Information
-
Patent Grant
-
6684854
-
Patent Number
6,684,854
-
Date Filed
Friday, December 14, 200122 years ago
-
Date Issued
Tuesday, February 3, 200420 years ago
-
Inventors
-
Original Assignees
-
Examiners
Agents
-
CPC
-
US Classifications
Field of Search
US
- 123 446
- 123 506
- 123 467
- 123 458
- 123 9012
- 251 12909
- 251 1291
- 239 88
- 239 90
-
International Classifications
-
Abstract
An engine is provided comprising an engine housing defining at housing and has a different portion associated with each engine cylinder. Each different portion of the engine auxiliary system has a first electrical actuator coupled to a first valve and a second electrical actuator coupled to a second valve which are wired in series. For example, a fuel injection system is provided with a first electrical actuator operably coupled to a fuel pressurizer and a second electrical actuator operably coupled to a direct control needle valve. The electrical actuators are wired in series on an electrical circuit. A method of controlling a portion of the engine auxiliary system is also provided which consists of actuating a first electrical actuator with a relatively low current and actuating a second electrical actuator with a relatively high current.
Description
TECHNICAL FIELD
The present invention relates generally to auxiliary engine systems, and more particularly to such a system with two electrical actuators arranged in series on an electrical circuit.
BACKGROUND
Many electromechanical devices, including some fuel injectors, utilize two or more separate electrical actuators. This design offers numerous advantages over systems utilizing a single electrical actuator. Multiple actuator injection schemes enhance the potential control over valve actuation, allowing injection timing and duration, and fuel pressurization to be precisely controlled. In many cases, however, the additional hardware and circuitry necessary for a second actuator make its use cost-prohibitive. Moreover, system robustness and long term reliability may be compromised.
U.S. Pat. No. 6,113,014 to Coldren et al. discloses one method of incorporating a second electrical actuator into a fuel injector by wiring the solenoids in series. The use of a plurality of diodes in the circuit allows the solenoids to be selectively actuated, while avoiding the financial and functional problems associated with additional wiring and hardware. The Coldren design represents one successful way of addressing the problem, however, there is always room for improvement.
The present invention is directed to one or more of the problems associated with the prior art.
SUMMARY OF INVENTION
In one aspect, an engine is provided which comprises an engine housing defining at least one cylinder. At least one engine auxiliary system is attached to the engine housing and has a different portion associated with each of the at least one cylinder. Each different portion includes a first electrical actuator operably coupled to a first valve, and a second electrical actuator operably coupled to a second valve. An electrical circuit is associated with each of the at least one cylinder. In addition, the first electrical actuator and the second electrical actuator are arranged in series on the electrical circuit and are actuatable at a low current level and a high current level, respectively.
In another aspect, a fuel injection system is provided which comprises at least one body component, a first electrical actuator that is operably coupled to a fuel pressurizer, and a second electrical actuator that is operably coupled to a direct control needle valve. The first electrical actuator and the second electrical actuator are arranged in series on an electrical circuit and are actuatable at a low current level and a high current level, respectively. The first electrical actuator, the fuel pressurizer, the second electrical actuator, and the direct control needle valve are attached to the at least one body component.
In still another aspect, a method of controlling a portion of at least one engine auxiliary system associated with each engine cylinder is provided. The method includes the step of arranging a first electrical actuator and a second electrical actuator in series on an electrical circuit associated with each engine cylinder. The method also includes the step of actuating the first electrical actuator without actuating the second electrical actuator at least in part by establishing a relatively low current level in the electrical circuit. The method also includes the step of actuating the second electrical actuator at least in part by establishing a relatively high current level in the electrical circuit.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1
is a partial side diagrammatic view of an engine according to the preferred embodiment of the present invention;
FIG. 2
is a partial side diagrammatic view of an engine according to a second embodiment of the present invention;
FIG. 3
is a partial side diagrammatic view of an engine according to a third embodiment of the present invention; and
FIGS. 4
a
and
4
b
are graphs representing the current level and injection mass flow rate versus time, respectively, for an injection event according to the present invention.
DETAILED DESCRIPTION
Referring to
FIG. 1
, there is shown an engine
10
according to the preferred embodiment of the present invention. Engine
10
includes an engine housing
12
that defines at least one cylinder
14
, within which a reciprocating piston
16
is positioned. Engine
10
also includes a cam
60
which is operably coupled to a fuel pressurizer
50
that is preferably attached to a mechanically-actuated fuel injector
11
that has an injector body
19
. A direct control needle valve
30
is positioned within injector body
19
. A fuel supply
17
is provided and supplies low pressure fuel to injector
11
via a spill passage
18
. Engine
10
further provides an electronic control module
71
and an electrical circuit
70
that is associated with each of engine
10
's cylinders
14
. Engine
10
also includes at least one engine auxiliary system
20
, which in this case is a fuel injection system
15
, that is attached to housing
12
and has a different portion associated with each cylinder
14
. The term “auxiliary system” is intended to refer to fuel injection systems, gas exchange valves, engine brakes, EGR actuators, etc. that typically have individual portions associated with each engine cylinder.
