DE102019212696A1 - Axle suspension for a vehicle - Google Patents

Abstract

The invention relates to an axle suspension (1) for a vehicle, with a leaf spring unit (2) which extends in the longitudinal direction (X) of the vehicle and is supported on a vehicle axle (10) and which at its ends (2.1, 2.2) is at least indirectly connected to a vehicle body (20 ) connected is. In order to provide an axle suspension with an optimized structure, the invention provides that a connecting arrangement (3) arranged at a first end (2.2) of the leaf spring unit (2), with a spring-side guide element (4) attached to the first end (2.1) and a body-side guide element (5) connected to the vehicle body, against which the spring-side guide element (4) is guided along a guide path (F) extending in the vehicle longitudinal direction (X) and can be pivoted about a first pivot axis (A).

Description

The invention relates to an axle suspension for a vehicle, with the features of the preamble of claim 1.

Various types of springs are used in the wheel suspension of modern motor vehicles, via which the actual vehicle body is connected to the wheels of the vehicle. In addition to coil springs, leaf springs are also used, especially for rigid axles. Such a leaf spring extends along the longitudinal axis of the vehicle and generally has a concave shape under normal load. In addition to leaf springs made of spring steel, leaf springs made of composite material, for example fiber-reinforced plastic, are sometimes used. Individual springs or spring assemblies made up of two or more springs can be used. The at least one spring is normally connected to the axle to be sprung in a central area via a tensioning device, for example by spring clips. A typical structure is the so-called Hotchkiss suspension, in which the leaf spring is connected to the vehicle structure at a front end via a first pivot axis, while a connecting arm is connected to the rear end of the leaf spring via a second pivot axis and to the rear end of the leaf spring via a third pivot axis Vehicle body is connected. The connecting arm, which is also referred to as a shackle, can be designed in one or more parts and normally extends from the vehicle body down to the leaf spring. Its function is primarily to provide the necessary length compensation between the front and rear ends of the leaf spring during compression and the resulting change in the curvature of the leaf spring. The connecting arm, which under normal load extends from the vehicle body down to the rear end of the leaf spring, takes up a relatively large amount of space or ensures that the rear end of the leaf spring is arranged relatively low in relation to the vehicle body, which is unfavorable in terms of ground clearance.

It is often desirable to have two different spring constants for a sprung axle. Up to a certain limit load, the axle should be sprung with a lower spring constant or stiffness. This corresponds to smaller spring movements that occur during normal driving. It is generally advantageous here if the suspension does not react too hard. A higher spring constant should be given above a limit load. This also corresponds to a greater spring deflection, which is generally not achieved, for example, during normal driving, but only in individual situations such as, for example, driving through a pothole or the like. In this case it is advantageous if the suspension reacts harder in order, for example, to prevent a bottoming out, that is to say parts hitting one another. In the event of such a bottoming out, for example, the sprung axle could collide with part of the vehicle body, which in the worst case could damage parts of the vehicle. Above all, however, a harder suspension can be advantageous when there is a higher static load on the corresponding axle (e.g. on a loaded truck), as this improves steering and driving behavior overall. Spring systems, which, depending on the load, react with two different spring constants or spring rates, are also referred to as two-stage springs or two-stage suspensions. More generally, one can also speak of a progressive suspension, although it is not necessary to clearly distinguish between two different spring rates; rather, the spring rate can also change continuously.

One possibility known in the prior art for realizing two different spring constants consists in arranging two (or more) leaf springs in the form of a spring assembly, with a primary spring serving as a connection to the vehicle body and thus constantly contributing to the suspension. A secondary spring is connected to the primary spring, but, due to its shape, only experiences a deformation if the primary spring itself is deformed to a greater extent. This means that the secondary spring only generates a restoring force in the event of greater deformation, i.e. with a larger (static or dynamic) axle load. The secondary spring is usually tensioned against the primary spring in a central area, with high tension forces being necessary to prevent the two springs from being displaced relative to one another. In the case of leaf springs made of composite material, however, such tension forces can lead to creeping or damage to the leaf spring. In addition, the additional spring requires installation space, increases the mass of the suspension and, if it is arranged below the primary spring, leads to a lower ground clearance.

