DE9100377U1 - Shaft, in particular variable length cardan shaft, with a deformable torque overload indicator - Google Patents

Description

GKN Cardantec International 10. Jan. 199j

Company for Drive Technology mbH Hw/Tu (1233A)

Westendhof 7-9 90.133 DE 0 4300 Essen 1

Shaft, especially variable length cardan shaft,
with a deformable torque overload indicator

Description

The invention relates to a shaft, in particular a length-variable universal joint shaft, with a torsion-free holding means running coaxially thereto, one end of which is connected to the shaft in a rotationally fixed manner and the other end and the shaft opposite it are provided with interacting display means for displaying a rotation of the shaft under torque.

Such a shaft, for example a variable-length cardan shaft as known from DE 36 36 167 C2, is used, for example, to transmit torque in the drive train of motor vehicles.

Such cardan shafts are a safety component, particularly in commercial vehicles, as they must transmit not only the drive but also braking forces to the wheels when the engine brake is activated. To avoid or detect torque overloads, the known cardan shaft is provided with a display that shows plastic deformation caused by overload. However, overloads can also be in the area of elastic deformation, which cannot be detected with the known display.

The object of the invention is to create a display with which elastic and plastic deformations of a shaft of the type described above caused by torque overloads can be made permanently recognizable.

This object is achieved in that the display means associated with the holding means and the shaft consist, on the one hand, of a radially directed bolt and, on the other hand, of deformation elements arranged in the circumferential direction on both sides of the bolt and covered by a cover having transparent areas at both ends, which, when subjected to the bolt in the transparent area of the cover resulting from torque overloads on the shaft, are permanently deformed.

These measures create a display option that, regardless of the type of deformation, provides a permanent indication of twists that exceed a certain tolerance range between two distant measuring points on a shaft. The harmless tolerance range can be varied depending on the design of the shaft.

In an advantageous embodiment of the invention, it is provided that the deformation elements have material weakenings for their permanent deformation.

In order to ensure a permanent display that cannot be manipulated, it is intended that the deformation elements in the material weakenings are permanently bent out of their orientation.

To increase the deformation path by means of a translation it is intended that the deformation elements

run radially and are held at one end by the material weakenings and are exposed at the opposite free end, and the contact areas between the bolt and the deformation elements are located between the material weakenings and the free ends.

To improve visibility, it is intended that the free ends of the deformation elements are provided with signal surfaces that tilt into the transparent areas of the cover. To simplify handling of the cover covering the deformation elements, it is intended that the cover and the transparent areas assigned to it on both sides in the circumferential direction are connected to one another in one piece.

Preferably, the deformation elements with the panel provided with transparent areas form a pre-assembled display unit which is connected to the holding means.

Various designs of the holding means are possible. Therefore, for a first embodiment, it is proposed that an outer tube running radially outwardly coaxially to the shaft is provided as the holding means and that the deformation elements are assigned to the outer tube.

Alternatively, the holding means may also be an indicator shaft arranged longitudinally in one or both of the hollow shaft parts.

If it is designed as an overtube, two arrangement variants are also provided. According to a first design variant, the overtube is fixed to a shaft part by a connection at one end and is guided, with the shaft pushed in, to the area of the free end of the other shaft part, bridging the length compensation. The display means are attached to this free end of the other shaft part and to that of the overtube.

In such an embodiment, the position of the free end of the overtube changes relative to the shaft part containing the additional display means in accordance with the change in length of the shaft. For this reason, it is proposed in a further embodiment to adapt the deformation elements to the displacement range of the length compensation. This also makes it possible to adapt the tolerance field to the permissible torsional movements in the individual length positions. In the extended position, a greater deformation occurs at the same torque than in the retracted position. Therefore, the larger measurement deflections are still within the permissible range.

Alternatively, it is possible to fix the cover tube at one end to a shaft part, for example in the area of the length compensation, using a connection and to attach the indicators to the other end and to the area of the same shaft part opposite it. In this case, there is no change in the positioning of the indicators relative to one another when the length of the shaft changes.

