Active spring unit

Abstract

The invention relates to an active spring unit (1) for elastically mounting a wheel suspension element (35) relative to a vehicle body (30). In order to provide an optimized active wheel suspension designed for fast and slow adjustment, the active spring unit (1) according to the invention has a spring element (2) which is mounted on the vehicle body (30) and has a torsion section (3) which extends along a torsion axis (B) from a wheel region (3.1) to a main transmission region (3.3), the self-locking secondary actuator unit (20) has a torsion part (3) which is torque-transmittably connected to the wheel suspension element (35) in the wheel region (3.1) and which is torque-transmittably connected to the self-locking primary actuator unit (10) in the primary transmission region (3.3), the non-self-locking secondary actuator unit (20) being at least indirectly torque-transmittably connected to the wheel region (3.1) at least partially bypassing the torsion part (3).

Description

Technical Field

[0001] The invention relates to an active spring unit. Background Art

[0002] In the wheel suspensions of modern motor vehicles, various elements are used to improve driving behavior and driving comfort. On the one hand, passive elements are used, namely springs and shock absorbers. These make it possible for the wheel carrier and the vehicle wheel arranged thereon to deflect relative to the vehicle body, with the springs temporarily storing energy and the shock absorbers dissipating energy in order to dampen vibrations. Furthermore, it is also known to use active elements, whose behavior is not limited to elastic energy storage or energy dissipation. Such active elements can be driven in order to apply a variable force between the wheel carrier and the vehicle body. Accordingly, these elements can also introduce energy, for example by actively raising the vehicle body. These active elements, which can also be referred to as spring actuators or suspension actuators, are usually combined with passive elements, in particular with springs.

[0003] For such active spring units or spring-damper units, there are various technical challenges. Active spring actuators have to meet conflicting requirements: requirements resulting from short ride height control operations with high adjustment speeds, e.g. to improve driving comfort or handling, and requirements resulting from ride height control operations with low adjustment speeds, e.g. to facilitate entry and exit or to reduce air resistance. Both applications require different actuators, which are arranged at different points in the suspension structure. High-speed actuators must be arranged parallel to the springs in terms of force flow, otherwise the springs would act as low-pass filters. In addition, the actuators would always be subject to the weight of the vehicle, which would result in high energy consumption. Low-speed actuators must be arranged in series with the vehicle's springs, otherwise they would limit the spring travel of the wheels and would preload the springs.

[0004] In particular, hydraulic actuators or electric actuators can be used, both systems having certain disadvantages. Hydraulic actuators require a centralized fluid system with a hydraulic tank, a pump and a plurality of hydraulic lines which must be laid throughout the vehicle. This results in an expensive and complex vehicle assembly process. Electric actuators operating at low voltage (<48V) require considerable current in order to function optimally. For a power requirement of 2 to 5 kW per wheel (that is, a total of 8 to 20 kW for the entire vehicle), a maximum current of 160-410 A is required.

[0005] KR 10 2016 0 081 047 A discloses an active suspension system for a vehicle, the active suspension having a reduction gear, a static load holding device and a rotation detection sensor. The reduction gear increases the torque of the electric motor and reduces the rotation speed. The static load holding device has a rotation center corresponding to the rotation axis of the electric motor and transmits the movement of the reduction gear to the vehicle wheels. The transmission is performed through a hydro-pneumatic spring device. The rotation detection sensor calculates the rotation angle about the rotation axis of the static load holding device and transmits the rotation angle to a controller.

[0006] WO 2010 / 105 721 A1 proposes an active electromechanical suspension system for the chassis of a motor vehicle having a first axle and a second axle, each for two oppositely disposed wheels. In this case, the first axle is assigned a spring strut with a spring strut actuator to each oppositely disposed wheel, and the second axle is assigned an active spring unit with a rotary actuator to each oppositely disposed wheel.

[0007] WO 2021 / 240 415 A1 proposes a vehicle with a suspension system, which connects a wheel carrier to a vehicle frame and has a suspension arm and a spring element. An electromechanical rotary drive element is arranged on the vehicle frame and has an electric motor and a reduction transmission device, which has at least one reduction part, and the reduction part accordingly has an output shaft, the rotation axis of the output shaft extending parallel to the axis of the joint connecting the suspension arm to the vehicle frame. The rod device is designed to transmit movement from the reduction part to the suspension arm via the output shaft. The sensor device is configured to detect parameters indicating the movement of the suspension arm, and the electronic control unit is configured to control the torque and angular position of the electric motor according to the signal transmitted by the sensor device.

