Control unit and method for controlling a brake system

Abstract

The invention relates to a control unit (10) for a motor vehicle (1) with a drive (2) for generating a driving torque for the motor vehicle (1), with a step-up gear mechanism (3) for stepping up the driving torque and with a brake device (4) for generating a braking torque on at least one driven wheel (5) of the motor vehicle, wherein the drive (2) is actuated in response to a pedal signal P. The control unit (10) has a detection unit (11) for detecting a value GB of a speed limit and a comparison unit (12) for comparing an actual value Gl of a vehicle speed with the value of the speed limit, wherein the control unit (10) is designed, in a first mode, to receive a signal ST of a thermal management system (6) of the motor vehicle (1 ) and, if the signal ST indicates a heat requirement and if the value GB of the speed limit is less than the actual value Gl of the vehicle speed, to trigger activation of the brake device (4) and to conduct heat produced at the brake device (4) to the thermal management system (6).

Description

[0001] Control unit and method for controlling a braking system

[0002] The invention relates to a control unit for controlling a braking system and a motor vehicle with such a control unit.

[0003] In the area of ​​private and public motor transport, increasingly stringent emissions standards are being enacted for environmental reasons. Furthermore, a constantly growing number of road users requires significantly more efficient vehicles in terms of vehicle control to enable predictive driving, avoid accidents, and conserve available resources.

[0004] State-of-the-art vehicles include conventional vehicles with combustion engines, hybrid vehicles, fully electric vehicles (BEVs), and vehicles with other drive systems, as well as autonomous vehicles with various drive systems. These vehicles feature numerous assistance systems, sensors, cameras, internet connections, and GPS. It is already possible to automatically limit the speed of a vehicle by manually entering a specific maximum speed by the driver. Once such a maximum speed is set, the driver can only accelerate the vehicle up to this speed by pressing the accelerator pedal. Once the preset maximum speed is reached, the driver cannot achieve any further acceleration by further pressing the accelerator pedal.In other words, an acceleration signal associated with a pedal position is, so to speak, "ignored" beyond a certain pedal position. However, the maximum speed can still be exceeded because there is no active system to monitor the speed. Therefore, it is an object of the invention to provide a control unit and a motor vehicle with such a control unit that provides an efficient method for limiting the speed.

[0005] This object is achieved according to the invention by a control unit according to claim 1 and a motor vehicle according to claim 5. Preferred embodiments are specified in the subclaims.

[0006] Within the scope of the invention, a control unit for a motor vehicle is specified, comprising a drive for generating a drive torque for the motor vehicle, a transmission gear for transmitting the drive torque and a braking device for generating a braking torque on at least one driven wheel of the motor vehicle, wherein the drive is actuated in response to a pedal signal P.The control unit has a detection unit for detecting a speed limit value GB and a comparison unit for comparing an actual vehicle speed value Gl with the speed limit value. In a first mode, the control unit is designed to receive a signal ST from a thermal management system of the motor vehicle and, if the signal ST indicates a heat requirement and if the speed limit value GB is lower than the actual vehicle speed value Gl, to trigger activation of the braking device and to conduct heat generated at the braking device to the thermal management system. Such a thermal management system, as is generally used in motor vehicles in the prior art, detects a heat requirement of various vehicle components and controls corresponding heat flows via thermal fluids and, if appropriate, heat exchange devices.The result output by the comparison unit can be processed in a processing unit of the control unit. The control unit according to the invention is thus designed to automatically activate the braking unit when a speed limit value GB is lower than the actual vehicle speed value Gl and when, at the same time, the motor vehicle's thermal management system indicates that heat is required, for example, to heat the vehicle and / or a vehicle battery to create optimal operating conditions.

[0007] According to a preferred embodiment, the control unit can be designed to deactivate the pedal signal P when the signal ST of the

[0008] thermal management system does not indicate a heat requirement and if the value GB of the speed limit is less than the actual value Gl of the

[0009] Vehicle speed. According to this embodiment, no active braking is initiated if the thermal management system indicates no heat requirement. Instead, further acceleration of the motor vehicle is prevented when a driver presses a pedal. In other words, in this case, the pedal signal, which conventionally triggers acceleration by activating the drive, is ignored by the processing unit, and no braking is initiated. In this way, the braking system can be protected if there is no heat requirement, and the vehicle speed is limited solely by preventing further acceleration.

