FR2959196A1 - HYDRAULIC BRAKE SYSTEM AND METHOD FOR MANAGING THE SYSTEM - Google Patents

Abstract

Hydraulic brake system comprising: - wheel brake cylinders (9), and a first brake system part (4) and second part (5), and also a first brake pressure generator (35) and a second brake pressure generator (36). The first generator (35) generates a first pressure (403, 503) in the first portion (4, 201a, 201b), and the second generator (36) generates a second pressure (404, 504) in the second portion (5) . The pressure in at least one wheel brake cylinder (9) is adjusted according to a first operating mode by connecting at least one wheel brake cylinder (9) to the first part (4) and / or * a second mode of operation alternately connecting at least one cylinder (9) each time a portion (4).

Description

FIELD OF THE INVENTION The present invention relates to a hydraulic brake system and to a method of managing such a system. State of the art In known brake systems according to the state of the art, the driver establishes, if necessary with the assistance of an active or passive braking force amplifier, a brake pressure via a brake system. a brake master cylinder and a hydraulic unit for applying this pressure to at least one wheel brake cylinder. In the case of control actions for example for the stabilization of the vehicle with an ESP or ABS system, the pressure in a part of the hydraulic brake system concerning the wheel brake cylinder is adjusted or modulates in known manner. To regulate the pressure in the various wheel brake cylinders, pumps and valves are actuated. Such a brake installation is described in the document DE 19925794 A1. This document describes an installation for controlling the brake pressure (or brake pressure), in particular for a road vehicle equipped with a pneumatic brake force amplifier having at least minus two chambers separated from each other and one of which is a low pressure chamber and the other an active chamber cooperating with a brake master cylinder generating a hydraulic pressure with the pneumatic amplifier and a hydraulic unit between the master cylinder and a wheel brake cylinder associated with at least one wheel; the hydraulic unit comprises a switchable valve assembly and a pump. The hydraulic unit hydraulically amplifies the brake pressure and generates the pressure in at least one wheel brake cylinder, which pressure is greater than that prevailing in the master cylinder. DESCRIPTION AND ADVANTAGES OF THE INVENTION The subject of the present invention is a hydraulic brake system comprising: at least one wheel brake cylinder, at least a first part of the brake system and at least a second part of the system; of brake,

At least one first brake pressure generator and at least one second brake pressure generator, the first brake pressure generator generating a first pressure in the first part of the hydraulic brake system and the second pressure generator; brake system generating a second pressure in the second part of the brake system, - the pressure in at least one wheel brake cylinder being adjusted according to, * a first mode of operation by connecting at least one wheel brake cylinder to the first part of the brake system and / or * a second mode of operation alternately connecting at least one wheel brake cylinder each time at least a portion of the two parts of the brake system. In other words, the subject of the invention is a hydraulic brake system consisting of at least a first part and at least a second part of the brake system. The hydraulic brake system comprises at least one wheel brake cylinder, a first and a second brake pressure generator. The first pressure is generated in the first part of the hydraulic brake system by the first brake pressure generator; the second pressure is generated in the second part of the hydraulic brake system by the second brake pressure generator. The pressure applied to a wheel brake cylinder in a first mode of operation is provided by at least one wheel brake cylinder by the first part of the brake system and / or in a second mode of operation by alternately connecting at least one wheel brake cylinder each time at least two parts of the brake system. The first brake pressure generator comprises, for example, a first actuator generating a brake pressure such as a linear motor or a torque motor for actuating a brake cylinder, that is to say a piston / cylinder unit generating the brake pressure (brake pressure).

3 The first brake pressure generator may include a brake force amplifier. Advantageously, a controlled amplifier is used for the brake force. The first brake pressure generator receives the component of the force exerted by the driver of the vehicle and transmitted by an actuating element such as a lever or a pedal. The first brake pressure generator has in the widest direction the conductor at least in the form of the force induced thereby. The first brake pressure generator can take into account the driver only in the form of a desired braking wish without direct transmission of forces to generate the brake pressure. The first actuator of the first brake pressure generator can however also establish a brake pressure independent of the driver. The second brake pressure generator comprises an actuator controlled for example by a control device. The second actuator may also include a motor such as a linear motor or a torque motor. In general, apart from a failure of the first brake pressure generator, in particular of the first actuator, the second brake pressure generator will be generated by the control device, that is to say in a manner independent of the driver. . More precisely the second brake pressure generator operates without the intervention of the force exerted by the driver. The possibility of adjusting the brake pressure of at least one wheel brake cylinder with a first and a second brake pressure generator as well as via a first or a second second part of the brake system, advantageously creates a safety in case of failure so that even if one of the brake pressure generators is defective, the brake system can at least provide a braking effect. Similarly in case of failure of a part of the brake system can always use each of the wheels connected to perform braking. Thus in case of failure of a part of the brake system there will be a backup means for generating the pressure in the wheel brake cylinder.

It is also advantageous that the two brake pressure generators make it possible to generate a pressure in both parts of the brake system with different requirements applied to each brake pressure generator. The first brake pressure generator can be designed to set a high brake pressure but this more slowly than the second brake pressure generator designed to generate lower brake pressures but faster, for example by changing this pressure more quickly . In certain braking situations, for example in the case of a request for rapid modulation of the brake pressure on one or more wheels, in the context of an anti-blocking function of the brake installation, this makes it possible to perform a rapid modulation of the brake pressure by the cooperation between the first and the second brake pressure generator.

The pressure of at least one wheel brake cylinder is set in the first mode of operation by connecting at least one wheel brake cylinder to the first part of the brake system. Such a first mode of operation is for example a normal braking mode. By connecting to the first part of the brake system, there is a pressure in the wheel brake cylinder which depends on the pressure in the first part of the brake system. The term "first mode of operation" here refers to normal operation. In a second mode of operation the pressure of the wheel brake cylinder is adjusted by connecting it alternately to at least two parts of the brake system. This second mode of operation is for example that of anti-lock control or traction control. The second mode of operation can also be that of the automatic tracking operation allowing braking actions to the extent that they are required for example by the control device. The following functions can be applied by the brake system: ABS function, ESP function, ACC function, ASR function. Advantageously, the two parts of the brake system can apply two different pressure levels to the wheel brake cylinder. Thanks to the different operating modes and the type of pressure adjustment linked to them, it is possible, for example, to use the pressure levels prevailing in the parts of the brake system to adjust the pressure of a wheel brake cylinder. . This is provided by the method of the invention. As described, the first pressure generator depends on the conductor or is independent of the conductor to generate the pressure in the first part of the brake system. The second brake pressure generator is independent of the driver to generate the pressure except for the third mode of operation in case of failure of the first brake pressure generator. It is particularly advantageous that the first brake pressure generator operates at the request of the driver. The function can be ensured in this way for normal braking by the hydraulic brake system. In certain operating situations, for example for traction control or braking demand in the case of an automatic tracking mode, the first actuator of the first brake pressure generator may, however, operate independently of the driver so that this function can also be represented by the hydraulic brake system according to the invention. The association of the second brake pressure generator, that is to say the brake pressure generator which is in general independent of the driver, makes it possible to have a function of the hydraulic brake system independent of the driver.

