DE10353161A1 - Electrical servo-mechanism for automotive power steering has ball screw drive bearing located within electric motor power output wheel - Google Patents

Abstract

An automotive steering mechanism has electrically-powered servo mechanism with a housing (1) around the steering shaft (2) and an electric motor (3) located close the shaft. The motor powers a drive output wheel (7) coupled to second drive output wheel (13) to a ball screw drive (10) that is coupled to the steering shaft. The ball screw drive bearing is located within the output wheel (13).

Description

The The invention relates to a vehicle steering system with an electric Auxiliary drive comprising a housing with a handlebar, an electric motor to produce a Auxiliary power, which is arranged laterally next to the handlebar, a Drive wheel driven by the motor, a driven wheel, the above the drive wheel is driven, and a ball screw, the engages with the handlebar and rotatably with the output gear connected is.

Usually is in such vehicle steering the engine laterally next to the handlebar stated. The power transmission the auxiliary power on the ball screw and thus on the handlebar mostly done over a belt drive.

Known solutions with flanged motors are mainly in relation to the manufacturing and mounting tolerances problematic and easy to install. So must after screwing the engine to the steering gear housing the Belt tension during of the manufacturing process. Additional housing for the engine and a control unit condition a high cost, which is associated with corresponding costs. In the not yet published Patent application of the applicant with the number 103 36 867.1 of 11. August 2003 is in this context a vehicle steering with an electric auxiliary drive of the type of the aforementioned type discloses, which is characterized, the steering gear housing of two housing parts exists and the motor housing and / or an optional control electronics housing with the steering gear housing is integrally formed. This will increase the number of components needed reduced, resulting in a reduction of manufacturing and assembly costs results. Due to the one-piece design of the motor housing or of the control electronics housing with the steering gear housing In addition, the production and Mounting tolerances reduced because the position assignment of the engine too the handlebar by the joint processing of the relevant Sections of the integral housing independently from the cultivation of the engine is.

In this known vehicle steering a single roller bearing is provided for the storage of the ball screw, sitting next to the driven wheel. In contrast, in conventional designs mostly two separate bearings are used on both sides of the driven wheel. Corresponding constructions are used for example in the DE 37 11 099 C2 and the DE 37 12 154 A1 disclosed.

task The present invention is the improvement of these known Vehicle steering with regard to noise behavior and ease of movement of the ball screw.

to solution This object is a vehicle steering with the features of claim 1 proposed. This includes a housing with a handlebar, a electric motor for generating an auxiliary power, the side is arranged next to the handlebar, a drive wheel through is driven by the engine, a driven wheel, which - indirectly or directly - on the Drive wheel is driven, and a ball screw, with the Handlebar is engaged and rotatably connected to the output gear is. The vehicle steering system according to the invention stands opposite the above explained Vehicle steering characterized in that the storage for the ball screw in the case extends into the driven gear or within the driven gear is arranged.

These solution offers several advantages. Through the inventive thought that Bearing of the ball screw substantially or even completely in To move the drive wheel, a virtually torque-free power transmission from the drive wheels over the Ball screw achieved on the handlebar. This will cause the tilt of the ball screw minimizes, resulting in an improvement of the smooth running and a reduced noise results.

By the minimization of the torque resulting from the transmission there is no need for a second warehouse to catch one. The corresponding production, processing and assembly costs are eliminated. moreover the bearing friction remains through the use of only one bearing low.

The Solution according to the invention also allows a safe and inexpensive execution the storage security.

By these measures let yourself also realize an axially particularly compact design of the housing.

Further, advantageous embodiments of the invention are specified in the claims.

According to an advantageous embodiment of the invention, the majority of the storage within the driven wheel is arranged to minimize any moments. If the dimensions of the output gear allow it, the storage can ever but also be arranged completely within it.

Prefers the drive wheel and the output gear are designed as pulleys, the one about Belt drivingly with each other are coupled. However, it is also possible, instead of a belt drive to provide a gearing. Preferably then comb each formed as a gear drive wheel and driven gear together.

To a further advantageous embodiment of the invention the ball screw a ball screw nut. The driven wheel and the storage can then just on the outer circumference the ball screw nut are pushed. This reduces the Machining effort on the part of the ball screw nut and facilitates the assembly. So can these components are combined to form a preassembled unit which then attach themselves to a section of the housing en bloc leaves.