[0010] In an alternative embodiment, the control unit can be designed to trigger activation of the braking device and to dissipate the heat generated by the braking device to the outside if the signal ST of the thermal management system indicates no heat requirement and if the value GB of the speed limit is less than the actual value Gl of the vehicle speed. In this embodiment, an active braking process therefore takes place even if there is no need for heat supply on or in the motor vehicle. A braking process is therefore always initiated by the control unit when the value GB of the speed limit is less than the actual value Gl of the vehicle speed. The heat energy generated during the braking process can be dissipated, for example, by a heat exchanger. If necessary, the two aforementioned embodiments can also be combined.This means that if the value GB of the speed limit is less than the actual value Gl of the vehicle speed and if the signal ST of the thermal management system does not indicate a heat requirement, the control device initiates a braking process and deactivates or ignores the pedal signal P.

[0011] The control unit can be configured so that the first mode can be activated manually. In other words, the driver is given a choice of the first or "predictive" driving mode, which they can activate, for example, by pressing a button. In this first mode, the legally prescribed speed is maintained constant by actively engaging the complementary brake, and the excess energy is converted into heat in the complementary brake.

[0012] The invention also relates to a motor vehicle which has a drive for generating a drive torque for the motor vehicle, a transmission gear for transmitting the drive torque and a braking device for generating a braking torque on at least one driven wheel of the motor vehicle, a pedal which can be actuated by a driver, wherein the drive is actuated in response to a pedal signal P, and a thermal management system for determining a heat requirement in the motor vehicle and for distributing a heat transport fluid in a line system depending on the heat requirement, wherein a control unit according to at least one of the preceding embodiments has.

[0013] The motor vehicle can be designed, for example, as a hybrid vehicle or as a purely electric vehicle. The motor vehicle is realized, for example, as a passenger car, minibus, small truck, or the like. In particular, the vehicle is designed as a road vehicle and / or is registered and / or suitable for road traffic. For example, the vehicle can reach a top speed of more than 80 km / h, preferably more than 120 km / h, and in particular more than 140 km / h.

[0014] The transmission for transmitting the drive torque in a drive train of the motor vehicle is connected downstream of the drive. Particularly preferably, a transmission is provided from high to low speed, colloquially also referred to as gear reduction. The transmission is designed to output a transmitted drive torque based on the drive torque from the electric drive motor in the direction of the at least one driven wheel of the vehicle. For example, the transmission has a transmission output via which the transmitted drive torque is output in the direction of the at least one driven wheel of the vehicle. Optionally, a distribution transmission, in particular a differential, and / or a summation transmission for combining the transmitted drive torque with other drive torques is connected downstream of the transmission.

[0015] Within the scope of the invention, a braking device for generating a braking torque on at least one driven wheel is part of the motor vehicle. The braking device is designed, in particular, as a dynamic braking device and / or as a braking device for actuation during driving operation of the vehicle. In particular, the braking device is not designed as a parking brake, or at least not as a pure parking brake.

[0016] One embodiment of the invention provides that the drive of the motor vehicle is designed as an electric motor. The drive thus comprises an electric drive unit, i.e., an electric motor, for generating the drive torque for the vehicle. It can be provided that the electric motor forms the sole traction unit for the motor vehicle. Alternatively, the motor vehicle may also comprise additional traction units, for example, additional electric drive units and / or an internal combustion engine, for generating the drive torque.

[0017] The electric motor can be assigned to a single driven wheel of the vehicle and / or configured as a single-wheel drive. Alternatively, the electric motor is assigned to two driven wheels, preferably a common axle, and / or configured as a single electric axle. In other embodiments, the electric motor can also be assigned to all driven wheels and / or wheels of the vehicle and / or configured as an all-wheel drive.

[0018] In the motor vehicle according to the invention, a braking torque path extends between the braking device and the at least one driven wheel, wherein the braking torque path runs via the transmission gear. Thus, the braking torque path extends from the braking device to the at least one driven wheel. The braking torque is thus generated by the braking device and transmitted to the at least one driven wheel via the braking torque path.