Preferably, the indicator means are arranged in the radial gap between the outer tube and the shaft part. It is easily possible to adjust the position of the indicator means

parts to be swapped. For example, the bolt can be assigned either to the free end of the cover tube pointing radially inwards or to the outer surface of the shaft part pointing radially outwards. The deformation elements are assigned to the other part, cover tube or shaft part. In the event that an indicator shaft arranged coaxially in the hollow interior of the shaft is provided, this is connected to a shaft part in a rotationally fixed manner at the greatest possible distance from its free end, which carries one of the interacting indicator means. If an indicator shaft is provided for the display, the indicator means assigned to it can be arranged together with the indicator means cooperating with it in an axial opening in the free end of a shaft part. The arrangement is preferably provided in the area of a central opening in the joint fork if a joint shaft is affected, otherwise in the end face of the shaft. In such a case, the deformation elements are to be arranged eccentrically to the axis of rotation of the shaft.

Alternatively, it is also possible to allow the indicator means assigned to the indicator shaft in the form of a bolt to protrude radially into an opening in a shaft part and to assign the connecting elements to this.

In connection with the arrangement of a display shaft centrally to the shaft parts, which are axially displaceable relative to one another, it is proposed in a further embodiment of the invention that the display shaft is guided so as to be axially displaceable relative to the shaft part to which it is attached in a rotationally fixed manner, or relative to the axially fixed display means, which is assigned to the display shaft.

In order to enable axial adjustment, the radially extending bolt in the opening is guided so that it can only move in the circumferential direction of the associated shaft part. This fixes the display shaft in the axial direction relative to the display means. The radially outward arrangement of the display means towards the outer circumference of one of the shaft parts or components connected to it also causes the display to be enlarged.

Finally, in a further embodiment, it is provided that the display shaft is guided in a support between the connection on the shaft part and the bolt assigned to it.

The advantage of this arrangement is that at high speeds the indicator shaft is securely supported.

The invention is illustrated by means of various embodiments in the accompanying drawings and is described in more detail below.

It shows

Figure 1 shows the longitudinal view, partially in section, of a variable length universal joint shaft with an overtube covering the length compensation between the first shaft part and the second shaft part;

Figure 2 shows the longitudinal view of a variable length universal joint shaft, partially sectioned, with an overtube spanning only the second shaft part;

Figure 3a shows the detailed representation corresponding to detail "Z" in Figures 1 and 2, with deformation elements deformable in the plane of the shaft, in longitudinal view,

Figure 3b shows the axial view of the detail "Z" according to Figure 3a,

Figure 3c shows the top view of the view "Z" according to Figures 3a and 3b, shown without a cover,

Figure 4a shows the detailed representation corresponding to detail "Z" in Figures 1 and 2, with deformable deformation elements running perpendicular to the plane of the shaft in a longitudinal view,

Figure 4b shows the section along the line A-B in Figure 4a,

Figure 5

the longitudinal view of a variable length cardan shaft with an indicator shaft running axially centrally in the second cardan shaft part,

Figure 6

the longitudinal view of a variable length universal joint shaft with an indicator shaft running axially centrally in the first and second shaft parts,

Figure 7a shows the detailed view according to the section along the line C-D in Figure 5,

Figure 7b the section along the line E-F in Figure 7a,

Figure 8a shows the detailed view of the detail "Y" in Figure 6,

Figure 8b shows the axial view of the detail "Y" according to Figure 8a,

Figure 8c shows the top view of the detail "Y" according to Figures 8a and 8b, shown without aperture .

The universal joint shaft 10 shown in Figures 1, 2, 5 and 6 consists essentially of a first shaft part 11 and a second shaft part 12, which are connected to one another via a length compensation device that can be moved axially into one another. For length compensation, the first shaft part 11 is provided with a radially inner profiled pin 13, which is slidably received in a sleeve 14 that is also profiled and is assigned to the second shaft part 12. The shaft parts 11 and 12 are provided at the ends with joint forks 15 and 15a, respectively, which in turn are connected in an articulated manner via joint crosses to further joint forks provided with connecting flanges 16.

As shown in Figure 1, an overtube 18 is arranged at the connection point 17, which coaxially spans the first shaft part 11 and partially the second shaft part 12 radially on the outside. In the embodiment shown, when the shaft 10 is pushed in, the overtube 18 extends from the connection 17 in the area of the joint fork 15 of the first shaft part 11 to the area of the joint fork 15a of the second shaft part 12. In order to achieve a uniform spacing from the outer surface 35 of the second shaft part 12, the free end of the overtube 18 is provided with an overtube bearing 20 in the form of a seal and is held at a uniform distance to form an annular gap 37.

