Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
~L 170903
The invention is gerlerally related -to distribu-tor
type fuel injection pumps for controlling the quantity and
timing of injection of fuel into the cylinder of an engine,
and in particular is related to a distributor type fuel
injection pump in which the metering and timiny of injection
of fuel is controlled by a single electromagnetic control valve.
The instant application is related to U.S. Patent No.
4,281,792 granted August 4, 1981 and U.S. Patent No. 4,235,374
grantedNove~ber 25, 1980. The instant application is also
related to U.S. Patent No. 4,357,925 of Frank Woodruff,
issued November 9, 1982 and U.S. Patent No. 4,367,715 of Edwin
Ben Watson, issued January 11, 1983. Further, this
application is related to Canadian Patent Application Serial
No. 389,121, 389,101 and 389,111, all filed on October 30, 1981.
Distributor fuel injection pumps in which the time
of injection and the period of injection are both controlled
mechanically or hydraulically are well known in the art.
However, recent advances in electronics have resulted in the
development of electronic fuel control systems which are
capable of very accurately computing fuel quantity and timing
requirements in response to one or more operational parameters
of the engine. These electronic systems include electronic
control units which are capable of not only computing the
required fuel quantity, but also the time at which the fuel
is to be injected into the cylinder to optimize the engine's
performance. One such electronic control unit is disclosed
in U.S. Patent No. 4,379,332 granted on April 5, 1983. Another
electronic control unit is disclosed in Patent No. 4,219,154.
Also recently, the invention described in the above-referenced
U.S. Patent Nos. 4,281,792 and 4,235,374 were developed, the
application of the invention being initially in the field of
unit injectors, however, it has been discovered that inventive
concepts described in the above-referenced application could
also be applied to distribution pumps to great advantage.
The resulting application of that unit injector technology to
distribution pumps has resulted in the invention of the
present application.
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~ 17090 3
According to the present invention there is provided
a fuel control,system for a multicylinder internal combustion
engine including a housing having a fuel inlet and a plurality
of fuel outlets, one for each cylinder of the engine. Means
is operatively connected to the engine for pressurizing fuel
between the inlet and outlet ports. The pressurizing means
includes a cam element, a body having an axially extending
central bore and a primary pumping plunger operatively
associated with the cam element and a secondary free element
positioned within the bore for at least partial axial movement
therein. A passageway situated at the end of the central
bore remote from the primary pumping plunger and in fluid
communication with each of the fluid outlets in sequence. A
timing chamber is defined in the body between the primary
pumping plunger and the secondary element. A metering chamber
is defined in the body between the secondary element and the
passageway. Passages in the body receive pressurized fluid
and transmit the fluid into the timing chamher and the metering
chamber, the passages including a first passage radially
extending through the body and terminating at the bore within
the timing cham~er and a second passage terminating at the
first passage and adapted to receive fuel from a fuel source.
A control valve means is provided for controlling the timin~
of the discharge of fuel from the metering cham~er through
the passageway and the quantity of fuel stored in the metering
chamber subsequent to the discharge of fuel, the control valve
means having an armature movable in response to control
signals extending through the first passage and terminating
in a ball wherein when the control valve means is activated
by the control signals the ball is moved to seal the first
passage and when the control valve means is not activated
the ball is moved to reopen the first passage. The pressure
of the fuel within the timing chamber further acts to urge
the ball into engagement with the first passage. A
distribution head assembly is provided which has an inlet
passage in communication with the passageway and having a
portion thereof rotated in synchronism with the cam element
and adapted to distribute fuel from the metering chamber
to each of the fuel outlets in succession.
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1 1709~3
More specifically, -the invention is a distributor
type fuel injection pump in which the injection timing and
fuel metering is controlled by a sing:Le electromagnetic control
device, wherein the fuel for an injection into a particular
cylinder is preme~ered prior to that injection. In a cycle
of operation, the rotation of the eng:ine causes the rotation
of a cam mounted on a shaft which is xotating at a speed which
is half the speed of a four-stroke cycle engine rotation.
The cam operates to drive a piston in a cavity, the cavity
also forming a metering chamber and a timing chamber, the two
chambers being separated by a free piston. As the piston is
being driven into the chamber, in particularly the timing
chamber, the point of injection is selected by an electronic
control unit and a pulse is generated to either energize or
de-energize a control valve. This creates a hydraulic link
between the driving piston or primary piston and the free
piston, thereby driving the floating piston into the chamber.
