Note: Descriptions are shown in the official language in which they were submitted.
~eScriptiQn
Rotary-Fuel Injection Apparatus
With Pilot Injection
Technical Field
This invention relates generally to internal
; combustion engines and more particularly ~o those
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having electrically controlled fuel injection.
Background Art
- Electrical control of fuel injection is
versatile and thus advantageous. In general, it allows
accomplishment of several important objectives such as
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excellent control of exhaust emissions; improved engine
response; programming of desired torque characteristics
of the engine; programming of desired speed regulations;
lS provision for rapid shutdown of engines; and improved
fuel economy.
A rotary controlled fuel injection apparatus
~ has been provided with dual rotary controlled valves
-~ for controlling the amount of fuel injected into an
engine which reduced inertial forces associated with
prior art valves used for fuel injec~tion.
The advent of dual rotary controlled fuel
injection provides a foundation fpr a new era of
innovation in fuel injection apparatus. For example,
-~ 25 pilot injection is ordinarily accomplished in one of
-` two ways. First, if one injector or nozzle is used,
then two fuel pumps deliver fuel to one fuel line via
check valves. One of the two pumps delivers a short
burst of high pressure fuel, the duration of which is
' 30 determined by any of the conventional ways, such as by
use of a scroll. Then, after a brief pause, the other
of the two pumps delivers a main charge of fuel also
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through a check valve. A limitation of pilot injection
done this way is that it is expensive because it requires
the use of two separate fuel pumps. Some economy is
realized, however, because only one fuel nozzle is used.
In situations where pilot injection is done
through one nozzle and the main charge is delivered
through another nozzle, two fully independent systems are
used; each one having a fuel pump and nozzle. Thus,
expense and bulk are limitations of pilot injection
accomplished this way.
Another limi~ation of previously known pilot
injection systems is that they are not readily adaptable
to independently controlling the timing and duration of
both the pilot and the main injection.
As a result, pilot injection in general, is not a
widely used way of injecting fuel. Originally introduced
to reduce ignition lag, it was found to be complex when
- compared to the benefits received since it required added
equipmentr cost, bulk, weight and the resultant
maintenance.
The foregoing illustrates limitations of the
known prior art. Thus, it is apparent that it would be
advantageous to provide an alternative to the known prior
art.
- Disclosure of Invention
-
In one aspect of the present invention, there is
provided a fuel injection apparatus comprising a housing,
the housing having a plunger bore; a plunger reciprocably
mounted in the plunger bore; means for conducting fuel to
and from the plunger bore; means for starting and stopping
pilot injection and main injection of the fuel, the means
for starting and stopping including a plurality of valves
connected for continuous rotation at a constant rate, the
valves being fluidly interconnected and being fluidly
connected to the plunger bore.
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The foregoing and other aspects will become
apparent from the following detailed description of the
invention when considered in conjunction with the
accompanying drawings. It is to be expressly under-
stood, however, that the drawings are not intended as
a definition of the invention but are for the purpose
of illustration only.
Brief Description of the Drawings
Figure 1 is a diagrammatic view illustrating a
fuel system including a unit fuel injection apparatus;
Figures 2A and 2B on sheet three of the drawings
are isometric views illustrating rotary valves having
blocking shoulders;
Figures 3A, 3B and 3C are partial diagrammatic
views illustrating sequential steps of rotary controlled
fuel injection;
Figure 4 on sheet three of the drawings is a
diagrammatic view illustrating an adjustment control for
use in the fuel system; and
Figure 5 on sheet two of the drawings is a
fragmentary view illustrating another embodiment
utilizing three valves.
Best Mode for Carrying Out the Invention
In Figure 1, a unit fuel injection apparatus
is designated 10 and includes a unit fuel injector pump
12 operatively connected in a system including a known
fuel supply tank or reservoir 14 from which fuel is
transferred to the fuel injector pump 12 by a known
fuel transfer pump 16, preferably through a filter 18.
The fuel is supplied to a housing 24 through a conduit
17. Fuel enters housing 24 at an inlet port 56 of fuel
conduit 20. Fuel exits from a fuel conduit 22 in
housing 24 at an outlet port 62 and is conducted back
to tank 14 through a conduit 19.
