[0001] The invention relates to a fuel injector and to a method of electronically operating
a fuel injector.
[0002] Fuel injection systems are known which employ hydraulic adjustment means to alter
the timing of the injection phase of the cycle of operation of a set of injectors
mechanically driven from the crankshaft of an internal combustion engine, and the
hydraulic means may be responsive to the speed of the engine and/or the load imposed
hereon. While the prior art systems functioned satisfactorily in most instances, several
operational deficiencies were noted. For example, the hydraulic adjustment means functioned
effectively over a relatively narrow range of speeds, and responded rather slowly
to changes in the operating parameters of the engine. Also, problems were encountered
in sealing the hydraulic adjustment means, for a rotor-distributor pump was utilized
to deliver hydraulic fluid to each of the fuel injectors in the set employed within
the fuel injection system. In order to provide a hydraulic adjustment means responsive
to both speed and/or the load factor such as suggested in US Patent 3,951,117 granted
April 20, 1976 to Julius Perr, an intricate, multicomponent assembly is required,
thus leading to high production costs, difficulty in installation and maintenance,
and reduced reliability in performance.
[0003] US-A-3,951,117, and 4,134,549 to Julius Perr, disclose a fuel supply system including
hydraulic means for automatically adjusting the timing of fuel injection to optimize
engine performance. The system comprises an injection pump including a body having
a charge chamber and a timing chamber formed therein. The charge chamber is connected
to receive fuel from a first variable pressure fuel supply, and the timing chamber
is connected to receive fuel from a second variable pressure fuel supply, while being
influenced by pressure modifying devices. The body further includes a passage that
leads through a distributor which delivers the fuel sequentially to each injector
within a set of injectors.
[0004] A timing piston is reciprocabty mounted in the body of the injection pump in Perr
between the charge and timing chambers, and a plunger is reciprocably mounted in the
body for exerting pressure on the fuel in the timing chamber. The fuel in the timing
chamber forms a hydraulic link between the plunger and the timing piston, and the
length of the link may be varied by controlling the quantity of fuel metered into
the timing chamber. The quantity of fuel is a function of the pressure of the fuel
supplied thereto, the pressure, in turn, being responsive to certain engine parameters,
such as speed load. Movement of the plunger in an injection stroke results in movement
of the hydraulic link and the timing piston, thereby forcing fuel into the selected
combustion chamber. The fuel in the timing chamber is spilled, or vented, at the end
of each injection stroke into spill port and spill passage.
[0005] Thus, with the deficiencies of the known fuel injection systems utilizing hydraulic
adjustment means to control the timing of fuel injection clearly in mind, it is an
object of the present invention to provide a fuel injector wherein the timing phase,
and the subsequent injection phase, of the cycle of operation can be easily altered
in dependence upon any of one or more parameters of engine operation, utilizing existing
control units, which respond rapidly to several engine parameters in addition to engine
speed and load, and generate appropriate signals for an electronically controlled
valve associated with the fuel injector.
[0006] To this end, the invention proposes a fuel injector for an internal combustion engine
comprising a body having an axially extending bore, a primary pumping plunger and
a secondary plunger positioned within said bore for axial movement therein in response
to the movement of said primary pumping plunger, a nozzle situated at the end of said
bore remote from said primary pumping plunger, a timing chamber defined in said body
between said primary plunger and said secondary plunger, a metering chamber defined
in said bore between said secondary plunger and said nozzle, passages in said body
of said injector for receiving pressurized fuel and transmitting said fuel into said
timing chamber and said metering chamber, characterized in that it comprises an electronically
operated control element situated intermediate said passages and said timing chamber
and adapted to be selectively energized to regulate the timing of the discharge of
fuel from the metering chamber through the nozzle and to regulate the quantity of
fuel discharged through the nozzle, and to control the quantity of fuel stored in
said metering chamber subsequent to said discharge of fuel wherein said electromagnetic
control element controls the admission of fuel into said timing chamber for creating
a hydraulic link between said primary pumping plunger and said secondary element to
selectively hydraulically connect said primary pumping plunger and said secondary
plunger wherein said control element is at one of a closed or opened state to create
a pressure condition in said timing chamber to permit independent movement of said
primary pumping plunger relative to said secondary plunger during a portion of the
operation of the injector.
[0007] It is also an object of the present invention to provide a method of electronically
operating such a fuel injector to regulate both the timing and the metering functions
of said fuel injector and to respond more quickly to changes in the engine parameters,
the inertial effects attributable to the numerous components of the known hydraulic
adjustment means being eliminated.
[0008] To this end, the invention proposes a-method of operating the above fuel injector
which comprises the steps of:
a) introducing fuel at supply pressure into said passages and said chambers;
b) applying a force to the primary pumping plunger to move same axially in relation
to the operating cycle of the internal combustion engine; characterized in that it
further comprises the steps of:
c) supplying an electrical signal to the control valve means to seal the timing chamber
and form a hydraulic link between the primary plunger and secondary plunger and moving
them in concert;
d) discharging the fuel in the metering chamber through the nozzle in response to
the electrical signal; and
e) filling the metering chamber to a desired level prior to terminating the electrical
signal;
f) terminating the electrical signal to the control valve means to open the timing
chamber and break the hydraulic link between the plunger and element and moving said
primary pumping plunger independently of said secondary element.
[0009] The invention will now be described with reference to the accompanying drawing wherein:
- Figure 1 is a schematic diagram of a fuel injection system cofigured in accordance
with the principles of the invention;
- Figure 2 is a vertical cross-sectional view, on an enlarged scale, of a fuel injector
utilized within the system of Figure 1;
- Figures 3 to 7 schematically show the sequence of operational steps for the fuel
injector of Figure 2;
- Figure 8 is a graphical representation of the cam surface utilized to control the
movement of certain portions of the injector of the present invention, depicting cam
lift relative to degrees of crank angle rotation; and
- Figure 9 is a composite schematic representation of the cycle of operation of an
injector in the instant fuel injection system; the upper graph traces the movement
of the primary plunger versus the rotational movement of the crankshaft, while the
lower chart notes the sequence of events versus the rotational movement of the crankshaft.
[0010] Turning now to the drawings, Figure 1 schematically depicts the major components
of a fuel injection system employing an electronically operated control valve for
regulating the timing and metering functions of each injector within the system. The
system includes a fuel injector 10 that is supported by a support block 12 and is
controlled to deliver fuel through a nozzle 14 directly into the combustion chamber
(not shown) of an internal combustion engine 16. Although only one injector is shown,
it should be noted that a set of identical injectors is employed within the fuel injection
system, one injector being provided for each cylinder in the engine. The injector
10 is operated in synchronism with the operation of the engine through the reciprocal
actuation of a follower 20, the follower 20 being biased upwardly by a heavy duty
spring 18.