A further possibility for realizing a two-stage suspension is provided by leaf-tension springs manufactured in a composite construction. Such systems are, for example, from the EP 3 017 211 B1 and the EP 2 885 554 B1 known. It is characteristic that a spring has a concavely curved leaf spring section and an oppositely curved and downwardly extending end section via which it is attached to the vehicle body. Both sections can be made in one piece from composite material or the end section can consist of spring steel. The spring has an overall S-shaped curvature, which enables length compensation. It is about the stretching The S-shaped curvature for length compensation induces a tensile force acting in the longitudinal direction in the spring, which causes an increase in the vertical spring rate. The length compensation is thus accompanied by a change in the spring rate. The manufacture of such tension springs is complex since, in addition to the variable vertical spring rate, a sufficiently high lateral stability and durability of the spring must be guaranteed. In addition, the generally low attachment point of the end section is disadvantageous in terms of ground clearance.

The DE 10 2014 005 948 A1 shows a leaf spring with a first and a second end, wherein the leaf spring has in the longitudinal direction a concave central region beginning at the first end and extending in the direction of the second end, which is adjoined in the longitudinal direction in the region of the second end by a wave-shaped region which has at least one convex sub-area and at least one concave sub-area, the convex sub-area following the central area.

The DE 10 2016 216 149 A1 discloses a suspension system with a leaf spring unit made of composite material, which extends along a vehicle longitudinal axis, is connected at a front end to a vehicle body and has a connection area for a vehicle axle. A connecting arm is pivotably connected on the one hand to a rear end of the leaf spring unit and on the other hand to the vehicle body, the leaf spring unit at the front end being rigidly connected to the vehicle body and having a longitudinally elastic section with at least two alternating upward and downward sections between the front end and the connection area.

From the JP 2003-335119 A an axle suspension is known, with a leaf spring having a thicker front leaf which is fastened at a rear end to an axle and extends substantially straight forward to a bearing eye which is pivotably connected to the vehicle body. Furthermore, the leaf spring has a thinner rear leaf which has a portion bent towards the vertical and which is connected to an extended part of the rear end of the front leaf. The rear blade is connected to the vehicle body at a rear end by a further bearing eye.

The DE 10 2010 015 951 A1 discloses a leaf spring for motor vehicles made of a fiber-reinforced plastic material, the leaf spring being able to absorb any lateral guiding forces that may occur and transfer them to a leaf spring receiving device. A first end and a second end of the leaf spring can be fixed in the leaf spring receiving device so as to be torque-proof and non-displacement-proof, and the leaf spring has a flexure joint section that can compensate for a change in length of the spring section of the leaf spring in the event of a load-related deformation of the spring section.

In view of the prior art shown, the provision of a rear axle suspension with an optimized structure, in particular when providing a progressive suspension, definitely still offers room for improvement.

The invention is based on the object of providing an axle suspension with an optimized structure.

According to the invention, the object is achieved by an axle suspension having the features of claim 1, the subclaims relating to advantageous embodiments of the invention.

It should be pointed out that the features and measures listed individually in the following description can be combined with one another in any technically meaningful manner and show further embodiments of the invention. The description additionally characterizes and specifies the invention, particularly in connection with the figures.

The invention provides an axle suspension for a vehicle. The vehicle can in particular be a motor vehicle such as a truck or car. However, it can also be used for trailers, for example. The axle suspension is generally a rear axle suspension, in particular a rigid axle suspension.

The axle suspension has a leaf spring unit which extends in the longitudinal direction of the vehicle and is supported on a vehicle axle and which is at least indirectly connected at its ends to a vehicle body. The leaf spring unit is connected directly or indirectly to the vehicle axle and is supported on it. One could also say that the leaf spring unit supports the vehicle body against the vehicle axle or vice versa. The vehicle axle can be arranged above or below the leaf spring unit. In this context, the leaf spring unit is a unit extending along the longitudinal axis of the vehicle (X-axis) with at least one leaf spring, one could also say a longitudinal leaf spring unit. In general, at least in the unloaded state, it does not run parallel to the X axis, but rather has a concave curvature, for example. All references to the X-axis (longitudinal axis), Y-axis (transverse axis) and the Z-axis (vertical axis) of the Vehicle refer here and in the following to the properly installed state of the axle suspension. It goes without saying that the axle suspension is normally constructed symmetrically and thus a leaf spring unit is arranged on each of the opposite sides of the vehicle.

