the front sides and the rear sides protrude radially outwards, and a clamping means engages the flange elements, which clamps the front sides of the

Flange elements are axially clamped against each other.

In the state of the art, motor vehicle steering systems with auxiliary power assistance are known in which, in addition to the steering torque which is manually exerted by the driver on the steering wheel, an auxiliary force or an auxiliary torque is introduced into the steering line by an electro-mechanical auxiliary power drive to support and relieve the driver, and if necessary also an additional steering angle.

An auxiliary drive comprises an electric motor for generating the auxiliary torque, which is coupled to the steering shaft via a gear. The gear is designed as a reduction gear and usually comprises a drive wheel coupled to the motor shaft, for example a worm shaft, which is connected to a

Gear wheel is in gear engagement, for example with a corresponding worm wheel.

A generic auxiliary drive is known in the state of the art, for example in the

WO 2020/048668 A1 or JP 2018161940 A. The gear has a gear housing in which the worm shaft and the worm wheel are accommodated. The

The motor has a motor housing which is connected to the gearbox housing by means of a flange connection such that the motor shaft is axially aligned with the worm shaft in relation to the drive axis. The flange connection comprises two corresponding flange elements.

These are designed as flange rings, each of which protrudes radially beyond the housing, and

? BE2022/5927 whose front sides, each directed axially away from the housing, rest against each other in the connection position. From the rear side closest to the housing, which is axially opposite the front side, fastening screws are led through a plurality of axial flange holes through both flange rings and screwed in such a way that the flange rings are axially clamped against each other and fixed.

The well-known flange connection offers reliable fixation. The disadvantage, however, is the high cost of production due to the creation of the flange holes and the high cost of assembly, during which a large number of screws must be inserted and tightened. The necessary accessibility using a screwing tool limits the structural design freedom and installation space optimization.

An auxiliary drive of the type mentioned above is known from DE 10 2021 201431 A1 or the

KR 101 570 884 B1 known.

In view of the problems explained above, it is an object of the present invention to enable reduced manufacturing and assembly costs.

Description of the invention

This object is achieved according to the invention by the auxiliary drive with the features of the

Claim 1. Advantageous further developments arise from the subclaims.

In an auxiliary drive for a steering system of a motor vehicle, comprising a motor with a motor housing that is connected to a transmission housing of a transmission via a flange connection axial with respect to a drive axle, comprising corresponding flange elements arranged on the motor housing and the transmission housing, each of which has an axial front side remote from the housing and a rear side axially opposite thereto, close to the housing, wherein the front sides and the rear sides protrude radially outwards, and a clamping means engages the flange elements, which clamps the front sides of the flange elements axially against one another, it is provided according to the invention that the clamping means has at least one clamp element that radially surrounds the flange elements from the outside and has clamping legs that can be clamped axially from the outside against the rear sides.

° BE2022/5927

According to the invention, the flange elements are not clamped together by means of bolts or screws that pass through flange bores, as in the prior art, but are clamped against one another by at least one clamp element attached from the outside.

The clamp element is at least partially bow-shaped. It has a

Longitudinal plane in which the drive axis lies, has a substantially U-shaped cross-sectional profile that is open radially inwards, towards the longitudinal axis. The clamping legs protrude from the clamp element, viewed from the outer circumference of the flange elements, radially inwards towards the drive axis, and are arranged relative to one another with an axial distance that corresponds to the inner width of the U-profile. The two flange elements, which in their connection position are axially against one another with their front sides, are between the

Clamping legs can be accommodated, whereby the clamping legs grip the two flange elements. The clamping legs exert a clamping force axially from both sides onto the rear sides, through which the flange elements are pressed and clamped axially against each other to create a durable flange connection.

