EP1861629A1

EP1861629A1 - Joint for a motor vehicle

Info

Publication number: EP1861629A1
Application number: EP05728298A
Authority: EP
Inventors: Metin Ersoy; Martin Rechtien; Joachim Spratte; Frank Budde; Armin Müller
Original assignee: ZF Friedrichshafen AG
Current assignee: ZF Friedrichshafen AG
Priority date: 2005-03-22
Filing date: 2005-03-22
Publication date: 2007-12-05
Also published as: DE112005003591A5; CN101147006A; CN100572841C; US20090232590A1; WO2006099821A1; JP2008534863A

Abstract

The invention relates to a joint for a motor vehicle, comprising a housing (5), a bearing shell (4), arranged within the housing (5), a bearing pin (3), comprising a bearing region (1) and a pin region (2), mounted with the bearing region (1) in the bearing shell (4) to pivot and/or rotate and at least one tensioning means (33) arranged in the housing (5) embodied as a solid body and the mechanical tension thereof, exerted by the bearing shell (4) on the bearing region (1), may be adjusted, whereby the bearing shell (4) has an at least partly spring elastic embodiment and may be deformed in a spring elastic manner by the tensioning means (33).

Description

Joint for a motor vehicle

description

The invention relates to a joint for a motor vehicle, comprising a housing, a bearing shell arranged in the housing, a journal having a bearing area and a journal area, which is pivotally and / or rotatably supported by the bearing area in the bearing shell and at least one disposed in the housing and clamping means designed as a solid body, from which a mechanical stress exerted by the bearing shell on the bearing area can be changed.

Joints, in particular ball joints, require a certain torque in order to move the bearing area or the joint ball. For example, a typical torque is about 2 Nm and is intentionally created by interference fit (oversize) of the ball in the ball socket, otherwise there is an unallowable free play even after slight wear or with small tolerance deviations. However, requests have recently been made to lower torque below 1 Nm to improve ride comfort. On the other hand, it is desirable that the torque increases with increasing wheel frequency in order to dampen the wheel vibrations before they are passed on to the steering or to the chassis. So far, this request has been fulfilled by using synthetic greases and PU bearing shells, as this is the reason for the

Torque increases passively with increasing frequency. However, the effect is only marginal (maximum 3-fold increase in torque achievable) and is not always reproducible.

From DE 102 45 983 Al is a ball joint with a housing, two arranged in the housing bearing shell elements, a pin and a ball joint having joint body, with its ball joint between the two Bearing elements sitting and a housing bottom known, which is arranged on the side facing away from the pin of the housing. Between an first of the two bearing shell elements and the housing bottom, an adjustable clamping device is arranged, by means of which the bias voltage with which the joint body is clamped between the bearing shell elements, is variable. To vary the mechanical bias, the tensioner may include piezoelectric or hydraulic elements, such as a hydraulic piston.

In such a ball joint, the bias can not be very finely adjusted, as already movements in the hundredths of a millimeter range very large

Torque changes entail. Furthermore, a possibly existing radial clearance is not compensated. Also, a sliding bearing for at least one bearing shell element is required so that it can move to the other bearing shell element or move away from this, which places high demands on the manufacturing accuracy.

From DE 37 40 442 Al a ball joint with a housing, an arranged in the housing elastic bearing shell, a pin and a ball joint having pivot pin which sits with its ball joint in the bearing shell and a lid known, which faces away from the bearing pin opening the housing closes. In the bearing shell one or more chambers are formed, which are filled with a flowable medium and connected to a pressure medium source downstream valve device, so that an axial and radial adjustability of the joint ball can be achieved. Furthermore, the tilt and torque are adjustable.

Such a bearing shell must be made hollow and thus relatively thin-walled, with the risk that the wear occurring regularly in bearing shells leads to a crack or hole in the bearing shell wall. In case of damage to the pressure medium circuit, the flowable medium may leak, resulting in a large game of the journal in the housing to the uselessness of the ball joint can result. The object of the invention is to develop a joint of the type mentioned in such a way that the torque can be finer adjusted.

This object is achieved by a joint according to claim 1. Preferred developments are given in the dependent claims.

The joint for a motor vehicle according to the invention comprises a housing, a bearing shell arranged in the housing, a journal provided with a bearing area and a journal area, which is pivotally and / or rotatably mounted with the bearing area in the bearing shell and at least one disposed in the housing and as Solid-trained clamping means or clamping element or actuator, of which a force exerted by the bearing shell on the bearing area mechanical stress is variable, wherein the bearing shell is at least partially resilient and resiliently deformable by the clamping means.

With the joint according to the invention, it is possible to deform the existing in particular made of plastic bearing shell on the clamping means, resulting in a change of the force exerted by the bearing shell on the joint area voltage. As a result, a finer adjustability of the torque is achieved because a work performed by the clamping means on the bearing shell is partially converted into a deformation of the same and thus is only attenuated or damped for influencing the torque available. As material for the bearing shell, for example, polyoxymethylene (POM), polyetheretherketone (PEEK), polyurethane (PUR), polyamide (PA) or a combination of these materials can be used.

