AT524955B1 - Platform for at least four-wheel motor vehicles with electric drive - Google Patents

Abstract

In a platform for at least four-wheel motor vehicles with an electric drive, the right and left wheels (11) can be steered by at least one axle assembly (2) and are driven individually by a respective electric motor (15). The wheel carriers (12) of the right and left wheels (11) are coupled to one another via rod parts (28, 29) articulated on the wheel carriers (12) and an adjustable connecting unit (30) connecting the rod parts (28, 29). The wheels (11) are steered only by means of drive and/or braking forces. At least one actuator (31, 44, 47, 57) of the adjustable connection unit (30) covers the distance between the right and left connection points (30a, 30b) via which the connection unit (30) is connected to the respective rod part (28, 29). is actively adjustable or a change in the distance between the right and left connection points (30a, 30b) can be released and blocked.

Description

description

The invention relates to a platform for at least four-wheel motor vehicles with electric drive, having at least one front axle assembly forming a front axle and at least one rear axle assembly forming a rear axle, which are spaced apart from one another in a longitudinal direction of a supporting chassis of the platform and of which at least one of the axle assemblies has wheels that can be steered about respective pivot axes, which are mounted on wheel carriers that can pivot about the pivot axes so as to be rotatable about wheel axles, with the right and the left wheel of this axle assembly each being individually controlled by a respective electric motor with regard to rotation about the respective wheel axles are driven and for coupling the wheel carriers of the right and left wheels with respect to the pivot positions of these wheel carriers about the pivot axes on the right wheel carrier, a right rod part is articulated and on the left wheel carrier a left rod part is articulated, which is connected to the right Sta ngenteil is connected, wherein the steering of the wheels takes place only by means of driving and / or braking forces acting with respect to the rotation of the wheels about the wheel axles.

Platforms for four-wheel motor vehicles with electric drives are known in different embodiments.

Among other things, with regard to autonomous driving, with some areas of application with limited maximum speeds, for example in the range of up to 80 or 90 km/h, there are new requirements and possibilities, which have already led to new starting points.

So specially adapted for such applications platforms have been developed, which can be easily equipped with different structures to allow different purposes, such as passenger transport or load transport. Such platforms are also referred to as skateboard platforms.

In four-wheel motor vehicles with electric drives, the two steerable wheels of a front axle assembly forming a front axle being driven individually by means of wheel hub motors, it is already known to steer the wheels only by means of drive and/or braking forces. This emerges, for example, from DE 10 2019 104 391 A1 or WO 2020/169134 A1. The wheel carriers belonging to the front axle, which can be pivoted about pivot axes in order to steer the wheels, are connected to one another via a connecting rod which has rod parts connected to one another in an articulated manner. There is neither a part acting mechanically on the rod parts nor a separate steering actuator for steering the wheels. Rather, the motor vehicle is steered in that the individual wheel drives of the wheels arranged on the steerable axle are used to transmit drive and/or braking torques to these wheels, which steer the wheels in a predetermined direction. Braking torques for steering the wheels can be exerted instead or additionally by means of a mechanical braking device for the respective wheel. In the event that an individual wheel drive fails, there is a holding device which interacts with the rod parts connecting the wheel carriers in order to brake or block them.

A similar device also emerges from US Pat. No. 10,562,400 B2. The holding device, in order to be able to fix one of the steerable wheels in a given angular position, interacts here directly with the pivot bearing of the wheel carrier about the pivot axis.

In contrast, in the steering device known from US Pat. No. 9,221,495 B2, the wheels are steered by means of steering actuators, which actively adjust the angular position of a respective wheel carrier about the pivot axis. These steering actuators are available in addition to the electric individual wheel drives. The electric motors are arranged outside of the respective wheel and are connected to it via a drive shaft.

It is also known that the occurrence of vehicle instability under load changes or when braking on a roadway with different coefficients of friction for the left

and right wheels can be counteracted by the rear wheels being brought into toe-in when driving straight ahead or cornering. For this purpose, a device for adjusting the toe difference angle of the non-steered rear wheels is described in DE 10 2006 055 294 A1. For this purpose, a distance in the transverse direction of the vehicle between the pivot point of the wheel control arm and the wheel carrier is adjusted by means of an actuator. DE 10 2018 201 670 B4 discloses toe adjustment of a rear wheel by means of an actuator which acts on a control arm in the longitudinal direction of the vehicle.

The object of the invention is to provide a platform of the type mentioned in which advantageous driving characteristics are made possible. According to the invention, this is achieved by a platform with the features of claim 1.

