DE102014115894A1 - Longitudinal leaf spring with shackle - Google Patents

Abstract

The present invention relates to a longitudinal leaf spring arrangement (3) for a motor vehicle comprising a longitudinal leaf spring (4) which is coupled at one end (5) via a fixed bearing (6) with a rotational degree of freedom and at an opposite shackle end (7) relatively pivotable with a shackle (8) is coupled and the shackle (8) is coupled to a fixed bearing (6) with a rotational degree of freedom, wherein indirectly or directly to the longitudinal leaf spring (4) is coupled a Kraftfahrzeugachskomponente, which is characterized in that between the shackle end (7) and the shackle (8) is formed a shackle angle (α), wherein the shackle angle (α) in compression or rebound in an angular range predetermined by a circular sector (13) moves, wherein at least two thirds (18) of the circular sector (13) in an angle greater than 90 degrees.

Description

The present invention relates to a longitudinal leaf spring arrangement for a motor vehicle according to the features in the preamble of patent claim 1.

Motor vehicles are nowadays mainly produced with self-supporting bodies or ladder frames with attached body. On these bodies or ladder frame axles are arranged so that the motor vehicle wheels against the vehicle body can rebound or rebound so as to accommodate dynamic wheel loads and thus to ensure the road contact between the wheel and the road surface and on the other to realize a ride comfort.

For this purpose, systems of springs and dampers are provided to suspend, for example, an independent suspension or even a rigid axle relative to a motor vehicle body spring. For this purpose, coil springs, air springs but also leaf springs are installed on motor vehicles.

For example, is from the DE 102 02 114 A1 a longitudinal leaf spring assembly is known, wherein the longitudinal leaf spring is connected via a shackle to a chassis to assist the attachment of the spring to the vehicle body. By varying the thickness or width, and thus the cross section of the longitudinal leaf spring, the spring characteristic can be modified in the desired manner.

Furthermore, from the DE 195 24 106 A1 a leaf spring assembly is known, in which one end of a longitudinal leaf spring is suspended by means of a shackle to compensate for changes in length during compression and rebound of the wheel.

Object of the present invention is, starting from the prior art, to provide a longitudinal leaf spring arrangement in which a targeted influencing of the spring characteristic is possible.

The aforementioned object is achieved with a longitudinal leaf spring arrangement according to the features in claim 1.

Advantageous embodiments are the subject of the dependent claims.

The longitudinal leaf spring assembly according to the invention for a motor vehicle has a longitudinal leaf spring which is coupled at one end via a fixed bearing with a rotational degree of freedom and is coupled to an opposite Schäkelende relatively pivotable with a shackle and the shackle is in turn coupled to a fixed bearing with a rotational degree of freedom. A motor vehicle axle component is coupled indirectly or directly to the leaf spring.

The longitudinal leaf spring arrangement according to the invention is characterized in that a shackle angle is formed between the shackle end of the longitudinal leaf spring and the shackle, wherein the shackle angle during compression or rebound moves in an angular range predetermined by a circular sector, wherein at least two-thirds of the circular sector at an angle greater than 90 ° lie.

According to the invention not only a change in length of the longitudinal leaf spring is compensated for compression or rebound, but due to the targeted position of the shackle in all imaginable operating situations a change in height of the shackle end of the longitudinal leaf spring is made simultaneously. This change in height of the shackle end ensures that at the same deflection of the wheel in relation to the vehicle body, an initially smaller and then larger compression travel is made, which is why more spring force acts on the axle. As a result, in particular the spring characteristic of the longitudinal leaf spring is influenced in such a way that it progresses progressively.

Under the shackle end of the longitudinal leaf spring is an end piece, which extends in the longitudinal direction of the longitudinal leaf spring to understand. Between this end piece and the shackle then a shackle angle is clamped. Depending on the curvature of the longitudinal leaf spring in compression and rebound this end piece can also be assumed as a tangent or fictitious longitudinal axis of the connection point between the shackle end of the longitudinal leaf spring and the shackle itself. Between these two then the shackle angle results. So that the inventive effect of the targeted influencing of the spring characteristic, in particular to a progressively extending spring characteristic is achieved according to the invention, the kinematic coupling and longitudinal leaf spring designed so that at least two-thirds of all assumed shackle positions give a shackle angle is greater than 90 °. For this purpose, the shackle angle moves in an angular range which is spanned by a circular sector. This means that in each case one side of the circular section or circular sector represents the maximum deflection of the shackle. In the spanned by this angle range of the shackle can then move during operation of the motor vehicle with occurring superposition of static and dynamic wheel load.

