Electric control device for an automotive brake system

• US 3,902,763 A
• Filed: 07/09/1974
• Issued: 09/02/1975
• Est. Priority Date: 07/11/1973
• Status: Expired due to Term

• Current Assignee: Yasuhisa Takeuchi
• Original Assignee: Yasuhisa Takeuchi
• Inventors: Takeuchi, Yasuhisa
• Primary Examiner(s): Blix, Trygve M.
• Assistant Examiner(s): Kunin, Stephen G.
• Application Number:
  US05/486,853
• Time in Patent Office: 420 Days
• Field of Search: 188/181 303/20,21 307/1R 317/5 324/161-162 340/53,62,262-263
• US Class Current: 303/193
• CPC Class Codes: B60T 8/17613 based on analogue circuits or digital circuits comprised of discrete electronic elements

Abstract

An electric control device for use with an automotive brake system including a hydraulic actuator unit to control the braking force during braking, especially when an impending skid condition is detected, characterized in that a signal to reduce the braking force are a signal to thereafter increase the braking force and issued at timings which are earlier than those usually prescribed in prior art control devices so that the delay time involved in the operation of the actuator unit can be compensated for.

Claims

1. An electric control device for an automotive brake system having skid control means, comprising a vehicle speed sensor for detecting a speed of an automotive vehicle and producing an output voltage proportional to the detected vehicle speed, a wheel speed sensor for detecting a circumferential speed of rotation of a road wheel of the vehicle and producing an output voltage which is proportional to the detected wheel speed, computing means for subtracting from the output voltage of the vehicle speed sensor a first variable reference voltage which is related to and smaller than the output voltage of the vehicle speed sensor and producing an output voltage proportional to a difference between the two voltages, first comparing means for comparing the output voltage of the computing means with the output voltage of the wheel speed sensor and producing a first control signal when the former is higher than the latter, second comparing means for comparing the output voltage of the computing means with a second variable reference voltage related to and smaller than the output voltage of the wheel speed sensor and producing a second control signal when the former is higher than the latter, first differentiating means for differentiating the output voltage of the wheel speed sensor with respect to time and producing an output signal proportional to a rate of increase of the output voltage of the wheel speed sensor, third comparing means for comparing the output voltage of the first differentiating means with a first constant reference voltage and producing a third control signal when the former is higher than the latter, second differentiating means for differentiating the output voltage of the wheel speed sensor with respect to time and producing an output voltage which is proportional to a rate decrease of the output voltage of the wheel speed sensor, fourth comparing means for comparing the output voltage of the second differentiating means with a second constant reference voltage and producing a fourth control signal when the former is higher than the latter, and a logical circuit responsive to the first, second, third and fourth control signals for producing a digital signal in the presence of the first control signal and the absence of the third control signal or in the presence of the second and fourth control signals and the absence of the third control signal for actuating said skid control means to reduce a braking force to be applied to said road wheel.

2. An electric control device as claimed in claim 1, in which said logical circuit comprises a logical inverter circuit having an input terminal to the third comparing means for inverting the third control signal, a first '"'"''"'"''"'"''"'"'NAND'"'"''"'"''"'"''"'"' gate circuit having a first input terminal connected to an output terminal of said first comparing means and a second input terminal connected to an output terminal of the inverter circuit, a second logical '"'"''"'"''"'"''"'"'NAND'"'"''"'"''"'"''"'"' gate circuit having a first input terminal connected to an output terminal of said second comparing means, a second input terminal connected to the output terminal of the inverter circuit and a third input terminal connected to an output terminal of said fourth comparing means, and a third '"'"''"'"''"'"''"'"'NAND'"'"''"'"''"'"''"'"' gate circuit having input terminals respectively connected to output terminals of the first and second '"'"''"'"''"'"''"'"'NAND'"'"''"'"''"'"''"'"' gate circuit.

3. An electric brake control device as claimed in claim 1, in which said computing means comprise a subtractor circuit having a first input terminal connected direct to said vehicle speed seNsor, a second input terminal connected through a first voltage divider to the output terminal of the vehicle speed sensor and a third input terminal connected to a constant voltage source so that said first variable reference voltage equals the output voltage of the vehicle speed sensor minus the sum of voltages applied to the second and third input terminals of the subtractor circuit.