In the platform according to the invention, the rod parts articulated to the wheel carriers are connected to one another via an adjustable connecting unit in order to enable adjustment of the toe difference angle between the right and left wheels. This is connected to the right rod part at a right connection point and to the left rod part at a left connection point. The connection unit has at least one actuator, by which the distance between the right and left connection point can be actively adjusted or by which a change in the distance between the right and left connection point can be enabled and blocked.

The invention provides an advantageous platform for a motor vehicle in which the wheels are steered only by means of drive and braking forces acting with respect to the rotation of the wheels about the wheel axles, with an adjustment of the toe difference angle, which at a specific steering angle of the Wheels is present while driving is enabled.

Thus, according to an advantageous method which uses the device according to the invention, the toe difference angle when driving through curves with different radii can be adapted to the respective curve radius by adjusting the connection unit. This enables optimal cornering.

According to a further advantageous method, which applies the device according to the invention, the toe difference angle can be adjusted so much that the vehicle is braked. This enables the vehicle to be braked while driving and/or a parking brake can be provided.

According to a further advantageous method, which uses the device according to the invention, in which both the front and rear wheels are designed to be steerable and their toe difference angle, which is present at a specific steering angle of the wheels, can be adjusted by means of an adjustable connection unit, the steering angles of the front and rear wheels adjusted so that all wheels are tangential to a common circular line. This enables the vehicle to rotate about an imaginary circle center located within the platform, preferably centrally located, ie turning on the spot.

Preferably, the toe difference angle between the right and left wheels of the at least one axle assembly with steerable wheels is adjustable by more than 5°, preferably more than 10°, particularly preferably more than 20° via the adjustable connection unit.

In the first variant of the invention, in which the distance between the right and left connection points of the connection unit can be actively adjusted by at least one actuator, this adjustment is advantageously supported in that the right and left wheels are activated by means of drive and /or braking forces, which act around the wheel axle, such different steering forces are exerted that they act in the direction of such pivoting of the wheel carriers of these wheels around the pivot axes, through which the toe difference angle to be set is achieved. As a result, only small actuating forces have to be exerted by the at least one actuator.

If the distance between the right and the left connection point of the connection unit is not adjusted by at least one actuator, the distance between the

Connection points are fixed and the movement of the left and right rod parts is synchronously (= simultaneously in the same direction and at the same speed) coupled via the connection unit.

In the second variant of the invention, in which a change in the distance between the right and left connection point can be released and blocked by at least one actuator, the toe difference angle can be changed in a release state of the connection unit by the right and left wheel are steered differently. This different steering of the wheels takes place only by means of driving and/or braking forces, which act around the respective wheel axle. In a locked state of the connection unit, the distance between the connection points is then fixed and the movement of the left and right rod parts is synchronously (= simultaneously in the same direction and at the same speed) coupled via the connection unit. A change in the toe difference angle (relative to a specific steering angle of the wheels) is thus blocked. The adjustment between the release state and the locked state of the connection unit is carried out by the at least one actuator.

In particular, driving and braking forces acting around the wheel axles can be exerted to steer the wheels with the individual wheel drives of the wheels. Instead or in addition, braking forces for steering the wheels can optionally also be exerted with mechanical braking devices for the wheels.

In one possible embodiment of the invention, the connection unit has a self-locking helical gear which can be driven by at least one actuator and by means of which the distance between the right and left connection point can be adjusted.

In a further possible embodiment, the connecting unit has two arms which are at an angle to one another and can be pivoted relative to one another about an axis and which each have one of the connecting points at a distance from the axis. The angle between the arms and thus the distance between the right and left connection points can be adjusted by at least one actuator, or the pivotability of the arms can be released and blocked by at least one actuator.

In a further possible embodiment, the connecting unit has at least one hydraulic piston-cylinder unit with a piston arranged in a cylinder which can be adjusted by at least one actuator or whose position in the cylinder can be released and blocked by at least one actuator.

Further advantages and details of the invention are explained below with reference to the accompanying drawing. In this show:

Figure 1 is an oblique view of an embodiment of a platform according to the invention;

Figure 2 is a side view;

Figure 3 is a bottom view;

[0027] FIG. 4 shows an exploded view of a front axle module (without the parts arranged on the left-hand wheel carrier in relation to the direction of travel);

[0028] FIG. 5 shows an oblique view (without the parts arranged on both wheel carriers);

Figure 6 is a plan view;

[0030] FIG. 7 shows a top view analogous to FIG. 6 with a different toe difference angle compared to FIG. 6;

Figure 8 is a front view;

Figure 9 is an exploded view of the connection unit;

Figure 10 shows a longitudinal center section through the connection unit;

[0034] FIGS. 11 and 12 differently set toe difference angles of the steerable front wheels when cornering with different radii;

[0035] FIGS. 13 and 14 show possible positions of the steerable front wheels for braking the vehicle;

[0036] FIG. 15 shows a highly schematic representation of an embodiment with steerable front and rear wheels, the steering angles of which are set tangentially to a common circular line;

Figures 16 to 18 are oblique, plan and front views of parts of an axle assembly according to a second embodiment of the invention;

19 to 21 representations analogous to FIGS. 16 to 18 according to a third exemplary embodiment of the invention;

21 to 24 representations analogous to FIGS. 16 to 18 according to a fourth embodiment of the invention.

