Diagnostic method for a braking system

Patent metadata

Field	Value
Publication number	US-10059321-B2
Application number	US-201615133459-A
Country	US
Kind code	B2
Filing date	Apr 20, 2016
Priority date	Apr 21, 2015
Publication date	Aug 28, 2018
Grant date	Aug 28, 2018

Abstract

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.

First claim

What is claimed is:

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, and
all 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; and
performing 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

Assignees

• Ipgate Ag

Inventors

• Van Zanten Anton
• Leiber Heinz

Classifications

• G01M3/2869

  for seals not incorporated in a pipe joint · CPC title

• B60T8/885

  using electrical circuitry · CPC title

• B60T13/662

  characterised by specified functions of the control system components · CPC title

• B60T17/221 Primary

  Procedure or apparatus for checking or keeping in a correct functioning condition of brake systems (hydraulic pressure systems in general F15B19/00, F15B21/04; testing structures or apparatus G01M) · CPC title

• B60T2270/403

  Brake circuit failure · CPC title