DE102009020108B4 - Suspension for motor vehicles - Google Patents

Abstract

Wheel suspension for a motor vehicle, comprising a handlebar (18) articulated to the motor vehicle body (22) and pivotally connected to a wheel carrier (12) carrying a suspension spring element supported on the body (22), the force line of action (50) of Suspension spring element in the vehicle transverse direction is adjustable, wherein the suspension spring element is rotatably supported by means of interposed rotary plate (30, 32) on the handlebar (18) and on the structure (22), characterized in that the suspension spring element by two diametrically to the axis of rotation (M) of the turntable ( 30, 32) arranged springs (26, 28) is formed.

Description

The invention relates to a suspension for motor vehicles according to the preamble of claim 1 and a method for adjusting a spring rate of a suspension spring element in a wheel suspension according to claim 16.

Such a suspension describes, for example, the DE 25 38 103 A1 in which the compression of the body of the motor vehicle or to compensate for additional loads, the helical compression springs are adjusted between each link of the suspension and the construction of the motor vehicle. For this purpose, the springs are supported eccentrically on turntables, wherein the force of action line (spring center axis) is shifted more or less away from the pivot axis of the handlebar by turning the turntable. Thus, the spring hardness or preload force is changed, but not the spring rate. The off-center support also leads to a tension or torsional moments on the handlebar bearings.

To avoid such torsional features, it is by the DE 10 2006 049 726 A1 also known, the adjusting mechanism of the spring plate form such that the force lines of action of the springs linearly and substantially along the Lenkerlängsmittelachse emigrate.

From the DE 10 2004 058 698 B3 is a generic suspension known. This has a suspension spring element which is supported between turntables. The geometric spring center line of the suspension spring element is identical to the spring axis of rotation. The force action line is arranged at a distance ax parallel to the spring center line or tilted thereto. From the DE 39 21 710 A1 a further suspension for a motor vehicle is shown, in which the suspension spring element is formed from two springs. The two springs are not mounted on turntables, but on a linearly adjustable in the vehicle transverse direction spring plate and another spring plate, which is articulated via a rod in the vehicle transverse direction pivotally mounted on a handlebar.

The object of the invention is to propose a suspension of the generic type, which allows an advantageous influence on the spring characteristics of the suspension.

This object is achieved with the features of claim 1 or 16. Advantageous and expedient developments of the invention include the subclaims.

According to the invention, it is proposed that the suspension spring element is formed by two springs, in particular helical compression springs, arranged diametrically to the axis of rotation of the spring plate, whose force action lines can have at least substantially equal distances from the axis of rotation of the turntable. The two springs can have different spring rates D ₁ and D ₂ . These spring rates form with a corresponding adjustment of the two springs by changing the gear ratios i in a simple manner a variable Gesamtfederkonstante. Furthermore, it can be achieved by a suitable design of the two springs that their total spring constant can be adjusted to influence a defined driving behavior of the motor vehicle in more comfortable or more sporty.

The spring lengths of the two springs can be determined so that in the structural position of the suspension, the acting spring forces are the same. By rotation of the turntable, the spring ratios i ₁ and i _{2 are} changed. The force acting on the wheel remains the same, so that no height adjustment of the vehicle in the design point, that is in the design situation, takes place, but only changes the effective spring rate. In the design situation results in a predetermined predetermined vehicle weight at a predetermined vehicle weight.

In the above embodiment, the two springs may be biased in the construction position with equal force. If, on the other hand, the pretensions of the two springs differ in the construction position, an adjustment of level and effective spring stiffness can be achieved simultaneously by rotation of the turntable.

The ratio of level adjustment and spring hardness adjustment can be adjusted by selecting the initial parameters (spring rates and preload). By a stronger bias of the soft spring can be lowered at the same time the vehicle and the effective spring hardness can be increased.

By way of example, it is assumed below from a starting position (construction position) in which the soft spring in the transverse direction is outside and is strongly biased, while the hard spring inside, the means closer to the center of the vehicle, lies and is less biased: When the turntable is rotated, the soft spring is adjusted inwards and the hard spring outwards. In this way increases inside the bias, so that the vehicle is lowered altogether. The larger spring rate shifts to the outside, whereby the effective spring hardness increases.

