摘要:
An anti-lock brake system for a wheel wherein a fluid pressure is applied to a wheel cylinder, through a solenoid-operated valve device and a flow control device. Upon detection of locking of the wheel, the valve device is brought into an anti-lock state in which the valve device is alternately placed in its pressure-increase and pressure-decrease positions. The flow control device is normally placed in a first mode for a sufficient flow of the fluid into the wheel cylinder, and is operated in a second mode with the valve device placed in the anti-lock state. In the second mode, the flow control device decreases the rate of fluid flow to the wheel cylinder, with an increase in a difference between the power source pressure and the wheel cylinder pressure. An assisting device is provided for enabling the flow control device to adequaely effect the first mode of operation for at least a period between commencement of brake application and commencement of anti-lock operation of the valve device. The assisting device further assists the flow control device to adequately effect the second mode of operation at least while the valve device is in the pressure-increase position during the anti-lock operation of the valve decive.
摘要:
A braking device having a high-pressure hydraulic system including a hydraulic pressure source, a wheel-cylinder hydraulic system including a wheel cylinder for applying brake to a vehicle wheel, a low-pressure hydraulic system including a reservoir, a solenoid-operated directional control valve device for fluid communication of the wheel-cylinder hydraulic system selectively with the high-pressure hydraulic system or the low-pressure hydraulic system, an electric control device connected to the directional control valve device to control the wheel cylinder pressure, and a variable flow restrictor device disposed in the high-pressure hydraulic system or the wheel-cylinder hydraulic system, for decreasing a rate of flow of the fluid through the high-pressure or wheel-cylinder hydraulic system, with an increase in a pressure difference between the high-pressure and wheel-cylinder hydraulic systems, and with an increase in a pressure in the wheel-cylinder hydraulic system. The flow restrictor device may consist of two pilot-operated variable flow restrictor valves which may be disposed in the high-pressure and wheel-cylinder hydraulic systems, respectively, or both disposed in one of these two systems.
摘要:
A brake fluid pressure control apparatus achieves a sufficiently large brake force even when a malfunction occurs in an operational force sensor for detecting a level of operational force applied to a brake system. A magnitude of a master cylinder pressure generated by a master cylinder is detected by a master cylinder pressure sensor. A linear fluid pressure source generates a linear fluid pressure adjusted by the magnitude of the master cylinder pressure. Front wheel cylinders and rear wheel cylinders are provided with the linear fluid pressure. A front wheel cylinder pressure is detected and a front wheel cylinder pressure value corresponding to a magnitude of the front wheel cylinder pressure is output by a front wheel cylinder sensor. If it is determined that a malfunction is occurring in the operational force sensor, a connection of the front wheel cylinders is switched from the linear fluid pressure source to the master cylinder. At this time, the linear fluid pressure source is controlled based on the front wheel cylinder pressure value.
摘要:
A hydraulic brake control apparatus in which a master cylinder supplies a brake fluid pressure responsive to a brake operating force to wheel cylinders through a first valve, includes a first control unit which controls second valves and third valves when a brake fluid pressure supplied to the wheel cylinders by a pressure supplying device is detected to be excessively high under a condition in which the supply of the brake fluid pressure to the wheel cylinders by the master cylinder is inhibited by the first valve, so that the supply of the brake fluid pressure to the wheel cylinders by the pressure supplying device is inhibited by the second valves and a flow of the brake fluid from the wheel cylinders into a reservoir tank is allowed by the third valves. A second control unit controls the third valves and the first valve at a predetermined time after the flow of the brake fluid from the wheel cylinders into the reservoir tank is allowed, so that the flow of the brake fluid from the wheel cylinders into the reservoir tank is inhibited by the third valves and the supply of the brake fluid pressure to the wheel cylinders by the master cylinder is allowed by the first valve.
摘要:
When oil is discharged from an actuator 11i for lowering a vehicle height, an actuator pressure Pa is higher than a pump pressure Pp so that a differential pressure valve 41 slides its valving element 42 to the left by a pressure difference. A valving element seal portion 42b, abutted against a seat face 43a closing an opening of a lower return conduit 40b, moves from seat face 43a and open to lower return conduit 40b. As a result, the closure of the connected portion in the lower return conduit 40b is opened. Thus, the passage of a return conduit 40 is opened. Then, the oil from the actuator 11i is discharged via the return conduit 40 to the reserve tank 16 while receiving less flow resistance by avoiding a passage through any solenoid valve.
摘要:
A hydraulic brake control apparatus includes a pressure supply inhibiting unit which inhibits supply of a brake fluid pressure to wheel cylinders by a first pressure supplying unit when a defect in a brake fluid path between a first flow control unit and the wheel cylinders has occurred, and inhibits supply of a brake fluid pressure to the wheel cylinders by a second pressure supplying unit when a defect in a brake fluid path between a second flow control unit and the wheel cylinders has occurred. A pressure supply path control unit controls the first and second flow control units when a defect in one of a first brake fluid path between the first pressure supplying unit and the first flow control unit and a second brake fluid path between the second pressure supplying unit and the second flow control unit has occurred, such that a flow of the brake fluid from one of the first and second pressure supplying units connected to the defective path, into the wheel cylinders is inhibited, and a flow of the brake fluid from the other of the first and second pressure supplying units connected to the other path, into the wheel cylinders is allowed to supply the brake fluid pressure from the other pressure supplying unit to the wheel cylinders through the other path.
摘要:
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.
摘要:
In a brake fluid control device, front wheel cylinders are connected to a front hydraulic circuit, and rear wheel cylinders are connected to a rear hydraulic circuit. The front hydraulic circuit and the rear hydraulic circuit are connected to a front left pressure-decrease valve, a front right pressure-decrease valve, a rear left pressure-decrease valve, a rear right pressure-decrease valve and a connecting pipe. When a brake pedal is depressed, the front left pressure-decrease valve, the front right pressure-decrease valve, the rear left pressure-decrease valve and the rear right pressure-decrease valve are opened and a master cylinder pressure sensor leads to both the front hydraulic circuit and the rear hydraulic circuit. Comparing a detection value of the of the master cylinder pressure sensor, a detection value of a front wheel cylinder pressure sensor and a detection value of a rear wheel cylinder pressure sensor respectively, detects the state of operation of each of the sensors provided in the system.
摘要:
A hydraulic brake control apparatus in which a master cylinder is connected to wheel cylinders via a master cylinder cut valve, and the wheel cylinders are connected to a reservoir tank via a switching valve, includes a check valve provided between the master cylinder and the wheel cylinders in parallel with the master cylinder cut valve, the check valve provided in a bypass passage of the master cylinder cut valve, the check valve allowing a flow of a brake fluid from the master cylinder to the wheel cylinders and inhibiting a flow of the brake fluid from the wheel cylinders to the master cylinder. A valve control unit controls the switching valve when it is detected that a closed-position defect in the master cylinder cut valve has occurred and a pressure of the brake fluid in the master cylinder is decreasing, so that the switching valve is set at an open position to allow a flow of the brake fluid from the wheel cylinders to the reservoir tank through the switching valve and reduce a pressure of the brake fluid in the wheel cylinders.