Dual control valve

Details Dual control valve Dual control valve

2002-03-25

2004-06-08

Hwu, Davis (Department: 3752)

Fluid sprinkling, spraying, and diffusing

Including valve means in flow line

Reciprocating

C239S088000, C239S585300, C239S585500, C239S533800, C239S533900

Reexamination Certificate

active

06745958

ABSTRACT:

TECHNICAL FIELD
The present application relates to internal combustion engine valve control. More particularly, the present application relates to needle valve control in a fuel injector and to camless control of engine intake/exhaust valves.
BACKGROUND AND PRIOR ART
Referring to the prior art drawings,
FIG. 1
shows a prior art fuel injector
50
. The prior art injector
50
is substantially as described in U.S. Pat. No. 5,460,329 to Sturman. A fuel injector having certain similar features may be found in U.S. Pat. No. 5,682,858 to Chen et al, The fuel injector
50
is typically mounted to an engine block and injects a controlled pressurized volume of fuel into a combustion chamber (not shown). The injector
50
is typically used to inject diesel fuel into a compression ignition engine, although it is to be understood that the injector could also be used in a spark ignition engine or any other system that requires the injection of a fluid.
The fuel injector
50
has an injector housing
52
that is typically constructed from a plurality of individual parts. The housing
52
includes an outer casing
54
that contains block members
56
,
58
, and
60
. The outer casing
54
has a fuel port
64
that is coupled to a fuel pressure chamber
66
by a fuel passage
68
. A first check valve
70
is located within fuel passage
68
to prevent a reverse flow of fuel from the pressure chamber
66
to the fuel port
64
. The pressure chamber
66
is coupled to a nozzle chamber
304
and to a nozzle
72
by means of fuel passage
74
. A second check valve
76
is located within the fuel passage
74
to prevent a reverse flow of fuel from the nozzle
72
and the nozzle chamber
304
to the pressure chamber
66
. The flow of fuel through the nozzle
72
is controlled by a needle valve
78
that is biased into a closed position by spring
80
located within a spring chamber
81
. The needle valve
78
has a shoulder
82
in the nozzle chamber
304
above the location where the passage
74
enters the nozzle
78
. When fuel flows in the passage
74
, the pressure of the fuel applies a force on the shoulder
82
in the nozzle chamber
304
. The shoulder force acts to overcome the bias of spring
80
and lifts the needle valve
78
away from the nozzle
72
, allowing fuel to be discharged from the injector
50
.
A passage
83
may be provided between the spring chamber
81
and the fuel passage
68
to drain any fuel that leaks into the chamber
81
. The drain passage
83
prevents the build up of a hydrostatic pressure within the chamber
81
which could create a counteractive force on the needle valve
78
and degrade the performance of the injector
50
.
The volume of the pressure chamber
66
is defined in part by an intensifier piston
84
. The intensifier piston
84
extends through a bore
86
of block
60
and into a first intensifier chamber
88
located within an upper valve block
90
. The piston
84
includes a shaft member
92
which has a shoulder
94
that is attached to a head member
96
. The shoulder
94
is retained in position by clamp
98
that fits within a corresponding groove
100
in the head member
96
. The head member
96
has a cavity which defines a second intensifier chamber
102
.
The first intensifier chamber
88
is in fluid communication with a first intensifier passage
104
that extends through block
90
. Likewise, the second intensifier chamber
102
is in fluid communication with a second intensifier passage
106
.
The block
90
also has a supply working passage
108
that is in fluid communication with a supply working port
110
. The supply working port
110
is typically coupled to a system that supplies a working fluid which is used to control the movement of the intensifier piston
84
. The working fluid is typically a hydraulic fluid, preferably engine lubricating oil, that circulates in a closed system separate from fuel. Alternatively the fuel could also be used as the working fluid. Both the outer body
54
and block
90
have a number of outer grooves
112
which typically retain O-rings (not shown) that seal the injector
10
against the engine block. Additionally, block
62
and outer shelf
54
may be sealed to block
90
by O-ring
114
.
Block
60
has a passage
116
that is in fluid communication with the fuel port
64
. The passage
116
allows any fuel that leaks from the pressure chamber
66
between the block
62
and piston
84
to be drained back into the fuel port
64
. The passage
116
prevents fuel from leaking into the first intensifier chamber
88
.
The flow of working fluid (preferably engine lubricating oil) into the intensifier chambers
88
and
102
can be controlled by a four-way solenoid control valve
118
. The control valve
118
has a spool
120
that moves within a valve housing
122
. The valve housing
122
has openings connected to the passages
104
,
106
and
108
and a drain port
124
. The spool
120
has an inner chamber
126
and a pair of spool ports that can be coupled to the drain ports
124
. The spool
120
also has an outer groove
132
. The ends of the spool
120
have openings
134
which provide fluid communication between the inner chamber
126
and the valve chamber
134
of the housing
122
. The openings
134
maintain the hydrostatic balance of the spool
120
.
The valve spool
120
is moved between the first position shown in prior art
FIG. 1 and a
second opposed position, by a first solenoid
138
and a second solenoid
140
. The solenoids
138
and
140
are typically coupled to an external controller (not shown) which controls the operation of the injector. When the first solenoid
138
is energized, the spool
120
is pulled to the first position, wherein the first groove
132
allows the working fluid to flow from the supply working passage
108
into the first intensifier chamber
88
, and the fluid flows from the second intensifier chamber
102
into the inner chamber
126
and out the drain port
124
. When the second solenoid
140
is energized the spool
120
is pulled to the second position, wherein the first groove
132
provides fluid communication between the supply working passage
108
and the second intensifier chamber
102
, and between the first intensifier chamber
88
and the drain part
124
.
The groove
132
and passages
128
are preferably constructed so that the initial port is closed before the final port is opened. For example, when the spool
120
moves from the first position to the second position, the portion of the spool adjacent to the groove
132
initially blocks the first passage
104
before the passage
128
provides fluid communication between the first passage
104
and the drain port
124
. Delaying the exposure of the ports reduces the pressure surges in the system and provides an injector which has predictable firing points on the fuel injection curve.
The spool
120
typically engages a pair of bearing surfaces
142
in the valve housing
122
. Both the spool
120
and the housing
122
are preferably constructed from a magnetic material such as a hardened 52100 or 440c steel, so that the hystersis of the material will maintain the spool
120
in either the first or second position. The hystersis allows the solenoids
138
,
140
to be de-energized after the spool
120
is pulled into position. In this respect the control valve
118
operates in a digital manner, wherein the spool
120
is moved by a defined power pulse that is provided to the appropriate solenoid
138
,
140
. Operating the valve
118
in a digital manner reduces the heat generated by the coils and increases the reliability and life of the injector
50
.
In operation, the first solenoid
138
is energized and pulls the spool
120
to the first position, so that the working fluid flows from the supply port
110
into the first intensifier chamber
88
and from the second intensifier chamber
102
into the drain port
124
. The flow of working fluid into the intensifier chamber
88
moves the piston
84
and increases the volume of chamber
66
. The increase in the chamber
6

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