[0011] A cam 22 is secured to the camshaft 24 of the internal combustion engine 16. Cam
22 rotates at a speed which is a function of engine speed, for the camshaft is driven
via meshing gears 23, 25 from the crankshaft 26. The gear ratio of gears 23, 25 may
vary from engine to engine depending on various factors, including, inter alia, whether
the engine is a two-cycle or four-cycle engine. The crankshaft drives the piston (not
shown) within the combustion chambers of the engine 16 in the usual manner. A roller
27 rides along the profile of the cam, and a push rod 28 and rocker arm 30 translate
the movement of the roller into the application of axially directed forces upon the
follower 20 and the primary piston; the forces act in opposition to main spring 18
and vary in magnitude with the speed of the engine and the profile of the cam. The
cam profile is of particular importance to the operation of the injector and will
be discussed more fully in the discussion of Figures 8 and 9.
[0012] A reservoir 32 serves as a source of supply for the fuel to be dispensed by each
injector 10, and fuel is withdrawn from the reservoir by transfer pump 34. Filters
36, 38 remove impurities in the fuel, and distribution conduit 40 introduces the fuel,
at supply pressure, to each of the injectors 10. A branch conduit 42 extends between
distribution conduit 40 and block 12 and makes fuel, at supply pressure, available
for circulation through injector 10. The fuel that is not dispensed into a combustion
chamber in the engine is returned to the reservoir 32 via branch return conduit 44
and return conduit 46. A fixed orifice 48 is disposed in return conduit 46 to control
rate of return flow into the reservoir. Directional arrows and legends adjacent to
the conduits indicate the direction of fuel flow.
[0013] The fuel injection system of Figure 1 responds to several parameters of engine performance.
In addition to engine speed, which is reflected in the rate of rotation of the cam
22 secured upon camshaft 24, several sensors 50 are operatively associated with engine
16 to determine, inter alia, engine speed, temperature, manifold absolute pressure,
load on the engine, altitude, and air-fuel ratio. The sensors 50 generate electrical
signals representative of the measured parameters, and deliver the electrical signals
to an electronic control unit, or ECU. 52. The electronic control unit then compares
the measured parameters with reference values which may be stored within a memory
in the unit, takes into account the rotational speed and angular position of cam 22,
and generates a signal to be delivered to each injector. The signal, in turn, governs
the timing and metering functions of each injector. Leads 54, 56 and a connector 58
interconnect the electronic control unit 52 and the control valve 146 for the representative
injector shown in Figure 1.
[0014] Figure 2 depicts the components of a representative injector 10. The segment at the
left hand side of Figure 2 fits atop the segment at the right hand side of Figure
2.
[0015] Referring to the upper end of the injector 10, a fragment of the rocker arm 30 is
visible bearing against the enlarged upper end of follower 20, and main spring 18
rests on support block 12 and urges the follower 20 upwardly. A primary pumping plunger
62 is joined to the lower end of follower 20, the follower'20 and primary pumping
plunger 62 moving as a unitary member. A cylindrical guide 64 insures the axial movement
of follower 20, while a seal guide 66 provides a seal and insures the axial movement
of primary pumping plunger 62. It is to be understood that block 12 and guides 64,
66 may be formed as an integral unit. A slot 68 in the follower 20 cooperates with
stop 60 to prevent the follower 20 and spring 18 from becoming disassembled from the
remainder of the injector prior to association with the rocker arm 30 and to limit
the downward travel of follower 20.
[0016] An internally threaded jacket 70 is screwed into engagement with the mounting block
12, and the interior of the jacket surrounds the distinct segments that comprise the
body of the fuel injector 10. Each segment of the body is generally cylindrical in
shape, is generally executed in metal, has a central bore and has passages drilled.
or otherwise formed therethrough, in alignment with the central bore and the passages
of the adjacent segment. Thus, in Figure 2, fuel injector 10 includes an elongated
sleeve 72, a disc-like segment 74, and a spring cage 76 that communicates with nozzle
14. A seal 78 seals the juncture between the block 12 and the threaded jacket 70.
Supply passages 80, 82, of which there are two pairs of each, only one each of which
are shown, extend through the various segments, and an annular cavity 84 is defined
beneath the seal guide 66 and the upper end of the axial passages. The lowermost ends
of passages 80, 82 extend radially inwardly to terminate in annulus 83. The passages
80, 82 (a total of four passages arranged around piston 62) also extend radially inwardly
to terminate in annulus 85, spaced above annulus 83 in the sleeve of the injector.
[0017] A cylindrical recess 86 is located in the lower end of the primary pumping plunger
62, and a stud 88 is located within the recess to form a spring retaining member.
A secondary plunger 90 is axially movable within the central bore of the sleeve 72,
and a valve seat insert 92, with a recess 94 in its upper surface, is situated at
the upper end of the secondary plunger. A spring 96 extends between stud 88 and the
insert 92 and constantly maintains a downwardly directed biasing force upon the secondary
plunger. A variable volume timing chamber 98 is defined between the lower end of plunger
62 and the upper end of secondary plunger 90. Secondary plunger 90 slides freely within
the bore of sleeve 72 and primary plunger 62 travels within the bore 97 of support
block 12.
[0018] A passage 99 extends axially through the valve seat insert 92 to communicate with
cross-hole passage 100 which opens into annulus 1 02.formed on the surface of secondary
plunger 90. A first check valve 104, preferably in the form of a poppet valve, is
normally biased by spring 106 against a valve seat 108 formed in passage 100 to control
fluid communication between chamber 98 and passage 100. The spring 106 is seated in
a guide cavity 110 in the secondary plunger 90.
[0019] An annulus 112 is formed in the outer surface of secondary plunger 90 at approximately
the mid-section thereof, annulus 112 communicating with a cross-hole passage 114 and
an axial passage 116. A second check valve 118 in the secondary plunger is biased
against its valve seat 120 by a spring 121 disposed in a cavity 122 formed in the
plunger 90. Valve 118 thus controls communication between passage 116 and inverted
L-shaped passages 124, 126, of which there are two each, which extend axially through
the lower end of the secondary plunger. The passages open into an annulus 125 formed
in the exterior surface of plunger 90. A variable volume metering chamber 128 is defined
between the lower end of secondary plunger 90 and the disc-like segment 74.
[0020] A disc 130 fits within a recess 132 at the upper end of segment 74, and the disc
is of sufficient area to seal off one end of metering chamber 128 to prevent gases
in the cylinders in the engine from blowing back into the injector in the event the
nozzle 14 fails to seal. The recess 132 opens downwardly into a plurality of passages
134, 136, sets of which are arranged circumferentially around the central axis of
injector 10, passage 136 communicating with nozzle 14. The upper end of a needle valve
144 is secured to a spring retaining member 142, and a spring 138 is disposed between
element 74 and member 142 to bias valve 144 downwardly against a valve seat 145 to
prevent fuel from being dispensed from- the nozzle 14. Only when the pressure in passage
136 significantly exceeds the combined forces of the spring biasing pressure and the
supply pressure is the needle valve unseated to permit a fine atomized spray of fuel
to be issued from nozzle 14..
[0021] Branch conduit 42 introduces fuel, at supply pressures of 3,5 to 14 kg/cm
2, into support block 12 through conduit 43 and thence into injector 10. An electronically
operated control valve 146 is disposed between conduit 42 and conduit 43 to control
both the timing and the metering functions for injector 10 as will be more fully explained
hereafter. Branch conduit 43, as suggested by the diagonally extending dotted lines,
communicates fuel at supply pressure with timing chamber 98 when the control valve
146 is open.