To assemble the flange connection, one or preferably several clamp elements can simply be placed radially from the outside onto the flange elements that are in the axial connection position with their end faces facing each other, so that they grip around them with their essentially U-shaped cross-sectional profile like a clamp or pliers and thereby fix them in their connection position in a form-fitting manner in the axial direction. This makes assembly less complex than with screws or other flange connecting means known in the prior art and can advantageously be automated. The radial assembly makes access easier. Because, in contrast to the prior art, no flange holes need to be drilled into the flange elements, they can be manufactured more easily and more cost-effectively, for example as cast parts that require no or at least less subsequent machining. In addition, the flange connection can be created without contamination from abrasion or particles that can be created by self-tapping screws, for example, and which could potentially disrupt the function if they penetrate.

The rear sides can advantageously be conical, and the basic U-shaped cross-sectional profile of the clamp element can also be correspondingly conical on the inside, with the clamping legs being arranged in a correspondingly conical manner, i.e. in the

Cross section radially from inside to outside in a V-shape. Due to the wedge effect

° BE2022/5927 When the clamp element is attached radially, the flange elements are clamped axially against each other with their front sides.

It is advantageous that the clamping legs have spring elements. The spring elements are axially effective, i.e. they are designed to be springy in the axial direction to generate a spring force which is exerted as an elastic tension force on the backs of the flange elements held between the clamping legs. The spring force can be generated simply as an elastic restoring force by the axial distance between the opposing clamping legs in the undeformed state before installation being smaller than the sum of the axial thicknesses measured between the front and back of the flange elements arranged against each other in the connection position. This means that when radially plugging onto the

Flange elements bend the clamping legs axially apart and load the rear sides with their elastic restoring force. It is possible for the clamping legs to have spring elements on both axial sides, or only on one side.

Preferably, a clamping leg can be designed to be resilient, for example in the manner of a leaf spring. Its end section, which points radially inwards in the installed position, can be elastically bent in the axial direction and rest against the rear of the flange element to transmit the clamping force. Such a design can be provided with the required properties with little effort.

The flange elements can be designed as flange rings. The flange rings are

The basic shape is ring-shaped, preferably circular and arranged coaxially to the drive axis. Between the front and rear sides, a flange ring can preferably have a substantially cylindrical outer circumferential surface. This forms a circumferential contour that is circular at least in sections in the circumferential direction.

It can preferably be provided that a clamp element extends in the circumferential direction at least in sections along an outer circumferential contour of the flange elements.

The circumferential contour can be circular in its entirety or in sections, for example in the case of a circular flange ring, or in the case of a flange element with a different shape, for example oval, polygonal or the like. Because the clamp element is shaped according to the circumferential contour, it can cling to the flange elements in the installation position, so that an advantageously small installation space is required.

> BE2022/5927

It is particularly possible that a clamp element is bent to match the outer peripheral contour of the flange elements. The basic profile of the clamp element, which is U-shaped in cross section, is

Clamp element, from which the clamping legs extend radially inwards, bent following the circumferential contour.

It is preferred that a clamp element is formed in a segment-shaped manner. The segment-shaped

The clamp element extends in the circumferential direction over a circular section and can also be referred to as a clamp segment. This extends in relation to the drive axis over an angular segment of less than 360° and in the circumferential direction over a circumferential section that is smaller than the total circumference. The clamp segment can preferably enclose an angular segment of less than or equal to 180°, correspondingly less than or equal to half the total circumference. One advantage of the clamp segment is that it can be simply attached in a radial direction inwards, towards the drive axis, onto the flange elements arranged in the connection position. This allows the

Assembly effort can be reduced.

An advantageous further development is that a clamp element has a plurality of clamping legs adjacent in the circumferential direction. In this design, the clamp legs are narrower than the clamp element when measured in the circumferential direction. A plurality of these narrow clamp legs are arranged next to one another on the clamp element in the circumferential direction. For example, the clamp legs can have narrow clamping tongues that radiate radially inwards from the clamp element bent along a circumferential contour, for example in the shape of a circular arc. Radial incisions or interruptions are formed between the clamp tongues. The clamp tongues are individually and independently elastically flexible in the axial direction, so that all clamp tongues rest against the flange element without play, so that the clamping force is safe and uniform.

