Driving dynamics system for a vehicle having wheels, and method for adjusting a brake pressure

Abstract

1. The invention relates to a driving dynamics system for a vehicle having wheels (R1-R4), comprising: - a primary control unit (M-ECU) for detecting and / or generating steering commands and brake commands; - at least two hydraulically actuatable wheel brakes (RB1-RB4) which are each associated with one wheel (R1-R4); - at least one electrical traction motor having a traction-motor control unit, wherein the traction motor (TM1, TM2) is provided to drive at least one of the wheels (R1-R4), the primary control unit being communicatively connected to a traction-motor control unit in order to control the traction motor (TM1, TM2) to implement the steering commands and brake commands; - at least one (first) electrohydraulic pressure supply unit (BM1), wherein a brake-pressure adjustment valve in the form of a special solenoid valve (MV2k), which can in particular be shut tight, and an outlet valve (AV1-AV4) are associated with at least one of the hydraulically actuatable wheel brakes (RB1-RB4), wherein the driving dynamics system, in particular the primary control unit (M-ECU), is designed to relieve pressure from the at least one hydraulically actuatable wheel brake selectively via the associated outlet valve or via the special solenoid valve (MV2k).

Description

[0001] Driving dynamics system for a vehicle with wheels and method for adjusting a brake pressure

[0002] Designation

[0003] The present invention relates to a vehicle dynamics system (FDS) with a primary control unit or a central computer (M-ECU) according to the preamble of claim 1 and a method for adjusting a brake pressure.

[0004] State of the art

[0005] Since the market introduction of the anti-lock braking system (ABS), the traction control system (ASR), and the electronic stability program (ESP) in 1978, 1986, and 1995, brake pressure control systems for electrohydraulic brakes (EHB) based on the return flow principle with pre-pressure via a master brake cylinder have become established. In this system, pressure buildup, throttled by PWM, occurs via intake valves and pressure reduction via a time-controlled exhaust valve system. A valve block, electric motor, pump, accumulator chamber, eight solenoid valves (for ABS) or twelve solenoid valves (for ESP), pressure sensor, and electronic control unit (ECU) are typically combined in a single unit, and are installed spatially separate from the brake booster (BKV) in the engine compartment.

[0006] The most common system in existing vehicles on the market is the use of ABS / ESP motor-pump units in combination with vacuum brake boosters and vacuum pumps. So-called 2-box brake systems with an electro-hydraulic brake booster and a separate ESP unit (DE102012211278A1) and so-called 1-box brake systems with integrated brake booster and pressure modulation (EP1907253B1, DE102013222281A1) are standard in new vehicles.

[0007] The hydraulic design of the ESP unit with twelve solenoid valves as a pressure supply unit has not changed since its series introduction in 1995. However, a standardized interface (see VDA 360) has been specified for the interaction between the control unit of an electric brake booster and the control unit of the ESP unit for additional functions and for component protection of a rigid electromechanical brake booster. For certain functions, the control unit controls the ESP unit's solenoid valves for specific functions. DE102012211278A1 describes the control of valves and the ABS pump for regenerative braking.

[0008] The automotive industry is undergoing a significant transformation. In addition to the increasing market penetration of electric vehicles, various levels of automated driving (SAE Levels 2-5) are being implemented, with each level of autonomous driving increasing the redundancy requirements for the braking systems used (see ATZ article 3 / 2019 "Brake Boosters for Automated Driving").

[0009] In addition, centralized control of a vehicle with control units for chassis control (hereinafter referred to as "Vehicle Motion Control" or "VMC" or "Vehicle Chassis Control" or "VCC") is being introduced. This includes the electrohydraulic brake, electric traction motors™ on one or more axles of a vehicle, the electric power steering (EPS), and optionally also the damping. Synergies can be exploited through central control.

[0010] For the first time since 2020, the Formula E racing series will not use the "blending strategy" defined as standard in the 5th edition of the brake manual (see Chapter 19: "Regenerative Braking Systems") for regenerative braking with powerful electric traction motors. This strategy involves reducing the hydraulic braking torque by the braking torque of the electric traction motor. Instead, a braking torque is generated additively by an electric traction motor and the electro-hydraulic brake to shorten the time required to reach the locking braking torque / locking braking pressure (TTL). This shortens the braking distance by building up the braking torque as quickly as possible. Current limitations and problems of ABS / ESP systems according to the state of the art

[0011] A problem with current ABS / ESP braking systems with motor-pump units is the limited dynamic response for new functionalities, such as the automatic emergency brake (AEB). For this function, it is crucial to build up the brake pressure to the wheel-locking pressure (typical values ​​in car braking systems: 80–100 bar) in the shortest possible time. While the ABS / ESP braking system with its pump and electric brush motor reaches a pressure of 50 bar in 450 ms, single-box braking systems with a powerful brushless motor (DE102005063659B3) can reach the wheel-locking pressure of 80–100 bar in less than 150 ms. Short TTL times can reduce the braking distance by more than 5 meters at an initial speed of 65 km / h.

[0012] Every ABS / ESP braking system (ABS / ESP braking system with a motor-pump unit and a single-box) inherently features check valves. These are hydraulically connected in parallel to the inlet valves in the hydraulic lines to the wheel brakes for safety reasons. They ensure that the pressure in the wheel brakes is always automatically reduced. This means that if the pressure supply fails, no pressure remains in the wheel brakes. However, this technical solution makes a wheel brake circuit failure difficult or impossible to diagnose because it is unclear whether a check valve or the inlet valve is the cause of the wheel circuit failure. Consequently, in the event of a failure, an entire brake circuit with two wheel brakes must be deactivated.Therefore, diagonal brake circuit distribution (X-brake circuit) is the preferred distribution in the majority of vehicles, because in the event of a brake circuit failure, braking can still be achieved with a front brake with greater braking effect than a rear brake. The so-called "black-and-white" brake circuit distribution (II-brake circuit) is used in hybrid or electric vehicles. It has the disadvantage of poor braking effect in the event of a failure, but the advantage of easier implementation of control strategies for regenerative braking.

[0013] Furthermore, an ABS / ESP braking system with a motor-pump unit with pressure reduction via time-controlled outlet valves in the accumulator chamber has disadvantages in terms of braking distance control performance compared to the above-mentioned 1-box braking systems (cf. DE102013222281A1) with pressure reduction in the reservoir. This is because during pressure reduction the counterpressure in the accumulator chamber (up to 5 bar) limits rapid pressure reduction at low pressures. With ABS control on roads with low friction values ​​(snow and ice), this leads to a slow pressure reduction and the wheel speed drops during ABS control are therefore very long. This leads to a long braking distance. In some cases, ABS can only be controlled rudimentarily on roads with extremely low friction values ​​(ice). As a result, standard ABS / ESP systems have a further significant disadvantage in braking distance compared to the new standard set with 1-box braking systems due to poorer control performance, even in normal operation.

[0014] Object of the invention

[0015] The object of the invention is to provide an improved driving dynamics system, particularly in the form of multiple pressure supply units (a 2-box solution with two hydraulic pressure supply units connected in series, separate pressure regulators for each of the two wheel brakes). The system should preferably solve the aforementioned problems. The system should be small, reliable, precise, safe, and highly efficient.

[0016] The driving dynamics system should also meet the requirements of autonomous ferry operation (SAE Level 3, 4 with driver request detection via an e-pedal or SAE Level 5 without pedal with setpoint specification by a central computer) and new interfaces between brake modules and the control unit should be developed.

[0017] Pressure supply units among each other and / or brake module and central computer can be created.

[0018] Furthermore, the system should make it possible to offer driving dynamics control functions (ABS, ESP, EBV, ACC, AEB, Reku-Mgt) and wheel-individual braking torque interventions (BtS: Brake-to-Steer, BtTV: Brake-to-Torque Vectoring) efficiently by integrating at least one electric traction motor.

[0019] Solution of the invention

[0020] This object is achieved by the subject matter according to claim 1.

[0021] In particular, the object is achieved by a vehicle dynamics system for a wheeled vehicle, comprising: - a primary control unit for detecting and / or generating steering commands and braking commands;

[0022] - at least two hydraulically operated wheel brakes, each assigned to a wheel;

[0023] - at least one electric traction motor with traction motor control unit, wherein the traction motor is arranged to drive at least one of the wheels, wherein the primary control unit is communicatively connected to a traction motor control unit to control the traction motor to implement the steering commands and braking commands;

[0024] - at least one (first) electro-hydraulic pressure supply unit with o at least one electric motor-pump unit: o at least two connections for connecting the wheel brakes; o electrically actuated wheel brake pressure adjustment valves or brake pressure adjustment valves, and o a first secondary control unit; wherein at least one of the hydraulically actuated wheel brakes (RB1-RB4) is assigned a brake pressure adjustment valve in the form of a special solenoid valve (MV2k), in particular one that is resistant to closing, and an outlet valve, characterized in that the driving dynamics system, in particular the primary control unit (M-ECU), is designed to reduce pressure from the at least one hydraulically actuated wheel brake either via the assigned outlet valve or via the special solenoid valve (MV2k).

[0025] In the first variant, pressure reduction preferably occurs exclusively via the respective outlet valve. In the second variant, pressure reduction can occur exclusively via the respective special solenoid valve or simultaneously via the special solenoid valve and the outlet valve.

[0026] Furthermore, the task is solved by a driving dynamics system that includes:

[0027] - a primary control unit for detecting and / or generating steering commands and braking commands; - at least two hydraulically actuated wheel brakes, each assigned to a wheel;

[0028] - at least one electric traction motor with a traction motor control unit, the traction motor being arranged to drive at least one of the wheels, the primary control unit being communicatively connected to a traction motor control unit to control the traction motor to implement the steering commands and braking commands;

[0029] - at least one (first) electro-hydraulic pressure supply unit with o at least one electric motor-pump unit; o at least two connections for connecting the wheel brakes; o electrically actuated wheel brake pressure adjustment valves or brake pressure adjustment valves, and o a first secondary control unit;

[0030] - wherein at least one of the brake pressure adjustment valves comprises a special solenoid valve with an electromagnetic drive having a first excitation coil, via which a valve actuator or valve tappet can be adjusted between an open valve position and a closed valve position.

[0031] One inventive aspect is that the special solenoid valve has an additional force device comprising a permanent magnet and / or a second excitation coil and arranged to provide at least one retaining force acting on the valve actuator or the valve tappet. This measure preferably makes the special solenoid valves, which can be used as intake valves or wheel intake control valves, resistant to closing.

[0032] By designing the wheel brake circuit with non-closing wheel inlet control valves, the system according to the invention is significantly more fail-safe than prior art braking systems, and a braking system with wheel circuits (wheel-individual pressure control and / or supply) can be implemented instead of conventional brake circuits with multiple wheels (diagonal or black-and-white). For example, the failure of a wheel circuit can be diagnosed, and the failed wheel circuit can be separated from the pressure supply by closing an inlet valve. Thus, in the event of a failure of one (individual) wheel circuit, significantly improved deceleration can be achieved with the remaining three wheel circuits in the event of a fault, and yaw moment interventions can still be carried out on three wheels. Hereinafter, brake modules of a first pressure supply unit with special solenoid valves according to claim 1 are referred to as ESP-X.

[0033] The primary control unit can detect a steering and / or braking command, for example, via steering wheel sensors or force-displacement sensors on an electric brake pedal. However, the primary control unit can also be designed to generate independent steering and braking commands. This is necessary in the course of autonomous driving. Corresponding commands can also arise due to the implementation of a safety function (e.g., automatic emergency braking AEB). A steering command within the meaning of the present invention does not mean the specific intervention of a driver using the steering wheel. Instead, the present invention understands a steering command to be any instruction that relates to the vehicle moving in a specific direction and also includes trajectory control in autonomous driving operation. For example, this also includes a command that leads to a change in the yaw moment.Torque vectoring can also be implemented using appropriate steering and / or braking commands.

[0034] The (first) electrohydraulic pressure supply device can be an ABS / ESP unit. However, it should generally be understood as any unit that has a pressure generator, for example, in the form of the aforementioned motor-pump units, and provides the appropriate pressures at the corresponding connections. The pressure supply unit can also perform regulation and / or control functions. It can therefore be a pressure control module.

[0035] One aspect of the invention is that the special solenoid valve provides an additional retention force. This makes the special solenoid valve resistant to closing and allows high pressures to be released via this valve. In addition to the retention force, there can also be a restoring force that moves the valve actuator or valve tappet into an open valve position.

[0036] In one embodiment, the primary control unit can be designed to control the special solenoid valve of the first pressure supply unit, at least in a selected braking mode, such that pressure is released from the wheel brake assigned to the special solenoid valve when the special solenoid valve is open. Preferably, each special solenoid valve of the first pressure supply unit is assigned to a wheel brake. Due to the pull-tight design, the respective special solenoid valve can be used not only as an inlet valve, but also as a type of outlet valve. The pressure can be built up and released bidirectionally via the same special solenoid valve. This enables a (significantly) faster pressure reduction of the respectively assigned wheel brake because pressure can be released via several valves (special valve) as well as via the outlet valves.Furthermore, the pressure in the wheel brake can be maintained by closing the valve while the pressure generator is operating at low pressure while the pressure in the wheel brake is high. This provides new degrees of freedom that are very advantageous in a centralized control strategy using the primary control unit.

[0037] In one embodiment, at least one of the wheel brakes, which is assigned to a special solenoid valve, also has an outlet valve. The corresponding outlet valve can be assigned to the wheel brake. In one embodiment, the outlet valve and the special solenoid valve are used simultaneously to reduce the pressure in the respective wheel brake as quickly and effectively as possible. In particular, the primary control unit can be configured to control the assigned special solenoid valve and outlet valve, at least in a selected braking mode, such that brake fluid is simultaneously discharged from the wheel brake via the assigned special solenoid valve and the assigned outlet valve.

