U.S. patent number 3,575,145 [Application Number 04/773,607] was granted by the patent office on 1971-04-20 for method and apparatus for injecting fuel into the cylinders of a multicylinder piston-type internal combustion engine.
This patent grant is currently assigned to Sulzer Brothers Limited. Invention is credited to Anton Steiger.
United States Patent |
3,575,145 |
Steiger |
April 20, 1971 |
METHOD AND APPARATUS FOR INJECTING FUEL INTO THE CYLINDERS OF A
MULTICYLINDER PISTON-TYPE INTERNAL COMBUSTION ENGINE
Abstract
Fuel injection apparatus for multicylinder engines comprising a
fuel pump, delivery lines to the individual cylinders, separate
means to measure the volume of fuel flowing through those lines,
and means to adjust the injection pressure in those lines or the
injection opening times therefrom into the individual
cylinders.
Inventors: |
Steiger; Anton (Illnau, Zurich,
CH) |
Assignee: |
Sulzer Brothers Limited
(Winterthur, CH)
|
Family
ID: |
4412139 |
Appl.
No.: |
04/773,607 |
Filed: |
November 5, 1968 |
Foreign Application Priority Data
|
|
|
|
|
Nov 10, 1967 [CH] |
|
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15812/67 |
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Current U.S.
Class: |
123/357; 123/478;
123/501; 137/101.21; 239/71; 123/458; 123/494 |
Current CPC
Class: |
F02D
41/3809 (20130101); F02D 41/008 (20130101); Y10T
137/2531 (20150401) |
Current International
Class: |
F02D
41/34 (20060101); F02D 41/38 (20060101); F02d
005/00 () |
Field of
Search: |
;123/32,32 (E)/ ;123/32
(E-1)/ ;123/119,140 ;137/99,101.9,101.21 ;239/71,74,435,455 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Goodridge; Laurence M.
Claims
I claim:
1. Fuel injection apparatus for a multicylinder piston-type
internal combustion engine comprising means to pump fuel, a
separate fuel line connecting the pumping means to each cylinder of
the engine, an injector valve in each fuel line, separate means to
measure in each fuel line the flow of fuel therethrough and to
generate a signal representative thereof, means to compare said
signals, and means to adjust the setting of said injector valves in
accordance with the result of said comparison.
2. Fuel injector apparatus according to claim 1 wherein said
comparison means effect comparison of the signals representative of
fuel flow through all of said fuel lines but one against the signal
representative of fuel flow through said one fuel line.
3. Fuel injection apparatus according to claim 1 wherein said
comparison means develop a signal representative of the average
flow of fuel through said fuel lines and wherein said adjusting
means adjust the settings of said injector valves in accordance
with departures of the fuel flow representative signals of said
fuel lines respectively from said average flow representative
signal.
4. Fuel injection apparatus according to claim 1 wherein said
separate means to measure the flow of fuel comprise volumetric
motors and means to detect motion of said motors.
Description
The present invention pertains to a method for the introduction of
fuel into the working cylinders of a multicylinder piston-type
internal combustion engine. In accordance with the invention the
quantities of fuel injected into the individual cylinders in given
time intervals are measured during operation of the engine and
corrections are introduced into the injection in dependence of the
measurements made, these corrections serving to equalize the
quantity of fuel supplied to the individual cylinders.
In the apparatus of the invention for practice of the method
thereof in an engine having plural cylinders and an injection
system including at least one fuel pump with fuel lines leading to
the individual cylinders, measuring devices are provided in the
fuel lines leading to the individual cylinders, these devices
serving to measure the volume of fuel passing through those lines.
Moreover, corrective devices are provided, allocated to the
individual cylinders, and which serve to adjust the fuel supply to
those cylinders.
In multicylinder piston-type internal combustion engines difficulty
is experienced in equalizing the quantities of fuel supplied to the
separate cylinders. Thus, large differences can appear in the
quantities of fuel delivered to the individual cylinders by the
volumetric fuel pumps now commonly employed, these difficulties
being especially troublesome at high injection pressures. This
produces unequal thermal loading of the cylinders with danger of
mechanical overloading of individual cylinders. The result is to
impose a lower limit of safe loading than would otherwise be
necessary.
It has already been proposed to employ time-controlled valves for
control of the injection into the individual cylinders. These
valves open the fuel delivery lines for precisely measured
intervals of time having a duration of a few milliseconds and
thereupon close again. The fuel is drawn from storage reservoirs
which are fed from a feed pump. This mode of operation has the
particular advantage that electrically operated valves can be used,
and this produces a simplification in the mechanical construction
of the apparatus. It is, however, subject to the shortcoming that
the quantities of fuel which achieve injection during the specified
time intervals may undergo substantial variation one from one
cylinder to another because for example of the various nozzle cross
sections of the individual injectors.
