SPRING DAMPER WITH TWO OVERLOAD PROTECTION COUPLINGS, AND POWERTRAIN

A spring damper for a motor vehicle drive train includes a primary part, a secondary part, a hub element, a first overload protection coupling operatively inserted between the secondary part and the hub element and a second overload protection coupling. The secondary part is rotatably received relative to the primary part in a spring-damped manner. The first overload protection coupling includes an output and the second overload protection coupling is operatively inserted between the output and the hub element. The second overload protection coupling is arranged radially within the first overload protection coupling. The first overload protection coupling is closed below a threshold of a torque to be transmitted, and the first overload protection coupling releases a relative rotation between the secondary part and the hub element above the threshold.

TECHNICAL FIELD

The present disclosure relates to a spring damper for a motor vehicle drive train, e.g., for a hybrid drive train of a motor vehicle, such as a car, truck, bus or other commercial vehicle, including a primary part, a secondary part which is rotatably received relative to the primary part in a spring-damped manner, and a first overload protection coupling. which is operatively inserted between the secondary part and a hub element. The first overload protection coupling is permanently closed below a threshold of a torque to be transmitted and releases a relative rotation between the secondary part and the hub element above said threshold at least in the event of an abrupt torque to be transmitted. In addition, the present disclosure relates to a drive train having this spring damper.

BACKGROUND

Spring dampers of the type in question used in drive trains are already well known in the prior art. For example, EP 2 765 331 A2 discloses a power transmission device having a damping component, a hysteresis generating component, and a speed limiting component.

Thus, spring dampers with torque limiters in the form of overload protection couplings are already known, wherein the torque limiters can also be used at different positions. However, it has been found that the spring dampers used often have a relatively complex structure with a large number of components and a relatively high mass inertia. The torque limiters are also usually positioned as close as possible to the damper springs in order to adequately protect this region in the event of a torque impulse. However, this means that the component of the spring damper that is further connected to the transmission input shaft during operation has a relatively high mass moment of inertia, which in turn can lead to relatively high torque loads on the part of the transmission input shaft and from there further in the transmission. The transmission input shaft and consequently the connected elements in the transmission, such as gears, etc., can thus be overloaded in certain operating states.

SUMMARY

The present disclosure provides a spring damper which is robust and durable, and which prevents overloading of a transmission connected in operation even when torque impulses occur.

According to the present disclosure, this is achieved in that a second overload protection coupling is operatively inserted radially within the first overload protection coupling between an output of the first overload protection coupling and the hub element. Consequently, a second overload protection coupling is now inserted in series with the previous first overload protection coupling. The second overload protection coupling is also designed in such a way that it is permanently closed below a threshold of a torque to be transmitted and releases a relative rotation between the output and the hub element above said threshold at least in the event of an abrupt torque to be transmitted, in particular in traction operation.

One overload protection coupling, in this case the first overload protection coupling, is inserted close to the damping mechanism of the spring damper, i.e., the damper springs, and another overload protection coupling, in this case the second overload protection coupling, is inserted close to the transmission input shaft. This provides reliable protection of both the transmission input shaft and the damping mechanism of the spring damper. The damper springs can be designed to be weaker and therefore more compact than in previously known variants.

In order to further reduce the torque load, the secondary part may have a flange element supported directly in the circumferential direction on a damper spring, which flange element in turn directly forms an input of the first overload protection coupling.

The overload protection couplings can also be produced easily if the output of the first overload protection coupling is formed by a multi-part support segment and at the same time forms an input of the second overload protection coupling.

The support segment may have a first disk region and a second disk region connected to the first disk region. The secondary part, e.g., the flange element, is clamped axially between the first disk region and the second disk region. The first disk region and the second disk region may each be formed as a sheet metal element/from a metal sheet. This allows the disk regions to be produced easily.

For the first overload protection coupling to be effective, the first disk region and the second disk region may each receive a friction lining (directly) bearing against the secondary part.

