Method for controlling hydraulic volume

Abstract

The invention relates to a method for controlling a hydraulic volume in a system (1) consisting of an external force brake (10) and a driving dynamics regulator (14), the external force brake (10) being hydraulically coupled to the driving dynamics regulator (14). The method comprises the following steps: generating (A) a control signal by means of the driving dynamics regulator (14) and providing a control signal for the external force brake (10) in order to provide a hydraulic volume for the driving dynamics regulator (14). The method further comprises the following steps: carrying out (D) a driving dynamic regulation, after the end of the driving dynamic regulation, returning (E) the hydraulic volume from the driving dynamic regulator (14) to the reservoir (50) via a previously opened circuit separating valve (38, 42) via which the driving dynamic regulator (14) can be connected to the reservoir (50). In addition, the method comprises the steps of closing (G) the circuit separating valve (38, 42) and regulating (H) the brake pressure in the driving dynamics regulator (14) by means of an external force piston (54) arranged in the external force cylinder (52) in the event of starting the active brake mover before or during the guiding (E) of the hydraulic volume.

Description

Technical Field

[0001] The invention relates to a method for controlling a hydraulic volume in a system consisting of an externally powered brake and a vehicle dynamics control system. The invention also relates to a system for controlling a hydraulic volume. Background Art

[0002] In addition to stabilization functions, for example in the form of classic ESP / ABS functions, current vehicle brake systems also include an increasing number of functions, such as driver support or corresponding introduction of force to the brake pedal during brake actuation by an eBKV (electromechanical brake booster) or assistance or partial assistance functions by units for active adjustment of the hydraulic brake pressure (e.g. ESP, eBKV, booster units, etc.) without active driver involvement.

[0003] Driving assistance systems are increasingly being used in today's motor vehicles at various levels of development. They automatically or semi-automatically intervene in the vehicle's drive, control (e.g. steering) or signaling, or warn the driver via a suitable human-machine interface shortly before or during an emergency situation. Typically, the brake system has an electronic brake booster (eBKV) and an ESP system. In this combination, most of the brake system functions can be implemented by the ESP system, and the brake booster is used as an external regulator to increase the dynamic pressure.

[0004] Here, the brake system can work with a closed hydraulic device, that is, the reservoir with hydraulic fluid of the brake system is only used for leakage and temperature compensation, and the available hydraulic volume is therefore constant. Examples for this include classic brake systems, such as vacuum brake boosters, electromechanical brake boosters, such as iBooster or decoupled brake systems (DPB) combined with ESP systems. Alternatively, a brake system, such as an IPB system (IPB: Integrated Braking System), can work with an open hydraulic device. Here, the reservoir with hydraulic fluid can be used to temporarily store hydraulic volume during normal operation. Therefore, during braking, the used hydraulic volume of the brake system may change. The corresponding brake systems have different disadvantages, for example, systems with closed hydraulic devices have the following problem, that is, the suction of the ESP system has more hydraulic volume than the hydraulic volume that should be present in normal operation in the relevant area of ​​the brake system (i.e., the brake cylinder below the master brake cylinder to the wheel) according to the operation. Summary of the invention

[0005] The object of the present invention is to provide a method for controlling the hydraulic volume in a system consisting of an externally powered brake and a vehicle dynamics control system, wherein despite the presence of an externally powered cylinder without a compensating joint, no pressure remains in the brake system when the brake is released.

[0006] This object is achieved by a method for controlling a hydraulic volume having the features according to claim 1. The invention furthermore provides a system having the features according to claim 9. The corresponding dependent claims reflect advantageous developments of the invention.

[0007] The invention provides a method for controlling a hydraulic volume in a system consisting of an externally-powered brake and a driving dynamics controller, wherein the externally-powered brake is hydraulically coupled to the driving dynamics controller. The method comprises the following steps: generating a control signal by the driving dynamics controller; providing the control signal to the externally-powered brake for providing the driving dynamics controller with a hydraulic volume; and performing driving dynamics control. A further step comprises: after the driving dynamics control is completed, the hydraulic volume is returned from the driving dynamics controller via a previously opened circuit separation valve to a reservoir, via which the driving dynamics controller can be connected to the reservoir.