Furthermore, can be dispensed with a sliding bearing for a separate bearing shell part of a multi-part bearing shell, which simplifies the construction of the inventive joint. Also, one-piece bearings can be used, whereby the cost of manufacturing and assembly of the joint is reduced. Since the clamping means is designed as a solid body, the bearing shell made of solid material exist, so that the disadvantages associated with a filled with hydraulic fluid bearing shell disadvantages are avoidable. In particular, can be dispensed with an embedding of the trained as a solid clamping means in the bearing shell on a hollow training. Damage to the bearing shell thus does not lead to leakage of a liquid pressure medium. Even with a hole or crack in the

Bearing shell is still a functional operation of the joint, at least temporarily possible.

The joint according to the invention is arranged, for example, in a wheel suspension of a motor vehicle and may be designed as a ball joint, so that preferably a joint ball is formed by the bearing region. If a one-piece bearing shell is used, it is provided, for example, with a spherical bearing surface bearing against the joint ball, on which at least one great circle lies, which extends completely within the bearing shell and in particular forms no edge of the same. In this case, this great circle can also be a great circle on the joint ball and have the diameter. Furthermore, the joint according to the invention can be equipped with an angle sensor, which is preferably integrated in the joint and of which a rotation and / or pivoting of the bearing pin relative to the housing can be detected.

The clamping means may be formed integrally with the bearing shell, in particular integrated into the bearing shell. For such a solution, piezoelectric fibers are suitable as clamping means, which are embedded in the material of the bearing shell. The bearing shell can be made of a composite material, such as for example a plastic with embedded therein and the clamping means forming piezoceramic fibers or carbon nanotubes. By applying an electrical voltage to the bearing shell a change in length of the piezoelectric fibers can be achieved, so that the bearing shell deformed and the voltage exerted by the bearing shell on the bearing area voltage can be changed. Alternatively, however, the clamping means is separated from the bearing shell and in particular arranged outside thereof. In this case, the clamping means preferably engages on a first outer surface area of the same and is arranged, for example, between the bearing shell and the housing. In addition or as an alternative to the use of a piezoelectric material and / or the use of carbon nanotubes, it is also possible to use electrostrictive and / or magnetostrictive materials for the clamping device or the actuator.

If the first outer surface region lies on a plane which runs perpendicular to the longitudinal axis of the joint, then this is sensitive to external and axial forces acting on the joint region, since the clamping forces exerted by the bearing shell on the joint region also act against this external force. If this external force reaches or exceeds a certain size, then even the clamping effect can be canceled by a bearing shell part, in particular if the bearing shell is designed in two parts. For this reason, the first outer surface region preferably extends obliquely to the longitudinal axis of the joint and encloses with this an angle of greater than 0 ° and less than 90 °. The outer surface region is in particular designed in the shape of a truncated cone, wherein its axis of symmetry preferably coincides with the longitudinal axis of the joint. Furthermore, the tensioning means may have an oblique, for example frusto-conical, surface area and, via this, abut against the first outer surface area.

It has proven to be advantageous if the bearing shell is provided with a second oblique, for example frusto-conical outer surface region, wherein the housing has an inner wall with an oblique, for example frusto-conical inner wall region, against which abuts the second outer surface region. Oblique in this context means that the respective surface, such as the second outer surface area, with the longitudinal axis of the joint forms an angle of greater than 0 ° and less than 90 °. Furthermore, the axes of symmetry of the second outer surface region and the oblique or truncated cone-shaped inner wall region preferably coincide with the longitudinal axis of the joint. The two oblique or truncated cone-shaped outer surface regions taper in particular with increasing distance from each other. The storage area is preferably at least partially between the two outer surface areas. Especially Each of the two frustoconical outer surface areas encloses in each case a circular area at the location of its smallest diameter, the storage area being arranged at least partially between these two circular areas. In the case of a one-part design of the bearing shell, it can have a cylindrical outer surface region between the two frustoconical outer surface regions in which the bearing region is arranged.

The clamping means may be displaceable, extendible and / or shortened, so that the deformation of the bearing shell is caused by the change in the position or the outer dimensions of the clamping means, which leads to a change of the force exerted by the bearing shell on the bearing area mechanical stress. For example, the clamping means consists of a piezoelectric material, to which an electrical voltage can be applied, which leads to a change in length of the clamping means and thus to a deformation of the bearing shell. However, such a piezoelectric clamping device must be readjusted depending on the state of wear of the bearing shell, which is disadvantageous in continuous operation of the joint. For this reason, the clamping means is preferably a displaceably mounted in the housing body, in particular piston, which can be moved, for example, by a hydraulic adjusting device. This hydraulic adjusting device has in particular a hydraulic fluid and can be arranged outside the housing, but is preferably at least partially or even completely integrated into the housing. Further, a sealing ring may be provided which seals the outer circumferential surface of the piston relative to the housing inner wall.

The hydraulic adjusting device may be provided with a surge tank, which is filled in particular with hydraulic fluid and serves, for example, to compensate for leakage losses and / or to equalize temperature-induced volume fluctuations of the hydraulic fluid in the hydraulic adjusting device. Also, this expansion tank can be integrated into the housing and is closed in particular with an elastic element or with an elastic cover. A displacement of the body or piston by means of the preferably hydraulic adjusting device has the advantage that wear of the bearing shell and possibly resulting therefrom, undesirably large clearance of the journal in the bearing shell can be compensated. Further, by means of the hydraulic adjusting a predetermined working torque for the bearing pin set and even at

Wear of the bearing shell maintained or tracked. Thus, a backlash of the joint is maintained even with wear of the bearing shell.