The leaf spring unit can usually be made from spring steel or from composite material, in particular fiber composite material. If the leaf spring unit has more than one leaf spring, these leaf springs can also consist of different materials.

Overall, the leaf spring unit is used for the elastic suspension of the vehicle axle relative to the vehicle body. "Vehicle structure" is a collective term for a body, a chassis and, if applicable, a subframe of the respective vehicle, i.e. those parts that normally form the sprung mass. The connection between the vehicle axle, which can in particular be designed as a rigid axle, and the leaf spring unit is normally provided via a clamping device, which, for example, can have an upper and a lower clamping element, which can be relatively rigid in themselves, e.g. made of steel. The leaf spring unit is clamped between the tensioning elements, possibly via intermediate elastic insulating elements. The tensioning elements can be braced against each other using spring clips.

The leaf spring unit is at its ends, one could also say at the end, at least indirectly connected to the vehicle body. In particular, the respective front and rear ends of the leaf spring unit can be pivotably connected to the vehicle body. Such pivotability is used in a known manner to prevent excessive local stresses within the leaf spring unit when it is compressed.

According to the invention, a connection arrangement is arranged at a first end of the leaf spring unit, with a spring-side guide element attached to the first end and a body-side guide element connected to the vehicle body, on which the spring-side guide element can be moved along a guide path extending in the longitudinal direction of the vehicle and is pivotable about a first pivot axis . The first end is usually the back end, but it can also be the front end if necessary. The connection arrangement serves to connect the leaf spring unit at the first end to the vehicle body. It has two mutually displaceable guide elements.

A spring-side guide element is attached to the first end of the leaf spring unit. It can optionally also be manufactured in one piece with the leaf spring unit, for example the spring-side guide element and the leaf spring unit (or a leaf spring of the same) could form sections of an element made of fiber composite material. With regard to manufacture and assembly, however, it is generally preferred that the leaf spring unit and the spring-side guide element are manufactured separately. This means that these are first prefabricated separately from one another and then connected to one another. The connection can be designed in a form-fitting, force-fitting and / or cohesive manner. The spring-side guide element can be elastic to a limited extent, but it is preferably rigid, i.e. it experiences at most a negligible deformation during normal driving of the vehicle. The spring-side guide element can be made from the same material or from a different material. For example, it could be cast from steel, cast iron or aluminum, or it could be formed from fiber composite. Fiber composites include all materials in which fibers, such as glass fibers, carbon fibers and / or aramid fibers, are embedded in a polymer matrix (e.g. a plastic or synthetic resin matrix) for reinforcement. Optionally, further particles, layers or components can be incorporated or deposited that cannot be classified as polymers or fibers. The spring-side guide element can be manufactured in one or more parts.

A body-side guide element is connected to the vehicle body and the spring-side guide element is guided on the body-side guide element along a guide path extending in the longitudinal direction of the vehicle and can be pivoted about a first pivot axis. Two kinds of movements of the spring-side guide element relative to the body-side guide element are thus possible. On the one hand, a translational movement is possible, with the spring-side guide element being guided and displaceable on the body-side guide element. The translational movement is guided, that is, no arbitrary translational movements are possible, but rather along a guide path that extends in the longitudinal direction of the vehicle. In general, this does not mean that the guide path runs parallel to the vehicle longitudinal axis (X-axis), but only that it extends in the vehicle longitudinal direction. The guide path naturally corresponds to the course of a type of guide profile, guide slot, guide groove, guide rail or the like, via which the two guide elements engage with one another. A positive fit is provided perpendicular to the guide path, which at least largely enables a relative movement of the two guide elements limited. However, a slight relative movement perpendicular to the guide path is possible and generally cannot be avoided. The geometrical course of the guide path can be chosen differently, for example it can be straight, concavely curved, convexly curved or also curved in an S-shape. The body-side guide element can be made in one piece, but in particular also in multiple pieces. Like the spring-side guide element, it can be made of different materials, for example metal or fiber composite.

Furthermore, the spring-side guide element on the body-side guide element - one could also say, with respect to the body-side guide element - can be pivoted about the named first pivot axis. The first pivot axis is normally arranged stationary with respect to the vehicle body, so that it can also be said that the spring-side guide element can pivot about the first pivot axis with respect to the vehicle body.