Each portion of auxiliary system
20
, which in this example is fuel injection system
15
, includes a first electrical actuator
21
which is operably coupled to a first valve
24
that is a flow control valve, and a second electrical actuator
36
operably coupled to a second valve
37
, which is part of a direct control needle valve
30
. Electrical actuators
21
and
36
are preferably solenoid actuators, although it should be appreciated that some other device such as a piezoelectric actuator, a voice coil, etc. might be employed. First electrical actuator
21
and second electrical actuator
36
should be arranged in series on electrical circuit
70
, and are preferably actuatable at a low current level and a high current level, respectively. In the preferred embodiment, engine auxiliary system
20
includes a fuel injection system
15
, although it should be appreciated that additional engine systems might be incorporated with engine auxiliary system
20
. For instance, an engine brake, power steering, or some other system might be added to engine
10
or substituted for fuel injection system
15
without departing from the scope of the invention. In the preferred embodiment, fuel injection system
15
includes a plurality of mechanically-actuated fuel injectors
11
, each defining a fuel pressurization chamber
51
. The rotation of cam
60
drives a plunger
52
down to pressurize fuel in chamber
51
, while the action of a biasing spring
54
can return plunger
52
to its up position between pressurization strokes. Plunger
52
is operably coupled to cam
60
with a tappet
53
.
In the preferred embodiment, first valve
24
is a spill valve and is a portion of fuel pressurizer
50
. First valve
24
is preferably attached as a side car to injector body
19
and includes electrical actuator
21
which is comprised of a solenoid coil
22
and an armature
23
. Solenoid coil
22
is connected to electrical circuit
70
, and can thus be supplied with current when desired in a conventional manner as commanded by electronic control module
71
. Electrical actuator
21
is preferably actuatable at a relatively low current level. First valve
24
also includes a valve member
27
that is coupled to armature
23
by a biasing spring
26
. Armature
23
and valve member
27
are movable between an up and a down position by energizing or de-energizing electrical actuator
21
. A biasing spring
25
biases armature
23
and thus valve member
27
toward the down position when electrical actuator
21
is de-energized. It should be appreciated that the strength of biasing spring
25
should be such that the force it exerts on armature
23
and thus valve member
27
is sufficient to hold valve member
27
in its down position when the actuator is not energized. Biasing spring
26
should be such that it will assist movement of valve member
27
toward its down position relatively rapidly, when electrical actuator
21
is de-energized. In its down position, valve member
27
allows fluid communication between low pressure spill passage
18
and a fluid supply conduit
28
. Fluid supply conduit
28
is fluidly connected to pressurization chamber
51
which is defined in part by a valve body
19
and in part by plunger
52
.
Fluid supply conduit
28
is also in fluid communication with needle control valve
30
via a nozzle supply passage
29
. In the preferred embodiment, second valve
37
is a portion of needle control valve
30
. Supply passage
29
is connected to a nozzle chamber
32
that can be opened to cylinder
14
via a set of nozzle outlets
42
. Nozzle chamber
32
also connects to a needle control passage
31
. A needle control valve member
38
is movably positioned within injector body
19
and separates needle control passage
31
from a needle control chamber
45
. Second electrical actuator
36
includes a coil
33
and an armature
34
that is preferably coupled to needle control valve member
38
. Coil
33
is connected to electrical circuit
70
, and can be energized by command from electronic control module
71
by providing a relatively high level of current. A biasing spring
35
biases needle control valve member
38
toward a down position in which it provides fluid communication between needle control passage
31
and needle control chamber
45
. When valve member
38
is moved to an up position by activating actuator
36
, it blocks fluid communication between needle control chamber
45
and passage
31
. When in this position, needle control chamber
45
is fluidly connected to a low pressure vent passage
46
via a leakage clearance.
A needle valve member
39
is positioned within injector body
19
and is movable between an open (up) position in which nozzle outlets
42
are open, and a shut (down) position in which they are blocked. Because injector
11
has an injector tip
44
which preferably extends into cylinder
14
, when needle valve member
39
is in its up position, pressurized fuel in nozzle chamber
32
can spray out of nozzle outlets
42
into cylinder
14
. When needle valve member
39
is in its down position, fuel spray cannot occur. Needle valve member
39
has a closing hydraulic surface
41
which is exposed to fluid pressure in needle control chamber
45
, and an opening hydraulic surface
43
which is exposed to fluid pressure in nozzle chamber
32
. A biasing spring
40
is operably positioned to bias needle valve member
39
toward its shut/down position. It should be appreciated that the relative sizes of needle valve member
39
's hydraulic surfaces
41
and
43
, the flow area provided by needle control valve member
38
, and the strength of biasing spring
40
should be such that the hydraulic force on opening hydraulic surface
43
will move needle valve member
39
to its open position very shortly after electrical actuator
36
moves needle control valve member
38
to its up position. Similarly, the various components should be engineered such that needle valve member
39
can be moved to its shut position, halting fuel spray, relatively quickly when the termination of an injection event is desired, even in the presence of high pressure fuel acting on opening hydraulic surface
43
.
