DE102015200384A1 - Damper unit for a suspension system with a semi-active damping means - Google Patents

Abstract

The invention relates to a damper unit (1) for a suspension system of a vehicle. This comprises a semi-active damping means (2) and a spring travel limiter (6) with an at least partially elastically formed base body (7). The damping means (2) has a cylinder tube (3) and in the cylinder tube (3) linearly displaceably mounted piston rod (4), which is at least partially surrounded by the Federwegbegrenzer (6). According to the invention, the base body (7) has at least one sensor unit (12) which is designed to monitor a compression of the base body (7) in its longitudinal direction (x).

Description

The present invention relates to a damper unit of a semi-active damping means of a suspension system of a vehicle according to the preamble of claim 1.

Suspension systems used in vehicles primarily serve to decouple the vehicle body from the ground to be driven. Typically, this damping means are used in the form of shock absorbers. These usually have a filled with a medium such as oil and / or gas cylinder tube, wherein the medium may be pressurized. Furthermore, a piston rod is provided which is mounted linearly displaceable linearly displaced in the cylinder tube. In addition to conventionally installed passive damping means active damping agents have already established. Active damping means have the advantage that their characteristics and thus the tuning of the damping behavior is also changeable during operation. On the other hand, purely passive damping means require already during installation a determination on their respective vote, which requires a compromise between the typically directed to them requirements in terms of vehicle stability, safety and comfort.

Active damping means can be distinguished essentially into semi-active and fully active embodiments. While semi-active damping means are usually completed with a Federwegbegrenzer to a damper unit and combined for example with a vehicle spring, fully active damping means only an actuator available. This actuator alone is capable of providing the required actuating forces to carry and damp the mass of the vehicle body in motion. For this purpose, a sometimes complex stability-securing control of the individual actuators is required. Compared to semi-active damping means required for a fully active design actuators, however, require a high placement energy to generate the necessary restoring forces between the vehicle body or frame and, for example, a wheel of the vehicle in both directions (rebound).

In contrast, combined with suspension springs semi-active damping means are able to carry the vehicle body due to the spring load without energy consumption. The suspension springs may be formed, for example, as leaf springs or coil springs. The latter can also be offset parallel or at least partially arranged around the damping means. In this arrangement, a semi-active damping means and a suspension spring comprehensive damper units only by design allow the construction of an already stable in itself suspension system, which includes one of the respective direction of movement always opposite stabilizing force development.

Although suspension systems with active damping devices are a well-developed and popular technology, the drive for further developments is intended to make variable suspension systems more efficient and affordable overall. For this purpose, in particular semi-active damping means for the construction of semi-active suspension systems, which can be compared to fully active embodiments achieve corresponding cost advantages. In this respect, built with semi-active damping means variable suspension systems one of the cheap key technologies to improve the ride comfort and safety, especially of passenger vehicles.

In order to adapt the characteristic of the semi-active damping means in the installed state to the respective requirements, various proposals from the prior art are already known:
For example, the US 5,088,760 A and the DE 40 21 909 A1 in each case a control for a variable suspension system of a vehicle. The goal is to set a suitable damping characteristic of the semiactive damping means from "soft" to "hard". For this purpose, the arrangement of a first measuring means for detecting the relative speed between the incoming and auszufating vehicle wheel as unsprung mass and the corresponding sprung mass in the form of the vehicle body is proposed. Another second measuring means is used to detect the vertical acceleration of the vehicle body, wherein a third means processes the signals generated by the measuring means. As a result, a triggering signal is generated with which a damping means changing the damping characteristic of the semiactive damping means is controlled. The damper unit comprising the damping means and a suspension spring has an upper spring plate, against which the suspension spring is braced. Above the spring plate, a further sensor is arranged within an elastic body, which serves to measure the weight load of the vehicle. About said elastic body, the damper unit is supported against the vehicle body.

