DE19935283A1 - Electrically aided auxiliary power steering for fitting to motor vehicles has an incoming shaft to transfer steering torque required for steering a vehicle's wheels and an electrical motor supplying auxiliary power. - Google Patents

Abstract

An incoming shaft (6) operating with a steering hand wheel transfers steering torque required for steering a vehicle's wheels operating with an outgoing section (2) connected to the incoming shaft by a torsionally elastic element (5). An electrical motor supplying direct or indirect auxiliary power to the outgoing section fits on the auxiliary power steering.

Description

The invention relates to an electrically assisted Power steering for motor vehicles according to the generic term of claim 1. The power steering includes an on gear shaft in operative connection with a steering handwheel stands for the transmission of one for the steering of steering wheels required torque. On The output link is in active connection with the wheels to be steered binding. A servo motor, through which directly or indirectly an assistant can be exercised on the output member, is located on the power steering. The input shaft and the output member are via a torsionally elastic member connected in such a way that between the input wel le and the output member a limited twisting movement is possible. For contactless detection of the direction and the strength of a steering acting on the input shaft torque and other steering-specific parameters serves a non-contact registration unit. The Erfas solution unit comprises at least one with the input shaft or the output member connected sensor.

Such power steering is known from the DE 38 44 578 C2. This power steering system consists of a Torque meter, which is a contactless torque sensor to determine a longitudinally transmitted to the steering shaft Torque, an electronic control for that on the Steering shaft additional torque to be transmitted and a Ser vomotor has. The torque meter also includes Drive shaft, clutch bearing and evaluation device too a magnetic sensor device consisting of two drums  with magnetizable surfaces and with an on gear or are connected to an output member.

The drums are on their circumference or on their forehead che provided with magnetizable media such that they alternately form magnetic north and south poles. By Measure the difference in the angle of rotation of the two drums is using magnetoresistive elements Torque detected.

This arrangement requires a clock spring or a Grinder unit for the electrical connection of the rotating drums.

When using a clock spring for electrical Connection of several cables with a length of up to 2 m compelled. Electromagnetic Interferences have a negative impact on the measurement signals. In addition These long cable connections pose risks in terms of Cable and solder joint break.

Instead of a clock spring, a grinder unit for used the electrical connection, so here it can Transition area between grinder and contact surface Factors such as wear, corrosion and dirt deposits to inaccurate measurement results.

In addition, when installed in the motor vehicle Grinder unit and clock spring through oil, dirt and Fat deposits for malfunctions and inaccurate measurement results nits come.

The present invention is based on the object an electrically assisted power steering system for power vehicles depict the steering-specific parameters without additional electrical connection units  can. In particular, the assembly effort and the susceptibility to failure can be reduced.

The object underlying the invention is achieved by one, also the characteristic features of the main claim having generic, electrically assisted auxiliary Power steering for motor vehicles solved.

The solution is particularly in that the Ver angle of rotation between input and output link not di is measured directly, but using a backlash-free Ge drive in a longitudinal movement proportional to the angle of rotation is converted. This longitudinal movement is a measure of the applied torque and is on a, at least egg ring with a north and at least one south pole shaped element transferred. In the transition area between The north and south poles must ensure that the out direction exactly perpendicular to an axis of the annular Element is done in order to achieve exact measurement results. Furthermore, it is for a high accuracy of the measurement result se required to design the gearbox so that the ring shaped element just a longitudinal movement along a vorbe aligned axis can perform. This longitudinal movement is from a magnetoresistive sensor recorded to the elec tronic unit forwarded and processed there.

There are different types of gears for these requirements suitable, but the use is particularly advantageous of elastic joint gears and screw gears.

The electronics unit can expediently be used for the Er summarize the steering-specific parameters torque and Steering direction summarized in a single component the. This in turn results in little assembly effort.  

By using an electric motor as a Servomo The measured parameters can be used to control the Engine speed can be used in a simple manner and thus lead to improved control behavior.

Advantageous and expedient embodiments of the Er invention are specified in the subclaims. The Erfin but is not on the combinations of features of the application limited sayings, rather arise for the expert further useful combinations of requirements and individual claim characteristics from the task.

Below are different based on the drawings Embodiments of the present invention in principle as described.

Show it:

Fig. 1 shows a first embodiment of an elec trically assisted power steering system for motor vehicles using the example of a toothed rack gene steering with a gear of the screw gear type;

Fig. 2 shows a second embodiment of an elastic linkage comprising electrically assisted power steering system for motor vehicles of the type steering rack;

Fig. 3 is a representation of the processing of the elastic joint shown in Fig. 2 gear and

Fig. 4 shows a longitudinal section through an electric motor to be used preferably.

The invention is based on the example of power steering explained with a rack and pinion gear. With the same we However, the invention can also apply to other assistants steering systems are used, for example those with Ku gel nut gearbox or those where the servo unit is arranged in the steering column or the rack around closes.

In Fig. 1, a housing 1 is shown as a first advantageous embodiment of the invention, in which a drive pinion 3 connected to an output member 2 is rotatably mounted. The drive pinion 3 is operatively connected via a rack 4 with steerable wheels, not shown, of a motor vehicle.

In the case of power steering systems with ball nut gears, a threaded spindle replaces the drive pinion 3 .

The output member 2 is connected via a torsionally elastic member 5 to an input shaft 6 of the power steering system.

