DE102009000575A1 - Electric and/or electromechanical power steering system for motor vehicle, has bearing with entire circumference, supported into bearing surface of housing cover, and channel brought into housing cover and connecting two chambers together - Google Patents

Abstract

The steering system has an electric motor (5) transferring force to a recirculating ball nut (8) of a recirculating ball spindle transmission (7). The ball nut is rotatably supported in a housing unit (1) by a bearing (10) e.g. roller bearing and radial bearing. The nut and the bearing separates an interior space of the housing unit into two chambers (15, 16) along a steering rod (4) i.e. gear rod. The bearing with entire circumference is supported into a bearing surface (17) of a housing cover (3). A channel (20) is brought into the housing cover and connects the two chambers together.

Description

The The invention relates to an electric power steering system for motor vehicles with a housing unit, which at least one steering gear housing and a housing cover, wherein in the housing unit a handlebar is held axially movable, according to the Preamble of claim 1.

A generic electric power steering is from the DE 10 2006 041 720 A1 known.

The generic electric power steering has a housing unit, which through a steering gear housing and a housing cover is formed. In the housing unit a steering rod is held axially movable. The handlebar has at least a spindle portion as part of a ball nut-spindle transmission on. Axially parallel to the handlebar an electric motor is arranged, which by means of a traction mechanism a force on a ball nut of Ball Nut Spindle Transmission transmits. The Traction mechanism has in a known manner an electric motor associated drive pulley and one of the ball nut assigned Output pulley, which via a traction means, present a belt, drivingly connected together are. Due to the ball nut spindle gear, the rotational movement of the Electric motor implemented in an axial movement of the handlebar, thereby the handlebar depending on the direction of rotation of the electric motor corresponding axially in the housing unit or the steering gear housing is moved. Due to the axial displacement of the handlebar also in a known manner vehicle wheels of a motor vehicle, which with the handlebar, for example, tie rods are connected, deflected.

From Disadvantage is that through the ball nut of the interior the electromechanical steering along the handlebar in two in essential separate chambers is shared. The handlebar is usually sealed by steering cuffs to the outside. For steering movements The air moved by the steering cuffs can not or not sufficiently escape, so that in the steering unwanted Pressures arise which lead to noises and sometimes affect the feel of the steering.

The recirculating ball nut according to DE 10 2006 041 720 A1 is rotatably supported by a bearing in the steering gear housing in such a way that the bearing is not pressed over its entire circumference in the steering gear housing. This design requires a particularly stable bearing outer ring. The fact that no standard bearing outer ring can be used, the bearing is relatively expensive. Due to the interrupted bearing seat according to the DE 10 2006 041 720 A1 , ie the fact that the bearing is not pressed over its entire circumference in the steering gear housing, in the interior of the housing unit, in particular between the first and the second chamber, an air or pressure equalization possible. In addition, according to the DE 10 2006 041 720 A1 an air passage is provided which extends in a wall portion of the steering gear housing and connects the first and the second chamber with each other. The additional air duct is required due to the interrupted bearing seat only with large moving air volumes.

Of the present invention is based on the object, the disadvantages to solve the prior art, in particular an electrical To provide power steering, the best possible storage of the Bearings and an air or pressure equalization in the interior of the housing unit guaranteed.

These The object is achieved by claim 1 solved.

The inventors have recognized, on the one hand, that in order to ensure trouble-free operation of an electromechanical steering system, the air should be able to flow from one side of the recirculating ball nut to the other side during a steering movement. On the other hand, the inventors have recognized that the bearing of the ball nut in the steering gear housing, as shown in the DE 10 2006 041 720 A1 is proposed, requires a particularly stable bearing outer ring and thus is expensive.

Thereby, that now according to the invention, the camp with his entire circumference in a bearing surface of the housing cover is mounted, wherein in the housing cover at least one Channel is introduced, which the first chamber and the second chamber Connecting together, the disadvantages of the prior art solved. It is thus not a particularly stable bearing outer ring more necessary, nevertheless it is ensured that an air exchange between the two sides of the ball nut or the two axial Ends of the camp takes place.

