Motor vehicle with lifting bridge and method of operating the same

Abstract

A motor vehicle (50) having at least one steering axle (64), at least one drive axle (74, 76) and at least one lifting axle (78), the lifting axle having at least one actuator (104, 106) for raising and lowering the same, wherein the wheels (82, 84) of at least one drive axle can be driven electrically at least in a supporting manner by means of at least one electric machine which can be operated as an electric motor and as a generator and can be driven as a generator in regenerative operation, and wherein the electric machine is connected to a battery (92) and to a control and / or regulating device (94), the control and / or regulating device being designed to control and / or regulate the operation of the electric machine and to control and / or regulate the operation of the lifting axle. The invention provides that a control and / or regulating device (94) is connected to a sensor (120) for detecting wheel slip of wheels (82, 84) of at least one drive axle (74, 76), and that the control and / or regulating device (94) is designed such that, if wheel slip occurs on at least one wheel of at least one drive axle, the control and / or regulating device can send a control command to at least one actuator (104, 106) of a lifting axle (78) during an activated regeneration operation in order to raise the lifting axle and thereby relieve the wheels (86) thereof. The invention also relates to a method for operating such a motor vehicle.

Description

Technical Field

[0001] The invention relates to a motor vehicle for transporting goods and / or people on a roadway, comprising at least one steering axle, at least one drive axle and at least one lifting axle, the lifting axle having at least one actuator for raising and lowering the lifting axle, wherein the wheels of the at least one drive axle can be driven electrically at least in a supporting manner by means of at least one electric machine that can be operated as an electric motor and as a generator and can be driven as a generator in a regenerative operation of the motor vehicle, and wherein the at least one electric machine is connected to a battery and to a control and / or regulating device that is designed to control and / or regulate the electric motor and generator operation of the at least one electric machine and for controlling and / or regulating the operation of the at least one lifting axle. The invention also relates to a method for operating such a motor vehicle and a control and / or regulating device for carrying out the method. Background Art

[0002] Motor vehicles are known from the prior art which can be driven at least partially with the aid of an electric motor fed by a battery. During regenerative operation (in which the motor vehicle rolls without drive and the electric motor is operated as a generator via the wheels), the vehicle is decelerated and the generated electrical energy is fed to the battery for extending the range of the motor vehicle. As a result, the use of purely mechanical, friction-based brake systems is often not necessary during normal operation of the motor vehicle.

[0003] According to DE 10 2017 213 199 A1, an adjustment device for an electrically operated commercial vehicle and an operating method thereof are known. The motor vehicle has a front axle and at least two rear axles and a pneumatic level adjustment device for at least one of the two rear axles. In addition, the motor vehicle also has at least one motor-driven rear axle wheel and a battery, which supplies power to the motor during the motor operation. In regenerative operation (wherein the motor works as a generator and is driven by the rear axle wheels), in order to charge the battery, the level adjustment device adjusts the vehicle relative to the level of the lane and the adjustable rear axle as follows, that is, substantially equal loads act on the two rear axles. Regenerative operation should be improved thereby. This optimization of regenerative operation is only provided in the case of motor vehicle ramp driving. For this reason, an air spring system is required on the vehicle to distribute the load on the rear axle. Summary of the invention

[0004] Based on this background, the object of the present invention is to propose a motor vehicle with which a further improved regenerative operation can be achieved. In addition, a method for operating such a motor vehicle is to be specified.

[0005] This object is achieved by the motor vehicle according to the invention and by the method according to the invention.

[0006] The invention therefore relates firstly to a motor vehicle for transporting goods and / or people on a roadway, comprising at least one steering axle, at least one drive axle and at least one lifting axle, the lifting axle having at least one actuator for raising and lowering the lifting axle, wherein the wheels of the at least one drive axle can be driven electrically at least in a supporting manner by means of at least one electric machine which can be operated as an electric motor and as a generator and can be driven as a generator in a regenerative operation of the motor vehicle, and wherein the at least one electric machine is connected to a battery and to a control and / or regulating device which is designed to control and / or regulate the electric motor and generator operation of the at least one electric machine and to control and / or regulate the operation of the at least one lifting axle.

[0007] In order to achieve the product-related task, it is provided in the motor vehicle that a control and / or regulating device is connected to a sensor for detecting wheel slip on the wheels of at least one drive axle, and the control and / or regulating device is designed as follows: when wheel slip occurs on at least one wheel of at least one drive axle, the control and / or regulating device can send a control command to at least one actuator of the lifting axle to raise the lifting axle and thereby relieve the load on its wheels during an activated regeneration operation.