A similar structure is from the US 5,390,121 A which is also directed to a variable suspension system for a vehicle having semi-active damping means. The respective damping means comprises an adjustable valve to change the damping characteristic between an "on" and an "off" position. Here too the arrangement of several sensors is proposed, which detect, for example, the vertical acceleration of the vehicle body and the relative speed between the incoming and auszufating vehicle wheel and the vehicle body.

From the US 2004/0254701 A a scheme for a variable suspension system for a vehicle with semi-active damping means emerges. This is based on the detection and evaluation of several signals such as the vertical acceleration of the vehicle body as well as the relative speed between the incoming and auszufating vehicle wheel and the vehicle body.

The US 7,672,766 B2 proposes for a device for controlling a variable suspension system with semi-active damping means also several measuring means. In addition to the arrangement of measuring means for the vertical acceleration of the vehicle body as well as the relative speed between the cushioned and rebounding vehicle wheel and the vehicle body, this provides a further measuring means to detect the load on the vehicle.

Of the US 6,847,874 B2 is a method for controlling and controlling semi-active damping means of a damper system for vehicles refer. This provides for the regulation of the damping characteristic as a function of the detected speed of the damping means via distance sensors. For this purpose, a subtraction of the thus detected signals over a specified time difference.

Furthermore, the shows US 5,467,280 A a variably adjustable damper unit which can be arranged between a vehicle body and a vehicle wheel. The damper unit comprises a semi-active damping means and at least one sensor for determining an absolute vertical speed of the vehicle body as a sprung mass. Depending on the thus detected vertical speed, the damping characteristic of the damping means can then be changed via a control unit.

The embodiments of variably modifiable semi-active damping means proposed in the prior art include a sometimes complex control, which requires correspondingly many and complex measuring means as well as processing of the signals generated by the measuring means suitable processing means. Overall, the previously known solutions for variable adjustment of such damping means therefore require a variety of additional components and a sometimes complex control. Against this background, semi-active damping means therefore still offer room for improvement with regard to the sometimes complex structure of the required peripherals.

Against this background, the invention has the object, further develop a semi-active damping means with a Federwegbegrenzer comprehensive damper unit to the effect that the control of the semi-active damping means underlying events in a simple and cost-effective manner can be detected and / or measured.

This object is achieved by a damper unit having the features of claim 1. Further, particularly advantageous embodiments of the invention disclose the respective subclaims.

It should be noted that the features listed individually in the following description can be combined with one another in any technically meaningful manner and show further embodiments of the invention.

The description additionally characterizes and specifies the invention, in particular in connection with the figures.

Hereinafter, a damper unit is shown, which is suitable for use for a variable suspension system of a vehicle, in particular a motor vehicle. The damping unit according to the invention for a suspension system of a vehicle has a semi-active damping means and a Federwegbegrenzer with an at least partially elastic base body, wherein the damping means has a cylinder tube and a linearly displaceably mounted in the cylinder tube piston rod, which is at least partially encompassed by the Federwegbegrenzer. The damper unit according to the invention thus comprises a semi-active damping means, which may be advantageously designed as a typical shock absorber. For this purpose, the damping means may preferably have a cylinder tube filled, for example, with a medium, in which a piston rod is mounted linearly displaceable. According to the invention, the base body has at least one sensor unit, wherein the sensor unit is designed to monitor a compression of the base body in its longitudinal direction.

The semi-active damping means is thus characterized by the fact that it allows a change, in particular a change in its vote. Thus, the semi-active damping means may be particularly preferably at least switchable between a "soft" and a contrast "hard" vote. A soft vote here means that when dipping the piston rod into the cylinder tube takes place Damping (compression) can be designed rather comfortable and / or allows a correspondingly long travel. In contrast, a hard vote means that when dipping the piston rod takes place in the cylinder tube damping (pressure level) can be designed rather sporty and / or allows a correspondingly short travel.

