GB2258903A

GB2258903A - Vehicle suspension

Info

Publication number: GB2258903A
Application number: GB9217200A
Authority: GB
Inventors: Thomas Gehrlich; Georg Horn; Hans-Hermann Keller; Gerhard Schilling; Dieter Lange; Eberhard Wagner
Original assignee: Daimler Benz AG; Mercedes Benz AG
Current assignee: Daimler Benz AG
Priority date: 1991-08-21
Filing date: 1992-08-13
Publication date: 1993-02-24
Also published as: ITRM920611A1; DE4127616C1; FR2680486A1; ITRM920611A0; JPH05208606A; GB9217200D0

Description

I -,?-) 3?IS 4-) 1 Vehicle The invention concerns a vehicle with a shock

absorber whose upper end is supported on a body-side abutment and which carries a vibration damper held flexibly in its axial direction.

Vehicles are known with shock absorbers which are combined with a vibration damper. Both low frequency body vibrations and higher frequency axle vibrations can be damped by means of such shock absorbers in that in order to damp body vibrations, vibration energy is extracted by the vibration damper from the shock absorber which i s introducing forces into the body.

In a known design in accordance with German OIL f enlegungsschrif t 22 37 058, the piston of the hydraulic shock absorber also acts as the vibration damper and is suspended so that it can vibrate on the shock absorber tube -he unsprung masses. "he shock absorber tube fastened to 41- L AJ slides in turn in a guide tube connected to the sprung masses and is designed as the damper piston for attenuating the vibrations of the sprung masses.

In consequence, an integrated shock absorber damping both masses is involved and from the design point of view, this can only be realised with corresponding complexity.

In another known type in accordance with the German 0j.lfenlegungsschrift 39 13 528, the vibration damper is fastened externally in the shock absorber tube in such a way that a damper mass encloses, completely or partially and with clearance, the periphery of the tube. The vibration damper again, therefore, requires much space in the radial direction of the shock absorber tube. In consequence, the installation space necessary for the accommodation of shock absorbers of the two known types is often not available in vehicles.

Also common to the two known types of shock absorbers the fact that the vibration damper is fastened at the i s t wheel end and the unsprung wheel mass is therefore increased 2 in the subcritical matching range.

The present invention seeks, therefore, to propose a vehicle damper arrangement which can be achieved without space problems and with no ef f ect on the unsprung wheel mass.

According to the invention there is provided a vehicle with a shock absorber having an upper end supported on a body-side abutment and which carries a vibration damper flexibly held in its axial direction, wherein the piston rod of the shock absorber passes through the abutment on the vehicle body and the vibration damper is located on the end part of the piston rod passing through the abutment.

In a design according to the invention, the vibration damper is therefore provided outside the space existing between wheel and body and accommodating the components of the wheel suspension, i.e. it is provided on the end of the body-side shock absorber abutment remote from the shock absorber itself. The vibration damper is decoupled by this means from the body and is directly coupled to a part of the axle which excites vibrations. By this means, vibrations introduced by a wheel can be effectively damped in a frequency-selective manner. The direct coupling of the vibration damper to the shock absorber makes it possible to achieve the damping effect with a correspondingly small damper mass because the vibration damper can then absorb vibration energy before it is introduced into the body. A particular advantage is the fact that the unsprung wheel mass is not increased by the vibration damper.

Because the damper mass primarily used for damping high-frequency wheel vibrations can then be made correspondingly small, it can be advantageously accommodated in a body space available above the abutment, the body-side fixing of the shock absorber being available as a fastening or bolting point to hold the damper mass. The engine compartment, which is easily accessible, is particularly suitable for this purpose.

Particular advantages of the invention also consist in 1 1 3 the -Eact that it offers the possibility to retrofit a vibration damper to shock absorbers in motor vehicles without difficulty so that both pitch and torsional vibrations of the body can be effectively damped. A substantial advantage of the invention is that it nay then be sufficient particularly in the case of open vehicles with relatively low body torsional stiffness - to equip only one of the shock absorbers (particularly on the front axle) with a vibration damper in the manner according to the invention.

An embodiment of t_he invention will now be described by way of example with reference to the drawing, in which:

Fig. 1 shows a diagrammatic representation of an open sports cabr4Lolet with the engine coin, part-ment partially exposed, shows the construction of the absorber/,'da-j,,per unit in a diagrarnmatic representation, shows a possible arrange-ren-IL-- of the vibration damper in combination with a partially represented suspensLon strut axle, Fig. 4 show various embodiments of the vibration to 6 damper in diagrammatic representation.

