Patent ID: 7784493

Claim:
A manual valve of a hydraulic pressure control system for an automatic transmission of a vehicle, comprising: a valve body comprising a first exhaust passage that comprises an exhausting hole and an intake hole, wherein the holes communicate with a drive range port when the vehicle is in a neutral range, such that a transmission fluid, supplied from the drive range port when the vehicle is shifted from a drive range to the neutral range, is exhausted; and a hydraulic pressure exhaust control unit that is disposed in the exhaust hole and controls an exhaust amount according to an exhaust pressure, wherein the exhaust hole comprises a small diameter portion, a middle diameter portion, and a large diameter portion, the small diameter portion being disposed nearest the intake hole and the large diameter portion being disposed farthest from the intake hole while the large diameter portion has a drain hole; and wherein the hydraulic pressure exhaust control unit comprises: a slider that slides along the middle diameter portion by the exhaust pressure; and at least one main hole that communicates with the drain hole according to a position of the slider, wherein the slider is substantially cylindrical and comprises an open surface portion at a first end of the slider, which faces the intake hole; and a closed surface portion disposed at a second end of the slider, wherein the at least one main hole comprises an orifice disposed on the closed surface portion of the slider, and a penetration hole disposed on a circumference of the slider, and wherein a diameter of the penetration hole is larger than a diameter of the orifice, and the intake hole, the penetration hole and the orifice are fluidly connected each other to the drain hole to form a continuous flow passage between the intake hole and the drain hole through the orifice.