| 摘要 |
<p>PURPOSE:To surely prevent a valve from sticking by a method wherein the form and dimensions of a spool is set to have specified relationships to an inlet port an outlet port, and a drain port in a constant pressure valve most suitable for the hydraulic control device of a vehicular automatic transmission. CONSTITUTION:A constant pressure valve consists in slidably housing a spool 4, which has a first land 6 to open and close an inlet port 1 and a second land 7 with the diameter larger than that of the land 6 to adjust the amount of oil discharged from a drain port 5, in a bore, within which the inlet port 1, the outlet port 2, and the drain port 3 are provided, and energizing said spool 4 downwards by means of a spring 5. In this case, the drain port 3 is covered by the second land 7 at all times and the discharge of pressure oil through said port 3 is contrived to be performed through a clearance between the outer peripheral wall of the second land 7 and the inner peripheral wall of the bore. Furthermore, the increase and decrease of the amount of said discharged oil can be controlled by changing the distance L laying between the end of the second land 7 and the end of the drain port 3.</p> |