[0038] In one embodiment, the driving dynamics system has at least one second pressure supply unit. This preferably comprises a piston-cylinder unit or a rotary pump - i.e., its own pressure generator. The second pressure supply unit can be connected to at least one inlet of the first pressure supply unit to provide brake fluid. In one embodiment, the pressure supply unit not only performs a function in which it serves as a pressure reservoir, but also a function in which it is used as a (controllable / regulatable) pressure sink or, alternatively, has at least one valve for pressure reduction (e.g., central outlet valve, cf. WO2020165259A1, outlet valves of an ABS / ESP unit). The pressure reduction can be time-controlled using valves, but can also be PWM-controlled if inlet valves of an ABS / ESP unit are used for pressure reduction.If, for example, a piston-cylinder unit is used, a very low pressure, for example, a pressure of 1 to 5 bar, can be generated within the piston by retracting the cylinder, with the existing pressure difference leading to a rapid pressure reduction in the wheel brakes. In a (preferred) embodiment, the pressure supply unit provides brake fluid for a first and a second brake circuit, with at least one isolating valve preferably being provided for isolating the first and / or second brake circuit. This isolating valve can, as explained in more detail below, be designed similarly or identically to the special solenoid valve already described.

[0039] A plurality of first pressure supply units may also be provided and connected to the second pressure supply unit.

[0040] In one embodiment, the first pressure supply unit is (directly) connected to exactly two wheel brakes. These two wheel brakes are preferably assigned to wheels located on a first axle. In one embodiment, in addition to the first pressure supply unit, at least one further pressure supply unit is provided, which is (directly) connected to at least two wheel brakes on a second axle. In other words, the further pressure supply unit supplies two wheel brakes assigned to wheels located on the second axle. According to the invention, a plurality of first pressure supply units can therefore be provided as different modules, each module being assigned to a specific axle or the wheel brakes on a specific axle.Depending on the vehicle, in addition to the first and second axles, additional axles with additional pressure supply units may be provided, with each pressure supply unit of an axle preferably being communicatively connected to the primary control unit for receiving steering commands and braking commands. According to the invention, a direct connection of one device to another device can be understood as providing a hydraulic connection, for example via lines, that is not interrupted by other devices, such as valves or pressure generators.

[0041] In one embodiment (hereinafter also referred to as valve connection variant I), the special solenoid valve is connected, as is customary in state-of-the-art ABS / ESP systems, with the valve's armature chamber connected to the wheel brake and the valve seat connected to the pressure supply unit, and is designed to be open when de-energized. Pressure can be built up via a pre-pressure control and a PWM control of one or more of the special solenoid valves. Pressure is released via a time control of the same valves. Due to the tightening-resistant design, there is no risk of the special solenoid valve closing during pressure release.

[0042] In another embodiment (valve connection variant II), the valve seat of at least one special solenoid valve is connected to the wheel brake. This arrangement enables the pressure to be reduced quietly in the respective assigned wheel brake. Due to this arrangement, the valve opening cross-section can be adjusted, in particular by PWM control or current regulation. This allows for throttled pressure reduction via the special solenoid valve. In this embodiment, the pressure buildup via the special solenoid valve can be achieved via a time control or volume metering, which can be carried out in the second pressure supply unit, e.g., by adjusting the angle of rotation of a rotary pump or adjusting the piston travel of a piston-cylinder unit.

[0043] Both connection types allow a wheel brake to be decoupled from the system by simply closing it by energizing the special solenoid valve. A low holding current can be applied to keep the special solenoid valve closed. This decoupler can be advantageous if a defect, such as a leak, has been detected in the respective wheel brake.

[0044] In one embodiment, the first supply unit may comprise a rotary pump connected to and configured to build up and release pressure in the wheel brakes. Thus, the rotary pump can act as a pressure sink and implement rapid pressure reduction.

[0045] Furthermore, the task is solved by a driving dynamics system that includes:

[0046] - a primary control unit for detecting and / or generating steering commands and braking commands;

[0047] - four hydraulically operated wheel brakes, each assigned to a wheel;

[0048] - at least one electric traction motor with a traction motor control unit, wherein the traction motor is arranged to drive at least one of the wheels of the vehicle, wherein the primary control unit is communicatively connected to a traction motor control unit to control the traction motor to implement the steering commands and braking commands;

[0049] - at least one first electro-hydraulic pressure supply unit with o at least one electric motor-pump unit o at least two connections for connecting the wheel brakes; o electrically actuated wheel brake pressure adjustment valves or brake pressure adjustment valves; and o a first secondary control unit;

[0050] - at least one second electro-hydraulic pressure supply unit, which is arranged to provide brake fluid at at least one inlet of the first pressure supply unit for a first brake circuit and a second brake circuit, wherein the second pressure supply unit is assigned at least one isolating valve in the form of a special solenoid valve for isolating the first and / or second brake circuit, wherein the special solenoid valve comprises an electromagnetic drive with a first excitation coil, via which a valve actuator or valve tappet of the special solenoid valve can be adjusted between an open valve position and a closed valve position.

[0051] Alternatively, the object is achieved by a system for a vehicle with wheels (R1-R4), in particular a driving dynamics system, in particular as described in a previous embodiment. The system may comprise:

[0052] - a primary control unit (M-ECU) for detecting and / or generating steering commands and braking commands;

[0053] - four hydraulically operated wheel brakes (RB1-RB4), each assigned to wheels (R1-R4);

[0054] - at least one electric traction motor (TM1, TM2) with a traction motor control unit (S-ECU-TMHA), wherein the traction motor (TM1, TM2) is arranged to drive at least one of the wheels (R1-R4) of the vehicle, wherein the primary control unit (M-ECU) is communicatively connected to a traction motor control unit in order to control the traction motor (TM1, TM2) to implement the steering commands and braking commands; - at least one first electro-hydraulic pressure supply unit (BMI) with o at least one electric motor-pump unit o at least two connections for connecting the wheel brakes (RB1-RB4); o electrically actuated wheel brake pressure adjustment valves orBrake pressure adjustment valves, and o a first secondary control unit (S-ECU1); at least one second electro-hydraulic pressure supply unit (BM2), which is arranged to provide brake fluid at at least one inlet of the first pressure supply unit for a first brake circuit (BK1) and a second brake circuit (BK2), wherein the second pressure supply unit (BM2) is assigned at least one isolating valve (TV1, TV2) in the form of a special solenoid valve (MV2k) for isolating the first and / or second brake circuit (BMI, BM2), wherein the special solenoid valve (MV2k) comprises an electromagnetic drive with a first excitation coil (SPla), via which a valve actuator (7) or valve tappet (7a) of the special solenoid valve (MV2k) can be adjusted between an open valve position and a closed valve position.

[0055] The system can be characterized in that the special solenoid valve (MV2k) is resistant to closing, in particular by the provision of an additional force device which comprises a permanent magnet (PM) and / or a second excitation coil (SPlb, SP2) and which is arranged to provide at least one retaining force (FPM, FEM2) acting on the valve actuator (7) or valve tappet (7a).

[0056] One aspect of the invention is that the special solenoid valve is resistant to closing, in particular by providing an additional force device which comprises a permanent magnet and / or a second excitation coil and which is arranged to provide at least one retaining force acting on the valve actuator or the valve tappet.

[0057] The special solenoid valve can therefore also be used as a separating valve, for example as part of the second pressure supply unit (hereinafter also referred to as the second brake module BM2), whereby the second brake module BM2 does not need to contain a separating valve if there is only one hydraulic connection to the first brake module (Figure 9, Figure 10, Figure 15) and is also referred to as the brake module BM2 in the embodiments without a separating valve. The pull-resistant properties also lead to a significant improvement in the system here. In general, other valves can also be used according to the invention which have corresponding pull-resistant properties. The system is preferably a 2-box system in which the first pressure supply unit is part of a first box and the second pressure supply unit is part of a second box.

[0058] If a special solenoid valve is used that has the aforementioned permanent magnet and / or the second excitation coil, it can be designed similarly or identically to that described above. The additional force device can generate an additional restoring force in addition to the aforementioned retaining force.

[0059] With the advantageous use of a second pressure supply unit for pressure reduction to a low friction coefficient, even cost-effective ABS / ESP brake systems can achieve a new level of control quality and can certainly compete with innovative 1-box brake systems (DE102013222281A1, Brake Manual 5th Edition, Chapter 20.3 "Integrated Brake System MK CI") in terms of braking distance performance.

[0060] Regardless of the design of the second pressure supply unit, in one embodiment, the first pressure supply unit can be equipped with a rotary pump with pressure build-up and pressure reduction according to the direction of rotation of the rotary pump, thereby creating a further degree of freedom in pressure reduction. Furthermore, in this embodiment, due to the lack of backpressure in the accumulator chamber, the pressure can be effectively reduced during ABS operation with low friction coefficients ("low-."). This results in a highly precise and cost-effective system.

[0061] In a (further) embodiment, the first pressure supply unit can be designed such that pressure reduction is provided into a reservoir instead of a storage chamber. This is possible due to the significant safety gain achieved by the special solenoid valve according to the invention, particularly when used as an inlet valve, and significantly improves ABS control performance.

[0062] In one embodiment, a braking torque is built up simultaneously on one or more axles together with electric traction motors via the electric traction motors and the pressure of the first and / or second pressure supply unit. In this context, during the pressure build-up, an electric brake force distribution (EBD) can be carried out by means of the first and / or second pressure supply unit in order to prevent the rear wheels from locking before the front wheels. If a wheel locking pressure is reached, the ABS control can be activated according to the invention and the braking torque of at least one traction motor is reduced very quickly. A corresponding procedure does not pose a safety risk for electric traction motors that are operated at high voltage (> 400 V, in particular > 700 V) and have braking torque gradients > 10,000 Nm / s and functions quickly enough for a safe braking torque reduction, possibly already in the first control cycle.According to the invention, this can be achieved by introducing the central vehicle dynamics control system (FDS), which synchronously controls the electric traction motors (TM) and the pressure generation units and very quickly detects an ABS event by evaluating wheel speed sensors. For this purpose, the primary control unit can be communicatively connected to the wheel speed sensors in such a way that the corresponding sensor values ​​can be read directly. The inventive approach enables a TTL of 150 ms to be achieved for the automatic emergency brake with only pressure generation via the pump of the first brake module (BMI). Such comparable values ​​were previously reserved only for single-box brake systems with powerful brushless motors.

[0063] Alternatively or additionally, according to the invention (in addition to the electric traction motors), a 6-piston pump or a more powerful brush motor can also be used in the first pressure supply unit, thus achieving a shorter TTL time. With this approach, good TTL times, possibly in the range of 150 ms, can be achieved even with less powerful electric traction motors. According to the invention, the individual measures of the embodiments can be combined in various ways in a modular concept.

[0064] The pressure supply unit can be designed for both pressure build-up and pressure reduction. The first and second pressure supply units can each have a secondary control unit, each with at least one communication interface. These communication interfaces can be used to establish communication with the primary control unit. In particular, measurement signals and control setpoints can be exchanged. The special solenoid valve of the second pressure supply unit can be arranged such that a valve seat of the special solenoid valve is (directly) connected to an inlet of the first pressure supply unit (valve connection variant III). Due to the arrangement of the special solenoid valve, the valve opening cross-section can be adjusted, in particular by PWM control or current regulation.This special arrangement also allows pressure to be throttled from the first pressure supply unit via the special solenoid valve, thus reducing it quietly. In this arrangement, pressure buildup is preferably achieved via a timer or volumetric metering (see the previous explanation on pressure control / pressure regulation via volumetric metering).

[0065] In one embodiment, the primary control unit is designed to implement a wheel brake-specific or brake circuit-specific pressure control by controlling at least one of the special solenoid valves of the first pressure supply unit and / or the at least one second pressure supply unit.

[0066] In one embodiment, the primary control unit is designed to detect a wheel circuit failure by measuring pressure when special solenoid valves of the first pressure supply or an inlet valve are closed. A corresponding diagnostic method can include measuring whether the pressure in the system drops even though all relevant valves are closed. If this is the case, it can be assumed that a leak is present. Closing a special solenoid valve can still cause pressure to build up in the remaining brake circuits or other non-leaking wheel circuits. For example, the second pressure supply unit can build up pressure with a piston movement. If there is no pressure increase that correlates with the piston movement, a leak can be concluded in this case too.

[0067] As already explained, the primary control unit can be configured to isolate a defective brake circuit by closing at least one of the isolation valves. In a preferred embodiment, it is thus possible to perform isolations either for individual wheel circuits or for individual brake circuits in order to isolate defective brake circuits or wheel brake circuits while maintaining the functionality of the rest of the system.

[0068] The primary control unit can be configured to implement (axle-by-axle) ABS by controlling at least one of the isolation valves and (alternating) pressure buildup and pressure reduction via the second pressure supply unit. Unlike conventional systems, the second pressure supply unit can also be used to implement at least a (rudimentary) single-channel ABS. This leads to additional redundancies.

[0069] In one embodiment, the primary control unit is configured to implement (automatic) emergency braking by controlling the traction motors and at least the first pressure supply unit in parallel. A corresponding control strategy can also be implemented with only one traction motor.

[0070] The primary control unit can be designed to provide an (automatic) emergency braking function (AEB) or a braking torque build-up, in particular a high braking torque (> 3 m / s 2 Vehicle deceleration) by controlling the electric traction motor and electro-hydraulic braking. When implementing emergency braking, the braking torques of the electric traction motors and the first pressure supply unit are combined up to a high deceleration (>5 m / s 2 ), preferably up to the maximum deceleration (>8 m / s 2 , especially > 9.5 m / s 2) is generated additively. An ABS situation can be detected by evaluating wheel speed sensors during the emergency braking function, i.e. during the highly dynamic pressure build-up. In this case, the primary control can reduce the braking torque of the electric traction motor and / or the electro-hydraulic brake (central) on one or more locking wheels or the braking torque of a vehicle axle. In one embodiment, the first electromagnetic drive is redundantly provided with at least a first solenoid valve driver and a second solenoid valve driver, wherein the secondary control unit for controlling the at least one special solenoid valve is communicatively connected to the first solenoid valve driver and the primary control unit for controlling the at least one special solenoid valve is communicatively connected to the second solenoid valve driver.This means that the special solenoid valve can be activated by two separate control units, ensuring continued operation even if one of the control units fails. The communication connection can be an electrical connection.

