A diagnostic method may determine the leak-tightness of at least one seal and/or one valve function in a braking system with at least two brake circuits, following completion of a braking action. The diagnostic method may be carried out at a pressure still present after the braking action in one or
A diagnostic method may determine the leak-tightness of at least one seal and/or one valve function in a braking system with at least two brake circuits, following completion of a braking action. The diagnostic method may be carried out at a pressure still present after the braking action in one or both braking circuits and/or in hydraulic line or a working chamber of a piston-cylinder system or at a lower pressure, or it may be carried out at a pressure of at most 30 bar.
대표청구항▼
1. A diagnostic method for determining the leak-tightness of at least one seal function, at least one valve function, or both, in a braking system with at least two brake circuits, wherein each brake circuit has a brake circuit hydraulic line to which, in each case, at least one wheel brake is conne
1. A diagnostic method for determining the leak-tightness of at least one seal function, at least one valve function, or both, in a braking system with at least two brake circuits, wherein each brake circuit has a brake circuit hydraulic line to which, in each case, at least one wheel brake is connected, wherein the braking system has a regulatable pressure source which serves at least to effect a pressure build-up in the wheel brakes and at least one pressure sensor which determines the pressure in a brake circuit, wherein a control unit controls the valves and the regulatable pressure source, the method comprising: performing, by the control unit, at least one braking diagnostic procedure, the at least one braking diagnostic procedure comprising using one or more pressure measurements, using sensing of brake actuation device travel, or using both, wherein the at least one braking diagnostic procedure is performed following completion of a braking action: either at a pressure which is still present at the completion of the braking action in, or which is input into, the braking system, in one or both brake circuits and/or a hydraulic line or a working chamber of a piston-cylinder system, or at a lower pressure;or at a pressure of at most 30 bar, wherein the pressure is in, or input into, the braking system, in one or both brake circuits and/or a hydraulic line or a working chamber of the piston-cylinder system;wherein during the performing the at least one brake diagnostic procedure, the regulatable pressure source does not cause any change in pressure in one or both of the brake circuits. 2. The diagnostic method according to claim 1, wherein the performing the at least one braking diagnostic procedure is carried out after braking to a vehicle speed zero. 3. The diagnostic method according to claim 2, wherein the performing at least one braking diagnostic procedure comprises at least one diagnostic test, wherein the at least one diagnostic test is only started after an interval of 0.1 to 1 seconds after the vehicle speed reaches zero or after an increase in pressure after the vehicle speed reaches zero, caused by a person who is braking the vehicle. 4. The diagnostic method according to claim 2, wherein in the case of a “soft stop”, a control unit regulates braking pressure in at least one of the at least two brake circuits such that the braking pressure does not fall below a minimum pressure until the vehicle speed reaches zero. 5. The diagnostic method according to claim 1, wherein the performing the at least one braking diagnostic procedure is carried out while the brake actuation device is still being actuated by a person braking the vehicle, wherein the method further includes monitoring, by the control unit, using a sensor, position and/or movement of the actuation device or of a part of the braking system which is coupled mechanically with the actuation device. 6. The diagnostic method according to claim 1, wherein the braking system additionally includes a connecting line which connects together the two brake circuit hydraulic lines of the brake circuits, and at least one switchable valve arranged in the connecting line for selective closure or opening of the connecting line, and wherein the braking system also includes a piston-cylinder arrangement with a working chamber which is limited by an auxiliary piston which is adjustable by means of the brake actuation device, wherein the at least one braking diagnostic procedure includes at least one first diagnostic test that comprises testing leak-tightness or function of at least one seal of a piston, as well as of a further seal of a piston-cylinder system of the braking system, andall outlet valves which are closed during the at least one first diagnostic test, wherein the at least one first diagnostic test includes: determining, using the at least one pressure sensor, a brake pressure, at least at a beginning and at an end of a time period corresponding to the at least one first diagnostic test, wherein the regulatable pressure source does not cause or bring about any change in pressure in the brake circuits between the beginning and the end of the at least one first diagnostic test, and interpreting the occurrence of a brake pressure difference between the determined pressures greater than a predetermined maximum value indicates a leak or malfunction as long as the actuation device has maintained a substantially constant actuation force between the beginning and the end of the at least one first diagnostic test. 7. The diagnostic method according to claim 6, wherein the at least one first diagnostic test further includes, at the beginning of the at least one first diagnostic test, opening a hydraulic line connecting the working chamber with a reservoir, using a valve. 8. The diagnostic method according to claim 6, wherein the braking system additionally includes a connecting line which connects together the two brake circuit hydraulic lines of the brake circuits, and wherein at least one switchable valve is arranged in the connecting line for selective closure or opening of the connecting line, and wherein the braking system includes a piston-cylinder arrangement with a working chamber which is limited by an auxiliary piston which is adjustable by means of the brake actuation device, wherein the at least one brake diagnostic procedure further includes at least one second diagnostic test that comprises testing the leak-tightness or function of at least one seal of the piston-cylinder arrangement,and at least one closed valve which separates the working chamber from a hydraulic line in which a lower pressure is present than in the working chamber, wherein the at least one second diagnostic test includes: determining, using the at least one pressure sensor, a pressure at least at a beginning and at an end of a period of time associated with the at least one second diagnostic test, wherein the regulatable pressure source does not cause or bring about any change in pressure in the brake circuits between the beginning and the end of the at least one second diagnostic test, and interpreting a pressure difference between the determined pressures greater than a predetermined maximum value as indicating a leak or malfunction, as long as the actuation device has maintained a substantially constant actuation force between the beginning and the end of the at least one second diagnostic test. 9. The diagnostic method according to claim 8, wherein the performing the at least one braking diagnostic procedure comprises performing the at least one second diagnostic test immediately after the at least one first diagnostic test. 10. The diagnostic according to claim 8, wherein the at least one second diagnostic test includes, at the beginning of the at least one second diagnostic test, connecting the working chamber with one of the brake circuits by opening a valve, and closing using a valve, or leaving closed, a hydraulic line connecting the working chamber with a reservoir. 