WO2000005510A1

WO2000005510A1 - Mechanical transmission line

Info

Publication number: WO2000005510A1
Application number: PCT/FR1999/001776
Authority: WO
Inventors: Pierre Guimbretiere
Original assignee: Gkn Automotive Ag
Priority date: 1998-07-24
Filing date: 1999-07-20
Publication date: 2000-02-03
Also published as: FR2781432B1; AU4913899A; FR2781432A1

Abstract

The invention concerns a line (1) for connecting first (100A) and second (100B) shafts, comprising an intermediate shaft (2), a first joint (3A) linking one first end (4A) of the intermediate shaft and the first shaft, a second joint (3B) linking a second end (4B) of the intermediate shaft and the second shaft (100B), a sleeve (5) radially maintaining the intermediate shaft, and first means (31A) for centring one first end (28A) of the sleeve, adjacent to the first joint, such that the sleeve axis is permanently in contact with said first shaft axis. The sleeve (5) extends over the major part of the intermediate shaft (2). The line comprises means (28B) for centring the sleeve second end (28B), such that the sleeve axis is permanently in contact with the axis of the intermediate shaft or of the second shaft, and intermediate means (32) radially pressing the shaft on the sleeve inner wall (32). The invention is applicable to motor vehicles.

Description

"Mechanical transmission line".

The present invention relates to a mechanical transmission line intended to connect a first shaft to a second shaft, of the type comprising an elongated intermediate shaft for torque transmission, a first joint connected to a first end of the intermediate shaft and intended to be connected to the first shaft, a second seal connected to a second end of the intermediate shaft and intended to be connected to said second shaft, a radial retaining sleeve of the intermediate shaft surrounding the latter, and first means for centering a first end of the sleeve, adjacent to the first joint, so that the axis of the sleeve permanently meets the axis of said first shaft. The invention applies in particular to motor vehicles.

Document FR-B-2 721 667 describes the first end of a transmission line of the aforementioned type.

In this line, the first joint is a fixed tripod joint. The intermediate shaft has a reduction in section in the vicinity of this joint and ends in a rod, one end of which carries the ^' tripod of the joint and the other end of which is integral with the tubular central body of the shaft. The radial retaining sleeve surrounds the rod at a distance and its first end comprises fingers for centering this end in the female element of the first seal. The second end of the sleeve is welded to the central body of the intermediate shaft. The fingers of the sheath swivel in the female element of the tripod joint.

Tripod seals, which are perfectly hokinetic, have good power transmission capacity with good efficiency.

However, their use under a breaking angle leads to the appearance of known cyclic radial excitations. under the name of offset phenomenon, in the tripod and in the intermediate shaft which carries the latter. These undesirable excitations are all the more important as the angle of breaking is important. The radial retaining sleeve of the above-mentioned document makes it possible to limit certain undesirable effects of these radial excitations. Indeed, the sheath, which has a great radial rigidity and which is supported by its fingers in the female element of the joint, radially retains the central body of the shaft and limits the transmission of radial excitations to the latter and therefore to d other parts of the vehicle. The rod carrying the tripod, of lower flexural rigidity than the sheath and the central body of the shaft, therefore absorbs practically all these excitations by bending radially.

However, such a structure induces undesirable bearing forces on the female element by means of the tripod rollers, the rod carrying the tripod being relatively short. Furthermore, this structure can also induce clicks of the guide members of the tripod seal on the corresponding tracks.

The invention aims to solve these problems by providing a transmission line with reduced cost and satisfactory mechanical characteristics, in particular with respect to the offset phenomenon.

To this end, the subject of the invention is a mechanical transmission line of the aforementioned type intended to connect a first shaft to a second shaft, of the type comprising an elongated intermediate torque transmission shaft, a first seal connected to a first end of the intermediate shaft and intended to be connected to said first shaft, a second seal connected to a second end of the intermediate shaft and intended to be connected to said second shaft, a radial retaining sleeve of the intermediate shaft surrounding the latter, and first means for centering a first end of the sleeve, adjacent to the first seal, so that the axis of the sleeve permanently meets the axis of said first shaft, characterized in that the sheath extends over most of the length of the intermediate shaft, in that the transmission line comprises means for centering the second end of the sheath so that the the axis of the sleeve permanently meets the axis of the intermediate shaft or the axis of the second shaft, and in that the transmission line further comprises intermediate means for radial support of the intermediate shaft on the inner wall of the sheath which are arranged in the sheath between the two ends of the sheath.

