Circuit for influencing the brake-pressure release and/or brake-pressure holding phases for antilocking vehicle brake systems

• US 4,270,810 A
• Filed: 04/23/1979
• Issued: 06/02/1981
• Est. Priority Date: 04/29/1978
• Status: Expired due to Term

• Current Assignee: Wabco Westinghouse Fahrzeugbremsen GmbH
• Original Assignee: Wabco Westinghouse Fahrzeugbremsen GmbH
• Inventors: Ruhnau, Gerhard, Lindemann, Klaus, Gudat, Wolfgang, Saba, Manfred
• Primary Examiner(s): Miller, J. D.
• Assistant Examiner(s): EISENZOPF, REINHARD
• Application Number:
  US06/032,571
• Time in Patent Office: 771 Days
• Field of Search: 303/106, 303/105, 303/110, 303/91, 303/20
• US Class Current: 303/184
• CPC Class Codes: B60T 8/173 Eliminating or reducing the effect of unwanted signals, e.g. due to vibrations or electrical noise

Abstract

A circuit arrangement for influencing the brake pressure venting phase and/or brake pressure retaining phase for an antiskid vehicle braking system when the measured velocity difference deviates from a given velocity difference during controlled braking. The velocity change is determined as a function of the wheel tendency or tendencies by measuring and differentiating the velocity value or values at the interval boundaries of an assigned time Δt of the control signals or by the assigned times of the control signals. A switching circuit, to which the brake pressure control signals, such as, the acceleration +b, deceleration -b and slip λ control signals, and a signal representing the wheel tendencies, such as, either positive or negative velocity change of the sensed wheel or wheels, can be set upon drop away of a +b or -b signal. The switching circuit controls a shifting circuit which changes the assigned time Δt or some or all assigned times Δt or changes the switching times of the control signals as a function of the signal or signals indicating the wheel tendency or tendencies. Thus, the shifting circuit produces a high signal, a medium signal, or a low signal indication representing an appropriate assigned time Δt.

Claims

1. A switching circuit arrangement for controlling the brake pressure exhausting phase and brake pressure holding phase for antiskid vehicle braking apparatus when the measured velocity change differs from a given velocity change during controlled braking wherein the velocity change is obtained by measuring and forming different velocity values at the intervening limits of an assigned time Δ

t, characterized by, switching means having a plurality of inputs for accommodating acceleration and deceleration control signals as well as a signal representing the starting tendency signal of a monitored wheel of the vehicle, and bidirectional shift register means responsive to the switching means for establishing the assigned time Δ

t dependent upon the particulars of the acceleration and deceleration control signals and as a function of the wheel tendency signal.

2. The switching circuit arrangement according to claim 1, wherein said shift register means causes a shorter assigned time Δ

t when a deceleration control signal disappears and a positive tendency is exhibited by the monitored wheel.

3. A switching circuit arrangement according to claim 1, wherein said shift register means causes an increase in the assigned time Δ

t when another deceleration control signal occurs before the occurrence of an acceleration control signal.

4. A switching circuit arrangement according to claim 1, wherein said shift register means fails to change the assigned time Δ

t when a deceleration control signal ceases during the presence of a negative wheel tendency signal as well as when an acceleration control signal ceases during the presence of a positive wheel tendency signal in the event no other like deceleration or acceleration control signal has appeared without the prior appearance of an unlike acceleration or deceleration control signal.

5. A switching circuit arrangement according to claim 1, wherein said shift register means is a shift register having a plurality of stages, each of which is representative of a different assigned time Δ

t.

6. A switching circuit arrangement according to claim 5, wherein said shift register is capable of being shifted in both a left-hand and right-hand direction.

7. A switching circuit arrangement according to claim 5, wherein said switching means is a logic circuit which logically connects the acceleration, deceleration and slip control signals with each other and also with the signal indicating the wheel tendency, and controls the shift register in accordance with the connections.

8. A switching circuit arrangement according to claim 7, wherein said logic circuit includes a first AND gate for accommodating the deceleration control signal and the wheel tendency signal, a second AND gate for accommodating a deceleration control signal which is negated by an inverter along with the acceleration control signal, a data flip-flop having a reset input which is connected with the output of said second AND gate, having a clock input which is connected to the output of said inverter, and having a data input which is supplied with a positive potential, a third AND gate for accommodating the output of said flip-flop along with the deceleration control signal, an OR gate having its input connected with the outputs of said first and third AND gates, and a time element device connected to the output of said OR gate for providing a delayed signal.

9. A switching circuit arrangement according to claim 8, wherein said shift register includes a first data flip-flop and a second data flip-flop, OR gate connected to the output of said first flip-flop and to the output of said second flip-flop, the output of said first OR gate of said shift register and the output of said third AND gate of said logic circuit is connected to a first AND gate of said shift register, the output of said first AND gate of said shift register is connected to the data input of said second flip-flop, the output of the second flip-flop and a negated output of said first AND gate of the logic circuit is connected to a second AND gate of said shift register, the output of said first AND gate of said logic circuit and the output signal of said first OR gate which is negated by an inverter is connected to a third AND gate of said shift register, the negated output of said inverter and the output of said second AND gate is connected to a second OR gate, the output of said second OR gate is connected to the data input of first flip-flop (2), and the clock inputs of said first and second data flip-flops are connected to the output of the time element.

