Abstract: In a braking pressure intensifying master cylinder of the present invention, as an input shaft 53 travels forwards in a braking maneuver, a control valve 54 is actuated to develop fluid pressure according to the input in a reaction chamber 38 and a pressurized chamber 35. A stepped spool 45 as a part of the control valve 54 travels such that force produced by the fluid pressure and spring force of a spring 51 are balanced, whereby the stepped spool 45 can function as a travel simulator. By changing the pressure receiving areas of the stepped spool 45 and/or changing the spring force of the spring 51, the travel characteristic of the input shaft 53 as the input side can be freely changed independently from the output side, without influence on MCY pressure as the output side of the braking pressure intensifying MCY 1. In addition, the master cylinder pressure can be intensified when necessary with a simple structure.

Abstract: A braking force control device is provided in which wheel speeds of respective wheels of a vehicle are detected. On the basis of detected wheel speeds, a road surface &mgr; slope, which is a slope of a coefficient of friction &mgr; between a wheel and a road surface, is estimated for each wheel. On the basis of the road surface &mgr; slope estimated for each wheel, a braking force of each wheel is controlled such that the braking force of each wheel is adjusted.

Abstract: A master cylinder which includes a primary piston and a thrust piston disposed within a housing, and defines an intensifying chamber at a location rearward of the thrust piston. An input shaft has a front end which is disposed within the intensifying chamber. The thrust piston is formed with a communication path (discharge passage), and a control valve is disposed between the thrust piston and the front end of the input shaft to open or close the communication path (discharge passage). When the input shaft is driven forward under the inoperative condition shown and the pump is operated to introduce a discharge pressure from the pump into the intensifying chamber, a liquid pressure is generated in the intensifying chamber and drives the primary piston forward, generating a liquid pressure in a liquid pressure chamber. In this manner, a master cylinder can be provided which has a simple and inexpensive construction with a reduced number of parts and which is compact in size.

Abstract: A brake control device has a master cylinder, wheel cylinder, and a solenoid valve disposed in a conduit between the master cylinder and the wheel cylinder. When a brake pedal happens to be returned at sudden braking, at an idle stop or at vehicle stop on a sloping road, the solenoid valve is controlled at a duty rate based on a difference between a peak value of master cylinder and an actual value of master cylinder reducing so that wheel cylinder pressure is held to a value higher than master cylinder pressure.

Abstract: In a brake fluid pressure boosting device 1 of the present invention, by operation, an input shaft 4 is moves forward to rotate a lever 27 to actuate a control valve 8 so that the control valve 8 produce working fluid pressure corresponding to the input. The working fluid pressure is introduced into the power chamber 6. By this working fluid pressure, the primary piston 37 is actuated to develop master cylinder pressure. On the other hand, the fluid pressure of the power chamber 6 is introduced into the first annular groove 25 of the valve spool 10. By the difference between pressure receiving areas of the first annular groove 25, the valve spool 10 is subjected to rightward force. The position of the pivot of the lever 27 is fixed and the valve spool 10 is controlled in such a manner that the force applied to the valve spool 10 and the spring force of the spool return spring 32 balances with the input, thereby exhibiting the function as a stroke simulator.

Abstract: In a brake apparatus of the present invention, as MCY pressure is developed by a master cylinder (MCY) 1 according to the forward movement of a primary inner piston 9, a pump of a braking force control device arranged between the MCY 1 and wheel cylinders (WCYs) sucks up hydraulic fluid from the MCY 1 to discharge the hydraulic fluid to the WCYs. Thus, WCY pressure controlled according to operational conditions of various modes is developed. The WCY pressure is supplied to a control pressure chamber 40 to act on a step 8e of a primary outer piston 8. The primary outer piston 8 moves relative to the primary inner piston 9 in such a manner that the force produced by the MCY pressure, the force produced by the WCY pressure, the spring force of a control spring 13, and the frictional force of fluid-tightly slidable portions of the primary outer piston 8 are balanced, whereby the pedal travel can remain the same as that in service braking mode.