As already mentioned above, storage takes place through a single warehouse. Preferably this a rolling bearing. In an advantageous embodiment, a double row rolling bearing comes For use, which is well able, low levels of disturbance the power transmission chain catch.

in the With regard to the attachment of the above-mentioned unit to a Section of the housing can be designed to facilitate in the output gear mounting holes through which the bearing is pressed with a cup-shaped housing portion of the housing can be. In this way it is possible, for example, first the inner ring of the bearing on the outer circumference of the ball screw nut set. This can be set at the same time the output gear on the ball screw nut become.

About the mounting holes then finally can the outer ring securely on the housing section be determined. The determination of the storage is thereby with realized little effort.

Preferably is the storage in the assembled state of the housing between a shoulder of the drive wheel, which against the inner ring of Storage rests, and a shoulder of the cup-shaped housing portion, which against the outer ring the bearing is applied, held axially.

Especially but not exclusively in those cases in which the case is made of a different material than the outer ring of the storage can the latter by at least one additional fastener across from the cup-shaped housing section be determined. A possibility this involves the use of fasteners in the form of pins.

According to one advantageous embodiment, the storage forms on its outer periphery a groove into which the at least one pin radially engages.

This Pin may be, for example, a conical threaded pin, the with the preferably also conical groove on the outer circumference the storage is braced.

The additional Bracing the storage allows it, housing made of light metal, in particular an aluminum alloy.

Prefers is the case divided transversely to the handlebar. The storage is at a housing part supported. The elements provided for fastening the same are lifting off of the other housing part accessible. This is for the mounting advantageous.

following the invention with reference to an embodiment shown in the drawing explained in more detail. The Drawing shows in:

1 a perspective sectional view of a vehicle steering system according to an embodiment of the invention.

The embodiment refers to a vehicle steering system for a motor vehicle in the form of a Rack and pinion steering with an electric auxiliary drive.

The vehicle steering comprises a housing 1 , which is an axially movable handlebar 2 receives. At the ends of the handlebar 2 connect two tie rods not shown here, each leading to a vehicle. In the case 1 is still an electric motor 3 added to generate an auxiliary power. The motor housing is in the housing 1 integrated. The power of the engine 3 is via a coupling device in an axial movement or support the movement of the handlebar 2 translated.

The housing 1 is from two parts 1a and 1b composed. These are preferably designed as castings. The dividing plane of the housing 1 runs transversely to the handlebar 2 , In the division level is an access to the engine 3 , Its wave 4 is at one end to a wall portion of the first housing part 1a stored. A second bearing for the shaft 4 will be on the opposite side of the motor 3 through a into the first housing part 1a used partition 5 created. The shaft penetrates 4 the partition 5 so that one end section 6 from the first housing part 1a protrudes. On the end section 6 is a drive wheel 7 attached, which is part of a belt drive to be explained in more detail below.

In or on the first housing part 1a All components of the auxiliary drive can be mounted while the second housing part 1b in principle acts like a lid, the after the assembly of the auxiliary drive, the first housing part 1a closes. The first housing part 1a has a handlebar 2 surrounding central section 8th and also a motor housing section 9 on, the side of the central section 8th is formed.

Through the integral integration of the motor housing section 9 in the first housing part 1a eliminates the connection via a motor flange and otherwise required sealing and fastening measures. The one-piece machining of the first housing part 1a allows a good parallelism between the axle of the handlebar 2 and the axis of the motor shaft 4 , In addition, the axial distance between the handlebar axis and the motor axis can be maintained very precisely, so that the timing belt can be mounted without a separate adjustment on the belt pulleys of the belt drive. Another advantage is that the engine 3 Pre-assembled and testable.

In a modification of the embodiment, a receiving housing for the control electronics of the engine is also integral with the motor housing section 9 educated. This makes it possible to make the contacting of the engine not only during final assembly, but already on a pre-assembly stage. In particular, it is possible, the control electronics with the engine 3 to form a unit and then both together in the motor housing section 9 install.