It is particularly preferred that all shackle angles taken during operation are greater than or equal to 90 °. Further particularly preferred are all assumed shackle angles greater than 100 ° and in particular greater than 110 °.

However, the angular range of the circular sector itself is in particular less than 180 °, preferably less than 160 °, in particular less than 140 °, particularly preferably less than 90 ° and very particularly preferably less than 50 °. For the latter value, this means, for example, that the circular sector extends from an angle range of 110 ° with 50 ° to 160 °. Furthermore, particularly preferably, the circular sector has less than 40 °, in particular less than 30 °, for the angular range which it spans.

This means that in each case the entire circular sector is designed such that a bounded side, which specifies a minimum assumed shackle angle, is such that it is greater than or equal to 90 ° or greater than 100 ° and in particular greater than 110 ° and then all during operation assumed shackle angle between the shackle end of the longitudinal leaf spring and the shackle itself are greater than the above values.

This results in a spring characteristic of the longitudinal leaf spring, which has a progressive course. The spring characteristic of the actual longitudinal leaf spring with conventional shackle connection can already have a progressive course, in which case a progressive progression is further enhanced by the shackle connection according to the invention.

A preferred embodiment variant of the present invention provides that the longitudinal leaf spring in the unloaded state has a curved course, in particular on the motor vehicle vertical direction a curved downward course. Furthermore, particularly preferably, the longitudinal leaf spring also has a curved profile which is curved downwards in the vertical direction of the motor vehicle when the wheel load is static.

A further preferred embodiment variant provides that in a previously named downwardly curved longitudinal leaf spring due to a Einfederungsvorganges at a time an ideal rectilinear course of the longitudinal leaf spring is present. If the longitudinal leaf spring continues to be subjected to a dynamic wheel load by this rectilinear course, the course initially curved downwards would change into an upward curved course. In this straight-line course, the shackle angle is greater than or equal to 90 °, preferably greater than 100 °, in particular greater than 110 °. The ideal straight-line course of the longitudinal leaf spring does not occur in practice, however, because in carrying out the Einfederungsvorganges always in the arms of the longitudinal leaf spring different voltages, which cause at least locally, if not over the whole, at least in a section of the longitudinal leaf spring, curvatures. Further compression, thus a curvature upwards then leads in turn to a shortening of the longitudinal leaf spring in the longitudinal direction and thus to a larger shackle angle. The same applies to a rebound.

A further preferred embodiment variant of the present invention provides that a change in length of the longitudinal leaf spring in the vehicle longitudinal direction, also referred to as motor vehicle X direction, always leads to a change in height of the shackle end of the longitudinal leaf spring relative to the motor vehicle vertical direction, also referred to as motor vehicle Z direction leads. With the exception of this, in the case of a longitudinally extending leaf spring running in a straight line, the point in time of the swinging from downwardly curved course to upward curved course, since in this moment of time the height change is equal to zero.

With particular preference, a one-piece longitudinal leaf spring is used. By means of the construction according to the invention by means of shackles, it is thus possible to dispense with leaf spring arrangements known from the prior art in which a plurality of leaf springs are stacked on top of one another. The manufacturing costs and the maintenance costs decrease significantly. Particularly preferred is a longitudinal leaf spring made of fiber composite material used, but it can also be a longitudinal leaf spring made of a metallic material can be used.

Furthermore, the longitudinal leaf spring may have a cross section which is different from one another in the longitudinal direction. Thus, the longitudinal leaf spring in its longitudinal direction may have a different width and / or height.