[0022] The functioning of the several components of the fuel injector of Figure 2 will best
be appreciated by reviewing the sequence of operation shown in Figures 3 to 7. However,
in order to better portray the sequence of operational events, license has been taken
in depicting the various elements of the injector 10. For example, the segments housed
within jacket 70 are shown as a unitary member, the guides 64, 66 and disc 130 have
been omitted, the follower 20 and the primary pumping piston 62 have been shown as
a unitary member, etc.
[0023] Turning now to Figure 3, which shows a convenient but arbitrarily selected starting
point for the cycle of operation, control valve 146 is shown in its normally opened
condition to allow fuel at supply pressure in the branch conduit 42 access to supply
passage 43 and the timing chamber 98. Actually, an equilibrium pressure condition
exists (supply pressure) as the primary plunger 62 has ceased its upward motion and
is prepared to start its downward motion due to the action of camshaft 24 and cam
22 on plunger 62 as will be seen from a description of Figures 8 and 9. The timing
chamber 98 and metering chamber 128 previously have been filled with fuel as will
be seen from a description of Figures 6 and 7. With the control valve 146 open, fuel
is free to flow into and out of timing chamber 98. As shown in Figure 3, check valve
104 is biased against its seat by spring 106 and check valve 118 is biased against
its seat by spring 121.
[0024] The primary pumping plunger 62 and the secondary plunger 90 sealingly engage the
central bores 97, 69, respectively, of the injector, and the spring 96 continuously
imparts a downward bias upon plunger 90. A precise amount of fuel is present in metering
chamber 128 due to a prior metering operation, to be described in conjunction with
the description of Figures 6 and 7, and the trapped fuel acts against spring 96. With
the control valve 146 opened, timing chamber 98 is in its equilibrium condition, so
that when rocker arm 30 forces follower 20 and primary pumping plunger 62 downwardly,
at the rate suggested by the arrow beneath plunger 62, fuel is forced out of timing
chamber 98 through passages 43, 42. The secondary plunger is unaffected by such movement
and remains stationary under the bias of spring 96 and trapped fluid in metering chamber
128. The duration of the period during which valve 146 is maintained in its opened
condition relative to a fixed reference is a variable quantity determined by the electronic
control unit 52 in response to actual engine conditions and independent of the travel
of plunger 62. Thus, the instant at which the valve 146 is closed, and the timing
chamber 98 isolated from the supply passage 42, can be adjusted relative to the fixed
reference, e.g., the top dead center (TDC) position of the crankshaft 26, over fairly
broad limits.
[0025] Figure 4 shows the various components of the fuel injector 10 at the instant that
injection starts through nozzle 14 due to the high pressure (several hundred bar)
created by the trapped fluid in timing chamber 98 and metering chamber 128. During
the downward travel of plunger 62 from the arbitrarily selected starting position
of Figure 3, and a very short period of time before the instant of injection shown
in Figure 4, the valve 146 is closed as described above. With the valve closed, timing
chamber 98 is sealed, and the continued downward movement of plunger 62 causes the
downward movement of secondary plunger 90 to rapidly increase the pressure of the
fuel trapped in chamber 128. The downward movement of the secondary plunger 90 pressurizes
the fuel in chamber 128 to a level sufficient to unseat needle valve 144 and permits
a fine spray of pressurized fuel to be discharged through the pin holes in nozzle
14.
[0026] The second check valve 118 remains seated during the injection phase of the cycle
of' operation due to the fact that the high pressure below check valve 118 created
by the pressure in metering chamber 128, as communicated thereto by passages 124,
126, is greater than the supply pressure in passages 80, 82 and cross-hole 114.
[0027] Figure 5 shows the various components of the fuel injector immediately after the
termination of the injection shown in Figure 4, Figure 5 illustrating the "dumping"
or pressure relieving phase of operation. In this phase the control' valve 146 is
still closed and the primary pumping plunger 62 is approaching its limit of downward
travel, as suggested by the small arrow beneath the plunger. In this phase, the annulus
125 is in fluid communication with annulus 83 thereby communicating the high pressure
in passages 124, 126, 136 with the supply pressure in passages 80, 82. As the pressure
in passages 124, 126, 136 approaches the supply pressure existing in passages 80,
82, the pressure on the needle valve is insufficient to hold valve 144 open and the
needle valve 144 is again seated against seat 145. The pressure build-up in passage
136 and metering chamber 128 is rapidly relieved, so that the undesirable dribble
of fuel through the nozzle is prevented.
[0028] At the same time, the pressure of the fuel in timing chamber 98, which has been intensified
by the downward movement of plunger 62, is relieved to permit the primary plunger
62 to complete its downward travel after the termina
- tion of injection and precludes excess pressure on the parts of the injector subject
to the pressure in timing chamber 98. More specifically, the annulus 102 is in fluid
communication with annulus 85 thereby communicating passage 100 below valve 104 with
the supply pressure in passages 80, 82. The pressurized fuel in chamber 98, as compared
to supply pressure in passage 100, creates a pressure differential across first check
valve 104 to unseat check valve 104. Fuel flows from timing chamber 98, through check
valve 104, annulus 102, and annulus 85 back into axial passages 80, 82. Check valve
104 has been provided to check the flow of fuel from passage 80 to timing chamber
98, through annuli 85, 102, just prior to the metering phase of operation. If valve
104 did not seat, fuel flow from passage 80 to timing chamber 98 would preclude the
metering to be described below.
[0029] The direction of flow of pressurized fuel from both the timing chamber chamber 98
and the metering chamber 128 is indicated by directional arrows. After entering the
axial passages, the fuel is returned to reservoir 32 via conduits 44, 46 (Figure 1).
[0030] Figure 6 shows the various components of the fuel injector after the primary pumping
plunger 62 has completed its downward travel and has started its upward travel under
the urging of spring 18 to create the "metering" phase of operation. The control valve
146 is retained in its closed condition, and annulus 102 is out of communication with
annulus- 85, thereby sealing timing chamber 98. The fuel in timing chamber 98 is approximately
at supply pressure due to the dumping shown in Figure 5. First check valve 104, which
was unseated during the "dumping" phase of the cycle of operation, as shown in Figure
5 is again held against its seat 108 by spring 106 to prevent communication between
chamber 98 and passage 100.
[0031] As the primary pumping plunger 62 moves upwardly, as suggested by the arrow atop
the head of follower 20, the pressure in timing chamber 98 drops to a pressure level
below supply pressure as the volume of chamber 98 increases marginally. The pressure
of the fuel beneath secondary plunger 90 in metering chamber 128 is greater than the
combined forces of the fuel in chamber 98 and the biasing force of spring 96. The
secondary piston 90 thus follows the primary pumping piston 62 in its ascent because
of the net, upwardly directed pressure differential. During this early movement of
secondary plunger 90, while annuli 125, 83 are in alignment, fuel flows from passages
80, 82, through passages 124, 126, to metering chamber 128.
