US 6,581,553 B2Granted

Two-stroke engine

AssigneeFuji Jukogyo Kabushiki Kaisha

InventorsKoji Morikawa, Hideharu Takimoto, Yasuo Moriyoshi

Life of this patent

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Abstract

In a two-stroke engine, fresh air introduced through a scavenging port into a combustion chamber becomes an air flow directed to a top surface of a piston and is guided by a concave of the piston top surface to produce an reverse tumble flow. A combustion gas is pushed out through an exhaust port, opened and closed by the piston, in a stratified state by the scavenging flow. In addition, when the exhaust port goes down in the closure condition, a strong tumble flow occurs in the combustion chamber , and at an ignition position(point, location) in the vicinity of the top dead center, the reverse tumble flow runs against a squish developing between the piston top surface and a lower surface of a cylinder head and gathers in the concave in a state disturbed.

Claims13

Dependent claims

A two-stroke engine comprising:

a cylinder block defining a cylinder;
a piston reciprocally movable within said cylinder;
a cylinder head which together with said piston and said cylinder defines a combustion chamber;
an in-cylinder injector provided in said cylinder head;
a curved concave formed on a top surface of said piston;
at least one scavenging port including a first scavenging port which extends toward an inner side wall of said cylinder at a first side with respect to a reference plane passing through a center axis of said cylinder, and which is formed in said cylinder head to have an opening end adapted to be opened to said combustion chamber at said first side with respect to said reference plane for generating a tumble flow toward the top surface of said piston;
and
an exhaust port formed in said cylinder block to be opened to said cylinder at a second side with respect to said reference plane in accordance with reciprocal movement of said piston;
wherein injection timing of said in-cylinder injector is set such that a mist flow emitted from said in-cylinder injector arrives at a slightly inner side of an outer edge of said curved concave of said piston when said piston closes said exhaust port at an earliest injection timing.

6 more elements

Dependencies are inferred from the claim text.

Facts

Application: 09/884,590Filed 19 Jun 2001
Priority: JP 2000-18988823 Jun 2000
Published: US 2001/0054398 A127 Dec 2001
Granted: 24 Jun 2003
Term ends: Not estimatedThe source records don’t support an estimate.

Classification12 codes

F02B 25/04
Using unidirectional scavenging: engines having ports both in cylinder head and in cylinder wall near bottom of piston stroke
F02B 23/104
With separate admission of air and fuel into cylinder: the injector being placed on a side position of the cylinder
F02B 31/00
Modifying induction systems for imparting a rotation to the charge in the
F02B 2023/107
Tumble flow, i.e. the axis of rotation of the main charge flow motion is horizontal: reverse tumble flow, e.g. having substantially vertical…