For the sake of clarity, these are simplified, partially schematic illustrations.

A first exemplary embodiment of the invention is explained below with reference to FIGS. 1 to 10. The platform has a chassis 1 on which a front axle assembly 2 and a rear axle assembly 3 are carried. In the figures, the chassis 1 is only shown schematically as a contoured plate. In practice the chassis will have different parts, for example interconnected beams and/or plate parts. Preferably, accumulators for the electric drive are also attached to the chassis, which are not shown in the figures.

The wheels 11 at the front with respect to the direction of travel can be steered. The motor vehicle therefore has a steered front axle. The front axle assembly 2 includes the front. Wheels 11 together with their wheel suspension and forms the steered front axle, as described in more detail below.

The rear wheels 7 are not steerable in the embodiment. The rear axle assembly 3 includes the rear wheels 7 together with their wheel suspension and forms the rear axle.

In a further advantageous embodiment, the rear axle assembly 3 could have steerable wheels. In particular, the rear axle assembly could be designed analogously to the front axle assembly.

A platform according to the invention could also have more than two axle assemblies, for example two rear axle assemblies in addition to a front axle assembly.

Such a platform can also be referred to as a skateboard platform.

The rear axle assembly 3 is formed with a rigid axle 4 in the embodiment. This is suspended from a base unit 6 of the rear axle assembly 3 by means of leaf spring assemblies 5 . The inherently rigid base unit 6 is fastened to the chassis 1 by means of a screw connection.

The wheels 7 rotatably mounted by the rigid axle 4 can be driven individually or together by at least one electric motor, for example by means of wheel hub motors. An additional mechanical braking device for each wheel, as is known, can be provided. However, an embodiment without an additional mechanical braking device, which brakes the rotation of the respective wheel about its wheel axis, is also conceivable and possible. In this case, braking forces that brake the rotation of the respective wheel about its wheel axle could only be exerted by at least one drive motor for the wheels 7 .

A drive for the wheels of the rear axle assembly could also be omitted.

In the exemplary embodiment, the front axle assembly 2 has an inherently rigid base unit 10 which carries the wheel suspension. The base unit 10 is used to connect to the chassis 1. The front axle assembly 2 is preferably connected to the chassis 1 by a screw connection.

The right and left wheels 11 of the front axle assembly 2 are rotatably mounted on a respective wheel carrier 12 about a respective wheel axle 13 . The wheels 11 are steerable. To this end, the right and left wheel carriers 13 are pivotably mounted about pivot axes 14 .

The wheels 11 of the front axle assembly 2 are individually driven about the respective wheel axle 13 by a respective electric motor 15 . In the exemplary embodiment shown, the electric motors are designed in the form of wheel hub motors. It would also be conceivable and possible for electric motors attached to the base unit 10 to be present, which are connected to the respective wheel 11 via a respective drive shaft.

In the exemplary embodiment, there is also a mechanical braking device for each wheel 11 . In this context, a brake disc 16 and a brake caliper 17 are shown in FIG.

It would also be conceivable and possible to have a design without a mechanical braking device which brakes the rotation of the respective wheel about its wheel axle. In this case, braking forces that brake the rotation of the respective wheel about its wheel axle could only be exerted by the electric motors 15 .

In the exemplary embodiment, the wheels 11 of the front axle assembly 2 are suspended on the base unit 10 and thus on the chassis 1 via a trailing arm wheel suspension. There is a trailing arm 20 for both the right wheel and the left wheel 11 , which is connected to the base unit 10 so that it can pivot about a respective transverse axis 21 . The transverse axes 21 are perpendicular to the longitudinal direction of the platform and are preferably horizontal.

The longitudinal direction of the platform is parallel to the direction of straight travel.

The wheel carriers 12 are mounted on the respective trailing arm 20 such that they can pivot about a respective pivot axis 14 in order to enable the respective wheel 11 to be steered.