[0032] As the secondary plunger moves upwardly, the lower-most annulus 125 defined on the
plunger 90 moves out of alignment with annulus 83, thereby sealing metering chamber
128 from the annulus 83. The intermediate annulus 112, which opens into cross-hole
passage 114, stays in alignment with the lower portion of annulus 85. Consequently,
supply pressure in passages 42, 80, 82 is impressed on annulus 85, thence into annulus
112, and passage 114, to the upper portion of second check valve 118. This pressure
differential across check valve 118 created by the relatively high supply pressure
above check valve 118 as compared to the relatively low pressure in metering chamber
128, unseats check valve 118. Thus, fuel flows into metering chamber 128 through check
valve 118, through passages 124, 126, as shown by the arrows in Figure 6.
[0033] The quantity of fuel that flows into metering chamber 128 is proportional to the
volumetric displacement of plunger 90 created by the pressure differential across
plunger 90. The plunger 90 can only move in concert with plunger 62 while control
valve 146 is closed. In summarizing these relationships, it will be appreciated that
the quantity of fuel introduced into the metering chamber 128 is proportionally related
to the duration or interval, in crankshaft degrees, during which the control valve
146 is held closed after the start of the upward travel of secondary plunger 90. Obviously,
when the valve 146 is held closed by a signal from the electronic control unit 52
for the entire interval in crankshaft degrees allocated for metering, the chamber
128 will be filled with the maximum amount of fuel. When the valve 146 is held closed
by a signal from the electronic control unit for only half of the interval, defined
in degrees of crankshaft rotation, then the metering chamber will be half filled.
Other proportional relationships are available in accordance with the fraction of
the crankshaft rotational interval selected to hold valve 146 closed. This proportionality
will become more apparent during the discussion of Figures 8 and 9.
[0034] Figure 7 shows the various components of the fuel injector at the termination of
the metering phase of the cycle of operation. The metering phase is terminated by
terminating the electrical signal from electronic control unit 52 to the control valve
146, which then returns to its normally opened condition. With valve 146 opened, the
fuel at supply pressure in passages 42, 43 and the fuel in timing chamber 98 quickly
establish an equilibrium condition at approximately supply pressure level. The pressure
differential across plunger 90 is removed and secondary plunger 90 is, in effect,
disconnected and cannot follow primary pumping plunger 62 as plunger 62 continues
its upward movement. With valve 146 opened, the combined forces of the fuel in timing
chamber 98 and spring 96 are greater than the force of the fuel; at supply pressure,
retained in metering chamber 128. Therefore, plunger 90 is "locked" or retained in
fixed position. The instant at which the signal to valve 146 is terminated is determined
by engine operating parameters sensed by the electronic control unit relative to the
number of degrees of angular rotation of the camshaft 24 as measured by the crankshaft
26 rotation from the above-described fixed reference, as determined by conventional
sensors. Primary pumping plunger 62 continues upwardly, following the cam surface,
under the urging of spring 18 independently of secondary plunger 90, as suggested
by the arrow atop follower 20 in Figure 7. When the primary pumping plunger 62 reaches
its uppermost position, as shown in Figure 3, then the cycle of operation for the
fuel injection can be repeated in the manner shown progressively in Figures 3 to 7.
[0035] Referring to Figures 8 and 9, Figure 8 illustrates, in graphic form, the profile,
or lift, of the cam surface of cam 22 (Fig. 1) relative to the number of degrees of
crankshaft rotation, and Figure 9 illustrates, in graphic form, the vertical motion
of primary pumping plunger 62 relative to the same number of degrees of crankshaft
rotation and the relationship thereto of the single electronic control unit pulse
which initiates injection and terminates metering. Both figures, Figure 9 particularly,
correlate the various phases of injector operation described in conjunction with the
description of Figures 3 to 7 with degrees of crankshaft rotation. From Figures 8
and 9, a very graphic illustration of the proportionality of the metering phase may
be seen. Thus the termination of the electronic control unit pulse to control valve
146 will be seen to be linearly related to the number of degrees of crankshaft rotation
after a preselected reference point (for example, top dead center).
[0036] Specifically describing Figure 8, there is illustrated the lift of the cam, or cam
profile surface plotted against the number of degrees of crankshaft rotation, and
includes various points (A, B, C, D) along the curve. The curve approaches point A,
which is the lowest point of the curve, and will be seen to correspond to the arbitrarily
selected starting position described in conjunction with the description of Figure
3. The curve progresses through the injection phase, between points B and C; the dumping
phase, between points C and D; and the metering phase, between points D and E. Point
E corresponds to the end of the metering phase and a point F corresponds for the next
sequence to point A for the previous sequence.
[0037] Figure 9 is a composite graphic representation of the operation of one injector 10
in the set of injectors employed in the instant fuel injection system. The upper graph
plots the movement, or stroke, of primary pumping plunger 62 along the vertical axis
against the degrees of rotational movement of the crankshaft 26; the rotational movement
being measured by sensors that provide a signal representative of crankshaft rotation
in degrees. The trace of the plunger 62 shows that the plunger instantaneously peaks,
then moves downwardly until it reaches a nadir position, and then linearly returns
upwardly to the peak position. For a two cycle engine, a complete cycle occurs within
360° of rotational movement of the crankshaft; for a four cycle engine, a complete
cycle occurs within 720° of rotational movement of the crankshaft.
[0038] The lower graph in Figure 9 plots the opening and closing of control valve 146 by
the electronic control unit, and other events, against the degrees of rotational movement
of the crankshaft 26. The leading edge of the signal to control valve 146 causes the
valve to change state from its normally opened state to its closed state, and the
trailing edge of the signal causes the valve to change state again and return to its
normally opened position. It will be noted that a single pulse from the electronic
control unit initiates the injection phase and terminates the metering phase, while
the internal configuration of the injector (annuli, check valves, etc.) terminates
the injection phase and initiates the metering phase.
[0039] The upper and lower graphs of Figure 9 may be correlated by following the progression
of steps indicated by reference characters A, B, C, D, E and F. It is to be understood
that the duration of the period A to D, in degrees, is determined by the sum of injection
timing variation and injection duration plus the duration of the damping operation.
It is believed that the determination of the duration of the period A to D is well
within the scope of one skilled in the art. The plunger 62 assumes its peak upward
position under the bias of main spring 18 at the start of the cycle of operation (Fig.
3). This is point A on the curve and, with the control valve .146 still in its normally
opened state, as seen at the bottom of Figure 9, the plunger 62 starts downwardly
under the force of rocker arm 30 pressing against follower 20.
[0040] During the course of the downward movement of plunger 62, the electronic control
unit 52 delivers a signal to valve 146, and closes the valve as described in conjunction
with the description of Figure 4. Point B on the curve designates the instant at which
injection occurs during the timing function due to the closing of the valve 146, while
point C indicates when the injection ceases due to the communication of annuli 102,
85 as described in conjunction with the description of Figure 5. The electronic control
unit can be adjusted, either manually or automatically, in accordance with actual
engine operating parameters, to shift the timing of the leading edge of the signal
relative to the downward movement of the plunger 62. Point B will then shift along
the curve to reflect such adjustments. The ability to adjust the instant at which
valve 146 is closed to start the injection function assists in more completely burning
the fuel discharged into each combustion chamber in the engine 16. Thus, the closure
of valve 146 starts the injection phase of the cycle of operation as shown in Figure
4.