[0071] In one embodiment, the primary control unit is designed to at least temporarily adjust a brake pressure in at least a selection of the wheel brakes in a multiplex / PPC method, wherein the primary control unit sends a control signal to the second pressure supply unit in order to build up or reduce the pressure.

[0072] In one embodiment, a new FDS architecture is created with communicative interfaces Int-BM1, Int-BM2 between the central computer or primary control unit and the control unit of a brake module (BMI or BM2), and, in the case of multiple brake modules (BMI and BM2), a further interface Int-BM between the control units of the two brake modules S-ECU1 and S-ECU2. The Int-BM interface is based on the VDA360 guideline, which was defined for the interaction of an electric secondary brake booster (e.g., i-Booster product) and an ESP-hev braking system for regenerative braking, including an interface for valve actuation of the ESP-hev system's exhaust valves. In addition, at least one electric traction motor (TM1, TM2, TM3) is integrated into the FDS.At least one further interface is provided between the central computer and the traction motor, preferably an interface IntTMi between the M-ECU and the secondary control unit of the respective traction motor (S-ECU-TMi) or an interface between the M-ECU and the control unit of the respective axle of a vehicle (IntTM. HA, IntTMvA), especially when the axle comprises several traction motors. This configuration is advantageous when, for example, a traction motor is provided for each wheel on the rear axle in order to accelerate or brake the wheel individually. One or more of the communication interfaces can be an electrical connection, a wireless connection, or an optical connection, with two communication paths preferably being selected. A first communication path can be redundant, and a second communication path can be used to check the signals of the first communication path. In one embodiment, the 2 out of 3 principle is implemented with two different signal transmission types so that the requirements for SAE Level 5 are met and transmission errors can be ruled out.The 2 out of 3 principle must be strictly observed for braking systems for SAE Level 4 with e-pedal or SAE Level 5 without pedal, since there is no longer a brake pedal with access by the driver.

[0073] In addition, the primary control unit can also control the solenoid valve drivers of the inlet valves of the first pressure supply unit. This allows wheel-specific pressure control, in particular a 4-channel ABS or wheel-specific braking torque interventions for steering functions, to be implemented exclusively with the second pressure supply unit and the special solenoid valves on the wheel brakes, regardless of the operability of the pressure generator, e.g., the pump, and the secondary control unit of the first pressure supply unit. In one embodiment, the solenoid valve drivers, in particular the special solenoid valves, are designed redundantly.

[0074] In one embodiment, a solenoid valve electronics unit is provided on the secondary control unit of the first pressure supply unit, which is particularly galvanically isolated from the main control board. This unit is supplied with its own voltage and can thus be operated independently. This allows a fully functional ABS system to be implemented even in the event of a complete failure of the first pressure supply unit.

[0075] Furthermore, the implementation of a central vehicle dynamics control system in a domain of a central computer with chassis control by integrating steering actuator(s), e.g., an electric power steering system, and electric traction motor(s), can be simplified. Existing software architectures can essentially be retained, and comprehensive additional functions requiring interaction between the steering actuator(s) and electric traction motor can be easily implemented, e.g., in the primary control unit. In one embodiment, functions of the first pressure supply unit are transferred to the primary control unit, so that the first pressure supply unit is only designed as a pressure regulator.

[0076] The driving dynamics system FDS can, as the central driving dynamics control system for a vehicle, comprise several of the components listed below:

[0077] - a primary control unit (M-ECU) for detecting and / or generating steering commands and braking commands

[0078] - where in the primary control unit at least one of the functions ABS, ESP, ASR, ACC, AEB, regenerative braking, steering in redundant microcontroller jxCl, |iC2, |iC3.

[0079] - at least one electric traction motor TM1, TM2, TM3 for driving and braking wheels, one secondary control unit (ECU-TM1, ECU-TM2, ECU-TM3) or vehicle axle control unit (ECU-VA, ECU-HA) each

[0080] - at least 1 brake module (BMI) with hydraulic connections for several wheel brakes

[0081] - a central vehicle model by means of which the steering and braking commands can be calculated taking into account the friction coefficient of the road surface, the vehicle speed and / or the dynamic weight distribution during braking

[0082] - whereby for braking and steering at least the wheel speed sensors, preferably further sensors (acceleration sensors and / or weight sensors) are read into the primary control unit.

[0083] The driving dynamics system FDS can be distinguished by the fact that the primary control unit (M-ECU) uses steering and braking commands for the

[0084] Brake torque modulation (e.g. ABS, ESP, EBV) is sent to several secondary control units in such a way that either o an electric traction motor or a brake module BMI or BM2 provides a basic braking torque and the braking torque modulation (e.g. ABS, ESP) is controlled via electric traction motors o or the braking torque modulation is controlled jointly by at least one electric traction motor and at least one brake module (BMI or BM2) o or the braking torque modulation is controlled via electric traction motors on the rear axle and the braking torque modulation on the front axle is controlled via at least one electro-hydraulic brake module (BMI, BM2).

[0085] The FDS can be used to such an advantage that the brake units can be optimized depending on the braking situation (comfort braking, emergency braking), road surface conditions (braking on asphalt, snow, ice, jumps, gravel), and the availability of the brake modules with a view to maximizing recuperation and braking control performance in different driving situations. Furthermore, control via the FDS and regenerative braking via electric traction motor(s) should reduce the costs of the brake calipers, even at high deceleration rates of <5 m / s. Regenerative braking minimizes the thermal load on the friction brake and enables the downsizing of a disc brake on the front axle or the use of a drum brake on the rear axle.

[0086] During braking torque modulation, at least one braking module (BMI, BM2) and at least one electric traction motor (TM1, TM2, TM3) are controlled simultaneously via the central primary control unit and the braking torque commands are distributed between at least one braking module and at least one electric traction motor.

[0087] By designing the braking system with at least one brake module (BMI, BM2) and special solenoid valves, preferably with direct control via a primary control unit, wheel-specific braking torque interventions can be implemented via the primary control unit. According to the invention, in the event of a wheel circuit failure, the remaining wheel circuits can continue to operate by closing a special valve of the failed wheel brake circuit. Furthermore, the TTL time can be minimized through the central control of at least one traction motor and at least one brake module.

[0088] The following functions particularly benefit from this version:

[0089] • Automatic emergency braking AEB with high dynamics (50-180 ms) through joint braking torque interventions via electric traction motor and brake module

[0090] • Wheel-specific braking torque interventions for steering support (Brake to Steer BtS) or driving dynamics (Brake to Torque Vectoring BtTV) • Vehicle stabilization (ESP function) at high yaw speeds

[0091] • Wheel-specific or axle-specific regenerative braking.

[0092] According to the invention, the new functions and improved reliability can be achieved starting from a dual-circuit ABS / ESP braking system by modifying the hydraulic design and replacing a few components. This creates a three-circuit or four-circuit braking system with significant safety advantages. The FDS driving dynamics system can also provide wheel-specific braking torque control via a pressure interface (Int-BMl) with the primary control unit. Wheel-specific or axle-specific braking torque control via the pressure interface is easier to implement than with a standard ESP unit. The system according to the invention can also regulate the pressure in the individual wheel brakes more precisely and dynamically.By means of the system according to the invention, wheel-specific braking torque interventions can always be carried out on three wheel brakes, which leads to significant advantages in vehicle stabilization functions and highly dynamic processes, such as AEB with electronic brake force distribution (EBD).

[0093] Furthermore, the driving dynamics system meets the redundancy requirements of autonomous driving according to SAE Level 3-5 (redundant brake booster, redundant ABS and EBD function). The system can be operated with two pressure supply units (so-called 2-box braking system, each with one pressure supply unit) in such a way that, in addition to the redundant ABS / ESP function, the control performance at low friction coefficients is significantly improved compared to the state of the art through the interaction of the ESP-X unit with an external pressure generator DV2, particularly as part of a pressure supply unit. The advantageous integration into a domain architecture of an electric vehicle with a central computer in the form of the primary control unit is also intended to improve the emergency braking function AEB through synchronized setpoint specification of braking torques to the control unit(s) of one or more electric traction motors as well as setpoint specification of braking torques.This means the TTL can be significantly reduced.

[0094] Since the braking torque of the electric traction motors acts either only on one vehicle axle or with different braking torques on multiple vehicle axles, the brake force distribution (EBD) must also be controlled. This means that the hydraulic braking torque must be distributed between the front and rear axles differently than in a standard EBD control system. The system according to the invention can prevent the rear axle wheels from locking before the front axle wheels, and the front axle wheels may only lock at a deceleration of 0.85 g. In the event of wheel locking, the ABS intervenes, and the braking torque of the electric traction motor must be taken into account in the ABS control.

[0095] An embodiment of the driving dynamics system according to the invention can be characterized in that at least two, preferably four, inlet valves of the first pressure supply unit are replaced by special solenoid valves that are normally open. In contrast to the prior art, the special solenoid valve that is resistant to closing does not have a check valve arranged in a parallel hydraulic path to the inlet valve or integrated into the inlet valve. As already explained in the problem statement according to the prior art, the check valve serves to ensure a more reliable brake pressure reduction from the wheel brakes even in the event of a failure or partial failure of the braking system, e.g., the pressure supply unit. However, this can be dispensed with in the systems according to the invention.

[0096] The aforementioned task is further achieved by a switching valve. This switching valve can be used in particular in conjunction with the driving dynamics systems described above. This switching valve can function as an intake valve (of an ESP system) or as a separating valve for a second pressure supply unit.

[0097] The switching valve can include:

[0098] - a valve actuator or valve tappet;

[0099] - an armature connected to the valve actuator or valve tappet;

[0100] - an electromagnetic drive with at least one excitation coil for adjusting the valve tappet between an open valve position and a closed valve position along a longitudinal direction.

[0101] The switching valve can be characterized in that the armature comprises at least one permanent magnet. In one embodiment, this is arranged such that the valve actuator or valve tappet is held in the open valve position by the magnetic force generated by the permanent magnet. This magnetic force preferably also acts without energizing the electromagnetic drive. This allows the switching valve to be particularly resistant to closing, especially when high volume flows pass through the valve.

[0102] The switching valve described above, as well as the embodiments of the switching valve explained below, can be used as a special solenoid valve in the sense of the present invention.

[0103] In one embodiment, at least one permanent ring magnet or a plurality of permanent magnets is provided in the armature. The permanent ring magnet or the plurality of permanent magnets can have a pole orientation that is substantially perpendicular to the longitudinal direction.

[0104] In one embodiment, the ring permanent magnet or the plurality of permanent magnets are embedded axially and radially in a material with ferromagnetic conductive properties.

[0105] In one embodiment, the permanent magnets (PM) and / or the adjacent ferromagnetic flux guides are arranged and dimensioned such that, when the electromagnetic drive is de-energized, the magnetic force moves the valve tappet from the closed valve position to the open valve position. This is a de-energized valve that opens automatically in the event of a power failure. This has particular advantages, as already explained, particularly in conjunction with the described driving dynamics system.

[0106] The electromagnetic drive can comprise the first excitation coil and at least one second excitation coil. This provides redundant excitation coils, which are preferably connected to separate solenoid valve drivers. This generally increases the valve's reliability. Furthermore, the valve can be separately connected to different control units, e.g., one of the secondary control units and the primary control unit.

[0107] This allows one of the control units to take control of the valve if the other control unit fails.

[0108] In one embodiment, an H-bridge with four switches, in particular power semiconductors, is provided, by means of which an electromagnetic field with different polarization can be generated. This allows the valve to be actively closed and opened when the excitation coil is energized, depending on the wiring of the H-bridge and the resulting current direction through the excitation coil. Independent of the flow direction, the valve can be operated by means of current control with variable cross-sections both during pressure build-up and pressure reduction. The H-bridge enables the electric magnetic field to be reversed by at least one excitation coil and also allows the magnetic field strength to be adjusted. This allows the force on the armature (in the effective direction) and the amplitude to be controlled.

[0109] In an (alternative) embodiment, the switching valve advantageously provides a new and at the same time cost-effective design according to the invention with a first soft iron magnetic circuit EMI and a second magnetic circuit EM2 generated via a permanent magnet, wherein in one embodiment the forces of the two magnetic circuits EMI and EM2 act on the armature of a ball seat switching valve.

[0110] Some of the switching valves according to the invention can be manufactured cost-effectively by using most of the components of a standard solenoid valve (e.g. armature diameter and magnetic circuit with coils) and modifying only the end part (head part) of the valve.

[0111] The head section is equipped with a permanent magnet circuit, meaning the special solenoid valve combines a soft iron magnetic circuit (EMI) and a second magnetic circuit (EM2) generated by a simple permanent magnet in a single valve. This design has the great advantage that existing production facilities can be used for manufacturing. Inlet valves, preferably with unchanged diameters and the same interfaces to the hydraulic block (HCU), can be easily replaced with the special solenoid valves using the typical press-in assembly technique, i.e., the special solenoid valves can be easily installed in an unchanged hydraulic block. Furthermore, the ECU (=secondary control unit), which is plugged onto a hydraulic block and carries the excitation coils of the solenoid valves, requires little or no modification.In general, the previously described BMI brake module with special solenoid valves (ESP-X) can be used in a variety of different configurations (AE) as follows:

[0112] A) Configuration A: Brake module BMI (e.g. as ESP-X) hydraulically connected to a vacuum brake booster;

[0113] B) Configuration B: BMI brake module hydraulically connected to an electric follower brake booster, e.g. as described in DE112009004636B4;

[0114] C) Configuration C: BMI brake module hydraulically connected to electro-hydraulic brake booster with pedal feel simulator;

[0115] D) Configuration D: Brake module BMI hydraulically connected to a second brake module BM2 and controlled via a primary control unit and an electric brake pedal;

[0116] E) Configuration E: BMI brake module as a stand-alone pressure control unit, controlled via a primary control unit, e.g. as an axle module for the actuation of two wheel brakes, or central hydraulics for the actuation of four wheel brakes.