In addition, a force sensor and / or pressure sensor may be provided in the joint, so that a regulation of the hydraulic adjusting device, for example for the

Tracking the working torque, is feasible. The pressure sensor is preferably integrated in the hydraulic circuit, whereas the force sensor can sit between the bearing shell and the joint housing.

The combination of displaceable body or piston with hydraulic

Adjustment device also has the advantage that a leakage in the hydraulic circuit usually does not entail immediate damage to the bearing shell, so that the joint remains functional at least temporarily even in the event of a loss of hydraulic fluid and behaves like a conventional, passive joint (failing). Saife property of the hinge according to the invention).

Between the piston and the housing, an elastic membrane may be provided, via which engages the hydraulic adjusting device to the piston. The membrane preferably extends on the side facing away from the bearing shell of the piston and is, for example, sealingly fixed to the housing, so that it is possible to dispense with a sealing ring which seals the outer circumferential surface of the piston relative to the housing inner wall.

The hydraulic adjusting device may comprise a hydraulic fluid and one or more hydraulic paths or lines, which are in particular provided with one or more valves, such as non-return valves and / or solenoid valves. Preferably, however, the hydraulic adjusting device has a rheological, for example, electro-or magnetorheological hydraulic fluid as hydraulic fluid, wherein at least one hydraulic line is traversed by a particular variable electric or magnetic field. Thus, it is possible to use the hydraulic line flooded by the electric or magnetic field as a valve, wherein the toughness of the hydraulic fluid is controlled in response to the electric or magnetic field. Such a valve is also referred to as Rheo valve.

The hydraulic adjusting device may have a hydraulic pump, which is preferably arranged in the housing and may be formed, for example, as a piezo-diaphragm pump. But it is also possible to provide the hydraulic pump outside the housing.

Additionally or alternatively, the hydraulic adjusting device can be arranged on or in the housing electric motor and arranged in a hydraulic chamber

Have primary piston which is displaceable by the electric motor. This particular designed as a stepper motor electric motor can linearly adjust the primary piston via a gear and thus control the pressure in the hydraulic chamber for adjusting the piston or the clamping means. The electric motor is thus formed as a linear actuator of which, for example, a threaded spindle is rotated, which is either linearly displaced due to the rotation itself or sitting on the threaded spindle element, such as

Example a nut, linearly shifted.

The invention will be described below with reference to preferred embodiments with reference to the drawing. In the drawing show:

1 is a sectional view of a ball joint according to the invention, in which four embodiments are shown schematically,

2 is a sectional view through a ball joint according to a fifth embodiment of the invention, 3 is a sectional view through a ball joint according to a sixth embodiment of the invention,

4 is another sectional view of the embodiment of FIG. 3,

5 is a schematic representation of the hydraulic adjusting device of the embodiment of FIG. 3,

6 is a sectional view through a seventh embodiment of the joint according to the invention,

7 is another sectional view of the embodiment of FIG. 6,

Fig. 8 shows a first modification of the joint according to Fig. 3 and

9 shows a second modification of the joint according to FIG. 3.

From Fig. 1 is a sectional view through a hinge according to the invention can be seen, wherein four embodiments are shown simultaneously and the joint is designed as a ball joint. A bearing pin or ball stud 3 having a joint ball 1 and a journal region 2 is rotatably and pivotably mounted to the joint ball or bearing region 1 in a one-piece bearing shell 4. The bearing shell 4 is seated in a housing 5 which has an opening 6 through which the ball stud 3 extends. The housing 5 has one of the opening 6 opposite

Opening 7, which is closed by a cover 8. In the region of the opening 6, a sealing bellows 9 is fixed on the housing 5 by means of clamping rings 10, the end 6 facing away from the opening 1 1 sealingly abuts against the pin portion 2. In the housing 5, a recess 12 is provided, which is bounded by an inner wall 13 of the housing 5. The inner wall 13 has a cylindrical inner wall portion 14 and a tapered, in particular conical inner wall portion 15, which adjoins the Inner wall region 14 connects. The inner wall region 15 tapers with decreasing distance to the opening 6. The bearing shell 4 rests with its outer circumferential surface 16 on the two inner wall regions 14 and 15, so that the bearing shell 4 has a cylindrical outer peripheral surface region 17 lying against the inner wall region 14 and one on the inner wall region 15 adjacent, tapered, in particular conical outer peripheral surface area 18 has. The outer peripheral surface area 18 tapers with decreasing distance from the opening 6. The longitudinal axis 19 of the generally designated ball joint 20 coincides with the longitudinal axis 21 in the undeflected state of the ball stud 3.