[0008] US 8 511 697 B2 discloses an arrangement of a two-part stabilizer on a wheel suspension system of a motor vehicle, the stabilizer having torsion bars separated from one another, which are in each case articulated via an output rod to a wheel suspension element and can be rotated in the same direction or in opposite directions to one another via a respectively associated drive device, wherein each torsion bar is extended by a hollow shaft to increase its effective torsional length, the hollow shaft surrounds the torsion bar and forms a drive rod on the hollow shaft, wherein the torsion bar is mounted on a fixed bearing of the drive device and on an axial non-locating bearing of the hollow shaft.

[0009] DE 102 42 552 B4 proposes a device for electromechanically adjusting a two-part stabilizer in the chassis of a vehicle, in particular a motor vehicle, which device has an electric motor and has an adjusting gear, which is designed as a planetary gear differential and has at least one input element driven by the electric motor, two output elements acting on the two halves of the stabilizer, and at least two balancing elements which connect the output elements to one another in terms of drive. In this case, a planetary carrier is provided as an input element, the axially spaced and connected planetary gears of the planetary carrier mesh with a sun gear as an output element as balancing elements, wherein the number of teeth of the sun gear and the planetary gears is unequal, and the electric motor is fixed to the motor vehicle body.

[0010] EP 2 322 366 B1 discloses an arrangement of a two-part stabilizer on a wheel suspension system of a motor vehicle, wherein each stabilizer part has at least one torsion bar, which is articulated on a wheel suspension element via an output rod and can be rotated by a motor transmission unit, wherein the transmission part is connected between a transmission of the motor transmission unit and the torsion bar and allows an axially parallel arrangement of the motor / transmission unit and the torsion bar, wherein the torsion bar is oriented essentially at right angles to the transverse direction of the vehicle.

[0011] DE 10 2011 106 246 A1 has disclosed a drive device for a wheel suspension system of a motor vehicle, the drive device having at least one electric motor, by means of which a torsion bar acting on a wheel control element of the wheel suspension system can be preloaded via a reduction gear with the aid of the electric motor, wherein the electric motor is arranged at a radial distance from the torsion bar. Here, the electric motor outputs a transmission to the reduction gear via an intermediate gear, and the reduction gear is arranged coaxially with respect to the torsion bar.

[0012] In view of the prior art highlighted, there is still potential for improvement in providing active wheel suspensions designed for both fast and slow speed adjustments. Summary of the invention

[0013] The object of the present invention is to provide an active spring unit which is designed for fast and slow adjustment, that is to say an optimized active wheel suspension system.

[0014] According to the invention, this object is achieved by an active spring unit having the features of claim 1 , wherein the dependent claims relate to advantageous developments of the invention.

[0015] It is noted that the features and measures described in detail individually in the following description can be combined with one another in any technically meaningful way and reveal further developments of the invention. The description particularly additionally characterizes and explains the invention in detail together with the drawings.

[0016] The invention provides an active spring unit for elastically mounting a wheel suspension element relative to a vehicle body. An active spring unit is an active spring unit for a vehicle, more specifically for a wheel suspension system of a vehicle. The active spring unit can be used for motor vehicles such as trucks or passenger cars, but also for trailers without a dedicated drive, for example. The active spring unit can be part of a wheel suspension system of a vehicle, but can also have elements which strictly speaking do not belong to the wheel suspension system. The active spring unit serves to elastically mount a wheel suspension element on a vehicle body, or to elastically connect a wheel suspension element to a vehicle body, while allowing not only passive elastic mounting of the wheel suspension element but also active elastic mounting of the wheel suspension element, or actively influencing the position of the wheel suspension element. Active damping is also possible. In this context, "vehicle body" is used as a collective term for the frame, chassis and any subframes of the vehicle in question, that is to say those parts which usually form the sprung mass. The wheel suspension element is usually deflectable relative to the vehicle body at least along the vehicle vertical axis (Z axis). Furthermore, a deflection partially along the vehicle longitudinal axis (X axis) and / or along the vehicle transverse axis (Y axis) is also possible. The wheel suspension element can in particular be a link, such as a longitudinal link, a transverse link or a semi-trailing link, which in the assembled state is correspondingly connected to a wheel carrier on which the vehicle wheel is rotatably mounted. However, the wheel suspension element can also be the wheel carrier itself, for example.