There the bearing according to the invention completely, d. H. with its entire circumference in a storage area of the Housing cover is stored, is an air exchange without a channel inadequately possible because of greasing of bearing and recirculating ball nut a reliable Air exchange prevented.

Opposite the DE 10 2006 041 720 A1 the solution according to the invention in addition to the elimination of the stable bearing outer ring has the advantage that an introduction of the bearing in a bearing surface of the housing cover or a training of a bearing surface in the housing cover is structurally simpler and less expensive than in the steering gear transmission housing. In addition, it is structurally easier to form a channel in the housing cover which connects the first chamber to the second chamber.

From It is an advantage if the channel is cast in the housing cover is introduced, so no additional processing arises.

From It is also advantageous if the channel is in relation to Storage area or the scope of the camp only a very small or insignificant extent. This is despite ensuring the Balancing the function of the bearing and thus the function of electromechanical steering not impaired.

The Bearing, which is preferably a rolling bearing or a radial bearing, can with a conventional or standard stock outer ring provided become.

According to the invention be provided that the bearing surface interrupted by a groove is, which forms the channel or is part of the channel. A groove can be in a particularly simple manner in the storage area bring the housing cover. It is advantageous if the groove formed in a surface of the housing cover is or runs to which the camp is adjacent. It can do that suffice if the groove in a surface of the housing cover is formed, adjacent to the outer bearing ring.

The Inventors have further recognized that a channel or a groove is sufficient for pressure equalization between the two chambers. However, according to the invention can also several Be provided grooves and / or channels.

From It is advantageous if the channel is formed as a groove, which is from an inner end wall of the housing cover, which is formed as a wall portion of the first chamber, first radially to the side facing away from the steering gear housing axial End of the storage area extends and from there under Interruption of the bearing surface to the steering gear housing facing axial end of the bearing surface extends and flows into the second chamber.

Of the described course of the channel or the groove allows it, this or this form very short, so that the processing costs the housing cover is low. In addition, can the Channel or groove in this area also very easy to bring, preferably by casting or other measures known measures.

From It is an advantage if the steering gear housing has a projection, a collar or the like, which against an axial End of the camp presses or attacks there and thereby the other axial end of the bearing against a stop of the housing cover suppressed. Thus, the stock with simple measures stably fixed. Preferably, the collar, the projection or the like while at an axial end of the outer Race of the bearing, whereby the other axial end of the outer Bearing of the bearing pressed against the system of the housing cover becomes.

From It is an advantage if the collar is formed in a circular arc is and at least in the area in which a traction means of the traction mechanism between the ball nut and the drive pulley of the electric motor runs, no covenant to the camp or the outer Bearing ring adjoins. This education of the federation has different Advantages. On the one hand, it can be guaranteed that the Bund with a sufficient surface against the camp or press the outer bearing ring so that the Stable bearing is fixed. On the other hand, the federal government disturbs in that it does not run in an area in which the traction means is arranged, the connection between the drive pulley and the ball nut or its driven pulley not. Of Another remains in that the covenant only along one Arc extends, a part of the camp or the outer Raceway uncovered so that it is preferably possible in this area the channel, which is the bearing surface of the housing cover permeates, to let it flow.

advantageous Training and development of the invention will become apparent from the further dependent claims. The following is with reference to the drawing an embodiment of the invention in principle shown.

It shows:

1 a longitudinal section of the electric power steering according to the invention along the handlebar and electric motor axis; and

2 a perspective view of the inside of a housing cover.

Electric power steering systems or electromechanical steering systems with an axis-parallel drive and an electric motor, which transmits a steering assisting force by means of a transmission to a ball nut-spindle transmission, are known from the general state of the art, for example DE 10 2006 041 720 A1 , Well known, which is why below only the features essential to the invention will be discussed in more detail.

1 shows an electric power steering, especially for motor vehicles, with a hous seeinheit 1 which is a steering gear housing 2 and a housing cover 3 includes. In the housing unit 1 or substantially within the steering gear housing 2 as part of the housing unit 1 is a handlebar 4 held axially movable. The handlebar is in the embodiment as a rack 4 educated.