In the sports cabriolet shown in Fig. 1, the body 10 is supported at the axle end by suspension struts 11, for example (Fig. 2). In the present case, only one of these suspension struts on the front axle shown in Fig. 2 (having, for example, individual wheel suspensions) has, preferably, the construction according to the invention.

In the individual wheel suspension having the suspension strut 11, tt-he road surface is indicated by 12 and the mass of the wheel and the parts vibrating with the wheel when the suspension is deflected (which form the components of the relevant individual wheel suspension) are indicated by 16.

A spring system consisting of the tyre springing 18 and the tyre damping 20 is 'Located between the road surface 12 and the wheel mass 16. A shock absorber 22, on the one Fig. 2 Fig. 3 4 hand, and a helical spring 23, on the other, are inserted between the wheel mass 16 (and the other masses vibrating with it) and the vehicle body 10. A shock absorber strut could be present instead.

Shock absorber 22 and helical spring 23 have spring support on an elastically flexible abutment 24 held in a suspension dome 21, the end part 251 of the piston rod 25 of the shock absorber 22 passing through the abutment 24 and carrying a vibration damper 28 on this end part 251; the vibration damper 28 consists of a damper mass 30, a spring 32 and a shock absorber 34.

therefore located within the The vibration damper 28 is engine compartment 36 of the vehicle body 10, where it is easily accessible and sufficient space is available for its accommodation.

in such a motor vehicle in which there is no roof to increase the stiffness of the body 10, torsional vibrations of the body about the vehicle longitudinal axis are usually generated when the vehicle is in no'--ion because the body 10 is excited to vibration via the shock absorbers of the suspension struts, which act as the vehicle front axle components introducing the forces. Such torsional vibrations of the body are perceived by the vehicle occupants as socalled transverse judder.

By using the suspension strut 11 described, with vibration damper 28 tuned to the critical body torsional frequency, the natural frequency of the vibration system which includes the individual wheel suspension in addition to the shock absorber 22 supported on the body - is detuned during driving in such a way that the body 10 will no longer vibrate in resonance because the vibration damper 28 absorbs vibration energy before it is introduced into the body.

A preferred arrangement of the vibration damper 28 is shown in Fig. 3. In this, the damper mass 30 is elastically suspended, by means of rubber spring elements 48 and 50, between the arms 42 and 44 of a U-shaped stop stirrup 46 applied in known manner to the piston rod end part 251.

In the embodiment shown in Fig. 4 of the vibration r, damper 28, the latter has a rubber spring element 38 in the of a circular cylinder, for example, the spring element 38 being bolted onto the end part 251 of the piston rod 25 by means of a threaded sleeve 40 vulcanised into the spring element 38. on its upper end surface, the spring element 38 carries the damper mass 30, which matches the shape of its periphery. The damper mass 30 can also be made annular, for example, as shown in Fig. 5 and can be vulcanised onto the periphery of the spring element 38 which has the shape of a circular cylinder.

As shown in Fig. 6, a design variant can consist in giving the spring element 38 an elongated shape and dividing the damper mass 30 in such a way that a mass part 301 or 3011 is provided at each end face of the spring element 38.

shane 6

Claims

A vehicle with a shock absorber having an upper end supported on a bodyside abutment and which carries a vibration damper flexibly held in its axial direction, wherein the piston rod of the shock absorber passes through the abutment on the vehicle body and the vibration damper is located on the end part of the piston rod passing through the abutment.
2. A vehicle according to Claim 1, wherein the shock absorber is part of an independent wheel suspension and a body space accommodating its end part including vibration damper is the engine compartment.
3. A vehicle according to Claim 1, wherein the damper mass of the vibration damper is elastically supported.
4. A vehicle according to Claim 3, wherein the damper mass is located on the side of a holding element remote from the shock absorber end part.
5. A vehicle according to Claim 3, wherein a holding element extends at right angles to the shock absorber axis and carries a damper mass at each of its ends.
6. A vehicle according to Claim 3, wherein a holding element is discshaped and the damper mass is annular and encloses the holding element.
7. A vehicle according to Claim 3, wherein a holding element is a Ushaped stop stirrup fastened to the upper piston rod end part, the damper mass being elastically suspended between the arms of the U-shaped stop stirrup.
8. A vehicle substantially as described herein with reference to and as illustrated in the accompanying drawings.

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