JPH0114051B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a longitudinal axle for a motor vehicle, which has tubular shaft sections each having a joint at each end.

The joint axle usually has a sliding part by means of which a length compensation can be effected, for example, during assembly, during modification of the rear axle and/or during suspension of the rear wheel. In this case, the sliding part is guided mechanically, for example by splines. Furthermore, rotary elastic joint shafts are known which are provided with an elastic layer in addition to the mechanical sliding part. The addition of the elastic layer protects the drive mechanism from shock, dampens non-uniformities, and isolates the natural frequency of the drive line from dangerous resonance ranges. Furthermore, it is known to combine a disc clutch and a coupling shaft that operate in oil. The radial and axial space required by this clutch, along with the added weight, is a substantial disadvantage.

The object of the invention is to create a longitudinal axle for a motor vehicle with a joint shaft that can perform length compensation. A further aim is to damp strong inhomogeneities in the rotational torque introduced into the shaft and to protect the drive mechanism from special rotational torque shocks. In this case, the above objective must be achieved without increasing the required space. That is, it is necessary to attach a means for achieving the objective without increasing the diameter of the joint shaft. Furthermore, it must be possible to maintain the axial length at a given dimension or to tolerate damped changes in length under the action of axial forces, as required. Other advantages will be apparent from the description below.

The object of the invention is to provide a longitudinal axle of the type mentioned at the outset, in which a tubular shaft section is provided in one
consisting of at least one pipe installed on the stud of one fitting and at least one pipe installed on the stud of another fitting, the outside diameter of one pipe being smaller than the inside diameter of the other pipe. the pipes are nested within each other such that at least one annular gap is formed, the at least one annular gap or gaps between the pipes is filled with a viscous medium, and the outer pipe is filled with a viscous medium; This is achieved by sealing the thus enclosed annular gap from the outside at the pipe end. One or more tubular layers of viscous medium are formed between the concentric pipes after assembly. The rotational torque introduced into the joint shaft is transmitted from the driving side pipe to the driven side pipe through a layer of viscous medium, and at this time, the medium layer is
Subject to shear stress. The width of the annular gap, i.e. the layer thickness of the medium, the viscosity of the medium and the dimensions of the effective shear plane or planes formed by the pipes, is such that the rotational torque can be adjusted without any substantial difference in the rotational speed of the pipes. It is preferable to select such that the information is transmitted. Therefore, gap widths are generally <1 mm, large shear planes are constructed, and highly viscous media are used. The configuration of the shear planes and the selection of the medium are such that only small rotational torques can be transmitted when the rotational speed difference is small, and large rotational torques can be transmitted when the rotational speed difference is large. In all-wheel drive vehicles, this functional aspect replaces the central differential. in this case,
The device according to the invention serves as a self-locking differential. On the other hand, if the transmitted rotational torque is not constant or if rotational torque impulses appear, a choice can also be made such that one pipe is accelerated relative to another. In this case, the shear work is absorbed by the shaft, unsteadiness is smoothed out, and shocks are damped. In the event of an axial shock, the joint shaft likewise takes on a damping effect.
This is because a relative movement of the pipe in the longitudinal direction also consumes shear energy. In order to substantially rigidly couple the driving and driven parts of the joint shaft up to the required maximum rotational torque, an effective shear plane is formed by retracting a plurality of mutually engaging pipes by the required dimension. There must be. In a preferred embodiment, both fitting studs have two studs that engage each other to form three annular gaps.
Install two pipes. The joint shaft according to the present invention is
It is characterized by a small space occupied in the radial direction. That is, the diameter of the shaft is no larger than the diameter of a conventional joint shaft with a steel pipe as the shaft section. The weight and cost of the shaft is lower than conventional coupling shaft and disc clutch combinations.

In a preferred embodiment of the shaft according to the invention, the internal space of the inner pipe is also at least partially filled with a viscous medium. The annular gap or gaps between the pipes of the fitting shaft communicate with the internal space of the shaft, so that the medium flows from the gap through the internal space to the annular gap to the extent required for the length change of the shaft. can flow into the country.