[0117] The use of the special valve with a pull-proof closure (wheel brake circuits with the option of being isolated by closing the special solenoid valve) enables all AE configurations:

[0118] • a diagnosis of the leakage by, for example, measuring the pressure increase or volume flow during pressure build-up by a pressure supply unit with the valve closed

[0119] • a diagnosis of the wheel brake circuit failure by measuring the pressure increase or volume flow with the valve open and comparing it with the typical, previously measured and stored pressure-volume characteristic curve of the wheel circuit

[0120] • Decision on continued operation of the wheel brake circuit even in the event of minor leakage

[0121] • Decision to isolate the brake circuit by permanently closing the valve connected to a failed wheel brake circuit and continuing operation with three wheel circuits. • Pressure reduction either via outlet valves or the special solenoid valve.

[0122] • Maintaining wheel brake pressures when brake pressures in other wheel brakes are low.

[0123] Furthermore, in the event of a failure of, for example, an excitation coil or a solenoid valve driver of a normally closed exhaust valve, the pressure can alternatively be reduced via an inlet valve, thus increasing the availability of the driving dynamics system FDS.

[0124] Since the special solenoid valve is particularly important for function and safety, it is advantageous if this valve, in addition to its pull-tight design, also has redundant coils and solenoid valve drivers. With normally closed outlet valves, this redundancy can be omitted for cost reasons, since if an outlet valve fails, the pressure can still be reduced via the special solenoid valve. This redundantly ensures pressure build-up. This can greatly reduce the probability of a wheel brake circuit failing, and the driving dynamics system can be operated with a high level of reliability using all wheel brake circuit channels. Redundancy is particularly important for wheel-individual braking torque control, especially with central driving dynamics control via a primary control unit, e.g. for the BtS and BtTV functions.

[0125] In one embodiment of the invention, the known pressure control methods can remain unchanged, and pressure buildup occurs via pre-pressure control and operation of the intake valves with variable valve opening cross-sections. The solenoid valves are operated as proportional valves by current control (simply referred to in technical circles as PWM operation of the intake valves).

[0126] In a (further) embodiment, the new degrees of freedom in the control strategy can be utilized in the pressure control system. This allows for functional improvements in ABS operation as well as new functions, such as wheel-specific brake torque intervention via the pressure interface with the central computer. The new functions of the central vehicle dynamics control system include, in particular, wheel-specific brake torque control for torque vectoring (BtTV), brake torque intervention for yaw rate control of the ESP function or steering function (BtS), and / or axle- or wheel-specific regenerative braking.

[0127] In one embodiment (valve connection variant I), the valve seat of the intake valves, in particular the special solenoid valve, is connected to the brake circuit(s), and the armature chamber is connected to the wheel brake. Pressure control method A (=standard pressure adjustment mode or EVPWM / AVAI pressure control method) is used here, namely the conventional pressure control method with PWM control of the intake valves during pressure buildup and time control of the exhaust valves during pressure reduction (Brake Manual Fig. 20.12.a).

[0128] Alternatively, due to the non-closing inlet valves, pressure control method B (multiplex / PPC method, hereinafter also referred to as "special pressure adjustment mode I") can also be used with connection variant I. As illustrated in the Brake Manual 5th Edition, Chapter 20.4 "Integrated Brake System IBS" - Fig. 20.13, the multiplex / PPC method has great advantages for ABS control on low road friction coefficients because the pressure reduction gradient through pressure reduction via a piston-cylinder unit is not limited by the counterpressure of an accumulator chamber and thus smaller wheel speed drops of the locking wheel can be achieved. The non-closing inlet valve, particularly in the form of the special solenoid valve, is used in a manner corresponding to the switching valve shown in the Brake Manual Fig. 20.12.b.A further pressure supply unit, for example the second pressure supply unit, advantageously serves as the pressure source and pressure sink. The second pressure supply unit can comprise a piston-cylinder unit or a rotary pump, wherein the piston of the piston-cylinder unit is advanced during pressure build-up and retracted during pressure reduction, or the rotary pump is activated during pressure build-up (p. aU f ) and pressure reduction (p a b) the direction of rotation of the pump motor is changed.

[0129] When controlling pressure according to pressure control method B and using a piston-cylinder unit, the PPC method ("Piston Pressure Control"), which is well known in specialist circles, can be used. This method allows the pressure to be built up and reduced in a highly dynamic manner by using the sensor signals current, piston position and pressure-volume characteristic. In addition, this approach can be used to precisely control the temporal pressure curve. During the pressure change, the inlet valve can be operated open and the pressure curve is preferably controlled exclusively by the volume control via the piston-cylinder unit (control via a controller cascade with piston travel, piston speed and current of the electric motor) or controlled (current-proportional pressure control). During pressure build-up, the inlet valve can be opened either time-controlled or sequentially using the multiplex / PPC method (pressure control method B: p aU f / Pab: Multiplex / PPC method) also throttled with PWM control (p aUf: EVPWM; Pab(l): EV At , Pab(2): AV At Pressure control method). This allows the inventive driving dynamics system to simultaneously set different brake pressures on different wheel brakes with high precision.

[0130] In one embodiment, switching between pressure control method A (standard pressure setting mode) and pressure control method B (special pressure setting mode I) is possible during operation. Switching between the pressure control methods is preferably carried out in such a way that pressure control method A is used for ABS pressure control on asphalt (high-p) or in the event of a friction coefficient jump (p-jump), whereby high pressure changes must be achieved at several wheel brakes simultaneously. Pressure control method B is preferably used for low friction values, e.g., snow / ice (low-p). The primary control unit is preferably designed to detect the different conditions. In one embodiment, one brake circuit of the driving dynamics system can be operated with pressure control method A and the second brake circuit with pressure control method B, provided the primary control unit is configured accordingly.

[0131] In another embodiment (valve connection variant II), the special solenoid valve is connected to the wheel brake via the valve seat, allowing the pressure to be reduced in a throttled manner with a variable valve opening cross-section. In this embodiment, pressure can be built up either simultaneously or sequentially using the second pressure supply unit, preferably by displacing the piston and using time control instead of PWM operation according to a multiplex / PPC method. In this embodiment, the control / regulation strategy of the first pressure supply unit or the primary control unit is preferably adapted so that during pressure reduction, the second pressure supply unit is used as a controllable or adjustable pressure sink and pressure source. The differential pressure to the wheel brake pressure can be detected by determining the piston position and adjusted accordingly.With this valve connection variant II, one or more exhaust valves can be dispensed with. For example, four special solenoid valves can be used as normally open intake valves and two normally closed exhaust valves on the front axle. Exhaust valves on the rear axle are then unnecessary. Such a system offers high dynamic performance and low noise.

[0132] In the valve connection variant II, a third pressure control method C (p aU f: EV AT , Pab (1): EVPWM, Pab (2): AV ATPressure control method) can be used, in which pressure reduction occurs via variable valve cross-section control of the intake valves. Compared to valve connection variant I, the pressure can be reduced quietly via several intake valves simultaneously. This is particularly advantageous for low-noise control operation in electric vehicles. In one embodiment, pressure buildup occurs via pressure control method B (multiplex / PPC pressure control) or pressure control method C.

[0133] This results in designs with different pressure control methods, which are summarized again in the following table.

[0134]

[0135] According to the invention, it is possible to implement pressure build-up (pauf) and pressure reduction (pab) without redundancies. For example, pressure build-up can be implemented exclusively via intake valves (EV) (see table row with "pauf(EV)" in the first column) and pressure reduction exclusively via exhaust valves AV (see table row with "pab(AV)" in the first column).

[0136] However, redundancies are preferred, as shown in the table, whereby a redundant solenoid coil and a redundant driver for the inlet valve are preferably provided as redundancy for the pressure build-up (see table row with “p aU f (EV), red. solenoid / driver" in the first column).

[0137] In some embodiments, redundancy for pressure reduction can be ensured by performing pressure reduction via outlet valves (see table row with "Pab(AV)" in the first column) or inlet valves (see table row with "p ab(EV)" in the first column). Without these hardware and software redundancies, for example, if a solenoid coil of an exhaust valve fails, pressure reduction cannot occur via the exhaust valve because the valve is closed without current and thus blocks pressure reduction. This can lead to a permanent blockage of the associated wheel brake.

[0138] The driving dynamics system according to the invention generally has the advantage that wheel-individual braking torque interventions and novel control strategies for regenerative braking can be provided more easily and efficiently because, in contrast to the prior art, the special solenoid valve can at least in some embodiments maintain the pressure in a selected wheel brake while varying the braking pressure in other wheel brakes.

[0139] When pressure is reduced via the special solenoid valve, in contrast to conventional methods with pressure reduction via outlet valves, the pump of the first pressure supply unit must be activated to return the pressure. This applies particularly to embodiments according to the configurations (C) and (D) described above. However, in ABS operation with a low friction coefficient ("low-."), the method is also entirely possible with configuration (B). Corresponding advantages also arise with configuration (E) if a controllable or adjustable pressure sink, e.g., in the form of a rotary pump, is provided in one embodiment of the first pressure supply unit, which can reduce pressure by reversing its direction of rotation.

[0140] The object mentioned above is further achieved by a method. In particular, the object is achieved by a method for adjusting a brake pressure in at least one wheel brake of a braking system, which comprises the following steps:

[0141] - Determining that pressure is to be released from at least one of the wheel brakes, namely a target wheel brake;

[0142] - selecting a pressure reduction mode from a first pressure reduction mode and a second pressure reduction mode;

[0143] - if the first pressure reduction mode is selected, opening at least one of the outlet valves associated with the target wheel brake to implement the pressure reduction;

[0144] - when the second pressure reduction mode is selected, keeping the outlet valve associated with the target wheel brake closed and opening at least one of the inlet valves associated with the target wheel brake and generating a differential pressure in an (external), preferably second, pressure supply unit in order to implement the pressure reduction from the target wheel brake via the inlet valve.

[0145] One aspect of the invention is that, for optimal pressure reduction, especially depending on the situation, different modes can be selected. In at least one mode, the pressure reduction takes place via a (special) inlet valve. This enables, on the one hand, an improvement in availability (e.g., operation in the event of partial valve failure) and, on the other hand, a pressure reduction with lower pressure oscillations and thus less noise, namely

[0146] • the pressure can be released even if an outlet valve fails (the outlet valve is closed without power in case of failure),

[0147] • the pressure reduction can be regulated or controlled via an external pressure source in the pressure gradient and / or pressure gradient curve,

[0148] • If valve connection variant II is selected, the pressure can be reduced quietly using the special valves.

[0149] Within the scope of the invention, keeping a valve, in particular an exhaust valve, closed does not necessarily require that this valve be actuated in any way. Rather, a normally closed valve, such as is frequently used as an exhaust valve, can be kept closed according to the invention by not applying any current and not issuing any kind of activation signal.

[0150] Alternatively, the object is achieved by a method for carrying out ABS braking in a vehicle, the method comprising:

[0151] - Determining a required pressure reduction gradient for at least one wheel brake;

[0152] - Using the required pressure reduction gradient to select a pressure setting mode from a plurality of pressure setting modes, the pressure setting modes comprising at least a first and a second pressure setting mode;

[0153] - when the first pressure adjustment mode is selected, releasing the pressure from at least one wheel brake via at least one exhaust valve using a timing control;

[0154] - if the second pressure adjustment mode is selected, reducing the pressure from a wheel brake, preferably with the outlet valve closed, exclusively via a further solenoid valve, whereby the pressure from the wheel brake is transferred via the further valve into a controllable / regulatable pressure sink.

[0155] The mode used for pressure reduction is therefore selected depending on the required pressure gradient. Additionally or alternatively, the amount of fluid to be removed or the pressure difference can also be taken into account in the selection.

[0156] The first pressure setting mode can be a standard pressure setting mode, as previously explained. The second pressure setting mode can be the special pressure setting mode I.

[0157] In one embodiment, the plurality of pressure adjustment modes includes a third pressure adjustment mode, e.g., special pressure adjustment mode II. When the third pressure adjustment mode is selected, the pressure from at least one wheel brake can be reduced, at least temporarily, in parallel via at least one outlet valve assigned to the wheel brake and at least one further solenoid valve assigned to the wheel brake. The further solenoid valve can be a special solenoid valve, as described in connection with the various embodiments. By at least temporarily simultaneously using an inlet valve and an outlet valve for pressure reduction, the pressure can be reduced quickly and efficiently.

[0158] In one embodiment, a low pressure is set in the pressure sink, in particular < 5 bar, preferably < 3 bar, when the second pressure setting mode is selected.

[0159] The object mentioned above is also achieved by a primary control unit with instructions for implementing at least one of the described methods. Furthermore, the object is achieved by a vehicle or driving dynamics system with one of the described primary control units, in particular the primary control units described last.

[0160] Further advantageous embodiments emerge from the subclaims.