A hard vote is for example in such driving situations of advantage, in which the possible travel, for example, by strong lateral inclination (cornering) and / or when driving on an uneven ground to a large extent claimed. Due to a then possible switch to a rather hard vote a possible penetration of the damping means is effectively counteracted. In addition, can be met in this way too strong lateral inclination of the vehicle body, for example in curves. Of course, the characteristic of the semi-active damping means in its rebound (rebound) be changed by the switching of the vote accordingly.

The damper unit according to the invention further comprises at least one Federwegbegrenzer, which has an at least partially elastic base body. Particularly preferably, the spring travel limiter can be arranged so that it surrounds the piston rod of the damping means at least in regions. In this arrangement, the spring travel limiter forms a kind of buffer between a bearing receiving the free end of the piston rod and, for example, an end face of the cylinder tube facing this bearing. The storage may be, for example, an area of a body and / or a frame or subframe of the vehicle.

Particularly preferably, the damper unit, at least in the state installed on a vehicle, can also be combined with a suspension spring, which can be arranged at least partially around the damping means of the damper unit, either parallel to the damper unit or, for example, in the form of a helical spring.

According to the invention, it is now provided that the base body has at least one measuring means, for example in the form of a sensor unit. The sensor unit can be arranged, for example, in or on the base body of the spring travel limiter. In any case, the sensor unit is designed to monitor a possible compression of the damping means possible compression of the base body in its longitudinal direction. Monitoring means in the sense of the invention that the sensor unit is to detect a potential compression of the spring travel limiter and to generate a corresponding signal, which, in addition to the mere reporting of a compression, may also include a value about the strength and / or speed of the compression.

Thanks to the embodiment of the invention, it is now possible to use the entering in different driving situations at least partial compression of Federwegbegrenzers to make on this basis a possible switching of the semi-active damping means in its vote. Depending on the length of Federwegbegrenzers with respect to the available travel can be selected whether a already entering at small amplitudes of the damping means contact the Federwegbegrenzers to trigger a corresponding signal with him upsetting areas.

Thus, for example, compared to the possible travel short Federwegbegrenzer to the fact that its compression takes place only in extreme situations in which the piston rod, for example due to a pronounced bump and / or a strong lateral inclination of the vehicle body dives deep into the associated cylinder tube of the damping means. A correspondingly long embodiment of the spring travel limiter naturally leads to even small movements in the direction of deflection of the damping means leading to an at least partially upsetting event of the base body of the spring travel limiter. In this way, a switch in the vote of the semiactive damping means can already be enforced at low amplitudes.

The resulting advantage lies in a very compact and simple and therefore cost-effective design for such a damper unit, which manages with a minimum of components in particular for the necessary control of the semi-active damping means. Furthermore, the embodiment according to the invention offers a high degree of flexibility with regard to the tuning or the control strategy of the suspension system that can be built therewith. Thus, while maintaining the semi-active damping means a corresponding change can be made by only the sensor unit having Federwegbegrenzer is replaced.

According to an advantageous development of the basic idea of the invention, the semi-active damping means can have at least two-stage tunability. In other words, the damping means can then be switched between at least two states with regard to its tuning. In practice this can be done, for example, by manipulating at least one flow rate of a medium arranged in the damping means, such as oil and / or gas regulating valve. Particularly preferred may the semi-active damping means between a soft vote and a contrast hard vote reversibly be switched. In this way, depending on the monitored compression of the spring travel limiters - and due to the conclusions drawn therefrom with respect to a setting adapted for this purpose - it is possible to switch over between a comfortable or, in contrast, sporty tuning of the damping means. In this way, a limitation of the possible travel can be done by the semi-active damping means, for example, in the hard (sporty) tuning is switched.

In principle, it is provided that the basic setting of the semiactive damping means includes its soft (comfortable) tuning. As a result, a high level of ride comfort for or the respective occupants of the vehicle is achieved. Thus, a switch to the hard (sporty) vote only in appropriate driving situations, which in this setting, for example, allows a simpler and / or safer handling of the vehicle. Subsequently, the semi-active damping means after a certain time and / or a certain distance and / or a change in the detected amplitudes can be switched back to its default setting and thus back to its contrast soft vote.