The pivoting of the trailing arms 20 about the transverse axes 21 are spring-loaded. For this purpose, there is a torsion bar spring 22 for the respective trailing arm 20 . Each torsion bar spring 22 extends coaxially to the respective transverse axis 21. So that the torsion bar springs 22 can be as long as possible, i.e. can have a length greater than half the track width, the transverse axes 21 for the right and left trailing arm 20 are offset from one another, related in the exemplary embodiment to the longitudinal direction of the platform, i.e. one of the two transverse axes 21 is further forward and the other of the two transverse axes 21 further back. The offset of the transverse axes 21 could also take place in height instead or in addition.

In the exemplary embodiment, the trailing arms 20 on the right and left sides are of different lengths corresponding to the offset of the transverse axes 21, so that the wheel axles 13 of the right and left wheels 11 coincide. The wheel axles 13 of the right and left wheels 11 could also be offset from one another in relation to the longitudinal direction of the platform.

In a region spaced apart from the connection to the respective trailing arm 21, the respective torsion bar spring 22 is non-rotatably connected to the base unit 10 (and via the base unit 10 to the chassis 1). A holding part 23 is used for this purpose, which is in a non-rotatable connection with the respective torsion bar spring 22 . In order to enable the spring force to be adjusted, a respective holding part 23 is connected to the respective torsion bar spring 22 so that it can be displaced in relation to the transverse direction parallel to the transverse axes 21 and is mounted on the base unit 10 so that it can be displaced in the transverse direction. A respective holding part 23 can thus also be displaced in the transverse direction with respect to the chassis 1 . To postpone the respective

Gen holding part 23 in the transverse direction is preferably in each case an electrically operated control part 24 (ie an actuator) available. The suspension can thus be adjusted by means of an electrical control device (not shown in the figures), even when the vehicle is in operation.

The non-rotatable connection of the respective holding part 23 with the respective torsion bar spring 22 takes place via a respective connecting piece 25. Its rotational position relative to the holding part 23 can be adjusted and fixed, whereby a pretension of the respective torsion bar spring 22 can be adjusted.

The pivoting of the respective trailing arm 20 is damped by a respective damper 26 . In the exemplary embodiment, rotary dampers are provided as dampers 26, via which the longitudinal links 20 are mounted on a downwardly projecting leg 10a of the base unit 10 such that they can pivot about the lower transverse axes 21. The connections between the dampers 26 and the trailing arms 20 on the one hand and the legs 10a on the other hand can be made by screw connections (not shown in the figures).

The wheel carriers 12 of the right and left wheel 11, which can be pivoted about the pivot axes 14 for steering the wheels 11, are connected to one another, as a result of which the pivoting of the right and left wheel carriers 12 about the respective pivot axis 14 is coupled. A respective rod part 28, 29 is articulated (= articulated) on the respective wheel carrier 12. In the exemplary embodiment, the articulated connections are designed as ball joints. The right and left rod members 28, 29 are connected to each other by a connecting unit 30 interposed therebetween. The right rod part 28 is articulated at a right connection point 30a of the connection unit 30 on the connection unit 30, in the exemplary embodiment via a ball joint, the left rod part 29 is articulated at a left connection point 30b of the connection unit 30 on the connection unit 30, in the exemplary embodiment via a ball joint.

The articulated connections between the rod parts 28, 29 and the wheel carriers 12 and/or between the rod parts 28, 29 and the connecting unit 30 could also take place in other ways, for example via cardan joints.

The rod parts 28, 29 are formed in one piece in the embodiment. A multi-part design, for example in the form of two parts connected to one another in an articulated manner, is conceivable and possible.

The rod parts 28, 29 and the connecting unit 30 arranged in between and connecting the rod parts 28, 29 thus form a type of articulated connecting rod which connects the wheel carriers 12 of the right and left wheels 11 to one another and mechanically couples them.

The steering of the wheels 11, ie the setting of the angular position of the wheels 11 about the pivot axes 14, takes place, as already mentioned, only by means of drive and/or braking forces. There is therefore no steering mechanism by which the rotation of a steering wheel is mechanically transmitted to the angular position of the wheels. There are also no additional steering actuators which are not used to drive the wheels about the wheel axles 13 but only to actively adjust the angular position of the wheels about the pivot axles 14 .

A steering of the wheels only by means of driving and braking forces is already known in principle and does not have to be explained in detail in this document. An electrical control device used for this purpose is not shown, and this is generally not part of the platform either.

At a specific steering angle of the wheels, a curve with a specific radius is traversed. Depending on the curve radius, the inner wheel must be pivoted more than the outer wheel. Such a different pivoting of the wheels is advantageously already due to the geometry of the mechanical coupling of the wheels, i.e. the wheels have the geometry of their mechanical coupling depending on the

Steering angle on a different toe difference angle, as is known.

The toe difference angle denotes the difference between the angular position of the right and the left wheel of one of the axle assemblies, here the front axle assembly.