[0161] The invention is described below using several exemplary embodiments, which are explained in more detail with reference to the figures. Herein:

[0162] Figure 1: an ESP hydraulic circuit diagram according to the state of the art;

[0163] Figure 2a: an FDS system architecture with primary control unit and several secondary control units for traction motors and two brake modules BMI, BM2

[0164] Figure 2b: an exemplary embodiment of the brake modules according to Figure 2a with special solenoid valves as isolating valves;

[0165] Figure 2c: a valve connection variant for connecting the special solenoid valves as isolating valves according to Figure 2b in the second brake module;

[0166] Figure 3a: a schematic representation of a first brake module BMI, in which two inlet valves of a brake circuit are equipped with special pull-proof solenoid valves (with 3-channel brake torque modulation function);

[0167] Figure 3b: a schematic representation of a first brake module with a connected second brake module, wherein in the first brake module the four inlet valves of the two brake circuits are equipped with special pull-proof solenoid valves (with 4-channel brake torque modulation function);

[0168] Figure 4a: a schematic representation of a special solenoid valve with a permanent magnet and return spring; Figure 4b: a displacement-force diagram illustrating the forces acting on the valve actuator of the special solenoid valve according to Figure 4a;

[0169] Figure 5a: a schematic representation of a special solenoid valve with a permanent magnet integrated in the valve armature, whereby the armature can be actuated by an electromagnetic field with different polarization;

[0170] Figure 5b: a displacement-force diagram to illustrate the forces acting on the valve actuator of the special solenoid valve according to Figure 4a as a function of the applied current;

[0171] Figure 6: an H-bridge as a driver for the special solenoid valve according to Figure 5a for the generation of an electromagnetic field with different polarization;

[0172] Figure 7a: a schematic representation of a modification of the embodiment according to Figure 3b without UPS valves (with 4-channel braking torque modulation function);

[0173] Figure 7b: a schematic representation of a modification of the embodiment according to Figure 3b without USV valves and with check valves as a replacement for the HSV valves (with 4-channel braking torque modulation function);

[0174] Figure 8a: a schematic representation of a first brake module for two wheel brakes with a single-piston pump, in which the two inlet valves are designed as special solenoid valves (pressure reduction into a storage chamber);

[0175] Figure 8b: a schematic representation of a modification of the embodiment according to Figure 8a with a multi-piston pump (pressure reduction into a storage tank);

[0176] Figure 8c: a schematic representation of a modification of the embodiment according to Figure 8a with a rotary pump instead of the piston pump (pressure reduction via outlet valves into the storage tank and / or special solenoid valves with a controlled / regulated rotary pump as a pressure sink);

[0177] Figure 9: a schematic representation of a modification of the embodiment according to Figure 7b with only one hydraulic connection for the second brake module;

[0178] Figure 10: a schematic representation of a modification of the embodiment according to Figure 9 without storage chambers;

[0179] Figure 11: a schematic diagram for visualizing a control strategy of an intake valve;

[0180] Figure 12: a schematic diagram for visualizing a control strategy of an exhaust valve;

[0181] Figure 13a: a schematic representation of the use of the first brake module from Figure 3a in conjunction with an electrically driven piston-cylinder unit as a second brake module, wherein a pressure reduction from two wheel brakes is visualized;

[0182] Figure 13b: a schematic representation of the embodiment according to Figure 13a, wherein a pressure reduction in two wheel brakes is visualized;

[0183] Figure 14: a schematic representation of the use of the first brake module from Figure 3b in conjunction with an electrically driven piston-cylinder unit as a second brake module, wherein a pressure reduction is visualized;

[0184] Figure 15: a schematic representation of the use of the first brake module from Figure 3b in conjunction with a centrifugal pump as a second brake module, with a pressure reduction being visualized.

[0185] Character description

[0186] Figure 1 shows the hydraulic circuit diagram of a first brake module (BMI), designed as a standard ESP unit. The first brake module (BMI) assumes the function of the first pressure supply unit. It includes:

[0187] - four time-controlled exhaust valves AV1-AV4, each assigned to a wheel brake RB1-RB4;

[0188] - four PWM-controlled inlet valves EV1-EV4, each assigned to a wheel brake RB1-RB4;

[0189] - four check valves, each arranged parallel to one of the inlet valves EV1-EV4 and thus each assigned to a wheel brake RB1-RB4. The check valves are arranged in such a way that they close when pressure builds up in the wheel brakes RB1-RB4 and open when pressure decreases depending on the pressure conditions. Furthermore, there are the valves HSV1, HSV2, which allow brake fluid to be pumped via the pumps P, which are driven by the motor M, when valves USV1, USV2 are closed, thus building up pressure. Ultimately, the pumps P and the motor M form a two-piston pump (first pressure generator DV1), each with one piston for a first brake circuit BK1 and a second brake circuit BK2.

[0190] Storage chambers Spk allow brake fluid to be collected via the outlet valves AV1-AV4 during pressure reduction. The arrows illustrate the possible flow directions of the brake fluid during pressure buildup and pressure reduction.

[0191] The first brake module BMI, shown in Figure 1, provides an ESP and an ABS function. This ESP function is well known and described in the literature; it requires twelve solenoid valves. For the ABS function, only the inlet valves EV1-EV4 and outlet valves AV1-AV4, i.e., eight solenoid valves, are required. The first brake module BMI has two brake circuits BK1 and BK2, which are connected to a second pressure supply unit via two connection points. This can be one of the following:

[0192] I. Vacuum brake booster according to the state of the art

[0193] II. electric brake booster and brake pedal

[0194] III. Brake booster with pedal feel simulator and brake pedal

[0195] IV. Second pressure generator DV2 with valves. The first pressure supply unit in Figure 1a has a pressure sensor p / u, which is arranged to measure the pressure in a brake circuit BK1.

[0196] The following table shows the different functions of modern driving dynamics systems.

[0197]

[0198] Figure 2a shows the architecture of a vehicle dynamics system (FDS) according to the invention. The vehicle dynamics system has a first and a second traction motor TM1, TM2 on a rear axle (HA) of the vehicle and a third traction motor TM3 on a front axle (VA). The system can have a brake module (BMI) and optionally additional brake modules, for example, a second electrohydraulic brake module (BM2). A key element of the vehicle dynamics system is the primary control unit (M-ECU-Chassis Domain), or M-ECU for short, which controls the braking torques of the traction motors (TM1, TM2, TM3) and the brake modules (BMI, BM2) for at least one of the following functions:

[0199] A) Emergency brake AEB with simultaneous electronic brake force distribution (EBD)

[0200] B) Axle-individual or wheel-individual regenerative braking C) Braking via electric motor in case of failure of a brake module

[0201] D) Wheel-specific braking torque interventions for steering support or vehicle stabilization

[0202] The primary control unit (M-ECU) sends setpoints to the various components, including, in particular, target braking torques or target braking pressures. For certain functions, setpoint signals for pressure control or pressure regulation can be specified, e.g., control signals for solenoid valves and / or pre-pressures for the second brake module (BM2) with a second pressure generator (DV2) for pressure build-up or pressure reduction.

[0203] In one embodiment, the primary control unit (M-ECU) interfaces with the M-ECUAD control unit or the autonomous driving domain and evaluates additional information useful for effective and predictive control. This includes, for example, camera information about the road surface (snow, ice, rain) or information about the environment (distances to pedestrians and / or other vehicles).

[0204] Figure 2b shows a so-called 2-box brake system, comprising a first and a second brake module BMI, BM2. The first brake module BMI is similar in design to the first brake module in Figure 1a and has the functionality outlined above. The second brake module BM2 has a piston-cylinder unit (also called a plunger) driven by a spindle drive. The piston-cylinder unit forms a second pressure generator DV2. As part of the second brake module BM2, two isolation valves TV1, TV2 are provided, which can separate the brake circuits BK1, BK2 from the second pressure generator DV2 and enable the implementation of core functions:

[0205] - Brake booster;

[0206] - automatic emergency braking AEB;

[0207] - electronic brake force distribution EBV;

[0208] - 2-channel ABS function using the multiplex / PPC method. In one embodiment of the invention, redundancy functions can be provided to meet the requirements for Level 4 and Level 5 autonomous driving.

[0209] Both brake modules BMI and BM2 contain control units, hereinafter referred to as secondary control units S-ECU1, S-ECU2a, and S-ECU2b, which communicate with each other and preferably have interface functions (e.g., according to the VDA360 interface definition). Due to the communication options between the brake modules BMI and BM2 and the (higher-level) control function of the primary control unit M-ECU, the components can interact to implement specific functions, e.g., blending, in which the pressure generator of the second brake module builds up and reduces pressure while simultaneously actuating valves in the first brake module, e.g., the wheel inlet valves EV1-EV4 and wheel outlet valves AV1-AV4.

[0210] The connection of the BMI and BM2 brake modules to the M-ECU primary control unit via an IntBM1 and IntBM2 interface, respectively, enables the implementation of additional functions, such as ABS, ESP, AEB, ACC, and new domain functions such as torque vectoring (BtTV), steering interventions through braking (BtS), and recuperation management for the electric traction motors TM1, TM2, and TM3. In this context, the BMI and BM2 brake modules can act as slaves, i.e., pure pressure controllers, implementing specified setpoints, e.g., pressure or braking torque setpoints.

[0211] In at least one operating mode, the interface (primary) is used for the synchronized actuation of both brake modules BMI, BM2 by the primary control unit M-ECU, e.g. the piston of the second pressure generator DV2 of the second brake module BM2 is moved, while simultaneously one or more solenoid valves of the first brake module BMI are switched. Equipping the brake modules with a separate interface each allows the brake modules BMI, BM2 to be exchanged at any time, i.e. the brake modules BMI, BM2 can be obtained from different suppliers. Alternatively, only one interface IntBM1 or IntBM2 can be provided, which is communicatively connected to the primary control unit M-ECU. In this case, communication with the other unit takes place via a standardized interface Int2BM.In the exemplary embodiment, wheel speed sensors vRl, vR2, vR3, vR4 are read redundantly by at least two control units, for example one of the secondary control units S-ECU1, S-ECU2a, S-ECU2b and the primary control unit M-ECU, so that the wheel speed signals can always be transmitted via the interfaces IntBMl, IntBM2, Int2BM.

[0212] In the exemplary embodiment shown, the second brake module BM2 is hydraulically connected to a reservoir VB via a check valve RVNF (alternatively, a solenoid valve can be used instead of the check valve RVNF) and preferably has two three-phase connections (2x3) to meet the requirements for autonomous driving of levels 4 and 5, with three phases each being controlled by a secondary control unit S-ECU2a, S-ECU2b, with current sensors i / u and motor angle sensors a / u being provided, which are preferably also designed redundantly and are used for high-precision PPC pressure control or pressure regulation via piston position or current.The redundant design of some components of the second brake module BM2 can increase availability and, analogous to the design of steer-by-wire (two steering actuators, whereby one steering actuator is equipped with 2 x 3-phase motor connections and partially redundant electronics), a third fallback level can be created for SAE Level 5. For example, in the event of a pump motor failure and a partial motor failure (motor winding, power output stage on the ECU2a or ECU2b of the second brake module BM2), braking torque generation and braking torque control with approximately 50% of the motor torque is still possible. A pressure sensor p / u is preferably provided at the pressure supply output of the second brake module BM2, which is primarily used for calibration purposes. However, pressure control can also be carried out without this pressure sensor if the relationship between the BM2 braking torque and the current or piston position is established in another way.This also enables further redundancy.

[0213] In the embodiment shown in Figure 2a, two special solenoid valves MV2k are used in the second brake module BM2 as (circuit) isolating valves TV1, TV2. The special solenoid valves MV2k are particularly resistant to closing and designed so that they can be used to build up and relieve pressure with high flow rates Q. They are preferably suitable for implementing the pressure change for ABS operation in a highly dynamic manner using the Multiplex7PPC method (i.e., with pressure gradients > 1000 bar / sec, preferably > 2000 bar / sec). According to the invention, the special solenoid valves are designed to be resistant to closing in accordance with the system specification, i.e., to maximum brake pressures and maximum flow rates.

[0214] In one embodiment, special solenoid valves MV2k with a first soft iron magnetic circuit EMI and a second magnetic circuit EM2 according to Figure 4 or special solenoid valves MV2k with a magnetic circuit EMI and a permanent magnet PM in the armature of the valve according to Figure 5a are used. When using a special solenoid valve MV2k with a permanent magnet PM embedded in the armature, an H-bridge is preferably used for current control, as explained in more detail with reference to Figure 6. The special solenoid valve MV2k can then be operated with current control and a variable valve cross-section both during pressure build-up and pressure reduction. This enables particularly quiet and highly precise pressure control during pressure build-up and pressure reduction. In the latter embodiment, a magnetic force of varying magnitudes in both directions of movement can be generated using a magnetic circuit EMI and an excitation coil SP1.Due to the advantageous positioning of the permanent magnet PM, a restoring force is generated even in the de-energized state, so that a return spring RF can be dispensed with. However, according to the invention, at least one return spring RF can also be provided in addition to the permanent magnet PM, as shown, for example, in Figure 4.

[0215] As an alternative to the valves shown in Figures 4 and 6, standard valves with an EMI magnetic circuit without a permanent magnet can also be used as special solenoid valves (cf. the state of the art for single-box brake systems (DE102013222281A1), Figure 1, reference numerals 26a and 26b). According to the invention, these valves are designed according to the pressure differences and pressure change rates of the implemented functions, in particular the AEB function and ABS function. Depending on the function, a stronger magnetic circuit with a larger armature and / or stronger return springs can be used.

[0216] The first brake module BMI functions autonomously with standard pressure adjustment mode (pressure control method A), whereas the brake module BM2 is operated with pressure control method B. Furthermore, according to the invention, it is possible to switch between a standard pressure adjustment mode and a special pressure adjustment mode I with pressure reduction via a special solenoid valve and use of the brake module BM2 as a pressure sink with a pressure <5 bar, in particular <3 bar, when ABS operation occurs at very low road friction values ​​(low-p, p-split).

[0217] This switching option also exists in the other embodiments (see Figures 3a, 3b, 7a and 7b) of brake systems with two brake modules in the version with storage chamber and the brake module and will not be explained separately again below.

[0218] Figure 2c shows the advantageous connection of the valve seat VS (e.g. in Fig. 5a) and the armature chamber of the isolation valves TV1, TV2 to the brake circuits BK1, BK2. The armature chamber AR (e.g. in Fig. 5a) is hydraulically connected to the pressure generator DV2 of the second brake module BM2, and the valve seat of the special solenoid valves MV2k is connected to the brake circuits. This arrangement allows a valve opening cross-section to be adjusted during pressure reduction, in particular by PWM control or current control, thus achieving low-noise pressure reduction. In this arrangement, pressure is then built up via controlled or regulated volume metering using the second brake module BM2, with the isolation valves TV1, TV2 preferably being time-controlled during pressure build-up, and the pressure build-up taking place using the multiplex / PPC process.

[0219] When using a special MV2k solenoid valve as shown in Figure 5a, the special current control via an H-bridge (see Figure 6) also allows pressure buildup with a variable valve cross-section, thus avoiding dead times in the multiplex / PPC process and allowing simultaneous pressure buildup without placing high demands on the drive. In this embodiment, the connection direction is irrelevant, since the special MV2k solenoid valve as shown in Figure 5a can be throttled in both directions. Additionally, it can be operated with appropriate current supply so that it is resistant to closing.