[0041] The compression-injection phase of the cycle of operation lasts for the brief interval
B-C, the length of which is determined by the quantity of fuel which has been metered
into metering chamber 98. During the period B-C. the secondary plunger follows the
primary plunger downwardly and forces the fuel out of metering chamber 128 and through
nozzle 14. The plungers are'coupled through the sealed timing chamber 98 which forms
a hydraulic link between the two plungers.
[0042] Point C on the curve designates the cessation of the injection phase of the cycle
of operation and the period between points C-D represents the overtravel and dumping
portion of the cycle. At point C, while the control valve 146 remains closed, the
passages 124 and 126 in the secondary plunger 90 are in fluid communication with the
annuli 125, 83 to communicate metering chamber 128 and passage 136 with the supply
pressure in passages 80, 82 and vent, or dump, the pressurized fuel trapped in the
metering chamber 128 and the nozzle 14 back into the low pressure of axial passages
80, 82. The venting of the nozzle enables the needle valve to be re-seated and prevent
dribble of fuel through the nozzle into the combustion chamber.
[0043] Due to the alignment of annuli 102, 85, the pressure below check valve 104 is reduced
to supply pressure (below the pressure in timing chamber 98), and the upper check
valve 104 is unseated so that the pressure in the timing chamber 98 is reduced, or
dumped, to supply pressure, while the primary plunger is decelerating. The relationships
that exist at the instant of dumping the pressurized fuel from chamber 128, the nozzle
14, and chamber 98 are shown in Figure 5.
[0044] The downward travel of the primary pumping plunger 62 continues for the interval
C-D, or until the plunger 62 reaches its maximum travel. The overtravel of the plunger
62 beyond the termination of injection (point C) and end of dumping (point D) provides
sufficient time to equalize the pressures in the injector at supply pressure and to
provide the necessary range of timing and injection. When plunger 62 reaches point
D, the nadir of travel, and then starts to travel upwardly under the urging of main
spring 18, its return trip to its peak upward position occurs over a major portion
of the cycle of operation which corresponds to the metering phase (Figures 6 and 7).
[0045] The curve from point D through points E and F is substantially a linear curve having
a constant slope. The linear slope is achieved by a unique profile on the cam 22,
which slope is important to the proportional operation of the metering phase of operation.
Point E represents the instant that the metering function ceases and corresponds to
the termination of the signal from the electronic control unit. The termination of
the signal to control valve 146 causes the control valve to return to its normally
opened condition, which allows the timing chamber 98 to reach an equilibrium condition
with the fuel at supply pressure in passage 42. Spring 96 locks secondary plunger
90 in fixed position in metering chamber 128, and plunger 62 can move independently
in response to the application of forces by rocker arm 30 and spring 18. This termination
is described in conjunction with the description of Figure 7.
[0046] The metering function can be terminated at any point along the slope D-F; if the
metering function is terminated shortly after the primary plunger starts its return
trip, then the interval D-E will be shorter than the interval from E-F. The greater
the interval D-E, the greater the volume of fuel admitted into metering chamber 128.
It is to be noted that the linearity of the portion of the curve between points D
and F permits a direct, proportional relationship between the amount of fuel metered
and the number of degrees of camshaft rotation. The interval, in degrees of rotation,
between points D and F represents the maximum volume of fuel which can be metered,
any lesser amount is a direct function (proportional) to the number of degrees of
rotation the control- valve remains closed after point D. Thus, if point E occurs
one-half the number of degrees between D and F, one-half the quantity of fuel is metered.
[0047] It should be noted that the metering function can occur, potentially, over more than
half the cycle of operation. This "stretching out" of the metering function increases
the opportunity to accurately fill the metering chamber 128 to the desired level.
As described above, the slope of the curve D-F through the metering function is linearly
proportional to the degrees of angular rotation of the crankshaft 26. Thus, if the
metering function is assumed to occur, potentially, over 300° of angular rotation
for the crankshaft for a two cycle engine, then the termination of the signal from
electronic control unit 52 to control valve 146 after 150° of angular rotation, would
allow the metering chamber 128 to be half-filled. Alternatively, if the termination
of the signal from electronic control unit 52 to control valve 146 occurred after
75° of rotation, metering chamber 128 would be a quarter-filled. Obviously, the metering
chamber can be filled to an infinite variety of fractional levels.
[0048] It will be readily apparent to the skilled artisan that the foregoing embodiment
of this fuel injection system is susceptible of numerous changes without departing
from the basic inventive concepts. For example, the primary pumping plunger 62 and
follower 20 could be formed as a unitary plunger, and the check valves 104, 112, which
are preferably shown as poppet valves, could be disc valves, ball valves, etc. The
control valve 146, which is shown as a gate valve responsive to electromagnetic forces,
could assume diverse other forms. The profile of cam 22 can also be altered to adjust
the duration of the metering function and the rate of return of the primary plunger
62. Also, the spring 96 could be joined to the central bore of the injector, and need
not have one end seated in a cavity in the primary pumping plunger; the key consideration
is the ability of the spring 96 to always exert a downward force on the secondary
plunger and, when necessary, at the end of the metering operation, lock plunger 90
in fixed position.
1. A fuel injector (10), for an internal combustion engine comprising a body having
an axially extending bore (97), a primary pumping plunger (62) and a secondary plunger
(90) positioned within said bore for axial movement therein in response to the movement
of said primary pumping plunger (62), a nozzle (14) situated at the end of said bore
(97) remote from said primary pumping plunger (62), a timing chamber (98) defined
in said body between said primary plunger (6.2) and said secondary plunger (90), a
metering chamber (128) defined in said bore between said secondary plunger (90) and
said nozzle (14), passages (42, 43, 80, 82) in said body of said injector (10) for
receiving pressurized fuel and transmitting said fuel into said timing chamber (98)
and said metering chamber (128), characterized in that it comprises an electronically
operated control element (146) situated intermediate said passages (42, 43, 80, 82)
and said timing chamber (98) and adapted to be selectively energized to regulate the
timing of the discharge of fuel from the metering chamber (128) through the nozzle
(14), and to regulate the quantity of fuel discharged through the nozzle, and to control
the quantity of fuel stored in said metering chamber (128) subsequent to said discharge
of fuel wherein said electromagnetic control element (146) controls the admission
of fuel into said timing chamber (98) for creating a hydraulic link between said primary
pumping plunger (62) and said secondary plunger (90) to selectively hydraulically
connect said primary pumping plunger (62) and said secondary plunger (90) wherein
said control element (146) is at one of a closed or opened state the latter to create
a pressure condition in said timing chamber (98) to permit independent movement of
said primary pumping plunger (62) relative to said secondary plunger (90) during a
portion of the operation of the injector.
2. A fuel injector according to Claim 1, characterized in that said pressure condition
is an equilibrium pressure condition.
3. A fuel injector according to Claims 1 or 2, characterized in that said secondary
plunger (90) is biased in a normal position.
4. A fuel injector according to Claim 3, characterized in that the lower end of said
primary pumping plunger (62) has a cavity (86) defined therein and the upper end of
said secondary plunger (90) has a recess (94) defined therein, the injector further
including spring means (96), the opposite ends of said spring means being seated in
said cavity (86) and said recess (94).