According to a first embodiment of the invention, a preferably annular clamping means 22 between the bearing shell 4 and the cover 8 with the interposition of a support ring 23 is arranged. The clamping means 22 rests with a surface region 24 on an outer surface region 25 of the bearing shell 4, the support ring 23 being arranged between the tensioning means 22 and the cover 8. The tensioning means 22 is here designed, for example, as an electrically controlled, piezoelectric actuator which can deform the bearing shell 4 parallel to the longitudinal axis 19 by means of a change in length. As a result, the force exerted by the bearing shell 4 on the ball joint 1 mechanical tension is changed, so that the torque required for pivoting the ball pin 3 via a change in length of the clamping element or via a change in the voltage applied thereto is adjustable. The surface region 24 and the outer surface region 25 in this case run perpendicular to the longitudinal axis 19 and are in particular formed as annular surfaces.

According to a second embodiment, a preferably annular clamping means 26 is provided instead of the clamping means 22, which is arranged between the support ring 23 and the bearing shell 4 and rests with a surface region 27 on an outer surface region 28 of the bearing shell 4. The surface region 27 and the outer surface region 28 are formed conically or frustoconical and close in extension with the longitudinal axis 19 an angle α with 0 ° <α <90 °. By the oblique or conical design of the two surfaces 27 and 28, a more effective power transmission in particular to the center M of the ball 1 is achieved. Preferably, the angle α here is 30 °, so that the opening angle of the cone is 60 °. According to one alternative, however, the angle α is for example 60 °. Also, the clamping means 26 may be formed as a controllable via an electrical voltage piezoelectric actuator, which deform the bearing shell 4 parallel to the longitudinal axis 19 via a change in length and thus can change the exerted by the bearing shell 4 on the ball joint 1 mechanical tension. The second embodiment forms in particular an alternative to the first embodiment.

According to a third embodiment, a clamping element 29 is additionally or alternatively provided to the clamping means 22 or 26, which is arranged in the radial direction between the bearing shell 4 and the inner wall 13 of the housing 5. The clamping means 29 is seated in a recess 30 of the bearing shell 4, but may alternatively also be arranged in a recess formed in the inner wall 13. With the aid of the tensioning means 29, it is possible to build up a tension which acts primarily on the ball joint 1 in the radial direction, whereby a radial direction is to be understood here which runs perpendicular to the longitudinal axis 19 and preferably intersects the center M of the ball joint 1. The tensioning means 29 can be designed as a controllable via an electrical voltage piezoelectric actuator, which deform over a change in length in the radial direction, the bearing shell 4 and thus can change the force exerted by the bearing shell 4 on the ball joint 1 mechanical tension.

According to a fourth embodiment, in addition or as an alternative to the previous embodiments, the bearing shell can be made completely or at least partially of an electrically deformable composite material 31, which consists, for example, of plastic with piezoceramic fibers or carbon nanotubes embedded therein and forming a tensioning means. By applying an electrical voltage to the bearing shell 4, a deformation or volume change thereof can be brought about, resulting in a change of the bearing shell 4 on the joint ball. 1 exerted mechanical stress leads. Thus, the bearing shell 4 itself forms an actuator.

In the first four embodiments, the influencing of the torque is actively controlled, wherein a particular electrically controllable actuator is used as the clamping means. By a change in length or expansion of the actuator, a force is exerted on the bearing shell 4 and thus on the joint ball 1, whereby the movement moment of the ball joint 20 can be increased or decreased. The actuator consists for example of piezoceramic, plastic such as an electroactive polymer, carbon compounds, such as carbon nanotubes

(Carbon nano-tube) or a composite material, which is composed for example of a combination of the aforementioned materials.

Since the torques of the ball joint 20 can be actively varied via the tensioning means or means, unwanted vibrations which arise in certain driving situations on the wheel of a motor vehicle can be damped in the ball joint 20. Thus, these vibrations no longer penetrate or only subdued into the vehicle interior. It is also possible to compensate for wear of the ball joint 20, which occurs over its life and can lead to a free play and thus to noise.

From Fig. 2, a fifth embodiment of the joint according to the invention can be seen, to the previous embodiments identical or similar features are denoted by the same reference numerals as in the previous embodiments. The housing 5 is closed on the opposite side of the opening 6 by a bottom 32, which is formed here in one piece with the housing 5. Between the bottom 32 and the bearing shell 4, a clamping means 33 is provided, which is designed as a parallel to the longitudinal axis 19 displaceable piston whose outer peripheral surface 34 is displaceably guided on the inner wall 13 of the housing 5. In the outer peripheral surface 34, an annular groove 35 is provided, in which a sealing ring 36 is seated, which seals the piston 33 against the inner wall 13. Between the Piston 33 and the bottom 32, a hydraulic chamber 37 is formed, which is connected via a connection 38 and a hydraulic line 39 with a outside of the housing 5 arranged hydraulic adjusting device 40. The hydraulic line 39 and the hydraulic adjusting device 40 are shown only schematically.

A hydraulic fluid 41 can be introduced into or out of the hydraulic chamber 37 via the hydraulic adjustment device 40, as a result of which the piston 33 can be moved along the longitudinal axis 19 towards or away from the joint ball 1. As a result, the bearing shell 4 can be deformed, which leads to a change in the pressure exerted by the bearing shell 4 on the ball joint 1 mechanical stress. Thus, via the hydraulic adjusting device 40, a change in the ball joint torque can be achieved.