The overtube 18, together with the seal 20, simultaneously serves to seal the shaft parts 11 and 12 against each other when their length changes. In the embodiment shown in Figure 2, the overtube 18 is secured with a connection 17a to the second shaft part 12 in the area of the parts that form the length compensation, pin 13 and sleeve 14. The overtube 18 extends with its free end into the area of the joint fork 15a of the second shaft part 12 and remains in this position, since there is no change in length between the overtube 18 and the second shaft part 12 when the length of the shaft changes. The length compensation 13, 14 is not covered by the overtube 18 and is sealed by another protective tube.

In both cases, in the area of the free end of the overtube 18 and the opposite second shaft part 12, there are indicators 19, which are shown in detail in Figures 3a, 3b, 3c, 4a and 4b. When torque is applied to the universal joint shaft 10, the ends, which are shown by the flanges 16, rotate relative to one another by a maximum deflection, while the areas in between rotate to a correspondingly lesser extent.' Since the holding means designed as an overtube 18 does not participate in the torsion, i.e. is torsion-free, the position of any point at its free end changes relative to the opposite shaft part 12 in the circumferential direction. The rotation can be in the area of elastic or plastic deformation of the shaft 10 or the shaft parts 11 and 12. In the elastic range, the material returns to its original position after the load is removed, whereas in the case of plastic deformation, the torsion remains even after the load is removed.

Undesirable load conditions can also occur in the area of elastic deformation, but these are usually no longer recognizable after the load is removed.

The embodiments of the invention described below allow a permanent display of any deformations that have exceeded a certain tolerance range, i.e. also those that lie within the elastic deformation range of a shaft 10 equipped in this way.

In the embodiment shown in Figures 3a, 3b and 3c, a display unit 19 is provided in the area of the free end of the overtube 18. As Figure 3a shows, the display unit 19 consists of a bolt 22 assigned to the shaft part 12, which is held in a bolt holder 26, for example in the form of a plate welded to the shaft part 12. This bolt 22 extends, as shown in Figures 3b and 3c in particular, into the area of the deformation elements 24 assigned to the overtube 18, which are held in position by means of material weakenings 25. On both sides of the bolt 22, free spaces 29 forming tolerance ranges are provided opposite the deformation elements 24. The deformation elements 24 run parallel to the longitudinal axis of the overtube 18 and are covered radially on the outside with a cover 21.

On their outer sides facing away from the bolt 22, the deformation elements 24 are exposed with free spaces 28. These free spaces 28 are located, as Figure 3b shows, in transparent areas 23 of the panel 21. These transparent areas or windows 23 can be connected in one piece to the panel 21 and consist of the same material as the latter.

In the event of torque overloads, the deformation elements 24 are bent by the bolt 22 into the free spaces 28, where, as shown in Figure 3c, they become visible in the deformed state 27. The display unit 19 can be attached to the free end of the overtube 18 or integrated into it. A reverse assignment on the shaft 12 is also possible. To make the deformation elements 24 easier to recognize, they can be marked in color. The

The clearances 29 provided between the bolt 22 and the deformation elements 24 are intended to ensure that deformation only occurs when the shaft 10 or the shaft parts 11 and 12 are overloaded with torque. To increase the reading accuracy, the aperture 21 can be arranged radially on the outside, close to the deformation elements 24.

To increase the deformation paths in the event of torque overloads, a transmission can be provided, as shown in Figures 4a and 4b. In this design, the deformation elements 24a are integrally formed on the ends of an opaque cover 21a in the circumferential direction. This cover 21a can be integrated into an otherwise transparent window 23. The formation takes place via material weakenings 25a that act as pivot points. The deformation elements 24, which run perpendicular to the pipe plane of the over-pipe 18, have signal surfaces 30 on their radially inner free ends 30a. The bolt 22 connected to the shaft 12 is provided radially on the outside with a bolt head 31, which can be brought into contact with contact areas 36 provided approximately centrally on the deformation elements 24 in the event of torque overloads. This arrangement means that even with small twisting distances, the deformation element 24a that is being pushed is moved out of position in its material weakening 25a and the signal surface 30 is tilted into the transparent area 23 of the cover 21. The pivot point or the line around which the deformation element 24a is tilted can be determined very precisely by suitable material weakenings 25a. As a result, even when deformation begins, i.e. when a limit torque of the shaft 10 or shaft parts 11 and 12 is reached, only a very small additional twist is necessary to achieve full deflection of the deformation element 24a.

