# US 2008/0185241 A1 · Vehicle Braking System > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2008/0185241 A1 - Document ID: US20080185241A1 - Status: Published application - Kind: A1 - Application number: 11/997,056 - Filed: 2006-08-30 - Published: 2008-08-07 - Earliest claimed: 2005-08-31 - Assignees: Toyota Jidosha Kabushiki Kaisha - Inventors: Hiroshi Isono; Yasuji Mizutani - Web page: https://patentgrep.com/patent/US20080185241A1 ## CPC - B60T 8/4077: {Systems in which the booster is used as an auxiliary pressure source} - B60T 8/3655: {Continuously controlled electromagnetic valves} - B60T 8/441: {using hydraulic boosters (B60T8/445, B60T8/446, B60T8/447 take precedence)} - B60T 8/90: using a simulated speed signal to test speed responsive control means - B60T: VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL (electrodynamic brake systems for vehicle, in general B60L; brakes per se, i.e. devices where braking effect occurs, including ultimate brake actuators, F16D); ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES ## Abstract A vehicle braking system including an input piston and a pressure piston that are moveably supported within a cylinder. The input piston is allowed to depress the pressure piston and is connected to the a brake pedal. Pressure chambers to the front and to the rear of the input piston are communicated through a communication passage such that the control hydraulic pressure in accordance with the operation amount to the brake pedal is applied to the second pressure chamber via first and second linear valves. The control hydraulic pressure in accordance with the operation amount to the brake pedal that has been transmitted to the pressure piston through the input piston is regulated by a pressure regulating valve so as to be applied to the second pressure chamber. The braking hydraulic pressure may be output from the pressure chambers, respectively. ## Claims ### Claim 1 A vehicle braking system comprising: an input piston moveably supported within a cylinder along an axial direction; an operation portion connected to the input piston; a pressure piston provided coaxially with the input piston, moveably supported within the cylinder along its axial direction, which is allowed to be depressed by the input piston; a control hydraulic pressure setting unit that sets a control hydraulic pressure according to an operation amount inputted from the operation portion to the input piston; an electromagnetic hydraulic pressure supply unit that regulates a hydraulic pressure supplied from a hydraulic pressure supply source to the control hydraulic pressure so as to be applied to the input piston and the pressure piston such that a braking hydraulic pressure is generated; and a mechanical hydraulic pressure supply unit that regulates the hydraulic pressure supplied from the hydraulic supply source to the control hydraulic pressure according to the operation amount transmitted from the operation portion to the pressure piston through the input piston so as to be applied to the pressure piston such that the braking hydraulic pressure is generated. ### Claim 2 (depends on 1) The vehicle braking system according to claim 1, wherein either the electromagnetic hydraulic pressure supply unit or the mechanical hydraulic pressure supply unit regulates the control hydraulic pressure. ### Claim 3 (depends on 1) The vehicle braking system according to claim 1, wherein the mechanical hydraulic pressure supply unit does not regulate the control hydraulic pressure as long as the electromagnetic hydraulic pressure supply unit is regulating the control hydraulic pressure. ### Claim 4 (depends on 1) The vehicle braking system according to claim 1, further comprising an operation force absorbing unit that absorbs an operation force input from the operation portion to the input piston. ### Claim 5 (depends on 4) The vehicle braking system according to claim 4, wherein: the electromagnetic hydraulic pressure supply unit is capable of supplying the control hydraulic pressure to one of a first pressure chamber and a second pressure chamber in a moving direction of the input piston; and the operation force absorbing unit includes a communication passage formed in the input piston, through which a compression fluid is supplied and released between the first pressure chamber and the second pressure chamber. ### Claim 6 (depends on 5) The vehicle braking system according to claim 5, wherein the communication passage includes a portion having its diameter reduced. ### Claim 7 (depends on 5) The vehicle braking system according to claim 5, wherein: the electromagnetic hydraulic pressure supply unit includes a first hydraulic pressure supply line connected between the hydraulic pressure supply source and one of the first and the second pressure chambers, a first electromagnetic valve which is provided in the first hydraulic pressure supply line, and closed in a state where an electric current is not supplied, a first hydraulic pressure exhaust line which is connected between one of the first and the second pressure chambers and a reservoir, and a second electromagnetic valve which is provided in the first hydraulic pressure exhaust line, and opened in the state where the electric current is not supplied, and the electromagnetic hydraulic pressure supply unit regulates the hydraulic pressure supplied from the hydraulic pressure supply source to the control hydraulic pressure by adjusting opening degrees of the first and the second electromagnetic valves. ### Claim 8 (depends on 5) The