Cardan joint with emergency running properties as well as driveshaft and motor vehicle with the cardan joint

Description

[0001] The present invention relates to a cardan joint and a corresponding drive shaft as well as a motor vehicle equipped therewith.

[0002] Universal joints (also known as cardan joints) and corresponding drive shafts are used in various applications, such as motor vehicles. In these applications, the cardan joints are often subjected to high loads. For example, DE 10 2008 049 348 A1 describes a universal joint arrangement for a drive shaft. This arrangement is designed to ensure maximum service life, particularly for heavy-duty drive shafts, while minimizing installation space. To this end, a bearing assembly for the journal of a pivot cross is provided in a fork bore of a joint fork. The bearing assembly includes a thrust bearing and a radial bearing for the journal, with the thrust bearing located in the area of ​​the journal shoulder. The fork bore has a flange on its side facing the axis of rotation of the drive shaft, while the journal shoulder has a contact surface.The axial bearing is positioned between the mounting surface and the mounting flange. This is intended to achieve a minimal path between force application and support of the axial bearing, enabling extremely robust axial bearing support and eliminating the need for additional mounting flanges for axial force support.

[0003] As a further example, DE 10 2012 109 475 B4 also describes a universal joint arrangement with two articulated forks and four pivot bearing assemblies. The latter comprise an outer sleeve arranged within a bearing bore of the articulated forks and having an end face on one side facing the center of the pivot cross. The pivot bearing assemblies further comprise an inner sleeve arranged within the bearing bore and having an annular section on one side facing the center of the pivot cross. An axial bearing is arranged between the end face of the outer sleeve and the annular section of the inner sleeve. The outer sleeve is axially supported against a fork arm of the articulated forks on one side of the bearing bore facing the center of the pivot cross. The annular section is spaced apart from the pivot cross, so that a gap is provided between the annular section of the inner sleeve and the pivot cross.In this way, the aim is to achieve the smallest possible external rotation diameter in the universal joint arrangement, while ensuring the best possible support for the axial bearing.

[0004] Such designs of universal joints or cardan joints can lead to improvements in normal, fault-free operation. However, they can also cause damage or failure of the bearings, i.e., bearing failure. In such a case, the pivot cross can shift relative to a joint fork, with one of the pins sliding further along its longitudinal axis through the fork bore than nominally or as specified for fault-free normal operation. This allows the components of the cardan joint to traverse or penetrate a larger space compared to fault-free normal operation, thus increasing the rotational diameter of the cardan joint.This can cause the cardan joint to come into contact with surrounding components, leading to further damage, or result in an unnecessarily large clearance around the cardan joint during normal, error-free operation, which can lead to inefficient use of installation space during normal, error-free operation.

[0005] WO 01 / 94 803 A2 describes a universal joint comprising a pair of forks, each fork having openings aligned through its respective cheeks in which annular rotary support members are arranged. The universal joint also comprises two pairs of opposing pins, each with a bearing, wherein at least the first pin of each pair of pins can be inserted from the outside into the respective annular rotary support members. Furthermore, a central support element, which positions the inner ends of the respective pins, and axial retainers, which secure the respective first pin against axial outward displacement, are provided.

[0006] US 1695,116A describes a universal joint with a fork having bearing sleeves at its ends, pins extending through the bearing sleeves toward the center of the fork, and rubber inserts between the bearing sleeves and the pins. The rubber inserts are locked to the bearing sleeves and the pins. The universal joint further includes a block with grooves to receive the pins and means for clamping the pins in the grooves.

[0007] DE 232 759 C describes a universal joint coupling in which the cross piece is composed of individual bolts. The bolts are connected by a pair of plates whose dividing line lies in the plane of the cross.

[0008] The object of the present invention is to provide a possibility for realizing improved emergency running properties of a cardan joint in the event of failure of a bearing of a pin in a joint fork of the cardan joint.

[0009] This problem is solved according to the invention by the subject matter of the independent claims. Possible embodiments and further developments of the present invention are disclosed in the dependent claims, the description, and the figures.