[0008] It is known that when the motor vehicle is traveling forward without drive, the wheels of at least one drive axle are not actively driven by at least one electric machine or internal combustion engine. By actuating the brake pedal on the driver's side or activating an automatic braking system (e.g., distance assistance, emergency brake assistance, speed assistance), a regenerative mode is initiated and, if necessary, a purely mechanical, friction-based braking mode is supplemented therewith until a predetermined speed is reached or until the motor vehicle comes to a complete standstill. In the regenerative mode, the electric machine is operated in generator mode. The electrical energy generated in this way is fed into the battery of the motor vehicle, while in the purely mechanical braking mode, the kinetic energy dissipated by the motor vehicle is converted into heat energy that cannot be used again from a technical point of view.

[0009] By means of the embodiment of the motor vehicle according to the invention, good traction can be ensured for the wheels of the at least one driven axle in the regenerative mode even in the event of wheel slip, since the wheels of the at least one driven axle which are not lifted are subjected to greater load forces. In addition, the regenerative mode is further optimized with respect to the electrical energy that can be generated, since the mechanical loads generated by the electric machine in the generator mode can be well supported by the vehicle wheels on the roadway.

[0010] A motor vehicle constructed in this way can be operated fully electrically or by means of a combination of at least one similar electric machine and an internal combustion engine, that is, by means of a hybrid drive. In addition, such a motor vehicle can optionally be equipped with an air spring system for level adjustment and load-dependent spring adaptation. In this case, each air spring can be equipped with a pressure sensor. By evaluating the pressure measurement values ​​by means of the control and / or regulating device, the vertical load acting on the wheels of the axle can be determined.

[0011] In the motor vehicle proposed here, it is preferably provided that the control and / or regulating device is designed in such a way that it can at least partially lift the non-driven lifting axle and thereby at least partially relieve it by sending control commands to at least one associated actuator, so that the additional load force acting on the at least one driven axle can be variably adjusted. Thus, by at least partially lifting the lifting axle, the load force acting on the at least one driven axle can be continuously varied, wherein the wheels of the lifting axle can still be in full but relieved contact with the roadway.

[0012] The at least one actuator mentioned on the lifting axle is preferably pneumatically actuable in commercial vehicles, because such motor vehicles usually have a compressed air generator for their mechanical brake systems. Alternatively, an electric motor or hydraulically operated actuator can also be used to raise and lower the lifting axle.

[0013] In a commercial vehicle designed as a tractor, with a tractor and a three-axle tractor trailer, it can be provided, for example, that by completely lifting the lift axle or its wheels from the roadway, the load forces acting on the two drive axles are each increased by 50%. As a result, wheel slip and the resulting loss of wheel traction are avoided on the two drive axles that can be driven by electric motors, and the regenerative operation is also improved. If the described partial or complete lifting of the lift axle is not possible in the event of wheel slip, the braking effect of the electric motor operating in generator mode cannot be supported on the roadway due to the wheel slip. In addition, a well-defined driving behavior of the motor vehicle is no longer ensured due to the wheel slip.

[0014] Furthermore, preferably, provision is made for at least each wheel of at least one drive axle to be assigned a rotational speed sensor for detecting slip by means of the control and / or regulating device, by means of which the control and / or regulating device is connected in signal or data technology. By evaluating the wheel rotational speed of at least one drive axle determined by the rotational speed sensor by means of the control and / or regulating device, slip can be reliably detected during regeneration operation or a possible loss of traction of the drive axle can be detected.

[0015] Furthermore, at least one sensor designed as a rotational speed sensor can be arranged on the wheels of the lift axle and / or on the wheels of the steered axle of the tractor, on the wheels of the drive axle, in order to further improve the detection of wheel slip by means of the control and / or regulating device.

[0016] Furthermore, it can be provided that at least one inclination sensor is associated with the control and / or regulating device, by means of which the inclination of the roadway on which the motor vehicle is traveling can be determined, and the control and / or regulating device is connected to the at least one inclination sensor by means of signal or data technology. By means of the inclination sensor it can be detected whether the motor vehicle is moving on a substantially horizontal roadway. In this case, when a possible slip occurs on at least one drive axle, it is preferentially provided that the lifting axle is raised in the regeneration mode.

[0017] The motor vehicle is configured, for example, as a single-section truck or as a tractor with a tractor and a tractor trailer, wherein the single-section truck or the tractor trailer can be driven at least in a supporting manner by means of at least one electric motor. This results in a particularly flexible use of the motor vehicle.