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~ 170903 587-81-0040
This pressurizes the fuel in the metering chamber,
which fuel is then injected to a particular cylinder
determined by the position of the distributor head.
After injection has taken place, the driving piston is
allowed to move out of the chamber, thereby permitting
the free piston to move away from the bottom of the
chamber under influence of the supply pressure. This
allows fuel to flow into the metering chamber. The fuel
may flow into the metering chamber in accordance with a
pressure-time metering concept with a restricted oriface
or a volumetric metering concept determined by the
position of the piston. When the proper amount of fuel
has been allowed into the metering chamber, the control
valve is de-energized and the subsequent movement of the
driving piston out of the chamber allows fuel to enter
into the timing chamber. Thus, the system is prepared
for the next injection of fuel into a different cylinder
of the engine.
With the system of the present invention, a single
control solenoid, and a single pulse from an electronic
control unit, is utilized to control the initiation of
injection of fuel into a particular cylinder and also to
control the amount of fuel that is to be injected into
the next cylinder of the engine. The control valve may
be very fast acting and thus precise control of timing
and metering may be accomplished with the system of the
present invention.
Brief Description of the Drawings
FIGURE 1 is a perspective view, partially in cross
section, of a distributor fuel pump for an internal
combustion engine incorporating the features of the
present invention; and
~170903 587-8l-0o4o
--4--
FIGURE 2 is a cross-sectional view of a modified
form of the inventive concepts of FIGURE 1 and
particularly showing the control assembly and distri-
bution assembly of the system of the present invention.
Detailed Description of a Preferred and Modified
Embodiment of the Present Invention
Referring now to Figure 1, there is illustrated a
distribution type fuel pump 10 which is particularly
adapted to be utilized in conjunction with controlling
the time of injection and amount of injection of fuel
into an internal combustion engine, particularly of the
diesel type. Specifically, the pump 10 includes a gear
type driving mechanism 12, a timing and premetering
assembly 14, the fuel output from the timing and
premetering assembly 14 being fed to a distribution head
16 which controls the particular cylinder to which each
pulse of fuel is fed in the internal combustion engine.
The control of the timing and premetering assembly 14 is
accomplished by a electromagnetic solenoid control unit
18.
Referring to the specific details of the various
sections of the distribution pump shown in Figure 1, it
is seen that the driving mechanism 12 is basically a gear
assembly including a main gear 20 which is driven from
the engine with which the distribution pump is
associated. The gear 20 is driven at half the speed of
the engine thereby rotating one revolution per two revo-
lutions of the engine. The gear 20 is mounted on a shaft(not shown) which drives a second gear 22 which can be of
reduced diameter relative to the gear 20. Gear 22 in
turn drives a gear 24 which is mounted on a shaft 26, the
shaft 26 rotating at the same speed as that of the gear
1 ~70903
20, the particular application illustrated being utilizea
in a four cycle engine. The rotation of the shaft 26 will
drive a cam 28.
The cam is utilized to drive the timing and
premetering assembly 14 in a manner to be described. ~t should
be noted that the onfiguration and operation of the timing
and premetering section 14 is very similar to that aescribed
in the above-referenced and U.S. Patents r~O. 4,235,374 and
No. 4,281,792. For a very detailed description of the
operation of the timing a premetering section, reference is
made to that application and U.S. Patent. However, for
purposes of illustration, certain details of the assemhly 14
will be described herein.
Fuel is introduced to the distribution pump by means
of a conduit 36, the conduit 36 supplying fuel to the internal
case of the dist:ibution pump. The supply of fuel is f~d
from conduit 36 through a passageway 38 formed in the body of
the timing and premetering section 14. As is seen from the
drawing, this fuel is fed to a metering chamber 40 by means
of a passage~ay 42 through a check-valve 44. Fuel is also
fed to the control valve 18 by means of a passageway 48,
the output of the control valve being fed to a timin~ chamber
50 by means of a passageway 52. The metering chamber 40 and
the timing chamber 50 are separated by means of a floating
piston 56. The rotational motion of the shaft 26 and cam 28
are translated into reciprocating motion by means of a
driving piston 58. The piston 58 is urged toward the cam
element 28 by means of a spring 62. The fuel pulse output
from the metering chamber is fed to the distribution head 16
by means of a passageway 64.