In contrast to a Hotchkiss suspension, where a connecting arm is used to provide length compensation between the first pivot axis and the second pivot axis when the leaf spring unit is compressed and rebounded, the axis suspension according to the invention provides length compensation by the guided displacement of the spring-side guide element reached the body-side guide element. This means that the connecting arm and its pivoting movement in relation to the vehicle body are not required. According to the invention, the pivoting movement is replaced by the translational displacement of the spring-side guide element with respect to the body-side guide element.

At the same time, the pivotability of the spring-side guide element with respect to the body-side guide element prevents the guide elements from tilting if the angle of the first end of the leaf spring (and thus of the spring-side guide element) changes in relation to the body-side guide element during compression.

The solution according to the invention has advantages in particular with regard to the required installation space and the clearance from the ground. In order to perform its function, a link arm known in the prior art must necessarily extend a certain distance along the vertical, usually downwards. Thus, either the leaf spring connected to it is arranged comparatively low compared to the vehicle body, which has a disadvantageous effect on the ground clearance, or the body-side connection point of the connecting arm is arranged comparatively high, which takes up a relatively large amount of space on the vehicle body. Similar disadvantages arise in the variant also known in the prior art, in which the connecting arm extends upwards. These disadvantages, which ultimately result from the kinematic limitations of the pivoting movement of the connecting arm, do not apply to the solution according to the invention. Instead, there is a translational shift along the guide path, the body-side guide element not having to perform any or only a comparatively slight pivoting movement. As will become even clearer below, the entire connection arrangement can be implemented in a very space-saving manner. In particular, the space requirement in the vertical direction is reduced compared to a Hotchkiss suspension. It is also conceivable to design the geometry of the guide path in different ways in order to adjust the kinematics of the axle suspension in different ways as required. It is also in contrast to the Hotchkiss suspension, where the pivoting movement of the connecting arm always defines an arc-shaped movement line of the end of the leaf spring.

Apart from the advantages mentioned, the number of components required can be reduced compared to a Hotchkiss suspension. This generally has a positive effect on the total mass of the vehicle and in particular on the unsprung mass. It goes without saying that this also optimizes the time and costs involved in assembling the axle suspension. In this regard, the leaf spring unit can be designed essentially identically as in a classic Hotchkiss suspension. One difference is that the spring-side guide element is attached to the first end of the leaf spring unit, which, for example, replaces a bearing eye that is used for a pivotable connection to the connecting arm in a Hotchkiss suspension.

In principle, it would be conceivable that the leaf spring unit has two or more leaf springs and is thus designed as a leaf spring package. In terms of a compact design with few components, in which the function of the secondary spring is performed solely by the connecting arm, it is preferred, however, that the leaf spring unit is designed as a single leaf spring. As already mentioned above, such a single (longitudinal) leaf spring can be made either from spring steel or from composite material.

In a particularly advantageous embodiment, the connecting arrangement has at least one restoring element which is arranged between the spring-side guide element and the body-side guide element and which is produced by shifting the guide elements relative to one another is elastically deformable along at least part of the guide path. The term “restoring element” means that it is designed to generate a restoring force between the guide elements. The restoring force is based on the deformation of the restoring element, which is of course designed to be elastically deformable for this purpose. At least along part of the guide path, a displacement of the guide elements leads to an elastic deformation, for example compression or extension, of the restoring element. The restoring element is interposed between the two guide elements, which can relate to both the spatial arrangement and the course of a force flow.

The two guide elements can interact with one another via the return element. A further element could optionally be arranged between at least one guide element and the restoring element. Since the displacement of the guide elements corresponds to a compression or rebound of the vehicle axle, the deformation of the restoring element results in an additional restoring force compared to that resulting from the deformation of the leaf spring unit. Depending on the design of the guide path and of the at least one restoring element, the increase in the additional restoring force can be influenced in different ways. In particular, it is possible in this way to implement a progressive suspension. This can result solely from the fact that in the event of a slight deflection of the vehicle axle, a necessary length compensation between the ends of the leaf spring unit is slight and thus at most leads to a slight deformation of the restoring element. With stronger compression, the necessary length compensation and thus the deformation of the restoring element increases. The effective spring rate increases accordingly.