[0017] The active spring unit has a spring element, which is mounted on the vehicle body and has a torsion portion extending along the torsion axis. The spring element or at least its torsion portion can also be referred to as a torsion spring, torsion spring element or torsion element. The torsion portion extends along the torsion axis, which can also form an axis of symmetry for the torsion portion. The torsion portion is designed to elastically deform under the action of a torque acting around the torsion axis and thus absorb and store energy. In this case, the torsion portion produces an opposite torque. In principle, different materials can be used for the spring element and / or the torsion portion, as long as these materials have sufficient elastic properties and are also sufficiently durable to be used as part of the wheel suspension system. In particular, spring steel and composite materials, in particular fiber composite materials, can be used as materials. Such fiber composite materials have fibers such as glass fibers, carbon fibers and / or aramid fibers for reinforcement purposes, which are embedded in a polymer matrix (e.g., a plastic or a synthetic resin matrix composed of epoxy resin, etc.). Optionally, other particles, layers or components that cannot be classified as polymers or classified as fibers here can be embedded in the matrix or deposited on the matrix. Different materials can also be used for different parts of the spring element. The spring element is mounted on the vehicle body so as not to be able to move arbitrarily relative to the vehicle body. However, the spring element can be connected to the vehicle body via one or more bearings so that at least the torsion of the torsion part is possible.

[0018] The torsion section extends along the torsion axis from the wheel region, in which the torsion section is torque-transmittantly connected to the wheel suspension element, to the main transmission region, in which the torsion section is torque-transmittantly connected to the self-locking main actuator unit. The wheel region and the main transmission region are sub-regions of the torsion section, more specifically the end regions of the torsion section. However, as will become clearer below: these do not have to be the end portions of the spring element; rather, the spring element can extend outside the wheel region or outside the main transmission region. In the wheel region, the torsion section is torque-transmittantly connected to the wheel suspension element. In the assembled state, the torsion section is torque-transmittantly connected to the wheel suspension element. Here and below, in the absence of explicit reference to other references, the torque transmission is always related to the torsion axis. The active spring unit is therefore designed so that it is possible to transmit torque between the wheel region and the wheel suspension element. Therefore, the torque in the torsion section can generate a force on the wheel suspension element, and the wheel suspension element can equally exert a force that causes the torque.

[0019] The torsion section is connected to the main actuator unit in a torque-transmitting manner in the main transmission region, i.e. the main actuator unit can exert a torque on the main transmission region, wherein an opposite torque and a corresponding force can react on the main actuator unit. The term "main actuator unit" indicates that it has at least one main actuator. The main actuator unit can exert a torque which can lead to a rotation of the main transmission region relative to the vehicle body. Here, the main actuator unit is of self-locking design, i.e. it can drive the main transmission region itself, i.e. put the main transmission region into motion, but, conversely, a torque in the main transmission region cannot lead to an adjustment of the main actuator unit. The position of the main transmission region is therefore determined by the main actuator unit. Thus, the torque of the torsion section between the wheel region and the main transmission region can be influenced, which in turn leads to a change in the static position of the wheel suspension element. For example, a force exerted on the torsion section by the wheel suspension element leads to a torque, but this torque cannot adjust the main actuator unit because the main actuator unit is of self-locking design.

[0020] Here, the non-self-locking secondary actuator unit at least partially bypasses the torsion section and is at least indirectly connected to the wheel area in a torque-transmitting manner. The name "secondary actuator unit" accordingly indicates that it has at least one secondary actuator. The secondary actuator unit is at least indirectly connected to the wheel area in a torque-transmitting manner. That is, there may be a direct connection between the secondary actuator unit and the wheel area, but an indirect connection may also be provided by another element or by a part of the torsion section. In any case, the connection has a torque-transmitting effect, so that the secondary actuator unit can transmit torque to the wheel area. However, compared to the main actuator unit, the secondary actuator unit is of non-self-locking design. Therefore, the torque that reacts on the secondary actuator unit can lead to the adjustment of the secondary actuator unit. On the other hand, the secondary actuator unit can actively generate a torque in the wheel area, which torque correspondingly leads to a force acting on the wheel suspension element. Regardless of whether the connection to the wheel area is direct or indirect, the connection at least partially bypasses the torsion section. Therefore, the connection is provided at most by a part of the torsion section, and in some cases it is even completely independent of the torsion section. This means that the force flow between the secondary actuator unit and the wheel region passes at most through a part of the torsion component, but bypasses another part of the torsion component or even the entire torsion component.