Referring to
FIG. 2
, there is shown an engine
110
representing a second embodiment of the present invention. This second embodiment is similar in many ways to the preferred embodiment illustrated in
FIG. 1
, yet has a number of significant differences. Rather than a mechanically-actuated fuel injector, engine
110
includes at least one hydraulically actuated fuel injector
116
with an intensifier piston
153
. Hydraulically actuated injector
116
provides a valve body
119
. Similar to engine
10
, engine
110
also includes an engine housing
12
, cylinder
14
, and piston
16
. An injector tip
144
preferably extends into cylinder
14
. A high pressure hydraulic fluid supply
111
is provided, and a low pressure fuel supply
17
. Engine
110
preferably uses engine lubricating oil as hydraulic fluid, however, it should be appreciated that transmission, brake, coolant, or some other suitable engine fluid might be used. A first valve
130
and a second valve
124
have been illustrated as being parts of separate fluid circuits, but could be modified to share a common hydraulic supply. A fuel pressurizer
150
is positioned within the injector body
119
and includes a piston
153
and plunger
152
. A direct control needle valve
138
is also housed within the injector body
119
. An electronic control module
71
is provided and is connected to an electrical circuit
170
. Engine
110
also includes a fuel injection system
115
, that is an engine auxiliary system, that is preferably attached to engine housing
12
.
Fuel injection system
115
provides a first electrical actuator
132
that is operably coupled to first valve
130
, which is preferably a flow control valve and is operable to control fluid flow to intensifier piston
153
. Fuel injection system
115
also includes a second electrical actuator
121
that is operably coupled to second valve
124
. Electrical actuators
121
and
132
are illustrated as solenoid actuators, however, it should be appreciated that another appropriate actuator such as a piezoelectric actuator might be substituted without departing from the scope of the present invention. In a manner similar to the preferred embodiment, first electrical actuator
132
is preferably actuatable at a relatively low current level, whereas second electrical actuator
121
is preferably actuatable at a relatively high current level.
High pressure supply
111
, which could be a common rail, supplies high pressure fluid to first valve
130
via a high pressure passage
112
. First electrical actuator
132
controls the state of flow control valve
130
and includes a solenoid coil
133
and an armature
134
. Armature
134
is connected to a valve member
138
and is movable between a left and a right position by energizing and de-energizing electrical actuator
132
. Valve member
138
has been illustrated as a spool valve member, however, it should be appreciated that some other suitable valve type such as a poppet or ball and pin might be substituted. A biasing spring biases poppet valve member
138
toward its right position. When valve member
138
is in its right position, high pressure passage
112
is blocked, but drain
117
in fluid communication with a pressure control passage
159
. In other words, spool valve member
138
provides fluid communication between pressure communication passage
156
and a low pressure drain
160
. When spool valve member
138
is moved toward its left position by energizing electrical actuator
132
, pressure control passage
159
is blocked to drain
160
, but opened to high pressure supply
112
.
As spool valve member
138
moves toward its left position, it opens fluid communication between passage
112
and pressure communication passage
159
, which fluidly connects to fuel pressurizer
150
. Fuel pressurizer
150
includes piston
153
and plunger
152
which are movable between an up position and a down position. A biasing spring
154
biases piston
153
and plunger
152
toward their up position. When fluid pressure is communicated to piston
152
via pressure communication passage
159
, piston
153
and plunger
152
are forced down, overcoming the force of biasing spring
154
to pressurize fuel in a fuel pressurization chamber
151
. After an injection event, piston
153
and plunger
152
can be moved back toward their retracted (up) position by the action of biasing spring
154
, drawing fuel into fuel pressurization chamber
151
via an inlet
149
from fuel supply
17
. As plunger
152
retracts, hydraulic fluid can be drained past spool
126
to a low pressure drain
117
via drain passage
160
.
Second electrical actuator
121
includes a coil
122
which is connected to electrical circuit
170
, and an armature
123
that is connected to a second valve
124
that includes a flow control valve member
127
which is movable between an up and a down position. A biasing spring
125
biases armature
123
and hence valve member
127
toward their down position, in which a nozzle supply line
129
can supply high pressure fluid from fuel pressurization chamber
151
. When actuator
121
is energized, and valve member
127
is moved toward its up position, fluid communication between nozzle supply line
129
and needle control chamber
145
, which is blocked, which becomes fluidly connected to a low pressure vent passage
114
via needle control passage
128
. Valve member
127
has been illustrated as a poppet valve, however, it should be appreciate that some other suitable valve type such as a spool or ball and pin might be substituted without departing from the scope of the present invention.
