Brake system

Abstract

To provide an improved brake system.SOLUTION: A brake system comprises: a brake pedal (1); a first piston-cylinder unit (THZ) having two pistons (12 and 16) for supplying brake circuits (BK1 and BK2) with a pressure medium from a valve device (FV), where the first piston-cylinder unit (THZ) can drive one of the pistons (16) by a drive device; a second piston-cylinder unit having an electric motor drive body (8), a transmission device (7), and at least one piston (10) to supply at least one of the brake circuits (BK1) with the pressure medium via the valve device; and a motor pump unit (ESP) with a valve device (HSV, USV, EV, and AV) to supply the brake circuits with the pressure medium. The brake system also comprises a stroke simulator (WS) having a pressure chamber or a working chamber which is connected to the first piston-cylinder unit.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a brake system in the preamble of claim 1. [Background technology]

[0002] As a trend toward autonomous driving (AD) vehicles, there is a high demand for brake systems, both from the perspective of fault tolerance and from the perspective of redundancy for brake pressure generation, power supply, and computer functions (ECU). So-called one-box and two-box systems are gaining popularity. The latter consists of an electric brake booster (BKV), also known as an e-booster, and an ESP system. This system provides redundancy for brake pressure generation by an electric motor and electronic control unit (ECU) in addition to the e-booster and return pump, which are equipped with an electric motor and ECU.

[0003] Known solutions to this problem are characterized by their relatively long overall length and heavy weight.

[0004] International Publication No. 2011 / 098178 (hereinafter referred to as Modification A, or Follow-Up Booster, or e-Booster) describes a solution to this problem, comprising a coaxial drive unit in which an electric motor acts on an HZ piston (= main cylinder piston) via gears and a piston. BKV control is performed via an electric element and reaction disc acting as a so-called follow-up booster, and the pedal stroke is determined by the brake pressure and the volume absorption of the brake system. This requires a long pedal stroke in the event of brake fade or brake circuit malfunction.

[0005] International Publication No. 2009 / 065709 (hereinafter referred to as Modification B, or Follow Booster, or e-Booster) also shows the e-Booster as a Follower BKV. Here, BKV control is performed through pedal stroke and pressure. An independent pressure supply unit having an electric motor and plunger acts on the HZ piston via an amplified piston.

[0006] International Publication No. 2012 / 019802 (hereinafter, Modification C) shows a configuration similar to International Publication No. 2011 / 098178, having a coaxial drive unit in which an electric motor acts on an HZ piston via gears and a piston. Here, an auxiliary piston cylinder unit acting on a stroke simulator piston (WS) is used. Therefore, the pedal stroke is independent of fade phenomena and brake circuit malfunctions. However, this becomes very complex and the structure becomes long.

[0007] DE10 2009 033 499 (hereinafter also referred to as Modification D) illustrates a brake booster (BKV) with a further ESP unit having a hydraulically driven booster piston and an external pressure supply. This configuration, having four or five pistons and six solenoid valves (MV), is complex and disadvantageous in terms of length. A non-hydraulic operated stroke simulator (WS) is located in the piston-cylinder unit upstream of the main cylinder and cannot be braked or switched via the solenoid valves (MV).

[0008] All of the above-mentioned solutions incorporate redundant brake force amplification (BKV) functions. This is because, in the event of a malfunction in the BKV motor, the ESP unit equipped with a pump will ensure braking functionality in automatic driving mode, similar to the support function using a vacuum BKV.

[0009] As described in the applicant's International Publication No. 2010 / 088920, if the ESP motor malfunctions, the ABS will function through pressure adjustment made possible by the BKV motor. However, this only enables common pressure control for all four wheels and does not optimize the braking distance.

[0010] All known one-box systems have a so-called stroke simulator (especially for brake-by-wire systems) to enhance pedal stroke characteristics.

[0011] Known systems with e-boosters and ESPs have only one redundant configuration in the pressure supply unit (DV), i.e., if the e-booster fails, the redundant pressure supply unit (DV) uses the redundant output for the brake booster (BKV) provided by the ESP, and higher safety requirements are not considered. Also, if the ESP fails, sufficient ABS function is ensured by the e-booster. [Overview of the Initiative] [Problems that the invention aims to solve]

[0012] Building upon prior art, the object of the present invention is to provide an improved braking system.

[0013] The present invention is based on the objective of creating a braking system for use in autonomous driving operations (hereinafter referred to as AD) and / or electric / hybrid vehicles that has increasingly powerful regenerative output (energy recovery through braking via the generator / or drive motor during generator operation), and which is a significant improvement over prior art.

[0014] Furthermore, a cost-effective braking system for autonomous driving has been developed, which not only meets extremely high safety requirements but also all the necessary redundancy.

[0015] Furthermore, when the ESP fails, both sufficient functions of the ABS in terms of braking distance and stability and sufficient functions regarding regeneration can be achieved using the braking system.

Means for Solving the Problem

[0016] This object is solved by the present invention having the characterizing part of claim 1.

[0017] In particular, the improvement is characterized in that the structure of the brake booster has a very small number of simple components (for example, a valve with only an opening / closing operation) with low accuracy requirements, resulting in high cost efficiency, a very short and thin structure, and in particular, enabling certain pedal stroke characteristics together with strong regeneration.

[0018] Advantageous embodiments or structures of the present invention are included in further claims, drawings, and figure descriptions, which are hereby incorporated by reference.

[0019] According to the means for solving the problem by the present invention, its embodiments, and structures, a braking system having a very short structure and beneficial pedal characteristics is formed.

[0020] In particular, a turbo box system (hereinafter also referred to as the turbo box system and as the X-booster and ESP / ABS unit) having an electric brake booster connected to a standard ESP unit via two hydraulic lines is formed according to the present invention. The brake booster has pedal characteristics independent of the volume absorption and regeneration degree of the braking system.

[0021] Furthermore, the present invention achieves a compact structure of a brake booster with a small box volume. This brake booster is extremely short and thin, and has, for example, a lot of redundancy against pressure generation, power supply, and malfunctions of the pump motor of the ESP unit, and also includes an ABS function whose performance is limited when a malfunction of the ESP unit occurs. In an emergency operation without ESP, the ABS function should include at least individual adjustment ( "selectro" pressure adjustment) for each axle in order to improve the braking distance.

[0022] The installation space of the unit compartment is becoming smaller and smaller. Therefore, the dimensions of the brake unit should be made as small as possible, especially with respect to the width and length. This compact structure is made possible on the one hand by separating the master cylinder (HZ) piston from the motor drive body, and on the other hand by the particularly short master cylinder (HZ) according to International Publication No. WO 2016 / 023994 by the applicant. This particularly short master cylinder will be described below together with a pressure supply unit (hereinafter, pressure supply unit or DV) arranged in parallel and consisting of an electric motor having a piston drive body.

[0023] The pressure supply unit (DV) is only effective up to a wheel lock limit of 80 to 100 bar maximum. For higher pressures (for example, for driver assistance functions), the ESP pump operates. Therefore, this can be realized using the problem-solving means according to the present invention rather than the modification example A of the prior art described above, because the ESP pump function does not affect the pedal feel because the brake pedal is disengaged.

[0024] The purpose of the X booster equipped with DV is to supply the corresponding liquid volume at a maximum pressure of 80 to 100 bar in order to increase the pressure of the ESP pump.

[0025] This has the advantage that the X-Boost pressure supply unit DV, equipped with a drive motor or engine, only needs to be designed for low mechanical loads, and that electric motors require only lower torque, for example, 80-100 bar, compared to the ESP pump's maximum pressure of approximately 200 bar. This allows for the use of cost-effective ball screw drive units (KGTs) or trapezoidal spindles with plastic nuts.

[0026] Secondly, the pump (ESP pump) can be designed so that the pump motor is only loaded with a differential pressure of 200 bar - (80-100) bar (=100-120 bar). Conventional ESP pumps, for example, can be loaded with a maximum pressure of 200 bar. This advantage results in a beneficial reduction in the output or torque of the pump motor.

[0027] In this case, there are further possibilities for interconnection. The ESP pump can not only operate in conjunction with the X-Boost (80-120 bar) but can also operate when quickly operating the pedals at, for example, 20 bar. This results in either a more rapid pressure increase relative to the lock time (TTL) or a further reduction in the motor output of the X-Boost's DV.

[0028] In the case of ESP pumps, this connection of series and / or parallel pumps requires a two-circuit gear pump or, in the case of piston pumps, an independent eccentric for each piston.

[0029] In terms of pedal characteristics, for example, in the event of a brake circuit malfunction, retrospective effects from volume absorption should be eliminated. On the other hand, when the ABS function is used intermittently at the discretion of the driver, it must be possible to produce desirable pedal feedback, such as small pedal movements. Moving the pedals in parallel can also signal a malfunction, such as a brake circuit malfunction, to the warning lights.

[0030] Various solutions can be envisioned for the pedal stroke simulator. Across the entire pressure range (150-200 bar), the pedal stroke simulator must exhibit good pedal stroke characteristics, for example, with a flat characteristic curve up to 30 bar, and then progressively increasing, without being affected by whether the X-boost or ESP unit supplied pressure. In the embodiment of the e-boost as a follow-up booster (modification A of the prior art), the pedal force characteristic curve changes significantly when transitioning from the e-boost to the ESP, requiring a lot of software work for the PWM operation of the valve necessary for this. This does not apply to the solution of the present invention, because the operation of the ESP pump does not affect the pedal characteristics because the pedal is disconnected via the stroke simulator.

