Circuit configuration for a brake system having an anti-lock control

• US 5,265,947 A
• Filed: 07/30/1991
• Issued: 11/30/1993
• Est. Priority Date: 02/03/1989
• Status: Expired due to Term

• Current Assignee: Alfred Teves
• Original Assignee: Alfred Teves
• Inventors: Schmidt, Robert, Batistic, Ivica, Buschmann, Gunther, Ehmer, Norbert, Wupper, Hans, Fennel, Helmut
• Primary Examiner(s): Oberleitner, Robert J.
• Assistant Examiner(s): BALLATO, JOSIE
• Application Number:
  US07/730,936
• Time in Patent Office: 854 Days
• Field of Search: 303/100, 303/103, 303/110, 303/DIG. 1, 303/DIG. 2, 303/DIG. 4, 364/426.02
• US Class Current: 303/156
• CPC Class Codes: B60T 8/17616 Microprocessor-based systems
• CPC Class Codes: Y10S 303/04 Pressure signal used in electrical speed controlled braking circuit

Abstract

The circuit configuration for a brake system having an anti-locking control generates pulse-type brake pressure control signals. For pressure rebuild-up after a pressure decrease, brake pressure is applied first at a steep and subsequently at a flatter gradient, this being achieved by a variable pulse (P1) and by short fixed pulses (P2) succeeding one another at a large interval. Circuits are provided rendering dependent the pulse and pulse break times (T₁, T₂, T_k) determining the pressure build-up

on the duration of the pressure build-up (T₁) during the steep-rise build-up in the preceding cycle,

on the duration (T₁ +nT₂) of the entire pressure build-up in the preceding cycle, and

on the duration (T_o) of the preceding pressure decrease, with the pulse times being so dimensioned

that, at a constant coefficient of friction and at a constant static pressure, the locking limit of the wheel is rereached after a predetermined period of time or after a predetermined pulse number. The duration of the variable and of the fixed pressure build-up pulses is computed from the pressure build-up of the preceding pressure or determined from a stored Table.

Claims

1. A circuit for controlling an anti-lock braking system in which pressure in a brake cylinder associated with a wheel to be braked is controlled by inlet and outlet valves in conduits leading to and from the brake cylinder, said circuit comprising:

means adapted for sensing the rotational behavior of said wheel to be braked and for detecting;

(a) a locking limit at which said wheel tends to lock, and

(b) acceleration of said wheel;

means adapted for supplying;

(a) pressure decrease pulses to said inlet and outlet valve means in conduits leading to and from said brake cylinder associated with said wheel to conduct fluid from said brake cylinder during the presence of said pressure decrease pulses while fluid is not conducted to said brake cylinder to decrease pressure in said brake cylinder during the presence of said pressure decrease pulses, and

(b) pressure increase pulse trains to said inlet and outlet valve means to repetitively conduct fluid to said brake cylinder during the presence of pulses of said pressure increase pulse trains while fluid is not conducted from said brake cylinder to increase pressure in said brake cylinder during the presence of said pulses of said pressure increase pulse trains, each of said pressure increase pulse trains having a first pulse and succeeding pulses;

and means for controlling the durations, numbers, and spacings of said pulses of said pressure increase pulse trains according to the following;

(a) for an initial pressure increase pulse train, dependent upon that pressure decrease preceding said initial pressure increase pulse train,

(b) for a particular pressure increase pulse train following said initial pressure increase pulse train, dependent upon that pressure increase preceding said particular pressure increase pulse train,

(c) each said first pulse of said pressure increase pulse trains having a duration which is dependent upon the duration of said preceding pressure decrease and;

(1) the maximum duration of each said first pulse of said pressure increase pulse trains is fixed between forty percent and sixty percent of said duration of said preceding pressure decrease, and

(2) the minimum duration of each said first pulse of said pressure increase pulse trains is fixed between ten percent and thirty percent of said duration of said preceding pressure decrease, and

(d) at an approximately constant coefficient of friction and at an approximately constant static pressure, said locking limit of said wheel is reached after a predetermined period of time.

2. A circuit according to claim 1 wherein increasing the duration of said first pulse in each of said pulse trains is precluded when the duration falls below a predetermined minimum value for a low instantaneous coefficient of friction.