Preferably, the force action lines of the two springs can pierce the handlebar longitudinal center axis in at least one design arrangement. This means that in a basic vote, the two springs are aligned in the vehicle transverse direction, so that one spring is closer and the other spring is further away from the handlebar pivot axis.

Furthermore, the lengths of the two springs can be designed such that in the construction position of the suspension (under design load) the acting spring forces F ₁ and F _{2 are the} same. As a result, with an adjustment of the two springs, the spring forces remain approximately the same, while changing the overall spring constant.

In particular, according to mathematical equation and possibly by empirical tests, the two springs can be tuned so that at a defined rotation of the turntable, the spring forces remain the same under design load and changes only the effective spring rate. In particular, the turntables can be adjustable over a rotation angle α of approximately 180 °.

The turntables can also be stored in a conventional manner via rolling bearings on the handlebar and on the body and be adjustable by means of at least one electric motor with a self-locking gear. Preferably, the electric motor and the gear can be arranged on the body-side turntable.

In a further embodiment of the invention, the suspension spring element can in particular be adjusted linearly along a longitudinal axis of the handlebar to change the spring stiffness, but not the vehicle height.

In the region of the adjustment of the suspension spring element, the handlebar support and the spring support can be aligned parallel to each other. In an adjustment of the suspension spring element therefore changes the spring ratio and thus also the spring force. Together with an associated change in length of the suspension spring element, this leads to an adjustment of the vehicle level.

By way of example, the rotational movement of the turntable via an adjusting gear can additionally be superimposed on a linear adjustment along the longitudinal axis of the handlebar. The combination of the rotational adjustment and a linear adjustment allows advantageous, further degrees of freedom in the structural design of the vehicle suspension, wherein in addition to the variable design of the spring rates and a height adjustment of the body is accomplished.

The adjusting mechanism can be formed in a particularly simple manner in terms of production engineering and construction, in each case by a stationary toothed rack and an external toothing on the turntable, wherein the turntable can be linearly displaced via a sliding guide with a displaceable sliding block serving as a rotary bearing for the turntable. However, the adjusting mechanism can alternatively also according to the above-mentioned DE 10 2006 049 726 A1 be executed.

Furthermore, in the construction position of the suspension in the region of the displacement of the suspension spring element, the link support relative to the body-side spring support not parallel, but be aligned converging or diverging. This represents another, structurally relatively simple measure to tailor the spring rate and the vehicle height depending on the design conditions. By a converging or divergent orientation of the handlebar support and the body-side spring support a height change of the vehicle can be amplified, attenuated or reversed.

Finally, the characteristic curve of at least one of the two helical compression springs can be designed progressive or degressive without any additional expenditure and in further specification of the spring properties via the occurring static and dynamic loads.

Two embodiments of the invention are explained in more detail below with further details. The schematic drawing shows in:

1 a rear view of a partially shown, rear wheel suspension for motor vehicles, with a lower wheel guide arm and two adjustable via turntable helical compression springs, which are supported on the structure of the motor vehicle;

2 a sketchy plan view of the lower arm according to 1 showing the spring assembly relative to the pivot axis of the handlebar;

3 a diagram of changing over the angle of rotation of the turntable spring hardness D _R to D _Rmax ;

4 a plan view of an alternative arrangement of the two helical compression springs on the handlebar of the suspension with an additional adjustment, which overlaps the rotational movement of the turntable a linear adjustment; and

5 a rear view of a suspension after 4 , in which, in the region of the linear adjustment of the helical compression springs, the lower link of the wheel suspension converges outwardly to the support surface of the helical compression springs on the superstructure.