[0031] To reduce the volume of the structure, by using a return spring (18) in the flat portion of the pedal stroke characteristic curve, the volume of the piston stroke simulator can be made smaller, as shown in the present applicant's International Publication No. 2013 / 072198, cited herein, so that it corresponds only to the progressive portion of the characteristic curve.

[0032] The stroke simulator can preferably be a piston simulator (WS) connected to the working chamber of an auxiliary piston via a hydraulic connection line, and / or a plunger simulator connected to the working chamber of a second piston (SK). When a plunger simulator is provided, a control pressure dependent on the pedal stroke acts on the plunger.

[0033] It would also be advantageous if the stroke simulator could be turned off in further development, was not active in the first range, and the brake pedal force was determined exclusively by the return spring and by the return spring and stroke simulator piston in the second range.

[0034] Furthermore, a switching valve may be connected upstream of the stroke simulator to switch the stroke simulator on or off as needed. However, if the switching valve is not connected upstream of the stroke simulator, the switching valve (WA) must be located in a branch line that branches from the pressure chamber or working chamber of the auxiliary piston connected to the stroke simulator to the storage container.

[0035] If pressure-volumetric characteristics are used for pressure supply control and diagnosis, that is also advantageous.

[0036] As described or illustrated in the applicant's International Publication No. 2016 / 023994, another possible implementation of a pedal stroke simulator is a THZ (=tandem main brake cylinder) having a plunger but without a piston stroke simulator, which the present patent references herein in this regard. In this case, the control pressure to the BKV, which depends on the pedal stroke, acts on the plunger to produce a pedal feedback effect.

[0037] Depending on the pedal position, pressure is sent from the piston of the pressure supply unit to the SK piston of the main brake cylinder (T)HZ, which generates brake pressure. The pressure supply unit consists of an electric motor that drives the piston via a spindle. Both a ball screw drive unit (KGT) and a trapezoidal spindle with a nut can be used as the transmission device. The latter is cheaper and quieter, but less efficient and has an automatic locking mechanism. The latter has the advantage that, for example, if an engine malfunction occurs in the pressure supply unit DV, the piston remains in place, and therefore the fluid volume in the brake circuit does not increase due to the influence of brake pressure.

[0038] In the case of a ball screw drive (KGT), an additional shut-off valve must be used to address this malfunction. Liquid is drawn from the storage container (VB) via an intake valve or a piston sleeve seal with a breather hole, similar to the main cylinder (HZ).

[0039] The flow path to the piston stroke simulator can be closed by a solenoid valve (WA), and in the event of a malfunction (DV) in the pressure supply unit, pedal force acts on the main cylinder (HZ), generating a so-called fallback level (RFE) brake pressure. In the absence of the valve (WA), the pedal stroke at the fallback level (RFE) is extended by volume absorption in the piston stroke simulator (WS).

[0040] The interconnection of the X-Boost and ESP units, along with redundant power supplies, provides two redundant systems for pressure generation, so the fallback level (RFE) is only effective during towing. It is only effective under practically extreme loads, such as when the vehicle's transmission may be interrupted. This allows for greater flexibility in the system and piston structure, for example, by eliminating the need for a WA solenoid valve.

[0041] One possibility for pad clearance control is to use a strong rollback seal in the wheel brake to return the pads to their original position. This seal can form the required clearance, particularly due to the deformation energy stored within it. The stored deformation energy generates a restorative force that pulls the brake pads away from the brake disc (creating clearance or gap) as soon as the pressure in the brake circuit no longer increases. This is preferably possible in the present invention because it does not affect the brake pedal due to the disconnection.

[0042] The X-Boost and ESP units have separate power supplies; for example, the ESP is connected to a 12V battery, and the X-Boost is connected to a DC / DC converter in a multi-voltage vehicle electrical system. Alternatively, both the X-Boost and ESP units can be connected to both a 12V battery and a DC / DC converter. Therefore, both modules of the two-box brake system have redundant power supplies.

[0043] The problem-solving means according to the present invention has the following further advantages over the modification A of the prior art. I. If the brake circuit malfunctions, the pedals will not stop working. II. In the event of an ESP motor failure, the pressure can be controlled per axle or per wheel, which allows for a significant reduction in braking distance. III. Many driver assistance functions can be implemented using X-Boost, and can be performed with greater precision than when implemented by the ESP unit. IV. Regenerative control is easier, quieter, and more accurate when controlled via the DV than when controlled via the intake and exhaust valves and pump of the ESP unit.

[0044] Thus, pedal malfunction I) can be avoided. This is because the stroke simulator is disconnected, so leaks in the system do not affect the pedal feel. In contrast to the problem-solving means according to the present invention, leaks in the system directly affect the pedal feel, for example in modified forms A and B, so in the worst case, the pedal stroke may be suddenly extended, the driver may not be able to control the change, and this may lead to an accident.

[0045] Individual pressure adjustment of the axles and wheel brakes (II) is made possible by the problem-solving means of the present invention. This is because, in the event of a malfunction of the ESP motor, the electric motor of the X-Boost pressure supply unit DV takes over the pressure adjustment, and the pressure adjustment does not affect the pedal. This means that there is considerably more freedom for controlling each axle or wheel than the problem-solving means of a follow-up booster (modifications A and B). For this reason, the pressure control of the present invention through piston stroke and motor current and pressure gradient adjustment (DE10 2005 055751 by the present applicant) (DE10 2005 018649 by the present applicant) is used for high-precision pressure control that cannot be achieved by pulse width modulation (PWM) control of the valve of the ESP unit (these patents are incorporated herein by reference).

[0046] System isolation (system pedals) is also very important for the implementation of III) driver assistance functions, as will be explained in more detail below.

[0047] Regenerative braking (IV) is becoming increasingly important due to the rise of hybrid vehicles and the proliferation of electric vehicles. Brake pressure varies depending on the possible generator braking effect and the total braking effect required by the driver. This is called brake pressure blending. Brake pressure blending can include all-wheel brakes (four-wheel blending), one vehicle axle (two-wheel blending), or individual single-wheel brakes. Brake pressure blending requires appropriate brake pressure control and valve control, which will be explained in detail in the drawings.

[0048] The regenerative control (IV) by the problem-solving means of the present invention is exclusively implemented by controlling the piston stroke of the pressure supply unit DV in the simplest problem-solving means (four-wheel blending). The corresponding brake pressure is set by adjusting the piston so that the sum of the hydraulic brake force and the brake effect of the drive motor yields a desired total deceleration force, in accordance with the deceleration effect of the vehicle's generator or the drive motor of an electric vehicle operating in generator mode.

[0049] This is possible in a fully variable manner because the pressure state of the X-Boost pressure supply unit DV does not affect the pedal feel. This has considerable advantages over modifications A and B of the prior art, in particular, which mean that connecting the pedal and the HZ volume unit must empty the storage chamber of the ESP unit in order to reduce deceleration while maintaining the same pedal feel. This prior art requires an intervening object in the ESP and requires very complex control of the discharge valve of the ESP unit. Furthermore, the solution according to the present invention eliminates various ESP variations for different brake circuit distributions (diagonal and parallel / brake circuits for each axle, rear and front drive units). This is because the control is performed exclusively by the piston, regardless of the brake circuit distribution and drive type. In particular, the advantages of X-Boost described below are also brought about by regeneration.

[0050] As will be explained in great detail below, axle-by-axle blending (two-wheel blending or axle-by-axle blending) is far easier to implement.

[0051] A part of the problem-solving means according to the present invention, in particular X-Boost, brings the following advantages to pedal feel compared to the prior art. • Blending does not alter the pedal feel. • There is no change in pedal feel due to changes in the braking system (e.g., changes in brake release clearance, changes in PV characteristic curve).

[0052] In summary, blending with X Boot offers the following advantages: • Generator torque => Precise brake pressure adjustment even when simple point brakes change rapidly. For example, there should be no perceptible noise from the ESP unit's switching valve. Blending across the entire vehicle deceleration range, • Blending software that is far simpler than conventional e-boosters. • Uniform blending for diagonal (X) and axis-parallel (II) brake circuit division. • The braking force distribution can be displayed arbitrarily up to the wheel lock limit. In particular, it is possible to avoid ESP interference for vehicle stabilization on slippery, uneven road surfaces, and interruptions to the regenerative process using complex switching from regenerative braking to fully hydraulic braking and vice versa. Changes in the wheel brakes acting on the non-driven axle (e.g., pressure-volumetric characteristics, or pV characteristics) should not affect the hydraulic brakes. • There are no additional components required to hold the hydraulic fluid (e.g., no "smart actuators"). • Stronger return spring for pedals (RFE P max (Important to) the absence of, and / or, • The changes in the PV characteristic curve of the brake system will be analyzed.

[0053] In a known system, such as Modification A with a follow-up booster, the pedal stroke is determined by volume absorption. To prevent the pedal stroke from becoming excessive during normal operation, it is necessary to adjust the volume of the main cylinder HZ for various vehicle types with various piston diameters. If a system malfunction occurs at the fallback level RFE, this results in a higher pedal force for the same pedal stroke in a brake system with greater volume absorption. According to the requirements of ECE-13H, a vehicle deceleration of at least 0.24-0.3g is required for a maximum pedal force of 500N.

