DE3408940A1 - LENGTH SHAFT FOR MOTOR VEHICLES - Google Patents

Description

- -:. ::. - - '- LOO6 7.OOO

The invention relates to a propshaft for motor vehicles with a tubular shaft part, at each end of which a joint is attached is.

Cardan shafts predominantly have a sliding part that allows length compensation, e.g. when assembling or readjusting the rear axle drive and / or made possible by the rear suspension. The sliding part is guided mechanically, e.g. by means of a spline or a splined shaft profile. In addition, torsionally flexible cardan shafts are known in which an elastic layer is provided in addition to the mechanical sliding part. By activating the elasticity, shocks from the engine can be avoided keep away, dampen irregularities and the natural frequency of the drive train keep away from dangerous resonance areas. Finally, it is also known to have the cardan shaft with a multi-plate clutch running in oil to combine. The space requirement in the radial as well as in the axial direction caused by this coupling represents in addition to the increased weight is a considerable disadvantage.

The invention is based on the object of creating a cardan shaft which enables length compensation. Furthermore, strong Irregularities in the torque introduced into the shaft are dampened, especially torque shocks are kept away from the engine. This task should in particular be solved without requiring additional space, i.e. the Means for solving the problem are without increasing the shaft diameter to be accommodated in the PTO shaft. Finally, it should be possible, depending on requirements, to fix the wavelength to a given level set or under the action of an axial force damped length

LOO67.OOO

allow changes. Further advantages result from the following Description.

According to the invention, this object is achieved in the aforementioned longitudinal shaft in that the tubular shaft part through formed at least one tube attached to the socket of the one joint and at least one tube attached to the socket of the other joint is, the outer diameter of one tube is smaller than the inner diameter of the other tube, the tubes to form at least one Annular gap are arranged telescopically one inside the other, at least the annular gap or the annular gap between the tubes with a viscous Medium are filled and the annular gap enclosed by the outer tube is sealed to the outside at the pipe end. The tubes, which are concentric after assembly, have between them a tubular layer of the viscous, Medium or several such tubular layers. The torque introduced into the cardan shaft is transferred from the drive-side tube transfer the layer of the viscous medium to the output-side pipe, the layer of media being subjected to shear stress. The width of the annular gap and thus the layer thickness of the medium, the viscosity of the medium and the size of the effective shear surface (s) formed by the tubes are preferably selected so that the torque without significant speed difference of the pipes is transmitted. Accordingly, will generally with small gap widths of the order of <1 mm,

L.

Media of high viscosity and large shear surfaces worked. On the other hand

the selection can be made so that in the event of discontinuities in the transmitted Torque or torque surges that one pipe is accelerated in relation to the other. Shear work is done by the shaft.

*) continue on page 6a

": - ^: ·:: \ LQ057; .. 9.OO

~ 8B - —r

*) The formation of the shear surfaces and the selection of the medium can be made so that with small speed differences only a small torque and with larger speed differences a high torque can be transmitted. This type of function can be used with an all-wheel drive Replace the vehicle with a center differential. The order according to the invention takes on the task of a self-locking differential.

LUC6 7,000

and the discontinuity smoothed or the shock dampened. In the same The cardan shaft has a dampening effect in the event of axial impacts, since the relative movement of the pipes in the longitudinal direction also consumes shear energy will. Around the quasi-rigid coupling between the drive part and the driven part of the cardan shaft up to the maximum torque required To achieve this, the effective shear area is to be brought to the required size by pulling in several interlocking pipes. At a A preferred embodiment are two concentric tubes interlocking with one another to form three annular gaps on both joint stubs scheduled. The drive shaft according to the invention is characterized by a small radial space requirement, i.e. the shaft diameter is not larger than that of a conventional cardan shaft with a steel tube as the shaft part. The weight and price of the shaft is less than that of a combination of conventional cardan shaft and multi-plate clutch.

In a preferred embodiment of the shaft according to the invention, the interior of the inner tubes is at least partially with filled with the viscous medium. The annular gap or the annular gaps between the tubes of the cardan shaft are in terms of flow with the interior of the shaft connected so that the medium can flow from the gap to the interior space and from the interior space into the annular gap, if this is due to the change in length the shaft is required.

In one embodiment, the part of the interior of the inner tube that is filled with the medium is provided by a Pressure-resistant wall separated from the part of the interior that is not filled with medium. Through this wall in the interior, that is stored there

-LCQ 6.7,000

Guaranteed volume of the medium kept constant. Because a change in length the shaft is connected to an inlet or a displacement of medium from the annular gap or the annular gaps, is connected to the through the The stationary wall also achieved constant volume in the interior Fixed length of the PTO shaft. In this particular embodiment, the free end of the outer tube on the socket of the adjacent Joint also be mechanically attached. Changes in length are excluded in this embodiment; you can only use one joint, be added specifically to a constant velocity sliding joint.