In one embodiment, the part of the internal space of the inner pipe filled with medium is separated from the part of the internal space not filled with medium by a pressure-tight wall fixed to the pipe. Said walls of the internal space keep the volume of the medium stored in the internal space constant. Since the change in the length of the shaft is based on the inflow and outflow of the medium through one or more annular gaps, by keeping the volume of the internal space constant by immovable walls, the length of the joint shaft can also be adjusted. Fixed. In this particular embodiment, the free end of the outer pipe can also be mechanically fixed to the stud of the adjacent fitting. In this embodiment, length variations are eliminated. That is, length changes can be accommodated only by the joint (particularly the synchronous sliding joint).

In a further development of the above-described embodiment of the invention, the coupling stud adjoining the media-filled inner space part can be provided with a canal leading to the outside with a relief valve. The length of the coupling shaft is fixed depending on the media filling of the entire internal space or of the parts of the internal space separated by immovable pressure-resistant walls, but can be extended beyond a predetermined, possibly adjustable, value. increasing the medium pressure and opening the relief valve, thus
The medium can be drained. The fixed axial length condition is thus discarded, so that the pipes are once again able to slide relative to each other in the longitudinal direction under shear energy.

Furthermore, with conventional joint shafts, if the vehicle receives an axial impact due to a collision, for example, not only will the front of the vehicle be damaged, but the impact force will be transmitted rearward through the joint shaft. , thus the rear axle is deformed, and possibly even the entire rear part of the car. This disadvantage is eliminated according to the invention by providing an outflow canal with a relief valve. That is, when the medium pressure in the medium-filled portion of the internal space of the shaft exceeds a predetermined value due to an axial impact, the viscous medium flows out. It becomes possible to slide in the axial direction again. In this case, in contrast to mechanical sliding members, considerable damping occurs due to the applied shear forces. Axial impacts are cushioned within the shaft and damage to the rear of the vehicle resulting from the impact is at least reduced. of course,
The canal with the relief valve can also be led not to the outside through the coupling stud, but through the pressure-tight wall to a portion of the interior space that is not filled with medium. Since only air is present in this space, a medium at a sufficiently high pressure can easily flow into the interior space part.

In a further embodiment of the invention, the portion of the interior space filled with a viscous medium is separated from the portion of the interior space not filled with medium by a wall that deflects under the pressure of the medium. In this case, the length of the joint shaft is
It is only fixed conditionally. That is, the axial length can vary by the amount by which the wall deflects under media pressure. In one embodiment, the wall that is deflected by medium pressure is a piston that can be slid within the inner pipe.
This piston, which is sealed against the inner pipe and receives medium pressure on one side, slides in the inner pipe when subjected to sufficient medium pressure. Therefore, when an axial force is applied to the joint shaft, medium pressure is applied and the shaft length changes. In another embodiment, the wall is a membrane that ruptures when the medium pressure increases. As in the case of relief valves, the medium overflows into a space containing only air when a predetermined pressure is reached. In this case, the shaft length is no longer fixed. Preferably, the portion of the interior space not filled with viscous medium is communicated with the atmosphere via a canal passing through the coupling stud. Thus, the pressure in the interior space containing air is always atmospheric pressure.

In the vicinity of both ends of the axial portion of the longitudinal axle, compression is provided between the free end of one pipe and the coupling stud, and between the receivers constructed on said pipe and the receivers constructed on the other pipe, respectively. It is expedient to provide a coil spring. The spring serves to hold the pipe in a central position and to apply a counterforce to the shaft during compression or extension.

At least one joint of the longitudinal axle according to the invention is preferably constructed as a synchronous sliding joint. In this case, length changes are not only taken up by the shaft part in the manner described above, but also by the sliding joint. In this case, it is expedient to absorb dynamic length changes in the sliding joint, while large length differences, for example due to vehicle tolerances, are absorbed in the shank part of the joint shaft according to the invention. It is. Furthermore, the longitudinal axle joints may be of conventional construction (eg, universal joints, synchronous rotary joints, rubber joints).

The pipe of the longitudinal axle can be provided with uneven surfaces, holes or slits. The medium is thus driven more strongly by the drive-side pipe,
Shearing action is increased. As viscous medium, use is made, for example, of silicone oil, which is available with a wide variety of viscosities.

The invention will now be described in detail with reference to the accompanying drawings. In the drawings, identical parts have been given the same reference numerals.

