Valves and valve actuation – Electrically actuated valve – Including solenoid
Reexamination Certificate
1999-07-22
2002-04-02
Yuen, Henry C. (Department: 3747)
Valves and valve actuation
Electrically actuated valve
Including solenoid
C123S446000
Reexamination Certificate
active
06364282
ABSTRACT:
TECHNICAL FIELD
The present invention relates generally to fuel injection, and more particularly to hydraulically actuated fuel injectors with direct control check valve members, and fuel injection systems and methods using same.
BACKGROUND
Known hydraulically actuated fuel injection systems and/or components are shown, for example, in U.S. Pat. No. 5,121,730 issued to Ausman et al. on Jun. 16, 1992; U.S. Pat. No. 5,271,371 issued to Meints et al. on Dec. 21, 1993; and U.S. Pat. No. 5,297,523 issued to Hafner et al. on Mar. 29, 1994. In these hydraulically actuated fuel injectors, a spring biased check valve member opens to commence fuel injection when pressure is raised by an intensifier piston/plunger assembly to a valve opening pressure. The intensifier piston is acted upon by a relatively high pressure actuation fluid, such as engine lubricating oil, when a solenoid driven actuation fluid control valve opens the injector's high pressure inlet. Injection is ended by deactivating the solenoid to release pressure above the intensifier piston. This in turn causes a drop in fuel pressure causing the check valve member to close under the action of its return spring and end injection.
A hydraulically actuated fuel injector with a direct-control check valve is taught U.S. Pat. No. 5,738,075 issued to Chen et al. on Apr. 14, 1998. In a Fuel injector with a direct-control check valve, high pressure actuation fluid is also diverted to a check control chamber where it exerts pressure on a closing hydraulic surface of the check valve member. Since the direct-control check valve generally has a much faster response time than the actuation fluid control valve, the direct-control check valve can be used to more quickly close, or alternately and very quickly open and close, the check valve member, before the drop in fuel pressure occurs.
Operation of this type of hydraulically actuated fuel injector is illustrated in
FIGS. 2-4
, in which a single two-way actuator controls both the actuation fluid control and direct check control by exploiting a hysteresis (delayed) effect in an actuation fluid control valve versus the quick response of a check valve member in a check control valve. This fuel injector
101
utilizes a single two-way solenoid
130
to alternately open an intensifier control passage
109
to an actuation fluid inlet
106
or a low pressure actuation fluid drain
104
, and uses the same solenoid
130
to control the exposure of a check control chamber
118
to the actuation fluid inlet
106
or the actuation fluid drain
104
.
The injector
101
includes an injector body
105
having the actuation fluid inlet
106
connected to a branch rail passage, an actuation fluid drain
104
connected to the actuation fluid re-circulation line, and a fuel inlet
120
connected to a fuel supply passage. The injector
101
includes a hydraulic means for pressurizing fuel within the injector during each injection event and a check control valve that controls the opening and closing of a nozzle outlet
117
.
The hydraulic means for pressurizing fuel includes an actuation fluid control valve that includes the two-way solenoid
130
attached to a pin
135
. An intensifier spool valve member
140
responds to movement of the pin
135
and a ball valve member
136
to alternately open the intensifier control passage
109
to the actuation fluid inlet
106
or the low pressure drain
104
. The intensifier control passage
109
opens to a stepped piston bore
110
,
115
within which an intensifier piston
150
reciprocates between a return position (illustrated in
FIGS. 2 and 3
) and a forward position (not shown).
The injector body
105
also includes a plunger bore
111
, within which a plunger
153
reciprocates between a retracted position (illustrated in
FIGS. 2 and 4
) and an advanced position (not shown). Portions of the plunger bore
111
and the plunger
153
define a fuel pressurization chamber
112
, within which fuel is pressurized during each injection event. The plunger
153
and the intensifier piston
150
are returned to their retracted positions between injection events under the action of a compression spring
154
.
Thus, the hydraulic means for pressurizing fuel includes the fuel pressurization chamber
112
, plunger
153
, intensifier piston
150
, actuation fluid inlet
106
, intensifier control passage
109
, and the various components of the actuation fluid control valve, which includes the solenoid
130
, ball valve member
136
, pin
135
, and intensifier spool valve member
140
, etc.
Fuel enters the injector
101
at the fuel inlet
120
and travels past a ball check
121
, along a hidden fuel supply passage
124
, and into the fuel pressurization chamber
112
, when the plunger
153
is retracting. The ball check
121
prevents a reverse flow of fuel from the fuel pressurization chamber
112
into the fuel supply passage
124
during the plunger's downward stroke. Pressurized fuel travels from the fuel pressurization chamber
112
via a connection passage
113
to a nozzle chamber
114
. A check valve member
160
moves within the nozzle chamber
114
between an open position in which the nozzle outlet
117
is open and a closed position in which the nozzle outlet
117
is closed.
The check valve member
160
includes a lower check portion
161
and an intensifier portion
162
separated by spacers
164
and
166
, and is mechanically biased to its closed position by a compression spring
165
compressed between the spacer
164
and the intensifier portion
162
. Thus, when the check valve member
160
is closed and the check control chamber
118
is open to low pressure, the intensifier portion
162
is pushed to its upper stop.
The check valve member
160
includes opening hydraulic surfaces
163
exposed to fluid pressure within the nozzle chamber
114
, and a closing hydraulic surface
167
exposed to fluid pressure within the check control chamber
118
. The closing hydraulic surface
167
and the opening hydraulic surfaces
163
are sized and arranged so that the check valve member
160
is hydraulically biased toward its closed position when the check control chamber
118
is open to a source of high pressure fluid. Thus, there should be adequate pressure on the closing hydraulic surface
167
to keep the nozzle outlet
117
closed despite the presence of high pressure fuel in nozzle chamber
114
that may be otherwise above a valve opening pressure. The opening hydraulic surfaces
163
and closing hydraulic surface
167
are also preferably sized and arranged such that check valve member
160
is hydraulically biased toward its open position when the check control chamber
118
is connected to a low pressure passage and the fuel pressure within nozzle chamber
114
is greater than the valve opening pressure.
In the actuation fluid control valve area of the fuel to injector
101
, the two-way solenoid
130
is attached to a pin
135
. With the repulsive solenoid
130
de-energized, the pin
135
is pushed to a retracted position as the hydraulic force of the high pressure hydraulic fluid pushes the ball valve member
136
against an upper seat
172
. In this position, high pressure actuation fluid can flow past a lower seat
173
and into contact with an end hydraulic surface
141
of the intensifier spool valve member
140
. The force of the high pressure hydraulic fluid against the end hydraulic surface
141
balances the force of the high pressure hydraulic fluid against a bottom end of the spool valve member
140
so that a compression spring
145
can push the spool valve member
140
to its lower position.
When the spool valve member
140
is at its lower position the intensifier control passage
109
is blocked from receiving high pressure hydraulic fluid from a spool valve interior
147
past a high pressure access seat
171
, but instead is open to actuation fluid drain
104
past a drain access seat
170
.
When the solenoid
130
is energized, the pin
135
moves downward causing the ball valve member
136
to open the upper seat
172
a
Ausman Thomas G.
Tian Steven Y.
Bram Eric M.
Castro Arnold
Caterpillar Inc.
McNeil Michael B.
Yuen Henry C.
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