CN102686980B - Magnetic field sensor device for detecting displacement of moving elements - Google Patents

Abstract

The invention relates to a magnetic field sensor device for detecting displacements on a moving element, wherein the magnetic field of a magnetic system on the moving element changes direction within a displacement range (6) to be detected, whereby the position thereof relative to a stationary sensor (5) can be detected accordingly. At least one magnet (3, 4; 7; 11, 12; 14) is provided as a component of the magnetic system or a further magnetic element on the element which moves in a linear or other degree of freedom, the outer circumference of which is arranged at a predetermined distance opposite at least one stationary sensor (5) which is sensitive to the direction of the magnetic field, wherein the preferred direction of the magnetic field of the magnet (3, 4; 7; 11, 12; 14) is oriented at a predetermined angle between 0 DEG and 90 DEG relative to the displacement (6) of the moving element.

Description

Magnetic field sensor device for detecting displacement of moving elements

technical field

The invention relates to a magnetic field sensor device for detecting displacements of rotary and/or linear motion elements, in which magnetic field sensor device, according to the features stated in the preamble of claim 1, the spatial components of the magnetic field are located in the area to be detected. Changes within the displacement range can be detected accordingly.

Background technique

It is known, for example, in speed sensors and position sensors, such as those used to control the engine or also in the transmission control or driving dynamics control of motor vehicles, that a rotational movement or a change in position is caused by a change in the magnetic field corresponding to the rotational movement or position change to test. Magnetic sensors known per se are generally used here, which, depending on the application and field of use, can be Hall sensors, AMR sensors, GMR sensors, TMR sensors or generally XMR sensors.

For example, it is known from EP00997706B1 that in order to detect a linear position between a magnet and a sensor sensitive to a magnetic field in terms of magnetization direction, the magnet is constructed in the direction of the displacement to be detected so that the magnet has a distribution over its length and Magnetic field lines at varying angles to the direction of motion. The position of the sensor relative to the magnet can thus be determined from the current magnetic field direction.

It is also known from DE 199 37 206 C2 that a scale moving relative to a magnetic field-sensitive sensor has a plurality of individual magnets, and that the north and south poles of these magnets point in different directions along the scale.

To date, these sensor arrangements have generally been used for the detection of relatively long measuring displacements, wherein either the sensor is longer than the measuring displacement with measuring elements arranged one behind the other along the measuring displacement, or the measuring displacement is relatively longer than the sensor. In both cases, problems often arise when fitting into a narrow space, as is often the case when installing in a motor vehicle, for example, when installing a pedal travel sensor for the brake pedal or accelerator pedal .

Contents of the invention

It is therefore the object of the present invention to achieve a spatially optimal installation of sensor units for detecting displacements in different operating mechanisms. Therefore, the present invention is based on a magnetic field sensor device for detecting displacements of a moving element, in which the spatial components of the magnetic field of a magnetic element or of a magnetic system on the moving element change direction within the displacement range to be detected on the magnetic element, whereby The relative position to the sensor can be detected accordingly. According to the invention, at least one magnet or magnetic element is arranged on the substantially linear or also rotationally movable element, the outer periphery of which is arranged opposite at a predetermined distance at least one magnetic field-sensitive sensor which is stationary, wherein the magnetic element The magnetic field of the magnetic field is oriented at a predetermined angle between the axial direction and the radial direction with respect to the direction of motion of the moving part. Here, the angular range of detectable magnetic field directions can reach a maximum of 200° during displacement detection.

For example, when using the magnetic field sensor device according to the invention for pedal stroke detection of a motor vehicle, the magnetizing element can be mounted on an actuating element, for example in a vehicle braking system, which operates in a direction other than the linear direction to be detected. On the other axis, in most cases it is rotational movement or movement with another degree of freedom. The invention is therefore also suitable for narrow installation situations in motor vehicles, but on the other hand can also be used in various applications outside the vehicle braking system.

Advantageously, for measuring the spatial components of the magnetic field, sensors using the XMR effect or Hall sensors are used as magnetic field sensors, which detect the direction of change of the magnetic field during linear movement or during movement in other degrees of freedom, respectively.

In a preferred embodiment of the magnetic field sensor arrangement according to the invention, the angle to the direction of linear movement of the rotary motion element is advantageously in the range of 45°. Thus, the magnetic circuit has at least one magnetization direction which is different from, but not perpendicular to, the axis of the direction of movement. By means of this so-called magnetic field inclination, a magnetic field is generated at the sensor which has a relatively wide measuring range with respect to detectable directional differences of the lines of force. However, when using at least two magnets, there is still a deviation between the magnetic field directions of these magnets.

If the moving element has a ring magnet, the magnetic circuit is embodied rotationally symmetrical and thus rotatable about the axis of the direction of movement without causing a change in the direction of the magnetic field at the sensor being detected.

The magnetic circuit for the magnetic field sensor according to the invention therefore preferably also consists of at least one magnet rotatable about an axis in the direction of linear motion, which generates a magnetic field which is continuously and monotonically stable over the linear displacement range to be measured change the direction of the magnetic field. Therefore, especially in the case of long measuring displacements, the magnetic system can be shorter than the measuring displacement.