Advantageously this is done as described in connection with the first brake pressure generator that is to say for example with its first actuator because the second brake pressure generator as well as the first actuator are for example controlled by a control device and / or can be adjusted by it. Similarly, however, in the case of anti-lock control, it will be possible to have a pressure rise depending on the conductor generated by the first pressure generator; with the aid of the second brake pressure generator there will be a pressure in the second partial brake system by controlling the second brake pressure generator with the aid of the control apparatus, that is to say

6 independently of the driver. The advantages already mentioned of a different design of the first and the second brake pressure generator including the first and the second actuator will be developed once again. In the third mode of operation which is almost a backup mode, it is expected that the second brake pressure generator, that is to say the second actuator can operate with a set of the driver. According to another development of the brake system according to the invention, the connection between at least one wheel brake cylinder and the first and the second part of the brake system is done by at least one means of interruption or hydraulic interruption. Such means of interruption or hydraulic interruption is for example a valve. It is provided for the case where the brake system comprises a plurality of wheel brake cylinders fitted to different wheels, to associate such a valve to each wheel brake cylinder. If the valve is designed as a switching valve, by actuating the valve it is possible to switch the connection of the wheel brake cylinder to the first and second parts of the brake system. Similarly, the switching can be done using several means of interruption or interruption; for example, each wheel brake cylinder is associated two valves which lead on the one hand to their parts of the brake system but two valves must be switched or set when switching the link. Advantageously, the valve is a switching valve. This switching valve has two positions: in a first position, the corresponding wheel brake cylinder is connected to the first part of the brake system. In a second position the connection is made with the second part of the brake system. Thus and advantageously by switching a single valve can be switched between a first and a second part of the brake system which represents a saving of material and construction time. Advantageously, the first brake pressure generator and the second brake pressure generator are powered by different energy sources. The different energy sources within the meaning of the invention mean that the two brake pressure generators are connected to different onboard sources. it

7 guarantees the safe operation of the brake system even if one of the on-board networks fails. Being alternately connected to different pressure levels of the two parts of the brake system can result in a transfer of brake fluid volume. That is why it is advantageously provided that the hydraulic brake system comprises a system or a volume compensation unit. This system or volume compensation unit connects the first part of the brake system and the second part of the brake system. The volume exchange system can advantageously receive brake fluid volumes from the first part and / or the second part of the brake system and / or transfer brake fluid volumes from the second part of the brake system. brake to the first part of the brake system. Depending on the design of the volume compensation system it is also possible to envisage a transfer in the opposite direction. Volume transfer is generally required in the direction from a portion of the low pressure brake system to the high pressure brake system portion. The volume exchange or compensation system avoids that at a moment there is only too little brake fluid in the brake system in one part of the brake system to ensure braking full. The volume exchange system almost represents the monitoring of the economy of the volume of the brake system. Likewise using the volume compensation system it is possible to transfer back into the exchange or volume compensation system using existing pumps. The system or unit for exchange or volume compensation comprises at least a first hydraulic accumulator associated with the first part of the brake system, at least one second hydraulic accumulator associated with the second part of the brake system, at least one hydraulic pump. backflow and at least one motor driving it. Thanks to the accumulators, pump and motor (s), in the system or unit of exchange or volume compensation, it will be possible to perform the functions of receiving the volume of brake fluid,

8 supply of brake fluid volume and also the volume exchange of brake fluid. The invention also relates to a method of managing a hydraulic brake system in which the hydraulic brake system comprises at least a first part and at least a second part of the brake system and at least one brake cylinder. wheel. The pressure applied to at least one of the wheel brake cylinders is regulated by setting a first pressure in the first part of the brake system, setting a second pressure in the second part of the brake system, establishing a connection between at least one wheel brake cylinder and the first part of the brake system for a first connection time and establishing a connection between at least one wheel brake cylinder and the second part of the brake system for a second connection time. The pressure set in the wheel brake cylinder is for example a set pressure from a setpoint supplied by the control device or a setpoint given by the driver. The pressure in the first part of the brake system is set in the brake system according to the invention by the first brake pressure generator, the pressure in the second part of the brake system is regulated by the second brake pressure generator. . The brake system management method applies four variables: the pressure in the first part of the brake system, the pressure in the second part of the brake system, the first duration of connection and the second duration of connection. With these quantities it is possible to adjust the pressure to a set pressure. These quantities can also be applied to the various operating modes already defined. In a first mode of operation which corresponds to a normal braking, the first duration of connection is as long as normal braking; the first brake pressure corresponds to the pressure set given by the driver. The second link time is then practically zero. In the second mode of operation, according to demand there will be a pressure modulation of at least one wheel, the brake cylinder of

9 corresponding wheel being alternately connected to the two pressure levels for the respective bonding times. In the third mode of operation the situation is reversed; the wheel brake cylinder is connected to the second part of the brake system and there is normal braking. The second duration corresponds to the duration of the braking. The first link duration is almost zero. According to an advantageous development the four control variables mentioned above can be modified to optimally adapt the control variables to the current braking situation. There is also provided an operation in which the wheel brake cylinder is connected to the first part of the brake system for a first time followed by a connection with the second part of the brake system for a second duration and this repeatedly. This allows the pressure to be adjusted as long as there is a demand for pressure adjustment in the second mode of operation described above, and that normal braking or unbraked running has not been achieved.

According to an advantageous development, during the repetition of the sequence of operations described, the four control variables are varied. By varying the control variables during the repetition of the operations, there will be a complete pressure curve on at least one wheel brake cylinder. Since the second actuator which adjusts the pressure in the second part of the brake system is designed to quickly adjust the pressure in the second part of the brake system or to modify it, it will be possible to quickly adapt the pressure curve to the brake cylinder. wheel. This makes it possible to follow any brake pressure demands on a wheel by adjusting it appropriately and especially as quickly as possible after the instruction. The method according to the invention furthermore provides that when a connection is established between the wheel brake cylinder and the first part of the brake system or the second part of the brake system, these parts of the brake system are connected by a system or

10 a balancing unit or brake fluid volume compensation as has already been described. It is intended that the volume compensation system transfers the brake fluid volumes from the first part and / or to the second part of the brake system or brake fluid volumes from the second part of the system to the first part of the system. system. Depending on the design of the volume compensation system it is also possible to have a transfer in the opposite direction. The advantages of this solution have been mentioned above. The invention also relates to a control apparatus for managing the hydraulic brake system. The control apparatus provides at least the pressure to at least one wheel brake cylinder based on signals representing the previous driving situation, the condition of the components of the hydraulic brake circuit and / or a command given by the driver. These quantities are taken into account appropriately to optimally control the brake system and to guarantee the safe operation of the brake system. The control apparatus makes it possible to apply the method according to the invention to manage the brake system as it has been developed. For this, the control device manages the first brake pressure generator, the second brake pressure generator, the breaking or interruption means and the system or compensation unit or volume exchange. The invention also relates to a vehicle equipped with a hydraulic brake system, a control method of the hydraulic brake system and a control apparatus of the hydraulic brake system. In summary, the brake system according to the invention performs the functions of the ESP / ABS / ASR / ACC systems while requiring fewer valves than the known systems; it is more dynamic and is very flexible thanks to the four available control variables.