[0010] The universal joint or cardan joint according to the invention can be designed, for example, for a driveshaft or as part of a driveshaft. The cardan joint according to the invention has two articulated forks and a pivot cross. The pivot cross has a central body and four pins, the central bodies and their central longitudinal axes of which project outwards from the central body in two mutually perpendicular directions in a common plane. The central body and the pins can be formed in one piece or the pins can be received, for example, in corresponding receptacles in the central body. Pins arranged along a common central longitudinal axis can be different components or end pieces of a single continuous pin component, which can then, for example, extend through the central body.Each pin has a bearing point where it is supported in a corresponding fork bore of the pivot forks. Each pivot fork can have two fork arms arranged on opposite sides of the pin cross, each with a fork bore in which one of the pins is supported. The fork bores are therefore receptacles that can encircle each pin at its bearing point.

[0011] In the universal joint, or as part of the universal joint, at least one projection is formed next to at least one of the pins. This projection extends perpendicularly beyond the central longitudinal axis of the respective pin. The projection has at least one stop surface perpendicular to the common plane. This stop surface functions only in the event of a bearing failure of the respective pin, as a stop to support the pin cross against an inner surface of the corresponding joint fork facing the pin cross, thus limiting displacement of the pin cross relative to the corresponding joint fork along the central longitudinal axis of the respective pin.

[0012] The at least one feature is formed at least partially or completely, or exclusively, on the pivot cross. For example, the at least one feature can be formed on the central body of the pivot cross or on or beyond the pivot shoulder or pivot ridge of the respective pivot. Forming the at least one feature on the pivot cross can enable particularly simple manufacturing. In addition, any additional mass resulting from the feature can be positioned particularly close to a center of rotation of the universal joint, so that the corresponding additional load on the universal joint can be kept particularly low.

[0013] In the present invention, a corresponding feature is formed between and / or next to all pairs of adjacent journals. In other words, at least one such feature is arranged between all journals or next to each journal. This can provide particularly reliable support in various failure situations, i.e., in the event of the failure of any bearing.

[0014] Furthermore, this method allows for a particularly symmetrical design of the cardan joint, which can, for example, lead to or contribute to particularly smooth operation.

[0015] According to the invention, a recess is formed between adjacent projections when viewed perpendicular to the common plane, i.e., in the projection along the common plane, at the level of the central longitudinal axes of the pins. In other words, the projections in the common plane do not form a continuous shape, such as a continuous ring, a complete square, or a continuous plateau, but are separated or spaced apart from one another. Thus, viewed circumferentially around a central transverse axis of the pin cross perpendicular to the common plane, an alternating or interrupted pattern of projections and recesses results. These recesses can save material and weight. Furthermore, the recesses can optionally create or provide space for additional components or materials, a cooling airflow, or the like.Furthermore, this allows the contact surface, which acts as the contact area between the pivot cross and the respective joint fork in the event of bearing failure, to be reduced, thus minimizing friction losses. By selecting the appropriate material for the shape, sufficient strength can still be achieved to support the pivot cross and the forces or loads that occur.

[0016] The shape can, for example, be formed perpendicular to the common plane in which the tenons or their central longitudinal axes extend, i.e., viewed in projection into this plane, in an area at an angle lying in the plane between the central longitudinal axes of two adjacent tenons.

[0017] Adjacent cones, in the present sense, are cones whose central longitudinal axes are perpendicular to each other.

[0018] The shape can be arranged in the axial direction of the central longitudinal axis of the respective pin, in particular in front of and / or behind the bearing or a corresponding bearing point.

[0019] As intended, contact between the pivot cross and the corresponding joint fork only occurs at the molded area in the event of a bearing failure, where the bearing is damaged or has failed. In normal, error-free operation of the universal joint with bearings functioning according to specifications or intended use, there is no such contact, i.e., no support of the pivot cross on the joint fork via the molded area.

