To provide a brake fluid pressure controller having excellent brake operating feeling by adjacently providing an additional valve seat part smaller in diameter than a nominal valve seat in an inner periphery of a valve seat member part.
A annular valve seat member 15 has a large diameter valve seat member 15a and a small diameter valve seat part 15b which act in common with a valve part 16a formed at one end of an hydraulic acting piston 16 in its inner periphery. The diametral part of the valve part 16a of the hydraulic acting piston 16 is provided with a brake fluid passage between its outer periphery and a cylinder 11c, and the end part of the hydraulic acting piston 16 is slidably fitted in the cylinder 11c and supported there. When brake fluid pressure exceeds the first fixed value, wheel cylinder hydraulic pressure is reduced in pressure at the first ratio smaller in a pressure reduction ratio to master cylinder hydraulic pressure. When the master cylinder hydraulic pressure arrives at the second fixed value, the wheel cylinder hydraulic pressure is reduced in pressure at the second pressure reduction ratio larger in the pressure reduction ratio to the master cylinder hydraulic pressure. Thus variation in relationship of vehicle operating force to brake operating force is made mild for making brake operating feeling excellent.
IWATA NAOKI
NOGUCHI NOBORU