In the 1 is roughly schematically a rear suspension 10 illustrated for motor vehicles, with one on a wheel carrier 12 rotatably mounted rear wheel 14 , At the wheel carrier 12 are an upper, only partially illustrated wishbone 16 and a lower, in construction position approximately horizontally oriented handlebars 18 via appropriate joints 20 hinged. Opposite are the handlebars 16 . 18 at the construction 22 the body of the vehicle pivotally mounted. It's just the pivot bearings 24 of the lower handlebar 18 seen.

At the lower handlebar 18 are two helical compression springs 26 . 28 as suspension springs with the interposition of a turntable 30 supported, at its upper end also with the interposition of a turntable 32 in the area of a longitudinal member 34 at the construction 22 issue.

The turntables 30 . 32 are about ring-shaped bearings 36 relative to the handlebar 18 and to the construction 22 rotatably mounted. In addition, the upper turntable 32 over a centric axis 38 with a self-locking gear 40 and an electric motor 42 connected by love.

The self-locking gearbox 40 can z. B. on the axis 38 be located worm wheel, which via a drive screw (not shown) of the electric motor 42 is driven and the turntable 32 adjusted over a defined rotation angle α. About the springs 26 . 28 becomes the lower turntable 30 mitverdreht accordingly. The electric motor 42 can be controlled via an electronic control unit (not shown) in accordance with driving dynamics parameters to adjust its spring characteristics (comfort or sporty).

The arrangement and design of the two springs 26 . 28 is related to 2 and by the lower, on the handlebar 18 arranged turntable 30 explained in more detail.

The total length I _{tot of} the handlebar 18 is defined by the hinge or pivot axes 44 . 46 of the handlebar 18 , The pivot point M of the turntable 30 has a distance I _m to the pivot axis 46 on and also lies in the longitudinal center axis 48 , in turn, by the not shown joint centers of the handlebar 18 certainly.

The two smaller in diameter than the turntable 30 executed, circular symmetrical springs 26 . 28 lie with their force line of action 50 diametrically at a distance I _e to the center M opposite. The on the turntable 30 exerted spring forces F largely compensate accordingly and practice neither a tilting moment on the turntable 30 nor a torsional moment about the longitudinal central axis 48 of the handlebar 18 provided the forces of the two springs 26 . 28 are about the same.

The feathers 26 . 28 are in the said construction position of the suspension 10 and at a defined load of the motor vehicle designed so that they have different spring rates D ₁ , D ₂ .

In addition, in this design state, the lengths of the two springs 26 . 28 determined so that the acting spring forces F ₁ , F _{2 are the} same.

By turning the turntable 30 . 32 by a defined angle α, preferably between 0 ° and 180 °, the spring ratios i ₁ and i _{2 are} changed because their force lines of action 50 to the pivot axis 46 of the handlebar 18 move.

The at the rear wheel 14 acting force remains the same, so that no height adjustment of the motor vehicle takes place in its construction position. The at the rear wheel 14 effective effective spring hardness D _R , however, changes according to the following equation: D _R = D ₁ i 2/1 + D ₂ i 2/2

It applies to the force F on the rear wheel 14 :

As a result, FR remains constant for all angles of rotation α, if, as stated, F ₁ = F ₂ (applies exactly only in the construction position with the handlebars aligned horizontally 18 ).

For the effective spring rate D _R applies accordingly:

The diagram according to 3 shows the qualitative course for D _R (effective spring rate) on the rotation angle α of the turntable 30 or the springs 26 . 28 receiving turntable 30 . 32 ,

By turning the turntable 30 . 32 via the self-locking gear 40 and the electric motor 42 and a corresponding shift of the force action lines 50 the springs 26 . 28 So can the effective spring D _R at the rear wheel 14 be adjusted continuously.

The 4 the drawing shows in a plan view of the handlebar 18 the suspension 10 an alternative embodiment, in which at the turntables 30 . 32 (it's just the lower turntable 30 visible) an additional adjustment 52 is arranged, the case of a rotation of the turntable 30 . 32 a linear displacement of the two helical compression springs 26 . 28 by a defined displacement s causes.

