Abstract: A brake system 1 of the present invention comprises a brake operating means 2 such as a brake pedal for carrying braking operation, a fluid variable stroke means 3 which variably controls the stroke of the brake operating means 2 by using fluid, and a braking force output means 4 which is actuated by the operation of the brake operating means 2 to produce braking forces. By manipulating the brake operating means 2, the braking force output means 4 performs the braking operation. The traveling rang of the brake operating means 2 i.e. the stroke can be changed variously by the fluid variable stroke means 3 using fluid. Since the stroke of the brake pedal can be changed as mentioned above, a proper pedal stroke can be obtained.

Abstract: A motor vehicle tandem brake power booster with two booster units each including a vacuum chamber and a working chamber each arranged in a partition divided housing. The pressure difference between the pressure in the vacuum chamber and the pressure that can be influenced by a switching device in the corresponding working chamber in each booster unit acts on a piston separating the vacuum chamber from the working chamber. The forces, which are proportional to the pressure difference and act on the pistons are bundled via mechanical intermediate members by at least one transmission element each with the forces applied by the driver of the vehicle to a corresponding brake pedal.

Abstract: A hydraulic pressure brake device includes a master cylinder, a brake operating member, a master piston, a booster, a first auxiliary piston, a pressure transmitting chamber, a valve device, and a second auxiliary piston. The hydraulic pressure brake device further includes an output member and a rod. The output member is provided in the booster for transmitting the boosting power generated by the booster to the first auxiliary piston when the movement of the master piston is assisted by the booster. The rod is provided in the second auxiliary piston for transmitting the operating force applied to the brake operating member to the valve device and for opening the valve device when the movement of the master piston is not assisted by the booster.

Abstract: A hydraulic brake apparatus is provided for increasing a braking force with a brake feeling similar to that during a normal brake operation, even if a brake pedal is operated during an automatic brake operation. A valve device having a spool is placed in a power piston and is transferred between first and second positions depending on the operation of the brake pedal. At the first position, a power chamber is at atmospheric pressure level, while at the second position a fluid communication is established between the power chamber and an auxiliary hydraulic pressure source. The spool is driven independent of the operation of the brake pedal. When a hydraulic pressure is applied to the spool, the valve device is switched to the second position, urging the power piston to advance, without transmitting the resultant force to the brake operation member. The driving device, when applied with no hydraulic pressure, retains the valve device at the first position.

Abstract: A hydraulic system for actuating at least two operating systems of a motor vehicle has a first hydraulic medium reservoir for storing a hydraulic medium. A distribution valve is connected to the first hydraulic medium reservoir and to the operating systems of the motor vehicle. A control unit is connected to the distribution valve which is configured to distribute the hydraulic medium from the first hydraulic medium reservoir to the operating systems of the motor vehicle and to control flow of the hydraulic medium to the operating systems of the motor vehicle such that one of the operating systems has priority with regard to supply of the hydraulic medium. A first one of the operating systems is a brake device having a brake power assist unit, a brake valve, and a master brake cylinder. The brake power assist unit is connected via the brake valve to the control unit.

Abstract: A brake system includes first brake assist means arranged in a first brake circuit to increase a first wheel cylinder pressure to a level higher than a master cylinder pressure. The brake system further includes second brake assist means arranged in a second brake circuit to increase a second wheel cylinder pressure to a level higher than the master cylinder pressure. The second brake assist means includes a brake regulator mechanism that uses the increased first wheel cylinder pressure as a pilot pressure and adjusts the increased second wheel cylinder pressure to a pressure falling within a predetermined range from the increased first wheel cylinder pressure when the first brake assist means is activated.

Abstract: The reliability of a pressure sensor is improved either by utilization of redundant components. A pair of pressure sensors are mounted upon a single pressure sensor diaphragm. The pressure signals generated by the pressure sensors are compared and, if the difference between the signals exceeds a predetermined threshold, it is determined that a malfunction of the pressure sensor has occurred. Alternately, additional diagnostic testing may be included to detect a malfunctioning sensor.