In a further development of this embodiment of the invention can be equipped with a pressure relief valve to the outside in the joint, which rests against the medium-filled part of the interior be formed leading channel. While the length of the cardan shaft over the filling amount of the medium in the entire interior or through the stationary, pressure-resistant wall closed off part of the interior is fixed, if the medium pressure rises above a specified, If necessary, open the overpressure valve at an adjustable value and thus the medium can flow outwards. This will make the determination the wavelength is canceled, so that the tubes are again longitudinally displaceable relative to one another while absorbing shear energy.

With conventional cardan shafts, strong axial shocks, e.g. caused by rear-end collisions, can lead to not only is the front part of the vehicle damaged, but the impact force is also transmitted to the rear via the cardan shaft and thereby the rear axle and possibly the entire rear part of the vehicle are deformed

40-

jOO ti. 000

will. This is achieved by the arrangement of the outlet channel according to the invention avoided with the pressure relief valve. If as a result of an axial shock Medium pressure in the filled part of the interior of the shaft via a rises predetermined value, the viscous medium flows out to the outside. The axial displaceability is restored, with the contrary to a mechanical sliding part due to the shear forces to be applied considerable damping is effective. The axial shock is alleviated in the shaft, and that in the rear of the vehicle by shock Damage caused at least reduced. Of course it is also possible not to pass the duct with the pressure relief valve through the joint to the outside, but through the pressure-resistant wall to the part of the pipe interior that is not filled with medium. Because this room is filled with air, the medium can, if the pressure is high enough, without Difficulty draining into this part of the interior.

In another embodiment of the invention, the part of the interior filled with the viscous medium is covered by a bottom The wall that yields to the pressure of the medium is separated from the part of the interior space that is not filled with the medium. In this case the length is the PTO shaft only relatively fixed. To the extent that the wall gives way under the pressure of the medium, the length of the shaft can also increase change. In one embodiment, the wall that yields under the medium pressure is a piston that is displaceable in the inner tube. This Pistons, which are pressurized on one side by the medium and sealed against the inner tube, are under the action of a sufficient pressure of the medium Slidable in the inner tube. When sufficient axial forces act on the The length of the PTO shaft can therefore be changed. At another

, 095 7,000

* ΛΑ-

the embodiment of which is the wall when the medium pressure is increased rupturing membrane. Similar to a pressure relief valve, when a certain pressure is reached, the medium can enter the air-filled Overflowing space, the relative fixation of the wavelength is canceled. Appropriately, it is not filled with the viscous medium Part of the interior via a channel guided through the joint socket connected to the outside air. This ensures that the air-filled Part of the interior is always under atmospheric pressure.

Appropriately, are close to the two ends of the shaft part the longitudinal shaft between the free end of a tube or an abutment formed on this and the joint socket or arranged on an abutment formed on the other tube coil springs. The springs are used to keep the tubes in a central position to hold and to apply opposing forces in the event of compression or expansion of the shaft.

At least one joint of the longitudinal shaft according to the invention is preferably a constant velocity sliding joint. A change in length can are then not only received by the shaft part in the manner explained above, but also by the sliding joint. Included are expediently dynamic changes in length in the sliding joint, but on the other hand the large differences in length, e.g. due to vehicle tolerances are caused in the shaft part of the invention PTO shaft added. In addition, the joints are the prop shaft structured as usual, i.e. they are universal joints, equal joints or also rubber couplings.

-JH--

-H-

L0CE7.C00

3,089,0

The tubes of the propshaft can have uneven surfaces, Be provided with holes or slots. In this way, the entrainment of the viscous medium from the drive-side tube is increased and the Increased shear. A silicone oil, for example, which is available in very different viscosities, can serve as the viscous medium.

The invention is described in more detail below with reference to the drawing. The same parts also wear the same in all figures Reference numbers. Show it

FIG. 1 shows a first embodiment of the longitudinal shaft according to the invention, for the most part in axial section;

Figure 2 is a section along the line A-B of Figure 1;

FIG. 3 shows a second embodiment of the longitudinal shaft according to the invention, also in axial section;

FIG. 4 shows a third embodiment of the longitudinal shaft according to the invention in axial section; and

FIG. 5 shows a fourth embodiment of the longitudinal shaft according to the invention in axial section.