It is an object of the invention to provide a method and apparatus
by means of which these disadvantages are minimized and which makes
possible a uniform distribution of fuel to the individual
cylinders. Simultaneously, the invention makes possible the use of
the time-controlled injection valves and consequently, a
substantial simplification of the engine consistently with a
uniform supply of fuel to all cylinders at all load levels imposed
on the engine.
In accordance with the invention it is possible to vary the
injection pressure or the injection time duration to the individual
cylinders in accordance with correction values. Which of these
possibilities is preferable in an individual case depends to a
large extent on the construction of the injection system.
Advantageously the correction values are applied in a time-delayed
manner. In this way the supplementary control provided by the
correction signals is made to be a stable one.
As to the apparatus, the measurement devices may take the form of
volumetric motors having rotors built into the fuel delivery lines,
the motion of these rotors being monitored by scanning devices.
Preferably the rotors take the shape of gear pumps and scanning
devices are devices which operate without electrical contacts.
Thus, they may operate magnetically, inductively, or capacitively.
With this construction it is possible for the complete measurement
device for any fuel line to be in a closed housing having no
mechanically movable parts on the exterior thereof to be sealed
off. At the high pressures involved a sealing of, for example, a
shaft passing to the exterior of the housing would be a difficult
problem.
The correction devices may take the form of means for adjustment of
the injection pressure at the individual cylinders. Thus,
adjustable throttling devices may be employed as correction
elements, these throttling devices being disposed, for example, in
the fuel delivery lines. They may however be disposed on the
suction side of plural fuel pumps allocated to the cylinders. Such
throttling devices make possible a simple adjustment of the
streaming resistance of the individual hydraulic lines and
injection valves.
It is also possible to employ correction devices which serve
mutually to change the swept volumes of volumetric fuel pumps of
the individual cylinders.
Owing however to the uniformization of the fuel feed achieved, the
invention has important advantages also in the case of mechanically
or hydraulically actuated time-controlled injection valves.
In the several fuel lines, time-controlled valves may be arranged,
which may be electromagnetically operated for example. In this way,
as previously mentioned, a simple construction of the engine can be
achieved, in which the cam shafts heretofore required with their
cam drives can be eliminated.
For time-controlled injection valves, the correcting devices may
take the form of control means effecting a mutual variation of the
open times of the several valves, the open time of a valve
otherwise open too long being shortened while that of a valve
otherwise open too short a time is lengthened. It is thus possible
to obtain a design that, besides exceptional simplicity, has the
further advantage that it can be actuated in simple manner by an
electronic controller.
It is also possible to provide a controller that makes a comparison
of the values taken by measurement at individual cylinders and
actuates the correcting means through control signals according to
the comparative data obtained. This controller may determine the
deviations of the readings of the several cylinders from the
reading of a cylinder serving as master cylinder. Or it may form a
mean of the readings at the various cylinders, determine the
deviations of the several cylinders from that means, and set up the
control signals accordingly.
In this way it is possible to provide the engine with a
continuously and precisely operating control wherein, depending on
the nature of the deviations to be expected, either the one or
another type of control may have special advantages.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be further explained in terms of a number of
presently preferred nonlimitative exemplary embodiments and with
reference to the accompany drawings in which:
FIG. 1 is a diagram of a diesel engine having three cylinders and
incorporating fuel control apparatus according to the invention,
with manual setting of throttling means;
FIG. 2 is a transverse sectional view of one form of fuel measuring
apparatus according to the invention;
FIG. 3 is a diagrammatic representation of another form of
apparatus according to the invention in conjunction with a diesel
engine;
FIGS. 4 to 7, are diagrams useful in explaining the apparatus of
FIGS. 1 and 3;
FIG. 8 is a further diagrammatic showing similar to that of FIGS. 1
and 3 but illustrating the apparatus of the invention in
conjunction with an engine having volumetric injection pumps of
modern type;
FIG. 9 is a block diagram of an electronic controller for the
apparatus of FIG. 3; and
FIGS. 10 and 11 show two different forms for the correction signal
generator 110 of FIG. 9.
Like reference characters denote similar elements of structure
throughout the general FIGS.
DESCRIPTION OF PREFERRED EMBODIMENTS
In FIG. 1, a diesel engine 1 having three cylinders a, b, c is
provided with a fuel pump 2. By way of a pressure regulator 3, pump
2 feeds fuel lines 4, 5 and 6 leading to cylinders a, b, c. In fuel
lines 4 to 6, measuring means 7 are arranged, connected to
indicating instruments 8. Electromagnetically actuated injection
valves 9 are arranged in the fuel lines 4 to 6, just upstream of
the several cylinders, and preferably at the outlets of the lines.