The ends of the longitudinal leaf spring thus the free end and the shackle end, preferably have bearing eyes, which are then coupled by means of fastening bolts and / or separate bearings on a fixed bearing with a rotational degree of freedom or the shackle. For this purpose, the longitudinal leaf springs can be coupled to an axle auxiliary frame or else directly to the vehicle body or at the Schäkelende then the Schäkelende is coupled to the shackle and coupled the opposite end of the shackle then turn with a rotational degree of freedom with a Achshilfsrahmen or the vehicle body. Especially preferred for this purpose can also be used rubber-metal bearings in order to possibly damp vibrations due to the excitation by the road surface. In the vehicle transverse direction, however, the system is designed to be parallel.

Preferably, the longitudinal leaf spring arrangement according to the invention can be attached to an independent wheel suspension but also to an entire axle, be formed for example on a rigid axle. For this purpose, a longitudinal leaf spring arrangement is preferably formed on each motor vehicle side.

The wheel center of the wheel undergoes a deliberate change in height in the form of Radhubs by the input and Ausfederungsvorgang. Due to the change in length of the longitudinal leaf spring with respect to the suspension of the wheel itself, the wheel center would also move in the vehicle longitudinal direction, which d is negligible in the context of the invention.

Furthermore, the longitudinal leaf spring is divided into two arms. At the connection point of a motor vehicle axle thus extending in the direction of travel, an arm of the longitudinal leaf spring forward to the connection and an arm to the rear to the connection. The arms particularly preferably have a mutually different length. Also, by choosing the position of the axle connection thus Festlegubng the length of the arms, it is thus possible to influence the spring characteristic to the desired extent.

Further advantages, features, characteristics and aspects of the present invention are the subject of the following description. Preferred embodiments are shown in the schematic figures. These are for easy understanding of the invention. Show it:

1 an inventive spring characteristic with respect to a linear spring characteristic,

2a to c the longitudinal leaf spring arrangement according to the invention in different compression states and

3a to d circle sectors according to the invention the shackle angle over the prior art.

In the figures, the same reference numerals are used for the same or similar components, even if a repeated description is omitted for reasons of simplicity.

1 shows an inventively progressive spring characteristic 1 opposite to a linear spring characteristic 2 , It is marked on the X-axis of the traveled compression travel z and on the Y-axis, the resulting spring force F. It can be seen that the progressive spring characteristic 1 initially has a softer suspension property up to the intersection point S, compared to the linear spring characteristic 2 , From the point of intersection S, the progressive progression increases to such an extent that a greater spring force F3S is available at the compression travel Z3, compared to the linear spring characteristic curve 2 in which the force F3 of small F3S is available at the compression stroke Z3. In contrast, the progressive spring characteristic according to the invention 1 softens at a lower compression travel Z1 and has a spring force F1S, compared to the linear spring characteristic 2 , which has a larger force F1 on the compression path Z1.

This is achieved with the longitudinal leaf spring arrangement according to the invention 3 , presented in the 2a reached to c. For this purpose, a longitudinal leaf spring 4 provided, which extends in motor vehicle X direction x. The longitudinal leaf spring 4 is doing with a rotational degree of freedom with one end 5 at a camp 6 stored. The camp 6 For example, it can be arranged directly on the motor vehicle body or on an axle auxiliary frame.

The opposite shackle end 7 is relatively pivotable with a shackle 8th stored. The shackle 8th itself is again at a fixed camp 6 stored with a rotational degree of freedom. It can also be seen that the longitudinal leaf spring 4 according to the motor vehicle vertical direction z curved curve downward 2a having. This preferably corresponds to the embodiment variant when the longitudinal leaf spring arrangement is acted upon 3 with static wheel load.

Furthermore, a wheel center 9 illustrated, wherein the axle or axle suspension, not shown, directly or indirectly on the longitudinal leaf spring 4 are coupled. Between the shackle end 7 and the shackle 8th a shackle angle α is formed. The in 2a shown unit circle shows the shackle angle α, starting from 90 ° plus the angle β. Thus, the shackle angle α here is about 130 ° to 140 °.

In 2 B becomes the longitudinal leaf spring arrangement 3 now loaded with a dynamic wheel load, so that the wheel center is moved to the motor vehicle vertical direction z up, which is equal to a compression process. The illustrated horizontal dot-dash line 10 corresponds to the vehicle body, so that the resulting distance between the wheel center 9 of the wheel 19 and dot-dash line 10 the wheel hub 11 equivalent. The distance between the dashed line 17 and wheel center 9 corresponds to the distance traveled 12 , travel 12 and wheel lift 11 are the better overview shown laterally offset from each other, but each go from the wheel center 9 out.

