Vehicle braking control apparatus

A vehicle braking control apparatus, comprising:

• fluid pressure generation means for generating fluid pressure corresponding to a vehicle braking operation;
• a braking mechanism provided for each wheel of the vehicle and to which is supplied fluid pressure from said fluid pressure generation means for applying a braking force to each wheel corresponding to this fluid pressure, said braking mechanism comprising a wheel cylinder which has a hydraulic chamber and supplies fluid pressure from said fluid pressure generation means, a brake piston provided inside said wheel cylinder for applying a braking force on the wheel by fluid pressure in said hydraulic chamber and a control valve provided in a passage for supplying fluid pressure to said wheel cylinder from said fluid pressure generation means to open and close this passage;
• a piezoelectric piston device constructed of a plurality of laminated piezoelectric elements for expanding and contracting to vary the volume of a hydraulic chamber of said wheel cylinder by the application of a voltage,
• a displacement amplifying mechanism which is driven by changes in the volume of said hydraulic chamber to amplify expansion and contraction of said piezoelectric piston device,
• a displacement member which is provided in said wheel cylinder and which is driven in response to the displacement of said displacement amplifying means to vary the volume inside said wheel cylinder, and
• a control means for applying voltage to said piezoelectric piston device with said fluid passage closed by said control valve and during said displacement member to vary the fluid pressure inside said wheel cylinder.

A vehicle braking control apparatus, comprising:

• a wheel cylinder formed in each brake caliper provided for each wheel of the vehicle;
• a brake piston provided in said wheel cylinder and driven by the fluid pressure in said wheel cylinder to apply a corresponding braking force to the wheel;
• a piezoelectric piston device, which is constructed of a plurality of laminated plate-shaped piezoelectric elements and is combined with said brake piston to vary the volume of said brake piston by expanding and contracting said piezoelectric elements by the application of voltage;
• fluid supplying means for supplying fluid to said wheel cylinder;
• a control valve formed in said brake caliper near said wheel cylinder for opening and closing a fluid passage connected to said wheel cylinder;
• command signal generation means for generating braking command signals based on a signal from a braking signal generation means;
• and
• control means for causing said control valve to close said fluid passage based on a braking command signal from said command signal generation means, expanding and contracting said piezoelectric piston device by varying the voltage applied to the piezoelectric elements that comprise said piezoelectric piston device to vary the volume of said brake piston such that said brake piston moves within said wheel cylinder.

A vehicle braking control apparatus, comprising:

• a wheel cylinder formed in each brake caliper provided for each wheel of the vehicle;
• a brake piston movably provided in said wheel cylinder to apply a braking force to the wheel corresponding to the pressure rise inside said wheel cylinder;
• a guide cylinder which is provided in said brake caliper coaxial with said wheel cylinder with a wall partitioning off said wheel cylinder and said guide cylinder;
• a housing, which is movable along the axis of said wheel cylinder in said guide cylinder and which has a control cylinder formed inside;
• a piezoelectric piston device, which comprises a plurality of laminated plate-shaped piezoelectric elements and which forms a hydraulic chamber in said control piston in said housing, for varying the volume of said fluid chamber in said control cylinder by expanding and contracting said piezoelectric elements by the application of voltage;
• a displacement member which is driven by changes in volume of the hydraulic chamber in said control cylinder;
• a shaft, which passes through said wall partitioning said wheel cylinder and said guide cylinder and couples said displacement member and said brake piston;
• coupling means for selectively coupling said housing to said guide cylinder;
• and
• control means for expanding and contracting said piezoelectric piston device by application of voltage with said housing coupled by said coupling means inside said guide cylinder, and driving said displacement member to vary the braking force of said brake piston.