Electro-hydraulic Motor Vehicle Brake System And Method For The Operation Thereof

Abstract

An electro-hydraulic motor vehicle brake system is provided, having a first cylinder-piston device, which can be fluidically coupled to at least one wheel brake of the brake system, for generating hydraulic pressure on the at least one wheel brake, wherein the first cylinder-piston device comprises at least one first piston. The brake system further has a second cylinder-piston device, which comprises at least one second piston, and an electromechanical actuator which acts on the second piston of the second cylinder-piston device. The second cylinder-piston device is or can be fluidically coupled at the output side to the first piston of the first cylinder-piston device in order to provide a hydraulic pressure, which is generated in the second cylinder-piston device upon actuation of the electromechanical actuator, for actuating the at least one first piston of the first cylinder-piston device.

What is claimed is: 
     
         1 . An electro-hydraulic motor vehicle brake system, comprising:
 a first cylinder-piston device, which can be fluidically coupled to at least one wheel brake of the brake system, for generating hydraulic pressure on the at least one wheel brake, wherein the first cylinder-piston device comprises at least one first piston;   a second cylinder-piston device, which comprises at least one second piston; and   an electromechanical actuator acting on the second piston of the second cylinder-piston device;   wherein the second cylinder-piston device is or can be fluidically coupled at an output side to the at least one first piston of the first cylinder-piston device in order to provide hydraulic pressure, which is generated in the second cylinder-piston device upon actuation of the electromechanical actuator, for actuating the at least one first piston of the first cylinder-piston device; and   wherein an effective surface of the at least one first piston is greater than an effective surface of the second piston.   
     
     
         2 . The electro-hydraulic brake system according to  claim 1 , wherein the generation of hydraulic pressure on the at least one wheel brake is effected solely by way of the first cylinder-piston device. 
     
     
         3 . The electro-hydraulic brake system according to  claim 1 , further comprising a pedal interface, which can be coupled to a brake pedal, with a third cylinder-piston device which can be selectively coupled to the first cylinder-piston device for generating hydraulic pressure. 
     
     
         4 . The electro-hydraulic brake system according to  claim 3 , wherein the third cylinder-piston device is coupled to the first cylinder-piston device in a push-through operation of the brake system in order to enable a foot-force-dependent actuation of the first piston for generating hydraulic pressure. 
     
     
         5 . The electro-hydraulic brake system according to  claim 1 , wherein the second cylinder-piston device is provided to supply the hydraulic pressure for the hydraulic actuation of the first piston of the first cylinder-piston device in a brake-by-wire operation of the brake system. 
     
     
         6 . The electro-hydraulic brake system according to  claim 5 , wherein the provision of the hydraulic pressure takes place as a function of a detected braking intention or a command from a vehicle dynamics management program. 
     
     
         7 . The electro-hydraulic brake system according to  claim 1 , wherein the first cylinder-piston device and the second cylinder-piston device are fluidically connected in series by way of a fluid path. 
     
     
         8 . The electro-hydraulic brake system according to  claim 1 , wherein the first cylinder-piston device has at least two hydraulic chambers defined by a cylinder and the at least one first piston, wherein a first chamber is fluidically coupled at the inlet side to the second cylinder-piston device, and wherein at least one second chamber can be fluidically coupled to at least one brake circuit of the brake system. 
     
     
         9 . The electro-hydraulic brake system according to  claim 8 , wherein the at least one second chamber comprises two hydraulic chambers, which are arranged in succession in the cylinder and are or can be fluidically coupled in each case to a brake circuit of the brake system. 
     
     
         10 . The electro-hydraulic brake system according to  claim 3 , wherein the third cylinder-piston device can be fluidically coupled to the first cylinder-piston device. 
     
     
         11 . The electro-hydraulic brake system according to  claim 10 , wherein the first cylinder-piston device has at least two hydraulic chambers defined by a cylinder and the at least one first piston, wherein a first chamber is fluidically coupled at the inlet side to the second cylinder-piston device, and wherein at least one second chamber can be fluidically coupled to at least one brake circuit of the brake system, and wherein the third cylinder-piston device can be fluidically coupled to the second cylinder-piston device by way of the first chamber of the first cylinder-piston device. 
     
     
         12 . The electro-hydraulic brake system according to  claim 3 , wherein the first cylinder-piston device and the third cylinder-piston device are arranged in spatial succession. 
     
     
         13 . The electro-hydraulic brake system according to  claim 1 , wherein the first cylinder-piston device and the second cylinder-piston device are arranged substantially spatially parallel to one another. 
     
     
         14 . The electro-hydraulic brake system according to  claim 1 , further comprising a control device or control device system for electrically controlling the electro-mechanical actuator in the brake-by-wire operation. 
     
     
         15 . A method for operating an electro-hydraulic motor vehicle brake system having a first cylinder-piston device, which can be fluidically coupled to at least one wheel brake of the brake system, for generating hydraulic pressure on the at least one wheel brake, wherein the first cylinder-piston device comprises at least one first piston, a second cylinder-piston device having a second piston and having an electro-mechanical actuator acting on the second piston of the second cylinder-piston device, wherein the second cylinder-piston device is or can be fluidically coupled at the output side to the first piston of the first cylinder-piston device, wherein the process comprises the following steps:
 detecting at least one parameter indicating a braking intention on the part of the driver or a need for intervention on the part of the vehicle dynamics management program; and   actuating the second piston of the second cylinder-piston device by means of the electromechanical actuator depending on the detected parameter in order to provide a hydraulic pressure for actuating the first piston of the first cylinder-piston device;   
       wherein the actuation of the second piston is effected taking into account a hydraulic transmission ratio between the first cylinder-piston device and the second cylinder-piston device; and
 wherein the hydraulic transmission ratio is defined in that an effective surface of the at least one first piston is greater than an effective surface of the second piston.