WO2020229009A1

WO2020229009A1 - Assembled three-point link

Info

Publication number: WO2020229009A1
Application number: PCT/EP2020/055791
Authority: WO
Inventors: Andre Stieglitz; Ingolf Müller
Original assignee: Zf Friedrichshafen Ag
Priority date: 2019-05-10
Filing date: 2020-03-05
Publication date: 2020-11-19
Also published as: DE102019206792A1

Abstract

The invention relates to a three-point link (6), which is designed as an assembly three-point link for guiding a rigid axle (5) of a utility vehicle (1). The three-point link (6) has a first link arm (7) and a second link arm (8), the two link arms (7, 8) being arranged in a V shape at an acute angle in relation to one another and meeting at a central joint (9). The central joint (9) is designed as an elastomer joint and has a housing (18) having a preloaded rubber-elastic interlay (21) arranged therein. The invention is characterized in that the housing (18) consists of a light metal and the preloaded rubber-elastic interlay (21) is surrounded by a steel bush (22), which absorbs peripheral stresses resulting from the preloading of the rubber-elastic interlay (21) such that the housing (18) of the central joint (9) has to absorb only pure chassis forces during driving operation.

Description

Built three-point link

The invention relates to an assembled three-point link for guiding a rigid axle of a commercial vehicle according to the preamble of claim 1.

Built three-point control arms for guiding rigid commercial vehicle axles are known from the prior art. When installed in a utility vehicle, three-point control arms of this type are generally arranged in the center of the vehicle with respect to a transverse direction of the vehicle. In relation to a vertical direction of the vehicle, the three-point link are usually located in an upper link plane. In a lower steering level, the rigid axle can be guided by one axle strut on each side of the vehicle.

From DE 10 2009 026 739 A1 a built three-point link is known which has a first link arm and a second link arm, the two link arms being arranged in a V-shape at an acute angle to one another and meeting in a joint arrangement, which also acts as a central joint referred to as. The Zentralge steering, which is designed as an elastomeric joint, has a housing with a pretensioned rubber-elastic intermediate layer made of a rubber material arranged therein. Preloading rubber-elastic intermediate layers in elastomeric joints is common practice in order to reduce or completely eliminate production-related tensile stresses in the rubber material. Such tensile stresses arise as a result of the load and / or as a result of the production process, for example through cooling after vulcanization.

Known from the prior art three-point link, in particular those for Füh tion of commercial vehicle rigid axles, consist of a ferrous material, in particular steel - apart from some joint components. At the same time, the commercial vehicle industry is increasingly looking for solutions to achieve weight reductions through lightweight construction. Reductions in mass lead to an increase in the payload; that is, the load that a transport vehicle can take as cargo. In addition to this economic effect, mass reductions due to reduced fuel consumption also have an ecologically positive effect. All- However, in the case of built-in three-point control arms for guiding rigid commercial vehicle axles, a lightweight design cannot be implemented simply by substituting materials.

Against this background, it is the object of the invention to provide a built Dreipunktlen ker for guiding a rigid axle of a commercial vehicle in lightweight construction, the three-point link in lightweight construction for the transmission of relatively high loads, as they usually occur on commercial vehicle rigid axles, should be suitable.

This object is achieved according to the present invention by a built three-point link with the features of independent claim 1.

Preferred embodiments and developments are the subject of the claims. Further features and details of the invention emerge from the description and from the drawing figures.

The invention accordingly provides a three-point link as a built three-point link for guiding a rigid axle of a commercial vehicle. The three-point link has a first link arm and a second link arm, the two link arms being arranged in a V-shape at an acute angle to one another and meeting in a central joint. The central joint is designed as an elastomer joint and has a housing with a pretensioned rubber-elastic intermediate layer arranged therein. According to the invention, the housing consists of a light metal. The pretensioned rubber-elastic intermediate layer is surrounded by a steel bushing that absorbs circumferential stresses which result from the pretensioning of the rubber-elastic intermediate layer, so that the housing of the central joint only has to absorb pure chassis forces in a ferry operation.

