Braking system having valve device for delivering pressurized fluid to brake cylinder selectively from at least two pressurizing chambers or only one of them

A braking system comprising:

• a master cylinder including a housing, and a pressurizing piston which is fluid-tightly and slidably fitted in said housing and which is operatively connected to a manually operable brake operating member, said pressurizing piston cooperating with said housing to define a pressurizing chamber and a rear pressure chamber on respective front and rear sides thereof;
• a brake cylinder connected to said pressurizing chamber;
• an assisting cylinder including a housing, and an assisting piston fluid-tightly and slidably fitted in said housing and cooperating with said housing to define an assisting chamber in front of said assisting piston, said assisting chamber being connected to said brake cylinder and said master cylinder such that said assisting chamber is located between said brake cylinder and said master cylinder;
• a master-cylinder cut-off valve disposed between said assisting chamber and said pressurizing chamber, and having an open state in which said assisting chamber and said pressurizing chamber are communicated with each other, and a closed state in which said assisting chamber and said pressurizing chamber are isolated from each other;
• a stroke simulating device operable to permit flows of a working fluid between said stroke simulating device and said pressurizing chamber according to a movement of said pressurizing piston while said master-cylinder cut-off valve is placed in said closed state, such that said stroke simulating device applies to said pressurizing piston a reaction force which corresponds to a pressure of the fluid in said pressurizing chamber;
• and
• a braking characteristic control device operable to control a pressure of the fluid in said rear pressure chamber and the pressure of the fluid in said assisting chamber, for thereby controlling braking characteristics of the braking system,
• and wherein said braking characteristic control device comprises:
• a first control portion operable while said master-cylinder cut-off valve is placed in said closed state, to control the pressure of the fluid in said rear pressure chamber on the basis of an operating stroke of said brake operating member, and control the pressure of the fluid in said assisting chamber on the basis of an operating force of said brake operating member;
• and
• a second control portion operable while said master-cylinder cut-off valve is placed in said open state, to control the pressure of the rear pressure chamber on the basis of said operating force, and control the pressure of the fluid in said assisting chamber on the basis of said operating stroke.

A braking system comprising:

• a master cylinder including a pressurizing piston which is operatively connected to a manually operable brake operating member and which defines a pressurizing chamber and a rear pressure chamber on respective front and rear sides thereof;
• a brake cylinder connected to said pressurizing chamber;
• an assisting cylinder including a housing, and an assisting piston fluid-tightly and slidably fitted in said housing and cooperating with said housing to define an assisting chamber and an assisting rear pressure chamber on respective front and rear sides thereof, said assisting chamber being connected to said brake cylinder and said master cylinder such that said assisting chamber is located between said brake cylinder and said master cylinder wherein said assisting cylinder being operated according to the pressure of the fluid in said assisting rear pressure chamber;
• a master-cylinder cut-off valve disposed between said assisting chamber and said pressurizing chamber, and having an open state in which said assisting chamber and said pressurizing chambers are communicated with each other, and a closed state in which said assisting chamber and said pressurizing chamber are isolated from each other;
• a braking characteristic control device operable to control at least one of a pressure of the fluid in said rear pressure chamber of said master cylinder and a pressure of the fluid said assisting rear pressure chamber, for thereby controlling braking characteristics of the braking system;
• and
• a hydraulic pressure source operable to deliver a pressurized fluid used commonly for said rear pressure chamber of said master cylinder and said assisting rear pressure chamber of said assisting cylinder,
• and wherein said braking characteristic control device includes a ratio control portion operable while said master-cylinder cut-off valve is placed in said closed state, to control a ratio of a rate of flow of the pressurized fluid from said hydraulic pressure source to said assisting rear pressure chamber of said assisting chamber, to a rate of flow of the pressurized fluid from said hydraulic pressure source to said rear pressure chamber of said master cylinder.

A braking system comprising:

• a manual pressure-generating system including a manually operable brake operating member, and a master cylinder including a pressurizing piston which is operatively connected to said manually operable brake operating member and which defines a pressurizing chamber and a rear pressure chamber on respective front and rear sides thereof;
• a brake cylinder connected to said pressurizing chamber;
• an assisting cylinder including a housing, and an assisting piston fluid-tightly fitted in said housing and cooperating with said housing to define an assisting chamber and an assisting rear pressure chamber on respective front and rear sides thereof, said assisting chamber being connected to said brake cylinder and said pressurizing chamber of said master cylinder, said assisting cylinder being operated according to a pressure of the fluid in said assisting rear pressure chamber;
• a master-cylinder cut-off valve disposed between said assisting chamber and said pressurizing chamber, and having an open state in which said assisting chamber and said pressurizing chamber are communicated with each other, and a closed state in which said assisting chamber and said pressurizing chamber are isolated from each other;
• a braking characteristic control device operable to control a pressure of the fluid in said rear pressure chamber of said master cylinder, and the pressure of the fluid in said assisting rear pressure chamber, for thereby controlling braking characteristics of the braking system;
• and
• a diagnosing device operable while said master-cylinder cut-off valve is in said closed state, to diagnose said manual-pressure-generating system on the basis of a relationship between an operating state of said manually operable brake operating member and the pressure of the fluid in said pressurizing chamber of said master cylinder,
• and wherein said braking characteristic control device is operated with said master-cylinder cut-off valve held in said open state when said diagnosing device determines that said manual-pressure-generating system is normally operable.

