Electrically assisted power steering system for motor vehicles

• US 6,422,336 B1
• Filed: 03/05/2001
• Issued: 07/23/2002
• Est. Priority Date: 06/26/1998
• Status: Expired due to Term

• Current Assignee: Robert Bosch Automotive Steering GmbH (Robert Bosch GmbH)
• Original Assignee: ZF Lenksysteme GmbH (Robert Bosch GmbH)
• Inventors: Nagel, Willi, Noder, Klaus, Abele, Wolfgang, Brenner, Peter, Budaker, Martin
• Primary Examiner(s): Hurley, Kevin
• Application Number:
  US09/720,603
• Time in Patent Office: 505 Days
• Field of Search: 180/443, 180/444, 180/445, 180/446
• US Class Current: 180/446
• CPC Class Codes: B62D 15/0215 by measuring on the steering column
• CPC Class Codes: B62D 15/0245 Means or methods for determination of the central position of the steering system, e.g. straight ahead position
• CPC Class Codes: B62D 6/10 characterised by means for sensing or determining torque
• CPC Class Codes: G01B 7/30 for measuring angles or tapers; for testing the alignment of axes
• CPC Class Codes: G01D 5/145 influenced by the relative movement between the Hall device and magnetic fields see G01R33/06
• CPC Class Codes: G01L 3/104 involving permanent magnets
• CPC Class Codes: G01L 5/221 to steering wheels, e.g. for power assisted steering

Abstract

An electrically supported power steering system for motor vehicles includes an input shaft, which is mechanically linked to a steering wheel for transmitting a steering torque required for steering of wheels to be steered. An output element is mechanically linked to the wheels to be steered. An electric motor, through which a servo force can be applied directly or indirectly to the output element, is arranged on the power steering system. The input shaft and the output element are connected to one another via a torsion bar. A detection unit for detection of a torque acting on the input shaft and of other steering-specific parameters includes a single pulse generator designed as a magnet ring and at least one magnetoresistive sensor.

Claims

1. An electrically supported power steering system for a motor vehicle, comprising:

an input shaft mechanically linked to a steering wheel of the motor vehicle, the input shaft being configured to transmit a steering torque to steer the wheels of the motor vehicle;

an output element mechanically linked to the wheels of the motor vehicle to be steered;

a torsionally flexible element connecting the input shaft and the output element, the torsionally flexible element providing a limited torsion movement between the input shaft and the output element;

a servomotor configured to apply a servo power to the output element; and

a detection unit configured to contactlessly detect a direction and an intensity of the steering torque imparted on the input shaft and at least one steering-specific parameter, the detection unit including at least one sensor connected to one of the input shaft and the output element, the at least one steering-specific parameter including at least one of a torque, a steering rate and a steering acceleration;

wherein the detection unit includes a single pulse generator, the single pulse generator including a magnet ring, at least one of a peripheral surface and an end face of the magnet ring including alternating magnetic north and magnetic south poles so that a relative position between the input shaft and the output element and a change in position of the one of the input shaft and the output shaft are detectable by the at least one sensor.

2. The electrically supported power steering system according to claim 1, wherein the servomotor is configured to apply the servo power directly to the output element.

3. The electrically supported power steering system according to claim 1, wherein the servomotor is configured to apply the servo power indirectly to the output element.

4. The electrically supported power steering system according to claim 1, further comprising a stationary sensor housing and a flat spiral spring, the at least one sensor including a rotating part, the flat spiral spring electrically connecting the rotating part and the stationary sensor housing.

5. The electrically supported power steering system according to claim 1, further comprising a stationary sensor housing and a wiper unit, the at least one sensor including a rotating part, the wiper unit electrically connecting the rotating part and the stationary sensor housing.

6. The electrically supported power steering system according to claim 1, further comprising a gear arranged on the one of the output element and the input shaft, the gear configured to convert a plurality of revolutions of the input shaft into one of a small rotational movement and a small translational movement.

7. The electrically supported power steering system according to claim 6, further comprising a threaded nut and an axial guide, the axial guide being configured to guide the threaded nut axially and non-rotatably, the gear including a thread connected to the output element and the threaded nut.

8. The electrically supported power steering system according to claim 7, further comprising a magnet connected to the threaded nut, the magnet configured to generate a signal in accordance with an axial movement and in accordance with an absolute steering angle.

9. The electrically supported power steering system according to claim 7, further comprising:

a first magnetoresistive sensor configured to detect the at least one steering-specific parameter;

a second magnetoresistive sensor configured to detect an absolute steering angle; and

a common electronic unit including a common circuit board, the first magnetoresistive sensor and the second magnetoresistive sensor being arranged on the common circuit board.

10. The electrically supported power steering system according to claim 1, wherein the servo motor includes an electric motor.

11. The electrically supported power steering system according to claim 10, wherein the at least one sensor of the detection unit is configured as a single unit, the at least one sensor being configured to detect the steering torque, a steering direction, a steering angle, an absolute steering angle, the steering rate, the steering acceleration and a rotor speed of the electric motor.