3. A circuit according to claim 1 wherein after the duration of the first pulse in each of said pulse trains is raised to a minimum value, in subsequent pressure increases, renewed pressure increase is precluded if the duration of the pressure increase does not exceed a predetermined threshold.

4. A circuit according to claim 1 wherein after the duration of the first pulse in each of said pulse trains is raised to a minimum value, in subsequent pressure increases, renewed pressure increase is precluded if the number of pulses does not exceed a predetermined threshold.

5. A circuit for controlling an anti-lock baking system in which pressure in a brake cylinder associated with a wheel to be braked is controlled by inlet and outlet valves in conduits leading to and from the brake cylinder, said circuit comprising:

means adapted for sensing the rotational behavior of said wheel to be braked and for detecting;

(a) a locking limit at which said wheel tends to lock, and

(b) acceleration of said wheel;

means adapted for supplying;

(a) pressure decrease pulses to said inlet and outlet valve means in conduits leading to and from said brake cylinder associated with said wheel to conduct fluid from said brake cylinder during the presence of said pressure decrease pulses while fluid is not conducted to said brake cylinder to decrease pressure in said brake cylinder during the presence of said pressure decrease pulses, and

(b) pressure increase pulse trains to said inlet and outlet valve means to repetitively conduct fluid to said brake cylinder during the presence of pulses of said pressure increase pulse trains while fluid is not conducted from said brake cylinder to increase pressure in said brake cylinder during the presence of said pulses of said pressure increase pulse trains, each of said pressure increase pulse trains having a first pulse and succeeding pulses;

and means for controlling the durations, numbers, and spacings of said pulses of said pressure increase pulse trains according to the following;

(a) for an initial pressure increase pulse train, dependent upon that pressure decrease preceding said initial pressure increase pulse train,

(b) for a particular pressure increase pulse train following said initial pressure increase pulse train, dependent upon that pressure increase preceding said particular pressure increase pulse train,

(c) each said first pulse of said pressure increase pulse trains having a duration which is dependent upon the duration of said preceding pressure decrease and;

(1) the maximum duration of each said first pulse of said pressure increase pulse trains is fixed between forty percent and sixty percent of said duration of said preceding pressure decrease, and

(2) the minimum duration of each said first pulse of said pressure increase pulse trains is fixed between ten percent and thirty percent of said duration of said preceding pressure decrease, and

(d) at an approximately constant coefficient of friction and at an approximately constant static pressure, said locking limit of said wheel is reached after a predetermined number of pulses of said pressure increase pulse trains.

6. A circuit according to claim 5 wherein increasing the duration of said first pulse in each of said pulse trains is precluded when the duration falls below a predetermined minimum value for a low instantaneous coefficient of friction.

7. A circuit according to claim 5 wherein after the duration of the first pulse in each of said pulse trains is raised to a minimum value, in subsequent pressure increases, renewed pressure increase is precluded if the duration of the pressure increase does not exceed a predetermined threshold.

8. A circuit according to claim 5 wherein after the duration of the first pulse in each of said pulse trains is raised to a minimum value, in subsequent pressure increases, renewed pressure increase is precluded if the number of pulses does not exceed a predetermined threshold.

9. A circuit for controlling an anti-lock braking system in which pressure in a brake cylinder associated with a wheel to be braked is controlled by inlet and outlet valves in conduits leading to and from the brake cylinder, said circuit comprising:

means adapted for sensing the rotational behavior of said wheel to be braked and for detecting;

(a) a locking limit at which said wheel tends to lock, and

(b) acceleration of said wheel;

means adapted for supplying;

(a) pressure decrease pulses to said inlet and outlet valve means in conduits leading to and from said brake cylinder associated with said wheel to conduct fluid from said brake cylinder during the presence of said pressure decrease pulses while fluid is not conducted to said brake cylinder to decrease pressure in said brake cylinder during the presence of said pressure decrease pulses, and

(b) pressure increase pulse trains having a frequency between 3 Hz and 10 Hz to said inlet and outlet valve means to repetitively conduct fluid to said brake cylinder during the presence of pulses of said pressure increase pulse trains while fluid is not conducted form said brake cylinder to increase pressure in said brake cylinder during the presence of said pulses of said pressure increase pulse trains, each of said pressure increase pulse trains having;

(1) a first pulse having a duration which is variable, and

(2) succeeding pulses having fixed durations and fixed spacings between said succeeding pulses;

and means for controlling the durations, numbers, and spacings of said pulses of said pressure increase pulse trains according to the following;

(a) for an initial pressure increase pulse train, dependent upon that pressure decrease preceding said initial pressure increase pulse train,

(b) for a particular pressure increase pulse train following said initial pressure increase pulse train, dependent upon that pressure increase preceding said particular pressure increase pulse train,

(c) at an approximately constant coefficient of friction and at an approximately constant static pressure, said locking limit of said wheel is reached after a predetermined period of time.