In 2a thus becomes a smaller spring travel 12 over the associated Radhub 11 kilometer. As a result, less spring travel 12 and more wheel stroke 11 according to time in 2a can be seen, the spring at the Schäkelanbindung invention at this time a lower spring force. At the time of jounce Z1 off 1 is the representation in 2a shown. The 2 B just before, with the shackle connection according to the invention suspended leaf spring and the leaf spring intersect with linear characteristic corresponds to the Einfederungsweg Z2 in 1 , Further compression of the collected with the Schäkelanbindung invention longitudinal leaf spring 4 thus ensures passage of the Radmittelpunktes 9 by the dash-dotted line 10 what the intersection S according to 1 equivalent.

Thus, it is easy to see that according to 2c a greater travel 12 opposite the associated Radhub 11 is covered, in relation to the dot-dash line 10 to wheel center 9 , Consequently, the spring is more compressed and thus has a higher spring force F. The shackle angle α always has more than 90 °. The smallest shackle angle α is in the in 2 B approximately flat configuration of the longitudinal leaf spring 4 shown, but here is still more than 90 °. Due to the fact that the shackle angle α is particularly preferably more than 90 ° in accordance with the invention, the change in height associated with the change in length in motor vehicle X-direction x is in the motor vehicle vertical direction of the shackle end 7 the longitudinal leaf spring 4 correspondingly large, so that the dependent therefrom covered travel 12 in relation to the Radhub accordingly in the direction of a progressive spring characteristic 1 is moved. Further shown in 2 B is that the longitudinal leaf spring 4 in the longitudinal direction of the wheel center 9 looked, two arms 4.1 . 4.2 having. The poor 4.1 . 4.2 have a mutually different length. By further length, it is also possible specifically to influence the suspension properties and also, for example, a S-blow at compression and rebound of the longitudinal leaf spring 4 to compensate. The wheel center 9 is doing for a longitudinal leaf spring 4 adjoining axle axis connection not shown selected to the mutually different length of the arms 4.1 . 4.2 the longitudinal leaf spring 4 to illustrate their respective connection.

3a to 3d show a respective circular sector 13 in which the shackle 8th can take a position and then forms a shackle angle α with the longitudinal leaf spring, not shown. In 3a is a Schäkelstellung known from the prior art. The circular sector 13 is bounded on the left side 14 , so that a maximum shackle angle α results and bounded on the right side 15 , so that a minimum shackle angle α results. The shackle end 7 experiences a movement in the motor vehicle X-direction x, which is indicated by ΔX, and a height change caused thereby in the motor vehicle vertical direction Z, which is indicated by ΔZ.

According to the invention is now according to 3b provided that the shackle angle α between shackles 8th and shackles 7 as in 3b represented at least 90 °, so that the circular sector 13 shifted so that when reaching the right-hand edge 15 between shackles 7 and shackles 8th an angle of 90 ° (α = 90 ° + β, where β = 0) and upon reaching the left-hand edge 14 a significantly larger shackle angle α, in particular of up to 140 ° or 150 ° or higher.

It can be seen that a significantly greater height change in motor vehicle vertical direction z shown by .DELTA.Z results, with smaller length extension .DELTA.Z in the vehicle longitudinal direction.

3c shows an alternative variant, here is the circular sector 13 in which the shackle is 8th moves, so moved that at least two-thirds 18 the area of the circular sector 13 give a shackle angle greater than 90 °. The shackle angle α can thus be as in the right-hand edge 15 can be seen, even assume a value less than 90 °, for example up to 88 °, 87 ° or even 85 °. Two-thirds 18 the captive angular positions of the shackle 8th However, give a shackle angle greater than 90 °. Here, too, with a comparable or smaller linear expansion ΔZ in the vehicle X direction x, there is a greater change in height in the vehicle vertical direction ΔZ than in FIG 3a illustrated prior art.

