Internal-combustion engines – Charge forming device – With fuel pump
Patent
1997-02-06
1998-01-27
Miller, Carl S.
Internal-combustion engines
Charge forming device
With fuel pump
123467, 12317917, F02M 3704
Patent
active
057112770
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to an accumulator fuel injection apparatus applied to internal combustion engines, such as a diesel engine.
BACKGROUND ART
The conventional fuel injection apparatuses for multicylinder engines include an apparatus of a fuel injection system (electronically controlled fuel injection system) in which the controlling of an injection rate and injection time is done by an electronic circuit, an apparatus of a common injection system (common-rail injection system) in which a fuel is distributed from an injection pump to combustion chambers through a common passage, and an apparatus of a pressure storage type injection system (accumulator injection system) in which a fuel is distributed from an injection pump to combustion chambers through a common passage and an accumulator. Since the fuel injection apparatuses themselves of these systems are not provided with an accumulator in which the fuel from an injection pump is temporarily stored, the supplying of the fuel to these apparatuses is done through a common rail, a common passage, i.e. an accumulator.
FIG. 8 shows an injector (which will hereinafter be referred to as a first conventional example) for a conventional accumulating fuel injection apparatus. Such a conventional injector is a pressure balancing type injector disclosed in, for example, Japanese Patent Laid-Open Nos. 165858/1984 and 282164/1987, which is formed so that a fuel is supplied to or discharged from a balancing chamber by turning on or off a solenoid valve, whereby a needle valve is seated on or lifted from a seat of the nozzle, and which is adapted to lift the needle valve from the seat by removing a needle valve closing fuel pressure applied to the interior of the balancing chamber, whereby the injection of the fuel is carried out. Such a structure will now be further described. A casing 31 of an injector 30 is provided therein with a guide bore 32, a fuel storage chamber 33 and a control volume, i.e. a balancing chamber 32. A needle valve 35 is provided slidably in the guide bore 32. The needle valve 35 comprises a larger-diameter portion 36, and a smaller-diameter portion 37 integral with the larger-diameter portion 36, and a needle 38 is provided on a lower end of the smaller-diameter portion 37. The casing 31 is provided with a hole type injection nozzle 39 (refer to FIG. 11), and the injection nozzle 39 has injection holes 40 at a lower end portion thereof. The injection nozzle 39 is also provided with a seat 41 on an inner surface of its lower end portion, and, when the needle 38 of the needle valve 35 sits on the seat 41, the injection holes 40 are closed. In the hole type injection nozzle 39, the fuel collected in a passage, which extends from the seat 41 to a combustion chamber, after the valve is closed is ejected (after-dripping) in some cases due to the high temperature and pressure variation in the combustion chamber, and the fuel becomes an unburnt gas to cause the HC in an exhaust gas to increase. Therefore, it is necessary that the volume (sack volume 49) of a space extending from the seat 41 to the injection ports 40 be set as small as possible.
The casing 31 has a supply port 42 for introducing a high-pressure fuel from an accumulating pipe (not shown) into the interior thereof, and a flow passage communicating with this supply port 42 branches into two flow passages 43, 44, one flow passage 43 communicating with the balancing chamber 34 via an orifice B, the other flow passage 44 communicating with the fuel storage chamber 33. The casing 31 further has an orifice A allowing communication of the balancing chamber 34 with the outside.
The casing 31 is provided with a solenoid valve 45 for opening and closing the orifice A. The high-pressure fuel introduced from the supply port 42 enters the balancing chamber 34 and fuel storage chamber 33 and works on the needle valve 35. When the solenoid valve 45 is in an OFF-state, the orifice A (discharge passage 46) is closed therewith. In the meantime, the high-pressure fuel is supplied to th
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Hirohisa Tanaka
Isuzu Motors Limited
Miller Carl S.
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