However, the optimal setting of the toe difference angle for a specific steering angle can only be approximated by the geometry of the mechanical coupling. The optimal value for the toe difference angle also depends on the speed for a specific curve radius due to dynamic effects, such as those that occur in particular on the tires.

To adjust the toe difference angle between the right and left wheel 11 at a specific steering angle, the connection unit 30 is adjustable, as explained below.

9 in an exploded view and FIG. 10 in a longitudinal section in simplified form, the connection unit 30 has, in the exemplary embodiment shown, an actuator 31 in the form of an electric motor with a stator 31a and a rotor 31b. The rotor 31b forms a gear nut with an internal thread 32. This is in engagement with an external thread 33 of a gear rod 34. Thus, a helical gear is formed, which is preferably self-locking. The stator 31a is rigidly connected to a gear rod 35, for example by means of a screw connection. The gear rod 35 is hollow in the end section, so that the gear rod 34 can move into this end section.

The gear rods 34, 35 lie on a common straight line parallel to the transverse direction and protrude from a housing 36 of the connecting unit 30 on both sides. The stator 31a is secured against rotation in the housing 36 but is mounted so that it can be displaced in the transverse direction. For this purpose, the stator 31a in the exemplary embodiment has a groove 37 into which a projection of the housing (not visible in the figures) engages.

The housing 36 is attached to the supporting legs 10b of the base unit 10 by means of fastening parts 38, the transmission rods 34, 35 also being mounted displaceably in the transverse direction by these supporting legs 10b.

Modified constructions, in which a housing of the connection unit itself is slidable in the transverse direction with respect to the chassis, the housing could be formed directly by the stator, are conceivable and possible.

The transmission rods 34, 35 can thus be adjusted axially by the actuator 31, with the distance between the connection points 30a, 30b being adjusted.

If the actuator 31 is not operated, the distance between the connection points 30a, 30b is fixed and the movement of the two rod parts 28, 29 is synchronously coupled via the connection unit 30 (= they move simultaneously in the same direction and with the same speed).

The force to adjust the toe difference angle does not have to be applied by the actuator 31 of the connection unit 30 alone. Advantageously, such steering forces can be exerted on the wheels 11 by the drive and/or braking forces exerted on the wheels 11 about the respective wheel axle 13 with respect to the pivot axes 14 that they support the adjustment of the connecting unit 30 . As a result, the actuator 31 of the connection unit only requires a small amount of force to adjust the toe difference angle. However, a correspondingly high holding force can be exerted by the connection unit 30 in order to hold the set toe difference angle in all driving situations.

According to the design of the connection unit 30 of this exemplary embodiment, the distance between the connection points 30a, 30b can be actively adjusted by means of the actuator 31, via which the connection unit 30 is connected to the rod parts 28, 29 connected to the wheel carriers 12. The effective length of the connection unit is thus adjusted by means of the actuator 31 . Other configurations of the connecting unit 30 according to this first basic mode of operation are conceivable and possible, as explained further below.

playfully explained.

According to a second principle of operation of the connection unit, the distance between the connection points is not adjusted by the at least one actuator, but rather the adjustability of the distance between the connection points is released and blocked by the at least one actuator, as also explained further below.

If, in the course of adjusting the toe difference angle, driving and/or braking forces are exerted on at least one wheel of an axle assembly in order to steer it, driving and/or braking forces can be exerted on at least one wheel of another axle assembly in order to to counteract forces exerted for the adjustment of the toe difference angle, so that the overall condition of the motor vehicle, for example the speed, remains as unaffected as possible.

11 and 12 show schematic representations of the platform when cornering with different radii. By adjusting the toe difference angle 39 of the front wheels 11 by adjusting the connection unit 30, the toe difference angle 39 can be adapted to the respective curve radius. This is illustrated in FIGS. 11 and 12 in that the drawn-in auxiliary lines, which extend the wheel axis of the respective front and rear wheel 11, 7, intersect at a common point for different steering angles of the front wheels. Dynamic effects are not taken into account in these representations. As already mentioned, the optimal value for the toe difference angle at a specific radius also depends on the speed due to such dynamic effects as occur in particular on the tires. In this case, the toe difference angle can also be set optimally as a function of the speed.

If the rear wheels can also be steered, they can also be steered when cornering. The rear axle assembly can be designed in a similar way to the front axle assembly and the toe difference angle of the rear wheels can be adjusted to the respective curve radius by adjusting the connection unit associated with these wheels.

13 and 14 show the possibility of braking a motor vehicle by putting the steerable front wheels 11 in the position of a very strong toe-in or toe-out.

If the rear wheels are also designed to be steerable, the rear wheels can be brought into a strong toe-in or toe-out in addition to or instead of the front wheels in order to brake the vehicle.