[0018] Furthermore, it is preferably provided that the control and / or regulating device is designed as a compact controller having at least one digital computing unit. As a result, wheel slip detection can be realized in real time by means of rotation speed sensors of the wheels respectively assigned to the axles. Furthermore, inclination detection can be realized by means of at least one inclination sensor and the control and / or regulation of at least two actuators for raising the lifting axle and lowering the lifting axle in regeneration mode. In the case of two-section motor vehicles (e.g. a tractor with a tractor and a trailer or a truck with a trailer), preferably both the tractor and the trailer are also equipped with inclination sensors.

[0019] The invention also relates to a method for operating a motor vehicle for transporting goods and / or people on a roadway, the motor vehicle having at least one steering axle, at least one drive axle and at least one lifting axle, the lifting axle having at least one actuator for raising and lowering the lifting axle, wherein the wheels of the at least one drive axle can be driven electrically at least in a supporting manner by means of at least one electric machine that can be operated as an electric motor and as a generator and can be driven as a generator in the regenerative operation of the motor vehicle, and wherein the at least one electric machine is connected to a battery and to a control and / or regulating device for controlling and / or regulating the electric motor and generator operation of the at least one electric machine and for controlling and / or regulating the operation of the at least one lifting axle. The method comprises the following method steps:

[0020] a) checking whether the motor vehicle is in regenerative operation by means of the generator operation of the electric machine, generating and transferring electrical energy to the battery,

[0021] b) wheel slip is detected on at least one driven axle, and

[0022] c) Raising the driveless lifting bridge when the conditions specified in method steps a) and b) in each case are met.

[0023] Thus, in the regenerative mode, at least one drive axle and thus its wheels are subjected to significantly increased vertical load forces. As a result, more electrical energy is generated and fed to the battery due to the improvement in the traction of the wheels driven by the electric machine.

[0024] According to the method, it can also be provided that the load force acting on the at least one drive axle is variably adjusted within a limit range by at least partially raising or lowering the at least one lifting axle. It can be useful here for the at least one lifting axle to be raised only to such an extent that its wheels are relieved of load to the greatest extent possible, but still in contact with the roadway. In this way, on the one hand, the desired load increase is produced at the wheels of the two driven drive axles, and on the other hand, a return of the lifting axle to its completely lowered operating position can be achieved very quickly.

[0025] Preferably, provision is made for the wheel slip to be measured by means of a rotational speed sensor assigned to the control and / or regulating device, which is assigned to each wheel of the at least one drive axle, thereby enabling reliable detection of wheel slip at the wheels of the at least one drive axle.

[0026] Furthermore, rotational speed sensors can be arranged on the wheels of the lifting axle and / or the wheels of the steering axle and the driving axle of the tractor in order to further improve the detection of wheel slip by means of the control and / or regulating device. The rotational speed measured values ​​thereof are used according to the method. It is particularly advantageous that data of an ABS braking system already present on the motor vehicle can be used by the control and / or regulating device to achieve the described purpose.

[0027] Finally, it can be provided that at least one inclination sensor assigned to the control and / or regulating device is used to detect whether the roadway inclination of the raised lift bridge can be used for the regeneration operation. The invention provides that the lift bridge is only raised if the roadway inclination does not exceed a predetermined value. The roadway inclination that should not be exceeded can be, for example, an 8% roadway inclination. In particular, when driving on steep slopes, it is ensured that the motor vehicle can be braked as reliably as possible using the small traction forces available on the possibly slipping wheels of the lift bridge.

[0028] The invention further relates to a control and / or regulating device which is situated in a motor vehicle and which is designed in such a way that a method according to at least one method claim can be carried out by means of it. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to better understand the present invention, the specification is accompanied by drawings. Among them:

[0030] Figure 1 The schematic diagram shows that when using 1.0m / s 2 The force acting on a known motor vehicle during a one-time deceleration from 85 km / h to 70 km / h with a constant negative acceleration, and

[0031] Figure 2 The forces acting on the motor vehicle according to the invention during the same deceleration process in recuperation mode when the lifting axle is raised are shown in a schematic diagram. Specific implementation plan

[0032] therefore, Figure 1 The schematic diagram shows that when using 1.0m / s 2 The force acting on a known motor vehicle during a one-time deceleration process in which the speed is adjusted from 85 km / h to 70 km / h by a constant negative acceleration.

[0033] The motor vehicle 10 is shown here merely by way of example as a tractor 12 with a tractor 14 having a coupling point 16, to which a trailer 18 is articulated. The tractor 14 has a steering axle 20 and a drive axle 22 arranged behind the steering axle in relation to the forward travel direction of the trailer 18, which drive axle can be driven, for example, by an internal combustion engine of the tractor 14. Here, the trailer 18 has merely by way of example three rear axles 24, 26, 28, which are combined into a rear axle group 32 in a rear end region 30 of the trailer 18 pointing away from the tractor 14. At least one of the three rear axles 24, 26, 28 can be driven at least partially with the aid of an electric motor.

