Brake system having two pressure-providing devices and method for operating a brake system

A brake installation for a motor vehicle, having four hydraulic wheel brakes which are assigned in each case to one vehicle wheel, comprising:

• a brake pedal, which is assigned a travel sensor arrangement for identifying a braking demand, and having a first and a second pressure provision device for building up brake pressure in the wheel brakes,
• wherein the first pressure provision device is hydraulically connected via a first wheel brake line to a first wheel brake of the four hydraulic wheel brakes assigned to a first brake circuit and is hydraulically connected via a second wheel brake line to a second wheel brake of the four hydraulic wheel brakes assigned to the first brake circuit, and wherein the second pressure provision device is hydraulically connected via a third wheel brake line to a third wheel brake of the four hydraulic wheel brakes assigned to a second brake circuit and is hydraulically connected via a fourth wheel brake line to a fourth wheel brake of the four hydraulic wheel brakes assigned to the second brake circuit, wherein each of the first and second pressure provision devices is respectively activated by an open-loop and closed-loop control unit,
• a first hydraulic connecting line, into which an isolating valve which is open when electrically deenergized is connected, connects one of the first and second wheel brake lines of the first brake circuit to one of the third and fourth wheel brake lines of the second brake circuit, and
• a second hydraulic connecting line, into which an isolating valve which is open when electrically deenergized is connected, connects another one of the first and second wheel brake lines of the first brake circuit to another one of the third and fourth wheel brake lines of the second brake circuit,
• wherein the respective pressure provision device has two pressure chambers, wherein each of the two pressure chambers is hydraulically connected or connectable to a different brake of the same brake circuit.

A method for operating a brake installation for a motor vehicle, having four hydraulic wheel brakes which are assigned in each case to one vehicle wheel,

• having a brake pedal which is assigned a travel sensor arrangement for identifying a braking demand,
• and having a first and a second pressure provision device for building up brake pressure in the wheel brakes,
• wherein the first pressure provision device is hydraulically connected via a wheel brake line to a first wheel brake of the four hydraulic wheel brakes assigned to a first brake circuit and is hydraulically connected via a wheel brake line to a second wheel brake of the four hydraulic wheel brakes assigned to the first brake circuit, and wherein the second pressure provision device is hydraulically connected via a wheel brake line to a third wheel brake of the four hydraulic wheel brakes assigned to a second brake circuit and is hydraulically connected via a wheel brake line to a fourth wheel brake of the four hydraulic wheel brakes assigned to the second brake circuit,
• and wherein each of the first and second pressure provision devices is respectively activated by a separate respective open-loop and closed-loop control unit,
• a first hydraulic connecting line, into which an isolating valve which is open when electrically deenergized is connected, connects one of the wheel brake lines of the first brake circuit to one of the wheel brake lines of the second brake circuit, and
• a second hydraulic connecting line, into which an isolating valve which is open when electrically deenergized is connected, connects another one of the wheel brake lines of the first brake circuit to another one of the wheel brake lines of the second brake circuit,
• wherein, in a normal situation, when each of the isolating valves are closed and pressure can be built up by both pressure provision devices, building up pressure in the wheel brakes of only the first brake circuit with exactly one pressure provision device, and building up pressure in the wheel brakes of only the second brake circuit only by the other pressure provision device.