According to Figure 1, the cardan shaft consists of a shaft part 1 with a constant velocity sliding joint 2 at one end and a universal joint 3 at the other end. At the nozzle 2 ^{a of} the synchronizing

Sliding joint 2, two tubes 4 are welded concentrically. In a similar way ^, two tubes 5 are concentrically welded to the connecting piece 3a. The outer and inner diameters of the tubes 4, 5 are dimensioned in such a way that they - as shown - can be pushed into one another alternately, with a tubular annular gap 6 remaining between a tube 4 and a tube 5. The width of the annular gap 6 is, for example, 1 mm; the wall thickness of the tubes 4.5 is, for example, 1.5 or 2 mm. The inner tube 4 is bent outward at its free end at four diagonally opposite points in the form of tabs 4 ^a by the gap width. In the same way, the interior of the two tubes 5 is bent inward by the same gap width ^{at its free end at four diagonally opposite tabs 5 a.} In this way, mutual centering of the tubes 4, 5 and their central guidance in the event of relative axial displacement is achieved. The free end of the outer tube 5 is widened outwards at 5. The widening accommodates a sealing ring 7, which is guaranteed to remain in the widened area even when the tubes 4, 5 are displaced relative to each other by an upper throw ring 8. Since - as can be seen from Figure 2 - the bent tabs 5 ^a leave the gap 6 between them, all the gaps 6 with each other and the innermost of these annular gaps 6 are also connected to the interior 9 of the shaft part 1 in terms of flow. The entire interior, like the three annular gaps 6, is filled with a viscous silicone oil, whereby the length of the shaft part 1 is fixed.

In the embodiment shown in Figure 3, the interior of the shaft part 1 is by a displaceable piston 10 in a filled with the viscous medium part 9 ^a and not with the

LOOS 7,000

viscous medium filled part 9 separately. The piston 10 is sealed against the inner surface of the inner tube 4 ^{by a seal 10 a.} The part 9 of the interior is in connection with the outside air through the bore 11, so that the piston 10 is only acted upon by atmospheric pressure from the left, regardless of its position, while the respective pressure of the viscous medium is effective on the opposite side. The widening 5 of the outer tube 5 extends in this embodiment over an axially longer area. The upper throw ring 8 is attached to the pipe widening 5 and itself contains the sealing ring 7. In the area of the widening 5, an abutment 4 ^{C is} attached to the outer pipe 4. A helical compression spring 12 is arranged between the abutment 4 ^{C and the upper throw ring 8.} The outer tube 4 is provided at its free end with a radial bend 4; A helical compression spring 13 is also arranged between this bend and the joint 3 ^a. The springs 12, 13 hold the tubes 4, 5 in the illustrated central position, ie when the shaft part is stretched or compressed, the counterpressure of the spring 12 or the spring 13 becomes effective. When the length of the shaft part 1 changes, the shear forces required for the mutual longitudinal displacement of the tubes 4, 5, the force required to compress a spring 12 or 13 and the force counteracting the displacement of the piston 10 are to be applied.

In the embodiment of the cardan shaft shown in FIG. 4, the interior space is separated by a pressure-resistant wall 14 into the part 9 ^a filled with the viscous medium and the part 9 not filled with the viscous medium. The wall 14 is fixedly attached to the free end of the inner tube 4 and off by the sealing ring 14 ^a against the pipe

LQO67.000

sealed. This already provides a sliding fixation of the shaft part, since any compression or expansion of the shaft would put the medium under pressure or tension. In addition to this axial fixation, a fastening ring 15 is attached to the free end of the outer tube 5, which ^{engages over the joint 2 a} and also ensures the sealing of the outer annular gap 6 to the outside with the sealing ^{ring 15 a.} Since the ring 15 only ^{overlaps the connecting piece 2 a} , a relative rotation between the tubes 4 on the drive side and the tubes 5 on the output side is still possible.

The embodiment according to FIG. 5 differs from the embodiment according to FIG. 4 essentially in that the additional mechanical fixation by the fastening ring 15 is absent and an axial channel 16 equipped with an overpressure valve 16 ^{a , 16 is provided in the joint stub 3 a, which} leads from the medium-filled part 9 ^{a of} the interior of the propeller shaft to the outside. In this embodiment, the shaft member 1 is to a certain, predetermined maximum pressure of the medium is fixed in its length, the medium pressure this maximum value, for example, exceeds by an axial impact due to a collision, the valve 16 ^a, 16 opens. The viscous medium can thereby quickly ^{flow out of the volume 9 a} , the axial fixing of the pipe pairs 4 and 5 relative to one another is canceled, and the shaft part 1 can be compressed, with at least part of the impact energy being absorbed by the shear work in the pipe lamellas .