[0034] The motor vehicle 10 or the two-section tractor 12 moves on a substantially horizontal track 34 at an initial speed v1, as indicated by a direction arrow 36. At least one of the three rear axles 24, 26, 28 of the tractor trailer 18 can be designed as a lifting axle or lifting axle for temporarily and at least partially lifting off the track 34 to reduce the rolling resistance and tire wear of the tractor trailer 18.

[0035] The trailer 18 is loaded with a load 38 having a weight m1, which is only shown symbolically in the figure. The trailer 18 also has a deadweight m2, while the tractor 14 has a deadweight m3. The weight m1 of the load 38 is 20000 kg in this embodiment, the weight m2 of the trailer 18 is 7000 kg, and the weight m3 of the tractor 14 is 8000 kg.

[0036] Based on the weight m1 of the load 38 and the weight m2 of the trailer 18 , a vertical load force F of approximately 70 kN each is applied. L1Acting on the three rear axles 24, 26, 28 of the saddle trailer 18. Based on the weights m2 and m3, the vertical load force F of about 80 kN L2 Acting on the drive axle 22 of the tractor 14, and the steering axle 20 of the tractor 14 must also support the remaining vertical load force F of about 60 kN L3 .

[0037] During a one-time deceleration process 40 (so-called single adaptive braking event), the speed is approximately 1.0 m / s. 2 Negative acceleration a v The deceleration force F of 7 kN is applied to each of the three rear axles 24, 26, 28 of the trailer 18 during the one-time deceleration process 40. v1 The deceleration force F on the drive axle 22 of the tractor 14 V2 In this one-time deceleration process 40 , approximately 8 kN, whereas the steering axle 20 in the known motor vehicle 10 must also apply a deceleration force F of 6 kN. V3 .

[0038] In contrast, Figure 2 The forces acting on the motor vehicle according to the invention during a deceleration process during recuperation operation when the lifting axle is raised are shown schematically.

[0039] The motor vehicle 50 shown here is also designed as a two-section saddle tractor 52, which has a tractor 54 and a saddle trailer 56. The tractor 54 has a coupling point 58 for articulating the saddle trailer 56. Alternatively, the motor vehicle 50 can also be designed as a single-section truck (box truck) or a two-section truck, including a truck with a trailer. The motor vehicle 50 moves on a substantially horizontal track 60 at a speed v1, as shown by arrow 62.

[0040] Here, the tractor 54 also has a steering axle 64 and a rear axle 66 or drive axle arranged therebehind and drivable, which can be driven, for example, by an internal combustion engine (not shown) of the tractor 54. Alternatively, the tractor 54 can have a hybrid drive of an internal combustion engine partially supported by an electric motor or a purely electric drive. Furthermore, a fuel cell drive of the tractor 54 is also possible.

[0041] In the case of a single-section motor vehicle (not shown), it has a chassis with a steering axle and at least one drive axle or rear axle arranged behind the steering axle. The drive axle can be driven at least in a supporting manner by means of at least one electric machine that can be operated as an electric motor and generator. In addition, there is a lifting axle arranged behind the drive axle.

[0042] But now back to the Figure 2 Motor vehicle 50: The steered axle 64 of the tractor 54 has two wheels here, of which only wheel 68 is shown and visible. This also applies to the wheels of the rear axle 66 of the tractor 54, of which only wheel 70 is shown and visible. The wheels of the steered axle 64 and rear axle 66 of the tractor 54, which are located behind the plane of the drawing, are shown in FIG. Figure 2 The wheels 70 of the rear axle 66 of the tractor 54 may be provided with double tires in the case of higher loads caused by the trailer 56 .

[0043] The trailer 56 has two drive axles 74, 76 in the region of its rear part 72, which can be driven at least in a supporting manner by means of at least one electric motor (not shown). In addition, the trailer 56 has a non-drive lifting axle 78 or lifting axle arranged behind the two drive axles 74, 76. In this case, the trailer 56 is designed as a so-called "drive trailer (e-Trailer)".

[0044] The two drive axles 74, 76 and the lifting axle 78 are combined and arranged here only as a triple axle group in the tail 72 area of ​​the saddle trailer 56. The drive axles 74, 76 and the lifting axle 78 each have two wheels, wherein only the wheels 82, 84 of the drive axles 74, 76 located in the plane of the drawing and the wheel 86 of the lifting axle 78 can be seen here. The wheels of the drive axles 74, 76 and the lifting axle 78 located behind the plane of the drawing cannot be identified. The wheels 82, 84 of the two drive axles 74, 76 and the wheels 86 of the lifting axle 78 can be designed as single tires or double tires or triple tires if necessary. The rear rear axle 66 or the drive axle of the tractor 54 can also be designed as a drive axle supported at least partially by an electric motor similar to the drive axles 74, 76 of the saddle trailer 56.