[0019] The braking device can be arranged upstream of the transmission in the braking torque path. The braking device is thus located in a section in which the drive torque has not yet been transmitted by the transmission. In the preferred embodiment, the speed of the braking device is higher than the speed at the transmission output and / or at the driven wheel. The braking device is therefore particularly preferably arranged close to the drive engine and not close to the wheel. This position leads to two possible advantages: The braking device is arranged in a section in which the speed has not yet been transmitted by the transmission and is therefore higher than at the driven wheel and / or at the transmission output. This reduces the braking torque to be applied by the braking device and allows other braking systems to be used instead of a dry friction brake.

[0020] In a preferred embodiment, the electric motor has a rotor shaft, wherein the braking device is connected to the rotor shaft in a braking standby state or permanently rotationally coupled, preferably non-rotatably. Alternatively or additionally, it is claimed that the braking device is operated at the engine speed of the drive machine.

[0021] In a further preferred embodiment of the invention, the braking device is designed as a friction braking device. The friction braking device implements the braking effect, in particular, through friction, specifically through solid-body friction, wherein two braking partners can be brought into frictional contact. The braking partners are designed, in particular, as solid bodies.

[0022] The friction brake device comprises, for example, a temperature control fluid for lubricating and / or cooling the friction brake device. The cooling can be designed, in particular, as external cooling, wherein the temperature control fluid cools the friction brake device externally and, in particular, is arranged and / or runs without contact with the friction surfaces of the braking partners. Alternatively, the temperature control fluid is also designed for internal lubrication and / or cooling of the friction brake device, such that the braking partners, in particular the friction surfaces of the braking partners, are in physical contact with the temperature control fluid and / or the friction surfaces of the braking partners are in physical contact with the temperature control fluid and / or the friction brake device is designed to be wet or wet-running.In particular, the friction brake device can be designed as a wet-running multi-disk brake, with the multi-disk brake, in particular the brake discs, running in the tempering fluid for lubrication and / or cooling of the multi-disk brake. The tempering fluid can serve as a heat transfer medium to transfer the heat generated during braking, either directly or via a heat exchanger, to a unit such as a heat circuit for heating the interior of the motor vehicle or a vehicle battery. This occurs under the control of the motor vehicle's thermal management system. For this purpose, the thermal management system can be signal-linked to a heating system for a motor vehicle battery.

[0023] The motor vehicle according to the invention can furthermore have a service brake, wherein the braking device is designed as a complementary brake to the service brake and / or supplementary braking device to the service brake.

[0024] Preferably, the service brake in the vehicle is designed as a friction brake, in particular as a dry friction brake, in particular as a disc and / or drum brake.

[0025] Further features, advantages, and effects of the invention will become apparent from the following description of a preferred embodiment of the invention and the accompanying drawings. The drawings show:

[0026] Figure 1 is a schematic view of a motor vehicle which can be equipped with a control device according to the invention; and

[0027] Figure 2 is a diagram of a control device according to the invention.

[0028] With reference to the illustration in Figure 1, a motor vehicle is generally designated by the reference numeral 1. The motor vehicle 1 comprises a drive 2, which may, for example, be an electric motor. The electric motor here comprises a rotor shaft 2a, on which a braking device 4 is mounted, which may be rotationally fixedly coupled to the rotor shaft 2a. The braking device 4 is arranged here between the drive 2 and a transmission gear 3. In other words, the braking device 4 is located in front of the transmission gear 3 in a drive path which runs from the drive 2 to at least one driven wheel 5. The braking device 4 can, in particular, be a complementary brake which is present in addition to a service brake (not shown in the figure) of the motor vehicle 1.

[0029] The motor vehicle 1 also has a vehicle battery 9, which stores, for example, the electrical energy required to operate the drive 2.

[0030] A control unit 10 for the motor vehicle 1 shown in Figure 1 is schematically illustrated in Figure 2. The control unit 10 comprises a detection unit 11, which may, for example, be a camera designed to optically detect traffic signs and convert their meaning, such as a maximum permissible vehicle speed, into a digital signal. This digital signal is forwarded, as shown in the figure, to a comparison unit 12, which is also part of the control unit 10 according to the invention. In other words, in the present case, the detection unit 11 outputs the value GB of the speed limit to the comparison unit 12.

