Apparatus and method of testing anti-lock brake system

An apparatus for testing an anti-lock brake system on wheels of a motorcar, said apparatus having rolls for supporting each of the wheels of the motorcar to be tested, means for detecting rotational changes of said rolls for each of said wheels after said motorcar having an anti-lock brake system to be tested is mounted thereon with said wheels of said motorcar placed on said rolls and said anti-lock brake system is actuated after a predetermined speed of said wheels on said rolls has been attained, and means for judging operating conditions of said anti-lock brake system from changes in rotational speed of each of said rolls at a time of braking, wherein:

• a friction coefficient of each of said rolls is set to such a value that a frictional force acting between each of said rolls and each of said wheels at the time of braking exceeds an inertia force of each of said rolls;
• an inertia of each of said rolls is set to such a value that deceleration of each of said wheels at the time of braking can be increased to above a predetermined level required to start an anti-lock control of said anti-lock brake system being tested and that each of said wheels does not stop before the completion of a first braking pressure reduction by said anti-lock control;
• the value of said friction coefficient and the value of said inertia being sufficient to preclude slippage between said wheels and said rolls;
• means for detecting deceleration of each of said rolls;
• means, based on a detected deceleration, for obtaining a braking time required from a time of start of braking operation to a time of stop of each of said rolls;
• means for judging whether said braking time is within a predetermined allowable range;
• and
• means for obtaining the number of deceleration peaks and values of said peaks which are detected during said braking time, said peaks being limited to such peaks which occur when the deceleration changes beyond a predetermined level, and means for comparing obtained number of peaks and obtained values of said peaks with respectively set standard values.

An apparatus for testing an anti-lock brake system on wheels of a motorcar, said apparatus comprising:

• rolls for supporting each of the wheels of the motor car to be tested,
• means for detecting rotational changes of said rolls for each of said wheels after said motorcar having an anti-lock brake system to be tested is mounted thereon with said wheels of said motorcar placed on said rolls and said anti-lock brake system is actuated after a predetermined speed of said wheels on said rolls has been attained;
• means for judging operating conditions of said anti-lock brake system from changes in rotational speed of each of said rolls at a time of braking, wherein:
• a friction coefficient of each of said rolls is set to such a value that a frictional force acting between each of said rolls and each of said wheels at the time of braking exceeds an inertia force of each of said rolls;
• and an inertia of each of said rolls is set to such a value that deceleration of each of said wheels at the time of braking can be increased to above a predetermined level required to start an anti-lock control of said anti-lock brake system being tested and that each of said wheels does not stop before the completion of a first braking pressure reduction by said anti-lock control;
• means for detecting deceleration of each of said rolls;
• means, based on a detected deceleration, for obtaining a braking time required from a time of start of braking operation to a time of stop of each of said rolls;
• and means for judging whether said braking time is within a predetermined allowable range;
• means for obtaining the number of deceleration peaks and values of said peaks which are detected during said braking time, said peaks being limited to such peaks which occur when the deceleration changes beyond a predetermined level, and means for comparing obtained number of peaks and obtained values of said peaks with respectively set standard values;
• and
• means for obtaining an amount of lowering below zero level of deceleration of each of said rolls which occurs at said time of stop of each of said rolls, and means for judging whether said amount of lowering is below a predetermined standard value.

A method of testing an anti-lock brake system in which a vehicle having mounted thereon an anti-lock brake system is run while wheels of said vehicle are on respective rolls and said anti-lock brake system is actuated when a predetermined speed of said rolls has been attained to test said anti-lock brake system, said method comprising the steps of:

• measuring a braking time required from a time of start of braking operation to a time of stop of each of said rolls;
• measuring the number of peaks of deceleration and a value of each of said peaks which occur during said braking time, said peaks being limited to such peaks which occur when said deceleration of said rolls changes beyond a predetermined level;
• and
• comparing said braking time, said number of peaks and said values of peaks, all measured, respectively, in the preceding steps, with respectively set standard values to judge whether said anti-lock brake system is acceptable.