vehicle braking system according to claim 5, wherein: the mechanical hydraulic pressure supply unit includes a pressure regulating valve which is operated in response to a depression to the pressure piston performed by the input piston upon operation of the operation portion, a second hydraulic pressure supply line connected between the hydraulic pressure supply source and the pressure regulating valve, and a third hydraulic pressure supply line that connects the pressure regulating valve and the first pressure chamber; and an opening degree of the pressure regulating valve is adjusted by operating the operation portion to regulate the hydraulic pressure supplied from the hydraulic pressure supply source to the control hydraulic pressure. ### Claim 9 (depends on 8) The vehicle braking system according to claim 8, wherein: the communication passage is closed when the input piston is moved to be close to the pressure piston by operating the operation portion; the mechanical hydraulic pressure supply unit applies the control hydraulic pressure regulated by the pressure regulating valve to generate the braking hydraulic pressure; and the communication passage is opened when the input piston is moved away from the pressure piston by operating the operation portion such that the braking hydraulic pressure is reduced. ### Claim 10 (depends on 8) The vehicle braking system according to claim 8, wherein the pressure regulating valve includes a poppet valve that closes and opens the second and the third hydraulic pressure supply lines, an urging member that urges the poppet valve into a closing direction, and a moveable member that is moved by the operation of the operation portion to open the poppet valve. ### Claim 11 (depends on 8) The vehicle braking system according to claim 8, wherein the pressure regulating valve is accommodated in the pressure piston, and the third hydraulic pressure supply line is provided within the cylinder. ### Claim 12 (depends on 10) The vehicle braking system according to claim 10, wherein the communication passage is closed when the input piston is moved to be in contact with the moveable member, and the moveable member moves the poppet valve so as to establish a communication between the second and the third hydraulic pressure supply lines. ### Claim 13 (depends on 8) The vehicle braking system according to claim 8, wherein: the pressure regulating valve is provided to a leading end of the cylinder; the third hydraulic pressure supply line is provided outside of the cylinder; the communication passage is closed when the input piston is moved to be in contact with the pressure piston; and the hydraulic pressure caused by a movement of the pressure piston allows the moveable member to move the poppet valve so as to establish a communication between the second and the third hydraulic pressure supply lines. ### Claim 14 (depends on 13) The vehicle braking system according to claim 13, wherein: a switching valve is provided in the third hydraulic pressure supply line and is opened and closed depending on a position of the poppet valve; a second hydraulic pressure exhaust line is connected between the pressure regulating valve and the reservoir; the third hydraulic pressure supply line is closed, and the second hydraulic pressure exhaust line is opened during an operation of the electromagnetic hydraulic pressure supply unit; and the third hydraulic pressure supply line is opened, and the second hydraulic pressure exhaust line is closed during an operation of the mechanical hydraulic pressure supply unit. ### Claim 15 (depends on 1) The vehicle braking system according to claim 1, wherein the mechanical hydraulic pressure supply unit is not allowed to generate the braking hydraulic pressure when the control hydraulic pressure is applied to the pressure piston by the electromagnetic hydraulic pressure supply unit to generate the braking hydraulic pressure. ### Claim 16 (depends on 1) The vehicle braking system according to claim 1, wherein a first pressure receiving area of the input piston is set to be smaller than a second pressure receiving area of the pressure piston. ### Claim 17 (depends on 1) The vehicle braking system according to claim 1, further comprising a normal operation determination unit which allows the electromagnetic hydraulic pressure supply unit to apply a predetermined control hydraulic pressure to the input piston through which the pressure piston is moved to forcibly operate the mechanical hydraulic pressure supply unit, and determines with respect to a normal operation of the mechanical hydraulic pressure supply unit based on the braking hydraulic pressure. ### Claim 18 (depends on 1) The vehicle braking system according to claim 1, further comprising a normal operation determination unit which allows the electromagnetic hydraulic pressure supply unit to apply a predetermined control hydraulic pressure to the input piston so as to be moved to be close to the pressure piston such that the communication passage is closed, allows the input piston to move the pressure piston to forcibly operate the mechanical hydraulic pressure supply unit, and determines based on a generated braking hydraulic pressure whether or not the operation of the pressure regulating valve is normal. ### Claim 19 (depends on 15) The vehicle braking system according to claim 15, wherein: the electromagnetic hydraulic pressure supply unit and the mechanical hydraulic pressure supply unit apply the control hydraulic pressure to the pressure piston to allow the first and the