US 5,713,315 AGranted

Multiple step valve opening control system

AssigneeMitsubishi Jidosha Kogyo Kabushiki Kaisha

InventorsHiroshi Jyoutaki, Kazutoshi Mori, Susumu Kohketsu, Yasunori Daigo, Yoshihisa Yamaki

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Abstract

A multiple step valve opening control system, particularly for an EGR control valve unit, having a plurality of valve lifts. The system comprises a valve member for opening a fluid passage in multiple steps, a first piston slidably housed in a housing, a second cylinder substantially coaxial with the first piston, a second piston fitted in the second cylinder and coupled to the valve member, and a first piston stroke regulating member which is moved selectively to a first position for regulating an allowable displacement of the first piston to a first predetermined extent (l.sub.1) or to a second position for regulating the allowable displacement of the first piston to the first predetermined first extent (l.sub.1) plus a third predetermined extent (l.sub.3). By changing the position of the first piston displacement regulating member, the valve member is opened by various valve lifts.

A multiple step valve opening control system comprising:

(a) a valve member interposed in a fluid passage, the valve member being opened by a plurality of steps for controlling a flow amount of a fluid;
(b) a first piston slidably fitted in a first cylinder disposed in a housing;
(c) a second cylinder substantially coaxially coupled to or being integral with the first piston;
(d) a second piston slidably fitted in the second cylinder and operatively coupled to the valve member;
(e) a resilient member coupled to the valve member, the resilient member continuously urging the valve member in a closing direction;
(f) a first intake/exhaust port formed in the housing, the first intake/exhaust port supplying a working medium to a first working chamber defined in the first cylinder (24), and displacing the second piston via the first piston in a direction for opening the valve member;
(g) a second intake/exhaust port formed in the housing, the second intake/exhaust port supplying the working medium to a second working chamber defined in the second cylinder, and displacing the second piston by a second predetermined extent (l.sub.2) in the direction for opening the valve member;
and
(h) a first piston stroke regulating member housed in the housing, the first piston stroke regulating member being held at a first position for regulating, to a first predetermined extent (l.sub.1), an allowable displacement of the first piston in the opening direction of the valve member when the working medium is supplied to the second working chamber from the second intake/exhaust port and to the first working chamber from the first intake/exhaust port and to the first working chamber from the first intake/exhaust port, and the first piston stroke regulating member being held at a second position for regulating the allowable displacement of the first piston in the opening direction of the valve member to the first predetermined extent (l.sub.1) with the addition of a third predetermined extent (l.sub.3), when no working medium is supplied to the second working chamber from the second intake/exhaust port but the working medium is supplied to the first working chamber from the first intake/exhaust port.

6 more elements

Abstract

Claims18