According to particular embodiments, the transmission line can include one or more of the following characteristics, taken alone or in any technically possible combination:

- The intermediate support means are elastic support and damping means housed between the intermediate shaft and the sleeve; the elastic support means comprise at least one elastic ring surrounding the intermediate shaft; the elastic support means comprise several rings enclosing the intermediate shaft and spaced from one another along the latter; - the first joint is sliding;

- The first seal comprises a first male element, integral with the first end of the intermediate shaft and comprising first arms, a first female element, intended to be integral with the first shaft and delimiting for each first arm a pair _of e tracks, and, mounted on each first arm, a mechanical transmission member intended to roll on one of the corresponding tracks, and the means for centering the first end of the sheath comprise first guide fingers which are provided thereon , each between two first arms of the first male element, and which cooperate with the first female element of the first joint;

- the second seal is a sliding seal; the second seal comprises a second male element, integral with said second end of the intermediate shaft and comprising second arms, a second female element, intended to be integral with the second shaft and delimiting for each second arm a pair of tracks, and , mounted on each second arm, a mechanical transmission member intended to roll on one of the corresponding tracks, and the means for centering the second end of the sheath comprise second guide fingers provided on the latter, each between two second arms of the second male element, and which cooperate with the second female element;

the male elements of the first and second seals comprise the same odd number n of arms regularly distributed angularly with respect to the longitudinal axis of the intermediate shaft, and the arms of the first and second male elements are angularly offset by 180 ° / n relative to the longitudinal axis of the intermediate shaft;

- The means for centering the second end of the sheath comprise means for supporting this second end on the intermediate shaft;

1 the intermediate shaft comprises between its ends a section of outer diameter larger than that of said ends; - Said central section is hollow; and - At least part of the retaining sleeve and / or the intermediate shaft is made of composite material.

The invention will be better understood on reading the description which follows, given solely by way of example, and made with reference to the appended drawings, in which:

FIG. 1 is a schematic view in longitudinal section of a mechanical transmission line at rest according to a first embodiment of the invention,

FIG. 2 is a diagrammatic sectional view taken along line II-II of FIG. 1,

FIGS. 3 and 4 are views similar to FIG. 1, respectively illustrating two other embodiments of the invention, and

FIG. 5 is a view similar to FIG. 1, illustrating a variant of the embodiment of FIG. 4. FIGS. 1 and 2 illustrate a longitudinal transmission line 1 of a motor vehicle which essentially comprises:

a first tree 100A and a second tree 100B (shown diagrammatically in phantom with two dashes),

- an elongated intermediate torque transmission shaft 2 of axis X-X,

a first constant velocity tripod joint 3A sliding, connected on the one hand to a first end 4A of the shaft 2, and on the other hand to the first shaft 100A,

a second constant velocity joint with tripod 3B with axial fixity, connected on the one hand to the second end 4B of the shaft 2, and on the other hand to the second shaft 100B, and a sheath 5 for radial retention of the shaft 2, which surrounds the latter at a distance and which extends over practically the entire length of the shaft 2.

The intermediate shaft 2 is of substantially constant circular current section with a diameter of 26 mm in the example shown. Each end 4A, 4B has a grooved region 7A, 7B each bordered by two annular grooves 8A, 8B of axis X-X.

The general structure of the tripod joints 3A and 3B being substantially identical, only that of the joint 3A will be described below. The structure of the joint 3B is deduced therefrom by substituting the suffix B for the suffix A in the references used. In this description, the differences in structure of the seals 3A and 3B will be mentioned if necessary.

The joint 3A essentially comprises:

(1) A male or tripod element 9A, mounted on the end 4A of the shaft 2 and of ternary symmetry with respect to the axis X-X. This tripod 9A comprises a hub 10A and three radial arms 11A spaced angularly by 120 ° and only one of which is visible in FIG. 1. The hub 10A is pierced with a fluted central bore in which the fluted region 8A is introduced, thus joining together the tripod 9A and the shaft 2 in rotation. The axial retention of the tripod 9A relative to the axis 2 is provided, on the one hand, by a circlip 12A engaged in the groove 8A axially external and, on the other hand, by an annular bead 14A.