Needle control passage
128
is in fluid communication with a needle control chamber
145
. A closing hydraulic surface
141
of a needle valve member
139
is exposed to fluid pressure in needle control chamber
145
. Thus, either high pressure or low pressure may be provided to needle control chamber
145
by energizing or de-energizing actuator
121
to move valve member
127
between its respective positions. A biasing spring
140
biases needle valve member
139
toward its down position in which it closes a set of nozzle outlets
142
.
Fuel pressurized by the action of fuel pressurizer
150
is communicated to a nozzle chamber
137
via a nozzle supply passage
129
. Inside nozzle chamber
137
, the pressurized fuel can act on opening hydraulic surface
143
of needle valve member
139
to push needle valve member
139
up, opening nozzle outlets
142
and allowing fuel to spray into cylinder
14
. It should be appreciated that the sizing of needle valve member
139
's hydraulic surfaces
141
and
143
, and the strength of biasing spring
140
should be such that the increase in fuel pressure inside nozzle chamber
137
that results from the action of fuel pressurizer
150
is sufficient to lift needle valve member
139
away from nozzle outlets
142
when injection is desired. It is also desirable for needle valve member
139
to close nozzle outlets
142
relatively rapidly when termination of injection is desired.
Referring to
FIG. 3
, there is shown an engine
210
representing a third embodiment of the present invention. Engine
210
includes a housing
12
defining a cylinder
14
, and a piston
16
which is preferably positioned partially within cylinder
14
. Engine
210
also provides an engine auxiliary system
220
which is preferably a pump and line fuel injection system which includes a spill valve assembly
229
and a nozzle assembly
230
. A direct operated needle valve
247
is provided which is a portion of nozzle assembly
230
. Nozzle assembly
230
includes a tip
244
which is preferably positioned partially within cylinder
14
. Engine
210
further provides a fuel pressurizer
250
that includes a unit pump
246
that is separated from nozzle assembly
230
, and is preferably operably coupled to a cam
260
. An electronic control module
71
is provided and includes a current generator connected to an electrical circuit
270
.
Electrical circuit
270
connects electronic control module
71
to a first electrical actuator
221
and a second electrical actuator
232
in series. First electrical actuator
221
includes a coil
222
and an armature
223
and is operably coupled to a first valve
224
. Energizing and de-energizing electrical actuator
221
moves armature
223
between a down and an up position. A biasing spring
225
biases armature
223
toward its down position. First valve
224
, which is preferably a spill valve, includes a valve member
227
that is movable between an up and a down position, and functions in a manner similar to that described with respect to spill valve
21
illustrated in
FIG. 1. A
second biasing spring
226
assists in movement of valve member
227
toward its down position when the solenoid is de-energized. The force of biasing spring
225
preferably holds armature
223
and valve member
227
in their down positions, when electrical actuator
221
is de-energized. In this position, valve member
227
provides fluid communication between a spill passage
218
and an engine fuel tank
17
. When electrical actuator
221
is energized, and valve member
227
is moved to its up position, fluid communication between spill passage
218
and fuel tank
17
is blocked. Thus, fluid supplied to first valve
224
can flow to fuel tank
17
when electrical actuator
221
is de-energized, but does not when electrical actuator
222
is energized.
Spill passage
218
fluidly connects to a pump passage
248
and a fluid supply conduit
228
. Pump passage
248
fluidly connects to unit pump
246
and is supplied with pressurized fuel by unit pump
246
's pumping action. Fluid supply conduit
228
is connected to nozzle assembly
230
via an inlet
249
. A nozzle supply passage
251
defined by valve body
219
supplies fluid via inlet
249
to a nozzle chamber
236
. Nozzle chamber
236
in turn fluidly connects to a needle control passage
231
which can supply pressurized fluid to a needle control chamber
245
. Second electrical actuator
232
is positioned within valve body
219
and includes a coil
233
and an armature
234
, and is preferably actuatable at a relatively high current level. Armature
234
is connected to a needle control valve member
238
and is movable between an up and a down position, regulating the fluid pressure supplied to needle control chamber
245
in a manner similar to the
FIG. 1
embodiment. A biasing spring
240
is positioned to bias needle valve member
239
down to shut nozzle outlets
242
. Opening hydraulic surface
243
and a closing hydraulic surface
241
serve an analogous purpose to hydraulic surfaces
41
and
43
which were described with regard to the present invention's
FIG. 1
embodiment.