[0021] The active spring unit according to the invention allows two independent active manipulations of the forces acting on the wheel suspension elements. Here, relatively slow changes are provided by the main actuator unit. This adjusts the overall preload of the torsion section via the main transmission area, so to speak. In this way, for example, an overall harder or softer spring characteristic can be set, or the vehicle body can be raised or lowered relative to the chassis. Since the main actuator unit is self-locking, the preload cannot be changed without actively adjusting the main actuator unit. On the other hand, the torsion section allows elastic movements of the wheel area relative to the main transmission area. With regard to the force flow, the main actuator unit is arranged in series with the torsion section, which acts as a passive spring. In contrast, the secondary actuator unit provides for rapid short-term changes in the forces acting on the wheel suspension elements. This secondary actuator unit can act as both a spring and a damper, that is, it can prevent undesirable vibration behavior. Due to the at least partial bypassing of the torsion section, the connection to the wheel area is more direct and, so to speak, "harder". As a result, the short-term adjustment by the secondary actuator unit has a more direct effect on the wheel suspension elements. On the other hand, the secondary actuator unit is of non-self-locking design, so that when switched to the passive state, the secondary actuator unit can follow the movement of the torsion section. In this state, the dynamic behavior of the wheel suspension element is mainly determined by the torsion section and the primary actuator unit. Since the connection between the secondary actuator unit and the wheel region at least partially bypasses the torsion section, it can be said that the secondary actuator unit is arranged in parallel with at least a part of the torsion section in terms of the force flow. The torsion section therefore also cannot act as a low-pass filter between the secondary actuator unit and the wheel region or the wheel suspension element to any relevant extent.

[0022] Advantageously, the main actuator unit has a main actuator and a self-locking main transmission, the main actuator being connected to the main transmission region via the self-locking main transmission. That is, the self-locking main actuator unit is positioned on the main transmission. The main transmission can be directly connected to the main transmission region. Advantageously, the secondary actuator unit also has a secondary actuator and a non-self-locking secondary transmission, the secondary actuator being at least indirectly connected to the wheel region via the non-self-locking secondary transmission. The secondary transmission is therefore designed such that it can be driven via an input connected to the secondary actuator and via an output at least indirectly connected to the wheel region. Preferably, both the main actuator and the secondary actuator are designed as rotary actuators.

[0023] Although it is possible to realize the above configuration using hydraulic actuators or other actuators, for example, it is particularly preferred that at least one actuator is designed as an electric motor that can be operated at a voltage of at least 48 V, but preferably higher. The use of an electric motor leads to a simplification of the design, since only power supply lines and possibly control lines are required to operate the actuator. For example, another advantage is that the secondary actuator can act as a generator and can recover energy introduced into the active spring unit by the dynamic movement of the wheel suspension element. The use of an electric motor operating at high voltage means that the power level required during operation can be achieved with a lower current intensity. Therefore, the power supply line can have a smaller cross-section without the risk of excessive power loss. This configuration is particularly suitable for electric vehicles, because in these electric vehicles, high voltages are easily available from the vehicle battery or possibly from a fuel cell.

[0024] There are various possibilities for the configuration of the main transmission. For example, the main transmission can be designed as a worm gear with a worm shaft connected to the main actuator and a worm gear rotatably connected to the main transmission area. Another possibility is that the main transmission is designed as a spindle drive mechanism with a threaded spindle connected to the main actuator and with a spindle nut interacting with a main arm, which is rotatably connected to the main transmission area and extends at an angle to the torsion axis. The main arm can extend in particular at right angles to the torsion axis. The main arm can be formed integrally with the torsion part as part of the spring element.

[0025] One embodiment provides a secondary actuator which is connected in a motion-transmitting manner to a first gear (Getrieberad), which is offset laterally relative to the torsion axis and is connected in a motion-transmitting manner to a second gear, which is coaxial with the torsion axis. When the secondary actuator is operated, the secondary actuator drives the first gear, which in turn drives the second gear. Each gear can be designed in particular as a gear, for example as a spur gear. The two gears can interact with each other directly or through at least one insertion element. In particular, the first gear can interact with the second gear via a closed, flexible transmission element. For example, the transmission element can be a toothed belt, but for example a chain or a V-belt is also conceivable. The circumference of the first gear or the number of teeth can be smaller than the circumference of the second gear or the number of teeth, so that a reduction ratio is obtained.

