Control valve, electronically controllable brake system and method for controlling the electronically controllable brake system

A control valve (12) for applying a spring-loaded brake pressure (p3b) to spring-loaded parts (3b) of a rear-axle wheel brake (3), the control valve comprising a first control input and a second control input and a first control chamber, a second control chamber, and a third control chamber,

• wherein the control valve (12) is configured to be pneumatically actuated via the second control input (12b) with a parking-brake control pressure (p5), wherein the parking-brake control pressure (p5) is configured to act in such a manner on control arrangement (14b, 15b, 17c, 22, 23, 24) arranged in a valve housing (12f) of the control valve (12) that a spring-loaded brake pressure (p3b) arises at a working output (12c) of the control valve (12) as a function of the parking-brake control pressure (p5) for implementing a parking-brake braking demand (VP) with the spring-loaded parts (3b) of the rear-axle wheel brakes (3),
• wherein the control valve (12) is further configured to receive, via the first control input (12a), a service-brake control pressure (pV;
• pR) which depends on a service-brake braking demand (VB), wherein the first control input (12a) is connectable to the first control chamber (14a), wherein the first control chamber (14a) is adjustable and operatively connected, via a first control piston (15a), to the control arrangement (14b, 15b, 17c, 22, 23, 24) in the control valve (12) and, during an adjustment of the first control chamber (14a) as a result of pressurization with the service-brake control pressure (pV;
• pR), the spring-loaded brake pressure (p3b) at the working output (12c) is configured to be set as a function of the service-brake control pressure (pV;
• pR) and of the parking-brake control pressure (p5), wherein the first control piston (15a) is furthermore operatively connected to the third control chamber (14c),
• wherein a first compressive force (X1) acts on the first control piston (15a) in a first direction (R1) when the first control chamber (14a) is pressurized with the service-brake control pressure (pV;
• pR), and a second compressive force (X2) in a second direction (R2) opposite to the first direction (R1) acts on the first control piston (15a) when the third control chamber (14c) is pressurized with the same service-brake control pressure (pV;
• pR),
• wherein the control valve further comprises a switchable bypass valve (27) and the first control chamber (14a) is selectively connectable to the third control chamber (14c) depending on a switching position (B1, B2) of the switchable bypass valve (27) for selectively charging the first and third control chambers (14a, 14c) with the same service-brake control pressure (pV;
• pR).