[0054] A part of the problem-solving means according to the present invention, in particular X-Boost, enables higher brake pressure at the fallback level RFE with a foot force of 500N by allowing the use of a smaller auxiliary piston diameter compared to the SK piston. Furthermore, the fluid volume in the brake circuit can be further increased against brake fade by the DV continuing to supply fluid. This increase must be delivered from the SK piston to the floating circuit using a larger SK piston diameter than the auxiliary piston, or by using a longer stroke of the SK piston.

[0055] In one embodiment described in the present applicant's patents DE10 2005 018649 and DE10 2005 055751, the BKV is controlled by applying pressure according to a specific BKV curve to the brake circuit by a piston in a pressure supply unit DV in accordance with the pedal stroke (these patents are incorporated herein by reference). The pressure is measured by an ESP unit and supplied by the pressure supply unit DV through the corresponding piston stroke. If the pressure sensor fails, this pressure signal is unavailable. The pressure sensor malfunction is detected by the pressure supply unit DV through evaluation of the pressure-volumetric characteristic curve (pV characteristic curve). In this case, the corresponding pressure value is not known during the piston stroke.

[0056] In this case, current measurement of the DV motor can be used instead of pressure measurement. Generally, it is also conceivable that only current measurement may be used. Regarding the accuracy of pressure increases and decreases, hysteresis due to the frictional force of the drive unit must be included in the characteristic curve of the pressure supply unit DV (piston stroke and pressure or, alternatively, current), along with a correction value based on the correlation between current and vehicle deceleration, if any.

[0057] This concept has further potential to enhance functionality and error safety through the following: a) Function A small accumulator, also called a mini storage container, connected to brake circuit 1 (BK1), which allows the ESP pump to further increase the pressure inside the wheel brake cylinder during the suction stroke of the pressure supply unit (DV). • Hydraulic pedal force blending at fallback levels. b) Safety • Use of the additional isolation valve (TV1) in brake circuit 1 (BK1) in the event of a malfunction in brake circuit 1 (BK1). • Elimination of the need for a shut-off valve (WA) in the stroke simulator. This also eliminates the potential for errors. • Measures to prevent sensor activation. • A linear level transmitter for brake fluid in the storage container (VB). This transmitter can detect small fluid volume changes in the storage container (VB) and provide early warning if a leak occurs in the brake system. • Additional shut-off valve (36) for the hydraulic connection from the auxiliary piston chamber to the storage container (VB). • Redundant seals, including diagnostic options for the main cylinder (THZ) and pressure supply unit (DV). - Redundancy measures in the return line from the pressure supply unit (DV) to the storage container (VB) in case of failure of the intake valve (28), such as an additional shut-off valve (MV). • A partially redundant control unit (ECU) for reading and processing sensor signals and controlling the FV valve and PD1 valve. • Cooling down the temperature of electronic components and reducing the failure rate of electronic components by dissipating heat from the PCB to the main body, and therefore to the cooler spray walls. • 2x3 phase control of the motor, i.e., redundant windings.

[0058] This also means that it can meet extremely high requirements regarding fail-operational (FO) operations.

[0059] The following lists additional possible and advantageous features for the possible embodiments described above. These features can be added to the embodiments in combination or individually. For example, the piston of the first piston-cylinder unit (main cylinder) can have various diameters. In particular, the auxiliary piston can be made smaller in size to accommodate pedal forces with a low fallback level (RFE). Furthermore, one module of the two-box structure (X-Boost / ESP) can be connected to a 12V battery or 12V voltage source. The other module can be connected to a DC / DC converter, or a 48V vehicle electrical system or another vehicle electrical system with a higher voltage. In particular, the X-Boost is powered by a DC / DC converter or a 48V vehicle electrical system. For added safety, both modules can be redundantly connected to both vehicle electrical systems, especially the 12V battery and DC / DC converter. The transmission device of the pressure supply unit may have an automatic locking trapezoidal spindle that performs an automatic locking operation in the event of a malfunction in the drive unit. The valve (FV) can be controlled by pulse width modulation (PWM) to generate force feedback to the brake pedal (haptic feedback using ABS). • The plug connector for the system is located beneath the storage container and can be oriented inward towards the center of the device to allow the corresponding plug to be pulled out laterally. The second piston-cylinder unit (pressure supply unit DV) can, advantageously, be aligned parallel or perpendicular to the axis of the first piston-cylinder unit (main cylinder). • Replenishment allows for the availability of a larger volume of brake fluid. This is advantageous in heavier vehicles, or when air bubbles are present in the brake fluid, or when vapor bubbles, which may be generated as a result of brake overheating, are present in the brake fluid. Fault tolerance improvements can be achieved through partial redundancy of the ESP and X-Boost control units. • Appropriate braking distance and driving stability in the event of ESP failure can be achieved by introducing separation valves (TV1, TV2) into the brake circuits (BK1, BK2) and by the hydraulic multi-operation of the pressure supply unit DC. Individual regeneration can also be achieved for each brake circuit. Furthermore, replenishment can be provided to brake circuit 2 (BK2).

[0060] Further features and advantages of the present invention will become apparent from the following description of embodiments, examples, and structures of the present invention. [Brief explanation of the drawing]

[0061] Explanation of the diagram [Figure 1] This shows the full X-Boost system with ESP. [Figure 2] This shows the pedal characteristics. [Figure 3] This shows the main components of the system. [Figure 4] This shows an expanded X-Boost. [Figure 4a] This demonstrates the redundancy of valves (FVs) to enhance functional safety. [Figure 5] This document outlines X-Boost, which includes measures to enhance functional safety. [Figure 5a] This shows a pedal stroke sensor that includes measures to enhance functional safety. [Figure 6] This shows a pressure supply unit with additional valves added to enhance functional safety. [Figure 7] This shows a pressure supply section with redundant seals to enhance functional safety. [Modes for carrying out the invention]

[0062] Figure 1 shows a schematic diagram of a brake system having a drive unit, in particular a brake pedal 1, a first piston-cylinder unit THZ that can be driven using the drive unit, a second piston-cylinder unit (hereinafter referred to as X-boost or booster) equipped with an electric drive unit and transmission, and an ABS / ESP unit. An ABS / ESP unit is known that includes a pump P, which is a main component equipped with a motor M, valves HSV1, HSV2, valves USV1, USV2, discharge valves EV and AV assigned to the wheel brakes, and a storage chamber (SpK). This system has been described in many publications and patent applications. This system is already on the market as an e-boost and is mainly used in electric and hybrid vehicles. This is because the brake system is controlled in conjunction with the brake torque of the generator, i.e., regeneration. As is well known, both the e-boost and ESP elements can play a role, in particular, in pedal characteristics. Another area of ​​application is vehicles with autonomous driving. The focus here is on the redundancy of functions such as error safety, pressure supply function, and ABS function. The main difference in the system structure is the new X-Boost concept. This X-Boost consists of a special main cylinder HZ including a stroke simulator WS and a pressure supply unit DV, the pressure supply unit DV is positioned parallel or perpendicular to the main cylinder HZ to achieve a short overall length, as also shown in Figure 3.

[0063] The main cylinder HZ basically consists of an auxiliary piston (HiKo) 16 and an SK piston (floating piston) (12) with a return spring 12a. The auxiliary piston 16 is connected to a plunger 16a, which operates to enter the pressure chamber 12d through a partition wall 14 having a seal. Approximately 50% of the stroke distance of the auxiliary piston (HiKo) 16 is between the end of the plunger and the SK piston. The plunger (16a) has a significantly smaller cross-sectional area (>5 times smaller) than the piston of the first piston-cylinder unit and contributes little to pressure increase and pressure detection in the brake circuit, and transmits this force to the brake pedal, thereby generating tactile feedback to the brake pedal, especially during ABS operation and / or fade phenomena.

[0064] Normally, valve FV is closed when the brake is initiated, and auxiliary piston HiKo acts on the stroke simulator WS. The function and variations of the stroke simulator WS will be described later. Auxiliary piston HiKo has two functions: a function for normal operation and a function for the fallback level in case of a failure of the pressure supply unit DV. In the first case, which is normal operation, the auxiliary piston delivers fluid to the stroke simulator WS with valve FV closed, and the pedal stroke is the input signal to the pressure supply unit DV. In the fallback level in case of a failure of the pressure supply unit DV, the auxiliary piston similarly delivers fluid to the stroke simulator WS when valve FV is closed, but in this case the pedal stroke is the input signal to the ESP booster.