[0045] The trailer 56 has a load 90 loaded thereon, which has a weight m1. The trailer 56 has its own weight m2 when unloaded, while the weight of the tractor 54 is indicated using the reference numeral m3. The values ​​of the weights m1, m2, m3 mentioned are the same as those according to Figure 1 The same as the embodiment.

[0046] A powerful battery 92 is also arranged near the bottom of the trailer 56, which provides electrical energy to at least one motor for auxiliary drive. In addition, the trailer 56 also has a complex control and / or regulating device 94, which is implemented as a compact electronic controller 96 with at least one digital computing unit 98.

[0047] All axles of the motor vehicle 50 can be equipped with an air spring system (not shown). For this purpose, at least two air springs (not shown) are respectively assigned to the two drive axles 74, 76 and the lifting axle 78 of the saddle trailer 56 and the steering axle 64 and the rear axle 66 of the tractor 54.

[0048] In this embodiment, the lifting bridge 78 can be at least partially or completely lifted off and can be completely or partially lowered again onto it by means of two actuators 104, 106 assigned to the lifting bridge as part of a lifting device 110 of the lifting bridge 78 of the trailer 56 and actuated by the control and / or regulating device 94. The double arrow 108 indicates this lifting movement. Of course, it is also possible within the scope of the invention to use only a single actuator for lifting and lowering the lifting bridge 78, which is preferably arranged centrally on the lifting bridge 78 and acts on it with a regulating force when necessary.

[0049] The term "partial lifting of the lifting axle 78" means in the present context that the lifting axle 78 is only slightly lifted and thus only partially relieved of load. As a result, its wheels 86 still remain in contact with the roadway 60, but a reduced vertical force acts on the roadway. As a result of this process, the load of the wheels 82, 84 of the drive axles 74, 76 that are in contact with the roadway 60 can be variably set within a wide range of limits by means of the control and / or regulating device 94.

[0050] and Figure 1 Different from the simplified diagram, Figure 2 The position of the wheels 86 of the lifting bridge 78 completely standing on the roadway 60 is drawn in dashed outline. The wheels 86 of the lifting bridge 78 completely lifted off the roadway 60 are in Figure 2 The difference is shown by a solid line.

[0051] In accordance with Figure 2 In the illustration of FIG. 6 , in the case of a fully lowered lift bridge 78 with respect to the roadway 60 , the mechanical load forces F of substantially the same magnitude are L1 The load force F acting on the rear axle 66 also applies to the two drive axles 74, 76 driven at least in an electric motor-assisted manner and to the lifting axle 78 of the trailer 56. L2 and the load force F on the steering axle 64 of the tractor 54 of the saddle tractor 52 L3Due to the three weights m1, m2, m3 mentioned, three essentially static load forces F result under the action of gravity: L1 、F L2 、F L3 For the case where the motor vehicle 50 is equipped with an air spring system, these load forces F L1 、F L2 、F L3 For example, the pressures can be measured by means of pressure sensors respectively integrated in the air springs of the air spring system and their values ​​can be detected and processed by means of the control and / or regulating device 94 .

[0052] Here, for example, 1.0 m / s 2 Negative acceleration a v In the exemplary one-time deceleration process 112, the lifting bridge 78 is similar to Figure 1 When the vehicle is completely lowered onto lane 60 as shown, the deceleration force F v1 Basically, it acts on the drive axles 74, 76 and the lifting axle 78 of the saddle trailer 56. In addition, the two deceleration forces F V2 、F V3 Acting on the rear axle 66 or the steering axle 64 of the tractor 54. Also acting on Figure 2 The deceleration force F of the lowered lifting bridge 78 is shown in dashed lines in FIG. v1 Not drawn for a clearer overview.

[0053] In the case of a fully lifted lift bridge 78 of a saddle trailer 56 off the roadway 60, the same as in the case of a known motor vehicle 10 Figure 1 The example shown in the figure shows a different situation. The load force F is 50% larger in each case. L1 +50% acts on the wheels 82 , 84 of the two drive axles 74 , 76 that are in contact with the roadway 60 , since the two drive axles 74 , 76 have each already absorbed the load force F which is no longer borne by the lifting axle 78 L1 As a result, the traction of the wheels 82, 84 of the two drive axles 74, 76 of the saddle trailer 56 that are in contact with the roadway 60 is significantly increased. v During the deceleration process 112 described above, the deceleration force F v1 +50% acts on each of the two drive axles 74 , 76 .