10. A circuit for controlling an anti-lock braking system in which pressure in a brake cylinder associated with a wheel to be braked is controlled by inlet and outlet valves in conduits leading to and from the brake cylinder, said circuit comprising:

means adapted for sensing the rotational behavior of said wheel to be braked and for detecting;

(a) a locking limit at which said wheel tends to lock, and

(b) acceleration of said wheel;

means adapted for supplying;

(a) pressure decrease pulses to said inlet and outlet valve means in conduits leading to and from said brake cylinder associated with said wheel to conduct fluid from said brake cylinder during the presence of said pressure decrease pulses while fluid is not conducted to said brake cylinder to decrease pressure in said brake cylinder during the presence of said pressure decrease pulses, and

(b) pressure increase pulse trains having a frequency between 3 Hz and 10 Hz to said inlet and outlet valve means to repetitively conduct fluid to said brake cylinder during the presence of pulses of said pressure increase pulse trains while fluid is not conducted form said brake cylinder to increase pressure in said brake cylinder during the presence of said pulses of said pressure increase pulse trains, each of said pressure increase pulse trains having;

(1) a first pulse having a duration which is variable, and

(2) succeeding pulses having fixed durations and fixed spacings between said succeeding pulses;

and means for controlling the durations, numbers, and spacings of said pulses of said pressure increase pulse trains according to the following;

(a) for an initial pressure increase pulse train, dependent upon that pressure decrease preceding said initial pressure increase pulse train,

(b) for a particular pressure increase pulse train following said initial pressure increase pulse train, dependent upon that pressure increase preceding said particular pressure increase pulse train,

(c) at an approximately constant coefficient of friction and at an approximately constant static pressure, said locking limit of said wheel is reached after a predetermined number of pulses of said pressure increase pulse trains.

11. A circuit for controlling an anti-lock braking system in which pressure in a brake cylinder associated with a wheel to be braked is controlled by inlet and outlet valves in conduits leading to and from the brake cylinder, said circuit comprising:

means adapted for sensing the rotational behavior of said wheel to be braked and for detecting;

(a) a locking limit at which said wheel tends to lock, and

(b) acceleration of said wheel;

means adapted for supplying;

(a) pressure decrease pulses to said inlet and outlet valve means in conduits leading to and from said brake cylinder associated with said wheel to conduct fluid from said brake cylinder during the presence of said pressure decrease pulses while fluid is not conducted to said brake cylinder to decrease pressure in said brake cylinder during the presence of said pressure decrease pulses, and

(b) pressure increase pulse trains having a frequency between 3 Hz and 10 Hz to said inlet and outlet valve means to repetitively conduct fluid to said brake cylinder during the presence of pulses of said pressure increase pulse trains while fluid is not conducted from said brake cylinder to increase pressure in said brake cylinder during the presence of said pulses of said pressure increase pulse trains, each of said pressure increase pulse trains having;

(1) a first pulse having a duration which is variable, and

(2) succeeding pulses having fixed durations and spacings between said succeeding pulses proportional to said duration of said first pulse of said pressure increase pulse trains;

and means for controlling the durations, numbers, and spacings of said pulses of said pressure increase pulse trains according to the following;

(a) for an initial pressure increase pulse train, dependent upon that pressure decrease preceding said initial pressure increase pulse train,

(b) for a particular pressure increase pulse train following said initial pressure increase pulse train, dependent upon that pressure increase preceding said particular pressure increase pulse train,

(c) at an approximately constant coefficient of friction and at an approximately constant static pressure, said locking limit of said wheel is reached after a predetermined period of time.