5. A fuel injector according to Claim 2, characterized in that it comprises a first
check valve (104) interconnected to control fuel flow between said timing chamber
(92) and said passages for periodically eliminating said hydraulic link between said
primary pumping and said secondary plungers (62, 90).
6. A fuel injector according to Claim 5, characterized in that said first check valve
(104) is unseated to release fuel from said timing chamber (92) into said passages
when the secondary plunger (90) approaches its most downward position.
7. A fuel injector according to Claim 2, characterized in that said secondary element
(90) has elongated axially extending passages (124, 126) defined in its lower end,
said axially extending passages (124, 126) opening at one end into said metering chamber
(128), and said passages (124, 126) momentarily dumping fuel at high pressures back
into said passages (80, 82) in the injector body when the injection phase of the cycle
of operation is terminated.
8. A fuel injector according to Claim 6, characterized in that said secondary plunger
(90) has an annulus (112) defined near it mid-section, said annulus (112) leading
into a cross-hole (114) which communicates with a short axial passage (116), said
short axial passage (116) communicates with said elongated axially extending passages
(124, 126) that open into said metering chamber (128), a second check valve (118),
and a spring (121) to normally bias said second check valve (118) against its seat
(120) to prevent communication between said annulus (112) and said metering chamber
(128), said second check valve being unseated only during the metering phase of the
cycle of operation to allow fuel at supply pressure from the passages (80, 82) in
the injector body to enter the annulus (112) and proceed downwardly into the metering
chamber (128) through said axially extending passages (124, 126).
9. A fuel injector according to Claim 1, characterized in that the volumes of said
timing chamber (98) and said metering chamber (128) are varied during each cycle of
operation of said fuel injector in accordance with engine operating conditions.
10. A fuel injector according to Claims 1, 2 or 8, characterized in that a portion
of said operation is metering and said metering chamber volume is varied linearly
during said metering portion.
11. A fuel injector according to Claim 3, characterized in that it comprises spring
means (96) situated in said central bore (97) for biasing the secondary plunger (90)
toward said nozzle (14).
12. The fuel injector according to Claim 1 characterized in that one of said passages
(82) communicates said timing chamber (98) or said metering chamber (128) to a reservoir
(32) or to a return conduit (44).
13. The fuel injector according to Claim 1 characterized in that one of said passages
(82) communicates both said timing chamber (98) and said metering chamber (128) to
a reservoir or to a return conduit (44).
14. A method of operating a fuel injector (10) of Claim 1, said method comprising
the steps of:
a) introducing fuel at supply pressure into said passages (42, 43, 80, 82) and said
chambers (98, 128);
b) applying a force to the primary pumping plunger (62) to move same axially in relation
to the operating cycle of the internal combustion engine;
characterized in that it further comprises the steps of:
c) supplying an electrical signal to the control valve means (146) to seal the timing
chamber (98) and form a hydraulic link between the primary plunger (62) and secondary
plunger (90) and moving them in concert;
d) discharging the fuel in the metering chamber (128) through the nozzle (14) in response
to the electrical signal; and
e) filling the metering chamber (128) to a desired level prior to terminating the
electrical signals;
f) terminating the electrical signal to the control valve means (146) to open the
timing chamber and break the hydraulic link between the primary pumping plunger (62)
and the secondary plunger (90) and moving said primary pumping plunger independently
of said secondary plunger.
15. A method according to Claim 14, characterized in that it further comprises the
step of aligning passages formed in the secondary plunger with the passages (42, 43,
80, 82) in the body of the injector (10) after discharging the fuel so that excess
fuel trapped in the nozzle (14), metering chamber (128) and timing chamber (98) can
be readily vented.
1. Un injecteur (10) de carburant pour un moteur à combustion interne, comprenant
un corps ayant un alésage (97) s'étendant axialement, un plongeur de pompage primaire
(62) et un plongeur secondaire (90) positionné à l'intérieur dudit alésage de façon
à pouvoir s'y déplacer axialement en réponse au déplacement dudit plongeur de pompage
primaire (62), une buse (14) située à l'extrémité dudit alésage (97) éloignée dudit
plongeur de pompage primaire (62), une chambre (98) de fixation du point d'injection
formée dans ledit corps entre ledit plongeur primaire (62) et ledit plongeur secondaire
(90), une chambre de dosage (128) formée dans ledit alésage entre ledit plongeur secondaire
(90) et ladite buse (14), des passages (42, 43, 80, 82) formés dans ledit corps dudit
injecteur (10) pour recevoir du carburant sous pression et transmettre ledit carburant
à ladite chambre (98) de fixation du point d'injection et à ladite chambre de dosage
(128), caractérisé en ce qu'il comprend un élément de commande (146) actionné électroniquement
situé entre lesdits passages (42, 43, 80, 82) et ladite chambre (98) de fixation du
point d'injection et agencé de manière à pouvoir être sélectivement excité pour régler
le moment de l'éjection du carburant hors de la chambre de dosage (128) par la buse
(14) et pour régler la quantité de carburant éjectée par la buse et pour commander
la quantité de carburant emmagasinée dans ladite chambre de dosage (128) à la suite
de ladite éjection de carburant, en ce que ledit élément de commande (146) électromagnétique
commande l'admission de carburant dans ladite chambre (98) de fixation du point d'injection
pour créer une liaison hydraulique entre ledit plongeur de pompage primaire (62) et
ledit plongeur secondaire (90) pour relier sélectivement hydrauliquement ledit. plongeur
de pompage primaire et ledit plongeur secondaire, et en ce que ledit élément de commande
(146) est dans l'un de deux états, fermé ou ouvert, ce dernier état servant à créer
une condition de pression dans ladite chambre (98) de fixation du point d'injection
permettant un déplacement indépendant dudit plongeur de pompage primaire (62) par
rapport audit plongeur secondaire (90) pendant une partie du fonctionnement de l'injecteur.
2. Un injecteur de carburant selon la revendication 1, caractérisé en ce que ladite
condition de pression est une condition de pression en éequilibre.
3. Une injecteur de carburant selon la revendication 1 ou 2, caractérisé en ce que
ledit plongeur secondaire (90) est solicité à une position normale.
4. Un injecteur de carburant selon la revendication 3, caractérisé en ce qu'une cavité
(86) est formée dans l'extrémité inférieure dudit plongeur de pompage primaire (62)
et un évidement (94) est formé dans l'extrémité supérieure dudit plongeur secondaire
(90), l'injecteur comprenant, en outre, des moyens élastiques (96), les extrémités
opposées desdits moyens élastiques étant en appui dans ladite cavité (86) et dans
ledit évidement (94).
5. Un injecteur de carburant selon la revendication 2, caractérisé en ce qu'il comprend
une première soupape de retenue (104) montée de manière à commander l'écoulement du
carburant entre ladite chambre (98) de fixation du point d'injection et lesdits passages
pour supprimer périodiquement ladite liaison hydraulique entre lesdits plongeurs de
pompage primaire et secondaire (62, 90).