LO.O67.OCO

List of reference symbols

1 shaft part 16 channel

2 Equal displacement joint 16 ^a valve ball 2 ^{a connection} piece of the equal displacement joint 16 valve spring

3 universal joint

3 ^a socket of the universal joint

4 tubes
4 ^a tabs

4 radial tube bend 4 ^C abutment

5 tubes

5 ^a bent tabs

5 expansion

6 annular gap

7 sealing ring

8 upper throw ring

9 interior

9 ^a medi-filled part of the interior

9 Part of the interior not filled with medium

10 piston 10 ^a sealing ring

11 bore

12 helical compression spring

13 helical compression spring

14 wall 14 ^a sealing ring

15 fastening ^{ring 15 a} sealing ring

- blank page -

Claims (15)

LOO67.OOO Löhr & Bromkamp GmbH 6050 Offenbach Line shaft for motor vehicles Patent claims 1. longitudinal shaft for motor vehicles with a tubular shaft portion, each a hinge attached to the ends thereof, characterized in that the tubular shaft part (1) by at least one a joint (2) is translated to the connecting piece (2 ^a) of the tube (4) and at least one ^(a 3) of the other articulation (3) is translated tube (5) is connected to the socket formed, the outer diameter of the one tube (4) is smaller than the inner diameter of the other pipe (5), the tubes (4.5 ) are arranged telescopically one inside the other to form at least one annular gap (6), at least the annular gap or the annular gaps (6) between the tubes (4,5) are filled with a viscous medium and the annular gap enclosed by the outer tube (5) ( 6) is sealed to the outside at the pipe end. 2. Longitudinal shaft according to claim 1, characterized in that two concentric tubes (4 or 5) interlocking with one another with the formation of three annular gaps (6) are attached ^{to the two joint pieces (2 a} , 3 ^a). : -:: - - LOO67.OOO 3. Longitudinal shaft according to claim 1 or 2, characterized in that the annular gap width, the viscosity of the medium and the size the effective shear surface (s) formed by the tubes (4, 5) so selected are that the torque without significant speed difference of the tubes (4 and 5) is transmitted. 4. Longitudinal shaft according to one of claims 1 to 3, characterized in that the interior (9) of the inner tubes (4,5) is at least partially filled with the viscous medium. 5. Longitudinal shaft according to one of claims 1 to 4, characterized in that the part filled with the medium (9 ^a ) of the interior of the inner tubes (4,5) through a pressure-resistant wall (14) of the part not filled with the medium (9) of the interior is separated (Fig. 4). 6. Longitudinal shaft according to claim 4 or 5, characterized in that the free end of the outer tube (5 ^{) is mechanically attached to the socket (2 a} ) of the adjacent joint (2) (Fig. 4). 7. Longitudinal shaft according to one of claims 4 to 6, characterized in that in the joint (3 ^a ), which rests against the medium-filled part (9 ^a ) of the interior, one equipped with an overpressure valve (16 ^a , 16), according to outside leading channel (16) is formed. 8. Longitudinal shaft according to claim 4, characterized in that the part filled with the medium (9 ^a ) of the interior space by a wall which yields under the pressure of the medium of the not with the medium - '. "" - - """-" ■ '■ LOO6 7.OOO filled part (9) of the interior is separated (Fig. 3). 9. propshaft according to claim 8, characterized in that the wall is a piston (10) that can be moved in the inner tube (4) is (Fig. 3). 10. Longitudinal shaft according to claim 8, characterized in that the wall is a membrane which ruptures when the pressure of the medium increases. 11. Longitudinal shaft according to one of claims 8 to 10, characterized in that the part (9) of the interior which is not filled with the viscous medium is connected to the outside air via a channel (11) guided ^{through the joint (2 a) (Fig.} 3). 12. Longitudinal shaft according to one of claims 8 to 11, characterized in that close to the two ends of the shaft part (1) between the free end (4) of a tube (4) or an abutment formed thereon (4 ^C ) and the joint socket are placed (3 ^a) and one attached to the other tube (5) abutment helical compression springs (13 and 12) (Fig. 3). 13. Longitudinal shaft according to one of claims 1 to 12, characterized characterized in that at least one joint is a constant velocity sliding joint. 14. Longitudinal shaft according to one of claims 1 to 13, characterized characterized in that the tubes (4,5) with uneven surfaces, holes LOO67.OOO or slots are provided. 15. Longitudinal shaft according to one of claims 1 to 14, characterized characterized in that the viscous medium is a silicone oil.