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Unit fuel lnjection pump 12 includes housing
24 having a tappet 28 resiliently biased by spring 30
and driven by a lobe 32 on a camshaEt 34 as is well
~nown. As a result, a plunger 36 is a means for
reciprocating in a first bore 38 within housing 24.
Fuel, delivered to first bore 3~, is injected into an
engine cylinder (not shown) past a one-way check valve
49, through an injection passage 40 and injection ports
42 in a tip assembly 44. This well known arrangement
functions due to differential areas on a fuel injection
valve 46 biased by a spring 48 in a tip assembly 44.
The fuel is expelled through ports 42 due to
its substantial pressurization periodically occurring
in a cavity 100 of first bore 3& as plunger 36 con-
tinuously reciprocates. Controlling the quantity andtiming of the injection of fuel through ports 42 is the
subject of much technology due to present trends in
enhancing fuel economy and reducing fuel emissions.
Such technology is complicated because the control of
quantity and timing must be coordinated with other
~; engine functions and conditions. Since the lobe 32 and
plunger 36 have a fixed cyclical relationship for
pressurizing the fuel in first bore 38, variations in
controlling quantity and timing of injection usually
involve electrical and/or mechanical control of the
admittance of fuel to first bore 38. For example, this
has been accomplished by a scroll (helix) on the
plunger which is rotated with a rack. As illustrated,
plunger 36 reciprocates between a dotted line position
"A" and a solid line position "B".
Fuel conduit 20 extends into housing 24 from
port 56 and terminates at bore 38 adjacent an end 52 of
plunger 36. Thus, conduit 20 functions as a means
for conducting fuel to cavity 100 of plunger bore 38.
Fuel conduit 22 extends from cavity 100 of plunger bore
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38, through housing 24 -to port 62. Thus, conduit 22
functions as a means for conducting fuel from plunger
bore 38.
Conduit 20 is in fluid communication with
cavity 100 when plunger 36 is in position "A" but not
in position "s". Conduit 22 is in fluid communication
with cavity 100 when plunger 36 is in any position
between "A" and "B". Conduit 22 separates or diverges
to form a first branch or conduit portion 22a between
10 cavity 100 and outlet port 62 and a second separate
branch or conduit portion 22b between cavity 100 and
outlet port 62. Conduits 22a, 22b converge adjacent
outlet port 62.
A first enlarged bore 70 is transversely
disposed in conduit 22a. Bore 70 is of a construction
sufficient for accommodating a first valve 72 which
rotates to function as a means for starting and stopping
pilot injection and for starting main injection. Valve
~ 72 is mounted in housing 24 for rotation in bore 70 in
- 20 a lapped fit. Valve 72 has an enlarged outer cylindrical
surface 76 for lubricated rotating engagement with an
inner cylindrical surface 77 of bore 70 A reduced
diameter portion 78 of valve 72 is adjacent a high
pressure inlet 81 and a relatively low pressure outlet
25 83 at an intersection of conduit 22a and bore 70. A
raised arcuate blocking shoulder 82 is formed on
reduced diameter portion 78 of valve 72. An outer
` arcuate surface 84 of shoulder 82 rotatably engages
inner surface 77 of bore 70 in a manner sufficient for
blocking inlet 81, thus limiting passage of fuel
through conduit 22a to port 62. Shoulder 82 and thus
arcuate surface 84, have a first arcuate length Ll
(Figs. 2A, 2B, 3A, 3B, 3C) for permitting shoulder 82
to block inlet 81 for a certain brief duration for
; 35 starting and stopping pilot injection. Blocking
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shoulder 82 is timed to block inlet 81 when plunger 36
is blocking conduit 20 and is moving toward position
"B" when injection can occur since, as it is well
- known, injection can occur only when fuel is being
compressed in cavity 100.
First valve 72 has a second arcuate blocking
shoulder 82a formed on reduced diameter portion 78 of
valve 72. An outer arcuate surface 84a of shoulder 82a
rotatably engages inner surface 77 of-bore 70 in a
manner sufficient for blocking outlet 83 thus limiting
passage of fuel through conduit 22a to port 62.
