US3874741A — Wheel brake antilock system with noise signal rej…

Claim 1

Independent Claim 254 words

Fluid brake vehicle antilock system having a wheel brake cylinder, electrically operated and controlled fluid inlet and outlet valve means (14, 19), means (30, 31, 32, 33) sensing acceleration of the wheels of the vehicle and including a differentiator (33), threshold switch means including first, second and third threshold switches (35, 36, 37) connected to said acceleration sensing means and responding upon predetermined sensed rates of change of wheel speed, and a logic network connected to said threshold switches selectively controlling the energization of the electrically controlled fluid inlet and outlet valve means to command pressure rise, constant pressure and pressure drop in the wheel brake cylinder; wherein said acceleration sensing means includes a first low pass filter means (32) connected in advance of the input of the differentiator (33); a second low pass filter means (34) connected behind the output of the differentiator (33); and conjunctive means (42) controlling the electrical control of the outlet valve means (19), said conjunctive means having one input connected to the first threshold switch (35) and another input connected to the second threshold switch (36), said first threshold switch having its input connected to the differentiating means through the second low pass filter means (34) and said second threshold switch (36) having its input connected to the differentiator (33) directly; the third threshold switch (37) being connected to the output of the second low pass filter means (34); and means (45) disjunctively connecting the inlet valve means (14) and the first and third threshold switches (35, 37).

Claim 2

Dependent Claim 254 words

Fluid brake vehicle antilock system having a wheel brake cylinder, electrically operated and controlled fluid inlet and outlet valve means (14, 19), means (30, 31, 32, 33) sensing acceleration of the wheels of the vehicle and including a differentiator (33), threshold switch means including first, second and third threshold switches (35, 36, 37) connected to said acceleration sensing means and responding upon predetermined sensed rates of change of wheel speed, and a logic network connected to said threshold switches selectively controlling the energization of the electrically controlled fluid inlet and outlet valve means to command pressure rise, constant pressure and pressure drop in the wheel brake cylinder; wherein said acceleration sensing means includes a first low pass filter means (32) connected in advance of the input of the differentiator (33); a second low pass filter means (34) connected behind the output of the differentiator (33); and conjunctive means (42) controlling the electrical control of the outlet valve means (19), said conjunctive means having one input connected to the first threshold switch (35) and another input connected to the second threshold switch (36), said first threshold switch having its input connected to the differentiating means through the second low pass filter means (34) and said second threshold switch (36) having its input connected to the differentiator (33) directly; the third threshold switch (37) being connected to the output of the second low pass filter means (34); and means (45) disjunctively connecting the inlet valve means (14) and the first and third threshold switches (35, 37).

Claim 3

Dependent Claim 24 words

System according to claim 1 further comprising an interlock connected between the electrical connection of said outlet valve and said disjunctive connection means (45).

Claim 4

Dependent Claim 41 words

System according to claim 1 further comprising a speed comparison stage (41) comparing individual wheel speeds with vehicle speed; and means (44) disjunctively controlling the outlet, or drain valve (19) from said conjunctive means (42) or said speed comparison stage (41).

Claim 5

Dependent Claim 36 words

System according to claim 3 wherein the speed comparison stage comprises a comparator circuit having applied as one input a signal representative of wheel speed and as another input a signal representative of simulated vehicle speed.

Claim 6

Dependent Claim 55 words

System according to claim 3 further comprising conjunctive means (43) having its output connected to said disjunctive control means (44) for the outlet or drain valve (19), the conjunctive means (43) having one input connected to the speed comparison stage (41) and another input connected to a third threshold switch (37) of said threshold switches.

Claim 7

Dependent Claim 49 words

System according to claim 1 wherein the first threshold switch (35) includes threshold shift means having a threshold shift input (V) shifting the threshold response level thereof; and a differentiator circuit (567, 568, 569) is provided, connecting the output of the third threshold switch with said shift input (V).

Claim 8

Dependent Claim 83 words

System according to claim 1 wherein said threshold switches comprise a fourth threshold switch (38) having a threshold response level responding to high positive wheel acceleration, said fourth threshold switch being connected to the output of the differentiator (33); and an AND gate (50) is provided, connected in advance of the electrical connection to the inlet valve (14), said AND gate having its input connected to the output of the fourth threshold switch (38) and the output of the disjunctive connection means (45).

Claim 9

Dependent Claim 81 words

System according to claim 1 further comprising a bistable flip-flop (FF) (46) forming a control memory, said bistable FF having a set input (S) connected to the output of the first threshold switch (35); a pulse source (47) is provided having a blocking input (E), the output of the bistable FF (46) being connected to the blocking input (E) of the pulse source, the output of the pulse source being connected to the electrical connection for the inlet control valve (14).

Claim 10

Dependent Claim 121 words

System according to claim 8 wherein the threshold switches comprise a third threshold switch (37) connected to the output of the second low pass filter (34), said third threshold switch (37) includes a circuit shifting the threshold response level thereof, and having a threshold shift terminal (V) which, upon energization, shifts the threshold response level; said first threshold switch (35) includes a circuit shifting the threshold response level thereof and having a threshold shift terminal (V) which, upon energization thereof, shifts the threshold response level; and wherein the output of the bistable FF (46) is connected with the threshold shift input (V) of the third threshold switch (37) and with the threshold shift terminal (VI) of the first threshold switch (35).