Production is further simplified if both the first disk region and the second disk region are each formed by a single sheet, which are axially spaced apart in the region of the friction linings, accommodating the flange element, and are in contact with one another radially within the friction linings/are axially supported against one another and are directly connected to one another there, e.g., by a riveted connection. This allows efficient assembly as well as attachment of the first and second disk regions to one another.

If the first disk region is also in contact with the primary part via a friction device, the damping effect of the spring damper is further improved.

Furthermore, the support segment may have a third disk region, which is connected to the second disk region, and the hub element is clamped axially between the second disk region and the third disk region. The third disk region may also be formed by a single sheet directly connected to the sheet of the second disk region. This also has a positive effect on the assembly and structure of the second overload protection coupling.

In this respect, the second disk region and the third disk region or the sheets forming these second and third disk regions may bear directly against one another radially outside multiple friction linings of the second overload protection coupling and may beattached to one another there, e.g., by means of riveting.

Accordingly, the second disk region and the third disk region may each receive a friction lining bearing against the hub element.

Furthermore, the present disclosure relates to a drive train for a motor vehicle, having a spring damper according to at least one of the embodiments described above. The primary part is connected to an output shaft of a motor and the hub element is connected to a transmission input shaft.

In other words, a spring damper, e.g., in the form of an arc spring damper, is thus implemented according to the disclosure, having a first radially outer slip coupling (first overload protection coupling) arranged near the arc springs (damper springs) and a second radially inner slip coupling (second overload protection coupling) arranged near the output shaft (i.e., near the transmission input shaft). Both slip couplings are connected in series and adjusted such that both the arc spring flange (flange element) and the transmission input shaft can, in each case, slip with a low mass moment of inertia in case of an impact.

DETAILED DESCRIPTION

The spring damper1according to the disclosure shown in the single FIGURE is inserted in operation in a drive train2of a motor vehicle, in this case a hybrid drive train2, which is indicated in principle. The spring damper1is operatively inserted between an output shaft of a motor, e.g., an internal combustion engine, which is not shown here for the sake of clarity, and a transmission input shaft of a transmission. Consequently, the spring damper1serves to dampen certain torque peaks that occur between the motor and the transmission during operation.

The spring damper1according to the single FIGURE has, on the one hand, a housing-like primary part3which, in operation, may be directly connected in a non-rotatable manner to the output shaft of the motor, which is not shown further for the sake of clarity. In addition to the primary part, the spring damper1also has a secondary part4rotatably received relative to the primary part3in a spring-damped manner. The primary part3and secondary part4are supported in a spring-damped manner relative to one another by means of several damper springs9arranged distributed in the circumferential direction, here in the form of arc springs.

In addition to the resilient support of the primary part3relative to the secondary part4by the damper springs9, an additional friction device17serves to generate the necessary damping effect, i.e., to convert the kinetic energy into waste heat. The friction device17is operatively inserted between the primary part3and the secondary part4and has an inhibiting effect on their relative rotation.

The secondary part4is formed substantially by a flange element10extending radially inwardly away from a region in contact with the damper springs9. A first overload protection coupling6is directly arranged/inserted on the flange element10. The flange element10thus directly forms an input11of the first overload protection coupling6and is operatively connected to an output8of the first overload protection coupling6via two (first and second) friction linings16a,16b. The first overload protection coupling6is implemented as a conventional slip coupling, which is permanently closed below a certain threshold of a torque to be transmitted and therein permanently connects the flange element10in a non-rotatable manner by frictional engagement with the output8of the first overload protection coupling6and releases/enables a relative rotation between the flange element10and the output8of the first overload protection coupling6when this threshold is exceeded, e.g., when a torque impulse occurs above the threshold.

With regard to the output8of the first overload protection coupling6, it is further shown that this is also formed by a multi-part support segment12. The support segment12has a first disk region14and a second disk region15fixedly connected thereto. The first disk region14and the second disk region15are guided radially within the first friction lining16aand the second friction lining16bwith one another, forming an axial shoulder19per (first and second) disk region14,15, and are in contact with one another. The two first and second disk regions14,15are connected together in this contact region by a first riveting20.

