Ball joint

Abstract

The invention relates to a ball joint comprising a housing (3) having a pin opening (2); a ball pin (5) which extends in an axial direction (x) and is provided with a joint ball (4) at one axial end and the joint ball (4) of which is mounted in the housing (3) so as to be rotatable about an axial ball pin axis (8) extending through the center (7) of the joint ball (4), the ball pin (5) extending out of the housing through the pin opening (2); a magnetic-field-sensitive sensor (9) which is provided on the housing (3) opposite the pin opening (2) in the direction of a housing axis (10) running through the pin opening (2) and through the center of the joint ball (7), the housing axis (10) being tiltable with respect to the ball pin axis (8); and at least one permanent magnet (12) which is provided on a pole (11) of the joint ball (4) and is magnetized transversely with respect to the ball pin axis (8) and the magnetic field (13) of which flows through the magnetic-field-sensitive sensor (9), the magnetic-field-sensitive sensor being used to detect a rotation of the permanent magnet (12), and thus of the ball pin (5) about the ball pin axis (8), and provide a rotation angle signal (Sd) characterizing said rotation, the course of at least one field line (17) of the magnetic field (13) being adapted to the course of at least one trajectory (15) of the magnetic-field-sensitive sensor (9) or of a sensor point (16) representing said trajectory.

Description

[0001] ball joint

[0002] The invention relates to a ball joint with a housing having a pin opening, a ball stud extending in an axial direction and provided with a ball joint at one axial end, the ball stud being rotatably mounted in the housing about an axial ball stud axis extending through the center of the ball joint, the ball stud extending out of the housing through the pin opening, a magnetic field-sensitive sensor provided on the housing opposite the pin opening in the direction of a housing axis extending through the pin opening and through the center of the ball joint, the housing being tiltable with its housing axis relative to the ball stud axis, and at least one permanent magnet provided at one pole of the ball joint and magnetized transversely to the ball stud axis, the magnetic field of which permeates the magnetic field-sensitive sensor.by means of which a rotation of the permanent magnet and thus of the ball stud about the ball stud axis can be detected and a rotation angle signal characterizing this rotation can be provided.

[0003] If there is no tilt of the housing axis relative to the ball stud axis, the rotation can be measured with low error. However, as the tilt increases, the error rises, making the rotation angle signal less reliable.

[0004] Based on this, the invention is particularly aimed at reducing the error in rotation measurement when the housing axis is tilted relative to the ball stud axis.

[0005] This problem is solved according to the invention with a ball joint according to claim 1. Preferred embodiments of the invention are given in the dependent claims and in the following description.

[0006] A ball joint with a housing having a pin opening, a ball stud extending in an axial direction and provided with a ball joint at one axial end, the ball stud being rotatably mounted in the housing about an axial ball stud axis passing through the center of the ball joint, the ball stud extending out of the housing through the pin opening, a magnetic field-sensitive sensor provided on the housing opposite the pin opening in the direction of a housing axis passing through the pin opening and the center of the ball joint, the housing being tiltable with its housing axis relative to the ball stud axis, and at least one permanent magnet provided at one pole of the ball joint and magnetized transversely to the ball stud axis, the magnetic field of which permeates the magnetic field-sensitive sensor.The device by means of which a rotation of the permanent magnet and thus of the ball stud about the ball stud axis can be detected and a rotation angle signal characterizing this rotation can be provided, is further developed according to the invention in particular by the fact that the course of at least one field line of the magnetic field is adapted to the course of at least one trajectory of the magnetic field-sensitive sensor or a sensor point representing it.

[0007] The feature that the course of at least one field line of the magnetic field is adapted to the course of at least one trajectory of the magnetic field-sensitive sensor or a sensor point representing it allows the error in rotation measurement to be reduced in the presence of tilting.

[0008] It is known that the shape of a permanent magnet can influence the magnetic field pattern of that magnet. This effect is also known, for example, as magnetic shape anisotropy. Thus, by selecting a suitable shape for the permanent magnet, it is possible to generate a magnetic field in which a curve corresponding to at least one trajectory in terms of shape and length lies, in particular at least approximately, on at least one field line of the permanent magnet. This permanent magnet is then to be positioned at a suitable location on the ball joint such that the trajectory lies, in particular at least approximately, on the at least one field line.In particular, the permanent magnet is shaped and arranged in such a way and / or the shape of the permanent magnet and its distance to the center of the ball joint are chosen such that the course of at least one field line of the magnetic field is adapted to the course of at least one trajectory of the magnetic field-sensitive sensor or a sensor point representing it.