Shoulder 82a and thus arcuate surface 84a, have a
second arcuate length L2 (Figs. 2A, 2B, 3A, B, C)
greater than length Ll for permitting shoulder 82a to
block outlet 83 for a certain duration for starting
main injection. Shoulder 82a is located on valve 72 in
such a manner to be timed for blocking outlet 83
shortly after pilot injection ends. This blockage also
occurs when plunger 36 is blocking conduit 20 and is
moving toward position "B" when injection can occur.
- A second enlarged bore 90 (Fig. 1) is trans-
versely disposed in conduit 22b. Bore 90 is of a
construction sufficient for accommodating a second
valve 92 which rotates to function as a means for
stopping main injection. Valve 92 is mounted in
housing 24 for rotation in bore 90 in a lapped fit.
Valve 92 has an enlarged outer cylindrical surface 96
for lubricated rotating engagement with inner cylin-
;~ drical surface 97 of bore 90. A reduced diameter
~;~ 30 portion 98 of valve 92 is adjacent a high pressure
~ inlet 101 and a relatively low pressure outlet 103 at
`~ an intersection of conduit 22b and bore 90. A raised
arcuate blocking shoulder 102 is formed on reduced
diameter portion 98 of valve 92. Outer arcuate surface
104 of shoulder 102 rotatably engages inner surface 96
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of ~ore 90 in a manner sufficient for blocking inlet
101, thus limiting passage of fuel throùgh condui-t 22b
to port 62. Shoulder 102, and thus surface 10~, have a
second arcuate length L3 (Figs. 2A/ 2~, 3A, 3B, 3C)
greater than first arcuate length Ll and second arcuate
length L2, thus permitting shoulder 102 to block inlet
101 for a greater duration than the duration which
shoulders 82 and 82a blocks inlets 81 and 83. Shoulder
102 is timed to block inlet 101 ~hen plunger 36 is
blocking conduit 20 and is moving toward position "B"
when injection can occur. Also, shoulder 102 blocks
inlet 101 prior to and during the entire time when
shoulder 82 blocks inlet 31 to permit shoulder 82 to
start and stop pilot injection. Further! shoulder 102
15 is still blocking inlet 101 when shoulder 82a begins to
block outlet 83 for starting main injection. However,
when shoulder 82a is still blocking outlet 83, shoulder
102 clears or rotates past inlet 101 thus stopping main
injection.
In Figure 1 it can be seen that conduit 22a
bypasses valve 72, but conduits 22a, 22b fluidly
interconnect first valve 72 and second valve 92 due to
their common connection to conduit 22 and port 62.
; Also, by virtue of interconnected conduits 22a, 22b,
plunger bore 38 is fluidly connected to first valve 72
and second valve 92 permitting conduit 22 to conduct
fuel from cavity 100 and simultaneously provide the
; fuel to first valve 72 and second valve 92.
Figures 3A, 3B, 3C graphically illustrate the
relative positions of valves 72, 92 rotating in bores
70, 90, respectively, for starting and stopping pilot
and main injection. In Figure 3A, with plunger 36
blocking conduit 20, shoulder 102 of valve 92 blocks
inlet 101 but since shoulder 82 of valve 72 is not
blocking intersection 81, no injection occurs and fuel
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bypasses valve 72 from cavity 100 via conduit 2~a and
returns to tank 14. In Figure 3B, however, shoulders
82,102 si~ultaneously block their respective inlets
81,101 thus causing fuel to be pilot injected. Pilot
injection stops after shoulder 82 rotates past inlet
81. Then, as illustrated in solid line in Figure 3C,
shoulder 82a of valve 72 and shoulder 102 of valve 92
-simultaneously block inlets 83,101, respectively, for
starting main injec-tion. Thereafter, although shoulder
82a (dotted line~ still blocks inlet ~3l main injection
stops since shoulder 102 (also dotted line) of valve 92
is no longer blocking inlet 101. Thus, injection stops
and fuel bypasses valve 92 from cavity 100 via conduit
22b and returns to reservoir 14. It can be seen how
shoulder 82 controls pilot injection starting and
stopping and shoulder 82a controls main injection
starting whereas shoulder 102 controls main injection
stopping. Continuous rotation of valves 72,92, at the
same constant rotational speed causes intermittent
-20 blockage of conduit 22. Phasing (discussed below) the
relative positions of shoulders 82,102 for sequential
and simultaneous blockage of conduit 22 results in
~`control of timing and duration of fuel injection.