Through the steel bushing that absorbs the hoop stresses that result from the biasing of the rubber-elastic intermediate layer, the housing of the central joint is relieved and can therefore be made relatively easily from a light metal, in particular special aluminum. Without the steel bushing, the housing would be made of aluminum, for example, due to the not possible due to the material pressure. In particular, the link arms are rigidly connected to the central joint. In the present case, a rigid connection is to be understood as a connection between two parts that can in principle be separated, for example by loosening screws or by destroying a material connection, the two parts of which, however, cannot move relative to one another when used as intended . In connection with the present invention, a commercial vehicle is to be understood as a preferably powered vehicle which, according to its design and device, is intended for transporting people or goods, for pulling trailers or for harvesting agricultural and / or forestry products. A built three-point link is to be understood in the present case as a three-point link assembled from several separately made items, the several items being rigidly connected to one another. This multi-part design has the advantage over a one-piece three-point link, for example a one-piece cast link or a one-piece forged link, that certain individual parts can be manufactured with variable lengths, which means that different Liche variants of the suspension link can be implemented using a modular principle. In a ferry operation, tensile and / or compressive forces primarily caused by acceleration and braking act on the three-point link installed in a commercial vehicle, in particular on the first and second link arm of the three-point link. In addition, due to the V-shaped arrangement of the link arms, Kraftkom also act on the three-point link in the ferry operation, which causes bending and / or torsional loads in the link arms.

The elastomer joint can be designed, for example, as a molecular joint, which is also referred to as a claw joint. In particular, the elastomer joint has a spherical joint element which is framed by the pretensioned rubber-elastic intermediate layer of the elastomer joint, wherein the spherical joint element does not have to have a real spherical shape, but can also be shaped, for example, in the manner of an ellipsoid, a paraboloid or similar. In particular, the spherical joint element is arranged within the steel bushing. In particular, the spherical joint element and the steel book se, due to the arranged between these, to a certain extent yieldable, rubber-elastic intermediate layer, movable relative to one another under the action of force. The spherical joint element, the rubber-elastic intermediate layer and the steel bushing can form a pre-assembled unit. The rubber-elastic layer can bear directly on an inner wall of the steel bushing or be spaced from it by intermediate components. In particular, the steel bushing can be pot-shaped. In particular, the outer circumference of the steel bushing is round without interruption. In particular, the housing of the central joint for receiving the steel bushing has an uninterrupted, round bore on the inside. In particular, the outer circumferential surface of the steel bushing and the inner circumferential surface of the housing bore are glued to one another. In particular, the first link arm and the second link arm are designed as identical parts. In particular, the first link arm and the second link arm, in order to avoid voltage peaks during ferry operation, are designed to be straight, that is, for example, without end-side cranks or pivoting. In particular, light metal alloys are also intended to be included when a light metal is used in connection with the present invention.

At the level of its axial center, the steel bushing preferably has a circumferential annular collar for absorbing the circumferential stresses resulting from the pretensioning of the rubber-elastic intermediate layer, the annular collar running around the steel bushing on its outer circumference. In particular, the annular collar is designed to be rotationally symmetrical without interruption. In particular, the collar is formed in one piece with the steel bushing.

The first link arm and the second link arm advantageously have straight hollow profile sections made of a fiber composite material with a unidirectional fiber orientation. In particular, the straight hollow profile sections consist of a unidirectional glass fiber reinforced plastic (GRP) or alternatively of a carbon fiber reinforced plastic (CFRP). In particular, the straight hollow profile sections are produced in an inexpensive endless process, for example in a pultrusion process. Continuous fibers of the straight hollow profile sections are preferably incorporated into a polymer matrix. Matrix materials can include epoxy resins, PU Resins or vinyl ester resins. Alternatively, the continuous fibers could also be embedded in a thermoplastic matrix, for example polyamide (PA), polypropylene (PP), polycarbonate (PC), polyphenylene sulfide (PPS) or polyetheretherketone (PEEK). Furthermore, alternatively, the straight hollow profile sections can also be produced in a process using a semi-finished product made from pre-impregnated fibers, a so-called prepreg. In particular, the hollow profile sections have a constant cross-sectional geometry over their longitudinal extent. In particular, the hollow profile sections have a cross-sectional shape that deviates from a circular ring shape. This refinement is particularly advantageous in the case of a transmission of torsion elements in connection areas of the central joint, because a rotational movement within the connection areas can be prevented by a form fit under torsional loading.

