DE102014014391A1 - Combined sensor concept for steering systems of motor vehicles - Google Patents

Abstract

The invention relates to an overlay plate (9) for a motor vehicle steering system, having a three-shaft transmission (22) which has an input shaft (8) and an output shaft (10) and a motor shaft (29) driven by an electric motor (20), at least the input shaft and the motor shaft or the output shaft and the motor shaft are arranged coaxially with one another, and with a sensor arrangement for detecting the angular position of the motor shaft, wherein the overlay plate comprises a sensor arrangement (42, 53) with first sensor elements (43, 54) and with second sensor elements (44, 55), and that a first transmitter element (40, 51) is provided, which is rotatable relative to the sensor arrangement (42, 53) and is in operative connection with the first sensor elements (43, 54), and wherein a second transmitter element (41, 52) which is rotatable relative to the sensor arrangement (42, 53) and is in operative connection with the second sensor elements (44, 55), wherein the first transmitter element (40, 51) or the second transmitter element (41, 52) is non-rotatably connected to the motor shaft (29), and the other of the first transmitter element (40, 51) and the second transmitter element (41, 52) is connected to the Input shaft (8) or the output shaft (10) is rotatably connected.

Description

The present invention relates to an overlay plate for a steering system of a motor vehicle having the features of the preamble of claim 1.

Superposition plates are known in power steering systems of motor vehicles. They usually have a transmission with two input shafts and an output shaft in which an input shaft is connected to the steering wheel via a steering shaft, the output shaft is connected to the pinion of a rack steering gear, and the second input shaft is connected to an electric or hydraulic drive. A particularly compact design of a superposition actuator has an arrangement in which an input shaft and the output shaft are arranged coaxially to each other, for example by one shaft in the other, designed as a hollow shaft shaft is rotatably mounted. The transmission can be a planetary gear or a wave gear in such an arrangement, so that there is a third wave for the drive in these three-axle transmissions.

The control of such a superposition actuator is to drive the drive of the superposition gearing, which acts on the second input shaft, depending on the driving situation. For example, the output shaft, an additional steering angle to be impressed when the vehicle is ranked so that the perceived by the driver overall translation of the steering is greater and the required rotation angle of the steering wheel to reach the steering stops smaller. It can also be provided to provide a crosswind compensation, in which the driver drives with the steering wheel in the straight ahead position and the additional steering angle required to compensate for the side wind is impressed in the manner of a lead angle of the actuator of the overlay actuator. Thus, it is possible that the rotational speed and / or the rotational directions of the first input shaft and the second input shaft differ from each other. Other applications include lane departure warning, autonomous driving and ESP systems.

For all these applications it is necessary that the control is always informed about the position of the respective shafts of the superposition gear. For this purpose, known superposition gear such. B. the overlay plate from the published patent application DE 10 2007 000 945 A1 an internal sensor detecting either the rotational angular position of one of the shafts or the rotational angular position of the electric motor. In the second case, these sensors are called rotor position sensors. The current angle of rotation of the input shaft connected to the steering wheel is not detected in known overlay plates. Here, the steering angle signal of an otherwise present in the motor vehicle steering wheel angle sensor is used. Such a steering wheel angle sensor can for example be assigned directly to the steering shaft in the region of the steering wheel or the steering column.

The overlay plate always requires in the known embodiments, such as in the above-mentioned publication, an external sensor signal and the associated data transmission, which supplies the signal to the controller of the overlay controller.

The object of the invention is to provide an improved sensor concept for a steering system, which has a simple structure and requires a small installation space.

The object is achieved by a device having the features of claim 1. Advantageous developments of the invention are shown in the subclaims. Because the overlay plate for a motor vehicle steering system, having a three-shaft gearbox having an input shaft and an output shaft and a motor shaft driven by an electric motor, wherein at least the input shaft and the motor shaft or the output shaft and the motor shaft are arranged coaxially to each other, and with a sensor arrangement for detection the angular position of the motor shaft, wherein the overlay plate has a sensor arrangement with first sensor elements and with second sensor elements, and that a first encoder element is provided, which is rotatable relative to the sensor arrangement and is in operative connection with the first sensor elements, and wherein a second encoder element is provided, which is rotatable relative to the sensor arrangement and is in operative connection with the second sensor elements, wherein the first donor element or the second donor element is rotatably connected to the motor shaft, and the respective other of the first Encoder element and the second encoder element is rotatably connected to the input shaft or the output shaft, a compact device can be presented with an improved sensor concept.