Industrial Applicability
Referring to
FIG. 1
, there is shown the preferred embodiment of the present invention with its various components in the positions they would occupy between injection events. Cam
60
is continuously rotating, driving plunger
52
down to pressurize fuel in pressurization chamber
51
. Return spring
54
pushes valve member
52
back toward its retracted position, drawing fuel into pressurization chamber
52
from fuel supply
17
between pressurization strokes. Electrical actuator
21
is de-energized, and valve member
27
allows fluid communication between fluid supply conduit
28
and fuel tank
17
. Pressurized fuel from pressurization chamber
51
can thus flow via flow control valve
24
to fuel tank
17
for re-circulation. Electrical actuator
36
is also de-energized, and needle control valve member
38
is in its down position where it provides fluid communication between needle control passage
31
and needle control chamber
45
. Fluid pressurized from the action of fuel pressurizer
50
is supplied via nozzle supply passage
29
and nozzle chamber
32
to needle control passage
31
. The force of biasing spring
40
and the hydraulic force on needle closing hydraulic surface
41
in chamber
45
combine to hold needle valve member
39
in its down position, closing nozzle outlets
42
.
Between injection events, no current is supplied to electrical circuit
70
. Referring now in addition to
FIGS. 4
a
and
4
b
, a sample split injection event is illustrated. When initiation of a fuel injection event is desired, a relatively low pull in current level (LP) is established in electrical circuit
70
with electronic control module
71
to actuate first electrical actuator
21
without actuating second electrical actuator
36
. When first electrical actuator
21
is energized, armature
23
is pulled toward coil
22
, overcoming the force of biasing spring
25
. As armature
23
moves up, fluid communication between fluid supply conduit
28
and fuel tank
17
becomes blocked. A relatively greater current level is necessary to move armature
23
to its up position than that necessary to hold armature
23
in its up position. Thus, once electrical actuator
21
has been energized for a time sufficient to move armature
23
and valve member
27
to the up position, the current level may be reduced to a low hold level (LH), significantly reducing energy expenditure. Because second electrical actuator
36
remains stationary, since it is not sufficiently energized to overcome the preload of spring
35
, the hydraulic pressure can increase to an injection pressure in fuel pressurization chamber
51
, nozzle chamber
32
, and needle control chamber
45
as well as passages
29
and
31
which connect the respective chambers. Consequently, the hydraulic force on needle closing hydraulic surface
41
and the force of biasing spring
40
remain sufficient to overcome the force on needle opening hydraulic surface
43
, and needle valve member
39
is held in its down position, blocking nozzle outlets
42
.
Just prior to the moment that injection is desired, the current in electrical circuit
70
is increased to a high pull-in level (HP) which is relatively higher than the pull-in level necessary to actuate first electrical actuator
21
, and sufficient to actuate electrical actuator
36
. When electrical actuator
36
is thus energized, armature
34
and needle control valve member
38
begin to move toward the up position in which fluid communication between needle control passage
31
and needle control chamber
45
is blocked. In a manner similar to first electrical actuator
21
, the high hold current (HH) for electrical actuator
36
is less than the pull in current, and the current level may be reduced once armature
34
and valve member
38
reach their upper position. In the preferred embodiment, the high pressure fuel in needle control chamber
45
bleeds through a controlled leak clearance with valve body
19
, allowing pressure to drop in needle control chamber
45
when fluid communication with needle control passage
31
is blocked. The hydraulic pressure acting on opening hydraulic surface
43
becomes sufficient to lift needle valve member
39
to open nozzle outlets
42
, allowing fuel from nozzle chamber
32
to spray into cylinder
14
.
Just prior to the instant that termination of injection is desired, input current to electrical circuit
70
should be shut off. As the electrical current and corresponding solenoid forces decay, second electrical actuator
36
becomes sufficiently de-energized to allow armature
34
and valve member
38
to begin to move back toward their down position under the force of biasing spring
35
. Fluid communication between needle control passage
31
and needle control chamber
45
is reestablished, and the force of biasing spring
40
and the hydraulic force again acting on closing hydraulic surface
41
can force needle valve member
39
down to close nozzle outlets
42
, ending fuel injection. Because the current necessary to actuate second electrical actuator
36
is preferably greater than the current necessary to actuate first electrical actuator
21
, second electrical actuator
36
should de-activate before first electrical actuator
21
. When the current in electrical circuit
70
and corresponding solenoid force associated with first electrical actuator
21
fall sufficiently, the force of biasing springs
25
and
26
move armature
23
and valve member
27
down, to reestablish fluid communication between fluid supply conduit
28
and fuel tank
17
via spill passage
18
. As a result, the remaining fluid pressure in the system can dissipate, allowing the injection cycle to start over again.
