DE102004009725A1 - Clutch mechanism for steering column adjustment device, comprises rotor and stator separated by space containing rheological fluid with adjustable viscosity - Google Patents

Abstract

The mechanism (1) comprises a rotor (3) and stator (2) separated by at least one intermediate space (4) containing a rheologically active substance (e.g. rheological fluid). A means (7) is provided for generating a magnetic and/or electric field in the intermediate space in order to alter the viscosity of the active substance and therefore the level of traction between the rotor and stator. A solenoid, two or more rotary or sliding permanent magnets or a capacitor are used to alter the viscosity of the active substance.

Description

The The invention relates to a coupling mechanism between two relatively rotatable components, preferably for use in a steering column adjustment.

Such Couplings are generally used to pass on torques between aligned and non-aligned waves, for example as Connection between a power train of an engine and a subsequent drive train of a machine or as a connection between an adjusting spindle of a steering column adjustment and the drive motor. Examples of such couplings are the groups mechanical, hydraulic or electromagnetic couplings.

The hydraulic couplings have the advantage that the power transmission, due to the liquid Medium, which the forces transmits between the drive and output line, are relatively variable. Such hydraulic clutches are for example as a torque converter known in automatic transmissions in motor vehicles. Unfortunately arises in such couplings without direct mechanical bridging a certain slip between drive and driven side and their construction is relatively expensive. For mechanical couplings, it is advantageous that a form-fitting adhesion between the drive and Output train is achieved, allowing a nearly lossless power transmission is possible. However, a coupling or decoupling of such mechanical couplings only feasible with relatively high design effort, also result wear problems in the known variable couplings.

It The object of the invention is to find a coupling mechanism on the one hand the variability a hydraulic clutch and on the other hand, however easy way the complete frictional torque transmission offers. In particular, this invention is intended for use in steering column adjustment be usable.

These The object is solved by the features of the independent claims. advantageous Embodiments are set forth in the subclaims.

The Inventors have recognized that the use of a magneto or electro-rheological fluid in a clutch mechanism it allows, in a simple way, namely by simply turning on and off a magnetic or electrical Feldes, the power transmission to influence between two shafts by a clutch mechanism is formed, which is the only connecting element between a rotor and a stator a rheologically active liquid used. This can be done by turning on and off a magnetic or electric field, the viscosity of this rheological fluid drastically changed be chosen so that when low viscosity only a minimal power transmission takes place while when setting a high viscosity, which in extreme cases too a change of state from liquid too tight, almost a form-fitting Connection between drive and output side is made possible.

Advantageous Here is also that change the power transmission situation without any mechanical adjustment is possible and thus on mechanical wear parts can largely be dispensed with.

Corresponding this idea underlying the invention, beat the Inventor a coupling mechanism for variable positive connection between two relatively rotatable components before, consisting a stator and a rotatable rotor relative to the stator, wherein stator and rotor form at least one space, in which is a rheologically active substance, wherein further Means for generating a magnetic and / or electric field arranged in the at least one intermediate space between the stator and the rotor are what the viscosity the rheologically active substance and thus the adhesion between Change rotor and stator depending on field condition. In this context It should be noted that under a rheologically active liquid For the purposes of the invention, only liquids are to be understood, their viscosity due to an applied electric or magnetic field change significantly. Not Under it are to be understood substances, whose viscosity exclusively due to variable pressure and changeable Temperature varies. To be taken into account magneto and Electro-rheological substances also include substance mixtures and suspensions, for example, by the use of so-called Nano-particles the desired electro- or magneto-rheological Get properties.

The preferred field of application of the clutch mechanism according to the invention is in the field of vehicle technology, in particular in the field of steering technology. Thus, the coupling mechanism according to the invention can be used particularly advantageously for a steering column adjustment. Such a steering column adjustment is for example from the on applicant filed patent application DE 196 41 152 A1 known. The disclosure of this patent is incorporated in full. This patent discloses a longitudinal and incline adjustable motor vehicle steering column assembly which achieves both longitudinal and pitch adjustment with a single motor. For this purpose, it is necessary in this embodiment, via axially movable mounted spindle nuts alternately ent neither the adjustment mechanism for the longitudinal direction or the adjustment mechanism for the inclination adjustment with the drive unit to couple to drive these different adjustment mechanisms separately.

at Such steering column adjustment is it is therefore necessary, as possible variable coupling between an adjusting motor and one or more To achieve drive spindles for adjusting the steering column, where possible largely to mechanically moving parts within the clutch mechanism should be waived. Due to the inventive design of such a coupling mechanism, the power transmission effect only by switching on and off an electrical or magnetic field and the consequent change in viscosity a rheologically active in the coupling device Substance changes, let yourself Such a coupling unit between the drive motor of a steering column adjustment and the adjusting spindle attached there, the longitudinal adjustment or also achieved a tilt adjustment, use particularly well.