The hydraulic adjusting device 40 has a hydraulic pump 43 driven by a motor 42, which is connected on the one hand to the hydraulic line 39 and on the other hand to a reservoir 44 filled with the hydraulic fluid 41. Further, a valve 45 is provided between the surge tank 44 and the hydraulic line 39.

The piston 33 has a frusto-conical surface area 46, which rests against a likewise frustoconical outer surface area 47 of the bearing shell 4. The frustoconical surface regions 46 and 47 in this case in an extension with the longitudinal axis 19 an angle α with 0 ° <α <90 °, wherein an angle of α = 30 ° has been found to be particularly suitable. According to one alternative, however, the angle α is for example 60 °. Opposite the surface region 47, the bearing shell 4 has a frustoconical outer surface region 48, which rests against a likewise frustoconical inner wall region 49 of the housing 5. The two frusto-conical regions 48 and 49, in extension with the longitudinal axis 19, form an angle β with 0 ° <β <90 °, whereby an angle of β = 30 ° has proven to be particularly suitable. According to an alternative, the angle β but to Example 60 °. The joint ball 1 or its center M is arranged between the two outer surface regions 47 and 48, wherein the outer surface region 47 and the surface region 46 are aligned such that these two regions 47, 46 taper with increasing distance from the opening 6. In contrast, the outer surface region 48 and the inner wall region 49 are aligned such that these two regions 48, 49 taper with decreasing distance from the opening 6.

The overall one-piece bearing shell 4 thus has two conical outer contours in the areas 47 and 48. Furthermore, the housing inner wall 13 is designed conically towards the opening 6 in the area 49. Also, the piston 33 is conically formed on its outer surface facing the bearing shell 4 in the region 46 or there has an inner cone, wherein all of these conical surfaces 46, 47, 48, 49 in terms of magnitude preferably have a same inclination angle α or ß to the longitudinal axis 19. With this arrangement, the disadvantages of the two-part bearing shell are eliminated in a completely cylindrical housing inner surface. By preferably 60 ° cone (46, 47, 48, 49), the ball 1 is stretched from above and from below with equal forces uniformly from the bearing shell 4 and expressed a possibly existing radial clearance. The clamping force is reinforced by the wedge effect, whereby a correspondingly increased clamping stroke can be better controlled. In addition, the system becomes much less sensitive to external axial forces. A franking 76 (see FIG. 6) at the equatorial region of the bearing shell inner surface can reinforce this effect, since then the tensioning forces act essentially only towards the center of the ball, in particular along the upper and lower approx. 30 ° degrees of longitude.

3 shows a sixth embodiment of the joint according to the invention, which is a modification of the fifth embodiment, so that identical or similar features are denoted by the same reference numerals as in the fifth embodiment. In contrast to the fifth embodiment, in the sixth embodiment, the hydraulic adjusting device is integrated in the joint housing 5, which is here formed in two parts and an upper housing part 50 and a lower housing part 51 which is attached to the upper housing part 50. The lower Housing part 51 closes one of the opening 6 opposite opening 52 of the upper housing part 50 and thus forms a housing bottom. The cooperating with the piston 33 and the hydraulic chamber 37 hydraulic adjusting device is disposed in the lower housing part 51 and will be described below.

A piezo-membrane pump 53 is seated in a recess 54 of the housing part 51 and actuates a slidably guided in the housing part 51 and extending into a hydraulic chamber 55 pump piston 56 which can be moved by the pump 53 in the direction and in the opposite direction of the arrow P, whereby the volume of Hydraulic chamber 55 is variable. If the pump piston 56 in

Direction of the arrow P, the volume of the hydraulic chamber 55 decreases so that a hydraulic fluid 57 introduced into this chamber flows through a hydraulic passage 58 into the hydraulic chamber 37. As a result, the piston 33 is displaced in the direction of the arrow Q, resulting in a deformation of the bearing shell 4 and thus an increase of the force exerted by the bearing shell 4 on the joint ball 1 mechanical

Voltage causes. In the hydraulic chamber 55, a valve 59 is provided with which a backflow of the hydraulic fluid 57 from the hydraulic chamber 37 into the hydraulic chamber 55 can be prevented. Further, a filled with the hydraulic fluid 57 expansion tank 60 is disposed in a recess 61 of the housing part 51 and closed by an elastic cover 82 which is secured via a cover 62 on the housing 5.

From Fig. 4 is a section of the sixth embodiment along the section line 79 of FIG. 3 can be seen, wherein a lying behind the hydraulic chamber 55 hydraulic chamber 63 is indicated by dashed lines. The hydraulic chamber 63 communicates via an opening 64 with the hydraulic chamber 55 and is connected via a hydraulic line 65 to the surge tank 60. Furthermore, the hydraulic chamber 63 has a valve 66, which prevents a movement of the hydraulic fluid 57 from the hydraulic chamber 55 through the opening 64, through the hydraulic chamber 63 and through the hydraulic line 65 in the compensation chamber 60 upon movement of the pump piston 56 in the direction of arrow P. can. The two valves 59 and 66 may be formed as check valves, wherein preferably designed in particular as a mini-solenoid valve additional valve 67 (see FIG. 5) and additional hydraulic paths 68, 69 (see FIG. 5) are providable, so that pressure or hydraulic fluid from the Hydraulic chamber 37 can be drained. Alternatively, however, it is also possible to use as hydraulic fluid 57 an electro- or magneto-logical fluid whose viscosity can be controlled via an electric or magnetic field. The valves 59 and 66 may then be designed as so-called "rheo-valves" and generate a magnetic or electric field which passes through channels 77 and 78, so that, depending on the strength of the field, a flow of hydraulic fluid through the channels 77 and / or 78 In this case, the additional valve 67 with the lines 68, 69 for releasing the pressure from the hydraulic chamber 37 is not required.

