DE10032671A1 - Power steering system for motor vehicle has parallel plates on steering shaft sections with code tracks and code markings whose images are formed on photosensitive array - Google Patents

Abstract

The system has a detector of torque exerted by the driver on the steering wheel with a torsion module (5) in the steering spindle (1) and optoelectronic relative motion detectors with a sensor plate (8) fixed to one steering spindle section (3) and second sensor plate (9) fixed to a second spindle section (2). The plates are parallel and have code tracks with code markings whose images are formed on a photosensitive array (13).

Description

The invention relates to a power steering system for motor vehicles ge with a torque detection device for detecting the a driver exercised during a steering movement of the steering wheel Torque, comprising a in an interface of the steering shaft orderly torsion module as well as receiving means for receiving the Relative movement of the two ge by the torsion module separated steering spindle sections from each other during a steering movement.

Motor vehicles are often equipped with an electronic stability pro grams (ESP system) and an electrical steering support (EPS System). To provide for an electric steering force The steering spindle is divided into two parts built, with both steering spindle parts together by a torsion module who are connected. One steering spindle section is an absolute one measuring angle detection unit and the other steering spindle cut is the angular misalignment caused by the torsion module receiving relative measuring angle detection unit assigned. at de Angle detection units are available for evaluating the recorded data a processor unit connected. That from a vehicle driver exerted via the steering wheel on the upper steering spindle section Torque is directly through the relatively measuring angle detection unit given. Depending on the torque applied and the  The electrical steering force is then activated support device. Such a power steering system is described for example in DE 197 55 044 C1.

This known steering force support device is capable of to deliver the desired and required characteristic data, but this must be a set torsion module be designed such that even with one small applied torque a relative movement between the steering-wheel-side steering spindle section and the steering-side spin del section has taken place, the amount of movement being relative movement must be large enough for it to be removed from the receiving means, that were previously addressed as angle detection units, he can be grasped. The torsion module must therefore be made relatively soft det be, so that the driver sometimes a spongy steering pressure. Instead of using a relatively soft one Torsion module it would be desirable to have a correspondingly harder one to be able to use it.

The invention lies on the basis of this prior art discussed hence on the one hand the task of a steering power support system stem for motor vehicles of the type mentioned in this way form that the torsion module used to avoid a spongy steering impression can be relatively hard.

This object is achieved in that the Aufnah Memittel are designed optoelectronic working and a Wegmeßein direction with one of the steering wheel side of the interface and First encoder connected in a rotationally fixed manner to this steering spindle section disc and with another, in one to the level of the first donor disc arranged parallel plane and the steering side of the Interface assigned and non-rotatable with this steering spindle section connected second encoder disc, each one of the two randli Chen limits one by the stacking of the two Encoder disks define code track by one of each encoder disk-associated coding is formed and by the coding against the encoder discs formed code track limits at a re relative movement of the two encoder disks to each other their position the change, as well as with a fixed to the encoder disks  Neten photosensitive sensor device consisting of a sensor ray with an extension transverse to the direction of movement of the encoder disks and a lighting device for optically imaging the through the Coding of the encoder disks formed on the photosen code track sitive surface of the sensor array.

In the steering power support system according to the invention is one second encoder disk is provided, which is parallel to its plane first encoder disk is arranged. Therefore, the Coding of a second encoder disc also on the photosensitive Surface of the sensor array so that the result is on the sensor array the codes of both encoder disks are shown superimposed on the same side become. The coding of the two encoder disks is such formed that this is a code track imaged on the sensor array define. There is a boundary of the code track formed by coding an encoder disc. By the arrangement of the two encoder disks, these are relatively movable relative to one another mechanically coupled to each other via the torsion module. When opening gene torque, for example in a steering wheel rotation The two encoder disks will turn right due to the torsion module moved relatively to each other so that the code track boundaries of the two Due to this movement, encoder disks change their position relative to one another countries. This change in the configuration of the code track is with the Sen sorarray, since different areas are each exposed, detectable. Such a change in the configuration of the code track is optoelectro nically detectable with a much higher resolution, compare with an absolute angle detection. For this reason, at such a steering power support system a much harder Formed torsion module are used so that the resulting Steering impression can correspond to that of direct steering.

To implement the steering force support system according to the invention stems, it is sufficient to use a line sensor as a sensor array, which is arranged in the transverse direction to the course of the code track. In one In such a case, it is appropriate to code the encoder disks in this way to design that with a relative movement of the two donors ben to each other the width of the ge by the code track boundaries formed code track changes.  