In an embodiment variant the coupling mechanism according to the invention Stator and rotor can be designed such that between them at least one annular gap is formed, which preferably also with on and Bulges is equipped. Such an annular gap arises, for example through the meshing two substantially cylindrical stator and rotor units. Become additional on the surfaces the cylindrical components formed indentations and bulges, so arises at high viscosity the rheologically active substance is a particularly good adhesion between rotor and stator. Of course it is also in the frame of the invention, when between rotor and stator not just a single but several nested annular gaps arise, so that the total through the rheologically active liquid wetted surface and thus also the power transmissions be enlarged.

Next the design of the gap between the stator and the rotor as Annular gap, there is also the possibility Perform stator and rotor in such a way that the space between them is disc-shaped, wherein also in this form of training on the delimiting areas of the Interspaces bulges and bulges may be appropriate to to achieve a better friction between stator and rotor.

In a particular embodiment can the at least one interior space between the rotor and stator a housing outward be sealed, so that the rheologically active substance is not after Outside can get.

According to the invention of Clutch mechanism be designed so that the rheologically active Substance receives direct contact with the surfaces of rotor and stator and thus also the adhesive properties between the surfaces of rotor and stator on the one hand and the rheologically active substance, on the other hand, in power transmission play. The coupling mechanism according to the invention However, it can also be designed so that the rheologically active Substance no direct contact with the surfaces of Rotor and stator receives and in a flexible sheath or flexible hose in the space located by rotor and stator. It is rotor and stator with additional Indentations and bulges provided so that at high viscosity, if necessary even a transition in the solid state of rheologically active substance, a positive connection between rotor and stator is achieved. Basically, this embodiment corresponds a kind of self-contained peristaltic pump. In this pump becomes the rheologically active substance in a closed tube pumped all around. By creating a field increases the viscosity if necessary until the change of the state of aggregation and increased thus the resistance between rotor and stator.

at this embodiment with a peristaltic tube, it may be advantageous if the Bulges of the rotor or stator have additional rolling elements, AS POSSIBLE low friction between the bulges and the wall of the tube or flexible sheath arises. Such a design has the advantage that the interior space between the rotor and stator is not special must be sealed and still the rheologically active substance not outward can penetrate.

For generating the magnetic field, for example, serve a switchable electromagnet or it can also be provided two mutually rotatable or displaceable permanent magnets, depending on their orientation, the field in the rheological fluid amplify or weaken and thus the viscosity of the rheo change logically active substance.

is it is necessary for change the viscosity the rheologically active substance to build up an electric field, For example, this electric field with the help of a capacitor, for example by a plate capacitor, the rheological active substance then in the intermediate area between the capacitor plates should be arranged.

Around one possible to achieve high efficiency of the generated magnetic field, can advantageously the stator and / or the rotor and / or the housing be made of non-magnetizable material. Preferably this may be plastic.

It It should be noted that the terms rotor and stator only describe that in the frame of reference of the stator in which this naturally static is, the rotor is rotated relative thereto. Becomes another frame of reference selected so can both rotor and stator are in rotating motion.

It is further noted that under a rheologically active Substance is understood as a medium which by applying a magnetic or electric field its viscosity in the range of several millipascal seconds Change [mPa s] can. Not to be understood by it are substances whose viscosity is in the essential only due to variable environmental conditions, such as Temperature and pressure, changes.

additional Features and advantages of the invention will become apparent from the following Description of preferred embodiments with reference to the drawings.

The Invention will be explained in more detail with reference to the drawings. They show:

1 : Coupling mechanism with rheological fluid;

2 : Peristaltic pump type clutch mechanism;

3 : Application example of the coupling mechanism according to the invention on a steering column adjustment device.

The 1 shows a first embodiment of a coupling mechanism according to the invention 1 with a controlled rheological fluid. In the illustrated example is located within a coupling housing 2 , which acts as a stator and on the inside with indentations and bulges 9 is provided, a spindle nut 3 , which also on its outside with indentations and bulges 9 is provided. The spindle nut 3 sits on an axis 6 , which is mounted rotatably together with the spindle nut. Between spindle nut 3 and coupling housing 2 creates a gap in this way 4 , in which a rheologically active liquid is incorporated, depending on the viscosity state of the rheologically active liquid, a more or less strong coupling between the spindle nut and the clutch housing comes about. Due to the structured inner wall of the coupling housing with indentations and bulges 9 and the opposite outer wall of the spindle nut 3 , which is also provided with sawtooth-like indentations and bulges, can be transmitted by the rheological fluid particularly good torque between the spindle nut and coupling housing, as this structure "slipping" of the housing inner wall or the outer wall of the spindle nut against the rheologically active liquid is difficult ,

To control the rheologically active liquid is a mounted on the clutch housing solenoid 7 which internally has an electrically operated coil, the electrically controlled a magnetic field within the intermediate space 4 can switch on and off, so that in this way the viscosity of the rheologically active liquid can be changed in the desired manner.