The straight hollow profile sections are expediently designed as multi-chamber hollow profile sections. This means that the straight Hohlprofilabschnit te, when viewed in cross section, each have at least two cavities designed as circumferentially closed chambers, which are separated from one another by a web. By means of a multi-chamber hollow profile section, the geometrical moment of inertia of the hollow profile section can be increased as a function of the geometric structure and the arrangement of the multiple chambers relative to one another. This has the effect, in particular in the case of a bending load and / or a torsion load, but also in the case of a pressure load, that higher forces and / or moments can be transmitted.

According to a preferred embodiment, the straight hollow profile sections of the first and second link arms are each rigidly connected to the central joint via an adhesive connection. Compared to hot stamping connections known from the prior art between the ends of steel pipe sections and steel connection pins of central joints, an adhesive connection has the advantage that the risk of component distortion is excluded.

According to a further development, the central joint, for the connection of just the hollow profile sections of the first link arm and the second link arm, Plug-in teeth with teeth extending in the longitudinal direction of the hollow profile sections and dipping into the straight hollow profile sections at the end. In particular, the splines, like the housing of the Zentralge steering, are made of a light metal, especially aluminum. In particular, the splines and the housing are integrally formed. Through the Steckver teeth, the connection area between the joining partners can be enlarged, which is particularly advantageous in an adhesive connection because stresses occurring within the adhesive of the adhesive connection under load can be kept relatively low in this way. The tensions in such an adhesive are generally relatively high under load if the hollow profile consists of a fiber composite material with a plastic matrix and, due to the material, has a significantly lower stiffness than the light metal of the spline. This problem does not arise with the hot stamping connections known from the prior art between steel connecting pins of a central joint and ends of steel pipe sections, because both joining partners are made of the same material, namely steel.

With the spline, the rigidity of the metallic joining partner in the longitudinal direction of the straight hollow profile sections is reduced by geometric measures, namely by the fact that the central joint in the area of the spline is not solid, but reduced by the volume of gaps between the teeth. Advantageously, free ends of the teeth facing the hollow profile section, perpendicular to the longitudinal direction of the hollow profile sections, have a minimal cross-sectional area. This means that teeth of the plug-in teeth, based on their course in the longitudinal direction of the hollow profile sections, have the smallest cross-sectional area at their free ends. As a result, the teeth have an additional reduced rigidity in the longitudinal direction of the hollow profile sections at their free ends. In particular, the adhesive, by means of which the splines are connected to the end sections of the hollow profile sections, has at least partially an increased layer thickness in the area of the free ends of the teeth. As a result of the increased adhesive layer thickness, local stresses in the adhesive layer are reduced and distributed more evenly over the entire adhesive bond. The housing of the central joint and the housing are advantageous in one piece formed splines made from an extruded profile. For this reason, the teeth of the splines can have unmachined outer surfaces resulting from an extrusion process for which further machining is not required.

The teeth of the splines are advantageously glued partly to the outer circumferential surfaces and partly to the inner circumferential surfaces of the straight hollow profile sections. By using both the outer circumferential surfaces and the inner circumferential surfaces of the straight hollow profile sections, an increased connection surface, in particular an increased adhesive surface, is available for the power transmission. Enlarging the adhesive surface increases the load-bearing capacity of the three-point link and at the same time achieves a more homogeneous load introduction into the hollow profile section.

The splines are preferably interspersed with through grooves extending perpendicular to the longitudinal direction of the straight hollow profile sections and at the same time, at least partially, intersecting through grooves. This reduces an imaginary, massive full cross-section in the area of the splines around the material of the through grooves. Since the through grooves penetrate the splines like a grid, the teeth of the splines represent the remaining material. The resulting reduced stiffness of the splines made of a metallic material in the longitudinal direction of the hollow profile sections is advantageous for the aforementioned reasons when gluing the hollow profile sections made of a fiber-reinforced plastic. The through grooves preferably intersect at an angle of essentially 90 degrees. In particular, the through grooves for forming the grid-like structure extend in two directions. In particular, a plurality of through grooves extend in each of the two directions perpendicular to the longitudinal direction of the straight hollow profile sections parallel to one another.

Advantageously, the housing of the central joint is divided into two housing halves and the steel bushing is fixed in its position in that an annular collar of the steel bushing extends into a transverse division plane between the two housing halves. In particular, the collar is framed in a form-fitting manner between the two housing halves. In particular, the collar extends evenly if in the division level. In particular, the two housing halves are glued and / or pinned to one another in the transverse division plane. In particular, the transverse division plane extends perpendicular to an axial longitudinal direction of the steel bush, which is intended to be expressed by the term “transverse division plane”.