On the drive side, the rack 4 is operatively connected via a reduction gear, preferably designed as a worm gear 7 , to a servomotor designed as an electric motor. The servo motor can also be designed as a hydraulic motor.

The housing 1 is connected to a cover 9 and a detection unit 8 , which contains a magnetoresistive sensor 10 , hereinafter referred to as (MR) sensor.

By a torque applied to the steering handwheel, who rotates the output member 2 and the input shaft 6 relative to each other.

This relative movement is implemented by means of a backlash-free gear in a proportional longitudinal movement 11 and transmitted to an annular element 12 . This annular element 12 has at least one, at least one north and south pole having magnet 17 . A transition region 13 between the individual poles lies exactly in a plane that runs perpendicular to a longitudinal axis of the annular element 12 . Via a thread 15 , the annular element 12 screws along a given axis 14 and thus performs a defined movement 11 in the longitudinal direction. In this case, the annular element 12 slides in a longitudinal movement 11 without play by using a guide 16 . The longitudinal movement 11 is measured by an (MR) sensor 10 and is further processed in a detection unit 8 .

A spring 18 ensures that the gear ar works without play.

In the embodiment according to FIG. 2, an elastic joint transmission 21 is shown, in which the input shaft 6 and the output member 2 are connected to one another in a rotationally fixed and axially fixed manner by connecting points 19 and 20 . The annular element 12 carries the magnet 17 and is via elastic intermediate members 21 with the connection points 19 and 20 coupled.

Fig. 3 shows an illustration of the development of the elastic joint transmission shown in Fig. 2. The ring-shaped element 12 and the connecting points 19 and 20 are interconnected via elastic intermediate members 21 . If a steering torque is applied to the steering handwheel, this is transmitted from the input shaft 6 to the output member 2 via kinematics 23 .

The angle of rotation that occurs between the input shaft 6 and the output member 2 relative to one another is a measure of the applied steering torque and is measured by the (MR) sensor 10 and passed on to the detection unit 8 .

The output member 2 is connected via a worm gear 7 to an electric motor shown in FIG. 4. The main components of the electric motor 24 are a rotor 25 and a stator 26 . The stator 26 is fixed to the housing, the ro tor 25 is connected to an output shaft 27 and thus to a worm 28 . Together with a worm wheel 29, this worm 28 forms the worm gear 7 . The rotor speed is measured via a magnetic ring 30 . Via the worm 28 and the worm wheel 29 of the worm gear 7 there is a mechanical connection between the magnetic ring 30 and the drive pinion 3 connected to the output member 2 .

Reference numerals

1

casing

2nd

Output link

3rd

Drive pinion

4th

Rack

5

torsionally elastic link

6

Input shaft

7

Worm gear

8th

Registration unit

9

cover

10th

(MR) sensor

11

Longitudinal movement

12th

annular element

13

Transition area

14

axis

15

thread

16

guide

17th

magnet

18th

feather

19th

Liaison

20th

Liaison

21

elastic pontic

22

web

23

kinematics

24th

Electric motor

25th

rotor

26

stator

27

Output shaft

28

slug

29

Worm wheel

30th

Magnetic ring

Claims (6)

1. Electrically assisted power steering for motor vehicles with an input shaft ( 6 ), which is in active connection with a steering handwheel for transmitting a steering torque required for steering wheels to be steered, an output member ( 2 ), which is operatively connected to the steering wheels and with a servo motor which can directly or indirectly exert an auxiliary force on the output member ( 2 ), the input shaft ( 6 ) and the output member ( 2 ) being connected to one another via a torsionally elastic member ( 5 ) such that between the input shaft ( 6 ) and the output member ( 2 ) a limited movement is possible and a detection unit ( 8 ), which contains at least one sensor, for contactless detection of the direction and strength of a steering torque acting on the input shaft ( 6 ) and other steering-specific parameters, characterized in that the input shaft ( 6 ) with the output member ( 2 ) via ei n backlash-free gear is in operative connection, which converts the limited rotational movement between the input shaft ( 6 ) and the output member ( 2 ) into a proportional longitudinal movement ( 11 ) and this longitudinal movement ( 11 ) pointing to at least one north pole and at least one south pole , annular element ( 12 ) for the detection of all the parameters required for the function of the steering transmits, so that the relative position of the input shaft ( 6 ) and the output member ( 2 ) to one another are detected via an associated (MR) sensor ( 10 ) can be. 2. Electrically assisted power steering according to claim 1, characterized in that the transmission is designed free of play, so that the annular element ( 12 ) can only perform a longitudinal movement along an axis se ( 14 ). 3. Electrically assisted power steering for motor vehicles according to claim 2, characterized in that the annular element ( 12 ) is biased by a spring ( 18 ) to ensure the backlash of the transmission. 4. Electrically assisted power steering for motor vehicles according to claim 3, characterized in that a transition region ( 13 ) between the north and south poles lies in a plane which is perpendicular to the axis ( 14 ) of the annular element ( 12 ). 5. Electrically assisted power steering for Motor vehicles according to one of the preceding claims, characterized in that the Servomo tor is an electric motor. 6. Electrically assisted power steering for motor vehicles according to one of the preceding claims, characterized in that only one detection unit ( 8 ) for detecting the steering-specific parameters torque and steering direction is required.