Drive train, method for controlling a drive train, and motor vehicle

Abstract

The present invention relates to a drive transmission system comprising: a drive motor; a driven vehicle axle (5), which is a rear axle; a vehicle transmission (2), which has a transmission stage and is used to transmit a driving force to the vehicle axle, the transmission stage can be switched by means of a transmission controller (4), and the vehicle transmission can also be switched to a neutral position by means of the transmission controller; a motor controller (3), the drive motor can be operated in a motor operation mode and a neutral mode by means of the motor controller. The motor controller and the transmission controller are connected to each other by at least two control lines, and the control lines are used to transmit control instructions between these controllers. The motor controller can transmit the control instructions to the transmission controller via at least one control line, so that the transmission controller switches the vehicle transmission to a neutral position. Redundant monitoring of the drive motor and / or the vehicle transmission is achieved. The present invention also relates to a method for controlling a drive transmission system and a motor vehicle comprising the drive transmission system.

Description

Technical Field

[0001] The invention relates to a drive transmission system. Background Art

[0002] DE 10 2018 116 586 A1 discloses a hybrid drive train in which a rear axle can be driven by means of a first drive machine via a shiftable transmission.

[0003] In a drive train for a motor vehicle having a driven rear axle, in particular a rear axle driven by an internal combustion engine, certain regulations, in particular ISO 26262 “Road vehicles - Functional safety”, require that certain components meet prescribed safety standards, in particular safety standards relating to functional safety. Summary of the invention

[0004] The present invention proposes a drive train which meets the prescribed requirements in a simple manner and enables efficient vehicle propulsion.

[0005] This object is achieved by a drive train according to the invention, a method according to the invention for controlling a drive train and a motor vehicle according to the invention having such a drive train.

[0006] The object is achieved by a drive train, which comprises at least one drive motor, which is configured to drive a motor vehicle;

[0007] and the drive train comprises a drivable axle, which is designed as a rear axle and is configured to transmit the driving force of at least one drive motor to a road surface;

[0008] and the drive train comprises a vehicle transmission having at least one transmission stage and being designed to transmit a driving force to a driven axle, the at least one transmission stage being shiftable in at least one operating mode of the drive train by means of a transmission controller, and the vehicle transmission being shiftable by means of the transmission controller in addition to the at least one transmission stage into a neutral position in which a transmission output shaft is freely rotatable relative to a transmission input shaft;

[0009] Furthermore, a motor controller is provided for controlling the drive motor, by means of which the drive motor can be operated at least in a motor operating mode and in a neutral mode, in which the drive motor can rotate without torque;

[0010] The motor controller and the transmission controller are interconnected by at least two control lines, the control lines being configured to transmit control instructions between the motor controller and the transmission controller; and

[0011] - redundant monitoring of the vehicle transmission is possible not only by the transmission controller but also by the motor controller, wherein the motor controller is able to detect a transmission fault so that the motor controller is able to transmit a control command via at least one of the two control lines to the transmission controller so that the transmission controller switches the vehicle transmission into a neutral position; and / or

[0012] - Redundant monitoring of the drive motor can be achieved not only by the motor controller but also by the transmission controller, wherein the transmission controller can detect a motor fault so that the transmission controller can transmit a control command to the motor controller via at least one of the two control lines so that the motor controller switches the drive motor into a neutral mode.

[0013] The object is also achieved by a method for controlling a drive transmission system of the present invention, wherein at least one operating parameter of a vehicle transmission is monitored by at least one monitoring device, and a transmission fault is determined when it is identified that the monitored operating parameter deviates from a rated value, characterized in that the transmission fault is determined by a motor controller, and the motor controller outputs a control command to the transmission controller via at least one of two control lines, so that the transmission controller switches the vehicle transmission to a neutral position.

[0014] The object is also achieved by a method for controlling a drive transmission system of the present invention, wherein at least one operating parameter of a drive motor is monitored by at least one other monitoring device, and a motor fault is determined when a deviation of the monitored operating parameter from a rated value is detected, characterized in that the motor fault is determined by a transmission controller, and the transmission controller outputs a control command to a motor controller via at least one of two control lines, so that the motor controller switches the drive motor to a neutral mode.

[0015] In the sense of the present invention, a drive train with a switchable vehicle transmission, a driven rear axle and at least one drive machine can be understood as a drive train for a motor vehicle, in particular for a passenger car, wherein at least the at least one drive machine is used alone or together with at least one other drive machine to drive the motor vehicle on the rear axle. In addition, the drive power transmitted from the at least one drive machine is transmitted to the rear axle by means of a switchable vehicle transmission, which has at least one switchable transmission ratio, the so-called gear. Therefore, in such a drive train, the transmission of the driving force can be realized at least through one transmission stage, which can be activated and thus switched by the transmission controller. In the sense of the present invention, an activated transmission stage can be understood as a transmission ratio / transmission stage through which the driving force can be transmitted by the vehicle transmission. In other words, if the at least one transmission stage is not activated, the transmission of the driving force can be realized by the vehicle transmission with another transmission stage, or the vehicle transmission is preferably placed in a neutral position so that the driving force is not allowed to be transmitted by the vehicle transmission.