As shown in FIG. 1, the joint shaft consists of a shaft section 1 provided with a synchronous sliding joint 2 at one end and a universal joint 3 at the other end. Two pipes 4 are concentrically welded to the stud 2a of the synchronous sliding joint 2. Similarly, two pipes 5 are welded concentrically to the stud 3a of the universal joint 3. The outer and inner diameters of each pipe 4, 5 are selected such that the pipes can be inserted into each other as shown.
When inserted, a pipe-shaped annular gap 6 is formed between each pipe 4 and pipe 5.
The width of the annular gap 6 is, for example, 1 mm, and the wall thickness of the pipes 4, 5 is, for example, 1.5 mm or 2 mm. The four diametrically opposed free ends of the inner pipe 4 are bent outwards by the width of the gap in the form of flaps 4a. Similarly, the four diametrically opposed flaps 5a of the free ends of both pipes 5 are
It is bent inward by the above gap width. Thus,
The pipes 4, 5 are mutually aligned and guided in an aligned manner when sliding relative to each other in the axial direction. The free end of the outer pipe 5 is expanded outwardly at 5b. The extension 5b receives the sealing ring 7. The sealing ring 7 is held within the extension by a sleeve ring 8 during relative sliding of the pipes 4 and 5. As is clear from FIG. 2, gaps 6 are formed between the bent flaps 5a, all the gaps 6 communicate with each other, and the innermost gap of the annular gaps 6 is further connected to the shaft portion. It also communicates with the internal space of 1. Throughout the interior space 9,
Like the three annular gaps 6, they are filled with viscous silicone oil, so that the length of the shaft part 1 is fixed.

In the embodiment shown in FIG. 3, the internal space of the shaft part 1 is divided into a part 9a filled with a viscous medium by a slidable piston 10 and a part 9b not filled with a viscous medium. It is divided into. The piston 10 is sealed against the inner surface of the inner pipe 4 by a packing 10a. Since the internal space portion 9b is in communication with the atmosphere via the bore 11, the piston 10, regardless of its position,
It receives atmospheric pressure only from the left side, while the opposite side receives
The pressure of the viscous medium acts. In this embodiment, the extension 5b of the outer pipe extends over a longer axial extent than the previous one. The sleeve ring 8 is fixed to the pipe extension 5b and includes a sealing ring 7. A receiver 4c is attached to the outer pipe 4 in the area of the expanded portion 5b. A compression coil spring 12 is provided between the receiver 4c and the sleeve ring 8. The free end of the outer pipe 4 is provided with a radially bent portion 4b. Similarly, a compression coil spring 13 is provided between this bent portion and the joint stud 3a. Springs 12 and 13 hold pipes 4 and 5 in the central position shown. That is, when the shaft portion 1 is compressed or expanded, a counterforce of the spring 12 or the spring 13 acts. That is, when the length of the shaft section 1 changes, the forces required for the longitudinal sliding of the pipes 4, 5 relative to each other, the forces necessary for the compression of the springs 12; 13 and the forces opposing the sliding of the piston 10 are applied. It will be done.

In the embodiment shown in FIG. 4, the internal space is divided into a part 9a filled with a viscous medium by means of a pressure-resistant wall 14 and a part 9 not filled with a viscous medium.
It is divided into b. The wall 14 is connected to the inner pipe 4
and is sealed against the pipe by a sealing ring 14a. The shaft part 1 is thus fixed. This is because when the shaft is compressed or expanded, the medium is subjected to pressure or tension. In addition to this axial fixation, a fixing ring 15 is attached to the free end of the outer ring 5. This fixing ring engages the coupling stud 2a and, together with the sealing ring 15a, seals the outer annular gap 6 from the outside. Ring 15 is
Since it only engages with the stud 2a, the driving side pipe 4 and the driven side pipe 5 can rotate relative to each other.

In the embodiment shown in FIG.
This embodiment differs essentially from the embodiment of FIG. 4 in that it is provided with relief valves 16a, 16b and an axial canal 16 leading from the medium-filled portion 9a of the interior space of the joint shaft to the outside. In this embodiment, the length of the shaft section 1 is fixed until the pressure of the medium reaches a predetermined maximum value. If the medium pressure exceeds the above-mentioned maximum value, for example due to an axial shock resulting from a collision, the valves 16a, 16b open. The viscous medium thus quickly flows out of the interior space portion 9a, the mutual axial fixation of the pipe pairs 4 and 5 is broken, and the shaft portion 1 becomes compressible. In this case, at least a portion of the impact energy is
Absorbed by shear work in the overlapping pipes.