[0065] When the brake pedal 1 is driven together with the pedal plunger 3, redundant pedal stroke sensors 2a / 2b are activated simultaneously. Furthermore, these sensors can be disconnected via an elastic member KWS, as described in the present applicant's patent DE11 2011 103274, which is referenced herein in this regard. The advantage is, on the one hand, that the auxiliary piston (HiKo) 16 is stopped, and on the other hand, that the stroke difference between the sensors when the auxiliary piston (HiKo) 16 is stopped provides a control signal for the auxiliary brake. The elastic member can also be part of the spring characteristics of the WS stroke simulator. The auxiliary piston (HiKo) 16 has a standard breather hole of a THZ piston connected to a storage container VB. It is well known that if the main seal fails, the brake circuit will fail. This can be avoided by using a check valve RV and a throttle used for discharge in the connection line to VB. The throttle is positioned for small flow rates, so even if the seals fail and can still be diagnosed, the pedal characteristics do not change significantly (3 mm pedal stroke in 10 seconds). The same configuration can also be used with the floating piston (SK) 12 (not shown), which makes failure of both seals non-fatal. Alternatively, a solenoid valve that is normally open can be used in the feedback line. The solenoid valve closes after pedal drive or diagnosis. This applies to both pistons of the HZ (auxiliary piston HiKo and the second piston SK).

[0066] The stroke simulator WS can be designed in various ways. The illustrated structure corresponds to prior art described in various patent applications, consisting of a combination of a WS piston and spring. This combination provides pedal stroke characteristics as a function of the pedal stroke. The valve RV provides rapid pressure reduction P from the stroke simulator WS when the pedal is released very suddenly. ab Used for the following: Throttle D is a desired adjusted pressure increase P with corresponding pedal characteristics. aufIt is used for this purpose. Furthermore, the stroke simulator WS can be stopped by valve WA. This is essential for non-redundant systems at fallback level (RFE). The intake volume of the stroke simulator WS does not affect the output volume of the auxiliary piston HiKo to the brake circuit BK1 and pressure chamber 12d. In this system (Figure 1), the ESP functions redundantly in the event of a failure of the X boost. The ESP pump draws volume from the storage container via the main cylinder THZ and pressure supply unit DV. Therefore, valve WA can be eliminated. The auxiliary piston (HiKo) 16 with pedal plunger 16a is moved to its initial position by pedal return spring 18 after brake operation.

[0067] A pressure supply unit or DV is required for the BKV function. The pressure supply unit consists of an EC motor 8 that moves the piston 10 via a spindle 7 and nut, and delivers pressure medium to the brake circuit BK1 and pressure chamber 12d. The fluid volume is obtained from BKV control, which controls the pressure from the pedal stroke 2a / 2b by BKV characteristic curve measured by a pressure transducer DG in the ESP. Alternatively, instead of pressure, motor current measured via a shunt can be used. To improve the accuracy of pressure control by current measurement, pressure control by current measurement is performed on the characteristic map P auf and P ab This requires recording the pressure loss and, selectively, further improving it with corrective factors such as comparison with the vehicle's deceleration. This is especially important when the spindle drive is not a ball screw drive KGT, but rather a trapezoidal spindle with, for example, a plastic nut.

[0068] The piston 10, like the main cylinder THZ, has a breather hole 27 in the starting position. The volume can be drawn in through a temperature-independent sleeve or an intake valve (SV) 28 that requires only low pressure reduction to open.

[0069] When a trapezoidal spindle is used, the piston remains in a position where the motor drive unit cannot move due to the piston's automatic locking mechanism.

[0070] The sizing of the pressure supply unit DV can be adjusted such that the full stroke of the DV piston corresponds to the volume consumption of the brake circuit BK2 or the stroke of the SK piston 2. The SK piston can be designed with a larger diameter and further a larger stroke as the volume intake is larger. On the other hand, the pressure supply unit DV can be designed accordingly. Or, by replenishing through the SV intake valve for the piston return stroke, the insufficient liquid volume can be made available and the volume (piston and stroke) can be designed to be smaller. For this purpose, a normally closed solenoid valve PD1 not shown in FIG. 1 (see FIG. 4) is required. When the pressure reduction P ab occurs, in order to compensate for the full liquid volume, the piston must move to its initial position with the breather hole open. The intake valve 28 and the breather hole 27 are connected to the return line towards VB. All components of the pressure supply unit DV are incorporated within one housing 25.

[0071] [[ID=⑧]] The pressure increase P auf and the pressure reduction P ab of the brake circuit BK1 and the brake circuit BK2 are achieved through the BKV control and the pedal stroke sensor, and the piston of DV moves accordingly. Normally, the X boost pumps the volume to the brake circuit BK up to the maximum cut-off limit of 80 to l20 bar. When a higher brake pressure is required for the fade phenomenon, the X boost pumps it to the ESP pump at 80 to l20 bar, which results in a higher pressure level. Previously, the ESP pump had to be sized for the delivery volume corresponding to a maximum pressure of, for example, 200 bar by the ASR operation. With a suitable pump structure, such as a two-circuit gear pump or an independent eccentric for the pump piston, and further, a stepped piston, etc., the ESP pump only has to cope with the pressure difference between the brake circuit pressure and the X boost pressure. For example, P Bremskreis(=200 bar) - X boost (=80~120 bar) = 80~120 bar, therefore only 80~120 bar, not 200 bar, is required for the ESP pump structure, and thus a correspondingly smaller ESP motor is sufficient. Furthermore, in this pump structure, for rapid deceleration, it is possible to place the E boost and ESP pumps in parallel from an already low pressure range, e.g., from 20 bar. Therefore, this is P auf This offers the possibility of making (TTL) faster and X-boost motors smaller.

[0072] If the pressure supply unit DV fails during the braking process, the DV piston is pushed back by the pressure in the brake circuit BK1, so the brake pressure can be completely reduced. Such pressure reduction is not possible when an automatic locking gear is used for the DV piston (trapezoidal spindle with plastic nut). In this case, a normally closed solenoid valve AV is provided in the brake circuit BK1, along with a connection to a storage container (not shown), or at the connection from the breather hole of Hiko to the storage container VB.

[0073] In the rare event of a malfunction in either the X-Boost or ESP electronic control or adjustment unit (ECU), at fallback level RFE, the auxiliary piston (HiKo) 16 sends a volume through the open valve FV to the brake circuit BK1 and the main cylinder HZ on the rear side of the SK piston, increasing the brake pressure. The brake pressure in the main cylinder HZ moves the SK piston, increasing the pressure in the brake circuit BK2. A normally closed solenoid valve PD1 is provided to prevent this volume from leaking through the open breather hole of DV (not shown in Figure 1; see Figure 1a).

[0074] Function in case of brake circuit (BK) malfunction Brake circuit malfunctions are detected by the pressure supply unit DV as part of the diagnostic cycle, by comparing the pV characteristic curves of the brake system stored in a characteristic map at specific intervals.

[0075] For example, if the piston stroke / volume is greater than the standard value, there is correspondingly air present or leaking in the brake circuit (BK). This can be identified by the pV characteristic curve. If a leak occurs, it can be identified by sequentially closing the four valves EV, provided that the leak is located outside the unit, for example, in the wheel cylinder. For example, if the leak is in brake circuit BK1, valve EV in brake circuit BK1 is closed. Then, the pressure supply unit DV acts on brake circuit BK2 via the SK piston (similar to the description of the diagnostic logic in patent applications DE10 2015 106 089.2 and DE10 2016 112 971.2 cited here). If this does not work properly, the pressure supply unit DV is not functioning, and the brake booster BKV is also not functioning. In this case, the ESP pump functions as the brake booster BKV in brake circuit BK2.

[0076] The SK piston (12) acts as an important safety gate along with the separation of brake circuits BK1 and BK2, so a malfunction in brake circuit BK2 will not cause a malfunction in the pressure supply unit DV.

[0077] In both cases, the pedal characteristics are the same, and the pedal will not cease to function.

[0078] ABS function in case of pump / motor malfunction via ESP ABS pressure reduction signal P ab If this occurs, DV control modifies the brake pressure to prevent the wheel from locking. Corresponding pressure reduction P in both brake circuits. ab This is necessary to prevent one of the two brake circuits from locking up. However, this does not mean optimal braking performance, but this can be improved.

[0079] For example, when a wheel locks, one of the brake circuits applies a corresponding pressure reduction P ab When this is done, the other brake circuit reduces pressure by closing valve USV Pab This cannot be achieved. This can be optimized by adjusting the individual wheel adjustments by adjusting the valve EV, without the need for a parallel check valve RV, as described in the patent application DE11 2009 004636 (E112) cited herein.

[0080] Figure 2 shows the pedal stroke S. p This shows the pedal characteristics over a range. In region A, the force increase in curve 1 is relatively constant up to a brake pressure of about 30 bar, which corresponds to about 85% of all braking action. This process can be carried out via the pedal return spring. Then, a more progressive section B acts up to the stopping limit, followed by a higher pressure range, such as in the case of brake fade. In this case, the driver also feels that there has been a change in the braking system.

[0081] Curve 1 corresponds to X-boost with stroke simulator WS. In the absence of WS, i.e., in the case of a follow-up booster, the pedal stroke becomes curve 2, which changes due to venting or fading. Therefore, in the event of a brake circuit (BK) malfunction, there is a further diffusion to the more extreme 2a (not shown). In the case of a conventional e-boost, the BKV switches from the e-boost to the ESP booster at x. This changes the pedal characteristics. Without affecting the BKV control, with the same pressure and pedal force, the pedal with the main cylinder (HZ) piston sends an additional volume to the ESP pump until the pressure in the wheel cylinder reaches a target value. That volume overflows valve USV and returns to the main cylinder HZ.