With regard to the design of the restoring element, there are different options. At least one return element can be designed as a spring. In particular, it can be a helical spring which can be formed from spring steel or fiber-reinforced plastic. Alternatively or additionally, at least one restoring element can be designed as an elastomeric element. This element, which can also be referred to as a rubber-elastic element, can, for example, be made of rubber, caoutchouc, silicone or another suitable material. It would be conceivable that the elastomeric element is materially connected to at least one of the guide elements, for example by vulcanization.

At least one restoring element can advantageously be compressed by compressing the vehicle axle. That is, when the vehicle axle compresses, the corresponding resetting element is compressed or compressed. Alternatively, it would basically also be conceivable that the restoring element is pulled apart during compression. However, this variant is generally more difficult to implement, since suitable connections must be made to transmit the tension to both guide elements. In the case of an elastomeric element in particular, the compression can also lead to the effective spring rate increasing particularly quickly when the compressibility of the corresponding restoring element approaches a maximum limit given by the geometry and material properties.

A guide element can advantageously have at least one elongated guide recess which defines the guide path, in which the other guide element engages and to which it is relatively displaceable. The guide recess can, for example, be designed as a slot or groove. Its course corresponds to the guide route and defines it. This guide recess is formed on the one (that is to say body-side or spring-side) guide element, while the other (that is, spring-side or body-side) guide element engages in it. By engaging, the above-described guidance of the two guide elements relative to one another is of course implemented. The other guide element is displaceable relative to the guide recess, which expressly includes the possibility that the other guide element remains stationary with respect to the vehicle structure and instead the guide recess is displaced with respect to the vehicle structure, as well as the possibility that the guide recess remains stationary and the other guide element is displaced .

The spring-side guide element preferably has the at least one guide recess into which the body-side guide element engages, whereby it can be displaced guided along the body-side guide element. The body-side guide element is usually stationary relative to the vehicle body or at most rotatable relative to it, while the spring-side guide element with the guide recess moves relative to the body-side guide element and the vehicle body when the vehicle axle springs in or out.

According to an advantageous embodiment, the spring-side guide element has a housing in which at least one restoring element is received and which has two guide recesses spaced along the first pivot axis through which the body-side guide element is passed. The spring-side guide element is used for receiving and Storage of the at least one restoring element, the corresponding housing having an at least partially closed shape which can also protect internal components from damage or contamination. The body-side guide element is passed through two guide recesses spaced apart along the first pivot axis or it extends through them. The mentioned guide recesses are formed in opposite sections of the wall of the housing. They can also be referred to as guide slots. The body-side guide element thus extends through the spring-side guide element.

In an advantageous embodiment, the body-side guide element has an axle element fastened to the vehicle body and a sleeve element rotatably mounted on the axle element about the first pivot axis, which cooperates with the spring-side guide element for guidance. The axle element can be formed, for example, by an axle bolt that is attached to the vehicle body. For example, it could be a screw that is secured with an appropriate nut. The sleeve element is rotatably mounted on the axle element about the first pivot axis. The rotatable mounting can be implemented, for example, via a plain bearing, but possibly also via a roller bearing. An elastic bearing bushing can optionally be provided between the two mentioned elements, for example to minimize the transmission of vibrations from the vehicle axle to the vehicle body. It is also conceivable to connect the axle element to the vehicle body via an elastic element (bearing bush or similar) in order to suppress the transmission of vibrations. The term “sleeve element” is not to be interpreted restrictively in this context, although the sleeve element typically surrounds the axle element in the manner of a sleeve. The sleeve element in turn interacts with the spring-side guide element for guidance, i.e. the guided displaceability of the spring-side guide element relative to the body-side guide element is ensured by the interaction of the sleeve element and the spring-side guide element. The sleeve element can - possibly also depending on the respective design - be viewed as part of the body-side guide element or as an "additional" element that is interposed between the spring-side guide element and the body-side guide element. In this embodiment, the displaceability on the one hand and the pivotability on the other hand are divided between the interaction of two different component pairs. The pivotability is at least predominantly realized by the interaction of the axle element and the sleeve element, while the displaceability is realized by the interaction of the sleeve element and the spring-side guide element. However, this does not exclude the possibility that the sleeve element could be designed to be rotationally symmetrical, so that it would in principle also be rotatable against the spring-side guide element. In this way, the sleeve element could roll off the spring-side guide element, which would, for example, reduce friction and wear. The embodiment described here can in particular be combined with one of the embodiments described above, so that the sleeve element can be displaced in at least one guide recess or the sleeve element and the axle element can be guided through the guide recesses.