[Brief explanation of drawings]

FIG. 1 is an axial sectional view of a major part of a first embodiment of a longitudinal axle according to the present invention, FIG. 2 is a sectional view taken along line A-B in FIG. 1, and FIG. FIG. 4 is an axial sectional view of the second embodiment, FIG. 4 is an axial sectional view of the third embodiment, and FIG. 5 is an axial sectional view of the fourth embodiment. 1...Shaft part, 2...Synchronous sliding joint, 2a...
Stud of synchronous sliding joint, 3...Universal joint, 3a
...Universal joint stud, 4...pipe, 4a...
...Flap, 4b... Radial bent portion of pipe, 4... Receiver, 5... Pipe, 5a... Bent flap, 5b... Expansion part, 6... Annular gap, 7
... Sealing ring, 8 ... Sleeve ring, 9 ...
Internal space, 9a... Internal space portion filled with medium, 9b... Internal space portion not filled with medium, 10... Piston, 10a... Sealing ring, 11... Bore, 12; 13... Compression coil spring , 14...Wall, 14a...Sealing ring, 15
...Fixing ring, 15a...Sealing ring, 16...
...Canal, 16a...Valve ball, 16b...Valve spring.

Claims (1)

[Scope of Claims] 1. In a longitudinal axle of a motor vehicle having pipe-shaped shaft parts each having a joint attached to its end, the pipe-shaped shaft part 1 comprises at least one pipe installed in the stud 2a of one joint 2. 4 and at least one pipe 5 installed on the stud 3a of another fitting 3, the outer diameter of each pipe 4 being smaller than the inner diameter of each other pipe 5,
the pipes 4, 5 are nested within each other so as to form at least one annular gap 6;
At least one annular gap or annular gaps 6 between the pipes 4, 5 is filled with a viscous medium and is surrounded by an outer pipe 5.
is sealed from the outside at the end of the pipe. 2. Claim 1, characterized in that both joint studs 2a, 3a are each fitted with two concentric pipes 4, 5 that engage with each other so as to form three annular gaps 6. Vertical axle as described. 3 Width of the annular gap, viscosity of the medium and pipe 4,
It is characterized in that the dimensions of the effective shear plane or surfaces formed by 5 are selected such that rotational torques are transmitted without substantial differences in the rotational speeds of the pipes 4, 5. A vertical axle according to claim 1 or 2. 4. The internal space 9 of the inner pipes 4, 5 is also at least partially filled with a viscous medium, as set forth in any one of claims 1 to 3. vertical axle. 5 The medium-filled portion 9a of the internal space of the inner pipes 4, 5 is protected by the pressure-resistant wall 14,
5. Longitudinal axle according to claim 1, characterized in that it is separated from the interior space portion 9b which is not filled with medium. 6. Longitudinal axle according to claim 4 or 5, characterized in that the free end of the outer pipe 5 is mechanically fixed to the stud 2a of the adjacent joint 2. 7 Relief valves 16a, 1 are installed on the joint stud 3a that contacts the internal space portion 9a filled with the medium.
6b and a canal 16 extending to the outside is formed. The vertical axle according to any one of claims 4 to 6. 8. Claim 1, characterized in that the interior space part 9a filled with a medium is separated from the interior space part 9b not filled with a medium by a wall that flexes under the pressure of the medium. Vertical axle as described in section. 9. Claim 8, characterized in that the wall is a piston 10 that can slide within the inner pipe 4.
Vertical axle as described in section. 10. Longitudinal axle according to claim 8, characterized in that the wall is a membrane that ruptures when the pressure of the medium increases. 11 Canal 1 through which the internal space portion 9b, which is not filled with viscous medium, passes through the coupling stud 2a.
The longitudinal axle according to any one of claims 8 to 10, characterized in that the longitudinal axle is in communication with the outside air through the longitudinal axle. 12 Near both ends of the shaft portion 1, there is a free end of one pipe 4 or a receiver 4c formed thereon.
A compression coil spring 1 is inserted between the joint stud 3a or a receiver attached to another pipe 5, respectively.
12. The vertical axle according to any one of claims 8 to 11, characterized in that the longitudinal axle is provided with: 3 and 12. 13. The longitudinal axle according to any one of claims 1 to 12, characterized in that at least one joint is a synchronous sliding joint. 14. The longitudinal axle according to any one of claims 1 to 13, characterized in that the pipes 4, 5 are provided with uneven surfaces or holes or slits. 15. The longitudinal axle according to any one of claims 1 to 14, characterized in that the viscous medium is silicone oil.