6. Un injecteur de carburant selon la revendication 5, caractérisé en ce que ladite
soupape de retenue (104) est écartée de son siège pour décharger le carburant depuis
ladite chambre (98) de fixation du point d'injection dans lesdits passages lorsque
le plongeur secondaire (90) s'approche de sa position basse extrême.
7. Un injecteur de carburant selon la revendication 2, caractérisé en ce que des passages
allongés (124, 126) s'étendant axialement sont formés dans l'extrémité inférieure
dudit plongeur secondaire (90), lesdits passages (124, 126) s'étendant axialement
débouchant, à une extrémité, dans ladite chambre de dosage (128) et lesdits passages
(124, 126) déchargeant momentanément le carburant à haute pression en retour dans
lesdits passages (80, 82) formés dans le corps de l'injecteur lorsque la phase d'injection
du cycle do fonctionnement est terminée.
8. Un injecteur de carburant selon la revendication 7, caractérisé en ce que ledit
plongeur secondaire (90) comporte un espace annulaire (112) formé au voisinage de
son milieu, ledit espace annulaire (112) débouchant dans un passage transversal (114)
qui communique avec un court passage axial (116), ledit court passage axial (116)
communiquant avec lesdits passages allongés (124, 126) qui débouchent dans ladite
chambre de dosage (128), une seconde soupape de retenue (118) et un ressort (121)
pour solliciter normalement ladite seconde soupape de retenue (118) en appui contre
son siège (120) afin d'empêcher la communication entre ledit espace annulaire (112)
et ladite chambre de dosage (118), ladite seconde soupape de retenue n'étant écartée
de son siège que pendant la phase de dosage du cycle de fonctionnement, pour permettre
au carburant à la pression d'alimentation des passages (80, 82) formés dans le corps
de l'injecteur de pénétrer dans l'espace annulaire (112) et de s'écouler vers le bas
jusque dans la chambre de dosage (128) par lesdits passages (124, 126) s'étendant
axialement.
9. Un injecteur de carburant selon la revendication 1, caractérisé en ce que les volumes
de ladite chambre (98) de fixation du point d'injection et de ladite chambre de dosage
(128) sont modifiés au cours de chaque cycle de fonctionnement dudit injecteur de
carburant en conformité avec les conditions de fonctionnement du moteur.
10. Un injecteur de carburant selon la revendication 1, 2 ou 8, caractérisé en ce
qu'une partie du fonctionnement est une opération de dosage et ledit volume de la
chambre de dosage varie linéairement pendant ladite partie de dosage.
11. Un injecteur de carburant selon la revendication 3, caractérisé en ce qu'il comprend
des moyens élastiques (96) situés dans ledit alésage central (97) pour solliciter
ledit plongeur secondaire (90) en direction de ladite buse (14).
12. L'injecteur de carburant selon la revendication 1, caractérisé en ce que l'un
desdits passages (82) fait communiquer ladite chambre (98) de fixation du point d'injection
ou ladite chambre de dosage (128) avec un réservoir (32) ou avec un conduit de retour
(44).
13. L'injecteur de carburant selon la revendication 1, caractérisé en ce que l'un
desdits passages (82) fait communique à la fois ladite chambre (98) de fixation du
point d'injection et ladite chambre de dosage (128) avec un réservoir ou avec un conduit
de retour (44).
14. Un procédé d'utilisation d'un injecteur de carburant (10) de la revendication
1, ce procédé comportant les étapes qui consistent:
a) à introduire du carburant à la pression d'alimentation dans lesdits passages (42,
43; 80, 82) et lesdites chambres (98, 128);
b) à appliquer une force au plongeur de pompage primaire (62) pour le déplacer axialement
en rapport avec le cycle de fonctionnement du moteur à combustion interne;
caractérisé en ce qu'il comprend, en outre, les étapes qui consistent:
c) à appliquer un signal électrique aux moyens formant valve de commande (146) pour
obturer la chambre (98) de fixation du point d'injection et établir une liaison hydraulique
entre le plongeur primaire (62) et le plongeur secondaire (90) et de façon que ceux-ci
se déplacent à l'unisson;
d) à éjecter le carburant contenu dans la chambre de dosage (128) par la buse (14)
en réponse au signal électrique; et
e) à remplir la chambre de dosage (128) à un niveau désiré avant la fin du signal
électrique;
f) à terminer l'application du signal électrique aux moyens formant valve de commande
(146) pour ouvrir la chambre de fixation du point d'injection et rompre la liaison
hydraulique entre le plongeur de pompage primaire (62) et le plongeur secondaire (90)
et à déplacer ledit plongeur de pompage primaire indépendamment dudit plongeur secondaire.
15. Une procédé selon la revendication 14, caractérisé en ce qu'il comporte, en outre,
l'étape qui consiste à aligner des passages formés dans le plongeur secondaire avec
les passages (42, 43, 80, 82) formés dans le corps de l'injecteur après éjection du
carburant de sorte que le carburant en excès emprisonné dans la buse (14), la chambre
de dosage (128) et la chambre (98) de fixation du point d'injection peut être facilement
évacué.
1. Kraftstoff-Einspritzventil (10) für eine Brennkraftmaschine, mit einem Gehäuse,
das eine axial verlaufende Bohrung (97). aufweist, einem primären Pumpkolben (62)
und einem sekundären Kolben (90), der in der Bohrung angeordnet ist und in Abhängigkeit
von der Bewegung des primären Pumpkolbens (62) axial bewegbar ist, einer Düse (14),
die an dem vom primären Pumpkolben (62) abgewandten Ende der Bohrung (97) angeordnet
ist, einer Zeitgeberkammer (98), die in dem Gehäuse zwischen dem primären Pumpkolben
(62) und dem sekundären Kolben (90) gebildet ist, einer Zumeßkammer (128), die in
der Bohrung zwischen dem sekundären Kolben (90) und der Düse (14) gebildet ist, im
Gehäuse des Einspritzventils (10) gebildeten Kanälen (42, 43, 80, 82), die unter Druck
stehenden Kraftstoff empfangen und diesen Kraftstoff an die Zeitgeberkammer (98) und
die Zumeßkammer (128) weiterleiten, dadurch gekennzeichnet, daß es ein elektronisch
betätigtes Steuerelement (146) aufweist, das zwischen den Kanälen (42, 43, 80, 82)
und der Zeitgeberkammer (98) angeordnet ist und wahlweise erregbar ist, um die Zeitsteuerung
der Kraftstoffabgabe aus der Zumeßkammer (128) durch die Düse (14) zu regeln und um
die Menge des durch die Düse abgegebenen Kraftstoffes zu regeln und um die Menge des
Kraftstoffes, die in der Zumeßkammer (128) im Anschluß an die Kraftstoffabgabe gespeichert
wird, zu steuern, daß das elektromagnetische Steuerelement (146) die Kraftstoffzufuhr
in die Zeitgeberkammer (98) steuert, um eine hydraulische Verbindung zwischen dem
primären Pumpkolben (62) und dem sekundären Kolben (90) zu erzeugen und dadurch den
primären Pumpkolben (62) und den sekundären Kolben (90) wahlweise hydraulisch zu verbinden,
und daß sich das Steuerelement (146) in geschlossenem oder offenem Zustand befindet,
um in letzterem Zustand eine Bedingung in der Zeitgeberkammer (98) zu erzeugen, die
während eines Teiles des Betriebes des Einspritzventiles eine unabhängige Bewegung
des primären Pumpkolbens (62) relativ zum sekundären Kolben (90) zuläßt.