Abstract: A braking force control device is provided in which wheel speeds of respective wheels of a vehicle are detected. On the basis of detected wheel speeds, a road surface &mgr; slope, which is a slope of a coefficient of friction &mgr; between a wheel and a road surface, is estimated for each wheel. On the basis of the road surface &mgr; slope estimated for each wheel, a braking force of each wheel is controlled such that the braking force of each wheel is adjusted.

Abstract: A braking force distribution control device is provided in which wheel speeds of respective wheels of a vehicle are detected. On the basis of the detected wheel speeds, slopes of coefficients of friction &mgr; between the wheels and a road surface are estimated as road surface &mgr; slope values of the respective wheels. On the basis of the estimated road surface &mgr; slope values of the respective wheels, braking forces of the respective wheels are controlled such that the braking forces among the respective wheels are adjusted.

Abstract: The invention relates to a brake system including a brake booster. A pneumatic pressure operated brake booster VBB or a liquid pressure operated brake booster includes a valve mechanism which is urged by a force of depression applied to a brake pedal BP to switch a flow path to cause the brake booster to develop an output which depends on the magnitude of the force of depression. A solenoid SOL urges the valve mechanism in the same direction as or in the opposite direction from the force of depression. A controller ECU is responsive to a braking effort increase/decrease demand signal to increase or decrease the urging force which is applied by the solenoid to the valve mechanism, thus increasing or decreasing the output from the brake booster. An output from the brake booster can be freely controlled independently from the force of depression applied to the brake pedal in response to a, braking effort increase/decrease demand.

Abstract: A tire parameter estimation device that is economical and can accurately estimate tire parameters while taking into consideration both states of a vehicle and states of a road environment. A &mgr; gradient detecting circuit detects a &mgr; gradient on the basis of a wheel speed detected by a wheel speed detecting circuit. A gradient value comparing circuit determines a &mgr; gradient section value &mgr;r, which is a mean value of the &mgr; gradients from the &mgr; gradient detecting circuit, and calculates a rate (=&mgr;r/&mgr;I) of the &mgr; gradient mean value &mgr;r with respect to a &mgr; gradient initial value &mgr;. A tire temperature estimating circuit stores a table representing the relation between the rate and a tire temperature, and estimates a tire temperature corresponding to the rate calculated by the gradient value comparing circuit as the present tire temperature.

Abstract: A braking force control device, wherein wheel speed is detected and a slope of a braking force with respect to slip speed of the wheel is estimated on the basis of the detected wheel speed, a braking operation by which a brake pedal is depressed is detected and, on the basis of the detected braking operation conditions and estimated slope of the braking force, braking of the braking device to brake the wheels by a braking force generated in response to the braking operation by which the brake pedal is depressed is assisted.

Abstract: An apparatus for detecting abnormality of a vehicle sensor and a method are provided. The apparatus is capable of preventing erroneous detection of abnormalities of sensors. The apparatus has a grip degree detecting device for detecting grip degree of a wheel of the vehicle with respect to a road surface. In a case in which the grip degree is lower than a predetermined degree, detection for presence of an abnormality of a yaw rate sensor, a cross acceleration sensor and a steering angle sensor are prohibited.

Abstract: a motor coil-shorting detecting unit is provided which determines the existence of a short. The coil shorting detecting unit includes a current sensor for detecting the value of current supplied to a motor from a power source, and a controller for making the shorting determination of coils by comparing a detected voltage or current with a pre-stored normal voltage or current.

Abstract: When it has been determined that a termination condition of brake TRC control has been fulfilled, SM valves 50FL and 50FR and a motor 80 are continuously placed in an ON state, and along with this, SR valves 70FL and 70FR are switched off, and furthermore holding valves 46FL and 46FR and pressure-reducing valves 48FL and 48FR of driving wheels are changed from an on-off switching state to an ON state, and termination control is initiated. Because of this, high-pressure brake fluid on the wheel-cylinder 2FL and 2FR side is expelled via the pressure-reducing valves 48FL and 48FR by drive of the motor 80. Consequently, high-pressure brake fluid can rapidly be expelled immediately after brake TRC control, and along with this, oil-shock noise can be alleviated.

