Vehicle brake system
First Claim
1. A vehicle brake system including a force multiplier apparatus which includes a shell body, a power piston displaceably mounted in the shell body through a diaphragm, a control chamber defined in the power piston, a partition wall means displaceably mounted in the control chamber to define two control chambers, said power piston defining within the shell body a front chamber and a rear chamber, and a valve mechanism in said power piston which cooperates with an input member to control pressure between said chambers, whereby when a pressure difference is produced in said front and rear chambers by operating the input member, a thrust is produced in the power piston which is transmitted to an output shaft, and the reaction force produced in the output shaft is transmitted to the input member, said system further comprising a controller operatively connected to a vehicle speed sensor, an acceleration switch, a manual brake switch and, change-over valve means, said change-over valve means cooperating with said input member to increase, maintain, and decrease force by controlling introduction of atmospheric air or negative pressure into one of the control chambers defined in said power piston, the other control chamber communicating with said front chamber in said shell body which is connected with said negative pressure, said controller controlling said change-over valve means under specified conditions, said controller comprising a deceleration calculating circuit for calculating the amount of deceleration of the vehicle, a timer which is actuated when said manual brake switch is ON and which determines the operation timing of said deceleration calculation circuit, a comparator circuit for comparing the output of said deceleration calculating circuit with predetermined values so as to judge the operating condition of the vehicle, and a command signal transmitting circuit for producing brake force increase, maintain and decrease signals corresponding to the vehicle operating conditions judged by the comparator circuit.
1 Assignment
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Accused Products
Abstract
In a vehicle brake system including a pneumatic force multiplier apparatus in which a power piston moves by virtue of a pressure difference between atmospheric and negative pressure, a manual brake switch is provided to apply braking force without need for depressing the brake pedal. A controller includes a deceleration calculating circuit reading vehicle speed for every specified number of seconds and calculating the amount of deceleration. The deceleration is compared with a predetermined value and braking force is increased, maintained, or decreased depending on whether the vehicle is running on a downwardly sloping, level, or unwardly sloping road.
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Citations
1 Claim
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1. A vehicle brake system including a force multiplier apparatus which includes a shell body, a power piston displaceably mounted in the shell body through a diaphragm, a control chamber defined in the power piston, a partition wall means displaceably mounted in the control chamber to define two control chambers, said power piston defining within the shell body a front chamber and a rear chamber, and a valve mechanism in said power piston which cooperates with an input member to control pressure between said chambers, whereby when a pressure difference is produced in said front and rear chambers by operating the input member, a thrust is produced in the power piston which is transmitted to an output shaft, and the reaction force produced in the output shaft is transmitted to the input member, said system further comprising a controller operatively connected to a vehicle speed sensor, an acceleration switch, a manual brake switch and, change-over valve means, said change-over valve means cooperating with said input member to increase, maintain, and decrease force by controlling introduction of atmospheric air or negative pressure into one of the control chambers defined in said power piston, the other control chamber communicating with said front chamber in said shell body which is connected with said negative pressure, said controller controlling said change-over valve means under specified conditions, said controller comprising a deceleration calculating circuit for calculating the amount of deceleration of the vehicle, a timer which is actuated when said manual brake switch is ON and which determines the operation timing of said deceleration calculation circuit, a comparator circuit for comparing the output of said deceleration calculating circuit with predetermined values so as to judge the operating condition of the vehicle, and a command signal transmitting circuit for producing brake force increase, maintain and decrease signals corresponding to the vehicle operating conditions judged by the comparator circuit.
Specification
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- Resources
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Current AssigneeTokico Limited (Hitachi, Ltd.)
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Original AssigneeTokico Limited (Hitachi, Ltd.)
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InventorsTakayama, Toshio, Matsumoto, Yukio
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Primary Examiner(s)Stoner, Jr., Bruce H.
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Assistant Examiner(s)OBERLEY, ALVIN E
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Application NumberUS06/736,121Time in Patent Office477 DaysField of Search303/93, 303/97, 303/20, 303/100, 303/105, 303/113, 303/114, 303/106, 303/119, 188/181 A, 188/181 R, 188/181 C, 188/357, 60/545, 91/519, 92/49, 180/282US Class Current303/192CPC Class CodesB60T 13/241 Differential pressure systemsB60T 8/17616 Microprocessor-based systemsB60T 8/38 including valve means of th...
