DE19919845A1 - Wheel suspension, especially for steerable front wheels of commercial motor vehicles, has longitudinal links consisting of leaf spring steel with cross sectional dimensions larger in horizontal plane than in vertical plane - Google Patents

Abstract

Each of the suspension's longitudinal links(21) consist of leaf spring steel, the cross sectional dimensions of which are larger in the horizontal plane than in the vertical plane. The longitudinal links fit on the cross member and wheel axle and both are connected by a clamping screw arrangement. The longitudinal links by their free ends are supported on a lower face of the frame by at least one pneumatic spring(5). The intermediate support for attachment of the wheel carrier consists of a support shaft(31) rectangular in cross section for connecting to the guide frame, and a supporting and guiding bearing for the wheel carrier pivoting around a longitudinal axis.

Description

The invention relates to a wheel suspension, in particular for steerable Front wheels on vehicles with a vehicle frame, with a pair of trailing arms per pair of wheels, the two trailing arms to each other symmetrically on both sides of the vehicle frame stretch and swivel vertically on the frame in front of the axles of the wheels are guided bar and laterally immovable, with a cross member that extends across the vehicle between the two trailing arms and is firmly connected to them, so that together they Formation frame, and with an intermediate support per side for loading attach wheel carriers to the guide frame.

On commercial vehicles, it is common to have the front wheels on leaf springs keten below the laterally projecting arms of the frame support. The leaf spring assemblies are mostly in on both sides of the frame Arranged longitudinally of the vehicle and support together with wishbones located below the intermediate beams, which in turn have steering elements for steering that serve for the wheel carrier and transfer the respective part of the axle load to the wheel carrier.  

Such a suspension is highly unsatisfactory because because of the presence of the steering linkage and cross member the sheet springs arranged very high on the top of the intermediate carrier Need to become.

The frame, the drive unit and thus the driver's cabin must be positioned relatively high. To ensure a sufficient appropriate stability of the vehicle in curves, on uneven road surfaces or in the field it is necessary to have such vehicles with a size equip their width. Due to this large width, it is often not possible Lich, narrow streets or narrow streets in the mountains with such to drive wide commercial vehicles.

This is particularly unsatisfactory, especially for fire departments, which do not reach certain fires due to the large width and can not intervene at all or only with delay.

The height of these vehicles is similar. Conditionally due to certain standard dimensions of drive units, gears Such vehicles often have ben, driver's cab and superstructure Height that their use z. B. not allowed in underground car parks.

Another disadvantage of this arrangement is the spring characteristics Stik of the leaf spring packages. Their spring properties are mostly unreliable peaceful for the occupants of the driver's cabin.

Their relatively high height and lateral instability require rule moderate additional anti-roll bars for the front wheels.

DE 195 37 573 A1 is another wheel suspension for front der bicycles became known. For the purpose of retrofitting an additional front wheel drive modified the front one Suspension. The suspension of the wheel carriers takes place here in the for Cars usual way with wishbones and two above arranged wishbones. Under the frame and under one  A one-piece transverse leaf spring is arranged in the gear arrangement. This The transverse leaf spring is supported at two points that are far apart at the bottom of the axle beam. The free ends of the cross blade springs rest on the wishbones near the wheel bearing.

With such an arrangement it is only possible to a limited extent, the heavy point of the vehicle to be arranged relatively low. The immediate one Attaching the cross leaf spring to the frame means that the Driving through uneven terrain the vehicle tilts or ver twists.

A considerable disadvantage here is that the cross leaf spring offers unsatisfactory driving comfort.

Does the unevenness in the area of the rear wheels differ from that in the The area of the front wheels strongly and the frame can make this difference due to its flexibility no longer take up. Lift individual wheels away from the road. It can be the steering or the drive in be undesirably disturbed.

This makes this suspension especially for front wheels of a commercial vehicle is still unsatisfactory.

DE 198 08 172 A1 describes a wheel suspension, which should be used for both front and rear wheels. Such a suspension is then only described for unguided rear wheels.

