DE102015203991B4 - Closed hollow shaft - Google Patents

Abstract

Closed motor vehicle hollow shaft (10) for torque transmission with an outer wall (12) and an enclosed by this and the external environment sealed interior (11), and at least one local wall portion (16) on the outer wall (12), which at an increase of Pressure in the interior (11) of the hollow shaft (10) opens automatically as a discharge opening.

Description

The invention relates to a closed motor vehicle hollow shaft for torque transmission with an outer wall and an enclosed by this and the outside environment closed interior.

Hollow shafts are used, for example, in motor vehicles as part of a drive train to transmit torque. This makes it possible to reduce the total weight of the drive train and thus, for example, to reduce the power of a motor vehicle.

Since the moment of resistance of a pipe cross-section increases disproportionately with increasing average pipe diameter, high torques can be transmitted with large hollow shaft diameters even with small wall thicknesses and achieve low component weights.

To avoid corrosion, it is advisable to use a version that is closed to the outside environment with small wall thicknesses, so that corrosion protection measures can either be omitted or at least reduced from the inside.

The invention is based on the object to further improve such a closed hollow shaft.

For this purpose, it is proposed according to claim 1 to provide at least one local wall portion on the outer wall of a closed motor vehicle hollow shaft of the type mentioned, which automatically opens at a rise in the pressure in the interior of the hollow shaft as a discharge opening.

As a result, an excessive increase in pressure in the hollow shaft can be avoided. If there is an increased internal pressure, this can be reduced by providing the discharge opening in the outer wall.

Advantageous embodiments of the invention are the subject of further claims.

A relief opening can be created for example by a weakening of the outer wall and / or by a sealed opening. In the former case, there is a local perforation of the outer wall at overpressure, while in the second-mentioned case, the seal is canceled. In both cases, preferably the overall structure of the hollow shaft is substantially maintained, i. H. the relief opening exposed in the overpressure case occupies only a very small and virtually negligible proportion of the total surface area of the hollow shaft.

A corresponding local wall section may, for example, have a reduced wall thickness relative to the outer wall surrounding it, in order to open at a defined internal pressure.

Such a local wall section preferably has a wall thickness reduced by at least 40 percent compared to the outer wall surrounding it.

For hollow shafts, which are used in particular in motor vehicle construction, the reduced wall thickness of the local wall section may be in at least one of the following ranges, namely: 0.1 to 2.0 mm, 0.1 to 1.2 mm or 0.1 to 0.8 mm.

With a weakening of the outer wall in the region of the local wall section, the interior remains closed by an integral part of the outer wall with respect to the outside environment. This is particularly advantageous in terms of corrosion protection in hollow shafts made of steel.

In principle, however, as already mentioned, pressure relief can also be achieved via an opening which connects the interior to the outside environment.

For reasons of corrosion protection can be arranged according to a further advantageous embodiment of the invention, a destructible sealing element in this opening, which is destroyed at a defined internal pressure and / or a defined temperature is exceeded, only to release the opening in case of need, but otherwise the interior of the Seal external environment.

Such a sealing element may for example consist of a thermoplastic material. This can be attached to the one with little effort on the opening and on the other hand, simply remove heat to release the opening.

According to a further embodiment of the invention, at least one of the local wall sections lies on a rotation axis of the hollow shaft. As a result, imbalances on the hollow shaft can be avoided. In addition, a sealing element is then not claimed by centrifugal forces.

However, it is also possible to arrange at least one of the local wall sections on the radial outer circumference of the hollow shaft.

It should also be noted that, in particular, a plurality of the abovementioned local wall sections can be provided on a hollow shaft. For example, in addition to an opening which is closed by a sealing element, a local wall thickness weakening may be provided at another location of the hollow shaft. It is also possible to arrange an opening with sealing element at the location of a local wall thickness weakening.

The hollow shaft according to the invention may in particular be part of a motor vehicle drive shaft and be used, for example, as a longitudinal shaft or side shaft in a passenger car or two-wheeled vehicle.