Finally, a particularly preferred embodiment is in 3d shown, after which the entire circular sector 13 in an angular range from greater than 100 °, in particular greater than 110 °. This means all between the shackles 8th and the shackle end 7 An acceptable shackle angle α is at least 100 ° or more. The illustrated right-sided edge 15 thus has a shackle angle α of 100 ° or more, wherein the left-hand edge 14 then a shackle angle α over 110 °, preferably 120 °, in particular includes over 130 °. In this case, a particularly large change in height is further recorded by .DELTA.Z, with relatively small displacement of the position in the longitudinal direction with .DELTA.X.

LIST OF REFERENCE NUMBERS

1

progressive spring characteristic

2

linear spring characteristic

3

Longitudinal leaf spring assembly

4

Longitudinal leaf spring

5

End to 4

6

fixed bearing

7

Shackles too 4

8th

Shackles

9

wheel center

10

 dot-dash line

11

 Rasthub

12

 travel

13

 circular sector

14

 left edge

15

 right edge

16

Fixed storage too 8th

17

 dashed line

18

two thirds of 13

19

 wheel

F

 spring force

S

intersection

x

Motor vehicle X direction

z

 Spring travel in the Z direction

z

Automotive vertical direction

α

 shackle angle

β

 Auxiliary angle (α = 90 ° + β)

.DELTA.Z

 Height change in Z direction

.DELTA.X

 Height change in the X direction

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been 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.

Cited patent literature

• DE 10202114 A1 [0004]
• DE 19524106 A1 [0005]

Claims (10)

Longitudinal leaf spring arrangement ( 3 ) for a motor vehicle having a longitudinal leaf spring ( 4 ), which at one end ( 5 ) about a fixed camp ( 6 ) is coupled with a rotational degree of freedom and at an opposite shackle end ( 7 ) relatively pivotable with a shackle ( 8th ) and the shackle ( 8th ) at a fixed camp ( 6 ) is coupled to a rotational degree of freedom, wherein indirectly or directly on the longitudinal leaf spring ( 4 ) a Kraftfahrzeugachskomponente is coupled, characterized in that between the Schäkelende ( 7 ) and the shackle ( 8th ) a shackle angle (α) is formed, wherein the shackle angle (α) in compression or rebounding in a by a circular sector ( 13 ) predetermined angular range, with at least two-thirds ( 18 ) of the circular sector ( 13 ) are at an angle greater than 90 degrees. Longitudinal leaf spring arrangement according to claim 1, characterized in that all angles in the angular range are at least greater than or equal to 90 degrees. Longitudinal leaf spring arrangement according to claim 1 or 2, characterized in that all angles are at least greater than 100 degrees, in particular greater than 110 degrees. Longitudinal leaf spring arrangement according to one of the preceding claims, characterized in that the spring characteristic of the longitudinal leaf spring ( 4 ) is progressive and / or that the spring characteristic ( 1 ) of the longitudinal leaf spring arrangement ( 3 ) is progressive. Longitudinal leaf spring arrangement according to one of the preceding claims, characterized in that the longitudinal leaf spring ( 4 ) in the unloaded state has a curved course, in particular on the motor vehicle vertical direction (z) has a downwardly curved course. Longitudinal leaf spring arrangement according to one of the preceding claims, characterized in that, in the case of a longitudinally extending leaf spring running in a straight line as a result of a suspension process ( 4 ) the shackle angle (α) is greater than or equal to 90 degrees, with subsequent compression or rebounding resulting in a larger shackle angle (α). Longitudinal leaf spring arrangement according to one of the preceding claims, characterized in that a change in length (.DELTA.X) of the longitudinal leaf spring ( 4 ) always to a change in height (ΔZ) of the shackle end ( 7 ) leads. Longitudinal leaf spring arrangement according to one of the preceding claims, characterized in that the longitudinal leaf spring ( 4 ) is formed of fiber composite material, in particular in one piece and uniform material. Longitudinal leaf spring arrangement according to one of the preceding claims, characterized in that the cross section of the longitudinal leaf spring ( 4 ) is different from one another in the longitudinal direction. Longitudinal leaf spring arrangement according to one of the preceding claims, characterized in that the longitudinal leaf spring ( 4 ) of an axle connection in the longitudinal direction with two arms ( 4.1 . 4.2 ) is projecting, wherein both arms ( 4.1 . 4.2 ) have a different length from each other.

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