# US 2010/0168979 A1 · Determination of the air play in a brake with two directions application devices > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2010/0168979 A1 - Document ID: US20100168979A1 - Status: Published application - Kind: A1 - Application number: 12/524,094 - Filed: 2008-01-14 - Published: 2010-07-01 - Earliest claimed: 2007-01-30 - Inventors: Christian Baier-Welt; Richard Roberts; Martin Schautt - Web page: https://patentgrep.com/patent/US20100168979A1 ## CPC - F16D 65/14: Actuating mechanisms for brakes; Means for initiating operation at a predetermined position (brake control systems, parts thereof B60T) - F16D 2065/386: {driven electrically} - F16D 2066/005: {Force, torque, stress or strain} - F16D 2121/24: using motors - F16D 2127/10: having wedging elements - F16D: COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES ## Abstract In a method for determining an electrical operating variable, in particular the air play (L) and/or zero position (N) of a brake (1) having a friction element (12) which can be pressed in at least two application directions (A, B) against the friction surface of an element (14) to be braked, the air play or the zero position can be determined in a simple and precise manner by virtue of the friction element (12) being placed into a first and a second point of contact (K1, K2) with the element (14) to be braked, the position x1, x2 of the contact points K1, K2 being detected by means of sensors, and the operating variable (L, N) which is sought being determined therefrom. ## Claims ### Claim 1 A method for determining an operating variable of a brake having a friction element, which can be moved in at least two application directions against the friction surface of an element to be braked, the method comprising the steps of: placing the friction element into a first and a second point of contact with the element to be braked, detecting the position of the contact points by sensors, and determining the operating variable which is sought from the detected positions. ### Claim 2 (depends on 1) The method according to claim 1, wherein, both of the contacts points are approached in the same direction, wherein the direction is the application direction or the release direction, in order to measure the position of the contact points. ### Claim 3 (depends on 1) The method according to claim 1, wherein, the friction element is moved beyond the contact points up to a reversal point. ### Claim 4 (depends on 1) The method according to claim 1, wherein, starting from a released position of the brake the friction element is moved in the direction of the first contact point. ### Claim 5 (depends on 15) The method according to claim 15, wherein, the air gap is calculated according to the following relationship: L=C*(a1*x1−b1*x2)/2. ### Claim 6 (depends on 1) The method according to claim 1, wherein, the zero position is calculated according to the following relationship: N=C*(a2*x1+b2*x2)/2. ### Claim 7 (depends on 1) The method according to claim 1, wherein, an offset of a force sensor is determined. ### Claim 8 (depends on 1) The method according to claim 1, wherein, the operating variable is an air gap and wherein for the determination of the air gap the friction element is moved into only one contact point, whose positions are determined, and the air gap is determined from the position of the contact point and the previously determined zero position. ### Claim 9 (depends on 1) The method according to claim 1, wherein, the method is carried out sequentially at different wheels of a motor vehicle. ### Claim 10 (depends on 15) The method according to claim 15, wherein the air gap has a specified maximum value and when the maximum value is exceeded an adjusting device of the brake is actuated to reduce the air gap. ### Claim 11 (depends on 15) The method according to claim 15, wherein the air gap is compared to a minimum value and when the value falls below the minimum value the air gap is increased by means of an adjusting device. ### Claim 12 (depends on 1) The method according to claim 1, wherein a plausibility check of the sensor signals of a position sensor and of a force sensor is carried out. ### Claim 13 (depends on 12) The method according to claim 12, wherein at least one of the absolute value and the gradient of the sensor signals is compared to specified values. ### Claim 14 A control device for determining an operating variable of a brake having a friction element, which can be moved in at least two application directions against the friction surface of an element to be braked, wherein the control device is operable to place the friction element into a first and a second point of contact with the element to be braked, and comprises sensors to detect the position of the contact points and is further operable to determine the operating variable from said detected positions. ### Claim 15 (depends on 1) The method according to claim 1, wherein the operating variable is at least one of the air gap and the zero position of the brake. ### Claim 16 (depends on 14) The control device according to claim 14, wherein the operating variable is at least one of the air gap and the zero position of the brake. ### Claim 17 (depends on 14) The control device according to claim 14, Wherein both the contacts points are approached in the same direction, wherein the direction is the application direction or the release direction, in order to measure the position of the contact points. ### Claim 18 (depends on 14) The control device according to claim 14, wherein the friction element is moved beyond the contact points up to a reversal point. ### Claim 19 (depends on 14) The control device according to claim 14, wherein starting from a released position of the brake the friction element is moved in the direction of the first contact point. ### Claim 20 (depends on 16) The control device according to claim 16, wherein the air gap is calculated according to the following relationship: L=C*/2.