[0082] The larger pedal stroke and altered pedal characteristics are achieved by reducing the amplification factor of the X-Boost, which results in a more clearly defined scatter band. Furthermore, valves HSV1 and HSV2 can be adjusted.

[0083] Here, the X-Boost according to the present invention, which has a stroke simulator WS, behaves like curve A, where the corresponding progressive force increases in accordance with the pedal stroke.

[0084] ABS pedal feedback In the case of ABS functionality, the preload supplied by the DV is constantly changing. This preload acts on plunger 16a and can be felt as a small force change acting on the connected pedal plunger 3. This is a feature requested by many brake specialists. This preload can be changed by intermittently increasing the intake pressure for a short period of time at the start of ABS or during deceleration.

[0085] If the reaction is more pronounced, the FV valve opens, and the DV control pressure acts directly on the auxiliary piston HiKo.

[0086] Regeneration using Stroke Simulator WS Pedal characteristics are determined by the stroke simulator WS. Here, the brake management using the generator determines the ratio of generator brake torque (electric brake torque) to brake pressure (hydraulic brake torque) for the required vehicle deceleration. Both amounts can be arbitrarily changed during deceleration. Regeneration can be applied in the following ways: a. the same brake pressure for all four wheel cylinders, b. brake pressure per axle at the vehicle axle, or c. brake pressure per wheel at all four wheel cylinders. Here, special control methods are required for the pressure supply unit DV, and in cases b. and c., for the corresponding valve structure or the corresponding valve and pump control of the ESP unit.

[0087] a. The calculation of brake pressure during regeneration is preferably based on wheel force. The total required brake force acting on the wheel (target brake force) is determined from the pedal stroke. When the target brake force can be applied electrically, the hydraulic brake force is 0 N (brake pressure in the cylinder is 0 bar). When the target brake force exceeds the maximum possible electric brake force, the difference between the target brake force and the electric brake force is the hydraulic target brake force. The hydraulic target brake force is realized by the pressure supply unit DV through pressure generation in the wheel cylinder. For this purpose, the target brake pressure is calculated using the individual Cp values ​​of the wheel brake, where the Cp value of the wheel brake represents the ratio of brake force to brake pressure. The target pressure is generated by the corresponding movement of the DV piston. The pressure sensor of the ESP is used for feedback of piston movement. In this way, the pressure supply unit DV can set the target pressure both when the pressure is increasing and when the pressure is decreasing. Due to the high-precision position control of the DV piston, the pressure setting is very accurate. Pressure control by DV is P auf and P ab Because no valves need to operate, it is extremely quiet. The operation of valves and pumps, which are the source of noise in the ESP unit, is not required. Furthermore, this regenerative control can be used uniformly for front-wheel, rear-wheel, and all-wheel-drive vehicles, as well as for X and II brake circuit splits. Pedal characteristics remain unchanged.

[0088] In case b., where the brake pressure for each axle at the vehicle axle is used, the ESP valves and pump motor may also need to be controlled. If the target braking force exceeds the maximum possible electric braking force, the difference between the target braking force and the electric braking force is the hydraulic target braking force. This hydraulic target braking force is initially applied only to the drive axle by the pressure supply unit. The EV on the non-drive axle is closed. The non-drive axle must also be braked hydraulically (for vehicle stabilization during braking) from a certain vehicle deceleration (e.g., from 0.2g). The hydraulic target braking force must then be applied together to both vehicle axles. The brake pressure on the non-drive axle is less than or equal to the brake pressure on the drive axle. The pressure on the drive axle is increased by the DV when the EV opens. The pressure on the non-drive axle is adjusted by appropriate PWM control of the EV on the non-drive axle. For example, if the hydraulic target braking force must be reduced because the driver releases the brake pedal or the generator time is extended, the brake pressure on both axles is reduced. This is achieved by appropriate control of the pressure supply unit DV in the drive axle where valve EV is open. Pressure reduction in the non-drive axle is achieved by the opening (potentially clock-controlled) of valve AV, in conjunction with control of the ESP pump and pulse width modulation (PWM) control of the valve (EV) in the non-drive axle. The PWM control of valve EV is intended to prevent an extreme drop in pressure at the rear axle. As a result, if the pressure at the rear axle drops to 0 bar, a further reduction in the hydraulic target braking force occurs exclusively via the pressure supply unit DV, the valve at the drive axle opens, and valves EV and AV at the drive axle close. The AV at the drive axle remains closed throughout these processes. Therefore, valve and pump noise occurs only in the non-drive axle when a certain vehicle deceleration (e.g., 0.2g) is exceeded.

[0089] In case c., where brake pressure is used for each wheel in all four cylinders, the ESP valves and pump motors may also need to be controlled. The control of the pressure supply unit DV, valves, and ESP pump is carried out in the same manner as in the situation described in b.

[0090] Driver assistance features There are many driver assistance features that require automatic braking intervention, such as the following: • Adaptive Cruise Control (ACC) sets the desired vehicle deceleration through active brake interference. • AWB (Automatic Warning Brake) uses a brake impulse to wake up a driver who has fallen asleep. • The extremely low brake pressure of the wheel cylinders wipes a thin film of water from the brake disc during rainfall, thereby providing immediate maximum braking effect during the next braking (BDW - Brake Disc Wiping).

[0091] In these assistance functions, the DV pressure supply unit can generate the necessary brake pressure within the wheel cylinder. The target brake pressure is specified by various driver assistance systems. In the case of ACC, the target brake pressure is variable and determined by the required vehicle deceleration. In contrast, in the case of BDW, the target pressure has a small value (e.g., 1-3 bar). Similar to regenerative braking, the brake pressure is generated by the corresponding movement of the DV piston. In this case, the ESP pressure sensor is used for feedback of piston movement. Similar to regenerative braking, the brake pressure setting is extremely precise due to the precise position control of the DV piston. Pressure control by the DV pressure supply unit is also very quiet in driver assistance systems.

[0092] The graphical description in Figure 2, in particular, illustrates the decisive advantages of the present invention, in addition to the overall length.

[0093] Figure 3 shows the following main components of X-Boost in spatial representation. • Pedal plunger 3 • Mounting flange BF on the front wall • First piston-cylinder unit or main cylinder HZ including pedal connection section • Advantageously, the motor 8 includes a housing pressure supply unit l(DV)25 positioned parallel to the main cylinder (it can also be aligned perpendicular to the axle of the HZ). • Hydraulic control and adjustment unit (HCU) • Electronic control and adjustment unit (ECU) Storage container VB The plug connector ST is located below the storage container VB and above HZ and HCU, and is oriented inward toward the center of the unit to allow the corresponding connector to be pulled out laterally.

[0094] Figure 4 shows additions to Figures 1 and 1a, and is based on this description. The additions are a storage container (VB) and a control unit (ECU) connected to the sensors, solenoid valves, and motor electrical connections e. The control unit (ECU) has a partially redundant sub-control unit (ECU2) for operating safety-related components, such as FV valves, using an optional standalone vehicle electrical system connection. For example, this sub-control unit (ECU2), which uses signals from pedal stroke sensors (2a, 2b), can preferably be integrated into an existing ASIC with redundant power supplies.

[0095] At the connection point to the storage container (VB), the sensor element (33) is incorporated into the printed circuit board (PCB), and a floating body (34) and a target (T) are provided inside the storage container (VB). This enables analog evaluation of the height of the brake fluid inside the storage container (VB) and assists in system diagnosis. For example, if the pressure increases due to the pressure supply unit (DV), then decreases, and then the height decreases, a leak is occurring in the system.

[0096] The printed circuit board (PCB) is preferably mounted on an aluminum plate or aluminum carrier (37) that has good thermal conductivity to the body (38) and the spray wall (39). At peak load, when the maximum temperature of the subsequent casing (39a) is 30°C due to cooling, the outside temperature of the control unit (ECU) may reach 120°C and the spray wall (39) may reach 60°C. The aluminum plate allows for a considerable temperature reduction to be achieved in the MOSFET (33a). The MOSFET (33a) tabs are transmitted to the aluminum plate (37) via so-called via holes (V). As is well known, the failure rate of electronic components has a strong temperature dependence, particularly according to Arrhenius's law.

[0097] The EC motor (8) has a redundant connection section e red Through this, redundant control can be achieved by 2x3 phase control. The process is well known. Typically, the EC motor (8) requires an angle encoder as a motor sensor (40).

[0098] Here, the pressure supply unit DV has an additional solenoid valve PD1 that is normally closed. This solenoid valve is necessary when the DV piston is pressed back by the fallback level and a corresponding amount of fluid is lost in the brake circuits BK1 and BK2. This can be compensated for by a large-volume auxiliary piston HiKo, but this would adversely affect the pedal characteristics. When the DV piston reaches its initial position, the breather hole opens and brake fluid flows into the reservoir. At the fallback level RFE, valve PD1 is closed. Valve PD1 can be opened again in the event of ESP interference or ESP boost.