[0026] In one embodiment, the secondary transmission has a reduction gear, which surrounds the torsion axis. The reduction gear is used to convert the movement of the secondary actuator into a simplified movement, so that even in the case of relatively large movements of the secondary actuator, fine steering of the wheel area can be achieved. In addition, the torque of the secondary actuator can be increased in this way. The reduction gear surrounds the torsion axis and can, for example, be centered at least partially around the torsion axis. The reduction gear can have at least one gear centered about the torsion axis. For example, the reduction gear can be designed as a planetary gear, but is preferably designed as a cycloidal gear. This embodiment can be combined with the above-mentioned embodiment, in which the second gear is connected to the reduction gear or is part of the reduction gear. The reduction ratio of the above-mentioned two gears can be combined with the reduction ratio of the reduction gear and thus increased.

[0027] As already mentioned, the secondary actuator unit can be connected directly to the wheel area. However, in some cases, it may be advantageous to provide an elastic connection to the wheel area. One possibility in this regard is that the secondary actuator unit is connected to the torsion portion in a secondary transmission area arranged between the wheel area and the main transmission area, and is therefore connected to the wheel area via a part of the torsion portion. That is to say, the secondary actuator unit has a direct connection to the torsion portion, not in the wheel area but between the wheel area and the main transmission area. Preferably, the corresponding secondary transmission area is arranged closer to the wheel area than the main transmission area. In particular, the secondary transmission device can be connected to the torsion portion in the secondary transmission area. The connection to the wheel area is achieved via that part of the torsion portion arranged between the wheel area and the secondary transmission area. Preferably, this part can constitute at most 50% or at most 30% of the torsion portion.

[0028] Another possibility is that the secondary actuator unit is connected to the wheel region by a secondary torsion element bypassing the torsion section. Like the torsion section, the secondary torsion element is elastically deformable. The torsion section can consist of a material that is also suitable for the torsion section. In particular, the secondary torsion element can absorb energy by torsion around the torsion axis. The secondary torsion element can be manufactured separately from the spring element and connected to the spring element in the wheel region. However, the secondary torsion element can also be manufactured integrally with the spring element. For example, the secondary torsion element can be arranged as an extension of the torsion section on the wheel region side opposite the torsion section. In some cases, the secondary torsion element and the torsion section can directly transition to each other. Another possibility is that the secondary torsion element radially surrounds the torsion section or a part thereof on the outside relative to the torsion axis. Here, the secondary torsion element forms a hollow profile, and the torsion section or a part thereof is arranged in the hollow profile. It can also be said that the torsion section and the secondary torsion element are arranged around each other. In any case, the secondary torsion element bypasses (preferably completely bypasses) the torsion section.

[0029] In one embodiment, in the wheel region, the torsion section is rotatably connected to a wheel rod which interacts with the wheel suspension element in a motion-transmitting manner. The wheel rod can be formed integrally with the torsion section, that is to say can be part of the spring element. However, a separately manufactured wheel rod which is connected to the torsion section in a form-fitting, frictional and / or integrally bonded manner would also be possible. Another possibility is that in the wheel region, the torsion section is rotatably connected to the wheel suspension element, wherein the torsion axis coincides with the pivot axis of the wheel suspension element. In this case, the wheel suspension element is typically a wheel link, such as a transverse link or a longitudinal link. Due to the rotatable connection to the wheel suspension element, a pivoting of the wheel suspension element about the pivot axis directly results in a rotation of the wheel region and therefore typically results in a torsion of the torsion section.

[0030] The direction of the torsion axis in the vehicle, that is to say the direction of the torsion axis relative to the longitudinal axis (X axis) of the vehicle, the transverse axis (Y axis) of the vehicle and the vertical axis (Z axis) of the vehicle, can be selected differently. The torsion axis is usually arranged in a horizontal plane (XY plane), but can also be inclined in the direction of the vertical axis (Z axis). Different directions relative to the XY plane can be selected. For example, the torsion axis can extend at least partially along the longitudinal axis of the vehicle. The torsion axis can extend parallel to the longitudinal axis of the vehicle or enclose a small angle of, for example, up to 30° with the longitudinal axis of the vehicle. In another preferred embodiment, the torsion axis extends at least partially along the transverse axis of the vehicle, but does not necessarily extend parallel to the transverse axis of the vehicle. The torsion axis can also enclose an angle of, for example, up to 30° with the transverse direction of the vehicle.