Radially outside this first riveting20, through the formation of the shoulder19, the two disk regions14,15are, in turn, axially spaced apart from one another and axially receive the flange element10between them, with the interposition of the respective friction lining16a,16b. The flange element10is thus clamped between the two disk regions14,15.

With regard to the first disk region14, it is also evident that it is continued radially outside the friction linings16a,16band forms a component of the friction device17. The first disk region14is thus also in frictional contact with the primary part3.

The support segment12also forms an input13of the second overload protection coupling7, so that the second overload protection coupling7is arranged in series with the first overload protection coupling6. On an axial side of the second disk region15facing away from the first disk region14, a third disk region18is attached to this second disk region15for this purpose. The second disk region15is connected to the third disk region18by a further (second) riveting21. In this embodiment, the second riveting21is arranged radially at the same level as the first and second friction linings16a,16b.

Radially within the second riveting21, the second and third disk regions15,18are axially spaced apart to one another by the respective formation of the shoulder19, and axially receive a hub element5or a flange region22of the hub element5, respectively, between them. It should be noted that the first riveting20is radially located at the level of the third and fourth friction linings16c,16d.

The flange region22is clamped between the second disk region15and the third disk region18in a manner similar to the clamping of the flange element10between the first disk region14and the second disk region15. Consequently, the flange region22is clamped axially between the second disk region15and the third disk region18with the interposition of a third friction lining16cand a fourth friction lining16d.

The function of the second overload protection coupling7is similar to the first overload protection coupling6. When a certain threshold of a torque/torque impulse to be transmitted is exceeded, the second overload protection coupling7opens automatically and thus allows the hub element5to rotate relative to the support segment12and consequently relative to the secondary part4, whereas below this threshold there is a non-rotatable connection between the hub element5and the support segment12. Consequently, the hub element5forms an output23of the second overload protection coupling7.

The third and fourth friction linings16c,16dare located radially within the first and second friction linings16a,16b. In addition, the friction lining assembly having the first and second friction linings16a,16bis arranged at least partially axially overlapping with the friction lining assembly having the third and fourth friction linings16c,16d.

With regard to the disk regions14,15,18, it should also be noted that these are each formed from a metal sheet. In this regard, the shoulders19may be produced using cold forming.

In other words, according to the disclosure, a damper (spring damper1) with a double torque limiter (first and second overload protection coupling6,7) is implemented. In this case, there is one torque limiter (second overload protection coupling7) that protects the transmission input shaft and another one (first overload protection coupling6) that protects the arc springs (damper springs9).

The concept is structured as follows: The hub (hub element5) serves as a rotating part in the torque limiter. It is placed between two coupling linings (third and fourth friction linings16c,16d) so that the slip function can be ensured in the event of an impact. The coupling linings are mounted on the support sheets (second disk region15and third disk region18). The support sheets are connected to one another by a riveting (second riveting21). These parts form that (second) torque limiter, which serves to protect the transmission.

The support sheet (second disk region15) is connected to the support sheet (first disk region14) by a riveting (first riveting20). The two coupling linings (first and second friction linings16a,16b) are mounted on the support sheets (first disk region14and second disk region15). The arc spring flange (flange element10) is located between the two coupling linings (first and second friction linings16a,16b). This serves as a rotating part in the torque limiter, so that the slip function can be ensured in the event of an impact. These parts form the (first) torque limiter, which protects the arc springs of the damper.

Both torque limiters are connected to one another via the support sheet (second disk region15) and form one and the same part (rigid connection) in normal traction operation. In traction operation, therefore, the mass moment of inertia of parts5,18,15,20,16c,16d,14,21,16a,16b,10acts on the transmission input shaft.

In the event of an impact (e.g., during emergency braking), the transmission input shaft and hub can slip with a very low mass moment of inertia on the transmission input shaft. In parallel, the arc spring flange can also slip separately with a very low mass moment of inertia on the arc spring. This concept allows for the design of optimal and soft arc spring characteristics with optimal protection functions.

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