DE2362352A1 - ANTI-LOCK BRAKING SYSTEM - Google Patents

Description

558058 *

Kelsey-Hayes Company

38481 Huron River "Drive
Romulus. Me. 48174, USA

December 14, 1973 Attorney File M-2889

Anti-lock braking system

The invention relates to an anti-lock braking system for a " multi-wheeled, in particular four-wheeled motor vehicle.

Overall, the invention creates an anti-lock braking system in which a conventional lock controller only applies to one pair of wheels is assigned, while the blocking control of the other pair of wheels takes place in that the other pair of wheels is the one pair of wheels readjusted during the lock-regulated braking will. The invention is particularly advantageous in current ones Brake systems with split hydraulic circuits for the door and rear wheels can be used, as they are compared to a four-wheel lock controller creates a considerable reduction in the construction costs for the electronic components. Through the invention

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• A desired blocking control is achieved and either the rear wheel set follows the front wheel set or vice versa.

Further details and features of the invention will emerge from the claims and the following description in conjunction with the drawings. It shows:

Fig. 1 is a schematic circuit diagram of an according to the invention trained anti-blocking system;

Pig. FIG. 2 is a schematic diagram showing additional details of the anti-lock braking system according to FIG 1 shows;

Fig. 5 is a schematic circuit diagram of another embodiment of the invention;

4 shows a schematic circuit diagram of a "further embodiment the invention. -

The anti-lock braking system according to FIG. 1 is for a vehicle with two rear wheels 10, 12 and two front wheels 14, 16 can be used. Wheel brakes 10b, 12b, 14b and 16b are assigned to the baths 10 to 16 and are operated by a split master cylinder 18, the front brakes 14b, 16b and the rear brakes 10b, 12b

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are engaged via two separate pressure medium circuits. Of the Master cylinder 18 can be used by the driver using the brake pedal are actuated 'and is used to supply pressure medium for actuation the wheel brakes. "" · .-.

The anti-lock braking system contains a main control stage 20 for the Rear wheels 10 and 12 and a follow-up control stage 22 for the front wheels 14 and 16. A rear wheel brake pressure modulator 24 for the rear wheels 10 and 12, via brake fluid lines 28 and 30, respectively, between the master cylinder 18 and the brakes 10b and 12b switched on. .A front brake pressure modulator 26 is over Brake medium lines 32 and 34 switched on between the master cylinder 18 and the front wheel brakes 14b and 16b, respectively. During the When braking, the master cylinder 18 presses the brake means via the line 28, the rear wheel modulator 24 and the line 30 Actuation of the rear wheel brakes 10b and 12b as well as via the line 32, the modulator 26 and the line 34 for engaging the Yorderradbremsen 14b, 16b.

The main control stage 20 and the readjustment stage 22 are via lines 20a and 22a are connected to modulators 24 and 26, respectively. During the braking process, the stages 20, 22 generate signals via the lines 20a and 22a, making the modulators 24 and 26 at Determination of an impending slip condition on the rear wheels IO and 12 are operated.

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BATH ORIGINAL '

The anti-lock braking system also includes a rear wheel 'turning. counter 36 and front wheel speed sensor 38 and 40. The speed sensor 36 is connected to the drive shaft of the differential gear and via a line 42 to the main control stage 20 connected. The speed sensor 36 generates a signal that the represents mean speed of rear wheels 10 and 12, and this signal reaches the main control stage 20 via the line 42 as an input signal. The speed sensor 36 can, for example Generate pulses with a frequency corresponding to the speed of the drive shaft. The speed sensor 38 is assigned to the front wheel 14 and connected to the readjustment stage 22 via a line 44, and the speed sensor 40 is assigned to the front wheel 16 and connected to the next control stage 22 via a line 46. The speed sensors 3.8 and 40 generate signals which represent the speeds of the vehicle wheels 14 and 16, respectively, and these Signals arrive via lines 44 and 46 as input signals to the next control step 22. '-

The main control stage 20 is of the usual design and is used to to modulate the brake pressure supplied to the rear wheel brakes 10b, 12b by the master cylinder 18, if via the speed sensor 36 an impending slip condition on the rear wheel set is determined. If the speed sensor 36 of the main control stage 20 The mean value speed signal supplied changes in such a way that an impending slip condition on the rear wheels is indicated is, the main control stage 20 actuates the modulator 24, whereby