On the one hand, it is possible that any small displacements of the two guide elements lead to a deformation of the at least one restoring element. This also enables progressive suspension to be implemented. In some cases, however, it is desirable that the spring rate is determined exclusively by the leaf spring unit up to a certain axle load and that the effect of the at least one restoring element also comes into play above this axle load. In one embodiment of the invention, therefore, at least one restoring element is dimensioned such that it is spaced apart and decoupled from at least one guide element when the guide elements are displaced relative to one another along at least part of the guide path. If the two guide elements move along said part of the guide path, there is no deformation of the restoring element and the spring rate is determined exclusively by the leaf spring unit. If the guide elements are shifted further in relation to one another, the restoring element is also deformed, which has an effect on the spring rate. This results in a two-stage suspension. For example, the corresponding restoring element could be attached to the spring-side guide element and dimensioned so that there is a distance between the body-side guide element and the restoring element in the event of a slight compression. If the guide elements move against each other with increasing compression, the body-side guide element moves towards the restoring element and finally comes into contact with it, so that a further displacement leads to an elastic deformation of the restoring element. Of course, the reset element could also be attached to the guide element on the body side. It is also conceivable that there is no fastening at all, but that the restoring element is received, for example, in the above-mentioned housing and, in the case of slight compression, is arranged loosely between the two guide elements and only above a certain one Axle load is deformed between the guide elements, in particular compressed.

According to one embodiment, the leaf spring unit is connected to the vehicle body at the second end by a pivot bearing so that it can pivot about a second pivot axis. The second end of the leaf spring unit can have a bearing eye which is pivotably mounted on an axle bolt on the body side, for example via a rubber-metal bushing. Since the position of the pivot bearing on the leaf spring does not change, the length compensation takes place exclusively via the first end. For the kinematics of the vehicle axle, this means that it always moves not only vertically, but also horizontally during compression. If this effect is acceptable, this embodiment has the advantage that the named pivot bearing can be implemented simply and cost-effectively.

Under certain circumstances, however, an essentially purely vertical movement of the vehicle axle during compression may also be desirable. This cannot be achieved at all with a Hotchkiss suspension, for example. In contrast, this is possible with the axle suspension according to the invention. According to one embodiment, a connecting arrangement is arranged at each end of the leaf spring unit. That is, a connection arrangement is also arranged at the second end, the basic structure of which corresponds to the connection arrangement described above at the first end. That is, this also has a spring-side guide element, a body-side guide element and optionally at least one return element. The two connection arrangements can be designed in the same way or differently. It would be possible, for example, to implement a completely symmetrical connection of the leaf spring unit to the vehicle body. On the other hand, an asymmetrical structure could also be selected, for example so that the vehicle axle does not move vertically as planned during compression.

• 1 eine Seitenansicht einer ersten erfindungsgemäßen Achsaufhängung bei normaler Achslast;
• 2 eine Seitenansicht der Achsaufhängung aus 1 bei erhöhter Achslast;
• 3 eine Detailansicht der Achsaufhängung entsprechend 1;
• 4 eine Schnittdarstellung gemäß der Linie IV-IV in 3;
• 5 eine Detailansicht der Achsaufhängung entsprechend 2;
• 6 eine Detailansicht einer zweiten erfindungsgemäßen Achsaufhängung; sowie
• 7 eine Seitenansicht einer dritten erfindungsgemäßen Achsaufhängung.

Further advantageous details and effects of the invention are explained in more detail below with reference to the exemplary embodiments shown in the figures. Show it

• 1 a side view of a first axle suspension according to the invention with normal axle load;
• 2 a side view of the axle suspension 1 with increased axle load;
• 3 a detailed view of the axle suspension accordingly 1 ;
• 4th a sectional view along the line IV-IV in 3 ;
• 5 a detailed view of the axle suspension accordingly 2 ;
• 6th a detailed view of a second axle suspension according to the invention; such as
• 7th a side view of a third axle suspension according to the invention.