(2) A female or tulip element 15A of ternary symmetry with respect to an axis coincident with the axis XX in the aligned position of the joint shown. This tulip 15A has a central recess 16A delimited on either side of each arm 11A by two rolling tracks 17A facing each other. This recess 16A is also delimited between the arms 11A by three walls 18A for supporting the sheath 5 which each connect a track 17A corresponding to an arm 11A to another track 17A corresponding to another arm 11A. The walls 18A of the joint 3A belong to a cylinder coaxial with the tulip 15A and the walls 18B of the joint 3B belong to a sphere centered on the axis of the tulip 15B. The shaft 100A is connected to the tulip 15A via a flange 19A.

(3) For each arm 11A, a roller 20A of revolution which is mounted to pivot and slide on the arm 11A by means of a needle bearing. This member 20A is intended to roll on one or the other of the corresponding tracks 17A opposite.

The arms 11A of the first seal 3A and the arms 11B of the second seal 3B are angularly offset by 60 ° relative to each other.

The sheath 5 is a tubular element of ternary symmetry with an axis X'-X 'coinciding with the axis X-X of the shaft 2 in the rest position of the line 1 shown in FIGS. 1 and 2.

This sheath 5 comprises a central main part 22 tubular and of revolution about the axis X'-X ', extended on either side by a first end part 23A and a second end part 23B. The central part 22, in the example shown, has an outside diameter of approximately 75 mm and a thickness of approximately 2.5 mm. The end parts 23A and 23B are short axial lengths relative to the main part 22. The end parts 23A and 23B are each welded to one of the edges 24A, 24B of the central part 22.

Each end part 23A successively has from section 24A, 24B a section 26A, 26B of the same diameter as the central part 22, a converging section 27A, 27B, and an externally spherical opening 28A, 28B constituting one end of the sleeve 5. Each opening 28A, 28B has three longitudinal cuts 30A, 30B which delimit between them three centering and guide fingers 31A, 31B which are offset angularly 120 ° with respect to the longitudinal axis X'-X 'of the sleeve 5.

The notches 30A and 30B constitute clearances in which the arms 11A and 11B are respectively housed. The outer surface of each finger 31A, 31B is supported on a wall 18A, 18B of the tulip 15A, 15B.

Line 1 further comprises means 32 for supporting the shaft 2 against the sheath 5 in the form of two elastic rings 33 made of elastomer and housed with compression preload between the sheath 5 and the shaft 2. These rings 33, of axis XX in the position shown, are spaced from each other along the axis XX and are arranged substantially symmetrically with respect to the middle of the shaft 2. These rings 33 surround the shaft 2 and extend radially up to the sheath 5.

In the example shown, the length of the shaft 2 is approximately 800 mm and the rings 33 are arranged 300 mm from the ends 3A and 3B.

For each end portion 23A, 23B of the sleeve 5, an annular ring 34A, 34B for sealing is disposed between the converging section 27A, 27B and the shaft 2. For each tripod joint 3A, 3B, a bellows sealing 35A, 35B extends between the tulip 15A, 15B and the converging section 27A, 27B of the sleeve 5.

The transmission line 1 makes it possible to transmit a torque between the tulips 15A and 15B and therefore between the first shaft 100A and the second shaft 100B, by through the intermediate shaft 2 and the tripods 9A and 9B which are supported by the rollers 20A and 20B on the tracks 17A and 17B of the tulips 15A and 15B.

The joint 3A is a sliding joint, the tripod 9A and the end 28A of the sheath 5 being able to slide relative to the tulip 15A along the axis of the latter due to the shapes of the radially outer surface of the end 28A sheath 5 and walls 18A. The joint 3B is an axial fixity joint obtained in particular by virtue of the combined spherical shape of the walls 18B of the tulip 15B and of the radially outer surface of the opening 28B.

Furthermore, in the transmission line described, the intermediate shaft 2 is sufficiently resistant to torsion to fully transmit the torque, but its flexural rigidity is relatively low compared to that of the sleeve 5 and in particular insufficient for it to be able to rotate. only at the speed required by the use, for example 5000 rpm. The critical speed of rotation (speed from which a buckling and a rupture is observed) of the sleeve 5 and shaft 2 assembly is, due to the structure of the line 1, relatively high and notably higher than that of the tree 2.