[0016] In particular, the drive train can be designed as a so-called hybrid drive train (internal combustion engine and electric drive motor) or as an electric drive train with at least one electric drive motor, a so-called pure electric vehicle (BEV). In addition to the electric drive motor and the internal combustion engine, the proposed drive train can preferably also have further drive machines.

[0017] A driven axle in the sense of the invention is understood to be a device for transmitting a driving force provided by at least one of the above-mentioned drive machines to a road surface and for transmitting a steering force to the road surface. In addition, the driven axle is designed as a rear axle. Preferably, the motor vehicle has a main driving direction (forward driving direction) and the driven rear axle is arranged at the rear of the motor vehicle with reference to the main driving direction. In addition to the driven axle, further driven axles can also be provided, so-called all-wheel drive, or the motor vehicle can have only the proposed driven axle, so-called rear-wheel drive.

[0018] A vehicle transmission of a drive train is understood within the meaning of the present invention to be a transmission device for transmitting a driving force provided by at least one of the above-mentioned drive machines, preferably an internal combustion engine, and for providing different, preferably discrete transmission ratios, so-called gears, when transmitting this driving power. Preferably, the vehicle transmission is designed as a vehicle transmission that is automatically or automatically shifted at least temporarily or permanently, regardless of its design.

[0019] In addition, such a vehicle transmission has at least one, preferably a plurality of different transmission steps, so-called gears, for transmitting driving force from the internal combustion engine to the driven axle. The neutral position of the vehicle transmission is not to be understood as a gear or transmission ratio in the sense described above, since in the neutral position no driving force can be transmitted by the vehicle transmission.

[0020] In a vehicle transmission, the neutral position can also be formed by decoupling the drive machine, in particular if the transmission output shaft is at least approximately free to rotate when the drive machine is decoupled.

[0021] Preferably, the vehicle transmission is designed such that the vehicle transmission has at least one transmission step and further preferably, the vehicle transmission can be switched automatically or automatically by a transmission control unit temporarily, in particular in one of a plurality of operating modes, or preferably in all operating modes and thus permanently. Preferably, the one transmission step is understood to be a shiftable transmission step, wherein the vehicle transmission can be switched by the transmission control unit between neutral and the at least one transmission step or between the at least one transmission step and at least one further transmission step. Such vehicle transmissions are known from the prior art with regard to their design, in particular as dual clutch transmissions, as automatic transmissions (which are in particular designed as planetary gear transmissions with one or preferably a plurality of planetary gear sets), or as automated stepless transmissions, in particular as manual transmissions.

[0022] Furthermore, such a vehicle transmission also has a so-called neutral position, which is also colloquially referred to as neutral gear or neutral state of the vehicle transmission. In the neutral position of the vehicle transmission, at least the transmission output shaft can rotate freely relative to the vehicle transmission, so that no drive force can be transmitted via the vehicle transmission. A transmission output shaft is to be understood in particular as a transmission shaft, via which the drive force is output from the vehicle transmission, as long as the vehicle transmission transmits a drive force, in particular the drive force of at least one drive machine.

[0023] Furthermore, a motor controller, preferably a so-called inverter, is provided for controlling the drive motor. Preferably, the drive motor can be operated at least in a motor operating mode by means of the motor controller, wherein the drive motor outputs a drive power (speed, torque) in the motor operating mode. Furthermore, the drive motor can be operated by the motor controller in a neutral mode or can be placed in a neutral mode, wherein the drive motor, or a driven shaft of the drive motor, can rotate without torque for outputting the drive power (speed, torque), in particular in the neutral mode.

[0024] It is proposed that the motor controller and the transmission controller are connected to each other via at least two control lines, preferably mutually redundant control lines, which are designed to transmit control commands between the two controllers. Furthermore, the motor controller can transmit control commands to the transmission controller via at least one of the two control lines or via both control lines, so that the transmission controller switches the vehicle transmission into a neutral position.

[0025] The motor controller is designed in particular for monitoring and controlling the drive motor, but in particular also for monitoring the vehicle transmission. In predefined operating situations, faults in the vehicle transmission can be inferred via this monitoring function. In particular, when the vehicle transmission is stuck or when there is high internal friction in the vehicle transmission, the current consumption at the motor controller can exceed a threshold value. In particular, when such a threshold value is reached or exceeded, the motor controller can control the transmission controller so that the transmission controller switches the vehicle transmission into its neutral position. In particular, by means of this monitoring possibility and the control of the transmission controller by the motor controller, the vehicle transmission can be indirectly switched into the neutral position by the motor controller and thus a redundant and therefore particularly reliable control of the drive train can be achieved.