10. A switching circuit arrangement according to claim 9, wherein the output of said inverter of said shift register and the outputs of said first and second data flip-flops of said shift register are assigned to different assigned times.

11. A switching circuit arrangement for controlling the brake pressure exhausting phase and brake pressure holding phase for antiskid vehicle braking apparatus when the measured velocity change differs from a given velocity change during controlled braking wherein the velocity change is obtained by measuring and forming different velocity values, characterized by, switching means having a plurality of inputs for accommodating acceleration, deceleration and slip control signal for causing an increase in the switching time of the slip control signal when the acceleration control signal reappears during the presence of a slip control signal without prior appearance of a deceleration control signal, and said switching means includes a first data flip-flop and second data flip-flop, the clock inputs of said first and second flip-flops are supplied with the acceleration control signal, the reset inputs of said first and second flip-flops are supplied with the deceleration control, the data input of the first flip-flop is connectable to a positive potential, the output of the first flip-flop is connected with the data input of the second flip-flop, the output of said second flip-flop is negated, the output of said second flip-flop and the acceleration control signal are connected to a first AND gate, the output signal of said first AND gate is connected to a negated input of a second AND gate while the acceleration control signal is connected to another input of said second AND gate, the output signal of said second AND gate and the deceleration signal are coupled to an exhaust valve via a first OR gate, while acceleration, deceleration and slip control signals are coupled to an input valve via a second OR gate.

12. A switching circuit arrangement for controlling the brake pressure exhausting phase and brake pressure holding phase for antiskid vehicle braking apparatus when the measured velocity change differs from a given velocity change during controlled braking wherein the velocity change is obtained by measuring and forming different velocity values, characterized by, switching means having a plurality of inputs for accommodating acceleration, deceleration and slip control signals for causing a reduction in the value of threshold slip of a slip threshold switching circuit during a time when the acceleration control signal ceases after the slip control signal ceases, and said switching means includes a time delay element having its input coupled to the acceleration control signal, the output of said time delay element is connected to one input of an AND gate and the acceleration control signal is connected to a negated input of said AND gate, and the output of said AND gate is conveyed to a threshold value stage.

13. A switching circuit arrangement for controlling the brake pressure exhausting phase and brake pressure holding phase for antiskid vehicle braking apparatus when the measured velocity change differs from a given velocity change during controlled braking wherein the velocity change is obtained by measuring and forming different velocity values, characterized by, switching means having a plurality of inputs for accommodating acceleration, deceleration and slip control signals for causing an increase in the switching time of the slip control signal when the slip control signal is still present when the acceleration control signal ceases, and said switching means includes a data flip-flop having its data input supplied by a slip control signal and having its clock input supplied with an acceleration control signal, said flip-flop is clocked when an acceleration control signal drops away and a deceleration control signal is applied to the reset input of said flip-flop, and the output of said flip-flop is connected to the clock input of a monostable multivibrator, which provides an output to energize an intake valve and an exhaust valve.

14. A switching circuit arrangement for controlling the brake pressure exhausting phase and brake pressure holding phase for antiskid vehicle braking apparatus when the measured velocity change differs from a given velocity change during controlled braking wherein the velocity change is obtained by measuring and forming different velocity values characterized by, switching means having a plurality of inputs for accommodating acceleration and deceleration control signals for causing an increase in switching time of the acceleration control signal when the acceleration control signal reappears without prior appearance of a deceleration control signal, and said switching means includes a first data flip-flop and a second data flip-flop, the clock inputs of said first and second data flip-flops are supplied with an acceleration control signal, the reset inputs of the first and second data flip-flops are supplied with a deceleration control signal, the data input of said first flip-flop is connected to a positive potential, the output of the first flip-flop is connected to the data input of said second flip-flop, the acceleration control signal is connected to a time delay element, the output of said second flip-flop and the output of said time delay element are connected to an AND gate, and the output signal of the AND gate and the acceleration control signal are connected to inputs of an OR gate, the output of said OR gate is rendered an effective acceleration control signal.

15. A switching circuit arrangement for controlling the brake pressure exhausting phase and brake pressure holding phase for antiskid vehicle braking apparatus when the measured velocity change differs from a given velocity change during controlled braking wherein the velocity change is obtained by measuring and forming different velocity values characterized by, switching means having a plurality of inputs for accommodating acceleration and deceleration control signals for causing an increase in the switching time of the acceleration control signal when a low coefficient of friction has been detected, said switching means includes a data flip-flop having its clock input fed with an acceleration control signal, said flip-flop having its reset input fed with a deceleration control signal and having its data input connected to a positive potential, the output of said flip-flop and the acceleration control signal are connected to an AND gate, the output of said AND gate is connected by a time delay element, the output signal of the time delay element and the acceleration control signal are connected to the inputs of an OR gate (92) so that the output signal of the OR gate is rendered an effective acceleration control signal.