The wheel suspension consists of trailing arms attached to the frame a transverse axis pivotally and axially immovable are. The trailing arms on both sides of the vehicle are connected by a cross member to each other by welds. As a result, the two trailing arms and the cross member form together a highly rigid lead frame.  

Already on wheel suspensions for rear wheels are occasionally lateral forces put so much strain on these welded joints that they tear frequently. As a rule, the suggestions there also help not constrictions.

On the front wheels, these lateral loads occur due to the constant against steering movements to an increased extent. There is obviously that Reason to look for such wheel suspensions for steerable Front wheels were used rarely or not in practice.

The object of the present invention is to propose a simple wheel suspension for vehicles,

• - which can also be used for steerable front wheels,
• - which enables the framework and thus the focus of the To arrange the vehicle very low and
• - Which makes it possible to use springs that have a much better quality Shafts as leaf spring assemblies or have one-piece leaf springs.

According to the invention this object is achieved by the de Finished wheel suspension solved surprisingly. The execution Trailing arm made of broad leaf spring steel and the clamping screw ben connection between cross member and the trailing arms creates a extremely stable guide frame for the front wheels, which is necessary dimensions is also elastic. The front wheels also follow a un level ground without the vehicle tilting excessively and / or that the frame twists.

The front wheels do not require additional lateral stabilization. The sufficiently flexible on the one hand and on the other very stable frame allows you to use the known air springs, that have clear advantages in terms of driving characteristics. The arrangement of the cross member at the height of the wheel axles, the Füh  trailing arms below this height and the use of drawbars elements between trailing arm and cross member or intermediate member creates the conditions for lowering the frame and for Use of smaller diameter wheels.

The springs, here the air springs, can be arranged in one area be located at the axle height of the wheels and outside the Swivel range of the wheels.

The height of the vehicle is significantly lower and the weight point can be lowered further. With the lower in this way The framework and focus can also be seen in commercial vehicles develop with a smaller width, the relatively large loads in narrow Lanes or on narrow roads in the mountains. Overall, the structure of the wheel suspension according to the invention is very high simple. Many standard parts can be used. Many items can can be made from semi-finished products with little effort.

Wheel suspensions of this type are also suitable, but not exclusive Lich, for vehicles that are only built in small series.

The features of claim 2 allow the intermediate carrier in insert the connection between trailing arm and cross member that the intermediate carrier alone is able to support the wheel carrier even at high To keep the load in the necessary position.

Add the support shaft of the intermediate beam between the trailing arm and cross member - according to claim 3 - with, the elasticity of this Connection can also be improved.

The connection of the intermediate beam with the guide frame after Claim 4 makes a decisive contribution to increasing the permissible axle load at.

The embodiment according to claim 5 helps to reduce the vehicle mass and creates the conditions for optional installation an additional front wheel drive according to claim 6.  

The design of the bearing of the trailing arms on the vehicle frame according to claim 7 supports the flexibility of the management framework, so that these also adapt to larger bumps in the floor can.

The adaptation of the steering gear to the conditions of the wheel suspension gung according to claim 1 has the subject of claim 8. He grants does that against all possible movements of the front wheels no unwanted changes of the Steering of the wheels triggered by extreme bumps the.

The arrangement of the shock absorber according to claim 9 makes it possible to be placed very close to the supporting frame. Cantilevered on the side Frame parts for the upper bearing of the shock absorbers are unnecessary. This arrangement also fits into the measures to lower the Focus.

The features of claims 10 and 11 allow the advantages with regard to the reduced height and the lower gravity point and the properties of the air springs on vehicles too use that have independent suspension and where the travel the wheels are significantly larger.