Advantageously, the transmitter element is rotatably connected to the input shaft and a steering wheel.

It is preferable that the sensor arrangement has, as first sensor elements and second sensor elements, in each case a transmitter and receiver coil arranged in the circumferential direction of the sensor arrangement and facing the first transmitter element or the second transmitter element. As a result, a particularly compact design is achieved.

To display a scan of the steering wheel angle even with multiple revolutions is advantageously carried out the sensor arrangement in combination with the encoder connected to the input shaft donor element for detecting the steering wheel angle as a multi-turn sensor. A multi-turn sensor can detect several full revolutions, ie rotation angles of more than 360 °. In this case, a memory element can be provided that counts the number of passes and adds the offset of the complete revolutions to the angle value within one rotation.

To increase the accuracy of two transmitter and receiver coils may be present for each donor element in the sensor array.

A particularly compact design is achieved when the sensor arrangement is arranged between the electric motor and the transmission. In this case, the sensor arrangement is advantageously arranged in a space of a motor housing.

In particular for representing a measurement of the differential angle between the input shaft and the output shaft, the sensor arrangement in combination with the encoder element connected to the motor shaft for detecting the rotor angle can be designed as a multi-turn sensor.

In particular, the sensor arrangement of the overlay actuator is adapted to output the difference angle between the rotational position of the output shaft and the input shaft as a measured value.

• a) zwei Zähleinheiten umfasst, die die Umdrehungszahl der Eingangswelle und der Motorwelle zählen,
• b) eine Speichereinheit umfasst, die die Anzahl der Umdrehungen der Eingangswelle und der Motorwelle speichert,
• c) eine Recheneinheit, die aus den aktuell gemessenen Drehwinkeln der Eingangswelle und der Motorwelle unter Zuhilfenahme der abgespeicherten Umdrehungszahlen den absoluten Drehwinkel der Eingangswelle und der Motorwelle bestimmt.

Advantageously, the sensor arrangement of the overlay actuator may further comprise the following elements:

• a) comprises two counting units which count the number of revolutions of the input shaft and the motor shaft,
• b) comprises a memory unit which stores the number of revolutions of the input shaft and the motor shaft,
• c) an arithmetic unit which determines the absolute rotation angle of the input shaft and the motor shaft from the currently measured rotation angles of the input shaft and the motor shaft with the aid of the stored revolution numbers.

With this design, the control of the steering system is much easier.

Advantage of this solution is the small space, since two rotational movements can be detected with a control unit.

Hereinafter, the present invention will be described in two embodiments with reference to the drawings. Show it:

1 : an electromechanical motor vehicle steering system with a superposition plate in a schematic representation;

2 a superimposed plate according to a first embodiment in a perspective view;

3 : the overlay plate off 2 in a longitudinal section;

4 : the overlay plate off 2 in a perspective exploded view;

5 : the overlay plate off 2 in a further perspective exploded view; such as

6 : a superposition plate according to a second embodiment in a longitudinal section similar 3 ,

In the 1 is an electromechanical steering system for a motor vehicle shown schematically. The steering has a steering wheel in a known manner 1 on that is to be operated by the driver. The steering wheel 1 is with a steering shaft 2 rotatably connected, in an on-board adjustable steering column 3 is beset rotatably. The steering shaft 2 is with two joints 4 and 5 provided, which allow pivoting of the steering shaft. This will be an upper steering shaft 6 , a middle steering shaft 7 and a lower steering shaft 8th educated. The upper steering shaft 6 is the input shaft of a superposition actuator 9 , which is shown here only schematically. The overlay plate 9 finally acts with its output shaft, with the interposition of the lower steering shaft 8th and the two joints 4 and 5 on a pinion 10 which with a rack 11 combs. A turn of the steering wheel 1 thus leads by rotation of the steering shaft 2 and the pinion 10 to a displacement of the rack 11 in the transverse direction of the vehicle. The rack 11 carries tie rods 12 , in turn, with steerable vehicle wheels 13 are connected. In this way causes a rotation of the steering wheel 1 a pivoting of the steerable vehicle wheels 13 , The overlay plate 9 can, with appropriate control, a rotational angle or a rotational angular velocity to the pinion shaft 10 add, so compared to that of the steering wheel 1 predetermined position, a larger or smaller pivoting of the steered wheels 13 make. In the example shown is an electric power assist 100 provided additionally supports the steering movement and relieves the driver in his steering work. This is off known in the art and will not be discussed further here.