[0054] exist Figure 2In the embodiment shown, it is also provided that the tractor 54 and the trailer 56 each have at least one inclination sensor 114, 116, which are also connected to the control and / or regulating device 94. For this purpose, the inclination sensors 114, 116 can be connected to the control and / or regulating device 94 via lines (not shown) or via a suitable data bus system or via other controllers (not shown here) for data transmission.

[0055] Preferably, a sensor is also present on each wheel 68, 70, 82, 84, 86 of the motor vehicle 50 to detect wheel slip. The sensors, preferably designed as rotational speed sensors, are each connected to the control and / or regulating device 94 in a suitable manner via lines (not shown) or the mentioned data bus system. For a clearer overview, only the sensor 120, in particular the rotational speed sensor 122, assigned to the second drive axle 76 of the trailer 56 is shown here, which also represents all the remaining sensors.

[0056] In normal driving operation of the tractor 52, the two drive axles 74, 76 of the trailer 56 are at least supported by at least one electric motor, which is itself fed with the electrical energy required for operation by a battery 92. Here, at least one electric motor is arranged near the wheel hub and is connected to the battery 92 via an electric line 100. The control and regulation of at least one electric motor (which supports the electric motor drive of the two drive axles 74, 76 of the trailer 56) can also be achieved by means of a control and / or regulating device 94.

[0057] During normal braking of the tractor 52, the regenerative mode is activated, and the electrical energy released during the generator mode of the at least one electric machine can be fed in a controlled manner by the control and / or regulating device 94 into the battery 92, for example, to extend the range of the motor vehicle 50. For situations where more intensive braking or emergency braking of the motor vehicle 50 is required, a mechanical and friction-based braking system (not shown) can be used in the regenerative mode.

[0058] The control and / or regulating device 94 is designed according to the invention such that when at least one electric machine is in activated regenerative operation and when wheel slip or traction loss occurs on wheels 82, 84 on at least one drive axle 74, 76 and / or on the lowered lift axle 78 of the trailer 56, the lift axle 78 is at least partially raised by means of actuators 104, 106. Subsequently, a load force F acting on the wheels 82, 84 of the two drive axles 74, 76, respectively, which are in contact with the roadway 60, is L1 The maximum increase is 50%. Thus, in the generator-type regenerative operation of the electric machine, the wheels 82, 84 of the two drive axles 74, 76 of the trailer 56 are prevented from slipping or slipping, so that the braking effect of the regenerative operation is increased and more electrical energy can also be fed into the battery 92.

[0059] In this case, the detection of possible slip on the wheels 82, 84 of the tractor 52 is preferably carried out by means of a rotation speed sensor 122 respectively assigned to the wheel, whose measured values ​​or data can be sent to the control and / or regulating device 94 for evaluation. Alternatively, the control and / or regulating device 94 can use digital data or analog measured values ​​of an existing anti-lock braking system of the motor vehicle 52 for this purpose, if necessary.

[0060] Furthermore, it is possible to detect by means of two inclination sensors 114, 116 connected to the control and / or regulating device 94, which are shown here by way of example, whether the tractor 50 is moving on a substantially horizontal or significantly inclined roadway 60. In this case, the lifting of the lifting bridge 78 may lead to an impairment of the mechanical braking effect of the tractor 52, which may be required in the recuperation mode, when the roadway 60 is too steep. Here, the arrangement of the first inclination sensor 116 on the tractor 54 and the arrangement of the second inclination sensor 114 on the trailer 56 may enable predictive slope detection in that a control command is output to the actuator 110 for completely lowering the lifting bridge 78 before the trailer 56 with the heavier load 90 passes the section of the roadway 60 with the predefined excessive slope.

[0061] When the method according to the invention is used, in a first method step a), it is checked by means of a control and / or regulating device 94 whether at least one electric machine of the at least supporting drive axle 74, 76 is operated as a generator in the regenerative mode so that braking energy recovery is activated on the trailer 56. In a second method step b), it is detected by means of the control and / or regulating device 94 whether a slip or a loss of traction relative to the roadway 60 occurs at least on the wheels 82, 84 of at least one drive axle 74, 76 of the trailer 56. In a third and final method step c), the lifting axle 78 of the trailer 56 is raised when the conditions of the two preceding method steps a) and b) are cumulatively met so that the wheels 82, 84 of at least one drive axle 74, 76 are loaded with an additional vertical load force.