Claim 11

Dependent Claim 83 words

System according to claim 9 wherein the second threshold switch (36) includes a circuit shifting the threshold level thereof and having a threshold shift terminal (V) which, upon energization, shifts the threshold level of the second threshold switch (36), to distinguish between different road conditions; a timing circuit (48) is provided, the output of the first threshold switch (35) being connected to the timing circuit (48) which has its output connected to the threshold shift input (V) of the second threshold switch (36).

Claim 12

Dependent Claim 115 words

System according to claim 10 wherein the circuit shifting the threshold response level of the first threshold switch (35) has two inputs (V1, V2) and shifting the threshold response level by different values, the second threshold shift terminal (V2) shifting the threshold level by a higher value than said first input, in order to suppress error signals due to oscillation of the suspension of the vehicle; a second timing circuit (49) is provided, said second timing circuit being controlled by the output of the first threshold switch (37) and having its output connected to the second threshold shift terminal (V2) of the first threshold switch to shift the threshold level during the timing period thereof.

Claim 13

Dependent Claim 66 words

System according to claim 8 wherein the bistable FF has a reset terminal (R), a reset control stage (61) is provided, said reset control stage including a timing circuit; the vehicle has a brake light switch (28, 29), and a series circuit comprising a diode (63) and a resistor (64) connecting the brake light switch (28, 29) to the input of the reset control stage (61).

Claim 14

Dependent Claim 55 words

System according to claim 12 wherein only a single reset control stage (61) is provided for all brake antilock systems in the vehicle, said single reset control stage having its output connected to the reset terminals of all bistable FFs (46, 461, 462) associated with individual control systems of the individual axles of the vehicle.

Claim 15

Dependent Claim 61 words

System according to claim 13 wherein the threshold switches associated with the axles of the vehicle comprise a third threshold switch (37) connected to the output of the second low pass filter (34) of each individual control system; and resistance means (68) connecting the outputs of all the third threshold switches (37) to the input of the reset control circuit (61).

Claim 16

Dependent Claim 43 words

System according to claim 13 comprising a capacitor (72) coupled to the outputs of the first threshold switches (35) of the antilock control systems associated with individual vehicle axles, the capacitor (72) being connected to the input of the reset control circuit (61).

Claim 17

Dependent Claim 52 words

System according to claim 12 wherein the diode (63) is so poled that the output of the reset control circuit (61) is short circuited when the brake is not operated, the reset control circuit (61) providing a reset signal to the bistable FFs (46, 461, 462) upon short circuiting of its input.

Claim 18

Dependent Claim 73 words

System according to claim 1 further comprising a speed comparison stage (41) comparing individual wheel speeds and vehicle speeds, said speed comparison stage comprising an operational amplifier (410) having a resistor (411) in its feedback circuit to operate as a threshold switch; said operational amplifier having two inputs, one input having applied thereto a signal representative of wheel speed, and the other input having applied thereto a signal representative of simulated vehicle speed.

Claim 19

Dependent Claim 71 words

System according to claim 1 wherein a vehicle speed simulation stage (40) is provided, to provide an output signal representative of vehicle speed, comprising a storage capacitor (400), a constant current source (405, 406, 407, 408) loading said storage capacitor; a group of diodes (401, 402, 403, 404), and means connecting signals representative of wheel speed to the diodes, the outputs of said diodes being connected to the storage capacitor (400).

Claim 20

Dependent Claim 57 words

System according to claim 18 further comprising a speed comparison stage (41) comparing individual wheel speeds and vehicle speed, said speed comparison stage comprising a comparator circuit having applied thereto the outputs of said diodes (401 to 404), and having a threshold level which is determined by the unblocking threshold voltage of the diodes (401 to 404).

Claim 21

Dependent Claim 101 words

System according to claim 1 further comprising two timing circuits (53, 55) serially connected to the output from the first threshold switch (35); wherein said first threshold switch includes a circuit shifting the threshold response level thereof and having a threshold shift terminal (V) which, upon energization, shifts the threshold response level of said threshold switch (35); and wherein a connection circuit is provided from the output of the second serially connected timing circuit (55) to the threshold shift terminal (V) of said first threshold switch, said connection circuit comprises a parallel connection of a resistor (566) and a capacitor (567).

Claim 22

Dependent Claim 104 words

System according to claim 20 wherein the normal threshold level of the first threshold switch is set at about -2.5g; the first timing circuit providing a delay time (T1) of about 5 milliseconds; the second timing circuit (55) providing a delay time (T2) of about 50 milliseconds; and the threshold shift circuit of the first threshold switch (35) is set to change the threshold response level of the first threshold switch to the value of -3.5g about 5 milliseconds after first response of the first threshold switch and for the time duration (T2) of the operation of the second timing circuit (55) (FIG. 5).

Claim 23

Dependent Claim 39 words

System according to claim 1 wherein the first low pass filter means (32) has a band pass widths of about 45 Hz, and said second low pass filter means (34) has a band pass widths of about 8 Hz.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1978-03-31	1978-09-30	1979-04-01	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1982-03-31	1982-09-30	1983-04-01	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1986-03-31	1986-09-30	1987-04-01	$7700.00	Window Closed / Lapsed

Wheel brake antilock system with noise signal rejection circuit

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