There are also known applications in which the overlay plate in the device 9a between the lower steering shaft 8th and the steering pinion 10 is arranged, with even the steering pinion 10 can be coupled directly to the output shaft of the overlay actuator or formed in one piece. There are also known applications where the device 9a is designed as an electrical auxiliary power device to relieve the driver in the steering work.

However, it is important that for a safe and comfortable operation of the overlay 9 both a rotor position sensor of the electric motor included in the overlay actuator 9 is integrated, as well as a steering wheel angle sensor for the angular position of the steering wheel 1 required are.

Based on this angle information, as well as other information, an ECU 101 (= electronic control unit) the electric motor 20 of the overlay folder 9 control so that the desired angle superposition of the steering movement is achieved.

The integration of these two sensors in the structural unit of the overlay actuator 9 will be further described below.

The 2 shows a overlay plate 9 in a perspective view. The overlay plate 9 has an electric motor 20 on, with connection cables 102 via an electrical connection 21 with the ECU 101 is coupled. The electric motor 20 is with a gearbox 22 connected to a transmission input shaft 18 wearing. To the input shaft 18 can the steering shaft 2 out 1 be connected. Between the engine 20 and the transmission 22 is a circuit board 23 arranged in a space between a motor housing 25 and a ring gear 26 of the planetary gear designed as a transmission 22 is arranged.

The exact relative arrangement of the various components to each other will be described below with reference to 3 described in more detail the overlay plate 9 out 2 in a schematic longitudinal section shows.

The overlay plate 9 indicates the electric motor 20 with the motor housing 25 in which a stator 27 tight and a rotor 28 are rotatably arranged. The rotor 28 drives a hollow shaft 29 as a motor shaft. The hollow shaft 29 is in rolling bearings 30 rotatably in the motor housing 25 stored.

The hollow shaft 29 sticks out in the 3 shown on the left side, into the planetary gear in and carries there at a free end a sun gear 31 , The sun wheel 31 in his turn he pinches planet wheels 32 coming from a planet carrier 33 be held and guided. Outside surrounds the ring gear 26 the planetary gears and mesh with them. The ring gear 26 is cup-shaped and carries in its axis of rotation a free stub shaft 34 which can be used as input or output shaft of the planetary gear.

The planet carrier 33 turn is with a wave 35 connected coaxially to the stub shaft 34 is aligned and through the hollow shaft 29 through the electric motor 20 runs and on the gear 22 opposite side of the motor housing 25 from the motor housing 25 exit. At this point is the wave 35 in a rolling bearing 36 in the motor housing 25 rotatably mounted. The wave 35 , the shaft stump 34 and the hollow shaft 29 are thus against each other and over the planetary gear or three-shaft gear 22 coupled together.

The rotation of the stub shaft 34 and thus forcibly coupled ring gear 26 should be recorded for the control as well as the rotational movement of the hollow shaft 29 , This is a first encoder disc 40 inside the open, the engine 20 facing edge of the ring gear 26 arranged. A second encoder disc 41 is non-rotatable with the hollow shaft 29 connected and facing radially outward from the shaft 29 path. The axial position of the second encoder disc 41 with respect to the hollow shaft 29 agrees with the axial position of the first encoder shaft 40 in the arrangement. The two encoder discs 40 and 41 rotate in operation in the same plane and have a defined axial distance to the board 23 on.

The motor housing 25 finally carries a sensor array 42 with first sensor elements 43 and second sensor elements 44 in which the sensor arrangement forms an integral part of the circuit board 23 represents. The first sensor elements 43 lie with the interposition of an air gap of the first encoder disc 40 directly opposite, wherein the air gap defines an axial distance. The second sensor elements 44 are also at an axial distance of the second encoder disc 41 across from.