[0031] Since the axle of a vehicle usually has two wheels arranged on both sides of the vehicle body, one possibility is to provide an active spring unit for each of the two wheels, wherein the two active spring units can be configured mirror-symmetrically. In another variant, one active spring unit can be used for the active elastic mounting of both wheels. Here, the spring element has two torsion sections, which extend along the torsion axis from each wheel area to the main transmission area, in which a specific torsion section can be connected to the wheel suspension element in a torque-transmitting manner, wherein each secondary actuator unit is at least partially bypassing the two torsion sections and is at least indirectly torque-transmittingly connected to the associated wheel area. Preferably, the two torsion sections are rotatably connected to each other and are also preferably formed integrally with each other. In any case, the two torsion elements are connected to a (single) main actuator in the main transmission area. The main actuator unit can thus cause or manipulate the simultaneous torsion of the two torsion sections. In contrast, a dedicated secondary actuator unit is provided for each torsion section. This means that with respect to the short-term application of force, it is possible to independently manipulate the wheel suspension elements on both sides. In contrast, for quasi-steady state (that is to say long-term manipulation), the same load is applied to both sides by the main actuator unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Further advantageous details and effects of the invention will be discussed in more detail below based on exemplary embodiments illustrated in the drawings, in which: Figure 1 is a schematic plan view of a first embodiment of an active spring unit according to the present invention; Figure 2 is a schematic plan view of a second embodiment of an active spring unit according to the present invention; Figure 3 is a schematic plan view of a third embodiment of an active spring unit according to the present invention; Figure 4 is a schematic plan view of a fourth embodiment of an active spring unit according to the present invention; Figure 5 is a schematic plan view of a fifth embodiment of an active spring unit according to the present invention; and Figure 6 is a schematic plan view of a sixth embodiment of an active spring unit according to the present invention. DETAILED DESCRIPTION

[0033] In the different figures, identical parts are always denoted by the same reference numerals, for which reason these parts will generally also be described only once.

[0034] Figure 1A first embodiment of an active spring unit 1 according to the invention is shown, which can be provided, for example, for an electric vehicle. A wheel suspension element 35, in this case a transverse link, is mounted on a vehicle body 30 so as to be pivotable about a pivot axis C, which extends parallel to the vehicle longitudinal axis X. The wheel suspension element 35—optionally together with other elements not shown here—movably connects a wheel carrier 36 to the vehicle body 30, such that the wheel carrier can be moved at least partially along a vehicle vertical axis Z extending perpendicularly to the drawing plane. A vehicle wheel 37 is mounted on the wheel carrier 36 so as to be pivotable about an axis of rotation A. The spring element 2, which can be formed, for example, from spring steel, has a torsion section 3 mounted on the vehicle body 30 via a pivot bearing 31. The spring element extends along a torsion axis B, which extends parallel to the vehicle transverse axis Y. The torsion section 3 has a wheel region 3.1 at one end, from which a wheel rod 4 formed integrally with the torsion section 3 extends to the wheel suspension element 35. The deflection of the wheel suspension element 35 and the rotation of the wheel region 3 . 1 about the torsion axis B are coupled to one another via the wheel lever 4 .

[0035] The torsion section 3 has at the other end a main transmission region 3.3, in which the torsion section is connected to a main actuator unit 10. The main actuator unit has a main actuator 11 in the form of an electric motor, which drives a worm shaft 13 of a main transmission 12. The worm shaft 13 interacts with a worm gear 14 which is rotatably connected to the main transmission region 3.3. Since the main transmission 12 is of self-locking design, operation of the main actuator 11 can cause a rotation of the main transmission region 3.3 about the torsion axis B, whereas, conversely, a torque acting on the torsion section 3 cannot cause an adjustment of the main transmission 12 or the main actuator 11. The main actuator 11 is provided for generating a preload torque in the torsion section 3, which preload torque changes only relatively little and / or only slowly. Therefore, the application of load to the main suspension element 35 by the main actuator 11 can be referred to as slowly changing or as being in a quasi-steady state.

