Disc brake having a clearance-monitoring device, and method for monitoring clearance

A method for monitoring a clearance of a disc brake having

• brake pads,
• a brake-application device having a brake lever,
• an adjustment device coupled to the brake-application device in order to adjust for wear of the brake pads and the brake disc,
• a wear sensor configured to detect a wear value of the brake pads and the brake disc,
• at least one temperature sensor,
• a brake control unit, and
• a clearance-monitoring device comprising a control device connected to the wear sensor, the brake control unit and at least one temperature sensor, and
• the clearance monitoring device being configured to evaluate measured values from at least the wear sensor and the at least one temperature sensor, identify secondary conditions based on signals from the at least one temperature sensor, learn and estimate trends, and include characteristic variables of the disc brake in the evaluation of the measured values,
• wherein the wear sensor includes a pick-up element in the form of a potentiometer whose electrical resistance is variable is response to rotation of a driver shaft of the adjustment device, the pick-up element is configured to generate a signal in the form of an electrical voltage which is proportional to the rotation of the driver shaft, and the disc brake characteristic variables includes a brake pressure,
• the method comprising the acts of:
• a) forming current value pairs from current brake pressure values and detected current signal values received by the control unit of the wear sensor during a braking process;
• b) comparing the formed current value pairs with reference values previously stored at the control unit;
• c) evaluating with the control unit the comparison in a manner that includes thermal influences based on signals from the at least one temperature sensor, and
• d) determining from the comparison evaluation whether the clearance has changed and whether to output indicative of the clearance,
• wherein in the comparing of the current value pairs, the clearance monitoring device is configured to issue signals indicative of a current clearance state based on comparison of a current brake pressure value and wear sensor information, where
• the brake pressure pair includes the current brake pressure and a nominal brake pressure present when the brake pads contact the brake disc,
• the pick-up device voltage pair includes the pick-up device voltage signal and a nominal voltage corresponding to a position of the pick-up device potentiometer when the brake pads contacted the brake disc in a preceding brake application,
• if the current brake pressure equals the nominal brake pressure, and the pick-up device voltage signal equals the nominal voltage, the clearance is evaluated as correct and a clearance correct signal is issued,
• if the current brake pressure value is greater than the nominal brake pressure, and the pick-up device voltage signal is greater than the nominal voltage, the clearance is evaluated as too large and a clearance adjustment signal is issued, and
• if the current brake pressure value is less than the nominal brake pressure, and the pick-up device voltage signal is less than the nominal voltage, the clearance is evaluated as undershot and a clearance warning signal is issued.