Drawings The present invention will be described in more detail below with the aid of various embodiments of a hydraulic brake system shown in the accompanying drawings in which: - Figure 1 is a schematic view of a first mode embodiment of the hydraulic brake system according to the invention mainly comprising two brake pressure sensors, a control device, four wheel brake cylinders connected to the hydraulic circuit conduits by solenoid valves and a volume balancing unit. - Figure 2 shows schematically a second embodiment of the hydraulic brake system according to the invention comprising a first brake pressure sensor, a pneumatic brake force controlled amplifier and a tandem master cylinder connected to two circuits each time associated with two wheels. This second embodiment includes an alternative volume balancing unit; FIG. 3 schematically shows a first embodiment of the volume balancing unit as used in the brake system of FIG. 1, - Figure 4 shows the pressure curve of a wheel brake cylinder modulated according to the method of the invention using two pressure levels, - Figure 5 shows the pressure curve for a modulation of 25 pressure on a wheel brake cylinder if the parameters vary ie the pressure level and the duration of connection during the pressure adjustment; - Figure 6 shows schematically the control signals of the first and the second brake pressure sensor and in particular for controlling the first or the second brake pressure sensor; FIG. 7 schematically shows a first embodiment of the compensation or volume balancing unit applied to the brake pressure sensor; brake of Figure 2. 11

DESCRIPTION OF EMBODIMENTS OF THE INVENTION FIG. 1 shows a hydraulic brake system 1 for adjusting the wheel brake pressure of at least one brake 7 of at least one wheel 8. The wheel brake pressure is set at a wheel brake cylinder 9. The wheel brake cylinder is hydraulically connected to two partial brake systems 4, 5. The hydraulic connection of the wheel brake cylinder 9 and at least one partial system brake 4, 5 is by a valve 10. The valve 10 is a switching valve and can alternately connect the wheel brake cylinder 9 to at least a portion of the brake system 4 or 5. For each part of the system 4 or 5 brake can be a separate valve respectively connecting the wheel brake cylinder 9 to each of the brake system parts. Each part of the brake system 4 and / or 5 is equipped with an actuator 2, 3. The actuator makes it possible to adjust the pressure in the part of the brake system 4, 5 respectively connected. The first actuator 2 and the second actuator 3 are electromagnetic actuators such as, for example, direct drives equipped with a linear motor, a torque motor with mechanical deflection or rotary actuators with mechanical conversion, for example with the aid of a pin. To generate the pressure in each connected brake system part, the first actuator 2 is connected to a piston rod 12. The piston rod 12 is connected to a piston 13 mounted to move in a cylinder 14. The cylinder 14 corresponds to a brake cylinder with which the part of the brake system 4 is associated, in particular with the first part of the brake system 4. The cylinder 14 comprises an elastic element 15. It may be for example a spring 15 which according to the embodiment is used to modify the actuating force to be applied to slide the piston 13, to recall the piston 13 after actuation of the brake and / or to modify the return effect for the driver by the brake pedal 19 so that it is in force transmission connection with the piston 13 or can be put in this position of connection. The implementation of the first actuator 2 in particular 35 of an electric motor moves the piston rod 12 so that the piston

13 13 decreases the volume defined in the brake cylinder 14 by the piston 13. The brake fluid in the brake cylinder is moved towards the brake system portion 4, connected. In this way the required pressure pA is obtained in the connected system part 4. Similarly, the second actuator 3 is used with a cylinder / piston unit 16 to establish the pressure. The brake pressure pB is thus generated in the second part 5 of the brake system. The first actuator 2 generates an actuating force FA, 27 applied to the piston 12; the second actuator 3 generates an actuating force FB 28 applied to the corresponding piston to generate the pressure in the brake cylinder 16. By actuating the brake pedal the driver exerts a force 39. The force 39 is both a force for actuating (for a slow movement of the brake pedal) and also a reaction force exerted by the brake system, in particular the first brake cylinder 14, possibly with the return elements but also a brake pedal simulator ( brake sensation simulator) which fully or partially generates the brake pedal return effect for the driver. As an actuating force, the force 39 is directed in the direction of the brake cylinder 14 (this force is not shown in Figure 1) and as a reaction it is directed in the opposite direction of the driver as shown in FIG. FIG. 1. The first and second electromechanical actuators 2 and 3 each receive a supply voltage from the on-board network 34 of the vehicle. It is possible to provide a voltage supply for the first brake actuator 2 and the second brake actuator 3 by separate on-board networks. Both the first actuator 2 and the second actuator 3 can be controlled and / or controlled by a control apparatus 11 through a respective signal transmission line 30, 31.

It is intended to control and / or regulate the first brake actuator 2 by signals 29 from a pedal force sensor 17. It is also provided a regulation and / or control of the first actuator 2 from the signals provided by a stroke sensor. The travel sensor measures the travel of the piston rod 18 connected to the brake pedal 19.

14 sensor is not shown. In the hydraulic brake system 1 according to the embodiment shown there is no direct transmission of the force exerted by the driver on the brake pedal and the piston rod 18 on the piston 13 of the brake cylinder 14. It is also possible to note a set point or wish to brake the driver using the force sensor 17 and a travel sensor (not shown). The force sensor 17, the not shown travel sensor and the piston rod 18 connected to the brake pedal 19 constitute a brake actuating unit 20. The sensors of the brake actuating unit 20 determine the force and the stroke of the brake pedal, the speed at which the brake pedal is actuated and the acceleration of the brake pedal action. These quantities are characteristic signals of a brake setpoint emitted by the driver. According to these magnitudes, the first actuator 2 is controlled. For this purpose, it is intended to directly apply the signals 29 emitted by the brake actuating unit 20 to the first actuator 2. It is also possible to transmit first. the signals of the brake actuation unit 20, in particular those of the sensors of this unit to the control unit 11, if necessary to process the signals and transmit them only subsequently to the first actuator for its control in the form of In this way, the signals of the brake operating unit 20 and thus the driver's brake demand set point for the control of the second actuator 3 are also processed. The second actuator 3 is controlled by the control unit. control 11 to which it is connected by a signal transmission line 31. According to another embodiment of the actuating unit 20 it is possible for the driver to participate in the actuation of the cylinder 14 via of the brake pedal 19 or even that it operates in common with the first actuator 2 in that it moves the piston rod 12, acting alone or in common with the first actuator 2 to thereby participate in the establishment of the brake pressure. For this we can for example provide an element