In a preferred embodiment, the code track limits are used tongues of the encoder disk also formed a Lenkwin detection, so that when the steering spindle rotates, the code track is successively mapped to other areas of the sensor array. Such an embodiment is useful because in numerous motor vehicles In addition to a steering power support system, Lenkwin also testify kelsensoren be used and in this embodiment both Ele elements are provided by a module. In this embodiment, egg ne change of the steering angle by shifting the code track formation detectable on the sensor array. It can be a steering angle determination by detecting the position of the code track limitation of those gen encoder disk, which is arranged on the steering wheel side. A change tion of the width of the code track resulting from a relative movement of the two encoder disks to each other indicates that a torque at for example on the steering wheel. Depending on whether starting from a predefined width of the code track as the zero position ver widens or whether the width starts from this zero position wrestles, can be closed on the direction of the applied torque will be. The coding of the two encoder disks can, for example serve an Archimedean spiral, with the two in the zero position Encoder disks are arranged so that they are offset from one another also results in a code track designed as an Archimedean spiral.

The invention will now be described with reference to the accompanying Figures described using an exemplary embodiment. Show it:

Fig. 1 is a schematic, partially sectioned side view of the upper portion of a steering shaft of a motor vehicle having a torque detection device for a specific electrical power assistance,

FIG. 2a, b, respectively a plan view of an encoder disc of the Drehmo ment detector of FIG. 1,

Fig. 3a, b is a plan view of the superimposed encoder disks ben Fig. 2a and b to form a code track oh ne an applied torque in each under a different steering position and

Fig. 4a, b the arrangement of Fig. 3 at an applied in one direction each torque.

A steering spindle 1 of a motor vehicle, not shown, is formed in two parts in its upper region and comprises a steering-spindle section 2 on the steering side and a steering-wheel-side section 3 . At the free end of the steering spindle section 3 , a steering wheel 4 is mounted. The steering spindle sections 2 and 3 are connected to one another by a torsion module 5 . The torsion module 5 is part of a torque detection device 6 , which is used in the context of an electronic steering power support system (EPS system). Via the EPS system, which is shown schematically in FIG. 1 and is given the reference symbol 7 , electrical support is provided for the torque exerted by a driver via the steering wheel 4 on the steering spindle 1 .

The torque detection device 6 further comprises two encoder discs ben 8 , 9 , which carry a coding formed transparently. In the illustrated embodiment, the two encoder disks 8 , 9 are formed identically and arranged in their arrangement in the torque detection device 6 offset from one another by an angle of rotation. The encoder disk 8 is rotatably connected to the steering spindle section 3 and the Ge bersscheibe 9 in turn connected to the steering spindle section 2 . Thus, the encoder disc 9 zoom ranges close as possible to the encoder disc 8, this delabschnitt to the steering spinning a cup-shaped holder 10 is attached. 2 The torsion module 5 is quasi radially enclosed by the holder 10 . The torque detection device 6 is also a sensor device 11 associated consisting of a lighting device 12 and a line sensor 13 , the longitudinal extension ra dial to the steering shaft 1 is arranged. The lighting device 12 illuminates the undersides of the two sensor disks 8 , 9 , so that their codes are imaged on the photosensitive surface of the line sensor 13 .

Separated by the torsion module 5 between the two Lenkspin delabschnitte 2 , 3, a relative movement is possible if, for example, a torque is exerted on the steering spindle section 3 by a driver via the steering wheel 4 .

The output of the line sensor 13 acts on a microcontroller 14 for evaluating the output data of the individual converter elements for torque detection. Depending on the detected torque, the EPS system 7 is activated by the microcontroller 14 to provide the respective steering assistance.

In FIGS. 2a and b are the two transducer disks 8, 9 shown in a plan view, wherein the sensor disk 8 in Fig. 2a and the encoder disk in Fig. 9 is shown 2b. Basically, the two encoder disks 8 , 9 are constructed identically and each have an Archimedean spiral S as coding, which is transparent for example in the embodiment shown. The other areas of the encoder disks 8 , 9 are - as indicated by the hatching in each case - opaque. In their intended arrangement one above the other within the torque detection device 6 , a code track C is formed by the two codings S. The code track C also represented an archimedical spiral. This arrangement of the two encoder disks 8 , 9 of the torque detection device 6 is shown in FIG. 3a in a straight alignment of the wheels. The line sensor 13 is indicated schematically behind the encoder disk 8 , on which the code track C is shown in a certain area of the line sensor 13 . The code track C is formed by the simultaneous mapping of the Archimedean spirals of the two encoder disks 8 , 9 by a border R ₁ , R _{2 of} the Archimedean spiral S of the transmission disc 8 and 9 , also referred to as code trace limitation. The width of the code track C is constant over its effective extent.

The code track C designed as an Archimedean spiral serves for a steering angle detection, with different sections of the photosensitive surface of the line sensor 13 being exposed by the code track C at different steering wheel positions. For example, in FIG. 3b a steering wheel position deviating from the straight-ahead position of the wheels is given, in which the two sensor disks 8 , 9 have been moved relative to the lens sensor 13 in accordance with the arrow direction shown in FIG. 3b. The position of the code track C in relation to the width of the sensor line 13 can be determined on the basis of the position of the edge R ₁ of the sensor disc 8 assigned to the steering wheel 4 .