[0020] The additional design provided here, compared to conventional universal joints, allows the circumference, i.e., the extent of relative movement between the pivot and the joint fork, to be limited or reduced in the event of a bearing failure. This prevents the pivot or pivot from slipping or being forced too far through the fork bore. Thus, without altering or impairing the running characteristics of the universal joint during normal operation, an increase in the volume of space traversed by the universal joint in the event of a failure (i.e., with a defective, failed, or destroyed bearing) can be avoided or reduced. Therefore, the present invention enables a more efficient or space-saving design and improves the emergency running properties of the universal joint or the corresponding driveshaft compared to conventional universal joints.This can be achieved with drive shafts. The reduced or limited relative displacement of the pivot cross and the articulated forks not only prevents damage to surrounding components, but also reduces imbalances and corresponding torques. The latter can reduce the risk of further or permanent damage to the drive shaft and / or other bearings.

[0021] Emergency running properties of the cardan joint, in the present sense, are the running properties or mechanical properties of the cardan joint in the event of a bearing failure, i.e., with at least one damaged, failed, or completely or partially destroyed bearing of a journal in the corresponding fork bore.

[0022] In one possible embodiment of the present invention, during normal, fault-free operation, in which the bearing functions as intended or according to specifications, a gap, in particular an air gap, is present in the area of ​​at least one projection, i.e., in the area of ​​the stop provided for the event of a fault or failure of the bearing, so that there is then no contact between the pivot cross and the joint fork at the projection, the stop, or the stop surface. This avoids additional friction losses at the projection during normal, fault-free operation compared to conventional universal joints.

[0023] In a further possible embodiment of the present invention, the at least one feature is formed at least partially or completely or exclusively on the central body or as part of the central body. Forming the at least one feature on the pivot cross can enable particularly simple manufacturing. Furthermore, any additional mass resulting from the feature can be arranged particularly close to a center of rotation of the universal joint, so that the corresponding additional load on the universal joint can be kept particularly low.

[0024] In a further possible embodiment of the present invention, at least one projection is formed on both sides of the common plane. In other words, the projection, or a respective projection, can extend in both directions perpendicular to the common plane. This enables a symmetrical design of the pivot joint with respect to the common plane, which represents a central cross-sectional plane of the pivot joint. This can contribute to optimizing the smooth running of the universal joint and prevent or reduce tilting of the pivot joint or the central longitudinal axis of the respective pivot, whose bearing is damaged or destroyed in the event of a failure, relative to its intended or specified position during normal, fault-free operation.Such tilting could occur with one-sided support, i.e., if the molded shape is only formed on one side of the common plane, potentially leading to an increased risk of further damage, increased friction, or increased running vibration. This can be avoided or reduced by the design proposed here.

[0025] In a further possible embodiment of the present invention, a first stop surface of the mold is formed perpendicular to the central longitudinal axis of the first pin, and a second stop surface of the mold is formed perpendicular to the central longitudinal axis of the adjacent pin, which in turn is perpendicular to the central longitudinal axis of the first pin. This means that the two stop surfaces are also perpendicular to each other. The mold has a chamfer between these mutually perpendicular stop surfaces, i.e., a chamfered side relative to each of the two stop surfaces, which is perpendicular to the bisector of the angle between the central longitudinal axes of the two pins in the common plane. The chamfer, i.e., the chamfered side or outer surface, can therefore, for example, be at an angle of 45° to each of the stop surfaces.The chamfer, i.e., the beveled or angled side, is therefore neither perpendicular nor parallel to a central longitudinal axis of the pins. The design proposed here can be used particularly when at least one feature is formed on the central body of the pin assembly. The chamfer proposed here allows for particularly easy installation of the pin assembly or particularly easy assembly of the universal joint.

[0026] In a further possible embodiment of the present invention, the shape is formed partially on the inside of at least one of the joint forks. In other words, it is possible to form the shape partially on the side of the pivot cross and partially on the side of the joint forks. This provides corresponding flexibility with regard to the design of the universal joint according to the invention, allowing different requirements, for example, regarding manufacturing, installation space requirements, or other properties, to be met. By forming the shape partially on at least one of the joint forks, the material required for the shape can be partially saved if only the pivot cross needs to be replaced after a bearing failure. This can potentially lead to more cost-effective maintenance or repair.

