Combustion Chamber Shape of Direct Injection Type Diesel Engine

• US 20070272191A1
• Filed: 05/25/2005
• Published: 11/29/2007
• Est. Priority Date: 07/09/2004
• Status: Active Grant

• Current Assignee: Yanmar Power Technology Co., Ltd.
• Original Assignee: Yanmar Company Limited (Yanmar Holdings Co., Ltd.)
• Inventors: Hamaoka, Shunji, Tsujimoto, Keiichi
• Granted Patent: US 7,472,678 B2
• Time in Patent Office: Days
• US Class Current: 123/193.500
• CPC Class Codes: F02B 23/0651 the fuel spray impinging on reflecting surfaces or being specially guided throughout the combustion space
• CPC Class Codes: F02B 23/0669 having multiple fuel spray jets per injector nozzle
• CPC Class Codes: F02B 23/0696 W-piston bowl, i.e. the combustion space having a central projection pointing towards the cylinder head and the surrounding wall being inclined towards the cylinder wall
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies

Abstract

An object of the present invention is to provide a combustion chamber shape of a direct injection type diesel engine in which a black smoke generation amount can be suppressed during no-load operation while suppressing NOx and fuel consumption. The combustion chamber 5 is formed in a recessed shape in a piston top wall 3 and injecting fuel at a predetermined nozzle hole angle α into the combustion chamber 5 from a nozzle hole 20 of a fuel injection valve having a nozzle hole center O1 substantially on a cylinder center line. A wall face of the combustion chamber 5 includes: a conical mountain portion 12 formed at a central portion in the combustion chamber and having such a slope angle and skirt end diameter D2 that fuel spray does not collide with the mountain portion; a slope portion 14 that inclines downward and outward from a skirt end of the mountain portion 12 at a smaller angle than the slope angle of the mountain portion 12 and with which the fuel spray collides; and a saucer portion 15 which rises in an arc shape from an outer peripheral end of the slope portion 14 to reach an outer peripheral end of the combustion chamber and with which the fuel spray collides.

Claims

1. A combustion chamber shape of a direct injection type diesel engine having a combustion chamber formed in a recessed shape in a piston top wall and injecting fuel at a predetermined nozzle hole angle into the combustion chamber from a nozzle hole of a fuel injection valve having a nozzle hole center substantially on a cylinder center line,

wherein a wall face of the combustion chamber includes:

a conical mountain portion formed at a central portion in the combustion chamber and having such a slope angle and skirt end diameter that fuel spray does not collide with the mountain portion;

a slope portion that inclines downward and outward from a skirt end of the mountain portion at a smaller angle than the slope angle of the mountain portion and with which the fuel spray collides; and

a saucer portion which rises in an arc shape from an outer peripheral end of the slope portion to reach an outer peripheral end of the combustion chamber and with which the fuel spray collides.

2. A combustion chamber shape of a direct injection type diesel engine according to claim 1,

wherein, in the mountain portion, a ratio H2/H1 of a mountain portion height H2 from a combustion chamber bottom face to a combustion chamber depth H1 is 0.7≦

H2/H1≦

1.0,

a ratio D1/B of a diameter D1 of a mountain portion top face to a bore diameter B is D1/B≦

0.3, and

a ratio D2/B of a diameter D2 of the skirt end of the mountain portion to the bore diameter B is D2/B≦

0.5.

3. A combustion chamber shape of a direct injection type diesel engine according to claim 1, wherein a ratio L/d of a spray travel L to a nozzle hole diameter d is 150≦

L/d≦

250.

4. A combustion chamber shape of a direct injection type diesel engine according to claim 1, wherein the slope angle 0 of the slope portion is 0°

≦

θ

≦

15°

.