Indeed, the ends 28A and 28B of the sheath 5 are centered in the tulips 15A and 15B, thanks to the centering fingers 31A and 31B. The X-X axis therefore permanently meets the axes of the shafts 100A and 100B. The radial position of the sleeve is thus fixed. The elastic rings 33 limit the radial displacements of the shaft 2 with respect to the sheath 5 and therefore oppose its buckling and its breaking.

When, for example, only the joint 3A operates at a breaking angle, the tripod 9A is subject to offset phenomenon. Periodic radial excitations are therefore transmitted to the intermediate shaft 2 by its first end 4A, these excitations tending to move the shaft 2 radially with respect to the axis X'-X 'of the sleeve 5.

These radial displacements of the shaft 2 are damped and limited by the elastic rings 33 on which it is supported.

This damping makes it possible to limit the undesirable effects, such as vibrations, due to the offset phenomenon, by also limiting the reaction forces of the rollers 20A on the tulip 15A, in particular compared to those appearing in the device in the state of the technique presented at the beginning of the description. The operation of the transmission line 1 when only the joint 3B operates under a breaking angle is similar to that described above.

When the two seals 3A and 3B operate simultaneously at a breaking angle, the two ends 4A and 4B of the intermediate shaft 2 receive radial excitations from the tripods 9A and 9B. The role of the sheath 5 and the rings 33 is identical to that described above. It should be noted however that, due to the angular offset of the arms 11A and 11B of the tripods 9A and 9B, the effects of the offset phenomena appearing in the two seals are opposed and can, if the seals 3A and 3B operate under the same breaking angle, combine advantageously. This characteristic makes it possible to further limit the effects due to offset phenomena. The transmission line 1, relatively simple and inexpensive, makes it possible, with the dimensions indicated, to transmit torques of the order of 40 daNm continuously and maximum torques of around 250 daNm. The rotation speeds can be of the order of 5000 rpm. Maximum break angles can be around 20 degrees. The critical speed of rotation of the shaft 2 and sleeve 5 assembly is approximately 7000 rpm.

FIG. 3 simultaneously illustrates several variants of a second embodiment of the invention which differs from the first embodiment described by the following.

In this FIG. 3, the relative axial length of the intermediate shaft 2 with respect to that of the other parts has been reduced for greater clarity. The seal 3B is a sliding tripod seal and the seals 3A and 3B, of identical structure, each include a stop 350A, 350B housed in the recess 16A, 16B of the tulip 15A, 15B to limit the axial movement of the shaft 2. Each tripod 9A, 9B is fixed in translation relative to the shaft 2 by two circlips 12A, 12B each engaged in a groove 8A, 8B.

The shaft 2 comprises a hollow central sleeve 36 and two end bars 37A and 37B.

Each bar 37A, 37B has one end 38A, 38B housed in one end 39A, 39B of the sleeve 36. The other end of each bar 37A, 37B forms the end 4A, 4B of the shaft 2. Bars 37A and 37B are integral in rotation with the sleeve 36. This joining can be ensured by welding as shown for the bar 37A in Figure 3 or, as shown for the bar 37B, by means of grooves formed at the ends 38B and 39B.

The sheath 5 comprises two halves 41A and 41B of generally frustoconical shapes each converging towards the end 28A, 28B of the corresponding sheath 5. These halves 41A and 41B are connected by a central annular weld bead 42. Each half 41A, 41B ends in an externally spherical expansion 28A, 28B as described in the embodiment of FIGS. 1 and 2. The means 32 for supporting the intermediate shaft 2 on the sheath 5 comprise a single annular elastomer ring 33, which bears internally on the sleeve 36 and which is surrounded externally by a metal ring 45. This metal ring 45 takes it -same support, in the vicinity of the cord 42, on the halves 41A and 41B in which it is force fitted.

The upper and lower half-views illustrate two distinct variants of the second embodiment of the transmission line 1.

In the variant of the upper half-view, the rings 33 and 45 are of substantially rectangular section. In the variant of the lower half-view, the ring 33 has an annular central groove 46 radially outside in which is housed an annular rib 47 radially inside of the ring 45. The radial thickness of the ring 33 is smaller in this variant than in the variant of the upper half-view.