[0027] By partially forming the recess on the pivot cross or as part of the pivot cross on the one hand, and on or as part of at least one of the joint forks on the other, it can be ensured particularly easily and reliably that, in the event of a bearing failure, contact or abutment between the two parts of the recess is established or occurs in the intended manner. This allows for a particularly low-friction emergency running operation to be achieved, for example, through appropriately coordinated design and / or material selection of the recess parts, especially without having to adjust the properties of other components or areas of the universal joint intended for fault-free normal operation.

[0028] Another aspect of the present invention is a driveshaft comprising a first shaft section and a second shaft section, as well as a universal joint according to the invention that couples the two shaft sections together. The driveshaft according to the invention can, in particular, be the driveshaft mentioned in connection with the universal joint according to the invention, or correspond to it. Accordingly, the driveshaft according to the invention can have some or all of the properties and / or features mentioned in connection with the universal joint according to the invention.

[0029] Another aspect of the present invention is a motor vehicle comprising at least one universal joint and / or at least one driveshaft according to the invention. The motor vehicle according to the invention can be, in particular, a motorcycle, but is not limited to this. A motor vehicle can represent a particularly useful application for the driveshaft or universal joint according to the invention, since improved emergency running properties and a reduced risk of damage to surrounding components can enable the motor vehicle to continue driving under its own power, for example, to a workshop, even in the event of bearing failure. Thus, the present invention can achieve improved user comfort and reduce the effort required in the event of a failure. Furthermore, the improved emergency running properties of the universal joint or driveshaft according to the invention can...The inventive drive shaft improves safety in the operation of the motor vehicle.

[0030] Further features of the invention may become apparent from the claims, the figures, and the description of the figures. The features and combinations of features mentioned above in the description, as well as the features and combinations of features shown below in the description of the figures and / or in the figures themselves, can be used not only in the combinations specified, but also in other combinations or individually, without departing from the scope of the invention.

[0031] The drawing shows in: Fig. 1 a schematic perspective view of a conventional pivot joint for a cardan joint according to the prior art; Fig. 2 a schematic perspective view of an improved pivot joint for a cardan joint with improved run-flat properties; Fig. 3 a schematic side view of an improved cardan joint; Fig. 4 a schematic cross-sectional view of a conventional cardan joint according to the prior art; and Fig. 5 a schematic cross-sectional view of an improved cardan joint

[0032] In the figures, identical and functionally equivalent elements are each provided with the same reference symbols.

[0033] Fig. 1 Figure 1 shows a schematic perspective view of a conventional standard tenon cross 1 according to the prior art. The standard tenon cross 1 has a central body 2 and tenons 3 projecting from it. The tenons 3 lie in a common plane and extend in two directions perpendicular to each other in this common plane, resulting in a cross-shaped arrangement. Each tenon 3 has a narrower end section and, towards the center of the central body 2, a widened tenon shoulder 4. At each angle 5, i.e., in a corner region between two adjacent tenons 3, the central body 2 of the standard tenon cross 1 is reduced as much as possible, i.e., its design is minimal. This allows the standard tenon cross 1 to slide longitudinally through a receptacle along one of the tenons 3, for example, in the event of a bearing failure.This is related to . Fig. 4 explained in more detail.

[0034] Fig. 2 Figure 1 shows a schematic perspective view of a tenon cross 6 improved compared to the standard tenon cross 1. The tenon cross 6 also has a central body 2 and four tenons 3 projecting from it in a common plane in two mutually perpendicular directions. In the tenon cross 6, the central body 2 has a projection 7 at each of the angles 5, i.e., between two adjacent tenons 3 or in a transition area between two adjacent tenon shoulders 4. These projections 7 extend perpendicularly beyond the tenons 3 to the common plane, which forms a central cross-sectional plane of the tenon cross 6. The projections 7 thus form respective stops or stop surfaces 8, which are arranged or extend at least substantially perpendicular to the common plane of the tenons 3.