[0009] Since the magnetic field-sensitive sensor has a spatial extent in reality, it is preferably represented by the sensor point or a sensor point. This is, for example, a point of highest sensitivity and / or a point of highest measurement accuracy and / or a geometric center of gravity of the magnetic field-sensitive sensor and / or a geometric center point with respect to an arrangement of several sensor elements of the magnetic field-sensitive sensor, or the like.

[0010] A direction perpendicular to the ball journal axis or the housing axis is specifically referred to as a radial direction. The expression "at least one" also includes the meaning of "one" or "exactly one".

[0011] According to an advantageous embodiment, at least one trajectory of the magnetic field-sensitive sensor or sensor point lies, in particular at least approximately, on at least one field line of the magnetic field. This is, for example, one way of ensuring that the course of the at least one field line of the magnetic field is adapted to the course of the at least one trajectory of the magnetic field-sensitive sensor or sensor point.

[0012] The magnetic field-sensitive sensor or sensor point can typically tilt in two spatial directions around the center of the ball joint, such that the trajectories of the magnetic field-sensitive sensor or sensor point lie on a spherical surface. Preferably, the permanent magnet is shaped such that at least one field line of the magnetic field runs, advantageously at least partially, and in particular at least approximately, on a spherical surface. According to an advantageous embodiment, the course of several field lines of the magnetic field is adapted to the course of several trajectories of the magnetic field-sensitive sensor or the sensor point representing it.In particular, the permanent magnet is shaped and arranged in such a way and / or the shape of the permanent magnet and its distance to the center of the ball joint are chosen such that the course of several field lines of the magnetic field is adapted to the course of several trajectories of the magnetic field-sensitive sensor or the sensor point representing it.

[0013] Preferably, several or the multiple trajectories of the magnetic field-sensitive sensor or sensor point lie, in particular at least approximately, on a field line or on one of the field lines of the magnetic field. Preferably, the permanent magnet is shaped such that several or the multiple field lines of the magnetic field run, advantageously at least sectionally, in particular at least approximately, on a spherical surface.

[0014] The permanent magnet is preferably diametrically magnetized. According to an advantageous embodiment, the permanent magnet is a round magnet, preferably diametrically magnetized, or is based on one. The permanent magnet or round magnet is particularly cylindrical and has a height and a diameter. A diametrically magnetized round magnet has proven effective in practice for measuring angles of rotation.

[0015] Preferably, the height and diameter of the permanent magnet, which is in particular cylindrical or round, and its distance to the center of the ball joint are selected such that the course of at least one or more or the at least one or the several field lines of the magnetic field is adapted to the course of at least one or more or the at least one or the several trajectories of the magnetic field-sensitive sensor or the sensor point representing it.

[0016] Preferably, the height and diameter of the permanent magnet, which is in particular cylindrical or round, are selected such that at least one or more or the at least one or the several trajectories of the magnetic field-sensitive sensor or sensor point, in particular at least approximately, preferably each, lie on one or on at least one or on the at least one field line or on one of the field lines of the magnetic field.

[0017] Advantageously, the height and diameter of the permanent magnet, which is in particular cylindrical or round, are selected such that at least one or more field lines of the magnetic field run, advantageously at least sectionally, and in particular at least approximately, on a spherical surface.

[0018] According to an advantageous embodiment, the geometric dimensions of the permanent magnet decrease transversely to the ball-pin axis with increasing distance from the center of the ball joint, for example continuously or in steps. Advantageously, the geometric dimensions of the steps also decrease in the direction of the ball-pin axis with increasing distance from the center of the ball joint.

[0019] Preferably, the shape of the permanent magnet, which is in particular cylindrical or round, has several, preferably two, cylinders arranged one above the other, the diameter and height of which decrease with increasing distance from the center of the ball joint.

[0020] The ball stud is preferably rotationally symmetrical or substantially rotationally symmetrical with respect to the ball stud axis. For example, the ball stud is formed in one piece. Alternatively, the ball stud has, for example, a pin that is attached to the ball joint. Preferably, the ball stud is made of metal. For example, the ball stud is made of an iron-based material such as steel.

[0021] Preferably, the ball stud with its ball joint is mounted in the housing by means of a bearing shell, which is particularly rotatable and / or tiltable. The bearing shell is made, for example, of plastic or metal. For example, the bearing shell is made of a ferrous material such as steel.

[0022] Preferably, the permanent magnet is connected to the ball joint via a spacer made of a non-magnetic material. The spacer prevents, in particular, a short circuit of the magnetic field lines via the ball stud if the latter is made of a magnetic material, preferably a ferromagnetic material.