Thanks to the previously proposed damper unit according to the invention, it is now possible to realize the advantages of a variable suspension system with the help of at least one semi-active damping means inexpensively and with a high degree of flexibility.

The invention further relates to a spring travel limiter, which is suitable for combination with a semiactive damping means to a damper unit. Particularly preferably, the damper unit thus created can be the previously disclosed damper unit according to the invention for a variable suspension system of a vehicle.

The aim is that the sensor unit can preferably be arranged in or at a free end portion of the base body. The end section should be that end section of the base body which can come into contact with the cylinder tube during compression of the damping means and thus from a predetermined insertion depth of the piston rod into the cylinder tube. In this case, the contact can be made, for example, between an end face of the cylinder tube facing the spring travel limiter and the end section of the base body.

Thanks to this design, a potential compression of the spring travel limiter can already be detected at the beginning and a corresponding signal can be triggered. The further the position of the sensor unit is away from the end section of the base body, the later the sensor unit can react to a compression of the spring travel limiter. This is essentially due to the elastic configuration of the base body. Thus, the lying between the sensor unit and the free end of the end portion of the base body may already be subject to compression, without this has propagated up to the sensor unit out.

Of course, this knowledge can also be used to set the response of the sensor unit in this way. In other words, an arrangement of the sensor unit lying far from the free end of the end section can be used to detect only strong upsets of the spring travel limiter, which already extend into a large part of its base body.

Furthermore, it is considered to be particularly advantageous if the base body has an outer circumferential surface which is inclined with respect to its longitudinal direction. As a result, the base body from the outside substantially have the shape of a cone or a truncated cone. However, this embodiment is limited to a smooth outer surface of the base body. Thus, the outer shape, which can also be referred to as a conical shape, can be composed, for example, of different structures, such as, for example, protruding and / or recessed segments, which thus bring about in their entirety the described outer shape shape in their entirety.

Next, the invention provides that the base body has a built-in state, for example, the piston rod facing the inner lateral surface, which in contrast to the outer surface extends purposefully parallel to the longitudinal direction of the base body. This is advantageous insofar as this results in a very precise guidance of the spring travel on the piston rod of the damping means. In particular, in a compression of the travel limit this is then largely without a possible buckling out of the longitudinal direction of the base body out.

Due to the course of the inner and outer lateral surface of the base body as described above, naturally, a thickness of its wall changing over the longitudinal direction of the base body arises. From this it is now possible to obtain a very advantageous progressive compression behavior of the base body. In other words, the portion tapered from the rest of the base body can be compressed relatively easily, whereas compression of the remaining ones is possible Parts a preferably progressively increasing force on the base body requires. As a result, large amplitudes can be safely intercepted and / or mitigated by the spring travel limiter, despite the high energy content, without resulting in undesirable penetration of the semiactive damping means.

In combination with the position of the sensor unit, this progressive configuration of the base body can be used to adjust the response of the sensor unit. In particular, possible by the sensor unit measurement of the amount of compression can be done in this way in the form of a flatter rise of the signals generated for this, since the possible bandwidth of the measurable by the sensor unit compression otherwise may be exceeded even at medium compression.

According to a particularly preferred further development, the sensor unit may comprise not only a single, but at least two or more individual sensors. In an advantageous manner, the individual sensors can be arranged in or on the base body of the spring travel limiter in such a way that they form a type of stack. In other words, it is considered advantageous if the individual sensors are arranged one behind the other in relation to the longitudinal direction of the base body. Of course, the successive sensors can also follow a length inclined with respect to the longitudinal direction. Rather, it is important here that the individual sensors are not arranged together in a single plane extending transversely to the longitudinal direction, but in mutually different planes.