[0062] Therefore, the vertical load force F acting on the two drive axles 74 and 76 is L1 Depending on how far the lift bridge 78 is lifted from the roadway 60, the lift can be increased by up to 50% (F L1+50%). Slip or traction loss of the wheels 82, 84 on the two drive axles 74, 76 can thus be avoided and the braking effect and the energy harvesting in the regenerative operation of the at least one electric machine of the trailer 56 can be increased. The detection of possible slip on the wheels 82, 84 of the two drive axles 74, 76, on the wheels of the lifting axle 78 and on the wheels of the steering axle 64 and the rear axle 66 of the tractor 54 is carried out by means of rotational speed sensors 122 respectively assigned to the wheels and connected to the control and / or regulating device 94. The digital data or analog measured values ​​transmitted by the rotational speed sensor 122 are numerically evaluated in real time by means of the control and / or regulating device 94 and the at least one actuator 104, 106 of the lifting device 110 of the lifting axle 78 is controlled accordingly with the result.

[0063] Furthermore, the control and / or regulating device 94 can detect the driving of the tractor 52 on a slope by means of the two inclination sensors 114, 116. This can prevent the lifting bridge 78 from being raised in the case of excessively steep slopes of the roadway 60, or the already raised lifting bridge 78 can be at least partially lowered back onto the roadway 60 by means of at least one actuator 104, 106 of the lifting device 110 in a manner controlled by the control and / or regulating device 94.

[0064] List of reference numerals (part of the description)

[0065] 10 Motor Vehicles (Prior Art)

[0066] 12 Saddle tractor

[0067] 14 Tractor

[0068] 16 Coupling point of tractor 14

[0069] 18 Saddle trailer for motor vehicle 10

[0070] 20 Steering axle of tractor 14

[0071] 22 Drive axle of tractor 14

[0072] 24 First rear axle of saddle trailer 18

[0073] 26 Second rear axle of saddle trailer 18

[0074] 28 Saddle trailer 18 third rear axle

[0075] 30 End area of ​​the trailer 18

[0076] 32 rear axle group of saddle trailer 18

[0077] 34 Lanes for motor vehicles 10

[0078] 36 Speed ​​in forward direction of travel, arrow

[0079] 38 Cargo on a saddle trailer 18

[0080] 40 Deceleration process of the motor vehicle 10

[0081] 50 Motor vehicle (according to the present invention)