15 to inject the force exerted by the driver and the force generated by the brake force amplifier including a reaction disk. A detailed description of the possibly common solicitation of the piston rod 12 by the first actuator and the driver will not be detailed here. The first actuator represents such a possibility in the form of a brake force amplifier, for example a hydraulic or pneumatic or electromechanical brake force amplifier. In summary, it is possible to generate the brake pressure pA in the first part 4 of the brake system by generating this pressure pA or only with the aid of the first actuator 2 as a function of a brake wish setpoint emitted by the driver or independently of such a setpoint, or only by the force exerted by the driver or common way by an actuator and the driver. If the brake pressure is generated without intervention of the driver on the piston rod 12, that is to say if the driver limits himself to predefining a brake setpoint by operating the brake pedal 19, there will be a complete decoupling of the driver In particular, the driver actuates with the brake pedal 19 only a pedal simulator, that is to say a simulation unit which creates a pedal reaction effect when the brake pedal and the piston rod 12. brake pedal is actuated. The pedal effect simulator may comprise the sensors already described which determine the brake setpoint emitted by the driver. It is also possible to envisage embodiments in which the driver normally actuates only the simulator unit, in particular a pedal effect simulator, and in the event of failure of the first actuator 2, the piston 12 of the first brake cylinder 14 can always be powered by muscular strength.

It can also be provided that the first actuator controls the first brake cylinder without the driver's instruction that is to say independently of the driver. This is for example the case of an ESP control with action on the brake given by the control unit. The driver does not participate in these conditions to the braking action.

The actuating unit 20, independently of its embodiment with the first actuator 2, the piston 13, the cylinder 14, the piston rod 12 as well as the elastic element 15 constitutes a unit called the first pressure generator. brake 35. This first brake pressure generator 35 generates the pressure pA in the first part 4 of the brake system. This first part of the brake system is hydraulically connected to the cylinder 14. With the cylinder 16 and the piston, the piston rod and the elastic element not shown, the second actuator constitutes a second brake pressure generator 36. This second generator brake pressure 36 generates the pressure in the part 5 of the hydraulic brake system. The characteristic of the first brake actuator 2 as well as that of the second brake actuator 3 can be described using at least one function. For this we distinguish the following case that the driver actuates the first brake cylinder 14 by a muscular force or the case where this actuation is done only through a pedal effect simulator brake. In case the driver actuates the brake cylinder 14 in common with the first actuator 2, the actuation force of the first actuator will be defined by the pedal stroke given by the driver, the speed of the pedal stroke and a signal of a brake force sensor 17 and / or a signal of the control apparatus 11. The dependence between the pedal stroke and the pedal operating speed may be a function dependent on the direction. In this way there will be a relationship (hysteresis) dependent on the direction for the actuation of the brake pedal vis-à-vis the brake pressure prevailing in the connected part of the brake system. With the aid of the force of the actuator and the muscular force exerted by the driver, the brake cylinder 14 is actuated. For this it is necessary for the actuator to exert a force which is at least sufficient to move all the moving masses effectively. system by actuating the brake master cylinder. This corresponds to the load applied to the first actuator 2 and depends on the actual brake pressure of the connected wheel brake cylinder 9 and

Momentarily connected to the brake cylinder 14. If the force is designated FH force 37, the force of the actuator designated FA 27, the moving masses per mi, the acceleration by (a) and the force exerted by the conductor FF the relationship of the co-operating characteristic between the conductor and the first actuator 2 given by the following formula will be: FH + mi a = FF + FA If the driver does not participate in the actuation of the brake cylinders 14 and For the characteristic of the first actuator and for the second actuator, the following formulas will be used: - FH 1 + MI a = FA for the first actuator with a first load FH1 - FH2 + M2 a = FB for the second actuator with A second load FH2 The driver perceives only the characteristic generated by the brake pedal effect simulator: FF = Fsimul + m3a, in this formula m3 represents the masses displaced in the simulator and the mass of the pedal. The characteristic of the actuator force FB of the second brake actuator 3 depends in normal operating mode only on the control apparatus 11, similarly to the characteristic of the first actuator 2. Outside a backup situation in case of failure of the first actuator 2 is not provided a control regardless of the actuation of the brake pedal by the driver. To allow control according to the driver's instruction in such a backup situation, for example by means of the brake pedal, it is intended to control the second actuator by a signal 21 in addition to the instruction provided by the driver. control unit. This signal 21 transmits the instruction of the driver of the first actuator 2 to the second actuator 3. This signal 21 is activated in case of failure of the first brake actuator 2.

In the cooperation between the first brake actuator 2 and the second brake actuator 3, it is also possible to set a first brake pressure pA in the first part 4 of the brake system and the brake pressure to be adjusted depends on the actuation of the brake pedal by the driver; it will also be possible to generate with the second brake actuator 3 a second brake pressure pB in the second part 5 of the brake system, the second brake actuator and thus the second brake pressure pB being predefined by the control device.

The valve 10 then makes it possible to connect a wheel brake cylinder 9 of at least one wheel 8 to one of the two parts of the brake system and thus to transmit the pressure pA of the first part 4 of the brake system or the pB pressure of the second part 5 of the brake system.

It is also possible by switching the valve 10 alternately connect the wheel brake cylinder 9 to one of the parts 4 or 5 of the brake system and thus alternately apply the pressure pA or pB to the cylinder of wheel brake. It is also possible first to apply the pressure pA to the wheel brake cylinder to perform normal braking. In the case of a regulating action, for example an action of the ESP or ABS systems, to modulate different wheel brake pressures, it is possible to adjust the wheel pressure modulation by alternately contacting the wheel brake cylinder 9 with the part 4 or part 5 of the hydraulic brake system. Such an alternating contact with the part 4 or the part 5 of the brake system and thus with the pressure pA or the pressure pB of each of these parts of the brake systems are situations indicated by the sketches associated with the wheels; the detailed description will be made with reference to FIGS. 4 and 5. The pressure set by the alternating connection with the two parts of the brake system is in the pressure range between the pressures pA and ps. To switch at least one valve 10 associated with at least one wheel 8, the control apparatus 11 supplies control or control actuation signals 32 to the valve 10.

19 signals may consist of two sub-signals 32a, b which position the valves so as to make a connection with the first or the second part of the brake system. As the alternating hydraulic connection of at least one wheel brake cylinder 9 with the part 4 or 5 of the brake system applies different pressure levels pA or pB to the wheel brake cylinder, this results in a transfer. of brake fluid volume between parts 4 and 5 of the brake system. To compensate for this transfer of volume there is provided a volume equalization system 6 connected to parts 4 and 5 of the brake system. The volume balancing system 6 will be described hereinafter with reference to FIG. 3. The volume balancing system 6 is connected to the control unit 11 to receive the signals 22 serving for its control and / or its regulation.

In addition to the signals of the brake actuating unit 20 of the first actuator 2, the second actuator 3, actuating signals of at least one valve 10, the control apparatus 11 also receives other necessary signals. to the control of the entire brake system or that can be used in addition.