The invention will be explained in more detail below using an exemplary embodiment. In the associated drawings, FIG. 1 shows a simplified schematic representation of the front frame portion of a utility vehicle, wherein the interim were's support and the wheel carrier omitted for the sake of clarity,

Fig. 2 is a simplified plan view of the front axle,

Fig. 3 is a view of the front axle from the rear,

Fig. 4 is a perspective view of a lead frame with attached subcarriers

Fig. 5 is a view analogous to FIG. 4, in which the cross-member from the housing of a differential gear and of the tubular end pieces is formed, in which the drive shafts to be freely guided for the front wheels,

Fig. 6 shows a simplified vertical section along the transverse support axis from the connecting portion of the Führungsrah mens to the wheel carrier, in an embodiment according to FIG. 5,

Fig. 7 is a section through the connecting portion Guide # approximately frame transversely to the axis of the crossbeam,

Fig. 8 shows a section through the bearing of a trailing arm and

Fig. 9 is a schematic representation of the assignment of an air suspension trailing arm to an independent suspension with wishbones and wishbones for the wheel carrier.

In Fig. 1 the front part of a vehicle is shown. On the front side of the vehicle there is a drive unit, not shown, on the frame 1 . It is followed by the indicated gear 11 , which transmits the drive movement to the driven wheels of the vehicle via a propeller shaft 12 .

The wheel suspension for the steerable front wheels 13 , 13 ′ essentially consists of the guide frame 2 . This guide frame 2 has two trailing arms 21 , 21 ', which are mounted vertically pivotably on the bearings 211 , 211 ' in the front region of the frame 1 . These bearings 211 , 211 'are designed to be transverse to the longitudinal axis of the vehicle. They have a silent bushing 2111 shown in FIG. 8 in longitudinal section, which enables these bearings to have a certain elasticity about the longitudinal axis of the trailing arms 21 , 21 '.

The trailing arms 21 , 21 'as a whole consist of strong (12 to 20 mm) leaf spring steel. Their width in the horizontal direction is significantly larger than the vertical dimensions of the cross section. These trailing arms 21 , 21 'are directed backwards and slightly downwards in the first section. They carry the so-called cross member 22 in a central section. The cross member 22 is connected to the trailing arms 21 , 21 'by means of a clamping screw connection 23 in the form of so-called spring vapors 231 . With their arcuate sections, these spring vapors 231 encompass the cross member, the U-shaped supporting shaft 31 of an intermediate member 3 to be described later, almost in a form-fitting manner and also include the full cross section of the trailing arm 21 (see FIG. 7). A lower clamping plate 232 completes the clamping screw connection 23 . Two spring vapors 231 are provided in the area of each trailing arm 21 , 21 '.

Behind this connecting section with the clamping screw connection 23 , 23 ', the trailing arms 21 , 21 ' are preferably slightly cranked upwards and are then supported by air springs 5 on lower surfaces of the frame 1 .

Between the cross member 22 and the air springs 5 can be arranged close to the cross member 22 and preferably in the plane of the respective longitudinal link 21 , 21 ', a shock absorber 8 , which is supported with its upper bearing on the frame 1 .

In Fig. 1, the parts for guiding the wheels were omitted for better understanding. We can now recognize these elements in their spatial assignment in FIG. 2. Braced together with the cross member 22 on the trailing arm 21 and guided on this positively, the so-called. Intermediate carrier 3 with its U-shaped support shaft 31st

This intermediate carrier 3 has at its wheel carrier 4 th end facing a fork-shaped support and guide bearing 32nd

The axis, the steering axis 321 of this support and guide bearing 32 is inclined tool from bottom to top center of the vehicle and to the rear side of the driving and serves to guide the wheel support 4 in the imple mentation of steering movements. The overhead bearing 422 in this case transfers the share of the axle load to the wheel carrier 4th

The wheel carrier 4 has the counterparts to the support and guide bearings 322 and 323 , the support bearing 422 and the guide bearing 423 between the support and guide bearing 32 .

A tie rod lever 43 is attached to the front of the base body of the wheel carrier 4 and is used to transmit the steering movement by means of a tie rod 7 to the opposite wheel carrier 4 'in the manner of a parallelogram.