Big is transferred to the flange element over the entire extent of the clamp element. Due to the radial cuts between the clamping tongues, the entire clamp element can be bent as a whole across the circumferential direction despite the U-shaped cross-section that is rigid in the area of the individual clamping tongues. This makes assembly easier and ensures that the clamp element sits firmly on the flange elements without play.

Preferably, it can be provided that at least one flange element is designed as a flange segment, extends in the circumferential direction between two transverse end surfaces, and the clamp element has retaining legs that encompass the end surfaces in the circumferential direction.

° BE2022/5927. In this design, the flange element is not designed to run around the entire circumference, but extends as a flange segment over a circular segment.

The clamp element is preferably designed as described above as

Clamp segment, which essentially has the same angle segment as the

In addition to the axial clamping legs, which axially surround the flange elements, the clamp element has two retaining legs, which

Enclose the flange segment in the circumferential direction, i.e. on both sides in the circumferential direction against the

end surfaces.

Like the clamping legs, the retaining legs also protrude radially inwards from the clamp element, but extend from the circumferential ends of the clamp segment adapted to the flange segment. The retaining legs protrude into the axial space between the axially spaced clamping legs, in other words into the space formed by the open U-profile cross-section in which the flange elements are received in the connecting position and are axially clamped between the clamping legs. The retaining legs preferably have an axial width that is adapted to the axial distance between the clamping legs.

In any case, the retaining legs should be wide enough in the axial direction to rest against the circumferential end faces of both flange elements facing each other in the connection position. The flange segments are thus held together by the

The retaining legs are positively locked against relative rotation around the drive axis and held in a defined angular orientation.

It is advantageous that the holding legs have spring elements. The spring elements are in

Circumferential direction elastic, and thus enable the clamp element to be placed in the radial direction on the flange element, whereby the retaining legs are elastically bent apart in the circumferential direction, and in the installed position resiliently against the circumferential

end surfaces.

Preferably, a holding leg can be designed to be resilient, for example in the manner of a leaf spring. Its end section, which points radially inwards in the installed position, can be elastically bent in the axial direction and can rest against the circumferential end surface of the flange segment(s) to hold the clamp element. Such a design can be provided with the required properties with little effort.

It can advantageously be provided that the clamp element and the flange rings have corresponding locking elements which engage in an elastic, positive locking engagement

/ BE2022/5927. Corresponding locking elements can be arranged on the clamping legs and the axial rear sides of the flange elements, and additionally or alternatively on the holding legs and the circumferential end surfaces of the flange rings.

The locking elements can preferably be designed so that when the

clamping element, the clamping legs are elastically spread apart in the axial direction and the holding legs are elastically spread apart in the circumferential direction, in order to then snap into the corresponding locking elements on the backs or the end surfaces in a form-fitting manner due to the elastic tension when the end position is reached. Due to the fact that the locking elements are axially or circumferentially snapped into place when the

When the clamping element snaps into the flange elements and engages with each other in a form-fitting manner, a clear mounting position is achieved in the installation position and the clamping element is held securely. This simplifies assembly and securely fixes the flange connection.

The locking elements can, for example, comprise recesses or undercuts and corresponding projections on the flange element and on the clamping and/or holding legs of the clamp element that can be brought into positive engagement with springs. This enables simple assembly, in which the clamp element is pushed on radially until it snaps into place with springs. The locking elements can be integrated into the flange element in one piece with little effort.

Cast parts or sheet metal parts are molded or formed.

It can preferably be provided that two or more flange elements and corresponding clamp elements are arranged distributed over the circumference. The flange elements and the clamp elements can preferably be arranged evenly distributed over the circumference.

