OPERATIONAL METHOD FOR CONTROLLING THE BRAKE PRESSURE GENERATOR OF THE MAIN SYSTEM

Abstract

An operational method for controlling a first brake pressure generator. The operational method includes reading the detected wheel speeds into the brake pressure generator control unit, simulating a control strategy of the secondary control unit for controlling the hydraulic unit based on the wheel speeds so that a brake pressure required at the respective wheel is ascertained, predicting the pressure resulting from the control strategy of the secondary control unit and the brake pressure at the first brake pressure generator, and controlling the first brake pressure generator in accordance with the predicted resulting pressure if the predicted resulting pressure exceeds a limit value, so that the pressure resulting at the brake pressure generator is lower than the predicted pressure due to an activation of the first brake pressure generator.

Claims

1-9. (canceled)

10. An operational method for controlling a first brake pressure generator, which is operated in a main system of a hydraulically closed brake system for a vehicle, the brake system including at least the first brake pressure generator and a brake pressure generator control unit configured to control the first brake pressure generator, and a secondary system, including a second brake pressure generator, a hydraulic unit, and a secondary control unit configured to activate the hydraulic unit and the second brake pressure generator for pressure modulation, the operational method comprising the following steps: reading detected wheel speeds into the brake pressure generator control unit; simulating a control strategy of the secondary control unit for controlling the hydraulic unit based on the wheel speeds so that a brake pressure required at a respective wheel is ascertained; predicting a pressure resulting from the control strategy of the secondary control unit and the brake pressure at the first brake pressure generator; and controlling the first brake pressure generator in accordance with the predicted resulting pressure when the predicted resulting pressure exceeds a limit value, so that the pressure resulting at the brake pressure generator is smaller than the predicted pressure, as a result of an activation of the first brake pressure generator.

11. The operational method as recited in claim 10, wherein the brake pressure generator control unit, when exceeding a probability of a predicted necessary intervention of the secondary control unit, slows down a movement of the first brake pressure generator into a brake pressure increase direction.

12. The operational method as recited in claim 10, wherein the brake pressure generator control unit, in the event of a predicted necessary intervention of the secondary control unit, in the event of an activation of the hydraulic unit, controls the first brake pressure generator in a brake pressure reduction direction, so that the pressure resulting at the first brake pressure generator is reduced.

13. The operational method as recited in claim 10, wherein, following a completed intervention of the secondary control unit, the first brake pressure generator is moved again in a brake pressure increase direction, so that brake pressure is built up.

14. A hydraulically closed brake system for a vehicle, the brake system comprising: a main system; a secondary system, which is hydraulically connected to the main system; a first brake pressure generator configured to generate brake pressure, the first brake pressure generator being situated in the main system; a second brake pressure generator configured to generate brake pressure, the second brake pressure generator being situated in the secondary system; a hydraulic unit situated in the secondary system and by which the brake pressure at a respective wheel is switchable via valves; a secondary control unit, by which the hydraulic unit is controllable based on wheel speeds, so that a pressure modulation is realizable; and a brake pressure generator control unit, situated in the main system and configured to simulate a control strategy of the secondary control unit based on the wheel speeds, and via which the first brake pressure generator is able to be activated.

15. The hydraulically closed brake system as recited in claim 14, wherein the first brake pressure generator is implemented as a plunger system.

16. The hydraulically closed brake system as recited in claim 14, wherein the first brake pressure generator is implemented as an electromechanical brake booster.

17. A vehicle, comprising: a hydraulically closed brake system including: a main system, a secondary system, which is hydraulically connected to the main system, a first brake pressure generator configured to generate brake pressure, the first brake pressure generator being situated in the main system, a second brake pressure generator configured to generate brake pressure, the second brake pressure generator being situated in the secondary system, a hydraulic unit situated in the secondary system and by which the brake pressure at a respective wheel is switchable via valves, a secondary control unit, by which the hydraulic unit is controllable based on wheel speeds, so that a pressure modulation is realizable, and a brake pressure generator control unit, situated in the main system and configured to simulate a control strategy of the secondary control unit based on the wheel speeds, and via which the first brake pressure generator is able to be activated.

18. A non-transitory computer-readable data carrier on which is stored a computer program including program code for use in controlling a first brake pressure generator, which is operated in a main system of a hydraulically closed brake system for a vehicle, the brake system including at least the first brake pressure generator and a brake pressure generator control unit configured to control the first brake pressure generator, and a secondary system, including a second brake pressure generator, a hydraulic unit, and a secondary control unit configured to activate the hydraulic unit and the second brake pressure generator for pressure modulation, the program code, when executed by the brake pressure generator control unit, causing the brake pressure generator control unit to perform: simulating a control strategy of the secondary control unit for controlling the hydraulic unit based on detected wheel speeds of the vehicle so that a brake pressure required at a respective wheel is ascertained.

19. The non-transitory computer-readable medium as recited in claim 18, wherein the program code further causes the brake pressure control unit to perform: predicting a pressure resulting from the control strategy of the secondary control unit and the brake pressure at the first brake pressure generator; and controlling the first brake pressure generator in accordance with the predicted resulting pressure when the predicted resulting pressure exceeds a limit value, so that the pressure resulting at the brake pressure generator is smaller than the predicted pressure, as a result of an activation of the first brake pressure generator.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] FIG. 1 shows an exemplary embodiment of a hydraulically closed brake system for a vehicle for carrying out the operational method of the present invention.