second braking hydraulic pressures to be discharged from the first pressure chamber and a third pressure chamber of the pressure piston, respectively; the normal operation determination unit closes the second electromagnetic valve, and opens the first electromagnetic valve before starting a vehicle to apply a predetermined control hydraulic pressure to the input piston so as to make a determination with respect to the normal operation of the pressure regulating valve upon establishment of the conditions that: the second braking hydraulic pressure is equal to or higher than a predetermined second reference braking hydraulic pressure, and an operation amount of the operation portion is in a predetermined reference operation range. ### Claim 20 (depends on 19) The vehicle braking system according to claim 19, wherein the normal operation determination unit determines that the operation of the pressure regulating valve is normal if the first braking hydraulic pressure is equal to or higher than a predetermined first reference braking hydraulic pressure after an elapse of a predetermined time period from a time at which the second braking hydraulic pressure becomes equal to or higher than a second reference braking hydraulic pressure, and the operation amount to the operation portion is within a reference operation range. ### Claim 21 (depends on 18) The vehicle braking system according to claim 18, wherein before starting the vehicle, the normal operation determination unit further closes the discharge line of the second braking hydraulic pressure from the third pressure chamber. ### Claim 22 (depends on 19) The vehicle braking system according to claim 19, wherein the normal operation determination unit closes the second electromagnetic valve and opens the first electromagnetic valve when the vehicle is estimated to start such that the predetermined control hydraulic pressure is applied to the input piston. ### Claim 23 (depends on 18) The vehicle braking system according to claim 18, wherein the second braking hydraulic pressure is obtained through an operation of the operation portion performed by an occupant of the vehicle. ### Claim 24 (depends on 18) The vehicle braking system according to claim 18, wherein the second braking hydraulic pressure is obtained through application of the predetermined control hydraulic pressure to the input piston. ### Claim 25 (depends on 18) The vehicle braking system according to claim 18, wherein: the electromagnetic hydraulic pressure supply unit and the mechanical hydraulic pressure supply unit apply the control hydraulic pressure to the pressure piston to allow the first and the second braking hydraulic pressures to be discharged from the first pressure chamber and the third pressure chamber in the pressure piston; the normal operation determination unit closes the second electromagnetic valve and opens the first electromagnetic valve when the vehicle is estimated to start so as to make a determination with respect to the normal operation of the pressure regulating valve upon establishment of conditions that: the second braking hydraulic pressure obtained through application of the predetermined control hydraulic pressure to the input piston is equal to or higher than the predetermined second reference braking hydraulic pressure, and an operation amount to the operation portion is in the predetermined reference operation range. ### Claim 26 (depends on 25) The vehicle braking system according to claim 25, wherein the normal operation determination unit determines that the operation of the pressure regulating valve is normal if the first braking hydraulic pressure is equal to or higher than a predetermined first reference braking hydraulic pressure after an elapse of a predetermined time period from a time at which the second braking hydraulic pressure becomes equal to or higher than a second reference braking hydraulic pressure, and the operation amount to the operation portion is within a reference operation range upon estimation of the vehicle start-up. ### Claim 27 (depends on 25) The vehicle braking system according to claim 25, wherein when the vehicle is estimated to start, the normal operation determination unit closes the discharge line of the second braking hydraulic pressure from the third pressure chamber so as to decompress the discharge line of the first braking hydraulic pressure from the first pressure chamber. ### Claim 28 (depends on 27) The vehicle braking system according to claim 27, wherein the normal operation determination unit stops decompression in the discharge line of the first braking hydraulic pressure from the first pressure chamber, and returns the reduced first braking hydraulic pressure to the discharge line of the first braking hydraulic pressure after completion of the determination with respect to the normal operation of the pressure regulating valve. ### Claim 29 (depends on 8) The vehicle braking system according to claim 8, wherein a hydraulic pressure motor serving as the hydraulic pressure supply source is stopped and the first and the second electromagnetic valves are opened to set a static pressure mode when an abnormality occurs in a supply hydraulic pressure of the second hydraulic pressure supply line. ### Claim 30 (depends on 29) The vehicle braking system according to claim 29, wherein in the static pressure mode, the hydraulic pressure motor is driven and an opening degree of the second electromagnetic valve is adjusted upon an operation of the operation portion performed by the occupant of the vehicle.