The operation of this second embodiment is substantially similar to that of the first embodiment described above. It should be noted that the structure of the intermediate shaft 2, and in particular the presence of the hollow central sleeve 36, gives it greater torsional rigidity than that of the embodiment of FIG. 1.

The freedom of radial movement of the shaft 2 authorized by the variant of the lower half-view is less than that authorized by the variant of the upper half-view. Thus, this variant is particularly suitable for the case where the seals 3A and 3B operate at the same breaking angle, the radial displacements of the shaft 2 at the level of this ring 33 being minimal in this case.

The rib 47 ensures the axial centering of the ring 33 relative to the shaft 2. The metal ring 45 facilitates the assembly of the two halves 41A and 41B.

FIG. 4 illustrates a third embodiment which differs from that of FIG. 1 by the nature of the seals 3A and 3B, and by the structure of the end portion 23B of the sleeve 5. The walls 18A of the seal 3A belong to a sphere centered on the axis of the tulip 15A and the joint 3A is a joint with axial fixity.

The seal 3B is a conventional sliding ball joint which essentially comprises an inner nut 50 secured to the end 4B of the drive shaft 2, an outer bell 51 secured to the second shaft 100B, six balls 52 regularly distributed angularly around the 'axis XX of the shaft 2, and a cage 53 for holding the balls 52. Such a joint 3B is constant velocity, sliding, can work under a breaking angle, but is not subject to the phenomenon of offset.

The sheath 5 extends from one end 4A of the shaft 2 substantially over most of the length of the latter. The end portion 23B of the sleeve 5 is of revolution of axis X'-X 'with a sigmoidal section. This part 23B is fixed inside the central part 22 of the sleeve 5 at the edge 24B of the latter, for example by means of screws or rivets. The internal end 28B of the part 23B is substantially annular with an axis XX and bears on an annular region 57 of the intermediate shaft 2 located near the end 4B. Thus, this end 28B, and therefore the slice 24B, are centered on the axis XX of the shaft 2, the slice 24B being kept away from the shaft 2. The axis X'-X 'of the sleeve 5 therefore permanently meets the axis XX of the intermediate shaft 2.

An annular seal 58 engaged in a groove 59, annular with axis XX and arranged axially on the side of the end 4B relative to the region 57, bears on the axially external surface 60 of the end part 23B of the sleeve 5. This seal 58 thus ensures axial retention of the sleeve 5 by limiting its movements towards the end 4B. The movements of the sheath 5 towards the end 4A are limited due to the swiveling connection between the end 28A of the panel 5 and the tulip 15A. The axial displacements of the shaft 2 towards the shaft 100A are limited by a sheet 60A for closing the seal 3A on which the end 4A of the shaft 2 comes to bear.

The operation of this third embodiment is analogous to that described for the first embodiment of the invention.

FIG. 5 illustrates a variant of the transmission line 1 of FIG. 4, in which the intermediate shaft 2 has, over a large part of its length, a hollow central section 61 with an outside diameter clearly greater than that of the ends 4A and 4B of the shaft 2. The support means 32 comprise a single elastic ring 33 enclosing the shaft 2 on the side of the end 4A with respect to a transition section 62 connecting this end 4A to the hollow central section 61. This ring 33 is also supported on the section 26A of the end portion 23A of the sleeve 5. This variant makes it possible, like the embodiment of FIG. 3, to increase the torsional stiffness of the shaft 2.

More generally, the invention relates to transmission lines equipped with two seals, at least one of which is capable of generating in operation radial excitations. Also more generally, the invention relates to transmission lines equipped with two seals in which the elongated intermediate shaft is capable of generating in operation radial excitations.

In the case where the transmission line comprises two seals provided with male elements comprising the same number of arms n regularly angularly offset, the arms of each of the seals are preferably angularly offset respectively by 180 ° / n so that the radial excitations appearing in the two joints tend to oppose.

The materials used to make the sheath 5 and / or the shaft 2, in particular the central section 61 of FIG. 5, can be metals or composite materials.