[0026] In a preferred embodiment of the invention, in the proposed drive train, a control command can be transmitted from the transmission controller to the motor controller via at least one of the two control lines, preferably via both control lines. In particular, with the aid of this control command, the drive motor can be switched into neutral mode by the transmission controller via the motor controller. In other words, the drive motor can thus be switched into neutral mode indirectly by the transmission controller. In addition, the transmission controller can monitor specific operating parameters, which can infer faults in or on the drive motor, and with the proposed drive train, a redundant control of the drive train can be achieved, and in particular, a particularly reliable operation of the drive train can thus be achieved.

[0027] Furthermore, a method for operating a drive train and therefore also a drive train operated using the method explained below is proposed.

[0028] The method for operating a drive train comprises in particular the following method steps:

[0029] - Determine transmission faults, in particular by means of the motor controller;

[0030] - Transmission faults are transmitted, in particular to the transmission controller; and

[0031] - switching the vehicle transmission into a neutral position, in particular by means of a transmission control.

[0032] Preferably, the transmission fault is determined by the motor controller and is therefore determined in particular in addition to the transmission controller, or the method steps required for determining the transmission fault are preferably executed on the motor controller and / or the transmission controller. Thus, the proposed method enables redundant monitoring of the vehicle transmission not only by the transmission controller but also in addition by the motor controller. In particular, the redundant monitoring of components increases operational safety.

[0033] A number of potential transmission faults and methods for determining these are known, in particular torque values / speed values, temperatures and / or noises can be recorded on the vehicle transmission by suitable sensors and evaluated in the motor control unit or in the transmission control unit. In particular, by such a concept of the drive train, the vehicle transmission is redundantly monitored by the transmission control unit and the motor control unit, and by using the two controllers that are already present, a safe and, on the one hand, economical operation of the drive train can be achieved.

[0034] In a preferred embodiment, the method for operating a drive transmission comprises the following method steps: determining a fault in the drive motor, in particular by means of a transmission controller; transmitting the fault, in particular to a motor controller; and switching the drive motor into a neutral mode, in particular by means of a motor controller.

[0035] Preferably, the failure of the drive motor is determined by a transmission controller as an additional or alternative to the motor controller, or the method steps required for determining the failure of the drive motor are preferably executed on the motor controller and / or the transmission controller. The proposed method thus makes it possible in particular to implement redundant monitoring of the drive motor not only by the transmission controller but also by the motor controller. In particular, redundant monitoring of components increases operational safety.

[0036] A number of potential drive motor faults and methods for determining them are known, in particular torque values, temperature, current values ​​or voltage values ​​and / or noises can be recorded at the drive motor by suitable sensors. In particular, by such a concept of the drive train, the drive motor is redundantly monitored by a transmission controller and an electric machine controller, and by using two controllers that are already present, a safe and, on the one hand, economical operation of the drive train can be achieved.

[0037] Furthermore, a motor vehicle is proposed, which comprises a drive train of the aforementioned design and preferably of the aforementioned operating mode. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Individual features and embodiments of the invention are explained in more detail below with reference to the accompanying drawings, in which:

[0039] Figure 1 A first specific embodiment of the proposed drive train is shown as a hybrid drive train;

[0040] Figure 2 A second specific embodiment of the proposed drive train is shown as a hybrid drive train. DETAILED DESCRIPTION

[0041] Figure 1 A transversely configured drive train for a motor vehicle is shown in the form of a hybrid drive train, comprising a driven rear axle 5 and a steerable front axle 6. In a transversely configured hybrid drive train, an internal combustion engine 1 is arranged transversely to a forward driving direction 9 in the motor vehicle.

[0042] In the forward driving direction 9, a driven rear axle 5 is located at the rear of the motor vehicle and a steerable front axle 6 is located at the front. Two driven wheels 7 are arranged on the rear axle 5 and are provided for transmitting driving forces to the road surface. Two steerable front wheels 8 are arranged on the front axle and are provided for transmitting steering forces.

[0043] The driving force transmitted by the driven wheels 7 is provided by the internal combustion engine 1 and / or a drive motor which is structurally integrated into the vehicle transmission 2. For controlling and monitoring the drive motor, a motor controller 3 designed as an inverter is provided. For controlling and monitoring the vehicle transmission 2, a transmission controller 4 is provided.

[0044] The two controllers 3 and 4 are connected to one another via two control lines 10 and 11 , in particular control lines that are redundant with one another.