By appropriately designing and dimensioning the deformation elements 24 and 24a or the bolt 22, it can be ensured that even with large deformation paths no destruction, i.e. no breaking, occurs. If the limit moment is significantly exceeded, the bolt 22 tilts the deformation elements 24 or 24a so far outwards that it can move freely underneath them. The signal surfaces 30 remain visible even with repeated overloading.

In the embodiment shown in Figure 5, a centrally axially extending indicator shaft 32 is provided in the hollow second shaft part 12 as a holding means. At least one radially inward-pointing support 33 is provided to support the indicator shaft 32 at high speeds of the universal joint shaft 10. The indicator shaft 32 is also torsion-free, so that twisting of the universal joint shaft 10 or its shaft parts 11 and/or 12 relative to it can be determined. The indicator shaft 32 is attached at one end to the second shaft part 12 in a rotationally fixed manner with a connection 17b. At the opposite free end, the indicator shaft 32 is coupled to an indicator unit 34, which includes the indicator means 19. These are designed according to the operating principles described above according to Figures 3a, 3b, 3c, 4a and 4b and are inserted into the universal joint fork 15a. The display means 19 are described in detail with reference to Figures 7a and 7b.

In the shaft design shown in Figure 6, the centrally axially extending indicator shaft 32 is mounted in the first shaft part 11 in a rotationally fixed manner, whereby a larger indicator deflection is achieved with the same moment load on the universal joint shaft due to the larger twisting length. The necessary for length compensation

Axial relative movement can be provided, for example, by a square guide 17c between the display shaft 32 and the shaft part 11 or by a corresponding connection between the display shaft 32 and the display unit 34. To increase the critical speed of the display shaft 32, at least one radially inward-pointing support 33 is provided.

In addition, Figure 6 shows a design for the display in which the bolt 22 is guided through a circumferential opening 39 in the joint fork 15a to the circumference of the free shaft end. This measure also enlarges the display. The design of the display is shown in detail in Figures 8a, 8b and 8c.

Figures 7a and 7b show a possible design of the display unit 34, as used for the design of the holding means in Figure 5. As in the design shown in Figures 4a and 4b, the deformation elements 24b are tilted about an axis of rotation that is precisely defined by material weakenings 25b, but which is axially aligned. As a result, the signal surfaces 30b are located at the ends of the deformation elements 24b, as are the transparent window 23 and the cover 21 in the plane of the inner surface 38 of the joint fork 15a. In the event of torque overloads, the bolt head 31 of the bolt 22 touches the deformation elements 24b in contact areas 36 that are close to the axis of rotation of the same. As a result, when the limit torque is reached, even a small additional twist of the joint shaft causes a large deflection of the display.

Figures 8a, 8b and 8c show a further embodiment of the display means 19 in combination with a centrally axially extending display shaft 32 as a holding means. The bolt 22, which is firmly connected to the display shaft 32, is guided to the circumference of the universal joint shaft or the universal joint fork through an opening 29 in the yoke 15a, which is designed as a circumferential slot. The opening via the bolt 22 fixes the display shaft 32 in the axial direction on the one hand and on the other hand enables the bolt 22 to move freely in the circumferential direction and thus a rotation of the display shaft 32 relative to the shaft part 12. The deformation element 24 can, as shown, be designed in accordance with Figure 3c and is attached directly to the yoke 15a together with the window 23 and the cover 21.

GKN Cardantec International 20 Jan 1991

Company for Drive Technology mbH Rw/Tu (1233A)

Westendhof 7-9 90.133 DE 0 4300 Essen 1

Shaft, especially variable length cardan shaft,
with a deformable torque overload indicator

List of reference symbols

10 Cardan shaft 11 first wave part 12 second shaft part 13 profiled tenon 14 profiled sleeve 15,15a Articulated fork 16 Connection flange 17,17a, 17b,17c Connection 18 Overtube 19,19a Display unit 20 Overpipe sealing 21 cover 21a integrated aperture 22 'Bolt 23 Window 23a transparent area 24,24a, 24b Deformation element 25,25a, 25b Material weakening 26 Bolt holder 27 deformed deformation element 28 free space 29 free space 30 Signal area 30a,30b free end 31 Bolt head 32 Display shaft 33 Support