Thus it is provided inter alia that the control device 11 processes the signals 33 associated with at least one wheel 8, for example the wheel angular velocity w l or a characteristic angle w l indicating the position of the wheel. This is a quantity representing the angle of rotation of the wheel around the hub with reference to an initial position. Thus a rotation of a quarter of the wheel corresponds to an angle of 90 ° or n / 2. The wheel speed w l is obtained by a derivative of the angle as a function of time. For each wheel of the vehicle it will thus be possible to determine the wheel speed and the instantaneous angle. The wheel signals 33 may also be transmitted to the control apparatus as a common signal 38. Compared with the determination of wheel slip as a function of the signals provided by a rotational speed sensor, the determination of wheel slip by the signals using the angle or wheel speed derived therefrom allows modulation

20 faster pressure of the wheel brake cylinder because it does not have to wait for a complete rotation of the wheel to determine the wheel slip. This allows a fast pressure modulation using the hydraulic brake system described and switching between the pressure levels pA and ps because the wheel slip is detected more quickly. The control apparatus may also receive signals such as, for example, signals 24 representing the position of the vehicle, other signals from a wheel speed sensor 23 as well as the steering signals 25 and the control signals of the vehicle. The control apparatus may also receive signals from a pressure sensor in the first or second portion 4, 5 of the brake system. All these variables that can be used to control or regulate the brake system may also already exist in the overall control unit of the vehicle or the hydraulic brake system. It is not essential to provide these signals. The control device may also contain in a memory area, certain functions describing for example the characteristic of a recorded brake action for example in the form of a characteristic curve. Figure 6 gives an overview of the signals supplied to the control apparatus 11 which from these signals control the brake installation. With the aid of the quantities indicated, the control device 11 generates the control signals 30, 31 for the first and the second brake actuator 2, 3 as well as the signals 32 for at least one associated control valve 10 at least 8. By actuating the brake or during stabilization action by the ABS system or the ESP system, the control unit calculates with a program algorithm the brake setpoint pressures. respective wheels. The brake pressures to be adjusted for each connected wheel are transmitted separately. By adjusting the wheel brake pressure, in particular the brake set point pressure by the valve control, the brake pressure can be adjusted individually for each wheel brake cylinder 9. The nature and

The manner in which the pressure is adjusted will be detailed with reference to FIGS. 4 and 5. The brake system as shown can brake both according to the driver's request and also independently of the driver. In the following we will distinguish at least two modes of operation of the brake system. In a first mode of operation which corresponds to normal braking, the driver is decoupled from the two parts of the brake system. The pedal feel for the driver is generated by a pedal stroke simulator that generates the feedback provided to the driver during a braking action. If the driver brakes in a normal braking situation by operating the brake pedal, the first actuator 2 sets the brake pressure pA in the part A of the brake system. However, as already described, it is possible to envisage a participation of the force exerted by the driver to actuate the brake cylinder 14. If this is the case, the driver participates in the establishment of the pressure in that the rod 12 is urged directly or indirectly by the force exerted by the driver. The second mode of operation corresponds to a necessary brake pressure modulation or a brake pressure adjustment. For this, the brake pressure of at least one wheel brake cylinder 9 is adjusted with the first actuator 2 and / or the second actuator 3. In the case of intervention by the ESP system to stabilize the vehicle, the control apparatus 11 acts on the first and / or second actuator to thereby generate a pressure pA in the part 4 of the brake system and a pressure pB in the part 5 of the brake system. In the case of an action of the ESP system the driver does not participate in braking. In the case of a regulation type lock by the control system to prevent the locking of at least one wheel 8, it may be necessary to modulate the wheel brake pressure applied to a wheel brake cylinder 9 to at least one wheel 8. To perform this pressure modulation, a brake pressure pB is generated in the second part 5 of the brake system by means of the second actuator 3 and alternatively connecting by a hydraulic connection at least one

22 wheel brake cylinder 9 to part 4 and part 5 of the brake system. In a third additional mode of operation, which is the emergency operating mode applied in the event of failure of the first actuator, the signals 29 which represent the driver's brake wish setpoint, are applied to the second actuator 3 directly or by the intermediate of the control device 11 and thus provides braking in case of failure of the first actuator 2. If it is intended to urge the piston 12 by the driver in the brake system, in such a case it can operate with the assistance of the motor of the first actuator, if necessary, the brake cylinder 14 with a greater force. Figure 2 shows another embodiment of the brake system according to the invention. As compared with FIG. 1, the driver requests, if necessary with the assistance of a brake force amplifier, a tandem master cylinder 203. The brake force amplifier 204 may be a pneumatic brake force amplifier . It can also be a hydraulic amplifier or an electromechanical amplifier of the brake force. The brake force amplifier may be a controlled and / or regulated amplifier. In the case of a controlled amplifier, the brake cylinder 14 can be actuated without the intervention of the driver, for example in the case where an ESP regulation applies an active pressure, or in the case of a wiper function of the disk. brake or automatic tracking mode. The tandem master cylinder 203 is hydraulically connected to a portion 201 of the brake system. The part 201 of the brake system is dual circuit and it may for example be expected to associate the wheels of the front axle of the vehicle to the brake circuit 201a of the part 201 and the wheels of the rear axle of the vehicle to brake circuit 201b of this part 201. Other distributions of the wheels between the brake circuits of the part 201 of the brake system are possible. For the realization of the amplifier of the brake force 204 and the master brake cylinder 203 no detailed description will be made. The brake pedal or more precisely the actuating unit 202 as described above

23 for actuating the brake system including any sensors necessary for detecting a brake setpoint of the driver, the brake force amplifier 204 and the master cylinder 203 form the first brake pressure generator 35 in its second. embodiment. As a second brake pressure generator 36, analogously to FIG. 1, there is the electromechanical actuator 3 connected to the brake cylinder 16 and the elements already shown in FIG. 1 of the second brake pressure generator 36 also connected to the brake. second part 5 of the brake system. The first brake pressure generator 35 comprising the actuating unit 202, the brake force amplifier 204 and the master cylinder 203 generate a brake pressure pA in the first part 201 of the brake system and the second generator brake pressure 36 generates the brake pressure pB in the second part 5 of the brake system.

The hydraulic brake system shown in FIG. 2 also comprises a volume balancing system 205. The volume balancing system 205 is connected to the brake circuit 201a and to the brake circuit 201b of the first part 201 of the brake system. brake and the second part 5 of the brake system by a hydraulic connection. As already described for the embodiment shown in FIG. 1, it is possible to modulate the pressure in a wheel brake cylinder by alternately connecting the wheel brake cylinder with a valve with the first part of the brake system, in particular with the circuit. brake associated with the first part of the brake system or with the second part of the brake system. As the first part 201 of the brake system is composed of the brake circuit 201a and the brake circuit 201b, the volume compensation unit 205 is made other than the volume compensation unit 6 of the first exemplary embodiment. Both embodiments of the volume compensation unit will be described later. The volume compensation system 6 of the first embodiment and the volume compensation system 205 of the second embodiment may be in the form of a discharge pump.