[0036] Between the wheel area 3.1 and the main transmission area 3.3, the torsion section 3 has a secondary transmission area 3.2, in which the torsion section is connected to a secondary actuator unit 20. The secondary actuator unit 20 has a secondary actuator 21, which is also an electric motor. Like the main actuator 11, the secondary actuator is powered by a voltage source 40 (for example, a battery unit of an electric vehicle), which delivers a voltage V, which can be a high voltage of at least 48 V. Therefore, the operation of the actuators 11, 21 only requires relatively moderate currents, and even in the case of relatively small conductor cross-sections, the actuators 11, 21 accordingly only cause limited resistance losses.

[0037] The secondary actuator 21 drives the first gear 23 of the secondary transmission 22, which is a spur gear. The first gear 23 is drivingly connected to the second gear 24 via a toothed belt 25, which is also a spur gear and coaxial with the torsion part 3. The second gear 24 is larger and has a greater number of teeth than the first gear 23, so that the movement of the secondary actuator 21 passes through a reduction ratio. The reduction ratio is further increased by a reduction gear 26, which is around the torsion axis B and can be designed as a cycloidal transmission, for example. The reduction gear 26 is driven by the second gear 24 and is rotatably connected to the torsion part 3 in the secondary transmission area 3.2. The operation of the secondary actuator 21 can cause a rotation of the secondary transmission area 3.2 via the secondary transmission 22, so that the torque is transmitted to the wheel area 3.1 via a part of the torsion part 3, and the wheel area 3.1 accordingly causes a change in the force acting on the wheel suspension element 35. The secondary actuator 21 is provided for causing a short-term change in the force acting on the wheel suspension element 35. This can also be called dynamic operation. This is possible, in particular, because the distance between the secondary transmission area 3.2 and the wheel area 3.1 is only approximately equal to 30% of the length of the torsion section 3. That is, the torsion section 3 is mainly bypassed and therefore cannot act as a low-pass filter to a large extent. On the other hand, due to the non-self-locking design of the secondary transmission, the secondary actuator 21 can also be operated as a generator, wherein the movement of the wheel suspension element 35 drives the secondary actuator 21 via the wheel rod 4, a part of the torsion section 3 and the secondary transmission 22. In this way, the secondary actuator 21 can recover energy, which can be stored in the voltage source 40 accordingly.

[0038] Figure 2 A second embodiment of the active spring unit 1 according to the invention is shown, which corresponds essentially to the first embodiment and will not be discussed again in this respect. For the sake of clarity, the voltage source 40 has been omitted here and in the other figures. In this embodiment, the main arm 5 is integrally connected to the main transmission area 3.3 of the torsion part 3. This main arm is connected in a manner that is not explained in detail here to the spindle nut 16 of the main transmission 12, which in this case adopts a spindle transmission mechanism. The spindle nut 16 is located on a threaded spindle 15, which is driven by the main actuator 11. The main transmission 12 of this design is also self-locking.

[0039] Figure 3An embodiment is shown in which the spring element 2 is extended beyond the wheel region 3.1 with a secondary torsion element 6. The secondary transmission 22 designed as in the first and second embodiments interacts with the secondary torsion element 6. In this case too, the secondary transmission unit 20 is connected to the transmission region 3.1 with limited elasticity, wherein in this case the torsion part 3 is completely bypassed with respect to the force flow. Here, and Figure 4 In the diagram, the wheel suspension element 35 , the wheel carrier 36 and the vehicle wheel 37 have been omitted.

[0040] Figure 4 A fourth embodiment is shown with a secondary torsion element 6 in the form of a hollow profile, which surrounds a portion of the torsion section 3. In this embodiment as well, the secondary actuator unit 20 is connected to the wheel region 3.1, bypassing the torsion section 3 completely.

[0041] Figure 5 A fifth embodiment is shown, which corresponds essentially to the first embodiment. In this case, however, the torsion section 3 is oriented parallel to the vehicle longitudinal axis X. The spring element 2 also does not have a wheel rod 4, but is rotatably connected directly to the wheel suspension element 35. The torsion axis B and the pivot axis C of the wheel suspension element 35 coincide. The pivoting movement about the pivot axis C is therefore directly coupled to the rotation of the wheel region 3.1 about the torsion axis B.

[0042] Figure 6 A sixth embodiment is shown in which the active spring unit 1 is designed for the active elastic mounting of two vehicle wheels 37. Here, the spring element 2 extends to both sides of the primary transmission region 3.3, in the two torsion sections 3, to two edge regions 3.1 arranged on both sides of the vehicle body 30, with respect to the vehicle transverse axis Y. Two secondary actuator units 20, which are structurally identical in principle but mirror-symmetrical with respect to one another, interact with the torsion section 3 via two secondary transmission regions 3.2, which are likewise arranged symmetrically on the spring element 2.