[0035] In the event of a bearing failure, the pivot cross 6 cannot slide through a corresponding receptacle or pivot bearing of one of the pins 3 as far as the standard pivot cross 1 until the adjacent pins 3 strike another component. Instead, this sliding, i.e., the movement of the pivot cross 6 in the longitudinal direction of one of the pins 3, is limited by the projections 7, namely only permitted until the respective stop surface 8, extending perpendicular to the direction of movement, i.e., to the longitudinal direction of one of the pins 3, strikes, i.e., comes into contact with another component.

[0036] The projections 7 are each designed with a chamfer 9, which is inclined, in particular at an angle other than 0° and 90°, especially at an angle of 45°, to the stop surfaces 8 of the respective projection 7. This chamfer 9 in the area of ​​the respective angle 5 allows for simplified installation of the pin cross 6.

[0037] For further illustration, the central longitudinal axes 10 of the cones 3 are indicated here. These central longitudinal axes 10 lie in the aforementioned common plane and thus intersect at the center of the cone cross 6 or the central body 2.

[0038] Viewed laterally, i.e., perpendicular to the common plane or the central longitudinal axes 10, the projections 7 are arranged on the respective side of the pivot cross 6 or the central body 2 along the line of an imaginary circle or an imaginary square. Along this line, the projections 7 are spaced apart from one another by intervening recesses 11. The recesses 11 are each located in the area of ​​one of the pivots 3, i.e., at the level of one of the central longitudinal axes 10, while the projections 7 are located between the pivots 3, that is, in the corners or angles between the central longitudinal axes 10. The recesses 11 can be useful, for example, to save material and weight and to provide accessibility or guidance. However, the illustrated design or arrangement is to be understood as an example, so that other arrangements or designs are also possible.For example, the recesses 11 can be omitted to enlarge the stop surfaces 8, additional shapes 7 can be provided in the recesses 11 and / or additional recesses 11 in the area of ​​the shapes 7 shown, and / or the like.

[0039] Fig. 3 Figure 1 shows a partial schematic side view of a drive shaft 12 with a correspondingly improved cardan joint 13. The cardan joint 13 comprises the pivot cross 6 and two joint forks 14. The joint forks 14 each have two joint arms that receive or hold pins 3 arranged on opposite sides of the central body 2.

[0040] In the situation depicted here, involving a bearing failure, one of the pivot forks 14 is displaced upwards along the central longitudinal axis 10 running in the plane of the drawing. This exposes, and thus reveals, a bearing point 15 of the opposite journal.

[0041] In the embodiment shown here, the articulated forks 14 also have fork-side projections 16 which have the same function as the described projections 7 of the pivot cross 6. For example, in the event of a bearing failure, the fork-side projection 16 can abut the corresponding stop surface 8, i.e. be supported, in order to prevent further displacement of the pivot cross 6 relative to the articulated forks 14.

[0042] Fig. 4 Figure 1 shows a schematic cross-sectional view of a standard universal joint 17 with a bearing failure. A nominal center point 18 is indicated where the central longitudinal axes 10 of the journals 3 intersect during normal, fault-free operation. This is illustrated by an indicated nominal position 19 of one of the central longitudinal axes 10, where the corresponding central longitudinal axis 10 passes through the nominal center point 18. In contrast, in the fault case shown here, the standard journal cross 1 is displaced along one of the central longitudinal axes 10 relative to the joint forks 14, such that the second central longitudinal axis 10, which runs perpendicular to it, is now in a position 20 that is parallel to the nominal position 19. Thus, the standard journal cross 1 is significantly deflected from its intended position. This inevitably leads to the enlargement of the outer rotation circle 21 indicated here.

[0043] The outer circle of rotation 21 encompasses or marks the area of ​​space that passes through or sweeps over when the standard universal joint 17 rotates about its axis of rotation, which here is perpendicular to the plane of the drawing. By moving the standard pivot cross 1, the diameter 22 of the outer circle of rotation 21 increases, so that in a corresponding fault condition the standard universal joint 17 requires more space or can come into undesirable contact with surrounding components.