By The modular structure becomes clearly defined interfaces. between the mechanical components and the installed engine as well as the associated Control device created. A large housing with a correspondingly large outer surface and few separation points allows one good heat conduction and thus a good heat dissipation from the heat-producing Components.

The handlebar 2 extends through the central portion 8th of the housing 2 through and is with a ball screw 10 coupled. This is a section of the handlebar 2 as a spindle 11 educated. This carries a ball screw nut 12 that have a bearing against the housing 2 is supported. At the ball screw nut 12 is a driven wheel 13 fixed in rotation, which is formed in the illustrated embodiment as a pulley. About a belt 14 So can the drive torque of the engine 3 over the cantilevered drive wheel 7 on the output gear 13 be transferred, causing the ball screw nut 12 is set in rotation.

Depending on the arrangement of the bearing relative to the belt drive can by the result of the drive torque of the motor 3 acting in the belt drive forces arise a tilting moment, which conventionally by the widest possible support on the ball screw nut 12 is collected, for example, by two axially spaced bearings. Here, the ball screw nut 12 opposite the handlebar 2 tilt, whereby the ease is impaired and may be generated disturbing noise emissions.

To avoid this, another concept is used according to the present invention, the main consideration is to place the storage as possible torque-free. As 1 shows is the bearing for the ball screw 10 arranged so that these are in the driven wheel 13 hineinerstreckt. Conveniently, the majority of the storage is within the driven wheel 13 arranged. However, it is also possible, the storage entirely within the driven gear 13 to arrange.

The storage is by a single rolling bearing 15 formed, which is exemplified here as a double-row deep groove ball bearings. In principle, however, other types of bearings, such as needle or roller bearings or single-row bearings can be used.

With regard to the assembly is the ball screw nut 12 designed so that both the output gear 13 as well as the rolling bearing 15 postpone on its outer circumference. In the embodiment shown here forms the ball screw nut 12 a radially projecting axial stop 16 off, against the drive wheel 13 is postponed. On the same outer circumference or on a section with a slightly smaller diameter is followed by the rolling bearing 15 pushed with its inner ring, so that the latter against a shoulder of the drive wheel 13 axially abutting.

The whole unit of ball screw nut 12 , Drive wheel 13 and rolling bearings 14 is then attached to a housing section 17 of the housing 2 attached. This housing section 17 is located on the first housing part 1a and juts out over the central section 8th out into the second housing part 1b into it. He is pot-trained. there may be a part of the pot-like housing portion 17 be excluded on the engine side to an axial mounting of the engine 3 and the partition 5 to ensure. This allows compact housing dimensions in the radial direction, as the motor 3 as close as possible to the handlebar 2 can be mounted.

During assembly, the rolling bearing 15 with its outer ring in the pot-like housing section 17 pressed. In order to damage the bearing 15 To avoid are on the output gear 13 at the height of the outer ring of the rolling bearing 15 mounting holes 18 educated. This allows the outer ring with the aid of suitable tools directly to the housing section 17 of the first housing part 1a be pressed.

In the assembled state, therefore, the storage between a shoulder of the drive wheel 13 , which bears against the inner ring of the bearing, and a shoulder of the housing portion 17 , which bears against the outer ring of the bearing, held axially.

Will the first housing part 1a made of light metal, in particular an aluminum alloy, so when using conventional bearings made of steel with regard to the different thermal expansion behavior, an additional attachment of the storage is recommended. Preferably, in this case, the outer ring of the storage by at least one additional fastening element relative to the housing portion 17 established.

In the illustrated embodiment, this is done by at least one pin 19 from the outside through the cup-shaped housing section 17 is passed. Determining the rolling bearing 15 is on the outer circumference of a groove 20 provided, in which the pin 19 engages radially. The pencil 19 For example, a conical threaded pin which is clamped with the preferably also conical groove 20 on the outer circumference of the bearing. This guarantees a play-free and safe bearing seat.

Due to the selected housing separation, the pins can 19 simply screwed in after the bearing installation. Practically all mounting hardware of the housing 1 to be attached to the first housing part, wherein the belt drive and the bearing already at a lifting of the second housing part 1b are accessible. Instead of the illustrated pin connection are also other, play-free connection techniques for mounting the storage on the housing section 17 possible.