Abstract: A vehicle braking pressure source device including (a) a master cylinder having a pressurizing piston cooperating with a cylinder housing to define a pressurizing chamber and a back-pressure chamber on front and rear sides of the piston, and an input rod which slidably extending through a rear end wall of the cylinder housing such that the piston is advanced by a brake operating force of a brake operating member transmitted thereto through the input rod, to pressurize a working fluid in the pressurizing chamber, (b) a communication passage for communication between the pressurizing and back-pressure chambers, (c) a control valve device disposed in the communication passage for controlling the communication between the pressurizing and back-pressure chambers through the communication passage, and (d) a control valve control device for controlling the control valve device, on the basis of at least one of an operating state of the brake operating member, a running state of the vehicle and a state of a road surfa

Abstract: A braking pressure control apparatus for a hydraulically operated brake, including a first hydraulic system having a first hydraulic pressure source power-operated to pressurize a working fluid and capable of controlling the fluid pressure, for operating the brake, a second hydraulic system having a second hydraulic pressure source operable by an operating force acting on a manually operable brake operating member, to pressurize the working fluid to a pressure higher than a level corresponding to the operating force, for operating the brake, a switching device operable to selectively establish a first state in which the brake is operated with the pressurized fluid delivered from the first hydraulic pressure source, and a second state in which the brake is operated with the pressurized fluid delivered from the second hydraulic pressure source, and a diagnosing device operable to diagnose the second hydraulic system on the basis of the fluid pressure in the second hydraulic system.

Abstract: The present invention is directed to a brake control system, which includes wheel brake cylinders, a master cylinder, a reservoir communicated with the wheel brake cylinders, normally open solenoid valves disposed between the master cylinder and the wheel brake cylinders, respectively, normally closed solenoid valves disposed between the wheel brake cylinders and the reservoir, respectively, a hydraulic pump for supplying the brake fluid to a passage for connecting the master cylinder with the normally open valves, and an automatically pressurizing device (e.g., a vacuum booster with a changeover valve) which is provided for advancing the master piston irrespective of operation of the pump and the brake pedal to generate hydraulic braking pressure from the master cylinder.

Abstract: A vehicle braking system including a master cylinder having a pressurizing piston fluid-tightly and slidably received in a cylinder housing and cooperating with the cylinder housing to define a pressurizing chamber and an assisting chamber on opposite sides of the piston, a brake operating member for applying a pressurizing force to the piston, a wheel brake cylinder connected to the master cylinder for activating a brake for braking a wheel, a hydraulic pressure source for pressuring a working fluid, a reservoir, a first flow control device for controlling flows of the fluid between the assisting chamber, and the hydraulic pressure source and reservoir, and a second flow control device or controlling flows of the fluid between the pressurizing chamber, and the hydraulic pressure source and reservoir.

Abstract: A vacuum booster apparatus used for a brake apparatus positively decreases a degree of opening of a throttle valve when it is required while an unnecessary decrease in the degree of opening of the throttle valve is positively prevented. A first pressure chamber of a vacuum booster is connected to an intake pipe of the engine on a downstream side of a throttle valve. A second pressure chamber of the vacuum booster is selectively connectable to one of the first pressure chamber and atmosphere. The vacuum booster boosts an operating force applied to a brake operating member based on a pressure difference between the first pressure chamber and the second pressure chamber. A throttle-opening-degree control device controls a negative pressure in the first pressure chamber by controlling the degree of opening of the throttle valve.

Abstract: A brake system for (10) a vehicle having a brake booster (14a) with an output put rod (152a) for providing a primary piston (310) in a master cylinder (12a) with an input force to pressurize fluid which is supplied to wheel brakes (10a) of a vehicle to effect a brake application in response to an operator input force. The master cylinder (12a) has a first housing (202a) with a bore (202a) therein for retaining the primary piston (310) in a first pressure chamber (212a). The bore (202a) has a first compensation passage (206a) connected to a fluid supply (204a) and an outlet port (218) connected to the wheel brakes (10a). The primary piston (310) has a first position of rest whereby the first pressure chamber (212a) is connected to a fluid supply (204a) through the first compensation passage (206a). The brake booster (14a) has a second housing (102,104) with an interior separated by a movable wall (122) into a front chamber (108) and a rear chamber (110).

Abstract: The present invention is directed to a hydraulic brake apparatus, which includes wheel brake cylinders, and a master cylinder for advancing a master piston in response to operation of a brake pedal. A power chamber is formed behind the master piston. A reaction piston is disposed, with the front end thereof exposed in the power chamber, so as to transmit a reaction force produced by the pressure in the power chamber to the brake pedal. A power source is provided for pressurizing brake fluid stored in a reservoir to supply power pressure to the power chamber. A solenoid valve is provided for opening and closing a return passage which connects the power chamber to the reservoir, thereby to return the brake fluid thereto. A detection device is provided for detecting the amount of operation of the brake pedal. The solenoid valve is controlled in response to the amount of operation detected by the detection device to reduce the amount of the brake fluid in the power chamber.