By alternately connecting the first part 201 and the second part 5 of the brake system the pressure in the wheel brake cylinder is modulated. The application examples described in the first embodiment are also suitable for the second embodiment so that, for example, ABS regulation or ESP regulation apply and the emergency operating mode of the two actuators and thus the braking system. Similarly to the first embodiment, the control device acts by the valves, the second actuator, the volume compensation system and sets the wheel pressure to be adjusted on each of the modulated wheels. For this, the control unit receives the signals already described in connection with the first embodiment. FIG. 4 shows how the method of the invention regulates the pressure of at least one wheel brake cylinder 9. For this, FIG. 4 represents the pressure on the axis 401 and the time on the axis 402. The lines interrupted 403, 404 give the first pressure level for the line 403 and the second pressure level for the line 404. The first pressure level and the second pressure level are set by the first actuator and the second actuator, in particular in each part. 4, 5 of the brake system of the first embodiment and for the second embodiment it is the first part 201 of the brake system and the second part 5 of the brake system. In the exemplary embodiment of the hydraulic brake system, the pressure in the part 201 of the brake system is adjusted not by the first actuator 2 by the brake force amplifier 204 but by the conductor acting on the actuating unit 202 with or without transmission of force to the master cylinder or both in common, again with or without transmission of the force of the driver on the master brake cylinder 203.

FIG. 4 also shows that the first pressure level 403 can be modified. This is indicated by the double arrow 407. The second pressure level 404 can also be modified as indicated by the double arrow 408. Another important quantity for the setting of the pressure is the duration of the link 405 which represents the time during which the wheel brake cylinder receives the

The duration 405 of the connection at the pressure level 403 follows a period or duration of connection 406 at another pressure level, particularly at the lower pressure level 404. From one case to another the actuator corresponding to the high level and that corresponding to the low level of the pressure may vary. The brake pressure in the respective wheel brake cylinder is the average value over the first bonding time, the second bonding time and the pressure levels used. In particular, the resulting brake pressure in a wheel brake cylinder depends on the bonding protocol, i.e. on the succession of bonding times at different pressure levels. FIG. 4 shows four control variables for adjusting the pressure and for representing a connection protocol: the first connection duration 405, the second connection duration 406, the variation of the first pressure level 403, 407 and the variation of the second level 404, 408. The resulting brake pressure in the wheel brake cylinder is not shown in FIG. 4. FIG. 5 shows the variation over time of the wheel brake pressure 505 according to one embodiment. schematic.

Such a variation in the time of the wheel brake pressure may be necessary for example for an action of the ABS system. The axis 501 represents the pressure and the axis 502 the time. The broken line 505 corresponds to the brake pressure set in the wheel brake cylinder and which it is desired to modulate. Line 503 represents the pressure level in the first part 4, 201 of the brake system; line 504 represents the level of pressure in the second part 5 of the brake system. Figure 5 shows that both the duration of the connection at the first pressure level, the duration of the connection at the second pressure level and the first pressure level and the second pressure level can be modulated / modified to adjust the wheel pressure. There is thus a connection protocol for connecting the wheel brake cylinder 9 to different pressure levels of the connected system parts and thus a wheel pressure 505 which varies over time. The setting of

The wheel brake pressure 505 is effected by setting the link protocol using the four command variables mentioned, namely: first link duration, second link duration, first pressure level and / or second pressure level. It is also possible to regulate using sensor signals, for example those of a pressure sensor. FIG. 3 shows the first embodiment of the volume compensation system 6. The volume compensation system 6 comprises a pump 303, a pump motor 304, a hydraulic pressure accumulator 301 and a hydraulic pressure accumulator 302. pressure compensation system 6 is connected to the first part 4 of the brake system by a branch and to the second part 5 of the brake system by a second branch. The connection with the first part 4 of the brake system opens into the hydraulic pressure accumulator 301; the connection with the second part 5 of the brake system opens into the connection of the second hydraulic pressure accumulator 302. A discharge pump 303 is located between the connections of the hydraulic pressure accumulators 301, 302. The discharge pump 303 is driven by the pump motor 304. The pressure accumulator 301 and the pressure accumulator 302 comprise a sensor. The sensors 305 and 306 of the hydraulic pressure accumulators 301 and 302 are accumulator stroke sensors. The accumulator stroke sensors 305 and 306 provide battery stroke sensor signals 307 and 308. The signals 307 and 308 are provided to the controller for controlling and / or regulating the brake system. The control apparatus of the hydraulic brake system also controls the pump motor for the transfer of hydraulic fluid volume in the volume compensation unit 6. The volume compensation unit or system 6 acts as the a volume balancing between the part 4 and the part 5 of the brake system. In the case of normal braking, for example the wheel brake cylinder 9 will be connected to the part 4 of the brake system as shown in Figure 1. If to modulate the pressure in the

27 wheel brake cylinder 9 it must be connected to the second part 5 of the brake system, it switches the valve connecting the wheel brake cylinder 9 to part 4 or part 5 of the brake system. By connecting the wheel brake cylinder 9, for example at the low level in the part 5 of the brake system, this will result in a brake fluid volume transfer from the wheel brake cylinder 9 to the second part 5 of the brake system. brake. To compensate for this transfer of volume, the brake fluid return volume will be received by the hydraulic accumulator 302 associated with the second part 5 of the brake system. The excess volume of brake fluid is thus received when a lower pressure level is connected in the second part 5 of the brake system. In order not to modify the overall economy of the volume of the hydraulic brake system, it is possible to return the brake fluid of the second hydraulic accumulator 302 to put it back to the first pressure level again. For this purpose the motor 304 drives the discharge pump 303 which supplies the brake fluid volume of the second hydraulic accumulator 302 to the first part 4 of the brake system. It is also possible to transfer the brake fluid from the accumulator 302 first to the hydraulic accumulator 301. The level of filling of the hydraulic accumulator 301 or the hydraulic accumulator 302 can be monitored by means of the sensors of accumulator stroke 305, 306 by providing the signals to the controller. The signals 307 and 308 supplied to the control apparatus 11 may also be volume signals. Accurate realization of hydraulic pressure accumulators will not be detailed here. Hydraulic pressure accumulator can also include switchable hydraulic accumulators. Figure 7 shows the volume compensation system 205 used in the second embodiment of the hydraulic brake system 1 according to the invention. This compensation system differs from the first embodiment 6 in that instead of two hydraulic pressure accumulators it comprises three accumulators of hydraulic pressure.

The volume compensation system 205 has three branches 711, 712 and 713. The connections 711 and 712 are associated with the first part of the brake system. The branch 711 is connected to the first brake circuit 201a; the connection 712 is connected to the second brake circuit 201b by a hydraulic connection. The hydraulic connections 711 and 712 are connected to a hydraulic pressure accumulator 701 or 702 as well as each time also to a delivery pump 704, 705. The discharge pumps 704 and 705 are equipped with two motors 706 and 707 to ensure that they 'training. The motors 706 and 707 can be made by a single motor which is not shown. In this case a clutch allows to couple one or the other of the 704 or 705 pumps to this single engine. This allows separate management of the 704 or 705 discharge pumps.