Referring to
FIG. 2
, the various components of this second embodiment of the present invention are shown in the positions they would occupy between injection events. High pressure fluid is continuously supplied to engine
110
and its engine auxiliary system
115
from high pressure supply
111
. As in the preferred embodiment, no current is supplied to electrical circuit
170
between injection events. In this state, first electrical actuator
132
is de-energized, and armature
134
and valve member
138
are held in their right position by biasing spring
135
. Valve member
138
allows fluid communication between drain passage
160
and pressure control passage
159
. Because pressure communication passage
156
is blocked from fluid communication with high pressure passage
112
, low pressure is supplied to fuel pressurizer
150
and the force of biasing spring
154
can hold plunger
152
in its retracted position. With plunger
152
in its retracted position, pressurization chamber
151
should be at a relatively low pressure. Nozzle supply passage
129
nozzle chamber
137
, and needle control chamber
145
should likewise be at a relatively low pressure.
Between injection events, with the current supply at zero, second electrical actuator
121
is also de-energized. Armature
123
and valve member
127
are in their down position, allowing fluid communication between nozzle supply line
129
and needle control passage
128
. Fluid supply conduit
128
thus provides needle control chamber
145
with fuel fluid. The hydraulic force acting on needle closing hydraulic surface
141
and the force of biasing spring
140
hold needle valve member
139
down, closing nozzle outlets
142
.
When the beginning of an injection cycle is desired, current is supplied to electrical circuit
170
which is sufficient to actuate first electrical actuator
132
, but possibly not sufficient to actuate second electrical actuator
121
. In a manner similar to that described with respect to the preferred embodiment, the current may be reduced from its pull-in level to a hold-in level when appropriate. When the current is supplied to coil
133
, armature
134
and valve member
138
are pulled toward their left position, opening fluid communication between pressure control passage
159
and high pressure passage
112
. High pressure fluid supplied to pressure communication passage
159
acts on piston
153
, driving plunger
152
down to pressurize fuel in pressurization chamber
151
. Because needle valve member
139
is held down to close nozzle outlets
142
, pressure in nozzle chamber
137
can build to an injection pressure.
Just prior to the moment at which initiation of fuel injection is desired, the current level in electrical circuit
170
is raised to a relatively high level. This can be down simultaneous with initial current or at some time thereafter to produce a variety of front end rate shaping effects. In a fashion similar to the preferred embodiment, current may be reduced from a pull-in level to a hold-in level. Electrical current to coil
122
causes armature
123
and valve member
127
to move toward their up position, opening fluid communication between fluid supply conduit
128
and vent passage
114
. This causes a relatively sudden drop in pressure in fluid supply conduit
128
and, consequently, in needle control chamber
145
. This decrease in pressure results in a decrease in the force acting on closing hydraulic surface
141
. The force on opening hydraulic surfaces
143
can overcome the force of biasing spring
140
to move needle valve member
139
up, opening nozzle outlets
142
and allowing fuel to spray into cylinder
14
.
When termination of injection is desired, the current to electrical circuit
170
should be shut off. The decay of the current and resulting decay of solenoid forces first causes second electrical actuator
121
to de-activate, followed by the de-activation of first electrical actuator
132
. As armature
123
and valve member
127
return to their down positions under the force of biasing spring
125
, fluid communication between vent passage
114
and fluid supply conduit
128
is shut off. At the same time, fluid communication is reestablished between fluid supply conduit
128
and nozzle supply line
129
, resulting in a significant increase in fluid pressure to needle control chamber
145
. As the pressure in needle control chamber
145
increases, the hydraulic force on closing hydraulic surface
141
and the force of biasing spring
140
can overcome the force on opening hydraulic surfaces
143
to push needle valve member
139
down, closing nozzle outlets
142
and ending injection. When current in electrical circuit
170
decays sufficiently, first electrical actuator
132
becomes sufficiently de-energized and armature
134
and valve member
138
begin to move toward their right positions. Valve member
138
is moved by the force of biasing spring
135
to its right position, blocking fluid communication between high pressure passage
112
and pressure communication passage
159
. The force of return spring
154
can then move plunger
152
and piston
153
back toward their up position, displacing the used hydraulic fluid to drain
117
via passage
160
. As plunger
152
moves up, fuel is drawn into pressurization chamber
151
via inlet
149
from fuel supply
17
in preparation for another injection cycle.
Referring to
FIG. 3
, the third embodiment of the present invention is shown with its various components in the positions they would occupy between injection events. Cam
260
is preferably rotating at half engine speed in order to be in its pumping stroke at about the time of an injection event at that cylinder. Pump line
248
supplies pressurized fuel to fuel supply conduit
228
and spill passage
218
. No current is supplied to the system, and thus both first electrical actuator
221
and second electrical actuator
232
are de-energized. Valve member
227
is in its down position, and thus allows displaced fuel from unit pump
246
to drain from spill passage
218
back to the engine fuel tank
17
for re-circulation. With second electrical actuator
232
de-energized, needle control valve member
238
allows fluid communication between needle biasing passage
231
and needle control chamber
245
. Thus, the force of biasing spring
240
and the hydraulic force on closing hydraulic surface
241
can hold needle valve member
239
in its down position, closing nozzle outlets
242
.