Claims

KEVEtroiCATIOWS

1. Mechanical transmission line (1) intended to connect a first shaft (100A) to a second shaft (100B) of the type comprising an elongated intermediate shaft

_> (2) torque transmission, a first anointed (3A) connected to a first end (4A) of the intermediate shaft (2) and intended to be connected to said first shaft (100A), a second seal (3B) connected to a second end (4B) of the intermediate shaft and intended to be

10 connected to said second shaft (100B), a sleeve (5) for radial retention of the intermediate shaft (2) surrounding the latter, and first means (31A) for centering a first end (28A) of the sleeve, adjacent at the first joint (3A), so that the axis (X'-X ') of the sheath li permanently meets the axis of said first shaft (100A), characterized in that the sheath (5) extends over the essential of the length of the intermediate shaft (2), in that the transmission line comprises means (28B) for centering the second

End of the sleeve (5) so that the axis (X'-X ') of the sleeve permanently meets the axis (XX) of the intermediate shaft (2) or the axis of the second shaft (100B), and in that the transmission line further comprises intermediate means (32) for radial support of the intermediate U shaft (2) on the inner wall of the sheath which are arranged in the sheath between the two ends (28A, 2ΘB ) of the scabbard.

2. Line according to claim 1, characterized in that the sheath (5) for radial retention surrounds the shaft

30 intermediate (2) remote.

3. Line according to claim 1 or 2, characterized in that the intermediate means (32) of support are elastic means (32) of support and

RECTIFIED SHEET (RULE 91) ISA / EP damping housed between the intermediate shaft (2) and the sleeve (5).

4. Line according to any one of claims 1 to 3, characterized in that the elastic support means comprise at least one elastic ring (33) surrounding the intermediate shaft (2).

5. Line according to claim 4, characterized in that the elastic support means comprise several rings (33) enclosing the intermediate shaft (2) and spaced from one another along the latter.

6. Line according to any one of claims 1 to 5, characterized in that the first seal (3A) is sliding.

7. Line according to any one of claims 1 to 6, characterized in that the first seal (3A) comprises a first male element (9A), integral with the first end (4A) of the intermediate shaft (2) and comprising first arms (11A), a first female element (15A), intended to be integral with the first shaft (100A) and delimiting for each first arm a pair of tracks (14A), and, mounted on each first arm (11A) , a mechanical transmission member (20A) intended to roll on one of the corresponding tracks, and in that the means for centering the first end (28A) of the sleeve (5) comprise first guide fingers (31A) which are provided on the latter, each between two first arms of the first male element (9A), and which cooperate with the first female element (15A) of the first seal (3A).

8. Line according to any one of claims 1 to 7, characterized in that the second seal (3B) is a sliding seal.

9. Line according to any one of claims 1 to 8, characterized in that the second seal comprises a second male element (9B), integral with said second end (4B) of the intermediate shaft (2) and comprising second arms (11B), a second female element (15B), intended to be integral with the second shaft (100B) and delimiting for each second arm a pair of tracks (17B), and, mounted on each second arm (11B), a mechanical transmission member (20B) intended to roll on one of the corresponding tracks, and in that the means for centering the second end (28B) of the sleeve ( 5) comprise second guide fingers (31B) provided on the latter, each between two second arms (11B) of the second male element (9B), and which cooperate with the second female element (15B).

10. Line according to claim 8 or 9, characterized in that the male elements (9A, 9B) of the first and second seals comprise the same odd number n of arms (11A, 11B) regularly distributed angularly with respect to the longitudinal axis (XX) of the intermediate shaft (2), and in that the arms (11A, 11B) of the first and second male elements (9A, 9B) are angularly offset by 180 ° / n relative to the longitudinal axis ( XX) of the intermediate shaft (2).

11. Line according to any one of claims 1 to 8, characterized in that the means for centering the second end (28B) of the sleeve (5) comprise means (28B) for supporting this second end on the intermediate shaft (2).

12. Line according to any one of claims 1 to 9, characterized in that the intermediate shaft comprises between its ends (4A, 4B) a section (36; 61) of outer diameter larger than that of said ends (4A, 4B).

13. Line according to claim 12, characterized in that said central section (36; 61) is hollow.

14. Line according to any one of claims 1 to 13, characterized in that at least part of the retaining sleeve (5) and / or the intermediate shaft (2) is made of composite material.