Control device and method for operating an external power brake system of a vehicle

An external power brake system, including an axle brake module, for a vehicle, comprising:

• a control device, including:
• a primary electronic device configured in such a way that a motor of a motorized piston cylinder device of the external power brake system can be controlled using the primary electronic device such that at least one fluid intake volume of the motorized piston cylinder device can be varied using the controlled motor, and at least one first valve and at least one second valve of the external power brake system can be switched using the primary electronic device, wherein a first wheel brake cylinder of the external power brake system is hydraulically connected to the at least one fluid intake volume at least via the at least one first valve and a second wheel brake cylinder of the external power brake system at least via the at least one second valve,
• wherein the primary electronic device is additionally configured in such a way that a brake pressure maintenance or brake pressure increase function for the first wheel brake cylinder, and a brake pressure reduction function for the second wheel brake cylinder, can be performed simultaneously using the primary electronic device in that at least, while a brake fluid transfer from the first wheel brake cylinder into the at least one fluid intake volume increased using the controlled motor is prevented using the at least one first valve that is switched to be closed, brake fluid from the second wheel brake cylinder can be drawn into the at least one increased fluid intake volume via the at least one second valve that is switched to be at least partially open, and
• a secondary electronic device which is configured in such a way that using the secondary electronic device, in an electrical fault condition of the external power brake system:
• the motor can be controlled such that at least one fluid intake volume of the motorized piston cylinder device can be varied using the controlled motor such that a brake pressure maintenance or brake pressure increase function can be performed for the first wheel brake cylinder and for the second wheel brake cylinder, or
• the at least one first valve and the at least one second valve can be switched such that a brake pressure maintenance or brake pressure increase function can be performed for the first wheel brake cylinder and for the second wheel brake cylinder;
• the motorized piston cylinder device, the motor of motorized piston cylinder device being controlled using the primary electronic device and the secondary electronic device of the control device such that the at least one fluid intake volume of the motorized piston cylinder device can be varied using the controlled motor;
• the first wheel brake cylinder, which can be, or is, arranged on an axle of the vehicle, and the second wheel brake cylinder, which can be, or is, arranged on the axle of the vehicle;
• and
• the first and second valves, configured to be switched using the primary electronic device and the secondary electronic device, wherein the first wheel brake cylinder is hydraulically connected to the at least one fluid intake volume at least via the at least one first valve and the second wheel brake cylinder at least via the at least one second valve.

A method for operating an external power brake system of a vehicle, comprising the following steps:

• simultaneously performing a brake pressure maintenance or brake pressure increase function for a first wheel brake cylinder of the external power brake system arranged on an axle of the vehicle and a brake pressure reduction function for a second wheel brake cylinder of the external power brake system arranged on the axle of the vehicle, at least by performing the following steps:
• controlling a motor of a motorized piston cylinder device of the external power brake system such that at least one fluid intake volume of the motorized piston cylinder device is increased using the controlled motor,
• switching at least one first valve of the external power brake system in such a way that, while the first wheel brake cylinder is hydraulically connected to the at least one fluid intake volume at least via the at least one first valve, a brake fluid transfer from the first wheel brake cylinder into the at least one fluid intake volume increased using the controlled motor is prevented using the at least one first valve that is switched to be closed, and
• switching at least one second valve of the external power brake system in such a way that, while the second wheel brake cylinder is hydraulically connected to the at least one fluid intake volume via the at least one second valve, brake fluid is drawn from the second wheel brake cylinder into the at least one increased fluid intake volume via the at least one second valve that is switched to be at least partially open;
• wherein in then event of an electrical fault condition of the external power brake system, a secondary electronic device is used to either:
• control the motor such that at least one fluid intake volume of the motorized piston cylinder device is varied using the controlled motor such that a brake pressure maintenance or brake pressure increase function is performed for the first wheel brake cylinder and for the second wheel brake cylinder, orswitch the at least one first valve and the at least one second valve such that a brake pressure maintenance or brake pressure increase function is performed for the first wheel brake cylinder and for the second wheel brake cylinder.