[0045] The invention here follows the basic principle of preventing excessive deceleration at the rear axle 5 in the event of a fault, here a fault in the drive motor or in the vehicle transmission 2, by means of redundant and mutual monitoring of the transmission controller and the motor controller (i.e. the power electronics / inverter for controlling the drive motor).

[0046] In principle, at least two situations are conceivable, which show how advantageously such mutual monitoring of the control units 3, 4 works. Situation 1: A transmission fault occurs, which is detected by the motor control unit 3. In this fault situation (transmission fault), the vehicle transmission 2 or the transmission control unit 4 is preferably switched to a de-energized state, and the vehicle transmission 2 is thus preferably switched to a neutral position. In particular, by means of this control, the transmission output torque, i.e. the torque of the vehicle transmission 2 acting on the driven rear axle 5, is reduced below a threshold value and preferably at least substantially to zero.

[0047] Case 2: A fault occurs on the drive motor, a so-called drive motor fault. In this fault case (drive motor fault), the motor controller (especially as a power electronic device or inverter) is preferably switched to a currentless state, and the torque output by the drive motor, the so-called drive motor torque, therefore drops below a threshold value and preferably at least substantially to zero.

[0048] In order to operate the hybrid drive train in the proposed manner, the motor controller and the transmission controller are connected to one another via a communication interface which has two control lines 10 and 11 .

[0049] In the proposed invention, the motor controller and the transmission controller assume a complementary function (redundancy) for mutual monitoring of safety functions.

[0050] exist Figure 2 The drive train described in the invention is designed as a hybrid drive train and is similar in structure to the drive train described in the invention. Figure 1 The hybrid drive train described in FIG. 1 differs in that the internal combustion engine 1 is oriented longitudinally with respect to the forward driving direction 9. In terms of function, the two drive trains ( Figure 1 and Figure 2 ) correspond to each other.

[0051] Reference numerals list

[0052] 1 Internal combustion engine

[0053] 2 Vehicle transmission with drive motor

[0054] 3 Motor Controller

[0055] 4 Transmission Controller

[0056] 5. Driven rear axle

[0057] 6 Non-driven front axle

[0058] 7 Driven rear wheels

[0059] 8 Steerable front wheels

[0060] 9 Forward driving direction

Claims

1. A drive train, comprising at least one drive motor, wherein the drive motor is configured to drive a motor vehicle; The drive train comprises a drivable axle (5), which is designed as a rear axle and is configured to transmit the driving force of at least one drive motor to a road surface; The drive train comprises a vehicle transmission (2), which has at least one transmission stage and is designed to transmit a driving force to a driven axle (5), wherein the at least one transmission stage can be switched in at least one operating mode of the drive train by means of a transmission controller (4), and the vehicle transmission (2) can be switched by means of the transmission controller (4) in addition to the at least one transmission stage into a neutral position, in which the transmission output shaft can rotate freely relative to the transmission input shaft; Furthermore, a motor controller (3) is provided for controlling the drive motor, by means of which the drive motor can be operated at least in a motor operating mode and in a neutral mode, in which the drive motor can rotate without torque. It is characterized in that The motor controller (3) and the transmission controller (4) are connected to each other via at least two control lines (10, 11), wherein the control lines are configured to transmit control instructions between the motor controller (3) and the transmission controller (4); and - redundant monitoring of the vehicle transmission can be achieved not only by the transmission controller but also by the motor controller, wherein the motor controller (3) can detect a transmission fault so that the motor controller (3) can transmit a control command via at least one of the two control lines (10, 11) to the transmission controller (4) so ​​that the transmission controller (4) switches the vehicle transmission into a neutral position; and / or - Redundant monitoring of the drive motor can be achieved not only by the motor controller but also by the transmission controller, wherein the transmission controller (4) can detect a motor fault so that the transmission controller (4) can transmit a control command to the motor controller (3) via at least one of the two control lines (10, 11) so that the motor controller (3) switches the drive motor into a neutral mode.

2. A method for controlling a drive train according to claim 1, in, At least one operating parameter of a vehicle transmission is monitored using at least one monitoring device, and a transmission fault is determined when the monitored operating parameter is identified to deviate from a rated value. It is characterized in that the transmission fault is determined by a motor controller, and the motor controller outputs a control command to the transmission controller via at least one of two control lines, so that the transmission controller switches the vehicle transmission to a neutral position.

3. A method for controlling a drive train according to claim 1, in, At least one operating parameter of the drive motor is monitored using at least one other monitoring device, and a motor fault is determined when the monitored operating parameter deviates from a rated value. It is characterized in that the motor fault is determined by a transmission controller, and the transmission controller outputs a control command to the motor controller via at least one of two control lines, so that the motor controller switches the drive motor to a neutral mode.

4. A motor vehicle comprising a drive train according to claim 1.

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