11. The diagnostic method according to claim 6, wherein the performing at least one braking diagnostic procedure further comprises: performing one or more further diagnostic tests; andperforming the first diagnostic test at shorter intervals or more frequently than the one or more further diagnostic tests. 12. The diagnostic method according to claim 11, wherein at least one of the one or more further diagnostic tests is carried out at least once at a higher pressure than previous occurrences of the at least one of the one or more further diagnostic tests, wherein the at least one is at least the tenth occurrence. 13. The diagnostic method according to claim 11, further comprising performing at least one of the one or more further diagnostic tests at predetermined intervals at a higher pressure than a pressure used at intervening intervals, between the predetermined intervals, during which the at least one of the one or more further diagnostic tests is also performed. 14. The diagnostic method according to claim 6, wherein at least one first diagnostic test further includes closing a further valve that separates a brake circuit from a hydraulic line at a lower pressure than the brake circuit. 15. The diagnostic according to claim 1, wherein the performing the least one braking diagnostic procedure includes a third diagnostic test that includes testing the leak-tightness or function of at least one seal of the piston-cylinder arrangement,as well as valves sealing an auxiliary piston circuit, wherein the third diagnostic test includes: determining positions of a brake actuation device, using at least one travel sensor, at a beginning and at an end of a time interval associated with the third diagnostic test, wherein during the time interval associated with the third diagnostic test, the brake circuits are pressure-free, and interpreting a difference between the positions determined in the determining exceeding a predetermined maximum value as indicating a leak or malfunction, wherein at the beginning of or before the third diagnostic test, an auxiliary piston circuit is separated from the brake circuits by closing valves, and wherein pressure in the brake circuits is then reduced to zero by opening valves. 16. The diagnostic method according to claim 15, wherein a deviation in the different between the positions that occurs during the third diagnostic test due to an outflow of hydraulic medium via a throttle into a brake circuit or into a reservoir is used in determining the predetermined maximum value used to determine presence of a leak or malfunction. 17. The diagnostic method according to claim 15, wherein the performing at least one braking diagnostic procedure further comprises: following the third diagnostic test closing a solenoid valve as well as inlet valves and thereby increasing pressure in the brake circuits; and at the same time or thereafter opening further solenoid valves and thereby decreasing the pressure in the brake circuits as well as in the working chamber. 18. The diagnostic method according to claim 1, wherein the braking system additionally includes a connecting line which connects together the two brake circuit hydraulic lines of the brake circuits, and at least one switchable valve arranged in the connecting line for selective closure or opening of the connecting line, and wherein the braking system includes a piston-cylinder arrangement with a working chamber which is limited by an auxiliary piston which is adjustable by means of a brake actuation device, wherein the performing at least one braking diagnostic procedure further comprises at least one fourth diagnostic test comprising testing leak-tightness or function of inlet valves of a brake circuit, of a floating piston seal, of an auxiliary piston rod seal, of a solenoid valve, and of a check valve, wherein the at least one fourth diagnostic test comprises, after a vehicle incorporating the braking system has come to a standstill, first closing the inlet valves of the first brake circuit and opening outlet valves of one of the at least two brake circuits, causing pressure in the one of the at least two brake circuits and in a working chamber of a second piston-cylinder system coupled to the piston-cylinder unit to fall, which leads to a reduction in the size of the working chamber of the second piston-cylinder system, until the piston of the second piston-cylinder system reaches an end position; followed by adjusting a piston of the regulatable pressure source to increase pressure in a further brake circuit of the at least two brake circuits until a first time, and halting movement of the piston of the regulatable pressure source at the first time and monitoring pressure in the further brake circuit up until a second time, after the first time; and if the pressure in the further brake circuit does not remain constant during between the first time and the second time, or if a pressure difference measured in the further brake circuit exceeds a predetermined reference value, deciding that a leak or malfunction has occurred. 19. The diagnostic method according to claim 18, wherein the at least fourth diagnostic test further comprises monitoring a position of a double-acting piston, using the control unit; and interpreting movement of the double-acting piston as indicating a leak in the further brake circuit. 20. The diagnostic method according to claim 1, wherein the performing at least one braking diagnostic procedure includes performing at least two diagnostic tests designed to determine if a leak, malfunction or failure is present, wherein if a leak, malfunction or failure is determined by one or more preceding diagnostic tests of the at least two diagnostic tests, a subsequent diagnostic test is modified to be performed at a value of the pressure higher than a value of the pressure at which the subsequent diagnostic test would be performed if the leak, malfunction or failure had not been determined in the one or more preceding diagnostic tests. 21. The diagnostic method according to claim 1, wherein the braking system includes a normally-open 2/2-way solenoid valve configured for diagnosis and pressure reduction.
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이 특허에 인용된 특허 (4)
Yamamoto, Takayuki; Watanabe, Koji; Satou, Takashi, Brake control apparatus.
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