In this way, the invention makes use of the findings already explained in more detail above, such that the individual sensors detect, as it were, an increasing compression of the base body in succession. Since the compression usually begins at the free end of the travel limit, the sensors are addressed only with their increase from the free end further away. Hereafter, only a detection of a compression by the individual sensors would be required, since the amount of compression can be derived by the number of detected the compression sensors. Also, the speed of compression can be determined by the time between the detection of the successively arranged sensors is detected. Because the faster the successive sensors report a compression, the higher must be the speed of the underlying compression and vice versa.

In this way, a very simple construction with correspondingly inexpensive sensors is possible, which need only serve to detect a compression but not necessarily even the detection of the strength and / or speed of compression. It is also within the meaning of the invention, when only a single sensor is arranged in advance in a certain position seen in the longitudinal direction, wherein the selected position corresponds to the desired adjustment strategy.

Furthermore, the invention is also directed to a method for operating a damper unit for a suspension system of a vehicle, which has a semi-active damping means together with spring travel. The method particularly preferably serves to operate a suspension system composed of the above-described damper unit according to the invention and spring travel limiters. The method provides that the semiactive damping means can be switched at least between a soft vote and a hard vote.

The actual switching in the vote of the semi-active damping means is carried out according to the invention based on a detected by the sensor unit compression of the base body. Alternatively or in addition to this, the switching is performed on the basis of a measured compression of the base body. The difference between detection and measurement of the compression is seen in the sense of the invention in that a pure detection first contains information about the fact of a compression, whereas a measurement quantifies the compression to what extent and / or at which speed it exists or . has occurred.

The resulting advantages have already been explained previously in connection with the damper unit according to the invention and the spring travel limiter according to the invention and apply correspondingly to the method according to the invention. Incidentally, this also applies to the further advantageous embodiments of the method according to the invention which are named below, so that reference is made at this point to the previous statements on this point.

Thus, a measure of the method according to the invention can provide that the switching of the semi-active damping means is carried out in its vote on the basis of exceeding a previously defined threshold value. Possible threshold values can be present, for example, for the detected width of the compression, which, if exceeded, can be used to switch from soft to hard, for example. An alternative or supplementary threshold can be used, for example the detected and / or determined speed of the compression occurring can be stored, beyond which said switching of the semi-active damping means can be carried out.

With regard to the typical structure of a suspension system for a multi-lane vehicle, which comprises at least three or mostly four damper units, the exceeding of at least one threshold at at least one damper unit can basically be used to switch only the semi-active damping means of the associated damping unit detected. Alternatively, the overshoot on only one of the damping units can be used to switch over at least one more or even all damping units. Depending on the driving situation, it may thus be useful to switch, for example, damping units located on one side of the vehicle at the same time. It is also conceivable to switch crosswise to obtain a mixture in the damping characteristic while maintaining a high vehicle stability.

According to a further measure according to the invention, the method can also provide for the above-described options for switching one or more damper units not only on the basis of the exceeding of a threshold value, but in an additional dependency on a predetermined period for the respective exceeding of the threshold value. Alternatively, the switching can of course be made only in response to a predetermined period for the exceeding of a threshold value.

The sensor unit is purposefully connected to a control unit which generates the corresponding signal for switching. The control unit may be the central control unit of the vehicle itself or integrated in it.

Further advantageous details and effects of the invention are explained in more detail below with reference to an embodiment schematically illustrated in the figures. Show it:

1 a damper unit according to the invention in a side view with partially cut representation and

2 the damper unit according to the invention 1 in an alternative embodiment of one of its components in otherwise identical representation.

In the different figures, equivalent parts are always provided with the same reference numerals with respect to their function, so that these are usually described only once.

