Linear distance sensor and the use thereof as actuator for motor vehicles

• US 20030000307A1
• Filed: 07/12/2002
• Published: 01/02/2003
• Est. Priority Date: 01/13/2000
• Status: Active Grant

• Current Assignee: Continental Teves AG & Co. OHG (Continental AG)
• Original Assignee: Continental Teves AG & Co. OHG (Continental AG)
• Inventors: Lohberg, Peter
• Granted Patent: US 6,823,725 B2
• Time in Patent Office: Days
• US Class Current: 73/514.16
• CPC Class Codes: F16H 59/105 consisting of electrical switches or sensors
• CPC Class Codes: F16H 59/70 dependent on the ratio established
• CPC Class Codes: G01D 5/145 influenced by the relative movement between the Hall device and magnetic fields see G01R33/06

Abstract

The present invention relates to a linear distance sensor for motor vehicles which comprises a displaceable element (4, 5, 7) and a stator (1, 2, 3). The displaceable element includes a magnetic encoder. Sensor modules that operate according to the AMR principle, GMR principle, or Hall principle are linked stationarily to the stator. The displaceable element is guided by way of a bearing (11) that is connected to the stator and embraces and axially guides the displaceable element. The sensor module(s) is/are linked stationarily to the stator. The field-generating means is/are positively connected to the displaceable element along the longitudinal axis of the displaceable element.

The present invention further relates to the use of the linear distance sensor for measuring the pedal or lever position in an actuating device for brakes of motor vehicles.

Claims

1. Linear distance sensor for motor vehicles with at least one axially displaceable element (4, 5, 7) composed of one part or several parts and a stator (1, 2, 3), wherein one or more field-generating means (9, 9′

) with a permanently existing modulated course (33) of lines of magnetic flux and/or a modulated magnetic field strength is/are arranged in the displaceable element, and the field-generating means along its/their longitudinal axis include(s) at least one permanent-magnetic material with a modulated course of lines of flux and/or a modulated field strength (31, 32), and wherein one or more sensor modules are stationarily connected to the stator and carry at least one magnetic field sensor (S, S′

) and, optionally, one or more sensor circuits (SC, SC′

), the said sensor module(s) converting the course of lines of magnetic flux completely or partially into output signals that can be further processed, and wherein the magnetic field sensors operate either according to the AMR principle, the GMR principle, or the Hall principle, characterized in that the displaceable element is guided by means of a bearing (11) connected to the stator and embracing the displaceable element at least partly and thereby guiding it axially, in that the sensor module(s) is/are stationarily connected to the stator, and in that along the longitudinal axis of the displaceable element the field-generating means is/are positively connected to the displaceable element.

2. Linear distance sensor as claimed in claim 1, characterized in that the form-locking connection is established by at least one of the following steps:

fitting an elongate field-generating means (73) into a recess (74) on the surface (72) of the displaceable element,

using a special section tube with an axial recess (76) and an inside surface (72), and fitting an elongate field-generating means (73) into another recess (75) which is provided on the inside surface (72),

inserting a field-generating means (9, 9′

) into a bore (92, 93, 92′

, 93′

) that is arranged in the area of the periphery (71) of the displaceable element and extends in parallel to the main axis of the displaceable element, or using a special section tube with an axial recess (76) and with an outside peripheral area of the special section tube (71), and manufacturing an annular fit, with the field-generating means (91) being slipped into the displaceable element, wherein it applies for all steps that the surface of the displaceable element (72) is generally devoid of projections and indentations.

3. Linear distance sensor as claimed in claim 1 or 2, characterized in that the magnetic field sensors operate according to the AMR principle.

4. Linear distance sensor as claimed in at least any one of claims 1 to 3, characterized in that the displaceable element is comprised of a shank (7) which carries the field-generating means, an actuating element (4) mechanically connected to the shank, and a force take-over means (6), so that upon actuation of the actuating element (4) by means of an outside force which acts upon the force take-over means, the shank and, thus, the field-generating means is displaced axially in a way substantially free from tensile forces and/or pressure forces.

5. Linear distance sensor as claimed in at least any one of claims 1 to 4, characterized in that a magnetic return path (281, 282) is integrated into the shank.

6. Linear distance sensor as claimed in at least any one of claims 1 to 5, characterized in that there is provision of sealing means (10, 11) which protect the field-generating means against contaminants and corrosion.

7. Linear distance sensor as claimed in claim 6, characterized in that the sealing means (10, 11) comprise pleated bellows, rubber sleeves (10), and slide seals (11).

8. Linear distance sensor as claimed in at least any one of claims 1 to 7, characterized in that the stationary connection between the sensor module(s) and the stator is effected by a sensor carrier (2) which is a component part of the stator and coupled to it in a mechanically detachable fashion.

9. Linear distance sensor as claimed in at least any one of claims 1 to 8, characterized in that a redundant function is ensured by the arrangement of at least two magnetic field sensors in the linear distance sensor, wherein the magnetic field sensors either tap the magnetic field of a joint field-generating means, or some or all sensors tap the magnetic field of a field-generating means respectively associated with a magnetic field sensor.

10. Linear distance sensor as claimed in claim 9, characterized in that a first magnetic field sensor is arranged with respect to a second magnetic field sensor offset in an axial direction by up to a magnetic field period so that the output signal of the second magnetic field sensor is phase-shifted by the output signal of the first magnetic field sensor.

11. Linear distance sensor as claimed in claim 9 or 10, characterized in that at least one magnetic field sensor is provided which has a lower resolution ability compared to another magnetic field sensor provided in the arrangement.

12. Linear distance sensor as claimed in at least any one of claims 4 to 11, characterized in that the shank (7) is a cylinder-shaped tube, the permanent-magnetic material (91) has the shape of a cylinder-shaped tube, wherein the magnetic field along the longitudinal axis of the magnetic material is radially symmetrical (28a, 28b), and the permanent-magnetic material is slipped into the axial recess (76) of the shaft.

13. Linear distance sensor as claimed in at least any one of claims 1 to 12, characterized in that at least one sensor module comprises a bridge circuit made up of magnetic field sensors (13), whose main plane (131) is arranged in parallel to the surface normal (r) and the longitudinal axis (X) of the displaceable element.

14. Linear distance sensor as claimed in at least any one of claims 1 to 10, characterized in that at least one sensor module comprises a bridge circuit made up of magnet sensors (15), whose main plane (151) is aligned vertically to the surface normal (r) of the displaceable element.

15. Use of the linear distance sensor as claimed in at least any one of claims 1 to 14 for measuring the pedal or lever position of an actuating device for brakes of motor vehicles.