Abstract: A diagnosing apparatus for diagnosing a pressurizing device provided in a hydraulically operated braking system operated by a brake operating member, wherein a hydraulic pressure detecting device is operable to detect a hydraulic pressure which is a sum of a first fluid pressure generated by an operation of the brake operating member, and a second fluid pressure generated by an operation of the pressurizing device, and a diagnosing device is operable to determine whether the pressurizing device is abnormal or not, on the basis of the hydraulic pressure detected while the brake operating member is not in operation and while the pressurizing device is in operation.

Abstract: A control method of a hydraulic pressure source-driving type vehicle hydraulic brake system is provided in which water hammering or worsening of the brake feeling does not occur when brake liquid is replenished through a replenish passage. A motor for driving a pump is actuated at a full driving force with an on-off valve in the brake liquid replenish passage opened in the stage in which the hydraulic pressure difference between the master cylinder pressure and the brake hydraulic pressure is small. Also, in the stage in which the brake hydraulic pressure is increased, so that the hydraulic pressure difference from the master cylinder hydraulic pressure has entered a predetermined range, a solenoid valve in the replenish passage is closed to return to the normal control in which the driving force of the motor is controlled so as to correspond to the hydraulic pressure difference.

Abstract: A substantially constant brake assist gain is provided in a vehicle braking system having a vacuum booster providing braking assist to a brake fluid master cylinder in response to an operator input braking force, even though the gain of the booster falls off from its maximum value in a non-linear manner in a runout initiating portion of the working vacuum range near zero booster vacuum. A brake fluid pump, such as is used in an ABS/TCS modulator, is used to supplement the booster output as it falls so as to maintain a constant, linear brake system gain into runout. In the runout initiating portion of the working vacuum range, a runout assist gain is derived from stored data expressing booster assist gain as a function of booster vacuum, and a target wheel pressure is calculated from the derived runout boost assist gain and a corresponding change in master cylinder pressure.

Abstract: A brake pressure control device is described. The device includes a pneumatic brake booster which has at least two chambers that are separable from each other. At least one of the chambers can be operated as a low-pressure chamber and at least another one of the chambers can be oerated as a working chamber. The device further includes a master braking cylinder in which a master cylinder pressure is generated over the pneumatic brake booster, and a hydraulic unit, which is installed between the master cylinder and at least one wheel brake cylinder of at least one wheel. The hydraulic unit includes an arrangement of switchable valves as well as least one pump. A hydraulic boost of the brake pressure is achievable with the assistance of the hydraulic unit. A wheel brake cylinder pressure may be generated in the at least one wheel brake cylinder with the assistance of the hydraulic unit, the wheel brake cylinder pressure being greater than the master cylinder pressure.

Abstract: A brake system including a negative pressure booster, a master cylinder of tandem type and an intensifying arrangement. The intensifying arrangement defines an intensifying chamber disposed rearward of a primary piston, a pump for supplying a braking liquid to the intensifying chamber, and a reaction piston and a sleeve for controlling the pressure of the braking liquid which is supplied to the intensifying chamber. As a brake pedal is depressed and the intensifying arrangement is actuated, a sum of an urging force from the negative pressure booster and an urging force from the intensifying arrangement operates the primary piston to develop a master cylinder pressure. The sum is proportional to the input or a force depressing the brake pedal.

Abstract: The present invention is directed to a brake control system for a vehicle, which includes a cut-off valve for opening or closing a main passage, which communicates a master cylinder with a wheel brake cylinder, and a pump for discharging the pressurized brake fluid to the wheel brake cylinder, with an outlet of the pump connected to a position between the cut-off valve and the wheel brake cylinder. An inlet valve is provided for opening or closing an auxiliary passage which communicates an inlet of the pump with the master cylinder. And, a controller is adapted to place the cut-off valve in a closed position thereof, place the inlet valve in an open position thereof, and actuate the pump to supply the pressurized brake fluid discharged from the pump into the wheel brake cylinder, when a brake-assist control is to be performed.