According to a first alternative, the transverse dividing plane extends in a plane that is spanned by the first link arm and the second link arm. Alternatively, the transverse division plane can also extend perpendicular to a plane spanned by the first link arm and the second link arm. In particular, the transverse division plane also runs through the splines of the Zentralge steering, the straight hollow profile sections are designed as multi-chamber hollow profile sections and each have at least one web that is framed by teeth of the two housing halves.

Preferably, a joint axis of the central joint extends at least substantially perpendicular to a plane that is spanned by the first link arm and the two-th link arm. Alternatively, the hinge axis can also extend at least essentially in a plane that is spanned by the first link arm and the second link arm.

Advantageously, the first link arm and the second link arm have straight hollow profile sections that are mitred at least at one end facing the central joint in order to achieve a homogeneous load transfer when the respective link arm is subjected to a pressure load by means of a flat frontal contact with the central joint.

Appropriately, the first link arm and the second link arm straight Hohlpro filabschnitte which are each connected at their ends facing away from the central joint via an adhesive connection with a load introduction element made of a light metal, in particular aluminum. In particular, the load introduction elements each have a spline facing the associated hollow profile section, as described above. In the following, the invention is explained in more detail using only one exemplary embodiment of the drawings, wherein the same reference numerals refer to the same, similar or functionally identical components or elements. It shows:

1 shows a schematic plan view of a utility vehicle according to the prior art;

Fig. 2 is a perspective view of a three-point link according to the inven tion;

FIG. 3 shows a sectional illustration of the three-point link from FIG. 2 according to the section AA indicated there;

4 shows the three-point link from FIG. 4 in a perspective exploded view

2;

FIG. 5 shows a sectional illustration of a multi-chamber hollow profile section from FIG. 4 according to the section line BB indicated there;

FIG. 6 shows a sectional illustration of the three-point link from FIG. 2 according to the section line C - C and indicated there

FIG. 7 shows the three-point link from FIG. 2 in a sectional illustration according to the section line D - D indicated in Fi gur 6.

1 shows a utility vehicle 1 with a vehicle frame 2 which has two lateral longitudinal members 3 which are connected to one another by three cross members 4. A rear axle is connected to the vehicle frame 2, which is designed as a rigid axle 5 and is guided, among other things, by a three-point link 6 connected to the vehicle frame 2. The three-point link 6 has a first Len kerarm 7 and a second link arm 8, wherein the two link arms 7, 8 are arranged in a V-shape at an acute angle to each other and in one

Meet the central joint 9. 2 shows an assembled three-point link 6 for guiding a rigid axle 5 of a utility vehicle 1, the three-point link 6 having a first link arm 7 and a second link arm 8. The two link arms 7, 8 are arranged in a V-shape at an acute angle to each other and meet in a central joint 9. The first link arm 7 and the second link arm 8 each have a straight hollow profile section 10, 11 made of a fiber composite material with a unidirectional fiber alignment on. The straight hollow profile sections 10, 11 of the first 7 and second link arm 8 are each rigidly connected to the central joint 9 via an adhesive connection 12. In addition, the straight hollow profile sections 10, 11 at their free ends facing away from the central joint 9 are each rigidly connected to a load introduction element 14, 15 made of an aluminum alloy via an adhesive connection 13. To connect the straight hollow profile sections 10, 11, the Lastein line elements 14, 15 have splines with teeth 27 extending in the longitudinal direction of the straight hollow profile sections 10, 11, which dip at the front into the straight hollow profile sections 10, 11 and there with the hollow profile sections 10 , 1 1 are glued. The two load introduction elements 14, 15 each have a Mole joint 16, 17. The central joint 9 has a housing 18 which is divided into two housing halves 19, 20.