[0099] As already explained in Figure 1, in order to deliver a certain amount of brake fluid to the brake circuit 1 (BK1), the volume is drawn in from the storage container (VB) via the suction valve (28) by pulling back the DV piston (10). For this purpose, valve PD1 is closed and the DV piston (10) retracts. The DV piston (10) draws brake fluid from the storage container (VB) via the suction valve (28) and the hydraulic connection (R). When the re-delivery volume is drawn into the DV chamber (10), valve PD1 opens and the DV piston (10) moves forward. The DV piston (10) pushes the re-delivery volume into the brake circuit 1 (BK1). When the ESP return pump (P, Figure 1) actively increases the pressure in the wheel brake cylinder during the suction phase of the pressure supply unit (DV), a negative pressure is generated in the brake circuit 1 (BK1). In this case, volume delivery by the ESP return pump (P, Figure 1) is delayed, and in some cases, the ESP return pump (P, Figure 1) in the brake circuit 1 (BK1) draws in replenishment volume through the seal D4, the replenishment hole (47) of the main cylinder (THZ), and the hydraulic connection (48) from the storage container (VB). The SK piston (12) is pushed back by the SK piston spring (12a). In this case, the position of the SK piston no longer corresponds to the pressure in the wheel brake cylinder. This can adversely affect the pressure reduction when the driver releases the brake pedal (1). A mini storage container (35) in the brake circuit 1 (BK1) may be provided to prevent this stagnation of volume delivery or this backward movement of the SK piston from occurring. During the suction phase of the pressure supply unit (DV), the mini storage container (35) supplies volume to the ESP return pump (P, Figure 1). The required capacity of the mini storage container (35) depends on the duration of the suction phase and the volume delivery capacity of the ESP return pump (P, Figure 1).

[0100] To enhance the usefulness of X-Boost and to check the function of the stroke simulator (WS), a shut-off valve (36) can be provided at the hydraulic connection (44) between the auxiliary piston's supply hole (42) and the storage container (VB). For example, if there is a leak in the auxiliary piston seal (D2), the shut-off valve (36) can be closed, thus avoiding a malfunction of the stroke simulator (WS).

[0101] The shut-off valve (36) can also be used to check various diagnostic functions. For this purpose, valve PD1 is opened and shut-off valve (36) is closed. When the pressure supply unit (DV) is activated, pressure is applied to the brake circuit 1 (BK1), and the pressure can be measured, for example, using the ESP's pressure sensor (DG). At this time, for example, the closing function of the stroke simulator's shut-off valve (WA) can be checked. If valve FV is opened when the DV piston (10) is in a certain position, the pressure in the brake circuit 1 will drop only slightly if the stroke simulator's shut-off valve (WA) is functioning correctly. Then, when the stroke simulator's shut-off valve (WA) is opened, the pressure in the brake circuit 1 (BK1) will drop considerably more if the stroke simulator's shut-off valve (WA) is intact. If there is a leak in the stroke simulator's shut-off valve (WA), the pressure in the brake circuit 1 (BK1) will drop considerably more, even if the stroke simulator's shut-off valve (WA) has not yet been activated, and will not drop any further when the stroke simulator's shut-off valve (WA) is opened. If there is a leak in the piston seal D6 of the stroke simulator piston (49), the pressure in brake circuit 1 (BK1) will continue to drop further after the stroke simulator shut-off valve (WA) opens.

[0102] If the stroke simulator (WS) fails, for example, even if there is a leak in the valve FV, the valve FV will normally open. When the brake pedal (1) is driven, the driver pushes the volume from the auxiliary piston chamber (43) to the ESP return pump (P, Figure 1) in the brake circuit 1 (BK1). The ESP can then apply pressure to the cylinder by the ESP's active braking function, depending on the position of the pedal (1). The pedal stroke is significantly longer to achieve a certain pressure in the wheel brake cylinder than using the intact X-boost. This can surprise the driver and lead to unpredictable behavior. To avoid this, a pressure supply unit (DV) can be used to generate a hydraulic pedal reset force, so that the pedal force becomes similar to the pedal force with the intact X-boost function. For this purpose, the pressure in the brake circuit 1 (BK1), and therefore the pressure in the auxiliary piston chamber (43), is also adjusted by the pressure supply unit (DV) to reproduce the standard pedal force / pedal stroke characteristics of the stroke simulator as intended by the vehicle manufacturer. If this reproduction is successful, the driver will not be surprised by longer pedal strokes, and the driver's actions will be more predictable. In this example, the stroke simulator (WS) functions normally, but the increase in brake pressure in brake circuit 1 (BK1) by the pressure supply unit (DV) can occur with shorter pedal strokes only after the auxiliary piston sniff hole (45) is closed, or only if the shut-off valve (36) is used. However, when using the active braking function of the ESP, the pressure in the wheel brake cylinder may already be high before the auxiliary piston breather hole (45) is closed.

[0103] Figure 4a illustrates measures to enhance the functional safety of X-Boost. The valve FV can be extended with respect to redundancy by FVred, preferably using a controlled flow from the sealing ball to the valve seat.

[0104] Figure 5 shows the entire X-Boost system with ESP. The X-Boost, valve, and pressure supply unit DV with THZ are the same as those in Figure 4, except for the improved connection of the intake valve (28), which is also shown in Figure 7. Figure 5 shows the redundant seal (D2.1) and replenishment hole (50) for the auxiliary piston (16), along with the throttled discharge section (Dr2.1) to the storage container (VB). The throttle Dr2.1 is designed to be narrow so that, in the event of a leak in the seal (D2), only a small leakage flow can reach the storage container (VB) from the auxiliary piston chamber (43) through the replenishment hole (50), but this simply results in a slow, short, non-interfering extension of the stroke of the brake pedal (1) during limited braking time. This leakage flow is detected by pedal stroke sensors (2a, 2b) during validation checks, but is also detected in the system diagnostics described in E144.

[0105] As redundancy for seal D4, an additional seal D4.1 is also shown. If this seal D4.1 fails, the brake circuit BK1 and the pressure supply unit DV also fail. In this case, the ESP unit performs the work of the pressure supply unit, i.e., increasing the pressure. This can be avoided by the combination of seals D4, D4.1 and the replenishment hole 52, and a throttle Dr4.1 is provided at the connection of the replenishment hole 52 to the storage container, as well as an auxiliary piston (HiKo) 16. Failure of this seal 4.1, through which a small leakage flow passes through the throttle D44.1, does not result in failure of the brake circuit BK1 or the pressure supply unit DV. Furthermore, diagnosis of seal D4.1 is preferably possible using this configuration. Alternatively, a normally open valve TV can be provided at the connection to the storage container. This valve can be closed if a leak occurs in seal D4 or seal D5.

[0106] For seal D3, a redundant seal D3.1 can also be used together with the replenishment hole 51 and throttle Dr3.1. Furthermore, the stroke simulator seal D6 can also be redundantly equipped with seal D6.1, replenishment hole 53, and throttle Dr6.1. This means that all functionally important seals are redundant, and leaks can be detected during braking and diagnostics. This achieves a high level of safety against fail operation (FO). This seal configuration can also be used in conjunction with a single-circuit main cylinder (THZ) that has a pressure rod piston and does not have a floating circuit.

[0107] If there is a leak in brake circuit 1 (BK1) between the ESP and the wheel cylinder of brake circuit 1 (BK1), both brake circuit 1 (BK1) and the X-Boost pressure supply unit (DV) will cease to function. The leak also poses a risk of brake fluid being lost to the surrounding environment. As a countermeasure, the ESP can close both intake valves EV of brake circuit 1 (BK1). If a malfunction is detected by X-Boost but X-Boost does not access these valves (EV), X-Boost must switch to the ESP's active braking function. In this case, the ESP adjusts the pressure in the wheel brake cylinder of brake circuit 2 (BK2). If the pressure in the wheel brake cylinder of brake circuit 1 (BK1) is not adjusted, the ESP must constantly supply volume to brake circuit 1 (BK1). If the ESP does not detect a leak in brake circuit 1 (BK1), brake fluid will be constantly lost. To address this situation, a separation valve TV1 is provided in the brake circuit 1 (BK1) between the pressure chamber (12d) of the main cylinder (THZ) and the ESP. When X-Boost detects a leak in the brake circuit 1 (BK1), valve TV1 is closed. The pressure supply unit (DV) can then supply pressure to the pressure chamber (12d) of the main cylinder (THZ), and consequently to the brake circuit 2 (BK2), without losing brake fluid.

[0108] Furthermore, in the event of an ESP malfunction, valve TV1 can be used to provide optimized braking distance on slippery roads. For legal reasons, when braking on slippery roads, the front axle wheels must lock before the rear axle wheels. Because of this, the rear axle wheels will not brake sufficiently when the vehicle is slowing down even slightly. In the case of X-Boost, valve TV1 can be closed when the front axle wheels of brake circuit 1 (BK1) of the II brake circuit division show a tendency to lock. In this case, the brake pressure in the rear axle wheel brake cylinder of brake circuit 2 (BK2) can be further increased using the X-Boost pressure supply unit (DV) until the rear axle wheels also show a tendency to lock. This means that almost maximum deceleration can be achieved on slippery surfaces. Naturally, after increasing the pressure in the rear axle wheel brake cylinder, it is also possible to further increase the pressure in the front axle wheel brake cylinder by briefly opening valve TV1. In the case of X-brake circuit splitting, valve TV1 can be closed when the front wheel of brake circuit 1 (BK1) shows a tendency to lock. After valve TV1 closes, the pressure in brake circuit 2 (BK2) can be further increased until the rear wheel of brake circuit 2 (BK2) shows a tendency to lock. Since the pressure in brake circuit 1 (BK1) is low, the vehicle remains sufficiently stable, while the high pressure in brake circuit 2 (BK2) results in a shorter braking distance.