Another, in the middle position approximately parallel to the axis of the cross member 22 aligned steering lever 44 protrudes toward the center of the vehicle. In the front area of the frame 1 near a bearing 211 of a trailing arm 21 , the steering gear 6 is arranged above this bearing 211 . As shown in FIG. 1, this steering gear 6 is driven by the steering wheel 60 . Means for steering power amplification can be provided in the steering gear 6 , which need not be shown and described here.

In this case, the output member of the steering gear 6 is a short steering control lever 61 , which in its central position is directed approximately in the direction of the bearing 211 of the trailing arm 21 . The movement of the steering control lever 61 is transmitted to the steering lever 44 of the wheel carrier 4 via a steering rod 62 , which is provided on both sides with ball joint heads 621 , 621 'and whose length can be adjustable.

This arrangement of the steering gear 6 and the transmission members makes it possible to transmit the steering movement to the steered wheels 13 , 13 'almost without errors.

Different height positions of the wheels 13 , 13 'in relation to the frame 1 do not necessarily lead to a faulty steering deflection.

In Fig. 3, the entire front axle is shown again in a view from behind. In this example, the shock absorbers 7 are arranged between the trailing arms 21 , 21 'and the wheel carriers 4 , 4 '. It has proven to be expedient to shift the trailing arms 21 , 21 'as far as possible in the direction of the wheel carriers 4 , 4 ', thereby additionally increasing the stability of the vehicle. In this case, the linkages for the shock absorber 7 can be provided within the longitudinal link 21 , 21 '.

In Fig. 4, the guide frame 2 with the two trailing arms 21 , 21 ', the transverse axis 22 , the connecting sections (clamping screw connections 23 , 23 ') and the two intermediate beams 3 , 3 'is shown again in perspective as a separate unit.

This Fig. 4 makes a principle of the present invention particularly clear. The formed by the trailing arms 21 , 21 'and the cross member 22 ge guide frame 2 has a very high stability with lateral loads. On the other hand, this guide frame 2 has sufficient flexibility, mainly in the vertical direction, so that each wheel 13 , independently of the other wheel 13 ', can follow the unevenness of the floor. This flexibility is ensured by the two clamping screw connections 23 , 23 ', by the torsional capacity of the trailing arm made of leaf spring steel 21 , 21 ' and possibly by the flexibility of the above-described bearings 211 , 211 'of the trailing arm 21 , 21 '.

None of the main parts of the guide frame 2 is weakened in the region of the clamping screw connections 23 , 23 'through bores or the like.

The transmission of power from the trailing arms 21 , 21 'to the cross member 22 by spring vapors 231 loaded under tension offers significant advantages. The force of the part of the axle load takes place in the lowest area of the wheel bearing 41 and leaves the area above free for the arrangement of steering linkages and drive axles and creates space for a lowered frame 1 . All points of the power transmission from the frame 1 to the trailing arm 21 are located on the underside of the frame 1 , the frame 1 only having to be at a distance from the cross member 22 which sufficiently corresponds to the maximum spring travel at this point.

In Fig. 5 a modified embodiment is shown schematically, in which the front wheels 13, 13 'of the vehicle will also receive a drive. The middle part of the cross member 22 is formed here by the housing of a differential gear 221 . The two end pieces 222 , 222 'of this housing are designed as guide tubes for the drive shafts 223 .

These drive shafts 223 have a joint 224 in the region of the steering axis 321 of each wheel carrier 4 , so that the drive movement can be reliably transmitted even with extreme steering movements.

All other components have the same function as they were described with reference to Fig. 4.

, Is shown in a section along the axis of the cross member 22, the area between the connecting portion 23 and the wheel 4 in Fig. 6. The tubular cross member - here the tubular end piece 222 - engages in a correspondingly matching bore of the intermediate carrier 3 and is also based on the cross-section U-shaped gene, towards the vehicle center supporting shaft 31 of the intermediate carrier 3 .

This supporting shaft 31 in turn lies with its flat base on the broad side of the trailing arm 21 . The cross member 222 , the support shaft 31 and the trailing arm 21 are pressed against each other by the spring vapors 231 and the clamping plate 232 and held stable. The necessary elasticity of the connection is ensured in particular by the elasticity of the spring vapors 232 themselves and by the substantially U-shaped cross section of the supporting shaft 31 .