In the different figures, the same parts are always provided with the same reference numerals, which is why they are usually only described once.

1 shows a first embodiment of an axle suspension in a highly schematic manner 1 that can be used, for example, in a truck or, for example, in a transporter. There is a rear axle designed as a rigid axle 10 by a longitudinal leaf spring 2 made of spring steel or fiber composite with a vehicle body 20th connected. While the rear axle 10 extends parallel to the Y-axis, extends the longitudinal leaf spring 2 along the X axis. 1 shows a normal axle load state in which the longitudinal leaf spring 2 is slightly concave, but depending on the load, it can also have a convex curvature (see 2 ) or also have a straight stretch within the XZ plane. The longitudinal leaf spring 2 can be connected to the rear axle via a clamping device that is only hinted at 10 be connected.

A back end 2.2 the longitudinal leaf spring 2 has a spring-side guide element 4th on which part of a connection arrangement 3 is over which the longitudinal leaf spring 2 with the vehicle body 20th connected is. The spring-side guide element 4th can for example be made of metal and has the rear end 2.2 the longitudinal leaf spring 2 screwed. The connection arrangement 3 also has a body-side guide element 5 on, which with the spring-side guide element 4th cooperates. As especially in the detailed representations in 3 and 4th can be seen, is the spring-side guide element 4th as a housing 4.1 formed, which laterally has two guide slots 4.2 has, which together have a guide route F. define. The guide slots 4.2 and thus the route F. are straight in the embodiment shown and extend in the direction of the X-axis of the vehicle, although they generally do not run parallel to this. The body-side guide element 5 has an axillary element 6th on that, for example. Can be formed by a screw with a nut 11 is secured. A sleeve element 7th sits on the axilla 6th and is about a first pivot axis A. pivotable, which is the central axis of the axle member 6th corresponds. Both the axilla 6th as well as the sleeve element 7th are along the first pivot axis A. through both guide slots 4.2 passed through.

A coil spring 8th is in the case 4.1 of the spring-side guide element 4th recorded and between this and the sleeve element 7th intermediate. With normal axle load, as in 1 and 3 shown is the coil spring 8th with the spring-side guide element 4th and the sleeve element 7th in contact, but almost or completely relaxed. This changes as the axle load increases, as in 2 and 5 shown. The longitudinal leaf spring 2 goes into a convexly curved state, increasing the distance between the front end 2.1 and the rear end 2.2 decreased along the X-axis. A length compensation is therefore necessary, which takes place in that the two guide elements 4th , 5 are shifted against each other. More precisely, the two guide slots move 4.2 on the sleeve element 7th along, this translational displacement also from a rotation of the spring-side guide element 4th compared to the body-side guide element 5 (as well as the vehicle body 20th ) around the first pivot axis A. is accompanied. The displacement of the sleeve element 7th relative to the spring-side guide element 4th leads to the coil spring 8th is compressed, which in turn is associated with the generation of a restoring force. From the common deformation of the longitudinal leaf spring 2 as well as the coil spring 8th a progressive increase in the spring rate results.

It goes without saying that the increase in the spring rate is due to the material properties and the dimensioning of the helical spring 8th can be influenced. Alternative to the coil spring 8th An elastomeric element could also be used, for example a block made of rubber, which is compressed when the compression is increased. Under certain circumstances, it could be especially when the elastomeric element through the housing 4.2 is prevented from evading, the spring rate increases particularly sharply when the compression of the element approaches a material-related maximum value.

The increase in the spring rate can take place in particular in the manner of a two-stage suspension if the helical spring 8th is dimensioned shorter. This is exemplified using the embodiment in FIG 6th shown, which is essentially identical to that in 1 - 5 embodiment shown and is not explained again in this respect. 6th shows a normal load condition. The length of the coil spring 8th is chosen so that it is in this state from the sleeve element 7th is spaced and thus decoupled from this. The coil spring 8th can on the housing 4.2 of the spring-side guide element 4th attached or loosely attached to it. Alternatively, it would also be attached to the sleeve element 7th conceivable. As long as the axle load increases only slightly compared to the normal load, the coil spring will 8th not compressed, which means that the spring rate is exclusively due to the longitudinal leaf spring 2 is determined. The coil spring only comes into play from a certain axle load 8th with the sleeve element 7th in contact and is compressed in the further course. From this point on, the spring rate increases, which can be referred to as a two-stage suspension. It goes without saying that in this case too, instead of the helical spring 8th an elastomeric element could be used.