Since the two encoder disks 8 , 9 can be rotated relative to one another by the torsion module 5 in the event of a torque acting on the steering wheel 4 (steering torque), the width of the code track C changes both as a function of the applied steering torque and as a function of the Direction of the steering torque. In Fig. 4a, the arrangement of the transducer disks 8 shown in FIG. 3, 9 indicated a acting in one direction, steering torque at concern. When a steering torque is applied in this direction, the width of the code track C is increased. The width of the code track C can thus serve as a measure of the torque applied, the direction of the applied steering torque resulting from an increase or decrease in the code track C with respect to the width of the code track C when no steering torque is present - as in FIGS FIGS. 3a and 3b - is determined. Since the edge R _{1 of} the coding S of the encoder disc 8 is relevant for the determination of the steering angle, an increase or decrease in the width of the code track is not noticeable in a determination of the steering angle, since the edge R _{2 of} the steering wheel-side encoder disc 9 in Depending on the applied torque is moved relative to the edge R ₁ . By forming the center of gravity of the exposed areas of the sensor line 13 for steering angle detection, such a change in the width of the code track C does not affect it. FIG. 4b shows an example of the two transducer disks 8, 9 has been reduced with an applied steering torque in the other direction, whereby the width of the code track C.

From the description of the invention it is clear that with the described benen torque detection device not only the necessary Da for steering power assistance in a high resolution, but also determines the data relevant for steering angle detection can be, in a clever way a combination of the encoder elements providing the respective information is.  

Compilation of the reference symbols

1

steering shaft

2

Steering shaft section

3

Steering shaft section

4

steering wheel

5

torsion

6

Torque detector

7

EPS system

8th

sensor disk

9

sensor disk

10

holder

11

sensor device

12

lighting device

13

line sensor

14

microcontroller
C code track
R _{1, 2}

edge
S Archimedean spiral

Claims (5)

1. Steering force support system for motor vehicles with a torque detection device ( 6 ) for detecting the torque exerted by a driver during a steering movement of the steering wheel ( 4 ), comprising a torsion module ( 5 ) arranged in an interface of the steering spindle ( 1 ) and receiving means for receiving the relative movement of the two by the torsion onsmodul ( 5 ) separate steering spindle sections ( 2 , 3 ) to each other during a steering movement, characterized in that the receiving means are designed to work optoelectronically and a displacement measuring device with one of the steering wheel side of the interface and rotatably associated with this steering spindle del section ( 3 ) connected first encoder disc ( 8 ) and with another, arranged in a plane parallel to the plane of the first encoder disc ( 8 ) and parallel to the steering side of the interface and rotatably connected to this steering spindle section ( 2 ) connected to the second encoder disc ( 9 ), one of the two marginal boundaries (R ₁ , R ₂ ) of a code track (C) defined by the mutual arrangement of the two encoder disks ( 8 , 9 ) by a respective code (S) assigned to an encoder disk ( 8 , 9 ) is formed and the code track limits (R ₁ , R ₂ ) formed by the encodings of the encoder disks ( 8 , 9 ) change their position relative to one another when the two encoder disks ( 8 , 9 ) move relative to one another, as well as with one of the encoder disks ( 8 , 9 ) Stationarily arranged photosensitive sensor device ( 11 ) consisting of a sensor array ( 13 ) with an extension transversely to the direction of movement of the encoder disks ( 8 , 9 ) and an illumination device ( 12 ) for optical imaging of the codes (S) of the encoder disks ( 8 , 9 ) formed code track (C) on the photosensitive surface of the sensor array ( 13 ). 2. Steering force support system according to claim 1, characterized in that the codes (S) of the encoder disks ( 8 , 9 ) are designed to form the code track (C) such that with a relative movement of the two encoder disks ( 8 , 9 ) to each other the width of the code track (C ₁ ) formed by the code track boundaries (R ₁ , R ₂ ) changes. 3. Steering force support system according to claim 1 or 2, characterized in that the discs ( 8 , 9 ) formed by the codes (S) of the encoder discs (C) is successively shown on a different movement of the steering wheel on different areas of the sensor array ( 13 ). 4. Steering force support system according to claim 3, characterized ge indicates that the code track (C) in the manner of an archimedi is formed spiral. 5. Steering force support system according to one of claims 1 to 4, characterized in that one of the two encoder disks ( 9 ) via a pot-shaped holder ( 10 ), the torsion module ( 5 ) radially including with this encoder disk ( 9 ) assigned steering spindle section ( 2nd ) connected is.