1 shows a damper unit according to the invention 1 which typically serves to construct a variable suspension system not shown in detail for a likewise not shown vehicle. For this purpose, the damper unit comprises 1 a semi-active damping agent 2 , which is exemplified as a shock absorber. In this embodiment, the semi-active damping means 2 a cylinder tube 3 and a piston rod 4 , where the piston rod 4 linearly displaceable in the cylinder tube 3 is stored. Inside the cylinder tube 3 may be arranged a not clarified medium, for example, oil and / or gas. Also, the medium may already be pressure loaded. By this construction, the piston rod 4 if necessary in the cylinder tube 3 immerse, creating the semiactive damping means 2 provides a travel A.

As can be seen, this is semi-active damping means 2 over the free end of its piston rod 4 with a storage 5 connected. During storage 5 For example, it may be a region of a structure or frame or subframe of a vehicle in a manner not shown in greater detail. Between the cylinder tube 3 and storage 5 is a spring travel limiter 6 arranged. This has an at least partially elastic base body 7 on which the piston rod 4 of the semiactive damping means 2 at least partially encompasses. Overall, the semi-active damping means 2 an at least two-stage tunability, which allows at least a switch between a soft vote and a hard vote.

If 1 also not directly removable, so it is the base body 7 preferably around a body rotationally symmetrical about its longitudinal axis x. This extends the base body 7 not only in the longitudinal direction x and one with respect to the representation of 1 in sheet plane extending transverse direction y, but also in a directed in sheet depth direction z.

Obviously, the spring travel limiter 6 while a substantially conical shape, so that the base body 7 from a substantially cylindrical base element 7a to a front page 8th of the cylinder tube 3 rejuvenated. For this purpose, an outer lateral surface 9 of the base body 7 relative to its longitudinal direction x correspondingly inclined, while one of the piston rod 4 facing inner lateral surface 10 of the base body 7 runs substantially parallel to the longitudinal direction x. Due to the thickness b of the base body, which thereby changes over the longitudinal direction x 7 becomes a progressive one Compression behavior of Federwegbegrenzers 6 reached. The in 1 represented conically tapered base body 7 has a corrugated, so step-like design, so that the enveloping lateral surface 9 results. Of course, a continuous version of the conical section is also possible.

In the present case is said Federwegbegrenzer 6 shown in a sectional view, in particular to take a look in the base body 7 into and onto the piston rod engulfed by it 4 to grant. This shows that the spring travel limiter 6 one in the area of a free end section 11 of the base body 7 in this arranged sensor unit 12 having. The sensor unit shown here 12 may consist of a single or - as shown here - of two arranged in a common plane parallel to the transverse direction y extending individual sensors 13a . 13b put together. The sensor unit 12 is designed to prevent any compression of the base body 7 to monitor in its longitudinal direction x. Such compression occurs when the possible spring travel A of the semi-active damping means 2 by immersing the piston rod 3 in the cylinder tube 4 so far exploited that the free end section 11 of the travel limit limiter 6 with the front side 8th of the cylinder tube 3 comes into contact.

2 is an alternative embodiment of Federwegbegrenzers 6 refer to. As can be seen, the sensor unit here comprises a multiplicity of sensors 13a . 13b ; 14a . 14b ; 15a . 15b ; 16a . 16b , which in each case in pairs in different levels within the base body 7 are arranged.

As already indicated, the sensor unit 11 also in principle only a single of the indicated sensors 13a . 13b ; 14a . 14b ; 15a . 15b ; 16a . 16b include, so that in the 1 and 2 contained reference numerals 13a . 13b ; 14a . 14b ; 15a . 15b ; 16a . 16b Rather, they are to be understood only as possible location positions for this purpose.