[0031] The comparison unit 12 is designed to compare the digital signal output by the detection unit 11, i.e., the speed limit value GB, with an actual vehicle speed value Gl. The actual vehicle speed value Gl is provided, for example, by a speed measuring unit 14, as is common in every motor vehicle 1. If the actual vehicle speed value Gl is greater than the speed limit value GB, the comparison unit 12 sends a corresponding signal to a processing unit 13 of the control unit 10. The processing unit 13 also receives a signal from a thermal management system 6 of the motor vehicle 1.

[0032] If the signal of the thermal management system 6 indicates that there is a heat requirement at any point in or on the motor vehicle 1 , ie at a vehicle component, and therefore the temperature of a vehicle component should be increased, the processing unit 13 activates the braking device 4 (see Figure 1 ) of the motor vehicle 1 so that it carries out active braking and the motor vehicle

[0033] 1 brakes until the actual vehicle speed value Gl is equal to or less than the speed limit value GB. The waste heat generated during braking can be distributed according to the requirements indicated by the thermal management system 6.

[0034] List of reference symbols

[0035] 1 motor vehicle

[0036] 2 drive

[0037] 2a Rotor shaft

[0038] 3 transmission gears

[0039] 4 Braking device

[0040] 5 driven wheel

[0041] 6 Thermal management system

[0042] 9 Vehicle battery

[0043] 10 Tax system

[0044] 11 Recording unit

[0045] 12 Comparison unit

[0046] 13 Processing unit

[0047] 14 Speed ​​measuring unit

[0048] GB value speed limit

[0049] Gl actual value speed

[0050] P pedal signal

Claims

Patent claims 1. A control unit (10) for a motor vehicle (1) comprising a drive (2) for generating a drive torque for the motor vehicle (1), a transmission gear (3) for transmitting the drive torque, and a braking device (4) for generating a braking torque on at least one driven wheel (5) of the motor vehicle, the drive (2) being actuated in response to a pedal signal P, the control unit (10) comprising a detection unit (11) for detecting a value GB of a speed limit and a comparison unit (12) for comparing an actual value Gl of a vehicle speed with the value of the speed limit, characterized in that the control unit (10) is designed, in a first mode, to receive a signal ST of a thermal management system (6) of the motor vehicle (1), andif the signal ST indicates a heat requirement and if the value GB of the speed limit is less than the actual value Gl of the vehicle speed, to trigger activation of the braking device (4) and to conduct heat generated at the braking device (4) to the thermal management system (6).

2. Control unit (10) according to claim 1, characterized in that the control unit (10) is designed to deactivate the pedal signal P when the signal ST of the thermal management system (6) indicates no heat requirement and when the value GB of the speed limit is less than the actual value Gl of the vehicle speed.

3. Control unit (10) according to claim 1, characterized in that the control unit (10) is designed to do so when the signal ST of the thermal management system (6) indicates no heat requirement and when the value GB of the speed limit is smaller than the actual value Gl of the Vehicle speed, to trigger activation of the braking device (4) and to dissipate the heat generated at the braking device (4) to the outside.

4. Control unit (10) according to one of the preceding claims, characterized in that the first mode can be activated manually.

5. Motor vehicle (1), comprising a drive (2) for generating a drive torque for the motor vehicle (1), a transmission gear (3) for transmitting the drive torque and a braking device (4) for generating a braking torque on at least one driven wheel (5) of the motor vehicle, and a pedal (7) which can be actuated by a driver, the drive (2) being actuated in response to a pedal signal P, and a thermal management system (6) for determining a heat requirement in the motor vehicle (1) and for distributing a heat transport fluid in a line system as a function of the heat requirement, characterized in that it has a control unit (10) according to at least one of the preceding claims.

6. Motor vehicle (1) according to claim 5, characterized in that the drive (2) is designed as an electric motor or a combination of electric motor and internal combustion engine.

7. Motor vehicle (1) according to claim 6, characterized in that a braking torque path extends between the braking device (4) and the at least one driven wheel (5), the braking torque path running via the transmission gear (3).

8. Motor vehicle (1) according to one of the preceding claims 5 to 7, characterized in that the electric drive (2) has a rotor shaft (2a), wherein the braking device (4) is connected to the rotor shaft (2a) in a rotationally fixed manner.

9. Motor vehicle (1) according to one of the preceding claims 6 to 8, characterized in that the thermal management system (6) is provided with a heating system (8) for a motor vehicle battery (9).

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