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the brake pressure at the rear wheels 10 and 12 is modulated and thereby prevents locking of the rear wheels and subsequent slipping of the rear wheels during the braking process will. Blocking regulation * for regulating the brakes IGb and 12b are in U.S. Patent 3,578,819, U.S. Patent Aimeldüng 193,393, dated October 28, 1971 and US patent application 761 04-5 of September 20, 1968. One trained in the manner described there Main control stage 20; modulates the brake pressure for the rear wheels such; that with a selected wheel deceleration a brake pressure relief and stoking at a selected wheel acceleration a renewed printout takes place. That way will a desired blocking regulation for changing Eahrbalmstatus achieved.

According to one embodiment of the invention, the front-wheel brakes 14b and 16b are readjusted to the rear wheels 10 and 12 after a previous control stage of the rear wheels has been determined in the main control stage 20. For this purpose, the next control stage 22 is connected to the main control stage 20 via a line 48 . ' Hächdem DIE Hauptrögelstufe '20 eineii forthcoming Rut has schzuständ determined to Hiriterrääerri, it provides ^v eih signal via the Leituiig 48 äl§ Eihgäiifssignäl to MChS control stage'2'ii Üieses signal känii two '' Ch ^'giicn: i represent functions: on the one hand / the miitl έ ± '&' speed of the Hiirtferfa-. der 10.1 2j \ die ^ 'Vom Brehziahigeblr ^; - "3" 6 ^ rmitte'li uhä "through" a signal converter in the * head ^ rule stage i 20 converted iSuf de ^ at-

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for example a digital-to-analog converter; or a desired one Reference speed that is supplied by the main control stage .20 will. This signal is used as the relevant vehicle reference speed is used against which the speed of the front wheels is measured. '

The next control stage 22 also couples the front wheels 14 and 16 the rear wheels 10 and 12 by comparing the speeds of the front wheels with the signal supplied by the main control stage 20 will. One way of getting the speed information from each front wheel speed sensor To compare in the readjustment stage 22 with the signal from the main control stage 20 consists in the mean value determine the speed of the front wheels and then this mean value speed signal. the front wheels with the Compare the signal of the main control stage 20. In this case, the readjustment stage 22 can operate the modulator 26 such that a desired slip is maintained between the front and rear wheels during lock-controlled braking. As soon as an impending slip condition on the rear wheels has thus been determined, the rear wheels 10 and 12 are via the main control stage 20 block! Is regulated, while the blocking regulation of the Front wheels 14 and 16 takes place in that these are the rear wheels 10,12 can be readjusted.

Fig. 2 shows a more specific arrangement for coupling the ' Front wheels 14,16 to the rear wheels 10,12..DXe; of the turning

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Signals generated by counter 38, 40 are signal converters 50. or 52 supplied, for example digital-to-analog converters. Everyone Signal converter supplies a direct current output voltage, the size of which represents half the speed of the assigned vehicle wheel. The output voltages of the transducers 50 and 52 become via lines 54 and 56 as input signals of a summing stage 58 supplied. A DC reference voltage 60 comes across a line 62 as a third input signal to the summing stage 58-. The summing stage 58 adds these three input signals and delivers an output signal representing the mean speed of the Front wheels 14 and 16, but changed by one of the DC reference voltage 60 corresponding speed represents.

The output of summing stage 58 is over a line 64 to one input of a subtraction stage 66. The line 48 * from the main control stage 20 is to the other input of the sub, traction stage 66 connected and provides an average speed signal the rear wheels. The subtraction stage 66 determines the difference between these two signals and delivers an output signal representing this difference. This Output signal narrowed via a line 66 as an input signal to a monostable pulsator 70.

The monostable pulsator 70 repeatedly generates an output pulse, as long as the input signal exceeds a specified value. In the exemplary embodiment shown, the

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Pulsator 70 provides a uniform output pulse as long as the mean rear wheel speed exceeds the mean front wheel speed by an amount greater than that is the slip set via the reference voltage 60. Palis, for example the reference voltage 60 represents a slip of 6 km / h, the front wheel brakes are only modulated during the lock control if the average front wheel speed is at least 6 km / h less than the mean rear wheel speed. There is an advantage to this embodiment of the invention in that the slip represented by the reference voltage 60 can be changed in a simple manner only by adjustment the level of the reference voltage can be changed; In this way, the locking control of the front wheels by coupling to the Lock control of the rear wheels take place and an optimal overall control can be achieved.