Abstract: A braking force control device and method performs brake assist control. A timer CT begins to count the elapsed time, for example, from when the elevation gradient &Dgr;PM/C of a master cylinder pressure PM/C becomes equal to or greater than a first threshold value TH2. It is determined that an emergency brake operation is executed, when the master cylinder pressure PM/C becomes equal to or greater than a second threshold value TH1 before a predetermined time has passed, and then the brake assist control starts.

Abstract: A vehicle brake control system includes a brake booster divided into a constant pressure chamber permanently communicating with a vacuum source, and a variable pressure chamber selectively communicating with the constant pressure chamber. The brake booster includes a first servo mechanism designed to develop a differential pressure between the two chambers, and a second servo mechanism. A master cylinder is operatively connected to the brake booster to create hydraulic pressure in response to the output of the brake booster, and hydraulic lines connect the master cylinder and the wheel cylinders. Pressure charging valves allow and block communication between the master and the wheel cylinders. Pressure relief valves between the pressure charging valves and the wheel cylinders selectively release the hydraulic pressure from the hydraulic lines.

Abstract: A hydraulic brake system for a vehicle for braking the vehicle by brake pedal actuation and/or automatic braking. A pump is provided which has a suction connection that communicates with a supply container for a pressure fluid and a pressure connection for aspirating pressure fluid from the supply container and pumping the fluid to a connection of a master cylinder. A brake circuit of the vehicle brake system is connected with vehicle wheels associated with wheel brake cylinders and with valve assemblies for brake pressure modulation and is connected to the connection of the master cylinder. A valve pressure is also provided between a pressure chamber that communicates with the connection of the master cylinder and the supply container for pressure fluid.

Abstract: A negative pressure control apparatus for a brake booster is provided which can always maintain a required negative pressure in a negative pressure chamber of the brake booster in a system including a direct-injection engine. The apparatus has a brake operation predicting part for predicting execution of a brake operation by a driver. When execution of a brake operation is predicted, negative pressure in the negative pressure chamber is controlled to be a required value.

Abstract: The invention discloses an automatic brake system for motor vehicles which serves to shorten the stopping distance by means of propulsion motor vehicle control signals while simultaneously lowering the required costs. According to the invention, means are provided which ensure pre-filling of the wheel brakes when a control signal which represents the motion of the gas pedal when the actuating force is discontinued is received by the brake system control unit.

Abstract: A method and device for estimating pressure changes within a hydraulic system having a first reservoir and at least one second reservoir connected to the first reservoir via valves, including the following steps: (a) specifying a pressure differential between the first and second reservoirs; (b) calculating a volume exchanged within a specified time interval between the first and second reservoirs via the valve, on the basis of a value for the pressure differential that is valid at the start of the time interval; (c) calculating a volume to be exchanged between the two reservoirs to achieve equal pressures in them; (d) if the amount of the exchanged volume calculated in step (b) is greater than the volume to be exchanged as calculated in step (c), replacing the value of the exchanged volume with that of the volume to be exchanged; and (e) adopting the volume value obtained in step (d) as the change in the volume in the second reservoir and determining the pressure change in the reservoirs on the basis of

Abstract: A hydraulic brake system which incorporates several mutually independent brake circuits and does not require additional energy for conducting brake-slip control actions or stability control actions.

Abstract: When a stroke speed exceeds a reference value of a stroke speed threshold value, a solenoid is energized to tract an armature, thereby opening an atmospheric valve independently of the position of a plunger. Consequently, power pistons, together with an output rod, are moved forward by a thrust corresponding to a pressure difference between a constant-pressure chamber and a variable-pressure chamber to perform a full-power braking operation. A reaction-adjusting mechanism contributes to an improvement in safety by functioning in such a way that when the part of the reaction force from the output shaft that is transmitted to an input rod reaches a predetermined value, a boosting ratio is increased, so that the reference value of the stroke speed threshold value can be set high to prevent unnecessary braking.

Abstract: An electronically controllable brake booster with a vacuum chamber and a pressure chamber, which are separated from each other by a movable wall, a control valve arrangement which can be actuated by an electromagnetic actuation device, through which a pressure difference between the pressure chamber and the vacuum chamber can be adjusted, with the control valve arrangement, as a function of a current flowing through the electromagnetic actuation device, assuming a holding position in which the current ranges between a higher value and a lower value without the control valve arrangement leaving the holding position, a first pressure changing position in which the current is higher than the higher value, and a second pressure changing position in which the current is lower than the low value, characterised in that upon a changeover of the control valve arrangement from the holding position into the first or the second pressure changing position, or upon a changeover from the first or the second pressure changin