A relatively short magnetic field sensor and at the same time a relatively short magnetic system can be realized by means of the invention, but a relatively long measuring displacement can also be realized for applications with narrow installation spaces (both magnetic field sensor and magnetic system are shorter than the measuring displacement ). Nevertheless, the magnetic circuit described here generates as detectable a change in the direction of the magnetic field as possible over the measured displacement.

The invention can be realized by means of a magnetic system which is flexible with regard to the number of magnets, the direction of magnetization (individually or in combination), and can be used in different installation spaces, in different applications and with different measuring displacements.

Description of drawings

The implementation examples of the present invention will be described in detail below with the aid of the accompanying drawings. In the attached picture:

Figure 1 shows a schematic diagram of the so-called skew magnetization consisting of two individual magnets and a sensor that detects the direction of the magnetic field;

Figure 2 shows a schematic diagram of the so-called skew magnetization by a single magnet and a sensor that detects the direction of the magnetic field;

FIG. 3 shows an embodiment of a device for measuring pedal travel in a motor vehicle with a magnetic field sensor device according to the invention;

FIG. 4 shows a detailed view of a ring magnet of the magnetic field sensor device shown in FIG. 3 .

detailed description

The magnetic circuit shown schematically in FIG. 1 for explaining the invention consists of two individual magnets 1 and 2 , whose magnetic field lines 3 and 4 here are shown schematically running obliquely in a preferred direction. The lines of force 3 or 4 intersect with a sensor 5 sensitive to a magnetic field (here in the case shown the line of force 3 intersects the sensor 5), wherein it can be seen that the direction of the lines of force 3 or 4 is in line with the straight line of the sensor 5 in the magnetic circuit It depends on exactly which relative position in the displacement section 6 it is in. If a sensor 5 is used, for example, an XMR sensor (thin film magnetoresistive sensor) or a Hall sensor, and the output signal of said sensor is just related to the direction of the intersecting magnetic field lines 3 or 4, then the principle structure can be used to determine the , The relative position between the magnetic circuit composed of 2 and the sensor 5.

FIG. 2 shows a further solution for this position determination by means of a single magnet 7 magnetized obliquely in a preferred direction, so that the field lines 8 of this magnet can here depend on the direction of the intersecting field lines 8 in the same way as in FIG. 1 The relative position between magnet 7 and sensor 5 is determined.

FIG. 3 shows an embodiment of a magnetic field sensor device according to the invention, for example a magnetic field sensor device for pedal stroke measurement in a vehicle braking system, wherein a magnetic field sensitive sensor (corresponding to sensor 5 in the preceding figures) is It is housed in the sensor housing 10 . The magnetic circuit has two ring magnets 11 and 12 , which are rotatable on a rotation axis 13 and can move linearly along the rotation axis 13 .

FIG. 4 shows as a detailed exemplary embodiment a ring magnet 11 (or respectively 12 ), which here is magnetized obliquely in a preferred direction 14 , for example at 45° relative to the axis of rotation 13 according to FIG. 3 .

Claims (7)

1. A magnetic field sensor device for detecting a displacement on a moving element, wherein the spatial components of the magnetic field of the magnetic system on the moving element change direction within the range of the displacement (6) to be detected, whereby it is possible to detect accordingly Its position relative to the fixed sensor (5) is characterized in that at least one magnet (3, 4; 7; 11, 12; 14) is provided as A component part of the magnetic system or provided with a further magnetic element, the outer periphery of the at least one magnet or other magnetic element is arranged opposite at a predetermined distance at least one sensor (5) fixed in position and sensitive to the direction of the magnetic field, wherein , the predetermined angular displacement (6) of the magnetic field of the magnets (3, 4; 7; 11, 12; 14) relative to said moving element is between 0° and 90°. 2. The magnetic field sensor arrangement according to claim 1, characterized in that the further degree of freedom comprises a rotational movement about a rotational axis (13) of the moving element. 3. Magnetic field sensor device according to claim 1 or 2, characterized in that the predetermined angle of the magnetic field of the magnets (3, 4; 7; 11, 12; 14) is 45°. 4. The magnetic field sensor arrangement according to claim 1, characterized in that, for measuring the spatial components of the magnetic field, at least one magnetic field sensor is a sensor (5) using the XMR effect or a Hall sensor. 5. The magnetic field sensor arrangement as claimed in claim 1, characterized in that a plurality of individual magnets, which are also oriented differently with regard to their magnetization, are arranged on the circumference of the moving element. 6. The magnetic field sensor device according to claim 1, characterized in that at least one ring magnet (11, 12) is arranged on the moving element, this magnet has a magnetic field direction on its circumferential direction, the predetermined angle of the magnetic field direction The displacement (6) relative to said moving element is between 0° and 90°. 7. Use of the magnetic field sensor device according to claim 1, characterized in that the magnetic field sensor device is used for pedal travel measurement in a motor vehicle.