Instead of a belt drive can in a modification of the embodiment the drive wheel and the output gear may be formed as gears, preferably comb directly with each other.

In any case, with the arrangement described above, a minimization of the tilting of the ball screw 10 and an improvement of the noise behavior. By avoiding a second bearing for catching a possible moment of transverse forces applied across the belt, the in 1 left, second housing part 1b not be edited.

One Another advantage lies in the shortening of the axial length. moreover the bearing friction remains through the use of only one bearing low and the tolerance chains shorten.

A possibly required storage protection can be carried out safely and inexpensively.

1

casing

1a

first housing part

1b

second housing part

2

handlebars

3

engine

4

motor shaft

5

partition

6

end the motor shaft

7

drive wheel (Pulley)

8th

Central section of the housing

9

Motor housing portion

10

Ball Screw

11

spindle

12

Ball screw nut

13

output gear (Pulley)

14

belt

15

roller bearing

16

head Start

17

cup-shaped housing section

18

mounting hole

19

pen

20

groove

Claims (15)

Electric power assisted vehicle steering system comprising: - a housing ( 1 ) with a handlebar ( 2 ), - an electric motor ( 3 ) for generating an auxiliary power, which laterally next to the handlebar ( 2 ), - a drive wheel ( 7 ), which by the engine ( 3 ), - a driven wheel ( 13 ), via the drive wheel ( 7 ), and - a ball screw ( 10 ), with the handlebar ( 2 ) and with the output gear ( 13 ) is rotatably connected, characterized in that the bearing for the ball screw ( 10 ) in the housing ( 1 ) extends into the driven gear or within the driven gear ( 13 ) is arranged. Vehicle steering system according to claim 1, characterized in that the major part of the bearing within the driven wheel ( 13 ) is arranged. Vehicle steering system according to claim 1 or 2, characterized in that the drive wheel ( 7 ) and the driven wheel ( 13 ) Pulleys are connected by a belt ( 14 ) are drivingly coupled together. Vehicle steering system according to claim 1 or 2, characterized that the drive wheel and the output gear are gears that mesh with each other. Vehicle steering according to one of claims 1 to 4, characterized in that the ball screw ( 10 ) a ball screw nut ( 12 ), on whose outer circumference the output gear ( 13 ) and the storage are postponed. Vehicle steering system according to one of claims 1 to 5, characterized in that the storage by a single rolling bearing ( 15 ) is formed. Vehicle steering system according to one of claims 1 to 6, characterized in that the bearing is a double row rolling bearing ( 15 ). Vehicle steering system according to one of claims 1 to 7, characterized in that in the driven wheel ( 13 ) Mounting holes ( 18 ) are formed, through which the storage with a cup-shaped housing section ( 17 ) of the housing ( 1 ) can be pressed. Vehicle steering system according to one of claims 1 to 8, characterized in that the storage in the assembled state of the housing ( 1 ) between a shoulder of the drive wheel ( 13 ), which bears against the inner ring of the bearing, and a shoulder of the cup-shaped housing portion ( 17 ) of the housing ( 1 ), which bears against the outer ring of the bearing, is held axially. Vehicle steering system according to one of claims 1 to 8, characterized in that the outer ring of the bearing by at least one additional fastening element relative to the cup-shaped housing portion ( 17 ). Vehicle steering according to one of claims 1 to 9, characterized in that the outer ring of the storage by at least one pin ( 19 ) with respect to the cup-shaped housing section ( 17 ) of the housing ( 1 ). Vehicle steering system according to claim 10, characterized in that the bearing on its outer circumference a groove ( 20 ) into which the pen ( 19 ) engages radially. A vehicle steering system according to claim 10 or 11, characterized in that the pin ( 19 ) is a conical threaded pin, with the conical groove ( 20 ) is clamped on the outer circumference of the bearing. Vehicle steering system according to one of claims 1 to 12, characterized in that the housing ( 1 ) transversely to the handlebar ( 2 ), wherein the storage on a housing part ( 1a ) is supported and the elements provided for fastening the same when lifting the other housing part ( 1b ) are accessible. Vehicle steering system according to one of claims 1 to 13, characterized in that the housing ( 1 ) is made of light metal, in particular an aluminum alloy.