Just prior to the moment at which initiation of an injection event is desired, a relatively low pull in (LP) level of current is supplied to electrical circuit
270
which is sufficient to actuate first electrical actuator
221
. Valve member
227
is pulled toward its up position, blocking fluid communication between spill passage
218
and fuel tank
17
. The continuous action of unit pump
246
causes the fluid pressure in the system to rise significantly. When the system has reached the desired injection pressure, the current in electrical circuit
270
may be raised to a level sufficient to actuate second electrical actuator
232
. Like the previously discussed embodiments, current may be reduced to a hold-in level from a pull-in level to improve engine energy efficiency. But more importantly, reducing current prevents overheating of electrical components and reduces the size of the boost voltage power supply. When second electrical actuator
232
is actuated, valve member
238
is pulled toward its up position, blocking fluid communication between needle biasing passage
231
and needle control chamber
245
. Like the preferred embodiment, the present embodiment preferably employs a controlled leakage from needle control chamber
245
, allowing the pressure to bleed off, and the force on opening hydraulic surfaces
243
to push needle valve member
239
up to open nozzle outlets
242
.
Just prior to the desired termination of an injection event, current to electrical circuit
270
should be shut off. As the current level drops, second electrical actuator
232
de-energizes, allowing armature
234
and valve member
238
to move back toward their down position, once again allowing pressurized fluid from needle biasing passage
231
and the force of biasing spring
240
to push needle valve member
239
down, closing nozzle outlets
242
and ending fuel injection. As the current decays further, first electrical actuator
221
is de-energized sufficiently to allow armature
223
and valve member
227
to return to their down position under the force of biasing springs
225
and
226
. As valve member
227
reopens fluid communication between spill passage
218
and fuel tank
17
, fluid pressurized by unit pump
246
can once more drain out of the system
220
. The pressure in fuel supply conduit
228
drops significantly, with a concomitant decrease in the fluid pressure in nozzle supply passage
251
and nozzle chamber
236
.
Referring to
FIGS. 4
a
and
4
b
, there are shown a set of graphs representing the current level, I (HP=high-pull; HH=high-hold; LP=low-pull; LH=low-hold) versus time “T” during an injection event, and the mass flow rate “Q” over time “T” during an example split injection for all embodiments of the present invention. The injection event illustrated in
FIGS. 4
a
and
4
b
represents a relatively small pilot injection followed by a relatively large main injection, or split injection, although it should be appreciated that a variety of injection rate shapes and injection types for varying operating conditions might be possible with the present invention. For instance, a ramp or single square injection might be desirable rather than the split injection shown. As illustrated in
FIG. 4
a
, an injection event is initiated by applying a first pull-in current at a level LP to the electrical circuit to move the armature of the first electrical actuator toward the solenoid stator. The current supplied to the electrical circuit is then reduced to a first hold-in current level LH, requiring significantly less energy consumption. This action allows fuel pressure in the system to begin rising to injection pressure levels. The magnitudes of the LP and LH current levels are preferably selected such that the magnetic forces developed thereby on the armature of the first electrical actuator are sufficient to overcome the biasing force of the biasing spring(s) acting on the armature. However, the magnitudes of the LP and LH currents are preferably such that the magnetic forces developed on the armature of the second electrical actuator at the LP and LH current levels are insufficient to overcome the force of its biasing spring.
When it is desirable to open the injector's nozzle outlets for fuel injection, for example in the pilot injection shown in
FIGS. 4
a
and
4
b
, the current is increased to a relatively high pull-in level HP to move the second electrical actuator's armature to its solenoid stator. The current to the electrical circuit may then be reduced to a relatively lower level HH to allow completion of the desired amount of pilot injection. After the pilot injection, current is reduced once again to the LH level, allowing the armature of the second electrical actuator to move toward its de-energized position, terminating the pilot injection. In the injection scheme illustrated in
FIGS. 4
a
and
4
b
, the current supplied to the electrical circuit should be maintained at a level that is sufficient for the first electrical actuator to remain energized, its armature continuing to be held against the solenoid stator, allowing pressure in the system to be sustained at the desired injection pressure. When main injection is desired, the current is once again increased to a level HP sufficient to actuate the second electrical actuator, then reduced to the relatively lower level HH. When termination of main injection is desired, the current in the electrical circuit is preferably shut off entirely. However, it may be desirable to have a LH current at the end of injection in order to assure that the needle valve closes before the spill valve closes to prevent end of injection variability. Finally, instead of different pull-in currents, one pull in current with different current duration could possibly be used.