[0025] FIG. 2 shows an exemplary embodiment of the operational method for controlling a first brake pressure generator.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

[0026] FIG. 1 shows an exemplary embodiment of a hydraulically closed brake system 10 for a vehicle for carrying out the operational method of the present invention. The hydraulically closed brake system 10 is illustrated in considerably simplified fashion in this figure. Brake system 10 in this instance comprises a main system 14 and a secondary system 18, which are hydraulically connected to one another via fluid lines 22. A first brake pressure generator 26 is shown in main system 14, which is able to generate a brake pressure. The brake pressure generated in first brake pressure generator 26 is transmitted to secondary system 18 via fluid lines 22.

[0027] Fluid lines 22 are connected in secondary system 18 to a second brake pressure generator 30. In addition to first brake pressure generator 26, second brake pressure generator 30 also builds up brake pressure. Second brake pressure generator 30 is connected to a hydraulic unit 38 via hydraulic unit lines 34. Hydraulic unit 38, which is likewise situated in secondary system 18, is formed by a plurality of hydraulic lines and valves (not shown) switching these hydraulic lines, via which it is possible to activate the respective wheel brakes.

[0028] Additionally, a secondary control unit 42 is situated in secondary system 18. Secondary control unit 42 acquires wheel speeds N.sub.VL, N.sub.VR, N.sub.HL, N.sub.HR, which are measured for example via wheel speed sensors. On the basis of these wheel speeds N.sub.VL, N.sub.VR, N.sub.HL, N.sub.HR, a required brake pressure at the respective wheel is calculated and the valves of hydraulic unit 38 and second brake pressure generator are controlled accordingly. A pressure modulation at the respective wheels is possible in order to implement various functions.

[0029] Additionally, a brake pressure generator control unit 46 is situated in main system 14. This brake pressure generator control unity 46 controls the generated pressure of first brake pressure generator 26. Like secondary control unit 42, brake pressure generator control unit 46 also acquires the wheel speeds N.sub.VL, N.sub.VR, N.sub.HL, N.sub.HR of the wheels. The brake pressure generator control unit 46 thus has the same measurement values as secondary control unit 42.

[0030] On the basis of these wheel speeds N.sub.VL, N.sub.VR, N.sub.HL, N.sub.HR, brake pressure generator control unit 46 simulates the control strategy of secondary control unit 42. As a result, brake pressure generator control unit 46 is familiar with the control of second brake pressure generator 30 and of hydraulic unit 38 performed by secondary control unit 42. Accordingly, the anticipated pressure p.sub.v resulting from the control at first brake pressure generator 26 is estimated on the basis of this simulation.

[0031] On the basis of the predicted pressure p.sub.v, first brake pressure generator 26 is accordingly controlled by brake pressure generator control unit 46 so that the resulting pressure at the first brake pressure generator 26 is smaller than the predicted pressure p.sub.v. This may occur, for example, by a movement of first brake pressure generator 26 in a brake pressure reduction direction.

[0032] FIG. 2 shows an exemplary embodiment of the operational method for controlling first brake pressure generator 26. In a first step 50, wheel speeds N.sub.NV, N.sub.VR, N.sub.HL, N.sub.HR of the wheels of the vehicle are read in. In a subsequent second step 54, a simulation of the control strategy of secondary control unit 42 is performed so that a brake pressure required at the respective wheel is ascertained.

[0033] On the basis of this control strategy and the required brake pressure, the pressure p.sub.v resulting from the control strategy and the brake pressure at first brake pressure generator 26 is predicted in a third step 58. If this predicted pressure p.sub.v is smaller than a limit value p.sub.G, the method begins again with the first step 50. If the predicted pressure p.sub.v is greater than the limit value p.sub.G, brake pressure generator control unit 46 controls the first brake pressure generator 26 in a fourth step 62 in accordance with the predicted pressure p.sub.v.

[0034] First brake pressure generator 26 is controlled so that the subsequently resulting pressure at first brake pressure generator 26 is smaller than the predicted pressure p.sub.v. For example, prior to an activation of hydraulic unit 38, first brake pressure generator 26 is controlled to move in a brake pressure reduction direction. This increases the volume in first brake pressure generator 26 so that the resulting pressure is reduced.

[0035] In addition, it is possible for the control to occur already prior to the actual wheel pressure-reducing intervention of secondary control unit 42 in that a probability for a possible intervention of this control unit 42 is ascertained, as this also occurs in secondary control unit 42, in order to reduce already the wheel pressure buildup speed. If there exists a high probability for a necessary intervention of secondary control unit 42, it is possible to slow down the movement of first brake pressure generator 26 in a brake pressure increase direction already prior to the actual intervention. This reduces a necessary movement in a brake pressure reduction direction so that it is possible to reduce the pressure resulting at first brake pressure generator 26 quickly and effectively.

[0036] In order generate again a sufficient brake pressure following a concluded intervention of secondary control unit 42, the first brake pressure generator may be moved again in a brake pressure increase direction.