12. A circuit for controlling an anti-lock braking system in which pressure in a brake cylinder associated with a wheel to be braked is controlled by inlet and outlet valves in conduits leading to and from the brake cylinder, said circuit comprising:

means adapted for sensing the rotational behavior of said wheel to be braked and for detecting;

(a) a locking limit at which said wheel tends to lock, and

(b) acceleration of said wheel;

means adapted for supplying;

(a) pressure decrease pulses to said inlet and outlet valve means in conduits leading to and from said brake cylinder associated with said wheel to conduct fluid from said brake cylinder during the presence of said pressure decrease pulses while fluid is not conducted to said brake cylinder to decrease pressure in said brake cylinder during the presence of said pressure decrease pulses, and

(b) pressure increase pulse trains having a frequency between 3 Hz and 10 Hz to said inlet and outlet valve means to repetitively conduct fluid to said brake cylinder during the presence of pulses of said pressure increase pulse trains while fluid is not conducted form said brake cylinder to increase pressure in said brake cylinder during the presence of said pulses of said pressure increase pulse trains, each of said pressure increase pulse trains having;

(1) a first pulse having a duration which is variable, and

(2) succeeding pulses having fixed durations and spacings between said succeeding pulses proportional to said duration of said first pulse of said pressure increase pulse trains;

and means for controlling the durations, numbers, and spacings of said pulses of said pressure increase pulse trains according to the following;

(a) for an initial pressure increase pulse train, dependent upon that pressure decrease preceding said initial pressure increase pulse train,

(b) for a particular pressure increase pulse train following said initial pressure increase pulse train, dependent upon that pressure increase preceding said particular pressure increase pulse train, and

(c) at an approximately constant coefficient of friction and at an approxiamtley constant static pressure, said locking limit of said wheel is reached after a predetermined number of pulses of said pressure increase pulse trains.

13. A circuit for controlling an anti-lock braking system in which pressure in a brake cylinder associated with a wheel to be braked is controlled by inlet and outlet valves in conduits leading to and from the brake cylinder, said circuit comprising:

means adapted for sensing the rotational behavior of said wheel to be braked and for detecting;

(a) a locking limit at which said wheel tends to lock, and

(b) acceleration of said wheel;

means adapted for supplying;

(a) pressure decrease pulses to said inlet and outlet valve means in conduits leading to and from said brake cylinder associated with said wheel to conduct fluid from said brake cylinder during the presence of said pressure decrease pulses while fluid is not conducted to said brake cylinder to decrease pressure in said brake cylinder during the presence of said pressure decrease pulses, and

(b) pressure increase pulse trains to said inlet and outlet valve means to repetitively conduct fluid to said brake cylinder during the presence of pulses of said pressure increase pulse trains while fluid is not conducted form said brake cylinder to increase pressure in said brake cylinder during the presence of said pulses of said pressure increase pulse trains, each of said pressure increase pulse trains having a first pulse and succeeding pulses;

and means for controlling the durations, numbers, and spacings of said pulses of said pressure increase pulse trains according to the following;

(a) for an initial pressure increase pulse train, dependent upon that pressure decrease preceding said initial pressure increase pulse train,

(b) for a particular pressure increase pulse train following said initial pressure increase pulse train, dependent upon that pressure increase preceding said particular pressure increase pulse train,

(c) each said first pulse of said pressure increase pulse trains having a duration which is dependent upon a previously measured acceleration of said wheel once said acceleration exceeds a predetermined threshold value, and

(d) at an approximately constant coefficient of friction and at an approximately constant static pressure, said locking limit of said wheel is reached after a predetermined period of time.

14. A circuit for controlling an anti-lock braking system in which pressure in a brake cylinder associated with a wheel to be braked is controlled by inlet and outlet valves in conduits leading to and from the brake cylinder, said circuit comprising:

means adapted for sensing the rotational behavior of said wheel to be braked and for detecting;

(a) a locking limit at which said wheel tends to lock, and

(b) acceleration of said wheel;

means adapted for supplying;

(a) pressure decrease pulses to said inlet and outlet valve means in conduits leading to and from said brake cylinder associated with said wheel to conduct fluid from said brake cylinder during the presence of said pressure decrease pulses while fluid is not conducted to said brake cylinder to decrease pressure in said brake cylinder during the presence of said pressure decrease pulses, and

(b) pressure increase pulse trains to said inlet and outlet valve means to repetitively conduct fluid to said brake cylinder during the presence of pulses of said pressure increase pulse trains while fluid is not conducted from said brake cylinder to increase pressure in said brake cylinder during the presence of said pulses of said pressure increase pulse trains, each of said pressure increase pulse trains having a first pulse and succeeding pulses;

and means for controlling the durations, numbers, and spacings of said pulses of said pressure increase pulse trains according to the following;