[0023] The ball joint is intended for use in a vehicle. Preferably, the ball joint is located in the wheel suspension of the vehicle. The vehicle is, in particular, a motor vehicle, such as an agricultural vehicle.

[0024] The invention is described below with reference to preferred embodiments and the drawing. The drawing shows:

[0025] Fig. 1 shows an exploded view of a ball joint according to a first embodiment,

[0026] Fig. 2 shows a side view of a magnetic field-sensitive sensor and a ball stud with a permanent magnet sitting in a bearing shell according to the first embodiment.

[0027] Fig. 3 shows a partial longitudinal section through the ball joint according to the first embodiment,

[0028] Fig. 4 shows a schematic representation of a trajectory of the magnetic field-sensitive sensor and the permanent magnet according to the first embodiment,

[0029] Fig. 5 shows a schematic side view of the trajectory of the magnetic field-sensitive sensor and the permanent magnet with field lines according to the first embodiment; Fig. 6 shows a schematic representation of a trajectory of a magnetic field-sensitive sensor and a permanent magnet according to a second embodiment.

[0030] Fig. 7 shows a schematic side view of the trajectory of the magnetic field-sensitive sensor and the permanent magnet according to the second embodiment and

[0031] Fig. 8 shows three schematic representations of permanent magnets according to further embodiments.

[0032] Figures 1 to 5 show different views and partial views of a ball joint 1 according to a first embodiment, which comprises a housing 3 having a pin opening 2, a ball stud 5 extending in an axial direction x and provided at one axial end with a ball joint 4, the ball stud 5 being rotatably mounted in the housing 3 with its ball joint 4 via a bearing shell 6 about an axial ball stud axis 8 passing through the center point 7 of the ball stud 4, the ball stud 5 extending out of the housing 3 through the pin opening 2, and a magnetic field-sensitive sensor 9 provided on the housing 3 opposite the pin opening 2 in the direction of a housing axis 10 passing through the pin opening 2 and through the center point 7 of the ball stud 4, the housing axis 10 being tiltable relative to the ball stud axis 8.and has at least one permanent magnet 12 provided at one pole 11 of the ball joint 4 and magnetized transversely to the ball pin axis 8, the magnetic field 13 of which permeates the magnetic field-sensitive sensor 9, by means of which a rotation of the permanent magnet 12 and thus of the ball pin 5 about the ball pin axis 8 can be detected and a rotation angle signal Sd characterizing this rotation can be provided. The permanent magnet is attached to the ball joint 4 by means of a spacer 14, which is made of a non-magnetic material. The housing 3 has a mounting opening 20 opposite the pin opening 2 in the direction of its housing axis 10, which is closed by a cover plate 21, which is fastened to the housing 3 by screws 22 or other fasteners. On the cover plate 21, which is made of a non-magnetic material,The magnetic field-sensitive sensor 9 is attached externally by means of a sensor holder 23, which is fastened to the cover plate 9 with screws 24 or other fastening means. The cover plate 21 is specifically considered part of the housing 3.

[0033] The permanent magnet 12 is a diametrically magnetized round magnet and is therefore cylindrical. It has a diameter D and a height H and is arranged at a distance A from the center of the ball joint, as can be seen in Fig. 3. The distance between the permanent magnet 12 and the magnetic field-sensitive sensor 9 is denoted by d. The poles of the magnet are labeled N for the north pole and S for the south pole.

[0034] Figures 4 and 5 show a trajectory 15 of the magnetic field-sensitive sensor 9, which is represented here only by a sensor point 16. Figure 5 shows that the trajectory 15 lies on a field line 17 of the magnetic field 13.

[0035] Figures 6 and 7 show schematic representations of a trajectory 15 of a magnetic field-sensitive sensor and a permanent magnet 12 according to a second embodiment, wherein features identical or similar to those of the first embodiment are designated with the same reference numerals as in the first embodiment. The magnetic field-sensitive sensor is shown here only in the form of a sensor point 16 representing it.

[0036] In contrast to the first embodiment, the shape of the permanent magnet 12, which is designed as a round magnet, has two cylinders 18 and 19 arranged one above the other, the diameter and height of which decrease with increasing distance from the center point 7 of the ball joint 4. Apart from these differences, the second embodiment is identical to the first embodiment, so for a further description of the second embodiment, reference is made to the description of the first embodiment. For example, the permanent magnet according to the second embodiment can replace the permanent magnet according to the first embodiment.