2. Kraftstoff-Einspritzventil nach Anspruch 1, dadurch gekennzeichnet, daß die besagte
Druckbedingung ein Druckgleichgewicht ist.
3. Kraftstoff-Einspritzventil nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß
der sekundäre Kolben (90) in eine Normalstellung vorgespannt ist.
4. Kraftstoff-Einspritzventil nach Anspruch 3, dadurch gekennzeichnet, daß das untere
Ende des primären Pumpkolbens (62) einen darin gebildeten Hohlraum (86) aufweist und
das obere Ende des sekundären Kolbens (90) eine darin gebildete Ausnehmung (94) aufweist,
wobei das Einspritzventil außerdem Federmittel (96) umfaßt, deren entgegengesetzte
Enden in dem Hohlraum (86) und der Ausnehmung (94) sitzen.
5. Kraftstoff-Einspritzventil nach Anspruch 2, gekennzeichnet durch ein erstes Rückschlagventil
(104), das den Kraftstoffluß zwischen der Zeitgeberkammer (92) und den Kanälen so
steuert, daß die hydraulische Verbindung zwischen dem primären Pumpkolben (62) und
dem sekundären Kolben (90) periodisch aufgehoben wird.
6. Kraftstoff-Einspritzventil nach Anspruch 5, dadurch gekennzeichnet, daß das erste
Rückschlagventil (104) zur Freigabe von Kraftstoff aus der Zeitgeberkammer (92) an
die Kanäle abgehoben wird, wenn der sekundäre Kolben (90) sich seiner untersten Stellung
nähert.
7. Kraftstoff-Einspritzventil nach Anspruch 2, dadurch gekennzeichnet, daß der sekundäre
Kolben (90) langgestreckte, axial verlaufende Kanäle (124, 126) aufweist, die in seinem
unteren Ende gebildet sind, wobei die axial verlaufenden Kanäle (124, 126) an einem
Ende in die Zumeßkammer (128) münden, und daß diese Kanäle (124, 126) unter hohem
Druck stehenden Kraftstoff kurzzeitig an die im Gehäuse gebildeten Kanäle (80, 82)
zurückführen, wenn die Einspritzphase des Betriebszyklus beendet ist.
8. Kraftstoff-Einspritzventil nach Anspruch 6, dadurch gekennzeichnet, daß der sekundäre
Kolben (90) einen Ringraum (112) aufweist, der nahe seines Mittelabschnittes gebildet
ist, wobei der Ringraum (112) in eine Querbohrung (114) mündet, die mit einem kurzen
axialen Kanal (116) in Verbindung steht, wobei der kurze axial Kanal (116) mit den
langgestreckten axial verlaufenden Kanälen (124, 126) verbunden ist, die in die Zumeßkammer
(128) münden, und daß ein zweites Rückschlagventil (118) vorgesehen ist, das von einer
Feder (121) normalerweise gegen seinen Sitz (120) gedrückt wird, um eine Verbindung
zwischen dem Ringraum (112) und der Zumeßkammer (128) zu unterbrechen, wobei das zweite
Rückschlagventil nur während der Zumeßphase des Betriebszyklus vom Sitz abgehoben
wird, damit Kraftstoff unter Zufuhrdruck aus den im Gehäuse gebildeten Kanälen (80,
82) in den Ringraum (112) eintreten und nach unten durch die axial verlaufenden Kanäle
(124, 126) in die Zumeßkammer (128) fortschreiten kann.
9. Kraftstoff-Einspritzventil nach Anspruch 1, dadurch gekennzeichnet, daß die Volumina
der Zeitgeberkammer (98) und der Zumeßkammer (128) während jedes Betriebszyklus des
Kraftstoff-Einspritzventils in Abhängigkeit von Betriebsbedingungen der Brennkraftmaschine
veränderbar sind.
10. Kraftstoff-Einspritzventil nach Anspruch 1, 2 oder 8, dadurch gekennzeichnet,
daß ein Teil des Betriebes ein Zumessen ist und daß das Volumen der Zumeßkammer während
des Zumeßvorganges linear verändert wird.
11. Kraftstoff-Einspritzventil nach Anspruch 3, dadurch gekennzeichnet, daß in der
zentralen Bohrung (97) Federmittel (96) angeordnet sind, die den sekundären Kolben
(90) in Richtung auf die Düse (14) vorspannen.
12. Kraftstoff-Einspritzventil Nach Anspruch 1, dadurch gekennzeichnet, daß einerder
Kanäle (82) die Zeitgeberkammer (98) oder die Zumeßkammer (128) mit einem Reservoir
(32) oder einer Rückführleitung (44) verbindet.
13. Kraftstoff-Einspritzventil nach Anspruch 1, dadurch gekennzeichnet, daß einer
der Kanäle (82) sowohl die Zeitgeberkammer (98) wie auch die Zumeßkammer (128) mit
einem Reservoir oder einer Rückführleitung (44) verbindet.
14. Verfahren zur Betätigung eines Kraftstoff-Einspritzventils (10) nach Anspruch
1 mit folgenden Schritten:
a) Einführen von Kraftstoff unter Zufuhrdruck in die Kanäle (42, 43, 80, 82) und die
Kammern (98, 128);
b) Ausüben einer Kraft auf den primären Pumpkolben (62), um diesen in Abhängigkeit
vom Betriebszyklus der Brennkraftmaschine axial zu bewegen;
gekennzeichnet durch folgende weiteren Schritte:
c) Abgabe eines elektrischen Signals an die Steuerventilmittel (146), um die Zeitgeberkammer
(98) abzudichten und eine hydraulische Verbindung zwischen dem primären Pumpkolben
(62) und dem sekundären Kolben (90) herzustellen und sie gemeinsam zu bewegen;
d) Abgabe von Kraftstoff an die Zumeßkammer (128) durch die Düse (14) in Abhängigkeit
von dem elektrischen Signal;
e) Auffüllen der Zumeßkammer (128) auf ein vorgegebenes Niveau vor Beendigung der
elektrischen Signale;
f) Beendigung der Abgabe des elektrischen Signals an die Steuerventilmittel (146),
um die Zeitgeberkammer zu öffnen und die hydraulische Verbindung zwischen dem primären
Pumpkolben (62) und dem sekundären Kolben (90) zu unterbrechen und den primären Pumpkolben
unabhängig vom sekundären Kolben zu bewegen.
15. Verfahren nach Anspruch 14, gekennzeichnet durch den folgenden weiteren Schritt,
daß in sekundären Kolben gebildete Kanäle zu den Kanälen (42, 43, 80, 82) im Gehäuse
des Einspritzventils (10) nach Abgabe des Kraftstoffes ausgerichtet werden, sodaß
in der Düse (14), der Zumeßkammer (128) und der Zeitgeberkammer (98) gefangener überschüssiger
Kraftstoff rasch abgeführt werden kann.