The output signal of the pulsator 70 is transmitted via a line 72 to the front wheel brake pressure modulator 26, which according to Pig. 2 of separate modulation stages 26a and 26b for each brake 14b, 16b consists, the switching coils are connected in series. Each modulation stage 26a, 26b is an "on-off" device which is switched on when its switching coil is energized and switched off when its switching coil is de-energized. The from the pulsator 70 den Actuate the output pulses supplied to the modulation stages 26a and 26b the switching coils of the modulation stages, however, in such a way that that the brake pressure is relieved to the extent that this is the number of pulses from the pulsator 70 during a period of time under consideration

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generated pulses corresponds. By such a -tended. Pulse modulation, maximum pressure relief is achieved when the pulsator 70 generates a continuous series of pulses, and the pressure relief diminishes as the pulsator 70 increases is switched on intermittently. Through intermittent excitation of the switching coils of the modulation stages thus becomes essentially one with the help of an "on-off" modulator proportional modulation achieved. "Different types of modulators can be used, for example hydraulic, air or vacuum operated. In addition, a modulator can be provided for each individual wheel or for each wheel set and in the first "case, the modulators can either be in series or be connected in parallel to the pulsator 70 ,.

In the embodiment according to Pig. 3, with the same components are identified by the same reference numerals, are Speed sensors 38 and 40 via lines 44 and 46 to the inputs, a summing and "amplifier stage 80 is connected, which has an output signal that is the average speed of the front wheels 14 and 16 represents. The output signal of stage 80 has been reached via a line 82 to an input of a subtraction stage 84. The output of the main control stage 20 is not on the in FIGS. 1 and 2 to the readjustment device connected for the front wheels, but the line 42 leads from the speed sensor 36 both to the main control stage 20 "and to an average and amplifier stage 86. The main control stage provides for a locking control of the rear wheels 10 and 12 on the

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way described above. The front wheel brakes are coupled to the rear wheels by connecting the output of the Average value and amplifier stage 86 via a line 88 to the other input of the subtraction stage 84. The stage 86 converts the signal supplied by the speed sensor 36 and gives to the subtraction stage 84 a speed signal, which is a smoothed Represents the speed curve of the rear wheels 10,12. The subtraction level 84 compares this signal with the average speed signal of the front wheels and delivers a Line 90 sends a signal to the modulation device 26 for modulating the front wheel brakes when the average front wheel speed drops below the rear wheel speed represented by the aforementioned speed curve signal. The embodiment according to Pig. 3 differs thus different from the embodiments described above in that the front wheel speed signal is constantly synchronized with the rear wheel speed signal is compared, while according to FIGS. 1 and 2 the front wheel speed signal with the rear wheel speed signal is only compared if an impending slip condition on the rear wheels is determined became. In the anti-lock braking system according to Pig. 3, thus the Front wheels not only readjusted to the rear wheels when an impending slip condition on the rear wheels is determined, but a predetermined slip of the front wheels is also determined against the 'rear wheels, so that the front brakes be modulated even when blocking

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the rear wheels is not yet imminent. To make this system fail-safe to train, a shutdown device 'is preferably provided for shutting down the entire locking control, if either the rear wheel brake pressure fails or the locking control for the rear wheels is disturbed in such a way that the rear wheels lock up. .

In the exemplary embodiment according to FIG. 4, the rear wheels 10, 12 are readjusted to the front wheels 14, 16. The front wheels 14,16 A blocking controller 92 is assigned, and speed sensors 38, 40 are connected to the inputs of the blocking controller via lines 44 and 46, respectively 92 connected. One possibility for locking control of the wheels 14, 16 by the locking controller 92 is when Occurrence of an impending slip condition on any of the front wheels to modulate the front wheel brakes 14b and 16b via the modulator 26. The speed sensors 38 and 4.0 are also connected to the inputs of an upper value selection circuit 94. The selection circuit 94 determines the slower rotating front wheel and generates an output signal that represents the speed of the faster represents running front wheel.

One possibility for a corresponding design of the selection circuit 94 is to convert the signal generated by the speed sensors 38 and 40 into a direct current signal which represents the speed of the corresponding front wheel. These DC signals are compared in a comparison stage with ^:

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compared to each other, which fades out the smaller signal and only lets the larger signal through.

