Toyota Jidosha Kogyo Kabushiki Kaisha

Aisin Seiki Kabushiki Kaisha

Takaaki Ohta

Tomoyuki Nogami

Yoshihisa Nomura

Atsushi Ohmi

Takashi Fujii

Masamoto Ando

Hiroyuki Kondo

Hiroshi Takeshita

Sadayoshi Ito

This invention relates to a hydraulic pressure control valve arrangement for automotive vehicle wheel brake systems, the latter system comprising a hydraulic master cylinder to be actuated by operating a foot brake pedal, a hydraulic brake pressure control valve assembly provided with a pneumatic servo piston mechanism, and an electromagnetic change-over valve assembly fluidically connected therewith, a skid sensor operatively connected therewith and also with a vehicle wheel, a wheel cylinder mechanism for applying hydraulic braking effort upon vehicle wheels and includes the provision for an inertia responsive valve for additionally controlling the braking fluid pressure reapplication in the wheel cylinders so as to have that reapplication be rapid at first to the fullest extent in accordance with the road coefficient and then becomes gradual.

Antiskid brake control arrangement for vehicle wheels

A proportioning valve for a hydraulic brake system having a capability of preventing brake vibration. In this proportioning valve a piston, which is exposed at one end thereof to an air chamber and constantly biased with a spring in a separating direction away from the air chamber, opens and closes a cut valve disposed in a braking fluid circuit from the master cylinder to the rear wheel cylinder(s) for performing fluid pressure regulating operation. The piston is further designed such that the stroke thereof is larger than it ought to be for the proper object, with the purpose of operating as a piston for absorbing fluid pressure vibration in the rear wheel cylinder(s) while the braking fluid pressure is relatively low, and as an ordinary fluid pressure regulating piston after the braking fluid pressure exceeds a predetermined set value.

Anti-brake-vibration type proportioning valve

A hydraulic brake booster of the type utilizing pressurized fluid supplied to a hydraulically operated device comprises a flow regulating valve adapted to rapidly increase the pressure in a power chamber of the booster in response to actuation of a control piston and another flow regulating valve adapted to ensure supply of the pressurized fluid to the hydraulically operated device. In the brake booster, the first-named valve includes an annular recess formed on the control piston for permitting the flow of fluid supplied to the power chamber when the control piston is in an original position and blocking the flow of fluid to the power chamber when the control piston is moved, and an orifice for throttling the flow of fluid supplied to the power chamber in response to movement of the control piston.

Hydraulic brake booster

A sealed type hydraulic reservoir including a casing for storing brake fluid therein, a cap member detachably mounted on the casing and an elastic diaphragm member dividing the casing into upper and lower chambers. The lower chamber is defined by the diaphragm member and the liquid surface, and the pressure in the lower chamber is always maintained at the level of atmospheric pressure by two check valves, one for allowing the air flow from the upper to the lower chamber when the pressure in the lower chamber drops below the atmospheric level and the other for allowing the air flow from the lower to upper chamber when the pressure in the lower chamber rises above the atmospheric level.

Sealed type hydraulic reservoir

A sealed type hydraulic reservoir including a check valve for normally preventing communication between a sealed chamber in which brake fluid is stored and the surrounding atmospheric environment. The check valve allows atmospheric air to flow into the sealed chamber only when the pressure in the chamber drops below atmospheric level. A second check valve may be included for allowing air flow only out of the sealed chamber when the pressure in the chamber rises above atmospheric level.

A device of the type adapted to be interposed between rear wheel brakes of a vehicle and one of dual master cylinders for separate hydraulic circuits to the front and the rear brakes, for not only sensing axle loading and weight shift in order to optimize braking effectiveness but also permitting unrestrained passage of fluid therethrough for the purpose of compensating an accidental failure of the front brakes. The device is characterized by the fact that a load sensing spring is provided for sensing the varying load on vehicle wheels in a manner such that the load sensing spring is rather less loaded in case of the failure of the front brakes than is experienced prior to the failure.

Brake proportioning means

In an inertia-controlled valve unit, a tubular stepped spool is assembled within a stepped bore of a differential piston through a coil spring. The piston is inserted together with the spool into a stepped bore of a housing in such a manner that the spool is fixed at one end thereof to an inner wall of the housing and that the piston is slidable in relation to the spool within a small diameter portion of the housing bore. The valve unit includes a ball valve housed within a large diameter portion of the housing bore and co-operating with a valve seat provided on the other end of the spool to interrupt the flow of fluid from an inlet chamber to an outlet chamber through the spool when the ball valve is subjected to a deceleration in excess of a predetermined value.

Inertia-controlled valve unit for vehicle braking systems

A brake fluid pressure control valve of a deceleration sensing type to be interposed in the hydraulic circuit, which connects, in the hydraulic braking system for a vehicle, the master cylinder and the rear wheel cylinders, with the object of effecting a proper distribution of the braking force, in response to the load degree or condition, to each of the front and rear wheels. The control valve includes a fluid passage, a first plunger for interrupting the fluid passage, and a device for controlling the operation of the first plunger, which device includes in turn a second and a third plungers to control the operation of the first plunger in accordance with the fluid pressure given from the fluid passage via a gravity valve. The third plunger constantly urges through a spring the first plunger, and the second plunger does not abut on the first plunger, while being in an empty or nonloaded state, even under a brake application, but abuts, while being in a heavy loaded state, on the first plunger so as to rigidly urges the same, in order to save the brake pedal stroke or brake oil quantity.

Brake fluid pressure control valve of a deceleration sensing type

An inertia-controlled valve unit comprises a differential piston slidable within a stepped bore of a housing to provide first and second fluid chambers respectively in open communication with inlet and outlet ports of the housing, the piston being exposed at the smaller end thereof in the first chamber and at the larger end thereof in the second chamber. The valve unit further comprises a tubular spool slidable within an axial bore of the piston and having one end fixedly engaged with the inner wall of the housing in the second chamber and the other end exposed in the first chamber, the spool including an axial passage permitting fluid flows between the first and second chambers, and a cut-off valve including a valve seat provided on the other end of the spool and an inertia-controlled ball located within the first chamber to co-operate with the valve seat and rolling toward the valve seat to cut-off fluid flow from the first chamber to the second chamber when the ball is subjected to a deceleration in excess of a predetermined value.

Fluid pressure control valve for vehicle braking systems

The control apparatus comprises a housing having first and second hydraulic pressure chambers formed therein and communicated to each other through a communication passage. The first hydraulic pressure chamber is hydraulically communicated with a master cylinder actuated by a brake pedal of the vehicle, while the second chamber is hydraulically communicated with the rear wheel brake cylinders. A differential piston is axially movably disposed within the housing and having one end portion exposed to the first hydraulic pressure chamber and the other end portion projecting into the second hydraulic pressure chamber. The effective area of the differential piston subjected to the hydraulic pressure is made smaller at the one end portion thereof located in the first pressure chamber than at the other end portion located in the second pressure chamber by forming a sealed air chamber adjacent to the first pressure chamber between the inner wall of the differential piston and a stationary sleeve on which the piston is movably supported. An inertia valve member is disposed in the first hydraulic pressure chamber and adapted to close the communication passage when deceleration of the vehicle attains a predetermined value.

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Okazaki, Japan

Takaaki Ohta