When in operation by driving the electric motor 20 the motor shaft 29 in rotation with respect to the motor housing 25 is offset, so moves the second encoder disc 41 opposite to the second sensor elements 44 , which is converted with a suitable sensor known per se into a rotational angle signal and as a rotor position signal can be evaluated. If further the stub shaft 34 and the ring gear 26 opposite the motor housing 25 be turned, then strokes the first encoder disc 40 at the first sensor elements 43 over and generates a corresponding signal, which can be evaluated as an angle signal (incremental or absolute). Depending on whether the stub shaft 34 with the steering wheel 1 or with the pinion 10 the steering is connected, this angle signal represents a different physical quantity. Is the stub shaft 34 connected to the steering wheel, then the second signal gives the steering wheel angle signal. Is the stub shaft 34 with the pinion 10 connected, then the angle signal represents a steering angle.

Overall, this structure results in a very compact arrangement, with the inside of the structural unit of the overlay actuator 9 generates two rotational angle signals and from a common sensor arrangement 42 can be detected and optionally also evaluated, whereby it is possible to determine from the two rotation angle signals, the rotation angle of not equipped with a rotation angle sensor shaft. For the desired, reliable and comfortable control of the overlay actuator, no external transmission of angle signals is required.

The 4 shows the overlay plate 9 out 2 in a first exploded view. The same components bear the same reference numbers.

In this illustration, it can be seen that the board 23 the first donor element 40 and the second donor element 41 surrounds so that the two donor elements lie approximately in a plane. The motor 20 and the gearbox 22 are separated from each other in this illustration.

The 5 shows a further illustration accordingly 4 , wherein the first donor element 40 and the second donor element 41 from the motor housing 25 are shown separately. In this illustration, it can be seen that the first donor element 40 a relatively narrow, large diameter ring with inward facing sectors, while the second donor element 41 is a smaller diameter ring with outwardly facing sectors. The in the presentation of the 4 unrecognizable sensor elements, the first sensor elements 43 and the second sensor elements 44 , are visible here. The first sensor elements 43 are ring-shaped on the board 23 coaxial with the hollow shaft 29 arranged and fit from the diameter to the first donor element 40 , The second sensor elements 44 are coaxially within the first sensor elements 43 and are in diameter to match the second donor element disposed above 41 educated. The sensor elements 43 . 44 are shown schematically and each consist of a transmitter coil and a receiver coil. In operation, the inwardly facing sectors of the first donor element sweep 40 the first sensor elements 43 and generate an evaluable signal there. Accordingly, the outwardly facing sectors of the second donor element sweep 41 the second sensor elements 44 and also generate an evaluable signal there. The donor elements 40 . 41 consist of a ferromagnetic material or in other words a steel sheet. The arrangement is due to the location within the overlay actuator 9 well protected against external influences.

The 6 finally shows a structure similar to that in 3 displayed overlay plate. Here, however, the angle sensor is not arranged between the engine and the transmission, but on the transmission far side of the engine. In detail, the shows 6 the mechanical structure 3 , Some reference numerals have been omitted for clarity. Like reference numerals designate like components.

In this embodiment is within the motor housing 25 a room 50 provided for the sensors, so that these protected within the motor housing 25 can be arranged. The sensor system comprises a first transmitter element 51 in the form of a disc-shaped donor element that rotates with the in the room 50 end stub shaft of the hollow shaft 29 , which is also the motor shaft, is attached. A second donor element 52 is also in the form of a disk rotatably on the shaft 35 attached. Between the first donor element 51 and the second donor element 52 a distance is provided. At this distance is a control and sensor unit 53 arranged with their outside on the inner peripheral wall of the room 50 is attached. The sensor arrangement 53 includes first sensors 54 and second sensors 55 , The first sensors 54 are on the sensor array 53 arranged so that they are the outer edge region of the first donor element 51 immediately opposite. The second sensor elements 55 are arranged so that they are on the sensor assembly 53 the edge region of the second donor element 52 immediately opposite. The first sensor 54 is on the one side of the sensor array 53 and the second sensor 55 on the other flat side of the sensor arrangement 53 arranged or in other words are the sensors 54 . 55 arranged facing away from each other. Upon rotation of the motor shaft or hollow shaft 29 the first encoder element turns 51 with and generated in the first sensor elements 54 a corresponding evaluable signal from the sensor unit 53 and, where appropriate, to the ECU 101 , for example via control lines 103 , is forwarded. Accordingly, upon rotation of the shaft 35 the second donor element 52 relative to the second Senor elements 55 moved, so that there are also scannable signals from the sensor unit 53 and the controller 51 are evaluable. Also in this embodiment is therefore within the overlay actuator 9 the detection and evaluation of rotation angles or rotational positions of two waves inde pendent of each other possible. In addition, in accordance with this arrangement 6 the sensors by housing in the room 50 very well protected.