[0043] List of reference numerals: 1 Active spring unit 2 Spring element 3. Twist part 3.1 Wheel area 3.2 Secondary transmission area 3.3 Main transmission area 4 wheel rod 5 Main rod 6 Secondary torsion element 10 Main actuator unit 11 Main actuator 12 Main transmission 13 Worm shaft 14 Worm gear 15 thread spindle 16 Spindle nut 20 secondary actuator units 21 Secondary actuator 22 Secondary transmission 23, 24 gears 25 toothed belt 26 Reduction gear 30 Vehicle body 31 Pivot bearing 35 wheel suspension elements 36 wheel rack 37 Vehicle wheels 40 Voltage Source ARotation axis B Torsion axis C Pivot Axis V Voltage XX axis YY axis ZZ axis

Claims

1. An active spring unit (1) for elastically mounting a wheel suspension element (35) relative to a vehicle body (30), the active spring unit comprising a spring element (2) mounted on the vehicle body (30) and having a torsion section (3), the torsion section (3) extending along a torsion axis (B) from a wheel region (3.1) to a main transmission region (3.3), the torsion section being torque-transmittantly connected to the wheel suspension element (35) in the wheel region (3.1), the torsion section being torque-transmittantly connected to a self-locking primary actuator unit (10) in the main transmission region (3.3), wherein a non-self-locking secondary actuator unit (20) at least partially bypasses the torsion section (3) and is at least indirectly torque-transmittantly connected to the wheel region (3.1).

2. The active spring unit according to claim 1, It is characterized in that The main actuator unit (10) comprises a main actuator (11) and a self-locking main transmission (12), wherein the main actuator (11) is connected to the main transmission area (3.3) via the self-locking main transmission (12), and / or the secondary actuator unit (20) comprises a secondary actuator (21) and a non-self-locking secondary transmission (22), wherein the secondary actuator (21) is at least indirectly connected to the wheel area (3.1) via the non-self-locking secondary transmission (22).

3. Active spring unit according to any one of the preceding claims, It is characterized in that At least one actuator (11, 21) employs an electric motor, which is preferably operable at a high voltage (V) of at least 48V.

4. Active spring unit according to any one of the preceding claims, It is characterized in that The secondary actuator (21) is connected in a motion-transmitting manner to a first gear (23) which is laterally offset relative to the torsion axis (B) and is connected in a motion-transmitting manner to a second gear (24) which is coaxial with the torsion axis (B).

5. Active spring unit according to any one of the preceding claims, It is characterized in that The secondary transmission (22) has a reduction gear (26) which surrounds the torsion axis (B) and is preferably designed as a cycloidal gear.

6. Active spring unit according to any one of the preceding claims, It is characterized in that The secondary actuator unit (20) is connected to the torsion section (3) in a secondary transmission area (3.2) arranged between the wheel area (3.1) and the main transmission area (3.3), and is therefore connected to the wheel area (3.1) via a part of the torsion section (3).

7. Active spring unit according to any one of the preceding claims, It is characterized in that The secondary actuator unit (20) is connected to the wheel region (3.1) via a secondary torsion element (6) bypassing the torsion section (3).

8. Active spring unit according to any one of the preceding claims, It is characterized in that In the wheel region (3.1), the torsion section (3) is rotatably connected to a wheel lever (4) which interacts with the wheel suspension element (35) in a motion-transmitting manner, or the torsion section is rotatably connected to the wheel suspension element (35), wherein the torsion axis (B) coincides with a pivot axis (C) of the wheel suspension element (35).

9. Active spring unit according to any one of the preceding claims, It is characterized in that The torsion axis (B) extends at least partially along the vehicle longitudinal axis (X) and / or at least partially along the vehicle transverse axis (Y).

10. Active spring unit according to any one of the preceding claims, It is characterized in that The spring element (2) has two torsion sections (3), which extend along the torsion axis (B) from each wheel region (3.1) to the main transmission region (3.3), in which a particular torsion section (3) is torque-transmittably connected to the wheel suspension element (35), wherein each secondary actuator unit (20) at least partially bypasses the two torsion sections (3) and is at least indirectly torque-transmittably connected to the associated wheel region (3.1).

Images