It is advantageous for a clamp element to be designed as a sheet metal part. The sheet metal part can preferably be designed in one piece, including the clamping legs and/or the holding legs. It can be efficiently manufactured as a stamped and pressed part, preferably from spring steel sheet, so that the clamping and holding legs can be integrated in one piece as leaf springs.

It is possible that the engine housing and/or the transmission housing contain castings.

For example, the housings can be made of metal casting, for example aluminum or magnesium die casting. It is also possible to manufacture them from thermoplastic

Plastic, preferably fiber-reinforced or the like, in the plastic injection molding process. In any case, it can be provided that the flange elements are integrally attached to the

The motor housing and/or the gearbox housing are integrally formed, which means that the manufacturing effort can be advantageously low.

Description of the drawings

Advantageous embodiments of the invention are explained in more detail below with reference to the drawings. In detail:

Figure 1 shows a motor vehicle steering in a schematic perspective view,

Figure 2 shows an auxiliary drive according to the invention in a first embodiment in a schematic perspective view,

Figure 3 is another view of the auxiliary drive according to Figure 2,

Figure 4 is an enlarged partial view of the auxiliary drive according to Figure 2 in partial,

Figure 5 is a front view of a flange connection according to the invention,

Figure 6 is a plan view of a flange connection according to the invention as shown in Figure 5,

Figure 7 is an isometric view of a flange connection according to the invention according to

Figure 5,

Figure 8 is an isometric view of a clamp element according to the invention.

Embodiments of the invention

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

° BE2022/5927

Figure 1 shows a schematic representation of a motor vehicle steering system designed as an electromechanical power steering system 1. This has a steering column 2 with a support unit 21 that can be attached to a body (not shown) of a motor vehicle.

In the steering column 2, a steering shaft 10 is mounted so as to be rotatable about its longitudinal axis L. At its rear end with respect to the direction of travel, this has a fastening section 11 to which a steering wheel 12 is attached in a rotationally fixed manner, via which a driver can introduce a steering torque (manual torque) into the steering shaft 10 as a steering command.

The steering torque is transmitted via the steering shaft 10, which has interposed universal joints 13 for adaptation to the installation position in the motor vehicle, to a steering pinion 14, which engages in a longitudinally displaceable rack 15. This converts a rotation of the steering shaft 10 during a steering intervention into a displacement of tie rods 16, as indicated by the double arrow, which transmit the specified steering intervention as a steering angle to the steerable wheels 17 of the motor vehicle.

An electric power assist can be a control unit attached to the steering column 2,

The steering wheel can have an auxiliary drive 3 coupled to the steering shaft 10, or an auxiliary drive 31 coupled to the pinion 14 with the steering shaft 10, whereby the auxiliary drives 3 and 31 can be constructed in the same way. The auxiliary drive 3 or 31 can couple an auxiliary torque into the steering shaft 1 and/or the steering pinion 14 in order to assist the driver with the steering work.

An auxiliary drive 18 can also be provided to provide a steering-assisting

Auxiliary force must be introduced into the rack 15.

Usually, an auxiliary drive 3, 31 or 18 is only attached to one of the three positions shown. The auxiliary torque or the auxiliary force that is to be applied to support the driver by means of the respective auxiliary drive 3, 31 or 18 is determined taking into account a steering torque determined by a torque sensor 19 and manually applied by the driver. Alternatively or in combination with the application of the auxiliary torque, the auxiliary drives 3, 31, 18 can be used to introduce an additional steering angle into the

steering system, which corresponds to the force applied by the driver via the steering wheel 12.

steering angle is summed.

To explain the function, reference is made below to the auxiliary drive 3 designed according to the invention, which is shown in different representations in Figures 2 to 8.