LIST OF REFERENCE NUMBERS

1

 damper unit

2

Damping agent of 1

3

Cylinder tube of 2

4

Piston rod of 2

5

Storage for 4

6

Spring travel limiters from 1

7

Base body of 6 ;

7a

cylindrical base element of 6

8th

Front side of 3

9

outer surface of 7

10

inner lateral surface of 7

11

free end section of 7

12

Sensor unit of 6

13a

Sensor from 12 or possible location in 7

13b

Sensor from 12 or possible location in 7

14a

Sensor from 12 or possible location in 7

14b

Sensor from 12 or possible location in 7

15a

Sensor from 12 or possible location in 7

15b

Sensor from 12 or possible location in 7

16a

Sensor from 12 or possible location in 7

16b

Sensor from 12 or possible location in 7

A

Travel of 2

b

Thickness of the wall of 7

x

Longitudinal direction of 7

y

Transverse direction of 7

z

Depth direction of 7

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 5088760A [0006]
• DE 4021909 A1 [0006]
• US 5390121 A [0007]
• US 2004/0254701 A [0008]
• US 7672766 B2 [0009]
• US 6847874 B2 [0010]
• US 5467280A [0011]

Claims (9)

Damper unit for a suspension system of a vehicle, comprising a semiactive damping means ( 2 ) and a spring travel limiter ( 6 ) with an at least partially elastically formed base body ( 7 ), wherein the damping means ( 2 ) a cylinder tube ( 3 ) and one in the cylinder tube ( 3 ) linearly displaceably mounted piston rod ( 4 ), which at least partially by the Federwegbegrenzer ( 6 ), characterized in that the base body ( 7 ) at least one sensor unit ( 12 ), wherein the sensor unit ( 12 ) is adapted to a compression of the base body ( 7 ) in its longitudinal direction (x). Damper unit according to claim 1, characterized by at least two-stage tunability of the damping means ( 2 ), which allows at least a switch between a soft vote and a hard vote. Damper unit according to one of the preceding claims, characterized in that the sensor unit ( 12 ) in or at a free end portion ( 11 ) of the base body ( 7 ) is arranged, wherein the end portion ( 11 ) is provided, starting from a predetermined immersion depth of the piston rod ( 4 ) in the cylinder tube ( 3 ) of the damping agent ( 2 ) with the cylinder tube ( 3 ) to get in touch. Damper unit according to one of the preceding claims, characterized in that the sensor unit ( 12 ) at least two individual sensors ( 13a . 13b ), which in the longitudinal direction (x) of the base body ( 7 ) seen at a predetermined position in or on the base body ( 7 ) are arranged. Damper unit according to one of the preceding claims, characterized in that the sensor unit ( 12 ) at least two individual sensors ( 13a . 13b ; 14a . 14b ; 15a . 15b ; 16a . 16b ), wherein the individual sensors ( 13a . 13b ; 14a . 14b ; 15a . 15b ; 16a . 16b ) in the longitudinal direction (x) of the base body ( 7 ) successively in or on the base body ( 7 ) are arranged. Damper unit according to one of the preceding claims, characterized in that the base body ( 7 ) an opposite its longitudinal direction (x) inclined outer lateral surface ( 9 ) and a parallel to the longitudinal direction (x) extending inner circumferential surface ( 10 ), wherein the thus changing thickness (b) of a wall of the base body ( 7 ) is adapted to a progressive compression behavior of the base body ( 7 ) to obtain. Method for operating a semi-active damping device ( 2 ) with a spring travel limiter ( 6 ) having damper unit ( 1 ) for a suspension system of a vehicle, in particular according to one of the preceding claims, wherein the damping means ( 2 ) is switched at least between a soft vote and a hard vote, characterized in that the Federwegbegrenzer ( 6 ) an at least partially elastic base body ( 7 ) with at least one in or on the base body ( 7 ) arranged sensor unit ( 12 ), wherein the switching in the tuning of the damping means ( 2 ) based on a through the sensor unit ( 12 ) recorded and / or measured compression of the base body ( 7 ) is carried out. A method according to claim 7, characterized in that the switching in the vote of the damping means ( 2 ) on the basis of exceeding a threshold value for the width and / or speed of the compression of the base body ( 7 ) is carried out. A method according to claim 7 or 8, characterized in that the switching in the vote of the damping means ( 2 ) on the basis of exceeding a threshold value for the width and / or speed of the compression of the base body ( 7 ) is performed for a predetermined period of time.

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