Means are provided for continuously rotating
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-~25 valve 72 and an additional identical means is required
to continuously rotate valve 92. However, only one of
the identical means 119 is shown in Figure 4 and
described below. Means 119 is preferably electrical,
although it is possible to arrange for mechanical
rotation of valves 72,92. Means 119 includes a control
transmitter 120, and a control transformer and servo
122. Control transmitter 120 is driven by camshaft
34 at one-half engine speed (for a 4 cycle engine).
Such a control transmitter 120, through suitable
buffering networks which are well known, directly
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drives control transformer and servo 122 which rotates
valve 72. By adjusting the position of a stator 124 of
control transmitter 120, the starting of injection is
controlled. This is accomplished by adjusting the
timed positioning of shoulder ~2 of valve 72 relative
to cam 34 as to precisely when shoulder 82 begins to
block inlet 81 thus controlling the starting of in-
jection.
In the additional identical means 119, the
control transmitter, also driven by camshaft 34,
directly drives control transformer and servo 122 for
rotating valve 92. By adjusting stator 124 of control
transmitter 120, the stopping of injection is con-
trolled. This is accomplished by adjusting the timed
positioning of shoulder 102 of valve 92 relative to
shoulder 82 of valve 72 as to precisely when shoulder
102 stops blocking inlet 101 thus controlling the
stopping of injection. Electrical equipment for
supplying the above-described functions of means 119
is available from commercial sources such as AEROFLEX
and the SINGER INSTRUMENT COMPANY, both of the United
; States of America.
Another electrical means is possible for
continuously rotating rotors 72,92 and will be briefly
discussed. Such means comprises a digital system,
several types of which have been used successfully for
various applications requiring precision drives with
adjustable phase angles. Such a digital system may be
obtained from stepping motors of the type commercially
available from HAWKER-SIDDLEY DYNAMICS of Great Britain,
but do not have provisions for feedback corrections.
However, feedback loop equipment is commercially
available from DISC INSTRUMENT CORP. of the United
States of America.
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Rotating the valves 72,92 at one-half engine
speed will result in makin~ one injection of fuel per
two engine revolutions in a four cycle engine. A two
cycle engine would have valves 72,92 rotating at crank
speed since injection frequency is at crank frequency.
~ The arcuate lengths Ll, L2 and L3 of shoulders 82,82a
; and 102, respectively, may be expressed in rotational
degrees. Thus, by controlling the position and dimen-
~-~ sions Ll,L2, of the blocking shoulders 82,82a relative
to cam 34, the starting and stopping of pilot injection
and the starting of main injection can be controlled,
; and, by controlling the position of shoulder 102
relative to shoulders 82,82a, the stopping of injection
can be controlled.
Electrical means are employed to determine
the start of injection as well as to determine the
quantity of fuel injected. Such means are well known
and are not the subject of this invention. These means
usually include a power source, sensing devices,
actuators, and the like, and take into account inlet
manifold pressure and temperature, engine speed and
load, and even fuel temperature.
~`~ A well known logic system, for example, the
universal fuel injection system, UFIS, developed for
~ 25 the military for use in track type or armored vehicles,
- may be used for actuating a fuel pump control system.
The UFIS reads and interprets vehicle data such as ; -
- engine speed, boost or manifold pressure, engine
;; temperature, ambient temperature, altitude, load, etc.
The UFIS is powered by the vehicular power system,
`;~ e.g., a twelve (12) or twenty-four (24) volt system or
the like. The UFIS logic requires relatively low
milliamperage. Thus, the signal produced by the UFIS
logic must be matched to provide an appropriate UFIS
input to control transmitter 120. UFIS type logic can
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also provide the appropriate adjustment to stator 124
for controlling the position of shoulders 82,82a,
relative to cam 34 and the position of shoulder 102
relative to shoulders 82,32a as discussed above.