The toe difference angle between the right and left wheels is preferably more than 10°, particularly preferably more than 30°, for braking the motor vehicle. The motor vehicle can be braked in this way while driving, or a parking brake can be implemented in this way.

When braking while driving in this manner, the front and/or rear wheels can be steered appropriately by means of driving and/or braking forces to keep the motor vehicle stable.

In one embodiment, in which both the toe difference angle between the front wheels and between the rear wheels is adjustable, it is possible to turn the vehicle at a standstill. This is shown schematically in FIG. The angular positions of the front wheels 11 and rear wheels 7 about their respective pivot axes are set in such a way that all wheels 11, 7 are tangential to a common circular line 27, see FIG.

A second embodiment of the invention is shown in FIGS. 16 to 18. FIG. Apart from the differences described below, the design can correspond to the first exemplary embodiment and its description with the possible modifications described can be used analogously.

The connecting unit 30 has two arms 40 and 41 at an angle to one another. The arms 40, 41 can be pivoted relative to one another about a common, preferably vertical, axis 42, so that the angle 43 between the arms 40 and 41 can be changed. The axis 42 is in the area of one end of the arms 40, 41. In the area of the other ends of the arms 40, 41 spaced apart from the axis 42 there are connection points 30a, 30b, at which the arms 40, 41 with the right and left Rod part 28, 29 are articulated. By pivoting the arms 40, 41, the distance between the connection points 30a, 30b and thus the effective length of the connection unit 30 can be changed, as a result of which the toe difference angle between the wheels 11 can be changed.

An actuator 44 is provided in the form of an electric motor, of which the angle 43 between the arms 40, 41 can be actively adjusted. A gear, which is not specifically shown here, is integrated into the actuator. The output shaft of this gear works together with a synchronization gear 45 acting between the first and the second arm 41, 42, which causes a synchronous (= simultaneous and running at the same speed) oppositely directed pivoting of the arms 40, 41 about the axis 42. The gearing of the actuator can be self-locking to block the pivoting of the arms 40, 41 about the axis when the actuator is not activated. Instead of a self-locking design of the gear (or also in addition thereto), an electrically controllable blocking element 46 can be present, which can block the pivoting of the arms 40, 41.

The axle 42 can be rigidly connected to the chassis 1, preferably via the base unit 10 to which it is attached (not shown in the figures). A cantilever arrangement of the axis 42 is also conceivable and possible.

A third embodiment of the invention is shown in FIGS. 19 to 21. FIG. Apart from the differences described below, the design corresponds to that of the second exemplary embodiment.

In this exemplary embodiment, the actuator 47 is designed as an electrically controllable blocking element, with which the pivotability of the arm 40 relative to the arm 41 can be released and blocked.

The actuator 47 can, for example, have an electromagnet which acts on a magnetorheological fluid which, when activated, blocks the relative rotation between two parts.

In the locked state of the connection unit 30, the distance between the connection points 30a, 30b is fixed. The toe difference angle between the right and the left wheel 11 is thus fixed for a respective steering angle. In the release state of the linkage unit 30, the angle 43 between the arms 40, 41 can be adjusted and adjusted to a desired value by steering the wheels 11 individually. This individual steering of the wheels 11 in turn takes place only by means of driving and braking forces which act on the respective wheel about its wheel axis.

For example, on a platform in which only the front wheels can be steered, the parking brake can be activated in the following manner when the vehicle is stationary: To bring the front wheels 11 into a swivel position in which they have a sufficiently strong toe-in , in the release state of the connecting unit 30, a torque is exerted in the forward movement direction by the electric motors driving the front wheels about the wheel axles. The electric motors, which drive the rear wheels, exert a correspondingly strong torque in the opposite direction (i.e. in the direction of movement to the rear). Overall, the vehicle stops. However, due to the torque exerted on the front wheels, they pivot about the pivot axes 14. The exertion of the torque is terminated when the desired pivot positions of the front wheels 11 have been reached. The connection unit 30 is brought into the blocking state by the actuator 47 .

When driving, in the release state of the connection unit 30, the pivot position

of a wheel 11 can be changed independently of the other wheel 11 by accelerating or braking this wheel individually. When the desired pivoting position is reached, the connecting unit 30 is again brought into the blocking state by the actuator 47, whereupon the wheels 11 can be steered together. As a result, the toe difference angle was adjusted in the desired manner.

In an analogous manner, the toe difference angle of these wheels can be adjusted with steerable rear wheels.

A fourth embodiment of the invention is shown in FIGS. 22 to 24. Apart from the differences described below, the design can correspond to the first exemplary embodiment and its description with the possible modifications described can be used analogously.