[0109] In the supply line BK2 from THZ to ESP, the separator valve TV2 is used in brake circuit 2 (BK2). Similar to separator valve TV1, the valve seat output is connected to the ESP, so a hydraulic connection is important. These two separator valves, TV1 and TV2, can be used to perform the following functions: 1. Replenishment, step 2. As already explained with respect to Figure 4, the fluid volume in brake circuit 1 (BK1), and therefore the reachable pressure levels in brake circuit 1 (BK1) and brake circuit 2 (BK2), is suppressed by replenishment when the SK piston (12) of the main cylinder (THZ) stops. In this case, further pressure increases are possible only in brake circuit 1 (BK1). The stopping of the SK piston (12) is identifiable because the pressure in brake circuit 1 (BK1) increases twice as fast as the volume in brake circuit 1 (BK1) increases. When the SK piston stops, the separation valves TV1 and TV2 close accordingly, and the piston (10) of the pressure supply unit (DV) retracts. The pressure in brake circuit 1 (BK1) drops very rapidly. Under the influence of the return spring (12a) of the SK piston (12), the SK piston (12) may retract to its initial position, moving the volume from the main chamber (12d) of the main cylinder (THZ) through the brake circuit 1 (BK1) line and through valve PD1 to the chamber of the pressure supply unit (DV). Simultaneously, the SK piston (12) uses the hydraulic connection 48 of the main cylinder (THZ) leading to the storage container (VB) to draw the volume from the storage container (VB) through the seal D5 of the SK piston (12) and through hole 47 into the chamber in front of the SK piston (12) of the main cylinder. Due to the modified connection of the intake valve (28), the intake valve is not effective while the piston (10) of the pressure supply unit (DV) is in the front region, and when the piston (10) of the pressure supply unit (DV) retracts, the volume is not drawn from the storage container through the intake valve (28) and connection R (see also the explanation for Figure 7). At the end of this intake process, the separation valves TV1 and TV2 are opened again. With the next forward stroke of the piston (10) of the pressure supply unit (DV), the SK piston (12) of the main cylinder (THZ) moves forward again, and the pressure in both brake circuit 1 (BK1) and brake circuit 2 (BK2) can increase further. The pressure supply unit (DV) is preferably controlled using the pressure reference value of the X boost. 2. Separation valves TV1 and TV2 can also be incorporated into the ESP as a replacement for the switching valves (US1, USV2), provided that the valve outlet is hydraulically connected to the wheel cylinder via the intake valve (EV) as described above. This leads to cost and weight savings. 3. As already explained, in the event of an ESP failure, the ABS function of brake circuit 1 (BK1) can be performed using the separator valve TV1 and the pressure supply unit (DV). Together with the separator valve TV2, the ABS function can be performed in both brake circuit 1 (BK1) and brake circuit 2 (BK2). When each wheel of the brake circuit is individually ABS controlled, four intake valves (EV) can be used in conjunction with it. This is a significant advantage, especially with respect to the diagonal division of the brake circuit. The control process is not shown here. Pressure control is always performed by the pressure supply unit (DV).

[0110] A partially redundant control unit (partially redundant ESP-ECU) can be used in the ESP to control the intake valve (EV) and the isolation valves (TV1, TV2), replacing the main control unit of the ESP (ESP-ECU). Preferably, its functions include processing sensor signals from the speed sensor and the yaw speed sensor for the ABS emergency function. However, this partially redundant control unit (partially redundant ESP-ECU) can also be connected to the X-Boost (X-Boost ECU) control unit.

[0111] All control units (ECUs), partially redundant control units, and partially redundant control units (partially redundant ECUs) have redundant connections to the vehicle electrical system (S1), including the power supply and bus system (Sn), in addition to the connection to the vehicle electrical system (S1). Partially redundant connections to the ESP are indicated by the symbol of a "circle with a cross".

[0112] As already mentioned in the explanation of Figure 4, the X-Boost (X-Boost ECU) control unit may also have a partially redundant part (partially redundant X-Boost ECU). This partially redundant part preferably supplies power to the following components indicated by the "circle": namely, the pedal stroke sensor (2a, 2b), the isolation valve FV, and the DV valve PD1. This partially redundant control unit (partially redundant X-Boost ECU) may also perform the work of a partially redundant ESP control unit (partially redundant ESP-ECU). This is because the emergency function of ABS must also be provided to the partially redundant X-Boost control unit (partially redundant X-Boost ECU).

[0113] Each ECU or partially redundant ECU has redundant connections to the vehicle's electrical system.

[0114] Figure 5a illustrates a solution to enhance safety using an example of a pedal stroke sensor (2a). In the extremely rare case where sensor 2a does not move when the brake pedal (1) is driven, pedal movement becomes impossible and the brakes fail to function. A preload spring (41a) is provided inside the sensor (2a), and the sensor plunger (2a1) can move against the preload of the spring (41a) when the movement of sensor (2a) is prevented. Errors can be determined by validating the signals of two pedal stroke sensors (2a, 2b) with elastic members (KWS). Two redundant return springs 18a, 18b that operate when the brake pedal (1) is driven replace the center return spring 18. When the brake pedal (1) is released, if sensor 2a does not move, it is impossible to completely release the brake pedal (1). As a result, the vehicle continues to be braked against the driver's will. To address this situation, a notch (2a11) is provided on the plunger 2a1, and the dimensions of this notch are determined so that the plunger breaks at the notch (2a11) due to the influence of the plunger force. Naturally, this solution can also be used together with the pedal stroke sensor 2b to enhance the safety of the pedal stroke sensor 2a.

[0115] Figures 6 and 7 show solutions to the problem of a malfunction in the suction valve (28) of the pressure supply unit (DV). A malfunction in the suction valve (28), such as leakage, impairs the function of the pressure supply unit (DV). This is because the volume in the operating chamber (11) of the pressure supply unit returns to the storage container (VB) via the suction valve (28) and the return line (R), rather than entering the brake circuit 1 (BK1) via valve PD1.

[0116] Problem-solving method 1 (Figure 6): A solenoid valve (MV) is used as a shut-off valve in the return line (R) between the intake valve (28) and the storage container (VB). The solenoid valve (MV) closes when a leak is detected in the intake valve (28). The solenoid valve (MV) can be opened to draw brake fluid into the DV chamber in the pressure supply unit (DV).

[0117] Problem-solving means 2 (Figure 7): An additional suction hole (46) and an additional seal (D9) on the DV piston (10) are provided at an intermediate position on the DV piston (10) of the pressure supply unit (DV). The additional suction hole (46) connects the DV operating chamber (11) to the storage container (VB) via a suction valve (28) and a return line (R). As a result, when the pressure increases while the seal (D9) is intact, the suction valve (28) cannot function after the DV piston (10) has passed the intermediate position. In this case, a malfunction of the suction valve (28) does not affect the pressure increasing function of the pressure supply unit (DV) in any way. When the DV piston (10) retracts to its intermediate position, it draws in only the volume from the storage container (VB) through the sleeve (D9), suction hole (46), suction valve (28), and return line (R), but with two pressure losses (seal D9 and suction valve 28). Only before the DV piston (10) reaches the intermediate position can the suction valve (28) function again. Since the suction function only works during the next transfer, no further disadvantages can be found. Further transfers are necessary when additional volume is required for high pressure levels or to compensate for insufficient ventilation.

[0118] Similar to the main cylinder (THZ) seal D4, a redundant seal D8.1 can be used for the piston seal D8 together with the breather hole (53) and throttle Dr8.1. In this way, the pressure supply unit (DV) also satisfies the "fail-operational" (FO) requirements.

[0119] From the above explanation, the measures described in detail will lead to further modifications of the brake system according to the present invention, and these modifications will also fall within the scope of the claims of the present invention. [Explanation of symbols]