Abstract: A hydraulic-pressure counter-force mechanism 37 which produces a counter force when a brake booster is operated is made up of an input-side member 38 slidable disposed within a valve body 3, a second constant-pressure chamber 39 formed on the rear side of the input-side member and into which a pressure is introduced from a constant pressure chamber A, and a second constant-pressure chamber 39 formed on the front side of the input-side member and into which a pressure is introduced from a variable pressure chamber B. The counter force from the hydraulic-pressure counter-force mechanism 37 is reduced by an orifice passage 43 as counter-force reducing means in rapid operation for brake.

Abstract: A counter-force mechanism (37), which produces a counter force when a brake booster is operated, is made up of an input-side member (38) slidably disposed within a valve body (3), a second constant-pressure chamber (39) formed on the rear side of the input-side member and into which a pressure is introduced from a constant pressure chamber (A), and a second constant-pressure chamber (39) formed on the front side of the input-side member and into which a pressure is introduced from a variable pressure chamber (B). The counter force from the counter-force mechanism (37) is reduced by an orifice passage (43) as a counter-force reducing means in rapid operation of the brake.

Abstract: In a brake by wire system, a linear differential pressure control valve is provided to control accurately wheel cylinder pressure. A brake fluid conduit extending from a reservoir is branched out into two conduits, each of which is transmitted to each of right and left wheel cylinders. A linear differential pressure control valve is disposed in the conduit and an another linear differential pressure control valve in each of the branched out conduits. Brake fluid sucked from the reservoir by a motor pump is discharged to each of the branched out conduits between the valve and the wheel cylinder. The two valves thus connected in series are operative step by step to control the wheel cylinder pressure in accordance with the current commanded in response to brake pedal depression.

Abstract: A fluid pressure boosting device of the present invention performs jumping action at a higher servo ratio until fluid pressure in a power chamber (25) reaches a first predetermined value and a rear end (20e) of a reaction piston (20)comes in contact with a step of an input shaft (18). Since a switching valve is set in a first position I until the fluid pressure in the power chamber (25) reaches a second predetermined pressure, a reaction chamber (41) is connected to the reservoir (33) so as to be at atmospheric pressure. In this state, the normal brake control at a lower servo ratio is performed. As the fluid pressure in the power chamber (25) reaches a second predetermined value, the switching valve is set in a second position II by the fluid pressure so that the pressurized fluid in the power chamber is introduced into the reaction chamber (41). The fluid pressure in the reaction chamber 41 acts on the step between the reaction piston (20) and the input shaft (18) so that the servo ratio becomes higher.

Abstract: A first fluid line couples first and second wheel cylinders. A second fluid line couples third and fourth wheel cylinders. A first pressure increasing unit increases pressure applied to the first and second wheel cylinders to a second pressure level which is greater than a first pressure generated by a master cylinder. When the first pressure increasing unit is in operation, a pressure difference setting unit sets a difference between pressure applied to the first and second wheel cylinders and pressure applied to the third and fourth wheel cylinders.

Abstract: In a brake boosting system the present invention, as it is decided that brake assist is necessary, a pump 53 is driven, and a solenoid valve 72 is switched to its communication position, and a solenoid shut-off valve 75 is opened. Then, the pump 53 sucks brake fluid from a reservoir 9 through the solenoid valve 72 and sends out the brake fluid to the pressure intensifying chamber 21 through the solenoid shut-off valve 75. At this point, an output shaft 11 has already advanced and a radial hole 38 is positioned ahead of a seventh cup sealing member 31 so that the pressure intensifying chamber 21 and the reaction chamber 33 are shut off from the reservoir 9 so as to be in the sealed state. Therefore, pump discharge pressure is supplied to the pressure intensifying chamber 21 and the reaction chamber 33 so that the pressure in these chambers is intensified. Since the intensified pressure acts on the primary piston 12, the master cylinder pressure is intensified to a value greater than that of normal braking.