From Fig. 5 is a schematic view of the hydraulic adjusting or the hydraulic circuit according to the sixth embodiment can be seen, wherein the

Valves 59 and 66 are preferably designed as Rheo valves, which allow a flow of hydraulic fluid 57 in both directions. In the event that the valves 59 and 66 form only check valves, the additional valve 67 and the two additional lines 68, 69 are provided and indicated by dashed lines. The additional valve 67 is connected via the line 68 to the hydraulic chamber 37 and via the line 69 to the surge tank 60.

According to the sixth embodiment, it is proposed to integrate the pressure generation directly into the ball joint housing 5. This is feasible because there are practically no or only minor delivery volumes (max 1 cm ³ plus the

Compressibility of the pressure medium) and the necessary pressures are relatively small (<100 bar, average max 50 bar). Instead of an external arrangement of the electric motor, pump, valve and piping, a piezo membrane built into the lower housing part 51 or into the cover of the ball joint 20 is used as the pump 53. This is vibrated via an electrical voltage and pumps the standing in front of the piston 56 hydraulic fluid back and forth. Thus a pumping effect comes, the pump chamber has two connection channels or connections, one to the expansion tank 60 and the other to the hydraulic chamber 37 on the piston 33 below the bearing shell 4. In these two compounds check valves 59, 66 may be provided, the suction at each stroke of the piston 56 and allow pumping, without the fluid 57 only to push back and forth. A mini-solenoid valve 67 may be connected to the hydraulic chamber 37 to release the pressure from this chamber 37. Alternatively, however, it is also possible to use a rheological fluid as pressure medium 57, the two valves 59 and 66 being designed as rheo-valves. In this case, the connections to the expansion tank 60 and to the hydraulic chamber 37 can be controlled via electric or magnetic fields, which alternately block or release a flow of the hydraulic fluid 57 in time or in common with the vibrations of the piezoelectric membrane. The connections have very small diameters (1-3 mm) and are provided in the lower housing part 51. The piston 33, whose diameter is slightly larger than the diameter of the joint ball 1, is automatically applied to this pressure. However, since the surface of the piston 33 is about 100 times larger than the surface of the piston 56, also about 100 times greater compressive forces than the axial forces, which are still reachable by the piezoelectric effect unfold. The stroke of the piston 33 is very small (for example, a maximum of 0.3 mm), but is still sufficient to increase the force exerted by the bearing shell 4 on the ball joint 1 such that the ball joint 1 is immovable. In the case of a theological fluid as the hydraulic fluid 57 and the provision of Rheo valves 59, 66, no additional valve 67 is required for releasing the pressure from the chamber 37, since the two channels 77 and 78 can be released for the passage of hydraulic fluid 57, by, for example, reducing or reducing the current flowing through the rheo-valves 59, 66 and used to build up the magnetic fields.

By integrating the piezo pump 53 in the ball joint housing 5 and the use of theological fluids as hydraulic fluid 57, the torque of the ball joint 20 can be continuously, in particular very sensitively controlled in any position. The oscillation frequencies of the piezo pump 53 can be selected to be very high, with a synchronization between the piezo membrane and the two theological ones Valves 59, 66 is easily possible. The efficiency is very high and the runtimes because of the high frequency very small. In addition, the piezo membrane can be used to measure the pressure and be used, for example, in a control loop as a pressure sensor.

FIG. 6 shows a seventh embodiment of the joint according to the invention, which represents a development of the fifth embodiment, wherein the hydraulic adjusting device is integrated in the ball joint housing 5. In particular, the seventh embodiment represents an alternative to the sixth embodiment, wherein identical or similar features are denoted by the same reference numerals as in the fifth and sixth embodiments.

The housing 5 has an upper housing part 50 and a lower housing part 51, which is fixed to the upper housing part 50. In the lower housing part 51, a hydraulic chamber 55 is formed, which via a hydraulic line 58 with the

Hydraulic chamber 37 is connected below the piston 33. In the hydraulic chamber 55, a primary piston 56 is displaceably guided in the direction and in the opposite direction of the arrow P, so that by a movement of the primary piston 56, the volume of the hydraulic chamber 55 is variable. In the hydraulic chamber 55, a hydraulic fluid 57 is provided, which flows in the direction of the arrow P in the direction of arrow P in the direction of arrow P through the hydraulic line 58 into the hydraulic chamber 37 and raises the piston 33 in the direction of arrow Q. The primary piston 56 has an annular groove 70, in which a sealing ring 71 is seated, which seals the primary piston 56 with respect to the inner wall of the hydraulic chamber 55. The primary piston 56 is connected via a gear 72 with an electric motor 73, which is fixed to the lower housing part 51. The motor 73 is designed, in particular, as an electric stepping motor, which can push a linear spindle 75, which is connected to the primary piston 56. Further, in a recess 61 of the lower housing part 51 a filled with hydraulic fluid 57 and sealed with an elastic cover 82 reservoir 60 is provided, which is secured by a bracket 62 to the lower housing part 51. Of the

Expansion tank 60 is connected via a channel 74 with the hydraulic chamber 55, wherein depending on the position of the primary piston 56, the channel 74 can be opened or closed. In the open state, the channel 74 forms a hydraulic connection between the surge tank 60 and the filled with hydraulic fluid 57 volume of the hydraulic chamber 55. In the closed state of the channel 74, this hydraulic connection is interrupted.