The adjusting mechanism 52 has a stationary rack 54 on the handlebar 18 is attached. The rack 54 is in engagement with an external toothing 56 at one with the turntable 30 firmly connected gear may be formed or as shown in simplified form on the turntable 30 is formed. The adjustment s at a defined rotation of the turntable 30 determined by the diameter of the external toothing 56 ,

The turntable 30 (or one with the turntable 30 connected gear) is in a sliding block 58 over a bearing axis 60 rotatably mounted. The sliding block 58 in turn is in a slot-shaped slotted guide 62 along the longitudinal axis 48 of the handlebar 18 slidably guided.

It should be noted that the turntable 32 on the structure of the motor vehicle is arranged analogously linearly adjustable and on the central axis 38 , the self-locking gearbox 40 and the electric motor 42 (see. 1 ) is rotatable.

Will the turntables 30 . 32 as described above z. B. by means of the electric motor 42 twisted, they are additionally on the stationary racks 54 as supporting organs and over their external teeth 56 along the slide tours 62 linearly displaced over the displacement s, wherein the distance between the central axis M, with the bearing axis 60 or the centric axis 38 the turntable 30 . 32 coincides, to the pivot axis 46 of the handlebar 18 changed accordingly.

In addition to the above-described change in the spring rates, this also causes an increase or decrease in the spring forces F ₁ , F ₂ , because the additional, linear displacement of the two springs 26 . 28 whose transmission ratio i ₁ , i ₂ additionally changed accordingly. The vehicle level can be raised or lowered accordingly.

The 5 shows a further variant of the influence of the spring forces F ₁ , F _{2 of} the two springs 26 . 28 in which the areas 18a . 22a the spring supports on the handlebar 18 and / or on the construction 22 of the motor vehicle does not look like 1 can be seen substantially horizontally and parallel to each other, but converging or diverging (see lines 64 . 66 ) are executed. Alternatively to the in the 4 and 5 shown embodiments, that of the two springs 26 . 28 be formed spring element also be designed as a single spring.

In the embodiment 5 is in the design position of the suspension 10 of the. Area 18a of the handlebar 18 inside, the handlebar bearing 24 too divergent with respect to the approximately horizontal area 22a of the construction 22 designed. As a result, with a linear displacement of the two springs 26 . 28 with their turntables 30 . 32 externally increases the spring preload and the vehicle level is raised.

An inverse effect is achieved when the areas 18a . 22a executed converging, whereby the vehicle level is lowered in an adjustment to the outside.

An additional possibility is the use of one or more springs with nonlinear spring characteristic (degressive or progressive spring). For example, in an arrangement in which the areas 18a . 22a running in the vehicle transverse direction outwardly converging, a progressive spring (spring rate is greater with the force used), a height adjustment of the vehicle can be done without changing the effective spring rate. So changes in an adjustment of the spring to the outside of the spring ratio. As a result, the spring force decreases, so that the suspension spring element is longer and the vehicle lifts.

Instead of the inclined area 18a on the handlebar 18 may also or alternatively the range 22a be designed appropriately inclined to the structure, depending on design and structural constraints or requirements.

By designing the inclined areas 18a . 22a more or less convergent or divergent additional constructive influence on the suspension properties can be exercised, and to an increasing extent the spring forces F ₁ , F ₂ and the total spring hardness can be varied depending on required driving characteristics under different load conditions of the motor vehicle.

At least one of the two helical compression springs 26 . 28 can also be designed with a non-linear characteristic (progressive or degressive).

For example, in a converging interpretation of the spring support surfaces 18a . 22a between the handlebars 18 and the construction 22 progressively designed helical compression springs 26 . 28 used with the spring travel increasing spring rate, a height adjustment of the vehicle can be done without changing the effective spring rate.

By a combination of the above-mentioned possibilities (two in the interpretation different helical compression springs 26 . 28 , additional linear displacement s, inclined support surfaces 18a . 22a , Nonlinear characteristics) is an optimization of the suspension and handling characteristics of the motor vehicle, in particular with regard to space, spring travel, minimization of the loading influence, etc. created, in the context of the invention, some or all of the possibilities described are exhaustible.