[0120] List of reference numbers 1. Brake pedal 2a Master pedal stroke sensor 2a1 Plunger of pedal stroke sensor 2a 2a11 Pedal stroke sensor 2a plunger 2a1 notch 2b Slave pedal stroke sensor 2b1 Pedal stroke sensor plunger 2b 3 Pedal plunger 7. Spindle (KGT), trapezoidal spindle 8 EC motor 10 Piston (DV) 11 DV pressure chamber or working chamber 12 SK Piston 12a Return spring SK piston 12d Pressure chamber or operating chamber (rear) of floating piston SK 14 Partition Wall 16 Auxiliary piston 16a Plunger 18 Pedal return spring 18a Pedal return spring for pedal stroke sensor 2a 18b Pedal return spring for pedal stroke sensor 2b 25 DV Housing 27 Breather holes 28 Intake valve 33 Sensor Elements 33a elements, for example, MOSFET 34 Floating objects 35 Mini Storage Containers 36 Shut-off valve for storage container (VB) 37. Aluminum plate or support 38 Main unit 39 Spray Wall 39a cabin 40 Motor Sensors 41a Preload spring for pedal stroke sensor 2a 41b Preload spring for pedal stroke sensor 2b 42 Refill hole for auxiliary piston (16) 43 Chamber of auxiliary piston (16) 44 Hydraulic connection 45 Breather hole of auxiliary piston (16) 46. ​​Intake hole of the pressure supply unit (DV) 47 Refill hole for main cylinder (THZ) 48 Hydraulic connection 49. Piston of the Stroke Simulator (WS) 50 Refill hole for auxiliary piston (16) 51 Refill hole for auxiliary piston plunger (16a) 52 Refill hole for main cylinder (THZ) 53 Refill hole for pressure supply unit (DV) AV exhaust valve ABS B1 Vehicle electrical system connection section 1 B2 Vehicle Electrical System Connection Section 2 BF End Wall Mounting Flange BK Brake Circuit BK1 Brake Circuit 1 BK2 Brake Circuit 2 D Aperture orifice DV Pressure Supply Unit DG Pressure Converter Dr2.1~Dr6.1, Dr8.1 Throttle during return flow to storage container (VB) D1 Auxiliary piston (16) seal 1 D2 Auxiliary piston (16) seal 2 D2.1 Redundant seal (D2) D3 Auxiliary piston plunger (16a) seal D3.1 Redundant seal (D3) D4 SK piston (12) seal 4 D4.1 Redundant seal (D4) D5 SK piston (12) seal 5 D6 Stroke Simulator Piston (49) Seal 6 D6.1 Redundant seal (D6) D7 DV piston (10) seal 7 D8 DV piston (19) seal 8 D8.1 Redundant seal (D8) D9 DV piston (10) additional seal e. Electrical connection e red Redundant electrical connections ECU X Boost control unit (electronic control unit) ECU2 XBoost Partial Redundancy Controller EV Intake Valve ABS FO Fail Operational FV separation valve, normally open HZ Main Cylinder KGT Ball Screw Drive Unit (Spindle) KWS Force-Displacement Sensor MV shut-off valve, normally closed PCB printed circuit board PD1 DV operating chamber (normally closed) solenoid valve Return to storage container VB R is the return line to storage container VB. Check valve directed towards the breather hole of the RV auxiliary piston S1 Vehicle power supply connection section Sn Redundant Vehicle Power Supply Connection Section SK floating circuit ST Plug Connector SV Intake Valve T Target THZ (Tandem Type) Main Cylinder TTL lock time TV1 Brake Circuit 1 (BK1) Separation Valve, normally open TV2 Brake Circuit 2 (BK2) Separation Valve 2, normally open Solenoid valve (normally open) for TV storage container (VB) V Via hole VB Storage Container WA solenoid valve (normally closed) WS Stroke Simulator

Claims

1. A two-box brake system for use in an electric or hybrid vehicle, comprising a first box and a second box, wherein the electric or hybrid vehicle has first and second axles, the first axle being driven by at least one electric drive motor, the first axle being a drive axle having a first wheel brake with a first brake circuit, and the second axle being a non-drive axle having a second wheel brake with a second brake circuit. The two-box brake system comprises a first piston-cylinder unit as part of the first box, and an ESP unit as part of the second box. The first piston-cylinder unit (DV) has an electric drive unit, a transmission device, and a pressure supply piston having one working chamber (11) for supplying a pressure medium to the ESP unit via first and second hydraulic lines, wherein the first hydraulic line is part of the first brake circuit, and the second hydraulic line is part of the second brake circuit. The ESP unit comprises a valve device having a valve, a storage chamber (SpK), and a motor pump unit for supplying a pressure medium to each of the wheel brakes, the valve comprising an intake valve for each of the wheel brakes. The two-box brake system is configured such that when the brakes are applied, at least one of the electric drive motors switches to generator mode, and the generator braking effect is determined accordingly. The brake pressure is determined according to the generator braking effect and the required braking effect. The pressure of each wheel brake is controlled by driving the pressure supply piston and at least one of the valves in the valve device of the ESP unit. The two-wheel blending mechanism operates when the pressure rises, by activating the pressure supply piston, and A) Controlling the intake valve of the second shaft to close and the intake valve of the first shaft to open. and / or, B) Open the intake valve of the first shaft and control the intake valve of the second shaft to be PWM controlled. A two-box brake system implemented by [company name / company name].

2. The two-box brake system according to claim 1, wherein the pressure of the wheel brake is controlled by driving the pressure supply piston of the motor pump unit using the open intake valve of the ESP unit to perform four-wheel blending.

3. The aforementioned two-box brake system is equipped with an electric brake booster, The aforementioned electric brake booster is - Drive system, especially brake pedal and - The first piston-cylinder unit (DV) and, - A second piston-cylinder unit for supplying a pressure medium to at least one of the first and second brake circuits, the second piston-cylinder unit being driven by the drive device, A two-box brake system according to claim 1, having the following features.

4. The two-box brake system according to claim 3, wherein the valve device comprises at least one intake valve, the intake valve being controlled by pulse width modulation (PWM) to perform the two-wheel blending.

5. The two-box brake system according to claim 3 or 4, wherein the second piston-cylinder unit is hydraulically connected to a storage container (VB) via a throttle (D) and a check valve (RV), the throttle and the check valve being arranged in parallel.

6. The electric brake booster comprises a printed circuit board, a storage container, and height sensors (33, 34) disposed in or in contact with the printed circuit board, and the two-box brake system is adapted to perform a continuous evaluation of the liquid height in the storage container (VB) using the height sensors (33, 34) in order to detect a leak early, according to any one of claims 3 to 5.

7. The two-box brake system according to any one of claims 3 to 6, wherein the second piston-cylinder unit is hydraulically connected to at least one of the first and second brake circuits via a valve device comprising first and second valves (FV, FVred), the second valve (FVred) is arranged in series with the first valve (FV) in a hydraulic line connecting the second piston-cylinder unit to the first hydraulic circuit, such that the second piston-cylinder unit can be selectively isolated from the first hydraulic circuit by one of the first and second valves (FV, FVred).

8. The two-box brake system according to any one of claims 1 to 7, further comprising a first separation valve (TV1) in the first hydraulic line to protect the supply of pressure by the first piston-cylinder unit (DV) in the event of a leak in the first brake circuit (BK1).

9. The two-box brake system according to any one of claims 1 to 8, further comprising a second separation valve (TV2) in the second hydraulic line to protect the supply of pressure by the first piston-cylinder unit (DV) in the event of a leak in the second brake circuit (BK2).

10. The aforementioned two-box brake system is In order to protect the pressure supply by the first piston-cylinder unit (DV) in the event of a leak in the first brake circuit (BK1), a first separation valve (TV1) is provided in the first hydraulic line. In order to protect the pressure supply by the first piston-cylinder unit (DV) in the event of a leak in the second brake circuit (BK2), a second separation valve (TV2) is provided in the second hydraulic line. At least one of the separation valves (TV1, TV2) is part of the ESP unit, The two-box brake system according to any one of claims 1 to 7, wherein the at least one separation valve of the ESP unit replaces at least one switching valve (USV1, USV2) of the ESP unit.

11. The aforementioned two-box brake system is In order to protect the pressure supply by the first piston-cylinder unit (DV) in the event of a leak in the first brake circuit (BK1), a first separation valve (TV1) is provided in the first hydraulic line. In order to protect the pressure supply by the first piston-cylinder unit (DV) in the event of a leak in the second brake circuit (BK2), a second separation valve (TV2) is provided in the second hydraulic line. The two-box brake system according to any one of claims 1 to 7, wherein the two-box brake system is adapted to control the separation valves (TV1, TV2) to perform blending separately for the first and second brake circuits (BK1, BK2).

12. The aforementioned two-box brake system is equipped with an electric brake booster, The aforementioned electric brake booster is - Drive system, especially brake pedal and - The first piston-cylinder unit (DV) and, - A second piston-cylinder unit for supplying a pressure medium to at least one of the first and second brake circuits, the second piston-cylinder unit being driven by the drive device, It has, The two-box brake system according to any one of claims 1 to 11, wherein the electric brake booster and the ESP unit each comprise a first ECU and a second at least partially redundant ECU, the first ECU being connected to a first power supply and the second ECU being connected to a second power supply.

13. The two-box brake system according to any one of claims 1 to 12, wherein at least one pressure sensor in the motor pump unit is used to control the drive of the pressure supply piston.

14. The two-box brake system according to any one of claims 1 to 13, wherein the first wheel brake of the first axle, driven by at least one electric drive motor, is connected to the first brake circuit (BK1).

15. One of the first and second shafts is a non-driven axle, The two-box brake system according to any one of claims 1 to 14, wherein when the electric or hybrid vehicle is braked, the pressure in the wheel brake of the non-driven axle is in an increasing phase that is regulated by pulse width modulation (PWM) of at least a portion of the intake valve (EV) of the ESP unit.

16. One of the first and second shafts is a drive axle, The aforementioned two-box brake system is a) Opening the intake valve (EV) assigned to the wheel brake of the drive axle, thereby controlling the electric drive unit of the first piston-cylinder unit (DV), and / or b) Opening the discharge valve (AV) assigned to the wheel brake of the drive axle and controlling the motor pump unit of the ESP unit. The two-box brake system according to claim 15, adapted to reduce hydraulic braking force, wherein the intake valve is controlled by pulse width modulation (PWM).

17. The electric drive unit is a 2x3 phase controlled EC motor equipped with redundant connection parts (e, ered), the two-box brake system according to any one of claims 1 to 16.

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