In Fig. 3 it can be seen that the central joint is formed out as an elastomer joint 9 and the housing 18 has a pretensioned rubber-elastic intermediate layer 21 arranged therein. The housing 18 consists of an aluminum alloy and the pretensioned, rubber-elastic intermediate layer 21 is surrounded by a steel bush 22 which is cup-shaped. The steel bushing 22 absorbs circumferential stresses which originate from a pretensioning of the rubber-elastic intermediate layer 21, so that the housing 18 of the central joint 9 only has to absorb pure chassis forces during ferry operation. An annular collar 23 of the steel bushing 22 extends into a transverse division plane 24 between the two housing halves 19, 20, whereby the steel bushing 22 is fixed in its axial position. The transverse dividing plane 24 extends in a plane which is spanned by the first link arm 7 and the second link arm 8. The two housing halves 19, 20 are pinned and glued together in the transverse partition plane 24. The Elastomer joint 9 has a spherical joint element which is enclosed by the prestressed rubber-elastic intermediate layer 21, the spherical joint element being arranged within the steel bushing 22. The spherical Ge articulating element, which is screwed to a dome of a flange plate, the rubber-elastic liner 21 and the steel bushing 22 form a pre-assembled unit.

From Fig. 4 it is clear that the collar 23 runs around the steel bushing 22 at the level of its axial center and at the same time on its outer circumference. To connect the straight hollow profile sections 10, 11 to the central joint 9, the two housing halves 19, 20 made of an aluminum alloy each have a spline 25 with teeth 27 extending in the longitudinal direction of the hollow profile sections 10, 11. The splines 25 are constructed similarly to the splines of the two load application elements 14, 15 made of an aluminum alloy. The straight hollow profile sections 10, 11 are designed as multi-chamber hollow profile sections, each with two circumferentially closed chambers, which are separated from one another by a web 28. A joint axis 26 of the central joint 9 extends essentially perpendicular to a plane that is spanned by the first link arm 7 and the second link arm 8.

Fig. 5 shows the straight multi-chamber hollow profile section 1 1 with the two circumferentially Lich closed chambers that are separated from one another by the web 28. The multi-chamber hollow profile section 11 has, when viewed in the present cross section, from its outer circumferential surfaces and from its inner circumferential surfaces projecting, narrow thickenings. Due to these thickenings, the joint surfaces of the two joint partners are kept at a minimum distance in the Be rich of the adhesive joints 12, 13. The thickened areas extend in a strip-like manner over the entire length of the multi-chamber hollow profile section 11. In the present case, the thickenings project by about 0.3 millimeters from the aforementioned outer or inner circumferential surfaces and have a width of about 3 millimeters.

When inserting the spline 25 into the straight multi-chamber hollow profile section 11, the thickenings represent guide surfaces. In the area of the thickenings, the layer thickness of the adhesive is mathematically 0.2 millimeters, which makes it clear that the spline 25 and the straight multi-chamber Hollow profile section 11 alternately interlock with only a small amount of play, ie essentially form-fitting. The multi-chamber hollow profile section 11 has in the present section, to increase the bending stiffness, the torsional stiffness and the buckling stiffness of the second link arm 8 six outwardly protruding ribs.

In Fig. 6 it can be seen that the teeth 27 of the spline 25 are partly glued to outer peripheral surfaces and partly to the inner peripheral surfaces of the straight multi-chamber hollow profile section 11. The teeth 27 of the spline 25 have a rectangular full cross-section and are formed in one piece with the two housing halves 19, 20, which are separated from one another by the transverse plane 24. The four canines happen to have a square full cross-section as a special form of a rectangular full cross-section in the selected cutting plane. Between each two ribs of the multi-chamber hollow profile section 11, recesses that are open towards the outside of the profile are formed, into each of which a tooth 27 of the plug-in toothing 25 engages.

7 shows a longitudinal section through a connection area in which the second link arm 8 is rigidly connected to the central joint 9 via the splines 25 of both housing halves 19, 20. The straight multi-chamber hollow profile section 11 of the second link arm 8 is mitred at its end facing the central joint 9 in order to achieve a homogeneous load transfer transition through a flat face contact with the central joint 9 when the second link arm 9 is subjected to pressure. At the abutment surface of the multi-chamber hollow profile section 11, the latter can rest directly on the central joint housing 18, with a tolerance compensation with adhesive preferably being provided. The transverse division plane 24 between the splines 25 of the two housing halves 19, 20 runs in such a way that the web 28 of the straight multi-chamber hollow profile section 11 is enclosed by teeth 27 of the two housing halves 19, 20. Reference symbol