By combining the operating benefits of a dual solenoid injector with the disclosed single circuit design, the present invention allows precise control over injection timing and fuel pressurization, while reducing excess hardware, such as wiring, and enhancing system robustness. The multi-level current scheme for selectively actuating the two solenoids might find application in other areas, or in improved versions of the present invention. For instance, actuators used in other engine systems might be wired in series with the actuators from the present invention. In this manner, numerous engine systems such as an engine brake and a fuel injector, might be operated on a single circuit by varying and possibly reversing the current levels, resulting in a substantial improvement in engine efficiency and overall system robustness, as well as decreased production and maintenance costs.
Thus, those skilled in the art will appreciate that other aspects, objects and advantages of this invention can be obtained from a study of the drawings, the disclosure and the appended claims
Claims
- 1. An engine comprising:an engine housing defining at least one cylinder; at least one engine auxiliary system attached to said engine housing and having a different portion associated with each of said at least one cylinder, and each said different portion including a first electrical actuator operably coupled to a first valve and a second electrical actuator operably coupled to a second valve; an electrical circuit associated with each of said at least one cylinder; and said first electrical actuator and said second electrical actuator being arranged in series on said electrical circuit and being actuatable at a low current level and a high current level, respectively, and said first and second electrical actuators being oriented on different centerlines.
- 2. The engine of claim 1 wherein said at least one auxiliary system includes a fuel injection system;said first valve being a portion of a fuel pressurizer; and said second valve being a portion of a direct operated needle valve.
- 3. The engine of claim 2 wherein said second electrical actuators attached to a needle control valve member.
- 4. The engine of claim 3 wherein said first valve is a flow control valve.
- 5. The engine of claim 4 wherein said fuel injection system includes at least one hydraulically actuated fuel injector with an intensifier piston; andsaid flow control valve being operable to control fluid flow to said intensifier piston.
- 6. The engine of claim 4 wherein said fuel injection system includes a plurality of mechanically actuated fuel injectors, each defining a fuel pressurization chamber; andsaid flow control valve being operable to open and close said fuel pressurization chamber to a spill passage.
- 7. The engine of claim 3 wherein said fuel pressurizer includes a unit pump;said direct operated needle valve is a portion of a nozzle assembly separated from said unit pump; and said unit pump being fluidly connected to said nozzle assembly by a fluid supply conduit.
- 8. The engine of claim 7 wherein said supply conduit is a fuel supply conduit.
- 9. A fuel injection system comprising:at least one body component; a first electrical actuator being operably coupled to a fuel pressurizer; a second electrical actuator being operably coupled to a direct control needle valve; said first electrical actuator and said second electrical actuator being arranged in series on an electrical circuit and being actuatable at a low current level and a high current level, respectively; and said first, electrical actuator, said fuel pressurizer, said second electrical actuator, and a nozzle needle valve being attached to said at least one body component., and said first and second electrical actuators being oriented on different centerlines.
- 10. The fuel injection system of claim 9 wherein said second electrical actuator is attached to a needle control valve member.
- 11. The fuel injection system of claim 10 wherein said first electrical actuator is operably coupled to a flow control valve.
- 12. The fuel injection system of claim 11 wherein said first electrical actuator, said fuel pressurizer, said second electrical actuator, and a nozzle needle valve are attached to a unit injector body.
- 13. The fuel injection system of claim 12 including an intensifier piston positioned in said unit injector body; andsaid flow control valve being operable to control fluid flow to said intensifier piston.
- 14. The fuel injection system of claim 12 including a cam actuated plunger attached to said unit injector body, and defining a portion of a fuel pressurization chamber; andsaid flow control valve being operable to open and close said fuel pressurization chamber to a spill passage.
- 15. The fuel injection system of claim 12 wherein said fuel pressurizer includes a unit pump;said direct control needle valve is a portion of a nozzle assembly separated from said unit pump; and said unit pump being fluidly connected to said nozzle assembly by a fluid supply conduit.
- 16. The fuel injection system of claim 15 wherein said supply conduit is a fuel supply conduit.
- 17. A method of controlling a portion of at least one engine auxiliary system associated with each engine cylinder, comprising the steps of:arranging a first electrical actuator and a second electrical actuator on different centerlines but in series on an electrical circuit associated with each engine cylinder; actuating the first electrical actuator without actuating the second electrical actuator at least in part by establishing a relatively low current level in the electrical circuit; and actuating the second electrical actuator at least in part by establishing a relatively high current level in the electrical circuit.
- 18. The method of claim 17 including a step of resetting the first electrical actuator and the second electrical actuator at least in part by reducing a current level in the electrical circuit below the relatively low current level.
- 19. The method of claim 18 wherein said step of actuating the first electrical actuator includes a step of pressurizing fuel for a fuel injection event.
- 20. The method of claim 19 wherein said step of actuating the second electrical actuator includes a step of opening a nozzle to inject fuel into an engine cylinder.
US Referenced Citations (46)
Foreign Referenced Citations (1)
Number |
Date |
Country |
2339077 |
Jan 2000 |
GB |