Figure 5 illustrates an alternative where
three valves are utilized as a means for starting and
stopping pilot injection and main injection. However,
the two valve apparatus is preferred over the three
valve apparatus. A first va:Lve 300 includes a first
blocking shoulder 301 of a first size for starting and
stopping pilot injection. A second valve 302 includes
a second blocking shoulder 303 of a second size greater
than the first size for starting main injection, and a
third valve 304 includes a third klocking shoulder 305
of a third size greater than the first and second sizes
for stopping main injection. All three valves 300,
302, 304 are continuously rotated at constant speed and
function as previously discussed with the sole dif-
-ference being that shoulder 301 (for starting and
stopping pilot injection) and shoulder 303 (for starting
main injection~ are on separate valves 300,302, re-
spectively, whereas in the preferred embodiment,
shoulder 82 (for starting and stopping pilot injection)
and shoulder 82a for starting main injection) are on
~25 the same valve 72. The reason the three valve concept
: is not preferred is that it is more expensive and
bulky. Of course the three valves 300,302,304 can
obviously be independently rotated for adjustment as
previously described for the two valve apparatus and
has the advantage of including the ability to adjust
the timing between the end of pilot injection and the
beginning of main injection.
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Industrial Applicability
With the parts assembled as set forth above,
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transfer pump 16 maintains a system pressure at about
30-35 psi. Means 119 rotate valves 72,92 continuously
at the same constant rate. Fuel enters housing 24 at
port 56 and flows to cavity 100 via conduit 20. The
fuel continues through conduit 22 and returns to tank
14 via conduits 22a,22b which include valves 72,92
respectively.
Camshaft 34 and lobe 32 rotate and cause
plunger 36 to reciprocate between positions "A" and
lQ "B". When plunger 36 blocks conduit 20 and continues
toward position "B" pilot injection can occur depending
now on the timed sequential and simultaneous positioning
of shoulders 82 and 102. First in the sequence, shoulder
102 rotates to block inlet 101 but fuel continues to
tank 14 via conduit 22a. Second in the sequence,
shoulder 82 simultaneously rotates to block inlet 81 as
shoulder 102 continues to block inlet 101 and fuel is
trapped in housing 24. Further downward movement of
plunger 36 greatly compresses fuel in cavity 100
;~ 20 forcing the fuel past check valve 49 to be pilot in-
jected through port 42. Next in the sequence after
- pilot injection endsj as plunger 36 contlnues toward
position "B" shoulder 82a blocks outlet 83 and main
injection begins. Subsequently, and as plunger 36
continues toward position "B", shoulder 102 rotates
-~ past inlet 101 and main injection stops as fuel resumes
flowing to tank 14 via conduit 22b. Finally, shoulder~
82a also clears outlet 83 and fuel again flows to tank
14 via conduit 22a.
Plunger 36 then begins travel from position
"B" to position "A", but under these conditions no
; injection occurs since fuel in cavity 100 is not being
compressed. The abbve-described cycle repeats rapidly.
Signals from the logic to means 119 can
operate through stator 124 to rotatably drive
valves 72,92 and adjust the relative
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positions of valve shbulders 82, 82a and 102.
The foregoing has described an electrically
controlled fuel injection apparatus including con-
tinuously rotating valves for starting and stopping
pilot and main fuel injection.
It is anticipated that aspects of the present
invention, other than those specifically defined in the
appended claims, can be obtained from the foregoing
description and the drawings. Although the foregoing
illustrates the fuel injection apparatus of this
; invention in a fuel system having a unit injector
adjacent a respective cylinder, it is anticipated that
the apparatus can be incorporated into fuel systems
using other than such unit injectors including, but not
limited to, a multi-plunger pump assembly wherein
multiple plungers operate to inject fuel through a
" plurality of remote nozzles, or where a plurality of
unit pumps are connected to inject fuel through a
~- corresponding plurality of remote nozzles.
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