• 1 eine Kraftfahrzeug-Antriebswelle mit einer geschlossenen Hohlwelle nach der Erfindung,
• 2 eine Längsschnittansicht eines ersten Ausführungsbeispiels einer geschlossenen Hohlwelle nach der Erfindung, und in
• 3 eine Längsschnittansicht eines zweiten Ausführungsbeispiels einer geschlossenen Hohlwelle nach der Erfindung.

The invention will be explained in more detail with reference to embodiments shown in the drawing. The drawing shows in:

• 1 a motor vehicle drive shaft with a closed hollow shaft according to the invention,
• 2 a longitudinal sectional view of a first embodiment of a closed hollow shaft according to the invention, and in
• 3 a longitudinal sectional view of a second embodiment of a closed hollow shaft according to the invention.

In 1 is an example of a motor vehicle drive shaft 1 shown, which serves to transmit a drive torque of a non-illustrated drive motor in the vehicle longitudinal direction to a remote from the drive motor axis. The motor vehicle drive shaft 1 has two waves in the present case 2 and 3 on, which by a constant velocity joint 4 connected to each other.

At least one of these waves 2 and 3 is as a closed hollow shaft 10 educated. 2 shows a first embodiment and 3 a second embodiment of this.

Both embodiments have in common that an interior 11 the hollow shaft 10 towards the outside environment is complete. This interior 11 is through an outer wall 12 limited. In the in the 2 and 3 Illustrated embodiments is for this purpose a pipe element 13 axially at its ends by a part 14 of the constant velocity joint 4 as well as by a flange 15 closed. The shape of the tubular element 13 as well as the way of completing the ends of the same through the joint 4 and the flange 15 are merely exemplary in nature and may be practiced otherwise than shown.

The hollow shaft 10 has at least one local wall section 16 on the outside wall 12 on, which at a temperature rise and / or an increase in the pressure in the interior 11 of the hollow shaft 10 opens automatically beyond a certain level.

At the in 2 illustrated first embodiment, the local wall portion 16 opposite to the surrounding outer wall 12 a reduced wall thickness to open at a defined internal pressure.

If, for example, as a result of an increase in the temperature beyond the intended operating range, an increased internal pressure in the inner space 11 occurs, this increased internal pressure can be achieved by providing a relief opening in the outer wall 12 be reduced. The relief opening in this case is achieved by a targeted local perforation of the outer wall 12 in the region of the weakening of the outer wall 12 at the local wall section 16 created while the overall structure of the hollow shaft 10 is otherwise maintained. The provided for the discharge opening local wall section 16 takes only a very small and practically negligible proportion of the total surface of the hollow shaft 10 to complete. 2 shows an example of a local wall section 16 in the form of a punctual reduction in wall thickness, whose total area can be less than 5 cm ² .

Furthermore, this local wall section 16 opposite the surrounding outer wall 12 have a reduced wall thickness of at least 40 percent.

The reduced wall thickness of the local wall section 16 is preferably in the range 0.1 to 2.0 mm, preferably in the range of 0.1 to 1.2 mm and more preferably in the range of 0.1 to 0.8 mm.

Instead of weakening the wall thickness of the outer wall 12 may be provided for the relief opening local wall section 16 also an opening 17 for connecting interior 11 and external environment, in which a destructible sealing element 18 is arranged. This destructible sealing element 18 is configured so that it is destroyed when a defined internal pressure and / or a defined temperature is exceeded, around the opening 17 release. In the normal operating temperature range of a motor vehicle sealed the sealing element 18 the interior 11 the hollow shaft 10 against the outside environment, so that no moisture in the interior 11 can penetrate.