Claims (16)

Wheel suspension for a motor vehicle, with a vehicle body ( 22 ) articulated handlebars ( 18 ), which articulates with a wheel carrier ( 12 ) is connected and which carries a suspension spring element, the ( 22 ), the force line of action ( 50 ) of the suspension spring element in the vehicle transverse direction is adjustable, wherein the suspension spring element by means of interposed turntable ( 30 . 32 ) on the handlebar ( 18 ) and on the construction ( 22 ) is rotatably supported, characterized in that the suspension spring element by two diametrically to the axis of rotation (M) of the turntable ( 30 . 32 ) arranged springs ( 26 . 28 ) is formed. Wheel suspension according to claim 1, characterized in that the force action lines ( 50 ) of the springs ( 26 . 28 ) equal distances (I _e ) to the axis of rotation (M) of the turntable ( 30 . 32 ) exhibit. Wheel suspension according to claim 1 or 2, characterized in that the force action lines ( 50 ) of the two springs ( 26 . 28 ) in at least one design position, the handlebar longitudinal center axis ( 48 ). Wheel suspension according to claim 1, 2 or 3, characterized in that the two springs ( 26 . 28 ) have different spring rates (D ₁ ) and (D ₂ ). Wheel suspension according to one of the preceding claims, characterized in that the lengths of the two springs ( 26 . 28 ) are designed in an unloaded state such that in a constructional position of the suspension ( 10 ) the acting spring forces (F ₁ , F ₂ ) are the same. Wheel suspension according to one of claims 1 to 4, characterized in that the lengths of the two springs ( 26 . 28 ) are designed in the unloaded state such that in the construction position of the suspension ( 10 ) the acting spring forces (F ₁ and F ₂ ) are different, that is the springs ( 26 . 28 ) are subjected to different bias voltage. Wheel suspension according to one of the preceding claims, characterized in that the two springs ( 26 . 28 ) are tuned so that upon rotation of the turntable ( 30 . 32 ) The spring forces (F ₁ , F ₂ ) remain the same and only the effective spring hardness (D _R ) changes. Wheel suspension according to one of the preceding claims, characterized in that the turntables ( 30 . 32 ) are adjustable over a rotation angle (α) of 180 °. Wheel suspension according to one of the preceding claims, characterized in that the turntables ( 30 . 32 ) via rolling bearings ( 36 ) on the handlebar ( 18 ) and on the construction ( 22 ) are stored, and by means of at least one electric motor ( 42 ) with a self-locking gear ( 40 ) are adjustable. Wheel suspension according to claim 9, characterized in that the electric motor ( 42 ) and the transmission ( 40 ) with the body-side turntable ( 32 ) interact. Wheel suspension according to one of the preceding claims, characterized in that the suspension spring element along a longitudinal axis of the handlebar ( 48 ) is adjustable. Wheel suspension according to one of the preceding claims, characterized in that in a constructional position of the wheel suspension ( 10 ) in the region of the adjustment path (s) of the suspension spring element in the vehicle transverse direction, the handlebar support ( 18a ) and the body-side spring support ( 22a ) are convergent or divergent to each other. Wheel suspension according to one of the preceding claims, characterized in that the characteristic curve of the two springs ( 26 . 28 ) of the suspension spring element is designed progressive or degressive. Wheel suspension according to one of claims 11 to 13, characterized in that the rotational movement of the turntable ( 30 . 32 ) via an adjusting mechanism ( 52 ) a linear adjustment along the handlebar longitudinal axis ( 48 ) is superimposed. Wheel suspension according to claim 14, characterized in that the adjusting gear ( 52 ) by a stationary rack ( 54 ) and an outer toothing ( 56 ) on the turntable ( 30 . 32 ) is formed, wherein the turntable ( 30 . 32 ) via a link guide ( 62 ) with a sliding, as a pivot bearing for the turntable ( 30 . 32 ) serving sliding block ( 58 ) is linearly displaceable. Method for adjusting a spring stiffness of a suspension spring element in a wheel suspension according to one of the preceding claims.

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