The torque sensor 19 is used to detect the manual torque applied to the steering shaft 10, for example in a manner known per se by measuring the torsion of a torsion bar integrated into the steering shaft 10. An auxiliary torque is determined via an electrical control unit (not shown) and an electrical control signal derived therefrom is fed into an electric motor 4 of the auxiliary drive 3. The electromotive torque generated in this way is coupled into the steering shaft 10 via a gear 5 of the electrical auxiliary drive 3 to support the manual steering work.

The motor 4 has a motor housing 41 in which a motor shaft (not explicitly shown here) is mounted so as to be rotatable about a drive axis A. A gear 5 is arranged in a known manner

For example, it is designed as a worm gear in order to transmit the drive torque of the motor shaft as an auxiliary torque to the steering shaft 10.

The motor housing 41 is connected to the gear housing 51 of a gearbox 5 by a flange connection according to the invention, which is explained in detail below in Figures 4 to 8.

Figure 4 shows an enlarged detailed view of the motor housing 41 and the gear housing 51, Figure 5 shows the flange connection schematically in an axial view with respect to the drive axis A, Figure 6 shows a radial side view and Figure 7 shows a schematic perspective view.

A flange element 42 according to the invention is formed on the motor housing 41, which is designed as a flange segment 42, which extends as a circular section of a drive axis

A coaxial flange ring in the example shown extends over an angle a of approximately 120°, as can be seen in Figure 5.

A flange element 52 according to the invention is formed on the gear housing 51, which is designed as a flange segment 52, which, viewed in the axial direction, is congruent with the

flange element 42 of the motor housing 41.

In the connection position shown, an end face 421 of the flange segment 42 facing away from the motor housing 41 rests against an axially opposite, corresponding end face 521 of the flange segment 52 of the gear housing 51.

The flange segment 42 has a housing-near, axially facing motor housing 41

rear side 422, which is axially opposite to the front side 421. Accordingly, the

Flange segment 52 has a rear side 522 that faces axially toward the gear housing 51 and is close to the housing and is axially opposite the front side 521. The rear sides 422 and 522 are conical and converge radially outward in the connection position, as can be seen in Figure 6.

In the circumferential direction, each flange segment 42, 52 is connected by transverse

End surfaces 43, 53.

In the example shown, the flange segments 42 and 52 are designed to be mirror-symmetrical to a mirror plane in which the end faces 421 and 521 lie axially against one another.

As can be seen in Figure 5, two flange segments 42 and 52 are arranged opposite one another in mirror image with respect to the drive axis A and evenly distributed over the circumference.

For fixing, a clamp element 7 according to the invention, which is shown separately in a perspective view in Figure 8, is placed in a radial direction inwards towards the drive axis A on the flange elements 42 and 52, as shown in Figure 5 on the right

side is indicated by the arrow. The clamp element 7 on the left side of Figure 5 is fully assembled.

The clamp element 7 extends as a clamp segment in the circumferential direction essentially also over the angle a and is curved following the circular outer contour of the flange segments 42 and 52, as can be seen in Figure 5. It has a

A plurality of radially inwardly directed clamping legs distributed over the circumference in the form of clamping tongues 74 and 75. The clamping tongues 74 are arranged axially at a distance from the clamping tongues 75. The clamping tongues 74 are arranged conically inclined to the opposite clamping tongues 75, the inclination of the conical

Back sides 422 and 522 of the flange segments 41 and 51 can be adapted.

At the two circumferential ends, the clamp element 7 has holding legs 76 which can be bent outwards in a spring-elastic manner in the circumferential direction, as indicated in Figures 5, 7 and 8 with the arrows.

For assembly, a clamp element 7 is moved in the radial direction until the flange segments 42 and 52 are axially received between the clamping tongues 74 and 75, and the clamping tongues 74 and 75 rest against the rear sides 422 and 522. The conical arrangement of the clamping tongues 74, 75 and the rear sides 422, 522 exerts an axial clamping force through the wedge effect, which clamps the front sides 421 and 521 axially against each other.