The sealing element 18 may for example consist of a thermoplastic material which disintegrates under the action of high temperatures, for example, melts. In conjunction with the increase in pressure in the interior associated with a rise in temperature 11 becomes the sealing element 18 thus if necessary from the opening 17 expelled, but remains in the proper operating temperature range of a motor vehicle reliably in the opening 17 ,

In 3 For illustration, two local wall sections are shown, each having an opening and a sealing element. A first local wall section 16 with opening 17 and sealing element 18 is here on the radial outer circumference of the hollow shaft 10 arranged. Another local wall section 16 with opening 19 and sealing element 20 lies on the axis of rotation A the hollow shaft 10 , which causes centrifugal forces on the sealing element 20 be avoided. In the present case is this further local wall section 16 on the flange 15 , The cross section of the openings 17 and 19 is not noticeable in the torsional stiffness, as the openings 17 . 19 can be made with a very small cross-section. The cross-sectional area of an opening 17 . 19 may in particular be less than 0.5 cm ² .

Corresponding local wall sections 16 with weakening of the wall thickness or with a through a sealing element 18 . 20 closed opening 17 . 19 can in a modification of the illustrated embodiments also in other places of the interior 11 bounding outer wall 12 the hollow shaft 10 to be ordered. Ideally, a local wall section is sufficient 16 of the type mentioned for providing a discharge opening. However, also several such local wall sections 16 on a hollow shaft 10 be formed. Here, in particular, local wall sections with weakening of the wall thickness and local wall sections with a through a sealing element 18 . 20 closed opening 17 . 19 together on a hollow shaft 10 either spatially spaced from each other or at the same location, be present.

The invention has been explained in more detail above with reference to exemplary embodiments and further modifications. However, individual technical features, which have been explained above in the context of further individual features, can be implemented independently of these and in combination with other individual features, even if this is not expressly described, as long as this is technically possible. The invention is therefore not limited to the exemplary embodiments, but in particular comprises all embodiments defined by the claims.

LIST OF REFERENCE NUMBERS

1

Automotive drive shaft

2

wave

3

wave

4

Constant velocity joint

10

hollow shaft

11

inner space

12

outer wall

13

tube element

14

Part of the constant velocity joint

15

flange

16

local wall section

17

opening

18

sealing element

19

opening

20

sealing element

A

Rotary axis of the hollow shaft

Claims (10)

Closed motor vehicle hollow shaft (10) for torque transmission with an outer wall (12) and an enclosed by this and the external environment sealed interior (11), and at least one local wall portion (16) on the outer wall (12), which at an increase of Pressure in the interior (11) of the hollow shaft (10) opens automatically as a discharge opening. Closed hollow shaft (10) after Claim 1 , characterized in that the local wall section (16) has a reduced wall thickness with respect to the outer wall (12) surrounding it in order to open at a defined internal pressure. Closed hollow shaft (10) after Claim 1 or 2 , characterized in that the local wall portion (16) relative to the surrounding outer wall (12) has a reduced by at least 40 percent wall thickness. Closed hollow shaft (10) after Claim 2 or 3 , characterized in that the reduced wall thickness of the local wall portion (16) is in at least one of the following ranges: 0.1 to 2.0 mm, 0.1 to 1.2 mm or 0.1 to 0.8 mm. Closed hollow shaft (10) according to one of Claims 1 to 4 , characterized in that the local wall section (16) has an opening (17, 19) for connecting the interior space (11) and the outside environment, in which a destructible sealing element (18, 20) is arranged, which is destroyed when a defined internal pressure and / or a defined temperature is exceeded in order to release the opening (17, 19). Closed hollow shaft (10) after Claim 5 , characterized in that the sealing element (18, 20) consists of a thermoplastic material. Closed hollow shaft after one of Claims 1 to 6 , characterized in that at least one local wall portion (16) on a rotational axis (A) of the hollow shaft (10). Closed hollow shaft after one of Claims 1 to 7 , characterized in that at least one local wall portion (16) on the radially outer periphery of the hollow shaft (10) is arranged. Closed hollow shaft (10) according to one of Claims 1 to 8th , which is designed as a motor vehicle drive shaft (1). Closed hollow shaft (10) according to one of Claims 1 to 9 , which is designed as a longitudinal shaft.

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