The intermediate carrier 3 is fork-shaped in the left section. This fork-shaped part forms the support bearing 322 at the top and the guide bearing 323 at the bottom for the wheel carrier 4 .

Through the tubular cross member 222 , the drive shaft 223 is guided for one of the front wheels 13 in this case. It transmits its rotary movement via the universal joint 224 to the wheel to be driven.

The use of this suspension is of course not limited on vehicles with an apparently continuous front axle are provided.

FIG. 9 shows a variant in which the trailing arm 21 transfers its share of the axle load of the vehicle to the wishbone 34 of an individually mounted wheel 13 . The functions of the cross member 22 can in this case take over the combination of the central frame part 1 a and the two wishbones 34 .

To relieve these moving elements, however, it is advisable to additionally provide a cross member 22 at a distance from the wheel axle, which can then be connected to the trailing arms 21 , 21 'in the manner described above.

The front sections of the wishbones 34 facing the wheel here perform the function of an intermediate carrier 3 .

The support bearing 322 a of the wishbone 34 is supported on the support bearing 422 a of the wheel carrier 4 a.

The upper guide of the wheel carrier 4 a is carried out by a pair of wishbones 35 which guide the guide bearing 323 a articulated on both sides at a mutual distance. The two wishbones 35 can be flexibly connected to one another by a cross member (similar to FIG. 4).

Because of the different movement characteristics of the triangular link 34 and trailing arm 21 , rubber pads should be arranged between these parts.

From the highly schematic sketch it can be seen that in this case too the introduction and transfer of the proportional axle load to the wheel carrier 4 a takes place at a very low point. The space above this area is free for wishbones 35 , as well as for the elements for transferring the steering movement.

Of course, it is not absolutely necessary to arrange the trailing arm 21 a below the wishbone 34 . It is quite possible to run the same over the wishbone 34 so that it is supported by a rubber buffer on the top of the wishbone 34 .

One of the most important advantages of the present invention is that the axle load is introduced onto the wheel carriers below the wheel axle and that the spring, preferably an air spring with controllable air pressure, can be arranged in a region below the frame that includes the plane of the axle. The space immediately above the axle remains free for track and steering linkages and can be used to a considerable extent for further lowering the frame. It does not matter whether the cross member 21 (in the immediate area of the wheel axles) is designed as a continuous rigid body or is a rigid body connected to the frame, on which cross members are articulated.

Reference list

1

,

1

a frame

11

transmission

12th

propeller shaft

13

,

13

'' Wheels, front wheels

2nd

Lead frame

21

,

21

',

21

a Trailing arm

211

,

211

' Camp

2111

Silent rifle

22

Cross member

221

Differential gear

222

,

222

'End sections

223

,

223

a drive shaft

224

Universal joint

23

Clamping screw connection (connecting section)

231

Feather vapors

232

Clamping plate

3rd

Intermediate beam

31

Inertia

32

Support and guide bearings

321

Axle, steering axle

322

Support bearing

323

Guide bearing

33

Linkage for shock absorbers

34

Wishbone

35

Wishbones

4th

,

4th

a wheel carrier

41

Wheel bearings

42

Support and guide section

422

,

422

a support bearing

423

,

423

a guide bearing

43

Tie rod arm

44

Steering lever

5

,

5

'' Air spring

6

Steering gear

60

steering wheel

61

Steering control lever

62

Handlebar

621

,

621

'Ball joint head

7

Tie rod

8th

,

8th

'' Shock absorber

Claims (11)