The connection unit 30 here has two piston-cylinder units. In the cylinder 50 of the respective piston-cylinder unit, a piston 51 is arranged, which is connected via a respective piston rod 53 to the respective rod part 28, 29 in an articulated manner. The pistons 51 and the parts of the piston rods 53 located in the respective cylinder 50 are indicated in FIG. 24 with dashed lines. The connection points 30a, 30b are therefore located at the end of the respective piston rod 53 remote from the respective piston 51.

A respective piston 51 delimits a first and a second cylinder chamber 54, 55 in the respective cylinder from one another. The respective first cylinder chamber 54 is located on the side facing the respective connection point 30a, 30b, the respective second cylinder chamber 55 is located on the side of the respective piston 51 facing away from the respective connection point 30a, 30b.

The cylinder chambers 54, 55 are connected to a valve 56 via hydraulic lines (shown only in FIG. 24). There is hydraulic fluid in the cylinder chambers and in the hydraulic lines. The valve 56 can be adjusted between different valve positions by an electrically actuable actuator 57 .

In a first valve position, the first cylinder chambers 54 of the two piston-cylinder units are connected to one another via the hydraulic lines and the valve 56, and the second cylinder chambers 55 of the two piston-cylinder units are connected to one another. The pistons 51 of the two piston-cylinder units can thus only move synchronously (= simultaneously in the same direction and at the same speed) and the movement of the two rod parts 28 , 29 is thus synchronously coupled via the connecting unit 30 . In this valve position (in which the valve is in the position shown in FIG. 24), the adjustment of the toe difference angle is blocked at a specific steering angle.

In a second valve position (the middle of the valve positions shown in Fig. 24) is via the hydraulic lines and the valve 56, the first cylinder chamber 54 of the right piston-cylinder unit with the second cylinder chamber 55 of the right piston-cylinder unit and the first Cylinder chamber 54 of the left piston-cylinder unit connected to the second cylinder chamber 55 of the left piston-cylinder unit. The pistons of the piston-cylinder units can thus move independently of one another. In this valve position, the adjustment of the toe difference angle in FIG. 24 is released.

As can be seen from FIG. 24, the valve can have a third valve position. In this third valve position, the hydraulic lines leading to the first cylinder space 54 and the hydraulic lines leading to the second cylinder space 55 of the respective piston-cylinder unit are blocked by the valve. The pistons of the piston-cylinder units are thus fixed. In this valve position, the pivoting of the wheel carriers about the pivot axes are blocked. This can be advantageous if one of the electric motors 15 fails.

In a further modified embodiment, the connecting unit could be formed by a piston-cylinder unit, of which the piston is connected to one of the two rod parts 28, 29 and the cylinder to the other of the two rod parts 28, 29.

wherein the cylinder is displaceable in the transverse direction and the piston is actively displaceable relative to the cylinder by an actuator.

Apart from the electric motors described for the individual wheel drives and the actuators described, the simplified figures do not show other parts of the electrical equipment, such as electrical lines and sensors, for example sensors for detecting the angular position of the wheel carrier 12 about the pivot axis.

LEGEND TO THE NOTES:

1 chassis 30b junction 2 front axle assembly 31 actuator

3 Rear Axle Assembly 31a Stator

4 rigid axle 31b rotor

5 leaf spring package 32 internal thread

6 base unit 33 external threads

7 wheel 34 gear rod

10 base unit 35 gear rod 10a leg 36 housing

10b supporting leg 37 groove

11 wheel 38 fastener

12 wheel carrier 39 toe difference angle 13 wheel axle 40 arm

14 pivot axis 41 arm

15 electric motor 42 axis

16 brake disc 43 angle

17 caliper 44 actuator

20 trailing arm 45 synchronization 21 transverse axle gear

22 torsion bar spring 46 blocking element

23 holding part 47 actuator

24 actuator 50 cylinder

25 - connector 51 piston

26 damper 53 piston rod

27 circular line 54 first cylinder space 28 rod part 55 second cylinder space 29 rod part 56 valve