[0220] Figure 3a (abbreviation ESP-X3k.i2Mv. 4 RB. SK.KP) shows an embodiment of the first brake module BMI according to the invention, designed as a three-channel brake system with twelve solenoid valves, four wheel brakes RB1-RB4, accumulator chambers Spk, and a piston pump. This differs from a standard ESP system in that two inlet valves EVI, EV2 in the first brake circuit BK1 are designed as special solenoid valves MV2k. A parallel connection of check valves (cf. RV in Figure 1) can be omitted due to the special closing-resistant properties of these valves.

[0221] In one embodiment, the special solenoid valves MV2k are equipped with redundant solenoid coils MSI, MS2 and redundant solenoid valve drivers, enabling redundant operation or allowing a solenoid valve driver to be controlled via the primary control unit M-ECU. In the illustrated embodiment, the first brake circuit BK1 corresponds to the front axle brake circuit of a vehicle with a two-way brake force distribution. This means that the wheel brakes RBI, RB2 are the wheel brakes of the front axle VA of a vehicle.

[0222] In an alternative embodiment, an X-brake circuit distribution can be selected. In a minimal configuration, in this embodiment, the inlet valves EVI, EV2 assigned to the wheel brakes RBI, RB2 of the front axle VA can be designed as special solenoid valves MK2k. This modification of a standard braking system can achieve significant improvements, as a 2-circuit braking system becomes a 3-circuit braking system, with redundancy in pressure build-up and pressure reduction for two wheel brakes (see wheel brakes RBI, RB2 in Figure 3a). In contrast to the prior art, if one of the first or second wheel brakes RBI, RB2, e.g. wheel brake RB1, fails, the respective wheel brake circuit can be isolated by closing the inlet valve EVI assigned to the defective wheel brake RB1. This allows normal operation to continue with the three remaining wheel brake circuits, comprising wheel brakes RB2-RB4.In addition, in the event of a solenoid failure of one of the exhaust valves AVI, AV2, pressure can be redundantly reduced via the corresponding intake valve EVI, EV2. This requires that the respective driving dynamics system has a controllable pressure sink, e.g., by providing a corresponding second brake module BM2. With this inventive approach, significant improvements in achievable deceleration can be achieved compared to the prior art, since in the event of a failure, either (a) one wheel brake RBI, RB2 on the front axle VA and two wheel brakes RB3, RB4 on the rear axle HA or (b) two wheel brakes RB1, RB2 on the front axle VA are available for braking.

[0223] The above-described interface between the brake modules according to VDA360 is expanded in one exemplary embodiment such that, in addition to the interfaces described in DE102012211278A1, the inlet valves EVI to EV4 can also be actuated externally. Thus, if one wheel circuit fails, yaw rate control (ESP), torque vectoring via wheel-specific brake torque interventions (BtTV), and selective brake torque intervention for steering (BtS) are possible with the three remaining brake circuits. This inventive approach also has the advantage that all functions according to the table above can be retained without major software changes, particularly in the first brake module BMI. The software components responsible for pressure buildup must be modified such that the additional function of 3-circuit control is available if one wheel circuit fails.Furthermore, a control strategy that allows the primary control unit M-ECU to set a pressure can be implemented with little development effort, since pressure can be maintained at two wheel brakes RB1-RB4 by the special solenoid valve. This allows pressure to be built up and released for each wheel individually using the specially equipped inlet valves EV1-EV4 and the second brake module BM2. With wheel-individual brake torque control or brake torque regulation, there is no need to reduce pressure via the outlet valves AV1-AV4 (implementation of all isolation valves TV1-TV4 with special solenoid valves as shown in Figure 3b) or the outlet valves AVI, AV2 (implementation as shown in Figure 3a), and the complex recirculation of brake fluid using pump P can be dispensed with.If the need for reclaim is eliminated, the complex pressure oscillation compensation by the second brake module BM2 during reclaim by the first brake module BMI can be dispensed with, which has a beneficial effect on noise and wear.

[0224] A blending strategy for 2-box brake systems is described in WO2018234387A1 (pages 23-25) and can also be used for wheel-specific brake torque control or brake torque regulation during torque vectoring or steering interventions. Blending strategies or wheel-specific brake torque interventions can be implemented much more easily with the special MV2k solenoid valves. Furthermore, degrees of freedom arise because the pressure in one wheel brake RB1-RB4 can be maintained if the pressure supply unit of the second brake module BM2 sets a different pre-pressure for another wheel brake.

[0225] In one embodiment, the first brake module BMI can be expanded by two check valves RV1, RV2, which are part of a connection between the pumps P of the brake circuits BK1, BK2 and the reservoir VB (see dashed connection in Figure 3a). Compared to the prior art, this enables rapid suction through the pump, significantly faster than the suction process via the valves HSV1, HSV2 and other hydraulic resistances due to the combination with a second brake module BM2.

[0226] Figure 3b (abbreviation ESP-X4k, I2MV, 4 RB, SK, KP) shows the first brake module BMI according to the invention as a 4-channel brake system with twelve solenoid valves, four wheel brakes RB1-RB4, storage chambers Spk, and piston pump KP. This differs from a standard ESP in that in both brake circuits BK1, BK2, all inlet valves EV1-EV4 and their check valves RV1-RV4 (cf. Figure 1a) are each replaced by a special solenoid valve MV2k. In this exemplary embodiment, a 4-circuit brake system is created. The exemplary embodiment creates further degrees of freedom for wheel-individual brake torque control and provides a simple pressure interface to the primary control unit M-ECU. By creating a 4-circuit brake system in the first brake module BMI, a brake circuit division in the second brake module BM2 can be dispensed with.

[0227] For example, the second brake module can comprise a simple master brake cylinder (HZ) with only one piston (so-called single master brake cylinder SHZ) and one pressure chamber, as described in WO2020165294A2, wherein the master brake cylinder is preferably designed with redundant seals, wherein the SHZ only needs to be connected to one brake circuit, e.g. the front axle brake circuit. If a wheel circuit in the first brake module fails and the pumps P also fail, all that needs to be ensured is that the defective wheel brake circuit is disconnected. According to the invention, this can be done via the respective inlet valves EV1-EV4, which can be controlled internally and externally. For this purpose, the special solenoid valves MV2k are equipped with redundant coils and solenoid valve drivers.

[0228] Figure 4a shows a first advantageous embodiment of a pull-tight and bidirectionally effective normally open solenoid valve MV2k. According to the invention, the term "bidirectional" can be understood to mean that pressure build-up and pressure reduction occur via the MV2k valve. The special solenoid valve MV2k functions reliably in both flow directions Q, especially with large flow rates, such as 100 cm 3 / s - 120 cm 3 / s, and large pressure differences between the connections, e.g. 160 bar - 220 bar.

[0229] The special solenoid valve MV2k has the typical design of a solenoid valve with an electromagnetic circuit (EMI), armature 6, and valve actuator 7, comprising a valve tappet 7a that closes a valve seat VS. Furthermore, a return spring RF is provided, which has a linear force characteristic and acts on the valve actuator 7. The return spring biases the special solenoid valve MV2k into an initial position (position shown in Figure 4a).

[0230] Particularly for the aforementioned range of large pressure changes and flow rates, the special MV2k solenoid valve is designed to prevent itself from closing due to fluid dynamic forces. These are critical when there is high pressure at the armature chamber AR and low pressure at the hydraulic connection acting on the valve seat VS. Hydrodynamic flow creates a force Fhyd that exerts such a force on the valve stem that it is moved toward the valve seat VS. The return spring RF counteracts the fluid dynamic forces, but in extreme cases is not sufficient to actively prevent the valve from closing under the influence of fluid dynamic forces.

[0231] The magnetic circuit EMI generates (see Figure 4b) a current- and position-dependent magnetic force FEM I = f(isp) over the stroke s, which moves the armature towards the stop and the valve tappet 7a towards the valve seat VS. The magnetic force is non-linear and increases progressively with an increasingly small air gap S (Figure 4a), in particular with a polynomial formula with FMEMi = (s ma xs) n, n = 1.4-2 with increasing stroke s or smaller air gap S between armature 6 and stop (smax-s). With higher current isp the magnetic force can be increased but is limited by the saturation of the magnetic circuit. However the magnetic force can only act in the direction of the valve seat VS and therefore cannot generate a counterforce to a hydrodynamic force Fhyd if the flow Q originates from the armature chamber. If the valve is closed, the valve can remain closed when energized against a pressure acting on the valve seat. If the flow originates from the valve seat VS a counterforce can be generated, thus operation with a variable opening cross section is also possible, i.e. the special solenoid valve MV2k is operated with a variable valve opening cross section similar to a proportional valve. In technical terms this type of control is also referred to simply as PWM control.To make the special solenoid valve MV2k resistant to closing, a first variant uses a permanent magnet PM as a passive auxiliary force device to amplify the restoring force FRF, which is caused by the return spring RF. A permanent magnetic circuit comprises the permanent magnet PM and a pole plate 10. The permanent magnet is integrated into an auxiliary armature 6a, which is non-positively connected to the armature 6. The poles are aligned parallel to the longitudinal direction of the special solenoid valve MV2k, so that the magnetic force FPM of the permanent magnet PM acts in addition to the restoring force FRF: total force F. ges = F PM + FRF.

[0232] The magnetic force FPM is characterized by the fact that the force is high when the valve is open and decreases with increasing stroke s. The magnetic force FPM is at the end of the stroke s=s max is still large enough to perform the usual armature reset. With appropriate design, the return spring 13 can be replaced, provided that the magnetic force FEM1 generated by the coil SP2 and the primary magnetic circuit EMI is large enough to overcome the counterforce generated by the permanent magnet or return spring, which can be achieved by appropriately shaping the characteristic curve of the EM magnetic circuit.

[0233] In addition or as an alternative to the first electromagnetic circuit EMI, a restoring force additional to the first electromagnetic circuit EMI can also be generated by a second electromagnetic circuit EM2. The second electromagnetic circuit EM2 is generated by current in a second coil SP2, with the field passing through the additional armature 6a, which is preferably made of ferromagnetic material. Thus, in this variant, a force is also generated that, like the restoring force FRF of the return spring RF, acts against the hydrodynamic force Fhyd. In this variant, the armature 6 is also mechanically coupled to an additional armature 6a.

[0234] In one embodiment, the return spring RF can be omitted if the additional force device is dimensioned accordingly. A key aspect of the special solenoid valve MV2k is that the total force FGes is essentially linear over the entire stroke. Preferably, the force is increased when leaving the initial position. A characteristic force distribution over the stroke s is shown in Figure 4b. The figure also illustrates that the special solenoid valve MV2k according to the invention results in a significantly different force distribution (cf. FGes) than with valves conventionally used in this area (cf. return force FRF).

[0235] Figure 5a shows a second advantageous embodiment of a special solenoid valve MV2k, which is non-closing, bidirectionally active, and normally open. The special solenoid valve MV2k is suitable for the described use in the first brake module BMI (as inlet valve EV1-EV4) and in the second brake module BM2 (as isolation valve TV1, TV2).

[0236] The special solenoid valve MV2k has the typical design of a solenoid valve with an electromagnetic circuit (EMI). It comprises an armature 6, a valve actuator 7 with a valve tappet 7a, and a valve seat VS. In the exemplary embodiment, an annular permanent magnet PM, which is encased in soft magnetic elements (flux guide), is integrated into the armature 6. The permanent magnet PM is aligned with its poles transverse to the longitudinal direction of the special solenoid valve MV2k. Alternatively, a plurality of correspondingly radially aligned permanent magnets PM can be provided. An electromagnetic field (EMI) is generated by means of an excitation current through a coil SPla, which extends in circular paths within a section of the housing of the special solenoid valve MV2k.The electromagnetic circuit (EMI) extends across the housing, a left leg, passes through a first air gap over the flux conductor in the armature, and closes with a right leg via a second air gap. Both legs are arranged on the housing and are ferromagnetically conductive. The left and right legs are separated by a large air gap, so that the electromagnetic field does not directly connect from the left to the right leg. When energized, magnetic poles form in the legs, which either attract or repel the poles depending on the direction of current through the excitation coil (SPla) and thus, in the direction of magnetic flux, the permanent magnet (PM).

[0237] In the exemplary embodiment, the remaining armature 6 is made of a non-electromagnetically conductive material. For example, it can be made of a cost-effective plastic part, which preferably also includes the valve actuator 7. In the initial position, the armature 6 is positioned such that the flux conductor is closer to the left leg than to the right leg. As a result, the armature 6 experiences a valve-opening force comparable to the force of the magnetic force FPM and / or the restoring force FRF shown in Figure 4a. This makes it possible to dispense with a return spring RF. In addition, the restoring force via the flux conductor is subject to fewer tolerances compared to a return spring RF, since the design of magnetic circuits is highly reproducible.

[0238] In the embodiment shown in Figure 5a, the excitation coil SPla is controlled via a FI bridge (see Figure 6) with four power semiconductors. This allows the magnetic flux direction to be changed by reversing the current direction. Thus, the electromagnetic field EMI can increase or decrease the force acting on the permanent magnet PM. The field can also be reversed so that the special solenoid valve MV2k closes. As a result, the armature 6 can be moved to the right or left in the image plane via current regulation or current control.