[0008] When an active braking maneuver is initiated before or during the return of the hydraulic volume, the circuit separation valve is closed and the brake pressure in the vehicle dynamics control system is adjusted by means of the external force piston arranged in the external force cylinder.

[0009] After closing the circuit separation valve, the hydraulic volume cannot be discharged due to the lack of a compensation joint on the external force cylinder. Unlike the prior art, the external force cylinder does not additionally introduce a hydraulic volume, but the brake pressure in the driving dynamics regulator is adjusted via the external force piston. The external force piston moves forward or backward for adjustment, so that the corresponding hydraulic volume can be introduced or withdrawn into the driving dynamics regulator. In order to release the brake, the hydraulic volume in the driving dynamics regulator is correspondingly reduced by the backward movement of the external force piston. As a result, the brake can still be released despite the lack of a compensation joint on the external force cylinder and the closed circuit separation valve. Accordingly, no line is required between the compensation joint and the reservoir, thereby saving material and cost. In addition, the structural space of such a system can be reduced.

[0010] In a preferred embodiment of the invention, the circuit separation valve is opened after the control of the driving dynamics has been completed. The circuit separation valve is therefore only opened after the control of the driving dynamics has been completed and if no active braking maneuver has been initiated, so that the hydraulic volume can be directed back to the reservoir. The circuit separation valve is therefore closed during the control of the driving dynamics. If an active braking maneuver must be performed during the control of the driving dynamics, the valves do not have to be closed first, thereby shortening the braking time. In addition, before the active braking maneuver is performed, it can already be determined that the valves will not close in the event of a fault, so that the fault can be reacted to early. This additionally increases safety.

[0011] In another preferred embodiment of the present invention, the circuit separation valve is opened before the driving dynamics control is performed. Therefore, the circuit separation valve is already opened during the driving dynamics control. As a result, the hydraulic volume can be quickly discharged into the reservoir after the driving dynamics control.

[0012] Preferably, the external force piston is moved forward by a stroke before the driving dynamics control is carried out. Thus, hydraulic volume is additionally supplied from the external force cylinder to the driving dynamics control. As a result, the driving dynamics can be quickly supplied with the necessary hydraulic volume. It is also ensured that sufficient hydraulic volume from the driving dynamics control can be accommodated again in the external force cylinder so that the pressure can be reduced there if necessary to release the brake.

[0013] In an advantageous embodiment, after the hydraulic volume has been introduced back, the external force piston is moved backwards by a stroke. Advantageously, the external force piston is moved into a rear end position. The hydraulic brake volume in the external force cylinder is increased by the backward movement of the piston. Thus, after carrying out the method, sufficient brake volume is available so that safe active braking can be carried out.

[0014] Advantageously, the hydraulic volume is adjusted using an external force cylinder without a compensating connection. An external force cylinder without a compensating connection is characterized in that it has no compensating connection, via which the vehicle dynamics control system is connected to the reservoir for returning the hydraulic volume even when the circuit separating valve is closed.

[0015] In a further advantageous embodiment, the vehicle dynamics controller transmits information about the required hydraulic volume together with the control signal. Advantageously, the amount of travel from the front position of the external force piston is adjusted as a function of the required hydraulic volume. This information enables the pressure in the vehicle dynamics controller to be better regulated. It is thus possible to adjust the external force piston in order to ensure that after active braking, the volume can be accommodated again by the external force cylinder. This allows the brake to be released again.

[0016] The problem on which the invention is based is additionally solved by a system for controlling a hydraulic volume in a system consisting of an externally powered brake and a vehicle dynamics control system. The system comprises an externally powered brake, a vehicle dynamics control system hydraulically coupled to the externally powered brake, a control unit for controlling the vehicle dynamics control system, wherein the externally powered brake is coupled to the vehicle dynamics control system in a signal-based manner, and wherein the system is designed to carry out the method according to the invention. Such a device substantially has the advantages described for the method.