As in the sixth embodiment, according to the seventh embodiment, the pressure generation is integrated directly into the ball joint housing 5, which is feasible for the same reasons as in the sixth embodiment. In particular, it is possible to provide a small stepping motor 73 with integrated linear spindle 75, which can push the primary piston 56 back and forth in the direction and in the opposite direction of the arrow P. Such a stepping motor 73 with a linear spindle 75 can be obtained inexpensively as a commodity.

The primary piston 56 preferably has a small diameter of 3 - 5 mm, which sits in the hydraulic chamber or bore 55 in the lower housing part 51. The primary piston 56 has in particular a stroke of 15-30 mm. The bore 55 is connected via the channel 58 to the chamber 37 and thus to the piston 33. The secondary piston 33, whose diameter is slightly larger than the diameter of the joint ball 1, is automatically pressurized with the same pressure. However, since the surface of the secondary piston is about 100 times larger than the area of the primary piston 56, about 100 times greater pressure forces unfold. Although the stroke of the secondary piston 33 is about 100 times smaller than the stroke of the primary piston 56, this is still sufficient to increase the torque or the friction torque of the ball joint 20 to immobility. To lower the pressure in the hydraulic chamber 37 no valve is required. The lowering of the pressure is achieved by the stepping motor 73 being rotated backwards, which leads to a movement of the primary piston 56 in the opposite direction of the arrow P. The compensation chamber 60 is included in the retracted position of the primary piston 56 in the hydraulic circuit, and is only used to compensate for leakage losses and temperature-dependent pressure fluctuations. Under the retracted position while a position is understood in which the Primary piston 56 is shifted so far in the opposite direction of the arrow P until a hydraulic connection between the surge tank 60 and the volume of the hydraulic chamber 55 is formed via the channel 74.

Compared to the fifth and sixth embodiments, valves and

Pressure sensors are eliminated. Furthermore, a reduction of the required lines and fittings can be achieved. The torque of the ball joint 20 can be infinitely, very sensitively controlled in any position. The efficiency losses are very low, although a hundredfold gain can be achieved effortlessly. The integration of the hydraulic circuit in the ball joint 20 reduces the amount of pressure medium required to a minimum, in particular to the necessary compensation of the compressibility of the pressure medium.

FIG. 7 shows a sectional view of the embodiment according to FIG. 6 along the section line 79, from which the structure simplified in comparison with the sixth embodiment becomes clear.

Figs. 8 and 9 show modifications of the embodiment of Fig. 3, wherein identical and similar features are denoted by the same reference numerals as in the sixth embodiment. Between the piston 33 arranged in the upper housing part 50 and the lower housing part 51 or the housing bottom, an elastic membrane 80 is provided, so that the hydraulic chamber 37 accessible via the hydraulic channel 58 is formed between the membrane 80 and the housing bottom 51. When the hydraulic chamber 37 is supplied with hydraulic fluid 57 via the hydraulic passage 58, the diaphragm 80 expands and presses the piston 33 in the direction of

Arrow Q. The elastic membrane 80 is preferably sealingly fixed to the housing 5, so that can be dispensed with in these modifications to the apparent from Fig. 3 sealing ring 36 for sealing the piston 33 relative to the Gehäuseinnenwandung 13. Further, the membrane 80 can extend into the region between the outer peripheral surface 34 of the piston 33 and the housing Eineinungung 13. According to the first modification shown in FIG. 8, the membrane 80 is fastened in an annular groove 81 provided in the inner wall 13 of the housing 5. Alternatively, however, the membrane 80 can also be fixed, in particular clamped, between the upper housing part 50 and the lower housing part 51, as can be seen in FIG. 9.

Furthermore, according to FIG. 9, a force sensor 83 is arranged between the bearing shell 4 and the housing 5, which delivers a signal which represents the current mechanical stress which is exerted by the bearing shell 4 on the joint ball 1. The force sensor 83 thus opens up a possibility of a regulation for the hydraulic

Adjustment to realize. Alternatively, the force sensor can also be designed as a pressure sensor and integrated, for example, in the hydraulic circuit. The pressure sensor sits for this purpose, for example, in the hydraulic chamber 55 or is formed by the piezo-membrane of the pump 53.

Although these modifications have been explained as developments of the sixth embodiment, it is possible to provide in the other embodiments, an elastic membrane between the piston 33 and housing bottom 32 and 51, so that even there can be dispensed with the sealing ring 36. Furthermore, the use of a force or pressure sensor in all embodiments is possible.