Where applicable, all individual features illustrated in the individual embodiments may be combined and / or interchanged without departing from the scope of the invention.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102007000945 A1 [0004]

Claims (10)

Overlay ( 9 ) for a motor vehicle steering, with a three-shaft transmission ( 22 ), which has an input shaft ( 18 ) and an output shaft ( 10 ) and one of an electric motor ( 20 ) driven motor shaft ( 29 ), wherein at least the input shaft and the motor shaft or the output shaft and the motor shaft are arranged coaxially to one another, and with a sensor arrangement for detecting the angular position of the motor shaft, characterized in that the overlay plate a sensor arrangement ( 42 . 53 ) with first sensor elements ( 43 . 54 ) and with second sensor elements ( 44 . 55 ), and that a first donor element ( 40 . 51 ), which is opposite the sensor arrangement ( 42 . 53 ) is rotatable and with the first sensor elements ( 43 . 54 ) is in operative connection, and that a second donor element ( 41 . 52 ), which is opposite the sensor arrangement ( 42 . 53 ) is rotatable and with the second sensor elements ( 44 . 55 ) is in operative connection, wherein the first donor element ( 40 . 51 ) or the second encoder element ( 41 . 52 ) with the motor shaft ( 29 ) is rotatably connected, and the other of the first donor element ( 40 . 51 ) and the second donor element ( 41 . 52 ) with the input shaft ( 8th ) or the output shaft ( 10 ) is rotatably connected. Superposition plate according to claim 1, characterized in that the encoder element with the input shaft ( 18 ) and with a steering wheel ( 1 (rotatably connected. Superposition plate according to one of the preceding claims, characterized in that the sensor arrangement ( 42 . 53 ) as first sensor elements ( 43 . 54 ) and second sensor elements ( 44 . 55 ) each arranged in the circumferential direction of the sensor arrangement, the first donor element ( 40 . 51 ) or the second donor element ( 41 . 52 ) facing transmitter and receiver coil. Superposition plate according to one of the preceding claims, characterized in that the sensor arrangement ( 42 . 53 ) in combination with that with the input shaft ( 18 ) connected encoder element for detecting the steering wheel angle are designed as a multi-turn sensor. Overlay actuator according to one of the preceding claims, characterized in that two transmitter and receiver coils are provided for each transmitter element in the sensor arrangement. Superposition plate according to one of the preceding claims, characterized in that the sensor arrangement ( 42 . 53 ) between the electric motor ( 20 ) and the transmission ( 22 ) is arranged. Superposition plate according to one of the preceding claims, characterized in that the sensor arrangement ( 42 . 53 ) in a room ( 50 ) of a motor housing ( 25 ) is arranged. Superposition plate according to one of the preceding claims, characterized in that the sensor arrangement ( 42 . 53 ) in combination with the one with the motor shaft ( 29 ) connected encoder element for detecting the rotor angle are designed as a multi-turn sensor. Superposition plate according to one of the preceding claims, characterized in that the sensor arrangement ( 42 . 53 ) is adapted to the difference angle between the rotational position of the output shaft ( 35 ) and the input shaft ( 18 ) as a measured value. Superposition plate according to one of the preceding claims, characterized in that the sensor arrangement ( 42 . 53 ) further comprises the following elements: a) comprises two counting units which determine the number of revolutions of the input shaft ( 18 ) and the motor shaft ( 29 b) comprises a memory unit which determines the number of revolutions of the input shaft ( 18 ) and the motor shaft ( 29 ), c) an arithmetic unit, which from the currently measured rotation angles of the input shaft ( 18 ) and the motor shaft ( 29 ) with the aid of the stored revolution numbers the absolute rotation angle of the input shaft ( 18 ) and the motor shaft ( 29 ) certainly.

Images