[0082] 52 Saddle tractor

[0083] 54 Tractor

[0084] 56 Saddle trailer

[0085] 58 Coupling point of tractor 54

[0086] 60 Lanes for motor vehicles 50

[0087] 62 Speed ​​in forward direction, arrow

[0088] 64 Steering axle of tractor 54

[0089] 66 Rear axle of tractor 54

[0090] 68 Wheels of the steering axle of tractor 54

[0091] 70 Wheels of the rear axle of tractor 54

[0092] 72 The rear of the saddle trailer 56

[0093] 74 First drive axle of saddle trailer 56

[0094] 76 Second drive axle of saddle trailer 56

[0095] 78 Lifting bridge of saddle trailer 56

[0096] 82 Wheels of the drive axle 74 on the saddle trailer 56

[0097] 84 Wheels of the drive axle 76 on the saddle trailer 56

[0098] 86 Wheels of the lifting axle 78 on the saddle trailer 56

[0099] 90 Cargo on saddle trailer 56

[0100] 92 Batteries

[0101] 94 Control and / or regulating devices

[0102] 96 Compact Controller

[0103] 98 Digital computing unit

[0104] 100 Wire

[0105] 104 First actuator on lifting bridge 78

[0106] 106 Second actuator on lifting bridge 78

[0107] 108 Vertical movement of lift bridge 78, double arrow

[0108] 110 Lifting device

[0109] 112 Deceleration process of motor vehicle 50

[0110] 114 Tilt sensor on trailer 56

[0111] 116 Tilt sensor on tractor 54

[0112] 120 Sensors

[0113] 122 Speed ​​sensor

[0114] a v Negative acceleration, deceleration

[0115] m1 Cargo weight 38, 90

[0116] m2 Weight of saddle trailer 18, 56

[0117] m3 Weight of tractor 14, 54

[0118] F L1 Vertical load forces of axles 24, 26, 28

[0119] F L2 Vertical load force of axle 22

[0120] F L3 Vertical load force of axle 20

[0121] F L1 +50% vertical load force of axles 74, 76

[0122] F V1 Retarding force of axles 24, 26, 28; 74, 76, 78

[0123] F V2 Axle 22; 66 deceleration force

[0124] F V3 Axle 20; 64 deceleration force

[0125] v1 Initial speed of the motor vehicle 10;50

[0126] v2 Final speed of motor vehicle 10;50

Claims

1. A motor vehicle (50) for transporting goods (90) and / or persons on a roadway (60), the motor vehicle having at least one steering axle (64), at least one drive axle (74, 76) and at least one lifting axle (78), the lifting axle having at least one actuator (104, 106) for raising and lowering the lifting axle, wherein: The wheels (82, 84) of the at least one drive axle (74, 76) can be driven electrically at least in a supporting manner by means of at least one electric machine which can be operated as an electric motor and as a generator and can be used as a generator in a regenerative operation of the motor vehicle (50), wherein the at least one electric machine is connected to a battery (92) and to a control and / or regulating device (94) for controlling and / or regulating the electric motor and generator operation of the at least one electric machine and for controlling and / or regulating the operation of the at least one lifting axle (78), characterized in that the control and / or regulating device The regulating device (94) is connected to a sensor (120) for detecting wheel slip on a wheel (82, 84) of the at least one drive axle (74, 76), and the control and / or regulating device (94) is configured such that, when wheel slip occurs on at least one wheel (82, 84) of the at least one drive axle (74, 76), the control and / or regulating device can send a control command to at least one actuator (104, 106) of the lifting axle (78) during an activated regeneration operation in order to raise the lifting axle and thereby relieve the load on at least one wheel (86) of the lifting axle (78).

2. The motor vehicle according to claim 1, characterized in that The control and / or regulating device (94) is designed such that it can at least partially lift the non-driven lifting axle (78) and thereby at least partially relieve the load by sending a control command to at least one associated actuator (104, 106), so that an additional load force (F L1 ) can be variably adjusted.

3. A motor vehicle according to claim 1 or 2, characterized in that In order to detect slip by means of the control and / or regulating device (94), a sensor (120) designed as a rotational speed sensor (122) is assigned to at least each wheel (82, 84) of at least one drive axle (74, 76), by means of which the control and / or regulating device (94) is connected in a signal or data-based manner.

4. The motor vehicle according to claim 3, characterized in that The control and / or regulating device (94) is connected in a signal or data-based manner to at least one inclination sensor (114, 116), by means of which the inclination of a lane (60) on which the motor vehicle (50) is traveling can be determined.

5. The motor vehicle according to claim 3, characterized in that The motor vehicle is designed as a truck or as a tractor (52) having a tractor (54) and a trailer (56), wherein the truck or the trailer (56) can be driven at least in an assisting manner by means of the at least one electric machine.

6. A method for operating a motor vehicle (50) for transporting goods (90) and / or persons on a roadway (60), the motor vehicle having at least one steering axle (64), at least one drive axle (74, 76) and at least one lifting axle (78), the lifting axle having at least one actuator (104, 106) for raising and lowering the lifting axle, wherein: The wheels (84, 86) of the at least one drive axle (74, 76) can be electrically driven at least in a supporting manner by means of at least one electric machine that can be operated as an electric motor and as a generator and can be used in a drivable manner in a regenerative operation of the motor vehicle (50), wherein the at least one electric machine is connected to a battery (92) and to a control and / or regulating device (94) for controlling and / or regulating the electric motor and generator operation of the at least one electric machine and for controlling and / or regulating the operation of the at least one lifting axle (78), the method comprising the following method steps: a) checking whether the motor vehicle is in regenerative operation by operating the electric machine as a generator and transmitting electrical energy to a battery (92), b) detecting wheel slip on at least one drive axle (74, 76), and c) raising the driveless lifting bridge (78) when the conditions specified in each of the method steps a) and b) are met.

7. The method according to claim 6, characterized in that The load force (F) acting on the at least one drive axle (74, 76) L1 ) can be variably adjusted within a limit range by at least partially raising or lowering at least one drive-free lifting bridge (78).

8. The method according to claim 7, characterized in that At least one non-drive lift axle (78) is only lifted to such an extent that its wheels (86) are relieved of load to the greatest extent possible, but nevertheless remain in contact with the roadway (60).

9. The method according to any one of claims 7 to 8, characterized in that Wheel slip is measured by means of a rotational speed sensor (122) assigned to the control and / or regulating device (94), which is assigned to each wheel (82, 84) of the at least one drive axle (74, 76).

10. The method according to any one of claims 6 to 8, characterized in that With the aid of at least one inclination sensor (114, 116) associated with the control and / or regulating device (94), it is detected whether the inclination of the roadway for raising the lift bridge (78) can be utilized for regeneration operation.

11. A controller, configured as a control and / or regulating device (94), wherein: The control and / or regulating device is arranged in a motor vehicle (50) and is designed in such a way that a method according to any one of claims 6 to 10 can be carried out by means of it.

Images