The delivery pump 704 and the delivery pump 705 are hydraulically connected to the third hydraulic pressure accumulator 703. This hydraulic pressure accumulator 703 is itself connected by a hydraulic connection to the connection 713. The pumps 705 and 704 are connected hydraulically by the connection 713. It is assumed that the high pressure prevails in the part 201a, b of the brake system and that the low pressure prevails in the part 5 of the brake system. If a wheel brake cylinder 9 is first connected to the first part 201a, b of the brake system, there will prevail a higher brake pressure than in the second part 5 of the brake system. If, by switching the valve 10 associated with the wheel brake cylinder 9, the wheel brake cylinder 9 is connected to the low pressure level, that is to say with the second part 5 of the brake system, a certain volume of brake fluid will exit the wheel brake cylinder 9 to return to the second portion 5 of the brake system. To enable this transfer of volume, the second part 5 of the brake system is connected to the input 713 of the volume compensation unit or system 205. In the volume compensation unit or system 705, the hydraulic accumulator 710 receives the brake fluid back.

To re-establish the economy of the volume when the first part 201a and / or 201b of the hydraulic brake system is reconnected, the pump 704 and / or the pump 705 make it possible to return the volume of the brake fluid from the hydraulic pressure accumulator 710 to the first part 201 of the brake system. The hydraulic liquid can arrive directly in the part 201a, and / or 201b of the hydraulic brake system but it is also possible to return the hydraulic fluid by the pumps 704 and / or 705 in the hydraulic pressure accumulator 701 and / or 702 In the case of a circuit brake system it is not essential that the same pressure prevails in both brake circuit parts. When the volume of brake fluid is discharged from the hydraulic pressure accumulator 710 in the first part of the brake system, it may be necessary to order the pumps separately and thus to fill the pressure accumulator differently. 701 and / or the pressure accumulator 702 by a different control. For the two embodiments of the system or volume compensation unit 6 or 205 the situation can be summarized as follows: the volume compensation system ensures the reception of the quantities and / or volumes of brake fluid during each switching between the first part and the second part of the brake system. By receiving the excess volume of brake fluid, the unit or system of volume compensation ensures that the position of the pistons or the unrepresented input and output elements of the brake force amplifiers associated with the brake actuators 2, 3 or 202, 203, 204 are substantially independent of the modulation of the brake pressure. In particular the position of the pistons of the brake actuators 2, 3 or 202, 203, 204 is independent of the switching between the first and the second part of the hydraulic brake system and especially the duration of the connection established with each part of the system of brake. The control apparatus 11 receives the volume signals 714, 715, 716 through a signal transmission link 206 or 307 and 308 through the signal transmission link 22 to then process.

These signals. The volume signals indicated above may also be the signals of a respective accumulator stroke sensor which are then mathematically transformed in the control unit to provide volume signals. According to the volume signals of each accumulator, the control unit calculates a control variable applied to the motor driving the respective discharge pump and transmits these signals through the signal transmission links 22 or 206. Thus, by controlling the In the case of discharge pumps, it is ensured that the difference in the volume of brake fluid between the two parts of the brake system remains within an allowed range. The permitted range can be preset in the control unit. The permitted range ensures that in both parts of the brake system there is sufficient brake fluid volume to always allow braking action. The volume compensation systems 6 or 205 may be in the form of a delivery pump in the case of an ABS hydraulic system according to the state of the art. Figure 6 shows schematically a motor vehicle as well as the quantities provided for controlling the first and / or second brake actuator, such that these quantities are used. This figure mainly shows that the first actuator 2 is controlled according to the braking demand setpoint transmitted by the driver. This relationship is schematized by the arrow 602. The driver issues a braking request by operating the brake pedal which moves the piston rod. The first actuator 2 generates the first brake pressure in the first part of the brake system as shown in FIG. 1. The second actuator 3 is controlled with other signals. Thus, the second actuator is controlled inter alia by magnitudes depending on the wheels of the vehicle. Such wheel-dependent variables are, for example, the wheel angle, the rotational speed of the wheel, the pressure of the wheel brake cylinder or the temperature. The wheel brake cylinder can be directly fitted with a pressure sensor or connected to it by a pipe.

The use of at least one wheel angle as a wheel-dependent quantity is a possible solution. As an angle there is the angle corresponding to the position of the wheel for example with respect to a reference position in a coordinate system on which the wheel hub depends. These signals are represented by the signal beam 601. The second actuator can be controlled according to the state of the battery 603 fitted to the vehicle. The battery 603 is a source of rechargeable energy equipping a hydraulic vehicle and / or a hybrid vehicle and in this type of vehicle the battery acts as a regenerative braking system (dynamic braking). In such a regenerative brake system, the hydraulic brake effect must be adapted to the variable brake effect of the regenerative brake system to modify the wheel brake pressure of at least one wheel of the hydraulic brake system. . This adaptation is represented by the presented embodiments of the hydraulic brake system. By contacting at least one wheel with a low pressure level, that is to say by connecting the wheel brake cylinder to the second part of the brake system, it will be possible, for example, to correspondingly reduce the brake pressure in the wheel brake cylinder. As a result, the hydraulic braking effect decreases. As another control quantity of the second actuator, it is possible to use the magnitudes 604 which represent the guidance of the vehicle, for example the steering angle or the steering torque. It is also possible to use the quantities 605 which represent the internal combustion engine of the vehicle, for example its rotational speed, its torque or also the temperature of the engine. The magnitudes 603, 604 and 605 are used to control the second actuator as shown in lines 606. The drawing of FIG. 6 does not imply the direct application of the first and / or second actuator signals. It is possible to use the signals and / or the data via the control device to control and / or regulate the brake system and the distribution of the

Data 602 is retained to control the first actuator and data 601 or 606 to control the second actuator. The other components of FIG. 6 correspond to the components already described with reference to FIGS. 1 and 2. The transmission presented of the signals for controlling the first and / or the second actuator can be transposed for the transmission of the signals serving to control the second actuator as well. in the second embodiment of the hydraulic brake system. In this case, the driver controls by his pedal position and if necessary using the pneumatic brake force amplifier, the first brake pressure in the first part of the brake system, the second actuator being controlled as already described in FIG. using the signals 601, 603, 604 and 605. This embodiment is not shown in the figures.

