Internal-combustion engines – Combustion chamber means having fuel injection only – Using multiple injectors or injections
Reexamination Certificate
2001-11-14
2003-09-23
Vo, Hieu T. (Department: 3747)
Internal-combustion engines
Combustion chamber means having fuel injection only
Using multiple injectors or injections
C123S501000, C123S480000, C123S490000
Reexamination Certificate
active
06622692
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATION
This application corresponds to Japanese Patent Application No. 2000-069993 filed in JPO on Mar. 14, 2000, the entire disclosure of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a common rail fuel injection device for injecting, via injectors, pressurized fuel accumulated in a common rail, and more particularly to a common rail fuel injection device for performing fuel injection by means of a main injection and a pilot injection by which a small quantity of fuel is injected prior to the main injection.
2. Description of the Related Art
In the prior art, a common rail fuel injection system is known as a method for obtaining a high fuel injection pressure in a fuel injection system for an engine, and as a method for optimally controlling fuel injection conditions such as the injection time point and injection quantity, in accordance with the operating state of the engine. A common rail fuel injection system is a system in which an pressurized operating fluid raised to a prescribed pressure by means of a fuel supply pump is accumulated inside a common rail, the accumulated operating fluid is supplied to injectors, and fuel is injected into from the injectors disposed respectively on a plurality of associated cylinders, under optimal fuel injection conditions such as fuel injection quantity and fuel injection time which are determined by a controller in accordance with the operating state of the engine. Each injector is provided with a control valve for controlling passing or cutoff of fuel which is supplied via a fuel supply pipe.
If the fuel itself forms the operating fluid, then the common rail accumulates pressurized fuel therein, and a fuel pressure corresponding to the injection pressure is exerted constantly in a fuel supply path formed from the common rail, via fuel supply pipes, to nozzles formed at the front end of each injector. In order that each injector can only inject fuel at prescribed time, each injector includes, as a control valve, an open/close valve for opening and shutting the fuel supply path. The open/close valve is driven by an actuator which is constituted by an electromagnetic solenoid, piezoelectric element, magnetic distortion element, or the like. The controller controls the pressure in the common rail and the operation of the control valves of the injectors, in such a manner that the pressurized fuel is injected by each injector at optimal injection conditions with respect to the operating state of the engine.
In a common rail fuel injection device, the open/close valves are, for example, electromagnetic valves, such as electromagnetic solenoids, operated by electromagnetically activated actuators, on the basis of electrical signals output by the controller. With regard to the fuel injection quantity, the controller determines a target fuel injection quantity in accordance with the operating state of the engine, and controls the time at which the injector actuators are operated on the basis of the target fuel injection quantity thus determined. If the actuators are electromagnetic valves, then this involves controlling the length of the time for which the electromagnetic valve opens, in other words, the pulse time length of the injection command pulse output by the controller to the electromagnetic valve. However, since the amount of fuel injected per unit time, in other words, the fuel injection rate, depends not only on the pulse duration but also the fuel pressure in the common rail, the pulse time is determined with respect to both the target fuel injection quantity and the common rail fuel pressure.
FIG. 5
shows an overview of a common rail fuel injection system in which a common rail fuel injection device is applied. The common rail fuel injection system
1
illustrated as shown in
FIG. 1
is a system for a six-cylinder engine, in which fuel in a fuel tank
4
is passed through a pre-filter
5
and a filter
6
including a circulating valve and demoisturizer, then travels along a fuel pipe
7
, and is supplied to a fuel supply pump
8
which is, for example, a variable capacity high-pressure plunger-type pump. The fuel supply pump
8
is driven by the engine output, and raises the fuel pressure to a prescribed pressure required, and supplies the fuel to a common rail
2
, via a fuel pipe
9
and a pressure control valve
11
. On the outlet side of the fuel supply pipe
8
and the inlet side of the common rail
2
, the pressure control valve
11
is provided in order to maintain the fuel pressure in the common rail
2
at a prescribed pressure. Fuel relieved from the fuel supply pump
8
is returned via a return pipe
12
to the fuel tank
4
. The fuel inside the common rail
2
is supplied to a plurality of injectors
10
(only one injector is depicted here) via a fuel supply pipe
3
. Of the fuel that is supplied to the injectors
10
via the fuel supply pipe, fuel which is not consumed in injection into a combustion chamber, and the fuel which is relieved by the pressure control valve
11
is returned to the fuel tank
4
by means of return pipes
13
and
14
.
The controller
15
is an electronic control unit which inputs signals from various sensors
16
for detecting the operating state of the engine, for instance, an engine cylinder discriminating sensor, a crank angle sensor for detecting the number of the engine revolution Ne and the top dead center (TDC), an accelerator opening sensor for detecting the depression amount of the accelerator pedal Ac, a water temperature sensor for detecting the temperature of the cooling water, an intake tube pressure sensor for detecting the internal pressure of the intake tube, and the like. The pressure of the common rail
2
is detected by a pressure sensor
18
provided at the pressure control valve
11
, and a detection signal for the fuel pressure Pr inside the common rail
2
(hereinafter, the common rail pressure is called Pr) detected by the pressure sensor
18
is also input to the controller
15
. On the basis of these signals, the controller
15
controls the injection conditions for the fuel from the injectors
10
, in other words, the fuel injection time (injection start time point and duration), injection quantity and the like such that the engine output is optimally suited to the engine operating state. As the injectors
10
inject fuel, the fuel in the common rail
2
is consumed and the fuel pressure inside the common rail falls. However, the controller
15
controls this common rail pressure Pr by controlling the pressure of the high-pressure fuel from the fuel supply pump
8
by means of a control unit
19
of the pressure control valve
11
, in such a manner that the common rail pressure Pr remains constant, or in such a manner that the fuel injection pressure required according to the operating state of the engine is achieved.
FIG. 6
is an approximate longitudinal sectional view showing one example of an injector used in a common rail fuel injection system. The injector
10
is installed in a sealed state by means of a sealing member in a cavity portion provided in the base of the cylinder head, or the like (not illustrated). The fuel supply pipe
3
is connected to the upper side portion of the injector
10
, and a fuel supply path is formed by this fuel supply pipe
3
, and fuel passages
21
,
22
formed inside main body of the injector
10
. Fuel supplied via this fuel path travels via a fuel reservoir
23
and paths around a needle valve
24
, and is injected into a combustion chamber from a nozzle
25
formed at the front end portion of the injector
10
. The nozzle
25
opens when the needle valve
24
lifts open.
In order to control the lifting of the needle valve
24
, the injector
10
is provided with a needle lifting mechanism based on a balance chamber method. An electromagnetic actuator
26
for driving an electromagnetic valve is provided on the uppermost portion of the injector
10
, and a control current corresponding to a command pulse fro
Huynh Hai H
Isuzu Motors Limited
McCormick Paulding & Huber LLP
Vo Hieu T.
LandOfFree
Common rail fuel injection device does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Common rail fuel injection device, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Common rail fuel injection device will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3095828