The one representing the speed of the faster turning vehicle wheel The signal is in turn fed to the input of an average and amplifier stage 98 via a line 96. The mean and amplifier stage 98 operates in the same way as stage 86 of FIG. 3 and supplies via line 100 Signal to one input of a subtraction stage 102. This signal represents the average front wheel speed, the the rear wheels can be readjusted. The rear wheel speed sensor 36 is connected to the input of a signal converter 104 via a line 42. The signal converter 104 corresponds to Signal converters 50 and 52 according to Pig. 2 and provides an output signal via the line 106 to the second input of the subtraction stage 102. The output signal of the subtraction stage 102 arrives via a line 108 to the brake pressure modulator 24 * so that the Rear brakes are modulated when the speed of the rear wheels is a specified slip below the speed the front wheels fall off. The anti-lock braking system according to FIG. 4 thus essentially works with respect to the rear wheels works in the same way as the anti-lock braking system according to FIG. 3 with respect to the front wheels, since not only the rear wheels the front wheels are readjusted if an impending slip condition is determined on one of the front wheels, but even if a given slip on the rear wheels with respect to

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of the faster rotating front wheel is determined, so that the Rear wheel brakes are modulated even if the front wheels are not in a slip condition.

An advantage of the embodiments of the invention described above is that effective four-wheel lock-up control is achieved with a marked reduction in the number of components required is achieved. According to the invention, one wheel set is locked-up controlled, while the other wheel set is fully lock-controlled Wheelset is readjusted. Since the circuit required for the readjustment device is considerably simpler than that for a full blocking control is required circuit results a significant reduction in overall construction costs and however, desirable four-wheel stall control is achieved.

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Claims (1)