30 connection unit 57 actuator

30a junction

Claims (15)

patent claims 1. Platform for at least four-wheel motor vehicles with electric drive, having at least one front axle assembly (2) forming a front axle and at least one rear axle assembly (3) forming a rear axle, which are spaced apart from one another in a longitudinal direction of a supporting chassis (1) of the platform and of which at least one of the axle assemblies (2) has wheels (11) which can be steered about respective pivot axes (14) and which are mounted on wheel carriers (12) which can pivot about the pivot axes (14) so as to be rotatable about wheel axles (13), the right and left wheel (11) of this axle assembly (2) are each driven individually by a respective electric motor (15) with respect to rotation about the respective wheel axle (13) and for coupling the wheel carrier (12) of the right and left wheel (11) with respect to the pivot positions of these wheel carriers (12) about the pivot axes (14) on the right wheel carrier (12) a right rod part (28) is articulated and on the left wheel carrier (12) a left one s rod part (29), which is connected to the right rod part (28), the steering of the wheels (11) only by means of drive and/or braking forces, characterized in that the rod parts (28, 29) are connected to one another via an adjustable connection unit (30) for adjustability of the toe difference angle (39) between the right and left wheel (11), which is connected at a right connection point (30a ) is connected to the right rod part (28) and at a left connection point (30b) to the left rod part (29) and has at least one actuator (31, 44, 47, 57) from which the distance between the right and left connection point (30a, 30b) is actively adjustable or by which a change in the distance between the right and left connection points (30a, 30b) can be released and blocked. 2. Platform according to claim 1, characterized in that the toe difference angle (39) between the right and left wheel (11) can be adjusted by more than 5°, preferably more than 10°, by means of the adjustable connection unit (30). 3. Platform according to claim 1 or 2, characterized in that the right rod part (28) is articulated to the right connection point (30a) of the connection unit (30) and the left rod part (28) is articulated to the left connection point (30b) of the connection unit ( 30) is connected. 4. Platform according to one of Claims 1 to 3, characterized in that the connection unit (30) has a self-locking helical gear (32, 33) which can be driven by the actuator (31) and by means of which the distance between the right and left connection points (30a, 30b ) is adjustable. 5. Platform according to claim 4, characterized in that the right-hand connection point (30a) from the end of a right-hand gear rod (34) protruding from a housing (36) of the connection unit (30) and the left-hand connection point (30b) from the end of a (36) of the connecting unit (30) protruding left gear rod (35), the gear rods (34, 35) being axial from the actuator (31). 6. Platform according to one of Claims 1 to 3, characterized in that the connecting unit (30) has two arms (40, 41) which are at an angle to one another and can be pivoted relative to one another about an axis (42) and which are spaced apart from the axis (42) each have one of the connection points (30a, 30b), the angle (43) between the arms (40, 41) being adjustable by at least one actuator (44) or the mutual pivoting of the arms (40, 41) about the axis (42 ) can be released and blocked by at least one actuator (47). 7. Platform according to claim 6, characterized in that between the first and second arm (40, 41) a synchronizing gear (45) acts, which causes a synchronous opposite pivoting of the arms (40, 41) about the axis (42). 8. Platform according to one of claims 1 to 3, characterized in that the connecting unit (30) has at least one hydraulic piston-cylinder unit with a cylinder (50) arranged in a piston (51) which is adjustable by at least one actuator or whose position in the cylinder can be released and blocked by at least one actuator (57). 9. Platform according to one of Claims 1 to 8, characterized in that both the front axle assembly (2) and the rear axle assembly (3) have steerable wheels (11, 7) whose wheel carriers are attached to the wheel carriers ( 12) articulated rod parts (28, 29) and an adjustable connection unit (30) connecting the rod parts. 10. Platform according to claim 9, characterized in that the wheels (11, 7) of the front and rear axle assembly (2, 3) can be brought into a position in which they are tangential to a common circular line (27). 11. Motor vehicle having a platform according to any one of claims 1 to 10. 12. Method for setting the toe difference angle of the steerable wheels (11) of an axle assembly (3) of a motor vehicle according to claim 11, characterized in that the toe difference angle between the wheels (11) is adjusted by means of the actuator (31, 44) of the connection unit (30). or that the ability to change the toe difference angle is enabled by the actuator (47, 57) of the connection unit (30) and the toe difference angle is changed by different steering of the right and left wheel (11) by means of drive and/or braking forces acting around the wheel axles (13). and as a result the variability of the toe difference angle is again blocked by the actuator (47, 57). 13. The method according to claim 12, characterized in that for driving the motor vehicle through curves with different radii, the toe difference angle between the right and left wheel (11) of the at least one axle assembly (2) having steerable wheels is adapted to the respective curve radius becomes. 14. The method according to claim 12 or 13, characterized in that for braking the motor vehicle the toe difference angle of the steerable wheels (11) of at least one axle assembly (2, 3) to a size of more than 5 °, preferably more than 10 ° is set. 15. The method according to any one of claims 12 to 14, characterized in that for turning the motor vehicle the toe difference angles between the wheels (11, 7) of all axle assemblies (2, 3) are adjustable and the angular positions of the wheels (11, 7) are adjusted be that the wheels (11, 7) are tangential to a common circular line (27). 9 sheets of drawings