[0017] According to a further advantageous embodiment, the externally-forced brake has an externally-forced cylinder without a compensating joint. The above-mentioned advantages are achieved with such an externally-forced brake. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Exemplary embodiments of the invention are shown in the drawings and are explained in more detail in the following description.

[0019] in:

[0020] Figure 1 The system consisting of an external power brake and a vehicle dynamics control system is shown during vehicle dynamics control; and

[0021] Figure 2 An exemplary embodiment of a method for controlling a hydraulic volume in a system consisting of an externally powered brake and a vehicle dynamics control system is shown. DETAILED DESCRIPTION

[0022] Figure 1 The system 1 composed of an external power brake 10 and a driving dynamics controller 14 is shown during driving dynamics control. The system 1 is designed to hydraulically couple the external power brake 10 to the driving dynamics controller 14 via a first and a second coupling valve 18 and 22 of the external power brake and a first and a second coupling valve 26 and 30 of the driving dynamics controller, and thus to form a hydraulic coupling. In this case, the external power brake 10 and the driving dynamics controller 14 are designed as a dual circuit.

[0023] The master cylinder 34 can be manually actuated via a pedal mechanically connected to the master cylinder 34 in order to hydraulically act on the brake cylinders 46a, 46b, 46c and 46d via the first or second circuit separation valve 38 or 42 with the aid of the respectively associated circuit of the vehicle dynamics control system 14 in order to achieve an emergency braking action. The master brake cylinder 34 is hydraulically connected to a reservoir 50 for hydraulic fluid.

[0024] In normal operation, the braking effect on the brake cylinders 46a, 46b, 46c and 46d can be achieved by the external force cylinder 52, in that the external force piston 54 in the external force cylinder 52 displaces the hydraulic volume into the two circuits of the driving dynamics control 14 via the coupling valves 18, 22 of the external force brake. The external force cylinder 52 can be hydraulically coupled to the hydraulic reservoir 50 via the external force cylinder valve 58. The external force cylinder 52 is coupled to the electric motor so that the hydraulic volume can be output or accommodated via the external force cylinder 54. The electric motor can be regulated by a controller coupled to a sensor system for determining the motor position 62. The pressure of the master cylinder 34 can be determined by a pressure sensor 66.

[0025] The master cylinder 34 designed as a dual circuit can be hydraulically coupled to the brake simulator 74 via a brake simulator valve 70 in order to simulate a hydraulic pressure increase for the driver who actuates the brake pedal. In this case, in normal operation, the driving dynamics controller 14 is provided with a hydraulic volume via the external force piston 54 in order to achieve a braking effect on the brake cylinders 46a, 46b, 46c, 46d hydraulically coupled to the driving dynamics controller 14. The mechanical position of the brake pedal can be determined via a pedal travel sensor 78 mechanically coupled to the brake pedal in order to control the external force piston 54.

[0026] The pressure generated by the external force piston 54 is determined by means of the external force piston pressure sensor 82. Via the first and second check valves 86, 90, hydraulic fluid from the reservoir 50 can be supplied to the hydraulic system consisting of the external force brake 10 and the driving dynamics controller 14. The driving dynamics controller 14 is constructed in a known manner, so that a detailed description is omitted.

[0027] Figure 2 Shows the control Figure 1 1 . An embodiment of a method for controlling the hydraulic volume in a system shown in FIG. 1 . In a first step A of the method, a control signal is generated in a control unit of the driving dynamics regulator 14. This control signal is provided for the external force brake 10 so that the hydraulic volume can be provided for the driving dynamics regulator 14. In a second step B, the previously closed circuit separation valves 38 , 42 are opened. As a result, hydraulic fluid from the reservoir 50 can be additionally obtained by the driving dynamics regulator device 14 via the non-return valves 86 , 90. In the next step C, the external force piston 54 is moved forward in the direction of the outlet of the driving dynamics regulator 14. As a result, hydraulic fluid is additionally provided to the driving dynamics regulator 14 via the external force cylinder 52.