(a) for an initial pressure increase pulse train, dependent upon that pressure decrease preceding said initial pressure increase pulse train,

(b) for a particular pressure increase pulse train following said initial pressure increase pulse train, dependent upon that pressure increase preceding said particular pressure increase pulse train,

(c) each said first pulse of said pressure increase pulse trains having a duration which is dependent upon a previously measured acceleration of said wheel once said acceleration exceeds a predetermined threshold value, and

(d) at an approximately constant coefficient of friction and at an approxiamtley constant static pressure, said locking limit of said wheel is reached after a predetermined number of pulses of said pressure increase pulse trains.

15. A circuit for controlling an anti-lock braking system in which pressure in a brake cylinder associated with a wheel to be braked is controlled by inlet and outlet valves in conduits leading to and from the brake cylinder, said circuit comprising:

means adapted for sensing the rotational behavior of said wheel to be braked and for detecting;

(a) a locking limit at which said wheel tends to lock, and

(b) acceleration of said wheel;

means adapted for supplying;

(a) pressure decrease pulses to said inlet and outlet valve means in conduits leading to and from said brake cylinder associated with said wheel to conduct fluid from said brake cylinder during the presence of said pressure decrease pulses while fluid is not conducted to said brake cylinder to decrease pressure in said brake cylinder during the presence of said pressure decrease pulses, and

(b) pressure increase pulse trains to said inlet and outlet valve means to repetitively conduct fluid to said brake cylinder during the presence of pulses of said pressure increase pulse trains while fluid is not conducted from said brake cylinder to increase pressure in said brake cylinder during the presence of said pulses of said pressure increase pulse trains, each of said pressure increase pulse trains having a first pulse and succeeding pulses;

and means for controlling the durations, numbers, and spacings of said pulses of said pressure increase pulse trains according to the following;

(a) for an initial pressure increase pulse train, dependent upon that pressure decrease preceding said initial pressure increase pulse train,

(b) for a particular pressure increase pulse train following said initial pressure increase pulse train, dependent upon that pressure increase preceding said particular pressure increase pulse train, and

(c) at an approximately constant coefficient of friction and at an approximately constant static pressure, said locking limit of said wheel is reached after a predetermined period of time; and

means for initiating pressure increase once acceleration exceeds a predetermined threshold value between 10 g and 20 g if the duration of said preceding pressure decrease was extended and above a predetermined threshold value.

16. A circuit for controlling an anti-lock braking system in which pressure in a brake cylinder associated with a wheel to be braked is controlled by inlet and outlet valves in conduits leading to and from the brake cylinder, said circuit comprising:

means adapted for sensing the rotational behavior of said wheel to be braked and for detecting;

(a) a locking limit at which said wheel tends to lock, and

(b) acceleration of said wheel;

means adapted for supplying;

(a) pressure decrease pulses to said inlet and outlet valve means in conduits leading to and from said brake cylinder associated with said wheel to conduct fluid from said brake cylinder during the presence of said pressure decrease pulses while fluid is not conducted to said brake cylinder to decrease pressure in said brake cylinder during the presence of said pressure decrease pulses, and

(b) pressure increase pulse trains to said inlet and outlet valve means to repetitively conduct fluid to said brake cylinder during the presence of pulses of said pressure increase pulse trains while fluid is not conducted from said brake cylinder to increase pressure in said brake cylinder during the presence of said pulses of said pressure increase pulse trains, each of said pressure increase pulse trains having a first pulse and succeeding pulses;

and means for controlling the durations, numbers, and spacings of said pulses of said pressure increase pulse trains according to the following;

(a) for an initial pressure increase pulse train, dependent upon that pressure decrease preceding said initial pressure increase pulse train,

(b) for a particular pressure increase pulse train following said initial pressure increase pulse train, dependent upon that pressure increase preceding said particular pressure increase pulse train, and

(c) at an approximately constant coefficient of friction and at an approximately constant static pressure, said locking limit of said wheel is reached after a predetermined number of pulses of said pressure increase pulse trains; and

means for initiating pressure increase once acceleration exceeds a predetermined threshold value between 10 g and 20 g if the duration of said preceding pressure decrease was extended and above a predetermined threshold value.