[0044] Through the described design measures on the improved pivot cross 6 and / or the joint forks 14, in the event of a bearing failure of one of the pivots 3, the outer circle of rotation 21 or its diameter 22, as it exists during normal, fault-free operation, can at least be almost maintained, or its enlargement can be reduced, at least compared to the standard universal joint 17. This can be achieved by means of corresponding webs or contours, in this case the features 7 and / or the fork-side features 16. [Figure 1] Fig. 5A schematic cross-sectional view of the universal joint 13 in a corresponding fault condition. In the event of damage or failure of a bearing, the pivot 6 can then be supported on these webs or projections 7, 16 within the cardan shaft forks 14. Thus, despite the failure of the bearing and the associated at least potential displacement of the pivot 6 relative to the cardan shaft forks 14, the rotational diameter of the universal joint 13 or the corresponding cardan shaft 12 is not increased or is only increased slightly. This prevents the corresponding pin 3 from moving or shifting outwards through the respective fork bore 23. In other words, this prevents a pin end 24 of the corresponding pin 3 from coming into contact with surrounding components and causing consequential damage.

[0045] Overall, the examples described show how an improvement in the emergency running properties of a universal or cardan shaft can be achieved. Reference symbol list

[0046] 1 Standard pivot 2 Central body 3 Peg 4 Peg shoulder 5 Angle 6 Peg cross 7 Shape 8 Stop surface 9 Chamfer 10 Central longitudinal axis 11 Recess 12 Cardan shaft 13 Universal joint 14 Fork 15 Bearing point 16 Fork-side shape 17 Standard universal joint 18 Nominal center 19 Nominal position 20 Offset position 21 Outer circle of rotation 22 Diameter 23 Fork bore 24 Peg end

Claims

1. Universal joint (13), comprising two joint forks (14) and a cross piece (6) with a central body (2) and four pins (3) protruding from the central body (2) in a common plane in two directions perpendicular to each other, each having a bearing point (15) at which the respective pin (3) is mounted in a respective corresponding fork bore (23) of the joint forks (14), wherein beside at least one of the pins (3) at least one formation (7, 16) is formed which protrudes beyond the pin perpendicular to the central longitudinal axis (10) of the respective pin (3) and has at least one stop surface (8) perpendicular to the common plane, which only in the event of a failure of a bearing of the respective pin (3) acts as a stop (8) for supporting the cross piece (6) on an inner side of the corresponding joint fork (14) facing the cross piece (6) to limit a displacement of the cross piece (6) relative to the corresponding joint fork (14) along the central longitudinal axis (10) of the respective pin (3), the formation (7) is formed at least partially on the cross piece (6) and a corresponding formation (7) is formed between and / or beside all adjacent pins (3), characterized in that when viewed perpendicularly to the common plane along the central longitudinal axes (10) of the pins (3), a recess (11) is formed between adjacent formations (7).

2. Universal joint (13) according to claim 1, characterized in that in error-free normal operation, a distance, in particular an air gap, is present in the area of the formation (7, 16), so that there is then no contact between the cross piece (6) and the joint fork (14) at the formation.

3. Universal joint (13) according to any one of the preceding claims, characterized in that the formation (7) is formed at least partially on the central body (2) of the cross piece (6).

4. Universal joint (13) according to any one of the preceding claims, characterized in that the formation (7, 16) is formed on both sides of the common plane.

5. Universal joint (13) according to any one of the preceding claims, characterized in that a first stop surface (8) of the formation (7) is formed perpendicular to the central longitudinal axis (10) of the respective pin (3), a second stop surface (8) of the formation is formed perpendicular to the central longitudinal axis (10) of an adjacent pin (3) and the formation (7) has a chamfer (9) between these stop surfaces (8) which is perpendicular to the angle bisector of the angle (5) between the central longitudinal axes (10) of the two pins (3) in the common plane.

6. Universal joint (13) according to any one of the preceding claims, characterized in that the formation (16) is formed partially on the inner side of at least one of the joint forks (14).

7. Cardan shaft (12), comprising a first shaft piece and a second shaft piece and a universal joint (13) according to any one of the preceding claims, which couples the first shaft piece and the second shaft piece to each other.

8. Motor vehicle, comprising a universal joint (13) according to any one of claims 1 to 6 and / or a cardan shaft (12) according to claim 7.