Diesel engine

Details Diesel engine Diesel engine

2000-06-09

2001-12-25

Solis, Erick (Department: 3748)

Internal-combustion engines

Combustion chamber means having fuel injection only

Using multiple injectors or injections

C123S339250

Reexamination Certificate

active

06332447

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to a diesel engine which reduces noise and vibration, and especially during idle running of an engine.
BACKGROUND OF THE INVENTION
In a conventional diesel engine, the maximum internal cylinder pressure (i.e., the maximum generated pressure in a cylinder) is at a very high level, the maximum internal cylinder pressure, particularly in the idle state, is far higher than in a gasoline engine with a throttle in an intake system (“Isuzu Technical Papers”, Vol. 99, p. 85).
As a result, for the same difference of engine torque fluctuation and vibration, the noise and vibration of a diesel engine are very marked in comparison to a gasoline engine in the idle state.
A technique for reducing noise in the idle running state of a diesel engine is disclosed in Japanese Patent Publication Tokkai Sho 56-101031. In this invention, a shutter is provided in an intake air passage of the engine, this shutter being closed in the idle running state. This reduces the intake air amount and decreases the pressure in the compression stroke. By decreasing the compression pressure, the maximum pressure generated when fuel is burnt also decreases, so noise in the idle running state is therefore mitigated.
SUMMARY OF THE INVENTION
This noise reduction effect increases the more the intake air amount is reduced. However, if the intake air amount is reduced, the gas temperature in the cylinder compressed in the compression stroke also falls, so the ignitability of the fuel injected near the end of the compression stroke is impaired and the combustion stability is thereafter adversely affected.
It is therefore an object of the present invention to resolve the above problem by reducing noise and vibration without impairing combustion in the idle running state.
In order to achieve the above object, the present invention provides a diesel engine which comprises a piston having a dish-shaped combustion chamber is formed on its top surface, a fuel injector situated coaxially with the combustion chamber which injects fuel directly into a cylinder, an intake air amount control device which varies an intake air amount aspirated by the engine, and a detector which detects a running state of the engine. The diesel engine further comprises a mechanism for determining whether or not the engine is an idle running state or a normal running state, a mechanism for controlling the intake air amount controller based on the engine running state so that the intake air amount in the idle running state is less than the intake air amount in the normal running state, and a mechanism for controlling the fuel injector so that part of the fuel is injected before a main injection when the engine is in the idle running state.
The details as well as other features and advantages of the present invention are set forth in the remainder of the specification and are shown in the accompanying drawings.


REFERENCES:
patent: 5492098 (1996-02-01), Hafner et al.
patent: 6032642 (2000-03-01), Trumbower et al.
patent: 6067489 (2000-05-01), Letang et al.
patent: 6161519 (2000-12-01), Kimura et al.
patent: 6240896 (2001-06-01), Ueda et al.
patent: 56-101031 (1981-08-01), None
patent: 7-4287 (1995-01-01), None
Nakada T., “Recent trend in noise and vibration reduction technologies and diesel engines”, Isuzu Technical Papers, vol. 99, pp. 85-91, 1998.

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