Commercial vehicle

Vehicle frame

Side member

Cross member

Rigid axle

Three-point link

first link arm

second link arm

Central joint, elastomer joint

straight hollow profile section, straight multi-chamber hollow profile section, straight hollow profile section, straight multi-chamber hollow profile section

Adhesive connection

Load introduction element

Molecular joint

casing

Housing half

rubber-elastic intermediate layer

Steel bushing

Ring collar

Dividing level

Splines

Joint axis

Tooth of the spline

web

Claims

1. Three-point link (6) as a built three-point link for guiding a rigid axle (5) of a commercial vehicle (1), the three-point link (6) having a first link arm (7) and a second link arm (8), the two link arms (7, 8 ) Are arranged in a V-shape at an acute angle to each other and meet in a central joint (9), the central joint (9) being designed as an elastomer joint and having a housing (18) with a prestressed rubber-elastic intermediate layer (21) arranged therein , characterized in that the housing (18) consists of a light metal and the pretensioned rubber-elastic intermediate layer (21) is surrounded by a steel bushing (22) which absorbs peripheral stresses which result from the pretensioning of the rubber-elastic intermediate layer (21), so that the Housing (18) of the central joint (9) only has to absorb pure chassis forces in a ferry operation.

2. Three-point link (6) according to claim 1, characterized in that the steel bushing (22) at the level of its axial center has a circumferential annular collar (23) for receiving the circumferential stresses resulting from the biasing of the rubber-elastic intermediate layer (21), has, wherein the collar (23) the steel sleeve (22) runs around its outer circumference.

3. Three-point link (6) according to claim 1 or 2, characterized in that the first link arm (7) and the second link arm (8) straight hollow profile sections (10, 11) made of a fiber composite material with unidirectional fiber orientation aufwei sen.

4. Three-point link (6) according to claim 3, characterized in that the straight hollow profile sections (10, 11) are designed as multi-chamber hollow profile sections.

5. Three-point link (6) according to claim 3 or 4, characterized in that the straight hollow profile sections (10, 1 1) of the first (7) and the second link arm (8) are each rigidly connected to the central joint (9) via an adhesive connection (12) ) are connected.

6. Three-point link (6) according to one of the preceding claims, characterized in that the central joint (9), for connecting straight Hohlprofilabschnit th (10, 1 1) of the first link arm (7) and the second link arm (8), Steckver serrations (25) with teeth (27) which extend in the longitudinal direction of the hollow profile sections (10, 1 1) and which dip into the straight hollow profile sections (10, 1 1) at the end.

7. Three-point link (6) according to claim 6, characterized in that the teeth (27) of the splines (25) are glued partly with outer peripheral surfaces and partly with inner peripheral surfaces of the straight hollow profile sections (10, 1 1).

8. Three-point link (6) according to claim 6 or 7, characterized in that the splines (25) of perpendicular to the longitudinal direction of the straight hollow profile sections (10, 1 1) extending and at the same time, at least partially, intersecting grooves are traversed like a grid .

9. Three-point link (6) according to one of the preceding claims, characterized in that the housing (18) of the central joint (9) is divided into two housing halves (19, 20) and the steel bushing (22) is thereby fixed in its position, that an annular collar (23) of the steel bushing (22) extends in a transverse division plane (24) between tween the two housing halves (19, 20).

10. Three-point link (6) according to claim 9, characterized in that the transverse division plane (24) extends in a plane which is spanned by the first link arm (7) and the second link arm (8).

1 1. Three-point link (6) according to one of the preceding claims, characterized in that a hinge axis of the central joint (9) extends at least essentially perpendicular to a plane spanned by the first link arm (7) and the second link arm (8) .

12. Three-point link (6) according to one of the preceding claims, characterized in that the first link arm (7) and the second link arm (8) are straight Hollow profile sections (10, 11) which are mitred at least at one end facing the central joint (9) in order to be able to use a flat frontal contact with the central joint (9) when the respective steering arm (7, 8) is subjected to pressure. to achieve a homogeneous load transfer.

13. Three-point link (6) according to one of the preceding claims, characterized in that the first link arm (7) and the second link arm (8) have straight hollow profile sections (10, 1 1), which turned abge at their the central joint (9) Ends each via an adhesive connection (13) with a load introduction element (14, 15) made of a light metal, in particular aluminum, are connected.