1. wheel suspension, in particular for steerable front wheels on driving witnesses with a vehicle frame,
with a pair of trailing arms per pair of wheels, the two trailing arms extending symmetrically to each other on both sides of the vehicle frame and in front of the axles of the wheels on the frame men vertically pivoted and laterally immovable,
with a cross member which extends transversely to the vehicle between and is firmly connected to the trailing arms, so that together they form a guide frame,
with an intermediate carrier per side for fastening wheel carriers to the guide frame, characterized in that
that each of the trailing arms ( 21 , 21 ') consists of leaf spring steel, the cross-sectional dimensions of which are larger in the horizontal plane than in the vertical plane,
that the trailing arms ( 21 , 21 ') engage under the cross member ( 22 ) and the wheel axle and are both connected by means of clamping screw connections ( 23 , 23 ') and
that the trailing arms ( 21 , 21 ') are supported with their free ends on at least one air spring ( 5 , 5 ') on a lower surface of the vehicle frame. 2. Wheel suspension according to claim 1, characterized in
that the intermediate carrier ( 3 ) for fastening the wheel carrier ( 4 )

• - From a cross section of the external dimensions approximately rectangular supporting shaft ( 31 ) for connection to the guide frame ( 2 ) and
• - From a support and guide bearing ( 32 ) for the pivotable about the steering axis ( 321 ) wheel carrier ( 4 ).

3. Wheel suspension according to claim 1, characterized in
that the intermediate carrier ( 3 ) has a cross-sectionally U-shaped support shaft,
that the intermediate carrier ( 3 ) with this support shaft ( 31 ) between the cross member ( 22 ) and the trailing arm ( 21 ) in the region of the clamping screw connection ( 23 ) is fixed. 4. Wheel suspension according to claim 1 to 3, characterized in that the intermediate carrier ( 3 ) in the section near the support and Füh approximately bearing ( 32 ) which surrounds the wheel carrier ( 4 ) on both sides outside, immediately adjacent to the support shaft ( 31 ) has a bore for the positive reception of the cross member ( 22 ). 5. Wheel suspension according to claim 1 to 4, characterized in that the cross member ( 22 ) is tubular and is aligned with the axis of the wheels ( 13 ). 6. Wheel suspension according to claim 1, characterized in
that the cross member ( 22 ) is tubular in its central part as a housing of the differential gear ( 221 ) and at its end sections ( 222 , 222 ') and
that the drive shafts ( 223 ) are guided to the wheels ( 13 , 13 ') through the end sections ( 222 , 222 '). 7. Wheel suspension according to claim 1, characterized in that the bearing ( 211 , 211 ') of each trailing arm ( 21 , 21 ') on the frame ( 1 ) around the longitudinal axis of the trailing arm ( 21 ) is of limited flexibility. 8. Wheel suspension according to claim 1 and 2, characterized in
that the wheel carrier ( 4 ) is equipped with a tie rod lever ( 43 ) oriented approximately in the direction of travel and with a steering lever ( 44 ) oriented approximately parallel to the cross member ( 22 ),
that a steering gear ( 6 ) known per se is arranged near the bearing ( 211 , 211 ') of a trailing arm ( 21 ) and is equipped with a steering control lever ( 61 ) directed towards the bearing ( 211 , 211 ') of the trailing arm ( 21 , 21 ') and
that the steering control lever ( 61 ) of the steering gear ( 6 ) and the steering lever ( 44 ) of the wheel carrier ( 4 ) are connected to each other via a steering rod ( 62 ). 9. Wheel suspension according to claim 1 and 2, characterized in that the shock absorber ( 7 ) in each case near the connecting portion ( 23 ) of the guide frame ( 2 ) has its movable bearing and above it on the frame ( 1 ) has its fixed bearing. 10. Wheel suspension according to claim 1 and 2, characterized in
that the intermediate carrier ( 3 ) is designed as a component of a wishbone arm ( 34 ), to which two wishbones ( 35 ) arranged above it are assigned on the vehicle frame ( 1 ) and
that the trailing arm ( 21 , 21 ') is supported on the central section of the wishbone ( 34 ). 11. Wheel suspension according to claim 1 and 10, characterized in
that the trailing arm ( 21 , 21 ') engages under the wishbone ( 34 ) and
that the wishbone is supported by rubber buffers by means of a clamping screw connection (analog 23) with the trailing arm ( 21 ).