A similar embodiment of a clutch mechanism 1 is in the 2 shown. This also shows a clutch housing 2 , which acts as a stator and is provided on the inside with rounded indentations and bulges. Concentric to the coupling housing 2 is an axis 6 provided on the turn, a spindle nut 3 is located, taking on the spindle nut 3 at two opposite side or possibly also at several, as symmetrically distributed, job roles 8th are attached. These roles 8th are above the radius of the spindle nut 3 and press into a circulating tube filled with rheologically active fluid to create a peristaltic pump-like function. Will the spindle nut 3 with the attached roles 8th rotates, so there is a circulating transport of the rheologically active liquid within the circulating hose. At low viscosity of the liquid, this transport can be done almost without resistance, but at high viscosity of the rheologically active liquid generates a correspondingly high resistance and a strong coupling between the acting as a rotor spindle nut 3 and acting as a stator clutch housing 2 generated. By varying the field strength can be change the viscosity steplessly and thus also adjust the coupling steplessly. Controlled is the viscosity of the rheologically active liquid within the tube 5 by a switching magnet attached to the housing 7 , which can drastically change the adhesion forces within the rheologically active liquid by switching on and off the switching magnet, or can vary by regulating the magnet.

Although the coupling mechanism according to the invention can be used in many application examples, however, is a particularly preferred application example in the 3 shown. This shows a per se known Längssäulenverstelleinrichtung a motor vehicle in a side view. By way of example, the coupling mechanisms according to the invention can be attached to the positions designated by A and B in order to provide, via the coupling mechanisms provided there for a spindle drive, an electrically controlled torque transmission between the inner spindle 6 and to produce the outer casing. Well recognizable here are the two solenoids 7 which are arranged on the outside of the housing.

It it is understood that the above features of the invention not only in the specified combination, but also in others Combinations or alone, without the frame to leave the invention. Likewise, it is within the scope of the invention mechanical reversal of the functions of the individual mechanical elements to effect the invention.

All in all So is by the invention, with respect to its torque transmission variably adjustable, coupling mechanism between two relative proposed to each other rotatable components, in which the strength of the Coupling between the rotating components by using a rheological active substance and a variable Field is determined.

1

clutch mechanism

2

Stator / clutch housing

3

Rotor / spindle nut

4

gap with rheological fluid

5

tube with rheologically active liquid in the space

6

Spindle / axle

7

switching magnet with coil

8th

role

9

Input / convexities

Claims (9)

Clutch mechanism ( 1 ) for the variable frictional connection between two relatively rotatable components ( 2 . 3 ), preferably for a steering column adjustment device, consisting of a stator and a rotatable relative to the stator rotor ( 3 ), where Stator ( 2 ) and rotor ( 3 ) at least one space ( 4 ) in which there is a rheologically active substance, wherein furthermore means for generating a magnetic and / or electric field ( 7 ) in the at least one intermediate space ( 4 ) between stator ( 2 ) and rotor ( 3 ) are arranged, which determines the viscosity of the rheologically active substance and thus the adhesion between the rotor ( 3 ) and stator ( 2 ) depending on field status. Clutch mechanism according to the preceding claim 1, characterized in that the at least one intermediate space ( 4 ) between stator ( 2 ) and rotor ( 3 ) as an annular gap ( 4 ), preferably with indentations and bulges. Clutch mechanism according to the preceding claim 1, characterized in that the at least one intermediate space ( 4 ) between stator ( 2 ) and rotor ( 3 ) disc-shaped, preferably with indentations and bulges ( 9 ), is trained. Clutch mechanism according to one of the preceding claims 1 to 3 , characterized in that the at least one interior ( 4 ) by a housing ( 2 ) is sealed to the outside. Clutch mechanism according to one of the preceding claims 1 to 4 , characterized in that the rheologically active substance is surrounded by a flexible sheath or hose. Clutch mechanism according to one of the preceding claims 1 to 5 , characterized in that a switchable electromagnet ( 7 ) is provided for the variable generation of a magnetic field. Clutch mechanism according to one of the preceding claims 1 to 6 , characterized in that at least two mutually rotatable or displaceable permanent magnets are provided, which can strengthen or weaken the field in the rheological fluid due to their orientation. Clutch mechanism according to one of the preceding claims 1 to 7 , thereby ge indicates that a capacitor is provided for the variable generation of an electric field. Clutch mechanism according to one of the preceding claims 1 to 8th , characterized in that stator ( 2 ) and / or rotor ( 3 ) and / or housing made of non-magnetizable material, preferably made of plastic.