34 Advertisement 35 surface 36 Contact area 37 gap 38 Inner surface of the joint fork 39 breakthrough

Claims (17)

GKN Cardantec International 10 Jan 1991 Company for Drive Technology mbH Hw/Tu (1233A) Westendhof 7-9 90.133 DE 0 Essen 1 Shaft, especially variable length cardan shaft,
with a deformable torque overload indicator Protection claims 1. Shaft, in particular a variable-length cardan shaft, with a coaxial, torsion-free holding means, one end of which is connected to the shaft in a rotationally fixed manner and the other end and the shaft opposite it are provided with interacting display means for displaying a rotation of the shaft under torque, characterized, that the display means associated with the holding means (18, 32) and the shaft (10, 11, 12) consist, on the one hand, of a radially directed bolt (22) and, on the other hand, of deformation elements (24, 24a) arranged in the circumferential direction on both sides of the bolt (22) and covered by a cover (21) having transparent areas at both ends, which, when subjected to the bolt (22) as a result of torque overloads on the shaft (10, 11, 12), lie in the transparent area (23) of the cover (21), permanently deformed. 2. Shaft according to claim 1,
characterized, that the deformation elements (24,24a,24b) have material weakenings (25,25a,
25b). 3. Shaft according to claim 2,
characterized, that the material weakenings (25) of the deformation elements (24) are designed to run radially to the axis of rotation of the shaft (12). 4. Shaft according to claim 2,
characterized, that the material weakenings (25a,25) of the deformation elements (24a,24b) are designed to run parallel to the axis of rotation of the shaft (12). 5. Shaft according to claims 1 to 4,
characterized, that the deformation elements (24,24a,24b) in the material weakenings (25,25a,25b) are permanently bendable from their orientation. 6. Shaft according to claims 1 to 5,
characterized, that the deformation elements (24a, 24b) run radially and are held at one end by the material weakenings (25a, 25b) and are exposed at the opposite free end (30a, 30b), and the contact areas (36) between the bolt (22) and the deformation elements (24a, 24b) lie between the material weakenings (25a, 25b) and the free ends (30a, 30b). 7. Shaft according to one or more of claims 1 to 6,
characterized, that the free ends (30a, 30b) of the deformation elements (24a, 24b) are provided with signal surfaces (30) which tilt into the transparent areas (23) of the diaphragm (21). 8. Shaft according to one or more of claims 1 to 7,
characterized, that the cover (21) and the transparent areas (23) assigned to both ends in the circumferential direction are connected to one another in one piece. 9. Shaft according to one or more of claims 1 to 8,
characterized, that the deformation elements (24,24a, 24b) with the panel (21y 21a) provided with transparent areas (23,23a) form a pre-assembled display unit (19) which is connected to the holding means (18,32). 10. Shaft according to claim 1,
characterized, that an outer tube (18) running coaxially radially outward to the shaft (10; 11, 12) is provided as the holding means and the deformation elements (24, 24a, 24b) are assigned to the outer tube (18). 11. Shaft according to one or more of claims 1 to 10, characterized in that the holding means is a display shaft (32) which is arranged longitudinally of one or both of the hollow shaft parts (11, 12). 12. Shaft according to claim 11,
characterized, that the display shaft (32) is connected in a rotationally fixed manner to a shaft part (11 or 12) at the greatest possible distance from its free end, which carries one of the cooperating display means (19, 19a). 13. Shaft according to claim 11 or 12,
characterized, that the display means cooperating with the display means associated with the display shaft (32) is arranged in an axial opening in the free end (articulated fork 15a) of a shaft part (12). 14. Shaft according to claim 11,
characterized, that the display means (22,39) assigned to the display shaft (32) is designed as a bolt (22) and projects radially into an opening (39) of a shaft part (12,15a) and the deformation elements (21,24) are assigned to this. 15. Shaft according to claim 11,
characterized, that the display shaft (32) is guided axially relative to the shaft part (H) to which it is attached in a rotationally fixed manner, or relative to the axially fixed display means that is assigned to the display shaft (32). 16. Shaft according to claims 14 and 15, characterized in that the radially extending bolt (22) is guided in the opening (39) only in the circumferential direction of the associated shaft part (12). 17. Shaft according to claim 11 or 12,
characterized, that the display shaft (32) is guided in a support (33) between the connection (17b, 17c) on the shaft part and the bolt (22) assigned to it.