Parallel to the rack 4 is an electric motor 5 arranged. The rack 4 meshes with a not shown gear portion with a pinion of a steering shaft, not shown, and has an external thread on a spindle portion 6 on. The spindle section 6 the rack 4 is part of a ball nut spindle gearbox 7 ,

The spindle section 6 is engaged with a ball nut 8th , which is also part of the ball-nut spindle gearbox 7 is. The ball nut 8th is mounted axially immovable and forms with the rack 4 a motion screw. The ball nut 8th is non-rotatable with a driven pulley 9 connected and via a warehouse 10 in the housing cover 3 stored. The warehouse 10 is in the embodiment as a radial bearing 10 educated.

The electric motor 5 has a drive shaft 11 on, on a drive pulley 12 is fixed. The drive pulley 12 is smaller in diameter than the driven pulley 9 ,

One as a belt 13 trained traction means is on the driven pulley 9 and the drive pulley 12 strained and forms together with these a traction mechanism 14 , About the traction mechanism 14 becomes a force from the electric motor 5 on the ball nut 8th transfer.

The ball nut 8th and the radial bearing 10 divide the interior of the housing unit 1 along the rack 4 in a first chamber 15 and a second chamber 16 ,

The radial bearing 10 is with its entire circumference in a storage area 17 of the housing cover 3 stored. As it turned out 1 and 2 results, is the storage area 17 in the embodiment as an annular extension of the housing cover 3 educated. The radial bearing 10 is doing through a covenant 18 of the steering gear housing 2 to a plant 19 of the housing cover 3 pressed. The Bund 18 presses on an outer race 21 of the radial bearing 10 so that the outer race 21 at the plant 19 of the housing cover 3 is applied.

In the exemplary embodiment is a channel 20 in the housing cover 3 who is the first chamber 15 with the second chamber 16 connects, formed as a groove. The storage area 17 is doing through the groove 20 interrupted. The groove 20 points in relation to the storage area 17 or to the extent of the radial bearing 10 a small or insignificant extent. In the exemplary embodiment it is provided that the bearing surface 17 only through the groove 20 is interrupted.

About the groove 20 During dynamic steering operations, an air balance between the first chamber 15 and the second chamber 16 respectively.

In the exemplary embodiment is provided, the groove 20 by casting into the housing cover 3 contribute.

As can be seen from a synopsis of 1 and the 2 results, the groove runs 20 in the surfaces of the housing cover 3 to which an outer race 21 of the radial bearing 10 adjoins or abuts. The groove 20 thus extends from an inner end wall 3a of the housing cover 3 which is in contact with the first chamber 15 is, initially radial to that of the steering gear housing 2 opposite axial end of the bearing surface 17 , From there the groove extends 20 with interruption of the storage area 17 to the axial end of the bearing surface 17 which is the steering gear housing 2 is facing and which with the second chamber 16 connected is. In the exemplary embodiment, the groove extends 20 the shortest way through the storage area 17 , In this case, the groove extends 20 therefore in this area axially parallel to the rack 4 ,

The area of the inner end wall 3a in which the groove 20 extends radially corresponds in the embodiment of the system 19 ,

As can be seen from a synopsis of 1 and the 2 yields, forms the covenant 18 of the steering gear housing 2 no closed loop, but is formed only as a semicircle +/- 90 °, preferably +/- 50 °. The Bund 18 is designed and arranged such that at least in the area in which the belt 13 runs, no bunch 18 to the radial bearing 10 borders. The area in which no collar in the embodiment 18 is provided, ie the area in which the outer race 21 of the radial bearing 10 no covenant is adjacent, is in 2 provided with the reference numeral "a". In the embodiment, it is provided that the groove 20 is arranged arbitrarily in the region "a" or opens there, so that the groove 20 not from the federal government 18 of the steering gear housing 2 is covered.