The braking effect predefined by the position of the brake pedal poses fewer requirements as to the dynamics of the brake pressure setting compared to the requirements for modulating the brake pressure of the driver. Modulating the brake pressure according to wheel-dependent magnitudes, battery-dependent magnitudes, direction-dependent magnitudes, and internal combustion engine-dependent magnitudes requires much greater dynamics. The arrival of the signals used to control the first and the second actuator also provides a different dynamic for the first and the second actuator. The first actuator 2 can generate high brake pressures while the second actuator 3 will be designed to quickly change low brake pressures. In this way the wheel connected, in particular in its wheel brake cylinder will have high pressures but also a rapid modulation of the wheel brake pressure. 35 NOMENCLATURE NOMENCLATURE OF THE MAIN ELEMENTS 1 brake system 2 first actuator 3 second actuator 4 part brake system 5 part brake system 7 wheel brake 8 wheel 9 wheel brake cylinder 10 valve 12 piston rod 13 piston 14 first brake cylinder 15 elastic element 16 piston / cylinder unit 18 piston rod 19 brake pedal 20 brake actuation unit 22 signals 23 steering speed sensor 25 26 engine control signals 27 brake operating force FA 28 brake operating force FB 29 signals 31 transmission link signals 32 control or control actuation signals 32a, b sub-signals first brake pressure generator 36 second brake pressure generator 37 force FH 35 39 for this 201 part of the brake system 201a brake circuit 201b brake circuit 203 tandem master cylinder 204 brake force amplifier 205 system / volume compensation unit 301 hydraulic pressure accumulator 302 hydraulic pressure accumulator 303 pump 304 engine pump 305 stroke sensor 306 stroke sensor 307 stroke sensor signals 308 stroke sensor signals 401 axle 402 axle 403 pressure level 404 pressure level 405 connection time 406 connection time 407 double boom 408 double boom 501 axis 502 axis 504 pressure level 503 pressure level 505 wheel pressure 601 signal beam 602 data 603 battery 604 direction variable / volume 605 variable / motor signals 606 line 701 hydraulic pressure accumulator 35 702 hydraulic pressure accumulator

Claims (2)

CLAIMS 1 °) Hydraulic brake system comprising: - at least one wheel brake cylinder (9), - at least a first part (4, 201a, 201b) of the brake system and at least a second part (5) of the system at least a first brake pressure generator (35) and at least one second brake pressure generator (36), the first brake pressure generator (35) generating a first pressure (403, 503) in the first portion (4, 201a, 201b) of the hydraulic brake system 10, and the second brake pressure generator (36) generating a second pressure (404, 504) in the second brake system portion (5); the pressure in at least one wheel brake cylinder (9) being set according to a first operating mode by connecting at least one wheel brake cylinder (9) to the first brake system part and / or a second mode of operation alternately connecting at least one wheel brake cylinder (9) each time a portion (4, 201a, 201b; 5) at least two parts (4, 201a, 201b; 5) of the brake system. Hydraulic brake system according to claim 1, characterized in that the first brake pressure generator (35) generates the first pressure (403, 503) depending on the conductor or independently of the latter and the second generator brake pressure (36) generates the second brake pressure (404, 504) outside a third mode of operation in case of failure of the first brake pressure generator (35), independently of the conductor. 3) Hydraulic brake system according to claim 1, characterized in that the connection between at least one wheel brake cylinder (9) with the first part (4, 201a, 201b) or the second part (5) of the brake system is via at least one hydraulic interruption means (10) associated with at least one wheel brake cylinder (9). 4 °) hydraulic brake system according to claim 3, characterized in that the hydraulic interruption means (10) is a switching valve. 5 °) hydraulic brake system according to claim 1, characterized in that the first pressure generator (35) and the second pressure generator (36) are supplied with different energies. 6 °) hydraulic brake system according to claim 1, characterized in that the first part (4, 201a, 201b) of the brake system and the second part (5) of the brake system are connected by a volume compensation system (6, 205) which receives the brake fluid volume from the first part (4, 201a, 201b) and / or the second part of the brake system and transfers to the second part of the brake system and / or receive the brake fluid volume of the second part (5) of the brake system to transfer it to the first part (4, 201a, 201b) of the brake system. 7 °) hydraulic brake system according to claim 6, characterized in that the volume compensation system (6, 205) comprises at least one hydraulic accumulator (301, 701, 702) associated with the first part (4, 201a, 201b) of the brake system and at least one second hydraulic accumulator (302, 703) associated with the second brake system portion (5), at least one delivery pump (303, 704, 705) and at least one engine ( 304, 706, 707) .35 38 8 °) A method of managing a hydraulic brake system in which the hydraulic brake system comprises at least a first part (4, 201a, 201b) of the system and at least one second part (5) of the brake system and at least one wheel brake cylinder (9), - the pressure in at least one wheel brake cylinder (9) being regulated by the setting of a first pressure (403, 503) in the first part of the brake system, setting a second pressure (404, 504) in the second part (5) of the brake system, establishing a connection between at least one wheel brake cylinder (9) and the first brake system portion (4, 201a, 201b) during a first linkage period (405) and establishing a connection between at least one wheel brake cylinder (9) and the second brake system portion (5) during a second linkage period (406). Method according to claim 8, characterized in that for adjusting the pressure in at least one wheel brake cylinder (9) the first pressure (403, 503), the second pressure (404, 504), the first link duration (405) and / or the second link duration (406) by varying them. Method according to Claim 8, characterized in that the first pressure (403, 503) is set in the first part of the brake system, the second pressure (404, 504) is adjusted in the second part (5). of the brake system, a connection is made between at least one wheel brake cylinder (9) and the first portion (4, 201a, 20b) of the brake system during a first connection time (405) and a connecting at least one wheel brake cylinder to the second brake system portion (5) during a second linkage period (406). Method according to claims 9 and 10, characterized in that during the repetition the first pressure (403, 503), the second pressure (404, 504), the first connection time (405) and or the second link duration (406). Method according to Claim 8, characterized in that when a connection is made between the wheel brake cylinder (9) and the first part (4, 201a, 20b) of the brake system or the second part ( 5) of the brake system, the parts of the brake system are connected by a volume compensation system (6, 205) and the volume compensation system (6, 205) receives brake fluid volumes from the brake system. first part (4, 201a, 201b) and / or they are received in the second part of the brake system and / or brake fluid volumes are transferred from the second part (5) of the brake system to the first part ( 4, 201a, 201b) of the brake system. 13 °) Control device for managing a hydraulic brake system according to one of claims 1 to 12, characterized in that according to the signals corresponding to the driving situation present (22, 23, 24, 25, 26 , 30, 606, 601, 206), based on the condition of the components of the hydraulic brake system (6, 205, 2) and / or based on a driver instruction (602) a wheel brake pressure is set in at least one connected wheel brake cylinder (9). Control device according to claim 13, characterized in that it adjusts the wheel brake pressure of at least one connected wheel brake cylinder (9) by controlling the first brake pressure generator ( 35) for setting a first pressure (403, 503) in a first part of the system, it controls the second brake pressure generator (36) to set a second pressure (404, 504) in the second part (5) of the system by controlling at least one breaking means (10) to provide a connection between at least one wheel brake cylinder (9) and the first brake system portion (4, 201a, 201b) for a first period of time. link (405) as well as for connecting at least one wheel brake cylinder (9) to the second brake system portion (5) during a second linkage period (406) and controlling the brake compensation system (406). volume (6, 205) .10