[0037] Fig. 8 shows three schematic representations of permanent magnets 12 according to other embodiments.

[0038] In contrast to the first embodiment, the permanent magnets 12 in the other embodiments have a different shape. Apart from these differences, the other embodiments are essentially identical to the first embodiment, so reference is made to the description of the first embodiment for a further description of the other embodiments.

[0039] 1 ball joint

[0040] 2 pin openings

[0041] 3 cases

[0042] 4 ball joints

[0043] 5 ball studs

[0044] 6 bearing cup

[0045] 7 Center of the joint ball

[0046] 8 ball stud axle

[0047] 9 magnetic field-sensitive sensor

[0048] 10 Housing axis

[0049] 11 pole of the ball joint

[0050] 12 permanent magnets

[0051] 13 Magnetic field

[0052] 14 spacers

[0053] 15 Trajectory

[0054] 16 Sensor point representing the sensor

[0055] 17 Field line of the magnetic field

[0056] 18 cylinders of the permanent magnet

[0057] 19 cylinders of the permanent magnet

[0058] 20 Mounting opening

[0059] 21 Housing cover plate

[0060] 22 screw

[0061] 23 sensor holders

[0062] 24 screws

[0063] A Distance of the permanent magnet from the center of the sphere D Diameter of the permanent magnet

[0064] d distance of the permanent magnet from the sensor

[0065] H Height of the permanent magnet

[0066] Sd rotation angle signal

[0067] x axial direction

Claims

Patent claims 1. Ball joint with a housing (3) having a pin opening (2), a ball stud (5) extending in an axial direction (x) and provided at one axial end with a ball joint (4), the ball stud being rotatably mounted in the housing (3) with its ball joint (4) about an axial ball stud axis (8) extending through the center point (7) of the ball joint (4), the ball stud (5) extending out of the housing through the pin opening (2), a magnetic field-sensitive sensor (9) being provided on the housing (3) opposite the pin opening (2) in the direction of a housing axis (10) extending through the pin opening (2) and through the center point of the ball joint (7), the housing being tiltable with its housing axis (10) relative to the ball stud axis (8), and at least one permanent magnet (12) provided at one pole (11) of the ball joint (4) and magnetized transversely to the ball stud axis (8),the magnetic field (13) of which the magnetic field-sensitive sensor (9) is permeated, by means of which a rotation of the permanent magnet (12) and thus of the ball stud (5) about the ball stud axis (8) can be detected and a rotation angle signal (Sd) characterizing this rotation can be provided, characterized in that the course of at least one field line (17) of the magnetic field (13) is adapted to the course of at least one trajectory (15) of the magnetic field-sensitive sensor (9) or of a sensor point (16) representing it.

2. Ball joint according to claim 1, characterized in that the at least one trajectory (15) of the magnetic field-sensitive sensor (9) lies on the at least one field line (17) of the magnetic field (13).

3. Ball joint according to claim 1 or 2, characterized in that the permanent magnet is shaped such that the at least one field line (17) of the magnetic field (13) runs at least sectionally on a spherical surface.

4. Ball joint according to one of the preceding claims, characterized in that the course of several field lines (17) of the magnetic field is adapted to the course of several trajectories (15) of the magnetic field-sensitive sensor (9) or sensor point (16).

5. Ball joint according to one of the preceding claims, characterized in that several trajectories (17) of the magnetic field-sensitive sensor (9) each lie on a field line (17) of the magnetic field (13).

6. Ball joint according to one of the preceding claims, characterized in that the permanent magnet (12) is shaped such that several field lines (17) of the magnetic field (13) run at least sectionally on a spherical surface.

7. Ball joint according to one of the preceding claims, characterized in that the permanent magnet (12) is a diametrically magnetized round magnet or is based on one.

8. Ball joint according to one of the preceding claims, characterized in that the geometric dimensions of the permanent magnet (12) decrease transversely to the ball pin axis (8) with increasing distance to the center (7) of the joint ball.

9. Ball joint according to one of the preceding claims, characterized in that the geometric dimensions of the permanent magnet (12) decrease stepwise transversely to the ball pin axis (8) with increasing distance to the center (7) of the joint ball (4) and furthermore the geometric dimensions of the steps decrease in the direction of the ball pin axis (8) with increasing distance to the center (7) of the joint ball (4).

10. Ball joint according to one of the preceding claims, characterized in that the shape of the permanent magnet (12) has several cylinders (18, 19) arranged one above the other, the diameter and height of which decrease with increasing distance to the center (7) of the joint ball (4).

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