The distribution head is driven by the same shaft
which is driving the gear 22. Thus, the output of the
distribution head 16 is synchronized with the operation of
the cam 28.
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58~-81-0040
The distribution head 16 includes a plurality of
output connectors 70, one connector being connected to
each cylinder of the internal combution engine being
controlled. An embodiment of a distribution head will be
described in conjunction with the description of Figure
2.
In operation, and assuming that a preselected amount
of fuel has been metered into metering chamber 40, and
the piston 58 is at its downmost position, the shaft 26
is rotated and the cam surface forces driving piston
upwardly against the action of the spring 62. During
this part of the operation, the control valve 18 is in a
state such that fuel can flow from the timing chamber 50
out through passageway 52 and back to the source of fuel
supply. At the point in the rotation of the engine at
which injection is to occur, the control solenoid 18 is
energized to preclude fuel flow out of the timing chamber
and thus pressurize the fuel in the timing chamber. The
continued motion of the driving piston 58 pressurizes the
fuel in the metering chamber 40 and causes pressurized
fuel to be injected from an injection connected to a line
(not shown) connected to one of the output connectors 70,
depending on the position of the distributor head. This
drives piston 56 upwardly until such time as a passageway
72 is put into fluid communication with the passageway
shown in the free piston 56. This dumps fuel from the
metering chamber 40 and reduces the pressure therein. At
approximately the same time, the passageway which
contains the check valve 74 is put into fluid
communication with the timing chamber to permit fuel to
be dumped from the timing chamber as the piston 58 is
driven further into the timing chamber.
When the piston 58 is fully extended into the timing
chamber, the cam surface then starts to permit the piston
58 to be withdrawn. With the control solenoid still in
the energized state, the withdrawing of piston 58 creates
1 ~709~3 587-81-0040
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a reduced pressure in the timing chamber to cause the
floating piston 56 to follow the downward motion of the
driving piston 58. The draws fuel into the metering
chamber 40 through the passageway 42. When the desired
amount of fuel i5 metered into the metering chamber 40,
the control solenoid 18 is de-energized which stops the
downward motion of the free piston 56 and thereby stops
metering of fuel into the metering chamber 40. Further
downward motion of the piston 58 causes fuel to be
metered into the timing chamber by means of passageway
52. The cycle is then complete and ready for the next
timing and injection cycle for the next cylinder.
Referring now to Figure 2, there is illustrated some
schematic details of the control solenoid 18 and the
distribution head 16, the details being shown in
schematic fashion to illustrate the principle of the
present invention. As was described in conjunction with
Figure 1, a cam 80, shown schematically for a single
injection cycle, drives piston 58 upwardly into the
timing chamber 50. ~he control solenoid 18 is
illustrated as having a coil 82 which electromagnetically
controls the position of an armature 84, the end of the
armature having formed thereon a control valve shown in
the form of a ball 86. In the position shown, the coil
82 is de-energized and piston 58 is driven upwardly into
the timing chamber 50. At the point that injection is to
occur, solenoid 82 is energized to pull ball 86 to the
right and shut off a passageway 90. Prior to the ball
shutting off the passageway 90, fuel is permitted to flow
from the timing chamber, through passageway 42 and back
to the supply by means of a passageway 38. When ball 86
is seated, the fuel in the timins chamber 50 is
pressurized which in turn pressurizes the fuel in
metering chamber 40. With further upward movement of
piston 58, the free piston 56 is driven upwardly to cause
1 1709~ ~ 587-81-0040
fuel to be pressurized in the distribution head 16. This
pressurized fuel causes a valve, including a ball 92,
which ball 92 is unseated to force pressurized fuel out
to the engine cylinder by means of a passageway 96. The
distribution head includes a shaft 98 which is rotated in
synchronism with the cam 80, thus distributing each pulse
of fuel ~o the respective cylinders. In the particular
embodiment illustrated in Figure 2, the cylinder
associated with conduit 96 is provided a pulse of fuel
and the cylinder associated with a conduit ]00 is
provided a pulse of fuel one engine revolution later than
that provided in the cylinder connected to 96.
It will be readily apparent to the skilled artesian
that the foregoing description of the embodiments of the
present invention may be modified in many ways and the
invention should not be limited by the above description.
Rather, the scope of the invention should be determined
by the scope of the appended claims.