Patent Attorneys "-. ^ Dr. Ing. H. Negendank Dipl. Inc. H. Haück - Din? Phy ». VV. Schmitt Dipl. Ing. E. Graalfs - Dipl. Ing. W. Wehnert . . . 8 Munich 2, Mozerf Strasse 25. Kelsey-Hayes Company Telephone 5380586 38481 Huron River Drive
Romulus, Mich. 48174, USA December 14, 1973 Attorney File M-2889 Claims 1.) Anti-lock braking system for a wheeled vehicle with separate Fluid brake circuits for the front and rear wheel sets, characterized by the combination of the following features: a first speed sensor (36; 38, 40) assigned to one wheel set (10, 12; 14, 16) for generating a first, a predetermined speed characteristic of the speed signal representing a wheel set, a first lock controller (20, 24; 26, 92), including one, connected to the first speed sensor an impending slip condition aa the one wheel set (10,12; 14,16} responsive, first modulation device (20; 26) for modulating the fluid pressure in -15-409825 / 0903 . - 15 - . the brake circuit assigned to a wheelset, a mild first speed sensor ("36; 38, 40) coupled Circuit including a signal device (86; 94, 98) responsive to an impending slip condition on the wheel set for generating a a desired speed characteristic for readjustment of the other wheelset (14 * 16; 10,12) representing the reference signal, and a second lockout regulator (22,26,38,40,44 to 90; 24,36,42,102 to 108) for the other wheelset including a post-control stage (38, 40, 44 to 72, 84, 88, 90; 36, 42, 104, 106, 108) to control the other gear set as a function from the reference signal, yes with a second speed sensor (38, 40; 36) for generating a second speed signal assigned to the other wheel set, a comparison stage (22,66,841 102) for comparing the second speed signal with the reference signal and a second Modulation device (26; 2.4) for modulating the fluid pressure in the brake circuit assigned to the other wheelset when a predetermined deviation is exceeded of the second speed signal from the reference signal. 2. Anti-lock braking system according to claim 1, characterized in that the first speed sensor (36) has a mean value sensor for Determination of the mean speed of the wheels of the 409825/0903 has a set of wheels (10, 12). 3. Anti-lock braking system according to claim 1 or 2, characterized in that that the signal device (86; 94, 98) has a signal stage which, when an impending Slipping state of the one wheel set (10, 12; 14, 16) when the one wheel set is braked in a lock-controlled manner derived from a speed characteristic of one of the wheelsets Delay reference signal generated. 4. Anti-lock braking system according to claim 1, characterized in that the signal device (86; 94, 98) has a signal stage for generating the reference signal as a function of the has the first speed signal generated by the first speed sensor (36; 38, 40). 5. Anti-lock braking system according to one of the preceding claims, characterized in that the first speed sensor (38, 40) a switching stage (94) for determining the speed of the faster rotating wheel of the one wheel set, which generates a signal representing the speed of the faster rotating wheel as the first speed signal (Pig. 4). 6. Anti-lock braking system according to claim 5, characterized in that the one set of wheels are the vehicle front wheels (14, 16) ig. 4). 409825/0903 ?. Anti-lock braking system. Claim 1, characterized in that that the second speed sensor (38, 40) has an average value stage (58, 80) for averaging the wheel speeds of the other Wheelset (14, 16), the second speed ssignal a the mean wheel speed of the other wheelset Representative mean value signal generated. » 8. Antiblockiersystemhach claim 7, characterized by a signal converter (60) which changes the mean value signal by a predetermined amount. - 9. Anti-lock braking system according to one of the preceding claims, characterized in that the second modulation device (26) a modulator (26a, 26b) and a pulse generator (70) which the modulator when a 'predetermined difference between the second speed signal is exceeded and the reference signal operated pulsating (Pig. 2). 10. Anti-lock braking system according to claim 9, characterized in that that the pulse generator (70) contains a monostable pulsator. Ί1. Motor vehicle anti-lock braking system for locking control un-, independently braked front and rear wheel sets, -18- 40982 5/0903 characterized by the combination of the following features: a blocking regulator assigned to one of the wheelsets (10, 12; 14, 16) (20,24,36; 26,38,40,92) including a first speed monitor assigned to one wheel set (36; 38, 40) for generating a selected speed characteristic of the first speed signal representing a wheel set, one to the first speed sensor connected blocking control stage (2Oj 92) and one connected to the blocking control stage, first modulation device (20; 26) for modulating the brake pressure supplied to the brakes of one wheel set, wherein the blocking regulator (20,24,36; 26,38,40,92) as a function of of a predetermined change of the indicating an impending slip condition on a wheelset first speed signal can be actuated and a speed characteristic for readjustment of the other wheelset (14,16; 10,12) generated next control signal representing, and a readjustment device (22, 26, 38, 40; 44 to 72; 84 to 90; 24, 36, 42, 94 to 108) for coupling the other Wheel set to the one wheel set, with a second, the other wheel set associated speed sensor (38,40; 36) for Generation of a second, selected speed characteristic the speed signal representing the other wheelset, one to the second speed sensor -19- 409825/0903 V -: '- 19- connected next control stage (22, 50 to 70, 84,88, · 90j 94 to 106), a second, to the next control stage connected modulation device (26j 24) for modulation the one fed to the brakes of the other wheelset, Brake pressure and a switching connection (48,86) between the blocking regulator (20,24 ^ 36S 26,58,40,92) and the adjustment stage (22.50 to 7p, 84, 88, .90; 94 to 106) for Transfer of the readjustment signal to the next control stage, by the readjustment signal supplied to the next stage in the event of a specified deviation of the von'Blocking Controller * si from the speed signal of the second RPM. · Encoder modulates the brakes of the other wheelset supplied brake pressure can be switched on. 12. Anti-lock braking system according to claim 1.1, characterized in that that the readjustment signal represents the average speed of a wheel set (10,12} 14,16). 13. Anti-lock braking system according to claim 11 or 12, characterized in that that one set of wheels is the rear of the vehicle = · wheels (10, 12). and the other the vehicle front wheels (14,16) are. . 14. Anti-lock braking system according to claim 11 ₉ characterized gekeniizeich- * net that the readjustment signal represents the speed of the faster rotating wheel of a wheel set (Pig.4) • '-20- 4 0 9825/0903 15. Anti-lock braking system according to claim 14, characterized in that that one set of wheels is the vehicle's front wheels (14,16) and the other is the vehicle's rear wheels (10,12) (Fig. 4). 16. Anti-lock braking system according to one of claims 11 to 15, characterized characterized in that the second modulation device (26) a modulator (26a, 26b) and a pulse generator (70) has that the modulator is exceeded when a predetermined • given difference between the readjustment signal and the speed signal of the second speed sensor (38, 40) operated in a pulsating manner (Fig. 2). 17. Anti-lock braking system according to claim 16, characterized in that that the pulse generator (70) contains a monostable pulsator (Fig. 2). 409825/0 9 03 L e r soap