[0239] The described embodiment has the advantage that the valve is of very simple construction. The H-bridge comprises, as can be seen from Figure 6, four power semiconductors and the direction of magnetic flux can be determined depending on the circuit of the power semiconductors. If power semiconductors S2 and S3 are switched, a current i1, i2 generates a first magnetic flux direction so that a north pole forms on the left leg and a south pole on the right leg and the armature 6 is magnetically repelled, i.e. the valve is closed. If power semiconductors S1 and S4 are switched, a current i3 generates a second magnetic flux direction so that a south pole forms on the left leg and the armature is retracted, i.e. the valve is opened or held in the open position.The inventive control via an H-bridge allows the restoring force of the permanent magnet PM to be even amplified, resulting in the valve being extremely resistant to closing and also being able to open very quickly. This rapid opening has the advantage that dead times during pressure reduction due to the valve opening process, which are typically around 2 ms, can be reduced to less than 1 ms. This enables rapid pressure reduction without any loss of time, which has a beneficial effect on the ABS control quality and the braking distance. Furthermore, the cross-section of the special solenoid valve MV2k can be controlled very precisely during pressure buildup, and large valve opening cross-sections with the advantage of reduced throttling effect with large valve lifts can be easily realized with this approach.With the inventive control via an H-bridge, the special MV2k solenoid valves can be operated with a variable valve cross-section and current control during both pressure build-up and pressure reduction. This enables particularly quiet and highly precise pressure control during both pressure build-up and pressure reduction.

[0240] In one embodiment, the special MV2k solenoid valve is equipped with a large cross-section, which significantly reduces the throttling effect during pressure buildup. This can shorten the time required to reach the blocking pressure.

[0241] The described special solenoid valves MV2k offer the possibility of dispensing with several outlet valves AV1-AV4, in particular of dispensing with two outlet valves on the wheel brakes RB3, RB4 of a rear axle HA, because with such valves a 2-channel multiplex operation can be implemented very easily.

[0242] Figure 5b shows a diagram illustrating the magnetic force FEM1 acting on the armature 6 (cf. VK for pre-setting force and RK for restoring force) over the travel s. The dashed limit smax is the maximum distance at which the valve tappet 7a closes the special solenoid valve MV2k. If the special solenoid valve MV2k is not energized (i = 0), a relatively high restoring force results in the initial position (s = 0), which decreases over the travel s. However, a restoring force also acts in the closed position (s = smax; valve is closed), preventing the valve from closing unintentionally. If the current is applied with a negative sign (cf. i = i3), a significantly stronger restoring force results over the entire travel s.

[0243] With a weak current with a positive sign (i = i3), a restoring force only occurs in positions close to the initial position. Once this restoring force is overcome, a pre-adjusting force acts, forcing the valve stem into the closed position. With a strong current with a positive sign (i = i3), a pre-adjusting force acts over the entire travel s, allowing the special solenoid valve MV2k to be closed in a controlled manner.

[0244] Figure 7a (abbreviation ESP-X4k,iowv, 4 RB, SK,KP) shows another embodiment of the first brake module BMI, in which the valves USV1, USV2 are omitted without this leading to functional restrictions. The brake module has four circuits, ten solenoid valves, four wheel brakes and two storage chambers Spk . This assumes that the first brake module BMI is operated with a second brake module BM2, which supplies two separate brake circuits BK1, BK2 and has isolation valves TV1, TV2 in the form of special solenoid valves MV2k (e.g. as shown in Figure 2b). The isolation valves TV1, TV2 then take over the function of the valves USV1, USV2, particularly during ESP interventions. To implement this solution, an additional interface between the brake modules BMI, BM2 is necessary.The approach has the advantage that the throttle resistances between the pressure generator DV2 of the second brake module BM2 and the wheel brakes RB1-RB4 are reduced, making the system even more responsive, which has a positive effect, for example, during emergency braking.

[0245] Figure 7b (abbreviation ESP-X4k.8Mv.4 RB. SK. KP) shows a first BMI brake module that omits the USV1, USV2, and HSV1, HSV2 valves. The brake module has four circuits, eight solenoid valves, four wheel brakes RB1-RB4, two accumulator chambers Spk, and a piston pump KP. Two check valves RV1, RV2 are provided to implement the functions of the HSV1, HSV2 valves, which connect to the reservoir VB. This leads to a further cost reduction without any functional limitations and without limiting the range of functions.

[0246] Figure 8a (abbreviation ESP-X2k.4Mv. 2 RB. SK.KP) shows an embodiment that is a modification of the embodiment shown in Figure 7b. Only four valves (two inlet valves, two outlet valves) are required. A first brake module can be used for a two-wheeled vehicle or one axle of a multi-axle vehicle. It has connections for exactly two wheel brakes RBI, RB2, whereby each wheel circuit can be isolated separately via the special solenoid valves MV2k, which are used as isolation valves TV1, TV2.

[0247] If a wheel brake RBI, RB2 fails, the remaining wheel brake circuit can still be operated and braking torque can be built up or reduced. This first brake module BMI preferably also provides an interface IntBM1 to the primary control unit M-ECU so that target specifications for wheel-individual braking torque interventions can be specified directly via the primary control unit M-ECU. The first brake module BMI functions independently with standard pressure setting mode (pressure control method A); with an additional pressure supply DV2, pressure control method B can also be used. At the brake module BMI, either a separately designed pressure generator DV2 or a second brake module BM2 can be hydraulically connected to port A1, A2, or an SHZ can be connected. Likewise, as shown in Figure 2b, it is possible to switch between a standard pressure setting mode and a special pressure setting mode I in ABS operation.

[0248] Figure 8b (abbreviation ESP-X2k.4Mv, 2 RB, VB, MKPD) shows another embodiment of the first brake module BMI for two wheel brakes RB1, RB2, where the pressure generator is a pump with multiple pistons. Pressure reduction occurs via the outlet valves AVI, AV2 directly into the reservoir VB. This has the control-related advantage that control at low pressures, particularly when controlling on snow and ice, can be significantly improved because the back pressure of the storage chamber SpK does not limit the pressure gradients during pressure reduction. In this embodiment, the special pressure setting mode I is not required.

[0249] The first brake module BMI preferably also provides an interface IntBMl to the primary control unit M-ECU, so that VMC target specifications for wheel-specific braking torque interventions can be specified directly via the primary control unit M-ECU. The first brake pressure module BMI operates independently with pressure control method A; with an additional pressure generator DV2, pressure control method B can also be implemented.

[0250] Figure 8c (abbreviation ESP-X2k.4Mv. 2 RB. VB. RP) shows an embodiment similar to that shown in Figure 8a with a first brake module BMI for two wheel brakes. A rotary pump RP is provided as the pressure generator DV1, by means of which pressure can be built up and, by reversing the direction of rotation, also reduced. The special solenoid valves MV2k, arranged as inlet valves EVI, EV2 and connected to the wheel brakes RBI, RB2, are equipped with redundant excitation coils and redundant drivers. In general, such redundant equipment is possible in all embodiments according to the invention.

[0251] The two outlet valves AVI, AV2, each assigned to a wheel brake RBI, RB2, are hydraulically connected to the reservoir VB for effective pressure reduction. This embodiment is very advantageous in that it offers several degrees of freedom for pressure reduction, which can be used either to improve availability in the event of a partial failure or to improve the control and pressure regulation options. Thus, pressure reduction can occur completely independently – from the perspective of the first brake module BMI – via the outlet valves AVI, AV2. Furthermore, pressure buildup and pressure reduction can be achieved using an external pressure generator DV2, which is provided separately or as part of a second brake module BM2. This embodiment is therefore particularly suitable for use as a cost-effective axle module, preferably centrally controlled.

[0252] In general, the rotary pump RP can be used in all described embodiments, either additionally or alone, as the first pressure generator DV1 or as the second pressure generator DV2. When used in the first brake module BMI as the first pressure generator DV1, the check valve RV1 (see, for example, Figure 3b) between the pump and the reservoir VB can be omitted. An advantage of pressure reduction via the rotary pump RP is that the pressure reduction gradients are not limited by the backpressure of the storage chamber Spk and can be used to improve ABS control performance at low pressures, even without an external pressure generator DV2.

[0253] The first brake module BMI according to Figure 3b preferably also provides an interface IntßMi to the primary control unit M-ECU, so that target specifications from VMC for wheel-specific braking torque interventions can be specified directly via the primary control unit M-ECU. The first brake module BMI functions independently with pressure control method A or special pressure setting mode II (rotary pump acts as a pressure sink). With an additional pressure generator DV2, pressure control method B (special pressure setting mode I) can also be implemented.

[0254] Figure 9 shows an embodiment similar to that shown in Figure 8a. In this embodiment, a (single) hydraulic connection is provided for a second brake module BM2. The advantage of the four-circuit design is utilized by using the special solenoid valves MV2k on (all) four wheel brakes RB1-RB4, eliminating the need for brake circuit separation.

[0255] The exemplary embodiment preferably also provides an interface (not shown) Int-BM1 to a central control system, preferably in the form of the primary control unit M-ECU, so that target specifications for wheel-specific braking torque interventions can be specified externally. The described first brake module BMI functions autonomously with pressure control method A and can be expanded with a second brake module BM2 to include pressure control method B (special pressure adjustment mode I).

[0256] Figure 10 shows a further embodiment, a modification of the embodiment shown in Figure 9. This embodiment does not have a storage chamber Spk. For pressure reduction, the wheel brakes RB1-RB4 are hydraulically connected to the reservoir VB via outlet valves AVI - AV4. Only one hydraulic connection is provided for connecting a second brake module BM2. The hydraulic structure is similar to that of the embodiments shown in Figures 8b and 8c. However, this first brake module BMI is designed for four wheel brakes. This embodiment is suitable as a central hydraulic pressure regulator controlled by a central computer, for example, the primary control unit M-ECU.

[0257] This first BMI brake module optionally has an IntßMi interface (not shown) to the primary control unit, allowing target values ​​for wheel-specific braking torque interventions to be specified externally. It operates independently with pressure control methods A and B.

[0258] Figure 11 shows an example of a first intake valve EVI, as can be used in some or all of the described embodiments. The intake valve EVI is designed as a special solenoid valve MV2k and has redundant coils, each powered by a driver. The first driver (left) is electrically connected to the secondary control unit S-ECU1 of the first brake module BMI, in which the respective intake valve is used. The second driver (right) is connected to two interfaces Int2BM and INTBM1, so that it can be controlled by at least one of the secondary control units S-ECU2a of the second brake module BM2 and the primary control unit M-ECU.

[0259] In one embodiment, the secondary control unit S-ECU1 implements PWM control with pulse width modulation, i.e., voltage clocking. A simple switch is sufficient for this. Control by the primary control unit M-ECU or by the second brake module BM2 is preferably carried out by means of current control i=f(t). The H-bridge described above can be used for this. The H-bridge can control the temporal current profile and provides more degrees of freedom, particularly for valve cross-section control with a variable cross-section both during pressure build-up and, with appropriate design, during pressure reduction. This allows pressure to be built up and reduced quietly. Depending on the embodiment, the H-bridge can be used as the first or second driver. Alternatively, both drivers can be operated via PWM control.

[0260] Figure 12 shows an exhaust valve AVI as it can be used in one or all of the described embodiments. The exhaust valve AVI has redundant coils, each powered by a driver. The first driver (left) is electrically connected to the secondary control unit S-ECU1 of the first brake module BMI, in which the respective exhaust valve AVI is used. The second driver (right) is connected to two interfaces Int2BM and INTBM1, so that it can be controlled by at least one of the secondary control units S-ECU2a of the second brake module BM2 and the primary control unit M-ECU.

[0261] The exhaust valve AV is preferably operated in a time control system in which the opening time is controlled via the voltage U=f(t).

[0262] To illustrate the functionality of the brake modules BMI and BM2 from Figure 3a, Figures 13a and 13b show a pressure buildup (Figure 13a) and a pressure reduction (Figure 13b) via the second brake module BM2. The respective volume flows are marked schematically. In the upper right corner, pressure diagrams over time (t) are shown, visualizing the pressure curve in the wheel brakes RB1 and RB2.

[0263] In the embodiment according to Figure 13a, the pressure build-up occurs either sequentially according to pressure control method B (MUX) in the multiplex / PPC method with a delay time Atmux or by means of pressure control method A (EVPWM), in which the pressure build-up occurs simultaneously via a pre-pressure control in several wheel brakes RBI, RB2. In the latter method, one valve, e.g. the inlet valve EVI, is preferably open and the other valve, e.g. the second inlet valve EV2, is operated using PWM control. Alternatively, both inlet valves EVI, EV2 can be operated with different PWM frequencies or

[0264] Current profiles for different valve opening cross-sections are operated in order to set different pressures in the wheel brakes RBI, RB2 for a given pre-pressure. For pressure reduction according to Figure 13b, the pressure reduction at the wheel brakes RB1 and RB2 is shown as an example. The pressure reduction takes place either sequentially according to pressure control method B (MUX) in the multiplex / PPC process in a closed hydraulic circuit via the special solenoid valves MV2k with a delay time Atmux or using pressure control method A (standard pressure setting mode) with an open hydraulic circuit via the outlet valves AVI, AV2. In this way, the pressure from a wheel brake RB1 can be reduced using the multiplex / PPC process and the pressure in the wheel brake RB2 can be built up in parallel via outlet valves. If a very rapid pressure reduction is required, the pressure can also be reduced in parallel via outlet valves and special solenoid valves using the special pressure setting mode II (not shown).If an exhaust valve fails, the system can switch from pressure control method A to the multiplex / PPC method on a wheel brake. These alternatives and degrees of freedom allow for excellent control performance for every critical driving situation, and redundant 4-channel operation is also possible.

[0265] Figure 14 shows the pressure reduction in a configuration of the brake modules BMI, BM2, as explained in Figure 3b. The volume flow is marked schematically. In the upper right corner is a pressure diagram over time (t), which visualizes the pressure curve in the wheel brakes RBI, RB2, RB3, and RB4.

[0266] According to the control strategy visualized here, pressure reduction according to pressure control method B can occur in the multiplex / PPC method with a delay time Atmux or via pressure control method A. In the MUX method, the target pressure, which is lower than the pressures in the wheel brakes RB1-RB4, is set via the piston-cylinder unit. The delay time Atmux can be avoided by the simultaneous reduction via the outlet valves AV1-AV4 into the accumulator chamber without a delay time. Thus, no restrictions are to be expected in critical driving situations due to the control. In addition, the first brake module BMI can be optimized with regard to noise by controlling large pressure gradients with the MUX method, thus avoiding noise-generating vibrations, and implementing small pressure gradients with pressure control method A.