When the clamp element 7 is attached, the spring-elastic holding elements 76 snap into place behind the two end surfaces 43 and 53, so that the clamp element 7 shown on the left in Figure 5

The assembly state shown on the left is realized. This fixes the clamp element 7.

Because the holding elements 76 extend in the axial direction over both end surfaces 42 and 52, the flange segments 42 and 52 are positively locked together in a rotationally fixed manner with respect to the drive axis A.

List of reference symbols 1 Power steering 10 Steering shaft 11 Fastening section 12 Steering wheel 13 Universal joint 14 Steering pinion 15 Rack 16 Tie rod 17 Wheel 18 Power drive 19 Torque sensor 2 Steering column 21 Support unit 3,31 Power drive 4 Motor 41 Motor housing 42 Flange segment 421 Front side 422 Rear side 43 End face 5 Gearbox 51 Gearbox housing 52 Flange segment 521 Front side 522 Rear side 53 End face 7 Clamp element 74 Clamping tongue 75 Clamping tongue 76 Holding element

L Longitudinal axis

A drive axle

Claims (14)

PATENT CLAIMS 1. Auxiliary drive (18) for a steering system (1) of a motor vehicle, comprising an engine (4) with an engine housing (41) that is connected to a transmission housing (51) of a transmission (5) via a flange connection axially relative to a drive axle (A), comprising corresponding flange elements (42, 52) arranged on the engine housing (41) and the transmission housing (51), each of which has an axial front side (421, 521) remote from the housing and a rear side (422, 522) axially opposite thereto, close to the housing, wherein the front sides (421, 521) and the rear sides (422, 522) project radially outward, and a clamping means (7) engages the flange elements (42, 52), which clamps the front sides (421, 521) of the flange elements (42, 52) axially against each other. clamped together, characterized in that the clamping means has at least one clamp element (7) which engages radially from the outside around the flange elements (42, 52) and has clamping legs (75) which can be clamped axially from the outside against the rear sides (521, 522). 2. Auxiliary drive according to claim 1, characterized in that the clamping legs (75) have spring elements. 3. Auxiliary drive according to one of the preceding claims, characterized in that the flange elements (42, 52) are designed as flange rings. 4. Auxiliary drive according to one of the preceding claims, characterized in that a clamp element (7) extends in the circumferential direction at least in sections along an outer circumferential contour of the flange elements (42, 52). 5. Auxiliary drive according to one of the preceding claims, characterized in that a clamp element (7) is bent according to an outer peripheral contour of the flange elements (42, 52). 6. Auxiliary drive according to one of the preceding claims, characterized in that a clamp element (7) is segment-shaped. 7. Auxiliary drive according to one of the preceding claims, characterized in that a clamp element (7) has a plurality of clamping legs (74, 75) adjacent in the circumferential direction. 8. Auxiliary drive according to one of the preceding claims, characterized in that at least one flange element (42, 52) is designed as a flange segment, extends in the circumferential direction between two end faces (53) transverse to the circumferential direction, and the clamp element (7) has holding legs (76) which engage around the end faces (53) in the circumferential direction. 9. Auxiliary drive according to one of the preceding claims, characterized in that the holding legs (76) have spring elements. 10. Auxiliary drive according to one of the preceding claims, characterized in that the clamp element (7) and the flange rings (42, 52) have corresponding locking elements which can be brought into an elastic, positive locking engagement. 11. Auxiliary drive according to one of the preceding claims, characterized in that two or more flange elements (42, 52) and corresponding clamp elements (7) are arranged distributed over the circumference. 12. Auxiliary drive according to one of the preceding claims, characterized in that a clamp element (7) is preferably designed as a one-piece sheet metal part. 13. Auxiliary drive according to one of the preceding claims, characterized in that the motor housing (41) and/or the gear housing (51) comprise cast parts. 14. Auxiliary drive according to one of the preceding claims, characterized in that the flange elements (42, 52) are integrally formed on the motor housing (41) and/or the gear housing (51).