1

housing unit

2

Steering gear housing

3

housing cover

3a

inner end wall

4

handlebars

5

electric motor

6

spindle section

7

Ball nut screw gear

8th

Ball nut

9

driven pulley

10

radial bearings

11

drive shaft

12

sheave

13

belt

14

traction drives

15

first chamber

16

second chamber

17

storage area

18

Federation

19

investment

20

channel

21

outer race

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 102006041720 A1 [0002, 0005, 0005, 0005, 0008, 0011, 0025]

Claims (13)

An electric power steering system for motor vehicles, comprising a housing unit comprising at least a steering gear housing and a housing cover, wherein in the housing unit a handlebar is held axially movable and the handlebar has at least one spindle portion as part of a ball nut-spindle transmission, and with an electric motor, which by means of a Zugmittelgetriebes a force on a ball nut of the ball nut-spindle transmission transmits, wherein the ball nut is rotatably supported by a bearing in the housing unit and wherein the ball nut and the bearing the interior of the housing unit along the handlebar into a first chamber and a second chamber sharing, characterized in that the bearing ( 10 ) with its entire circumference in a storage area ( 17 ) of the housing cover ( 3 ) is mounted, wherein in the housing cover ( 3 ) at least one channel ( 20 ), which is the first chamber ( 15 ) and the second chamber ( 16 ) connects to each other. Electric power steering system according to claim 1, characterized in that the bearing surface ( 17 ) is interrupted by a groove which the channel ( 20 ) or part of the channel ( 20 ). Electric power steering system according to claim 1 or 2, characterized in that the groove ( 20 ) in a surface of the housing cover ( 3 ), at which the bearing ( 10 ) is present. Electric power steering system according to claim 1, 2 or 3, characterized in that the groove ( 20 ) in a surface of the housing cover ( 3 ), at which an outer race ( 21 ) of the warehouse ( 10 ) is present. Electric power steering system according to one of claims 1 to 4, characterized in that the channel as a groove ( 20 ) formed by an inner end wall ( 3a ) of the housing cover ( 3 ), which as a wall section of the first chamber ( 15 ) is formed, initially radially to the from the steering gear housing ( 2 ) facing away from the axial end of the bearing surface and from there with interruption of the bearing surface ( 17 ) to the steering gear housing ( 2 ) facing axial end of the bearing surface ( 17 ) and into the second chamber ( 16 ) opens. Electric power steering system according to one of claims 1 to 5, characterized in that the steering gear housing ( 2 ) a projection, a collar ( 18 ) or the like, which against an axial end of the bearing ( 10 ) and thereby the other axial end of the bearing ( 10 ) against a plant ( 19 ) of the housing cover ( 3 ) presses. Electric power steering system according to claim 6, characterized in that the collar ( 18 ) at an axial end of the outer race ( 21 ) of the warehouse ( 10 ) engages and the other axial end of the outer race ( 21 ) at the plant ( 19 ) of the housing cover ( 3 ) is present. Electric power steering system according to claim 6 or 7, characterized in that the collar ( 18 ) is formed in a circular arc, so that at least in the area in which a traction means ( 13 ) of the traction mechanism ( 14 ) between the ball nut ( 8th ) and a drive shaft ( 11 ) of the electric motor ( 5 ), no covenant ( 18 ) to the warehouse ( 10 ) adjoins. Electric power steering system according to one of claims 6 to 8, characterized in that the channel ( 20 ) flows into an area (a) where no covenant ( 18 ) of the steering gear housing ( 2 ) to the warehouse ( 10 ) adjoins. Electric power steering system according to one of claims 1 to 9, characterized in that the channel ( 20 ) by casting into the housing cover ( 3 ) is introduced. Electric power steering system according to one of claims 1 to 10, characterized in that the channel ( 20 ) relative to the size of the warehouse ( 10 ) has only a small extent or width. Electric power steering system according to one of claims 1 to 11, characterized in that the bearing ( 10 ) is a rolling bearing. Electric power steering system according to one of claims 1 to 12, characterized in that the bearing ( 10 ) is a radial bearing.