LIST OF REFERENCE NUMBERS

Ball joint Journal area Spigot / Spigot Bearing shell Housing Opening in housing Opening in housing Cover Sealing bellows Clamping rings End of sealing bellows Housing recess Inner wall of housing Cylindrical inner wall area Tapered inner wall area Outer circumferential surface of bearing shell Cylindrical outer peripheral surface area of bearing shell Tapered outer peripheral surface area of bearing shell Longitudinal axis of ball joint Ball joint Longitudinal axis of ball stud Clamping means Support ring Area of the clamping device Outer surface area of the bearing shell Clamping means Surface area of the clamping device Outer surface area of the bearing shell Clamping area Area of the composite bearing shell Body bottom Clamping means / piston Outer circumference of the piston Ring groove Sealing ring Hydraulic chamber Hydraulic fluid connection Hydraulic fluid Motor Hydraulic pump Expansion reservoir Valve frusto-conical area of the piston frusto-conical outer surface of the bearing frusto-conical outer surface of the bearing frusto-conical interior area of the housing Upper part of the housing Lower part of the housing Case opening Pump recess in lower housing part hydraulic chamber pump piston / primary piston hydraulic fluid hydraulic passage valve 0 Expansion tank or chamber 1 Recess in lower housing part 2 Lid / holder 3 Hydraulic chamber 4 Opening in hydraulic chamber 5 Hydraulic line 6 Valve 7 Additional valve 8 Additional hydraulic line 9 Additional hydraulic line 0 Ring groove 1 Sealing ring 2 Gearbox 3 Motor 4 Channel 5 Linear spindle 6 Clearance 7 channel 8 channel 9 line 0 elastic membrane 1 groove in housing 2 elastic cover 3 force or pressure sensor α angle ß angle

M Center point of the joint ball

P arrow

O arrow

Claims

Joint for a motor vehicle patent claims

A joint for a motor vehicle, comprising a housing (5), a bearing shell (4) arranged in the housing (5), a bearing journal (3) having a bearing area (1) and a journal area (2) which is in contact with the bearing area (3). 1) in the bearing shell (4) is pivotally and / or rotatably mounted and at least one in the housing (5) arranged and designed as a solid clamping means (33), of which one of the bearing shell (4) on the bearing area (1) exerted mechanical stress is variable, characterized in that

- The bearing shell (4) formed at least partially resilient and from the clamping means (33) is elastically deformable.

2. Joint according to claim 1, characterized in that the clamping means (33) outside the bearing shell (4) is arranged and on a first outer surface region (47) of the bearing shell (4) engages.

3. Joint according to claim 2, characterized in that the first outer surface region (47) is frusto-conical.

4. Joint according to claim 2 or 3, characterized in that the clamping means (33) has at least a frusto-conical surface region (46) and acts on this on the first outer surface region (47).

5. Joint according to claim 3 or 4, characterized in that the bearing shell (4) is provided with a second frusto-conical outer surface region (48), wherein the housing (5) has an inner wall (13) with a frusto-conical shape formed inner wall portion (49) on which abuts the second outer surface region (48).

6. Joint according to claim 5, characterized in that the two frustoconical outer surface regions (47, 48) of the bearing shell (4) taper with increasing distance from each other.

7. Joint according to claim 5 or 6, characterized in that the bearing region (1) at least partially between the two outer surface regions (47, 48) of the bearing shell (4) is arranged.

8. Joint according to one of the preceding claims, characterized in that the clamping means (22, 26, 29, 31) comprises carbon nanotubes or a piezoelectric, electrostrictive or magnetostrictive material.

9. Joint according to one of the preceding claims, characterized in that the clamping means (33) in the housing (5) displaceably mounted piston.

10. Joint according to claim 9, characterized in that in the housing (5), a hydraulic adjusting device is at least partially disposed, from which the piston (33) in the housing (5) is displaceable.

11. Joint according to claim 10, characterized in that the hydraulic adjusting device has an electro- or magnetorheological hydraulic fluid (57) and at least one hydraulic line (77) which is traversed by an electric or magnetic field.

12. Joint according to claim 10 or 11, characterized in that the hydraulic adjusting device has a on or in the housing (5) arranged hydraulic pump (53).

13. Joint according to one of claims 10 to 12, characterized in that the hydraulic adjusting device on or in the housing (5) arranged electric motor (73) and a primary piston (56) which is displaceable by the motor (73) ,

14. Joint according to one of claims 10 to 13, characterized in that between the piston (33) and the housing (5) an elastic membrane (80) is arranged.

15. Joint according to one of claims 10 to 14, characterized in that the hydraulic adjusting device has a in the housing (5) integrated surge tank.

16. Joint according to claim 15, characterized in that the expansion tank (60) has an elastic cover (82).

17. Joint according to one of claims 10 to 16, characterized in that the hydraulic adjusting device is completely integrated in the joint.

18. Joint according to one of the preceding claims, characterized in that the joint is a ball joint (20) and the joint area is a joint ball (1).

19. Joint according to one of the preceding claims, characterized in that the bearing shell (4) is integrally formed.

20. Joint according to one of the preceding claims, characterized in that in the housing (5), a pressure sensor and / or a force sensor (83) is provided.