As if from the synopsis of 1 and 2 becomes clear, results from the compression of the vehicle axle 10 not just a vertical movement, but also a horizontal shift. This can at least be reduced if, as in the in 7th illustrated third embodiment, also at the front end 2.1 the longitudinal leaf spring 2 a connection arrangement 3 is provided. The two connection arrangements 3 at the front end 2.1 as well as at the rear end 2.2 are identical in the illustrated exemplary embodiment, but could alternatively also be designed differently. During compression, the length compensation takes place between the front end 2.1 and the rear end 2.2 via both connection arrangements 3 , wherein the spring-side guide element 4th at the front end 2.1 moves backwards with increasing compression, while the spring-side guide element at the rear end 2.2 moved forward. This results in an at least approximately purely vertical movement of the vehicle axle 20th possible.

List of reference symbols

1

Axle suspension

2

Longitudinal leaf spring

2.1

front end

2.2

rear end

3

Connection arrangement

4th

spring-side guide element

4.1

casing

4.2

Guide slot

5

on-site guide element

6th

Axillary element

7th

Sleeve element

8th

Coil spring

9

Pivot bearing

10

Rear axle

11

mother

20th

Vehicle body

A, B

Swivel axis

F.

Guide route

X

X axis

Z

Z axis

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• EP 3017211 B1 [0005]
• EP 2885554 B1 [0005]
• DE 102014005948 A1 [0006]
• DE 102016216149 A1 [0007]
• JP 2003335119 A [0008]
• DE 102010015951 A1 [0009]

Claims (10)

Axle suspension (1) for a vehicle, with a leaf spring unit (2) which extends in the longitudinal direction (X) of the vehicle and is supported on a vehicle axle (10) and at its ends (2.1, 2.2) is at least indirectly connected to a vehicle body (20), characterized by a connecting arrangement (3) arranged at a first end (2.2) of the leaf spring unit (2), with a spring-side guide element (4) attached to the first end (2.1) and a body-side guide element (5) connected to the vehicle body, on which the The spring-side guide element (4) can be displaced in a guided manner along a guide section (F) extending in the vehicle longitudinal direction (X) and is pivotable about a first pivot axis (A). Axle suspension after Claim 1 , characterized in that the connecting arrangement (3) has at least one reset element (8) interposed between the spring-side guide element (4) and the body-side guide element (5), which by shifting the guide elements (3, 4) against each other along at least part of the guide path (F) is elastically deformable. Axle suspension according to one of the preceding claims, characterized in that at least one restoring element (8) is designed as a spring or as an elastomer element. Axle suspension according to one of the preceding claims, characterized in that one guide element (4, 5) has at least one elongated guide recess (4.2) which defines the guide path and into which the other guide element (4, 5) engages and relative to which it is displaceable. Axle suspension after Claim 4 , characterized in that the spring-side guide element (4) has the at least one guide recess (4.2) into which the body-side guide element (5) engages, whereby it is guided along the body-side guide element (5) and displaceable. Axle suspension after Claim 5 , characterized in that the spring-side guide element (4) has a housing (4.1) in which at least one restoring element (8) is received and which has two guide recesses (4.2) spaced along the first pivot axis (A) through which the body-side guide element (5) is passed through. Axle suspension according to one of the preceding claims, characterized in that the body-side guide element (5) has an axle element (6) fastened to the vehicle body (20) and a sleeve element (7) rotatably mounted on the axle element (6) about the first pivot axis (A), which cooperates with the spring-side guide element (4) for guidance. Axle suspension according to one of the preceding claims, characterized in that at least one restoring element (8) is dimensioned in such a way that when the guide elements (4, 5) are displaced relative to one another along at least part of the guide path (F), at least one guide element (4, 5 ) is spaced and decoupled. Axle suspension according to one of the preceding claims, characterized in that the leaf spring unit (2) at the second end (2.1) is pivotably connected to the vehicle body (20) by a pivot bearing (9) about a second pivot axis (B). Axle suspension according to one of the preceding claims, characterized in that a connecting arrangement (3) is arranged at each end (2.1, 2.2) of the leaf spring unit (2).

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