[0028] In the following step D, the driving dynamics are regulated in a known manner. After the driving dynamics have been regulated, in the next step E, the hydraulic volume from the driving dynamics regulator 14 is discharged via the open circuit separation valves 38, 42 through the master cylinder 34 into the reservoir 50. With the start of the return, it is monitored whether an active braking maneuver has been initiated via the pedal. If this is not the case, then after the return of the hydraulic volume, in the following step F, the external force piston 54 is moved back again so that sufficient hydraulic fluid is available for the active braking maneuver in the hydraulic cylinder 34. As a result, the brake fluid is moved into the external force cylinder 52 via the external force cylinder valve 58 or via the hydraulic path of the master cylinder 34, the circuit separation valves 38, 42 and the coupling valves 18, 22 of the external force brake.

[0029] Active braking maneuver B should be initiated before or during hydraulic volume return step E. S, in the next step G, the circuit separation valves 38, 42 are closed. Subsequently, in the next step H, the brake pressure in the vehicle dynamics controller is adjusted by means of the external force piston 54. After the active braking maneuver has ended, the external force piston 54 is moved backwards so that the hydraulic volume of the vehicle dynamics controller device 14 is accommodated in the external force cylinder 52. As a result, after the active braking maneuver has ended, the brake cylinders 46a, 46b, 46c, 46d can be released without any brake pressure remaining in the vehicle dynamics controller 14.

Claims

1. A method for controlling a hydraulic volume in a system (1) consisting of an externally powered brake (10) and a vehicle dynamics control system (14), wherein: The external force brake (10) is hydraulically coupled to the driving dynamics regulator (14), and the method comprises the following steps: - generating (A) a control signal by means of the driving dynamics controller (14) and providing a control signal to the external power brake (10) for providing a hydraulic volume to the driving dynamics controller (14); - Carry out (D) driving dynamics control, - after the control of the driving dynamics has been completed, the hydraulic volume is conducted back (E) from the driving dynamics controller (14) via the previously opened circuit separation valve (38, 42) to a reservoir (50), the driving dynamics controller (14) being connectable to the reservoir (50) via the circuit separation valve, - before or during the return (E) of the hydraulic volume, when an active braking maneuver is initiated, the circuit separation valve (38, 42) is closed (G) and the brake pressure in the driving dynamics controller (14) is adjusted (H) using an external force piston (54) arranged in an external force cylinder (52).

2. The method according to claim 1, characterized in that The circuit separating valves (38, 42) are opened after the vehicle dynamics control (H) has been completed.

3. The method according to claim 1, characterized in that The circuit dividing valve (38, 42) is opened (B) before carrying out (D) the regulation of driving dynamics.

4. The method according to any one of the preceding claims, characterized in that The external force piston (54) is moved forward (C) by a stroke before carrying out (D) the regulation of the driving dynamics.

5. The method according to any one of the preceding claims, characterized in that After the hydraulic volume has been returned, the external force piston (54) is displaced rearward (F) by a stroke amount.

6. The method according to any one of the preceding claims, characterized in that The hydraulic volume is adjusted by means of an external force cylinder (52) without a compensating joint.

7. The method according to any one of the preceding claims, characterized in that The vehicle dynamics control system (14) transmits information about the required hydraulic volume together with the control signal.

8. The method according to any one of the preceding claims, characterized in that The stroke amount from the front position of the external force piston (54) is adjusted according to the required hydraulic volume.

9. A system (1) for controlling a hydraulic volume in a system consisting of an externally powered brake (10) and a driving dynamics control system (14), comprising: - external brake (10), a vehicle dynamics control system (14) which is hydraulically coupled to the external power brake (10), - a control unit for controlling the driving dynamics controller (14), in, The external force brake (10) is coupled to the vehicle dynamics control system (14) in a signal-based manner; and the system is designed to carry out the method according to any one of claims 1 to 8.

10. The system (1) according to claim 9, characterized in that The external force brake (10) has an external force cylinder (52) without a compensation joint.

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