A braking system comprising:

• a master cylinder including a pressurizing piston which is operatively connected to a manually operable brake operating member and which defines a pressurizing chamber on a front side thereof;
• a brake-cylinder activating system including (a) a brake cylinder connected to said pressurizing chamber, and (b) an assisting cylinder including a housing, and an assisting piston fluid-tightly and slidably fitted in said housing and cooperating with said housing to define an assisting chamber and an assisting rear pressure chamber on respective front and rear sides thereof, said assisting chamber being connected to said brake cylinder and said master cylinder such that said assisting chamber is located between said brake cylinder and said master cylinder, said assisting cylinder being operated according to a pressure of a working fluid in said assisting rear pressure chamber;
• a master-cylinder cut-off valve disposed between said assisting chamber and said pressurizing chamber, and having an open state in which said assisting chamber and said pressurizing chamber are communicated with each other, and a closed state in which said assisting chamber and said pressurizing chamber are isolated from each other;
• a braking characteristic control device operable to control a pressure of the fluid in said assisting rear pressure chamber, for thereby controlling braking characteristics of the braking system;
• and
• a diagnosing device operable, while said master-cylinder cut-off valve is in said closed state, to diagnose said brake-cylinder activating system on the basis of a relationship between the pressure of the fluid in said brake cylinder and an operating state of said assisting cylinder.

A braking system comprising:

• a brake operating member manually operable by an operator of the braking system;
• a master cylinder operable upon an operation of said brake operating member and including a housing, and at least two pressurizing pistons which are fluid-tightly and slidably fitted in said housing and which cooperate with said housing to define at least two pressurizing chambers which are isolated from each other, and wherein a working fluid in each of said at least two pressurizing chambers is pressurized by an advancing movement of a corresponding one of said at least two pressurizing pistons;
• a hydraulically operable brake cylinder for activating a brake;
• and
• a valve device having a first state in which the pressurized fluid is delivered from two pressurizing chambers of said at least two pressurizing chambers to said brake cylinder, and a second state in which the pressurized fluid is delivered from only one of said two pressurizing chambers to said brake cylinder, wherein:
• the braking system is structured such that when the at least two pressurizing pistons move relative to the housing while the valve device is in the second state, the fluid is permitted to be discharged from the only one of said two pressurizing chambers and delivered to the brake cylinder, but none of the fluid permitted to be discharged from the other of the two pressurizing chambers is permitted to be delivered to said brake cylinder,
• the braking system is structured to have the first state and the second state in a normal braking operation in which the pressure of the pressurized fluid in the brake cylinder changes with an amount of operation of the brake operating member, and
• said master cylinder has a rear pressure chamber partially defined by a rear surface of one of said at least two pressurizing pistons, said braking system further comprising a master-cylinder pressure control device operable to control a pressure of the fluid in said rear pressure chamber of said master cylinder.

A braking system comprising:

• a brake operating member manually operable by an operator of the braking system;
• a master cylinder operable upon an operation of said brake operating member and including a housing, and at least two pressurizing pistons which are fluid-tightly and slidably fitted in said housing and which cooperate with said housing to define at least two pressurizing chambers which are isolated from each other, and wherein a working fluid in each of said at least two pressurizing chambers is pressurized by an advancing movement of a corresponding one of said at least two pressurizing pistons;
• a hydraulically operable brake cylinder for activating a brake;
• a valve device having a first state in which the pressurized fluid is delivered from two pressurizing chambers of said at least two pressurizing chambers to said brake cylinder, and a second state in which the pressurized fluid is delivered from only one of said two pressurizing chambers to said brake cylinder;
• an assisting pressure control device disposed between said master cylinder and said brake cylinder and operable to control the pressure of the fluid in said brake cylinder such that the pressure of the fluid in said brake cylinder is higher than that of the fluid in said master cylinder;
• and
• a braking-pressure control valve device disposed between said assisting cylinder and said brake cylinder, wherein:
• the braking system is structured such that when the at least two pressurizing pistons move relative to the housing while the valve device is in the second state, the fluid is permitted to be discharged from the only one of said two pressurizing chambers and delivered to the brake cylinder, but none of the fluid permitted to be discharged from the other of the two pressurizing chambers is permitted to be delivered to said brake cylinder, and
• the braking system is structured to have the first state and the second state in a normal braking operation in which the pressure of the pressurized fluid in the brake cylinder changes with an amount of operation of the brake operating member.