[0267] Figure 15 shows a solution according to the invention with two pressure supply units in the simplest and most cost-effective embodiment. Similar to Figure 10, the BMI brake module is equipped with only eight solenoid valves, with all wheel inlet valves being designed with special solenoid valves, i.e., a BMI brake module with four wheel brake circuits is created here. Instead of an electric motor-driven piston-cylinder unit, an electric motor-driven rotary pump is used as the second pressure supply unit. Due to the design with four wheel brake circuits, only one hydraulic connection to the BMI brake module is required. The BMI brake module functions independently but is preferably supported by a third BM3 brake module in normal control.

[0268] In standard pressure setting mode, pressure is reduced via outlet valves into the reservoir and, in parallel or alternatively, via the rotary pump. By rotating the rotary pump in the appropriate direction, the rotary pump acts as a pressure sink during pressure reduction. In addition to high fault tolerance, this design offers many degrees of freedom, in particular the option of switching from standard pressure setting mode (pressure build-up via inlet valves and pressure reduction via timing of the outlet valves) to special pressure setting mode I and / or special pressure setting mode II. If the first brake module BMI fails, the rotary pump takes over the function of pressure build-up, with the wheel pressure control valves being controlled simultaneously via a primary control unit M-ECU or another secondary control unit S-ECU2a, S-ECU2b via the communication interfaces (Int2BM, IntBMl) shown in Figure 11 and Figure 12.

[0269] In the preceding description, the special solenoid valve was (predominantly) described as a special solenoid valve with an additional force device comprising a permanent magnet and / or a second excitation coil and arranged to provide at least one retaining force acting on the valve actuator or the valve tappet. In at least some of the described embodiments, the special solenoid valve can be any suitable pull-tight solenoid valve. Thus, it is advantageous to achieve the pull-tightness by providing at least one throttle, which ensures that the volume flow remains so low that the valve does not close.

[0270] In general, the closing effect can be limited by a pressure difference limitation in the control of the pressure supply unit or preferably by means of a throttle (not shown), wherein the throttle is preferably installed in front of the armature connection of the valve connection in a hydraulic line.

[0271] In some versions of the special solenoid valve, the return spring RF can be omitted.

[0272] Furthermore, in at least one of the described embodiments, the driving dynamics system can be designed in such a way that a simple application of the core functions via the primary control unit M-ECU is possible, in particular due to the high computing power, automated application of the functions during development. In at least one of the described embodiments, vehicle operation can be supported using learning algorithms or artificial intelligence (AI). When using AI, the primary control unit M-ECU can take on the role of the application engineer, which is not possible with state-of-the-art microcontrollers (i.e. one in the control unit of a braking system) due to the very limited power and limited memory.The central computer records measurement data during vehicle operation, evaluates it, and applies various functions, in particular the safety-critical functions ABS, ESP, and AEB, during vehicle operation or when the vehicle is stationary, when the vehicle is not moving and therefore the adaptation is not time-critical. Therefore, the adaptation takes place particularly after vehicle operation when the vehicle is parked. Here, the preferred design as a closed hydraulic system with primarily pressure build-up and pressure reduction via bidirectional valves by means of the pressure supply unit has the great advantage, since the non-linear relationships can be mapped by suitable sensors via characteristic maps (e.g. pressure-volume characteristic, relationship between motor current and brake pressure, relationship between brake pressure and deceleration when the wheel brake heats up), during operation for the recording of environmental influences (e.g.Air in the system, heating of the wheel brake). If the nonlinear relationships are mapped to mathematical functions or characteristic maps, automatic calibration of an electrohydraulic brake system is also possible. If the AI ​​approach is consistently implemented in a hydraulic brake system (EHB), the advantage of the easily adjustable or controllable electromechanical brake (EMB) disappears, and the advantages of the lower manufacturing costs of the hydraulic brake system become effective, because the disadvantages in the calibration costs largely disappear.

[0273] List of reference symbols:

[0274] M-ECU primary control unit, central computer

[0275] R1-R4 wheel vRl-vR4 wheel speed sensors

[0276] RB1-RB4 wheel brake

[0277] BK1, BK2 brake circuit

[0278] Al, A2 connection

[0279] BMI First Brake Module

[0280] BM1BE assembly of the first brake module

[0281] DV1 pressure generator

[0282] M engine

[0283] P Pump unit

[0284] Spk storage chamber

[0285] S-ECU1 Control unit of the first brake module

[0286] RP rotary pump

[0287] KP piston pump

[0288] MKP multi-piston pump

[0289] BM2 Second brake module

[0290] BM2BE assembly unit of the second brake module

[0291] DV2 pressure generator

[0292] S-ECU2a Control unit of the second brake module

[0293] S-ECU2b Control unit of the second brake module

[0294] TV1, TV2 isolation valve

[0295] BM3 Additional brake module RV, RV1, RV2 check valve

[0296] AVI, AV2, AV3, AV4 exhaust valve

[0297] EVI, EV2, EV3, EV4 Inlet valve HSV1, HSV2, USV1, USV2 Valves of the ESP unit MV2k Special solenoid valve for pressure build-up and pressure reduction

[0298] TM1 first electric traction motor to drive a vehicle axle or a wheel

[0299] TM2 second electric traction motor to drive a vehicle axle or a wheel

[0300] TM3 third electric traction motor for driving a vehicle axle or a wheel

[0301] VB storage container

[0302] VA front axle

[0303] HA rear axle

[0304] FRF restoring force via a spring

[0305] FPM magnetic force

[0306] FEM1, FEM2 magnetic force

[0307] PM permanent magnet

[0308] EMI, EM2 magnetic circuit

[0309] RF return spring

[0310] SP1, SPlat, SPlb, SP2 excitation coil

[0311] 6 anchors

[0312] 6a Additional anchor

[0313] 7 Valve actuator

[0314] 7a valve tappet

[0315] 10 Pole plate

[0316] 13 Return spring

[0317] VS valve seat

[0318] AR anchor room

[0319] MSI, MS2 solenoid coil

[0320] S air gap

[0321] S1-S4 power semiconductors

Claims

Driving dynamics system for a vehicle with wheels and method for adjusting a brake pressure CLAIMS 1. Driving dynamics system for a wheeled vehicle (R1-R4), comprising: - a primary control unit (M-ECU) for detecting and / or generating steering commands and braking commands; - at least two hydraulically actuated wheel brakes (RB1-RB4), each assigned to a wheel (R1-R4); - at least one electric traction motor with traction motor control unit, wherein the traction motor (TM1, TM2) is arranged to drive at least one of the wheels (R1-R4), wherein the primary control unit is communicatively connected to a traction motor control unit to control the traction motor (TM1, TM2) to implement the steering commands and braking commands; - at least one (first) electro-hydraulic pressure supply unit (BMI) with o at least one electric motor-pump unit: o at least two connections for connecting the wheel brakes (RB1-RB4); o electrically actuated wheel brake pressure adjustment valves or brake pressure adjustment valves (AV1-AV4, EV1-EV4), and o a first secondary control unit (S-ECU1); wherein at least one of the hydraulically actuated wheel brakes (RB1-RB4) is assigned a brake pressure adjustment valve in the form of a special solenoid valve (MV2k), in particular one that is resistant to closing, and an outlet valve (AV1-AV4), characterized in that the driving dynamics system, in particular the primary control unit (M-ECU), is designed to reduce pressure from the at least one hydraulically actuated wheel brake selectively via the assigned outlet valve or via the special solenoid valve (MV2k).

2. Driving dynamics system according to claim 1, characterized in that the at least one brake pressure adjusting valve is a special solenoid valve (MV2k) with an electromagnetic drive with a first excitation coil (SP1, SPla), via which a valve actuator (7) or valve tappet (7a) can be adjusted between an open valve position and a closed valve position, wherein the special solenoid valve (MV2k) has an additional force device which comprises a permanent magnet (PM) and / or at least one second excitation coil (SPlb, SP2) and which is designed to provide at least one force acting on the valve actuator (7) orthe retaining force (FEM2, FPM) acting on the valve tappet (7a) is arranged; and / or the primary control unit (M-ECU) is designed to control the special solenoid valve (MV2k) and the first pressure supply unit (BMI) at least in a selected braking mode such that pressure is reduced from the wheel brake (RB1-RB4) assigned to the special solenoid valve (MV2k) when the special solenoid valve (MV2k) is open.

3. Driving dynamics system according to one of the preceding claims, characterized in that the primary control unit (M-ECU) is designed to control the associated special solenoid valve (MV2k) and outlet valve (AV1-AV4) at least in a selected braking mode such that brake fluid is simultaneously discharged from the wheel brake via the associated special solenoid valve (MV2k) and the associated outlet valve (AV1-AV4).

4. Driving dynamics system according to one of the preceding claims, characterized by: at least one second pressure supply unit (BM2), preferably comprising a piston-cylinder unit or a rotary pump, which is arranged to provide brake fluid at at least one inlet of the first pressure supply unit for a first brake circuit (BK1) and a second brake circuit (BK2), wherein preferably at least one isolating valve is provided for isolating the first and / or second brake circuit. Driving dynamics system according to one of the preceding claims, characterized in that the first pressure supply unit (BMI) is (directly) connected to exactly two wheel brakes (RB1-RB4), wherein the exactly two wheel brakes (RB1-RB4) brake wheels on a first axle and / or a further pressure supply unit (BM3) is provided which is (directly) connected to at least two wheel brakes (RB1-RB4) on a second axle. Driving dynamics system according to one of the preceding claims, characterized in that the special solenoid valve (MV2k) is designed to be open when de-energized and is arranged such that a valve seat of the special solenoid valve is (directly) connected to at least one of the wheel brakes (RB1-RB4).Driving dynamics system according to one of the preceding claims, characterized in that the primary control unit (M-ECU) is designed to detect a failure of at least one wheel brake circuit, comprising one of the wheel brakes (RB1-RB4), and to close the special solenoid valve (MV2k) assigned to the wheel brake (RB1-RB4) to disconnect the wheel brake circuit. Driving dynamics system according to one of the preceding claims, characterized in that the first pressure supply unit (BMI) comprises a rotary pump that is connected and designed to build up and reduce pressure in the wheel brakes (RB1-RB4). Driving dynamics system according to one of the preceding claims, in particular according to claim 4, characterized in that a / the special solenoid valve (MV2k), in particular the special solenoid valve (MV2k) assigned to the second pressure supply unit (BM2), is arranged such that a valve seat of the special solenoid valve. (directly) connected to an input of the first pressure supply unit (BMI). Driving dynamics system according to one of the preceding claims, in particular according to claim 4 or 9, characterized in that at least one of the special solenoid valves (MV2k) is controlled during pressure reduction to provide a variable valve opening cross-section, in particular by PWM control or current control. Driving dynamics system according to one of the preceding claims, characterized in that the first secondary control unit (S-ECU1) and / or second secondary control unit (S-ECU2a, S-ECU2b) and / or Actuators of the first and / or second pressure supply unit (BMI, BM2) and / or Sensors of the first and / or second pressure supply unit (BMI, BM2) are communicatively connected, in particular via communication interfaces (IntBM1, IntBM2), to the primary control unit (M-ECU) in order to implement steering commands and / or braking commands. Vehicle dynamics system according to one of the preceding claims, in particular according to claim 11, characterized in that the primary control unit (M-ECU) is designed to - to implement a wheel brake-specific pressure control by controlling at least one of the special solenoid valves of the first pressure supply unit and / or the at least one second pressure supply unit, and / or - to detect a wheel circuit failure by measuring pressure when the special solenoid valve of the first pressure supply or an inlet valve is closed, and / or - by closing at least one of the isolating valves (TV1, TV2), to isolate a defective brake circuit, and / or - to implement an (axle-wise) ABS by controlling at least one of the isolating valves (TV1, TV2) and alternating pressure build-up and pressure reduction via the second pressure supply unit, and / or - by controlling at least one of the special solenoid valves (MV2k) and in particular outlet valves of the first pressure supply unit and by alternating pressure build-up and pressure reduction, to implement a wheel-individual ABS via the second pressure supply unit (BM2), and / or - during braking using the at least one traction motor, to distribute a braking torque generated by the second pressure supply unit (BM2) axle by axle by controlling the special solenoid valve (MV2K) assigned to the second pressure supply unit, and / or - to implement an (automatic) emergency braking by parallel control of the traction motors (TM1, TM2) and at least the first pressure supply unit (BMI). Driving dynamics system according to one of the preceding claims, in particular according to claim 2, characterized in that the electromagnetic drive (EMI) is redundantly designed with at least one first solenoid valve driver and a second solenoid valve driver, wherein the secondary control unit (S-ECU1) for controlling the at least one special solenoid valve (MV2k) with the first solenoid valve driver and the primary control unit (M-ECU) for controlling the at least one special solenoid valve (MV2k) is communicatively connected to the second solenoid valve driver.

14. Driving dynamics system according to one of the preceding claims, characterized in that the primary control unit (M-ECU) is designed to at least temporarily adjust a brake pressure in at least a selection of the wheel brakes (RB1-RB4) in a multiplex and / or a PPC method.

15. Driving dynamics system according to one of the preceding claims, characterized in that the primary control unit (M-ECU) is designed to implement the method at least according to claim 16.

16. A method for adjusting a brake pressure in at least one wheel brake of a brake system, preferably via inlet valves for admitting brake fluid into wheel brakes and outlet valves for discharging brake fluid from the wheel brakes (RB1-RB4), the method comprising: - Determining that pressure is to be released from at least one of the wheel brakes (RB1-RB4), namely a target wheel brake; - selecting a pressure reduction mode from a first pressure reduction mode and a second pressure reduction mode; - if the first pressure reduction mode is selected, opening at least one of the outlet valves associated with the target wheel brake to implement the pressure reduction; - when the second pressure reduction mode is selected, keeping the outlet valve assigned to the target wheel brake closed and opening at least one of the inlet valves assigned to the target wheel brake and generating a differential pressure in an (external), preferably second, pressure supply unit in order to implement the pressure reduction from the target wheel brake via the inlet valve.

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