Manually adjustable throttling means 10 are also provided in lines
4 to 6. When the injection system includes separate fuel reservoirs
associated with the individual cylinders, the throttling means 10
for each cylinder are arranged between its reservoir and the
injection valve 9. The electromagnetic injection valves 9 are
controlled from an injection controller 11 by way of electric
signal lines 12, 13, 14. Controller 11 receives a set value signal
from a line 15, representative for example of a desired engine
speed, and an actual value signal via signal line 16 from the
output side of the engine. The signal on line 16 may represent for
example engine speed, or some other operating variable. In the
embodiment shown, the engine 1 drives an electric generator 17. In
addition, the controller 11 may be connected by a signal line 18
(shown dotted) to the pressure regulator 3.
During operation of the engine, the pump 2 feeds fuel at high
pressure, e.g., up to 1,000 kg./cm..sup.2 or more, into the fuel
lines 4 to 6. The pressure regulator 3 either holds the pressure in
the fuel lines 4 to 6 constant or, if it is equipped to handle the
signal on line 18, it may adjust that pressure according to
operating conditions. The regulator 3 may for example act on the
pump 2 by way of a signal line 19. By way of signal lines 12 to 14,
the controller 11 delivers control signals to the valves 9, so that
they are opened at specified times and for specified time
durations. Upon opening of an injection valve, the fuel in injected
into the combustion chamber of the cylinder in question at the fuel
line pressure. In this process it is possible either to keep the
pressure in the fuel lines constant by operation of the pressure
regulator 3 and to adjust the open time of the injection valves to
the instantaneous load on the engine, or else the injection time
may be held constant and the injected fuel volume may be varied by
control of pressure in the fuel lines 4 to 6 with the aid of the
regulator 3.
In the embodiment shown in FIG. 1, the readings of the several
measuring means 7 may be read off at intervals on the indicating
instruments 8. If major deviations in the flow of fuel fed to the
individual cylinders thus appear, the throttling means 10 can be
adjusted manually to equalize the deliveries. If for example the
flow of fuel carried by one of the lines 4 to 6 is greater than
that of the others, its throttling means 10 will be adjusted in
closing direction, and vice versa.
FIG. 2 shows a preferred embodiment for the measuring device 7. Tow
gears 21 in mesh with each other are disposed in a housing 21,
inserted into a fuel line such as the line 4. The two gears form a
volumetric hydraulic motor. Except for the line 4, housing 20 is
closed on all sides, and no shafts pass from the gears to the
outside of the housing. For development of a signal representative
of the fuel flowing through the line, scanning means 22 are
provided inside housing 20. The housing 20 may for example be made
of nonmagnetic material and the gears 21 of ferromagnetic material.
In that case, the scanning means 22 may include an electromagnetic
coil with a core, the passing of the individual teeth of the nearer
gear setting up electrical impulses in the coil. Alternatively the
gears 21 and housing 20 may be made of an insulating material, the
ends of the teeth being provided with electrically conductive
material. The scanning means 22 may then include a coil to which
alternating current is supplied. When a tooth passes, the
electrical impedance of the coil is varied, and this can be
utilized to set up an impulse.
The embodiment of FIG. 3 differs from that of FIG. 1 in that the
measuring means 7 of FIG. 3 are provided with output signal lines
30, 31, 32 leading to a controller 33, replacing the controller 11
of FIG. 1. The controller 33 modulates the control signals which it
delivers to lines 12 to 14 according to the data in signal lines 30
to 32. In the event of excessive supply of fuel to one cylinder,
its injection time is shortened accordingly, and vice versa.
FIGS. 4 to 7 illustrate control of fuel supply and correction
thereof in accordance with the invention by operation on the
pressure in the fuel line and by operation on the open time of the
injection valves. The injection times in the several cylinders a,
b, c are plotted along the horizontal time-axis t. The vertical
axis p represents the pressures in their respective fuel lines.
In FIG. 4, the basic quantity injected per operating cycle of the
engine cylinder and at a given load on the engine corresponds to
the rectangle M of altitude h and time duration M/h. Owing to
unlike streaming conditions in the lines 4 to 6 to the various
cylinders however, equal areas do not necessarily imply equal fuel
quantities. Upon an increase in load, the controller 11 of FIG. 1
or 33 of FIG. 3 lengthens the open time of the injection valves, so
that additional quantities of fuel are received, indicated by the
rectangles N, likewise of altitude h and of time duration N/h.
Correction for unequal deliveries to the various cylinders is made,
in the case of FIG. 1, by resetting the throttling means 10 in one
or more of the fuel lines with resulting changes of injection
pressure upstream of the injection valve which are indicated by the
areas 0 (added) and P (subtracted). That is, to increase the fuel
injected, as indicated by the added area 0 in FIG. 4a, the
throttling device 10 of the cylinder a is loosened to facilitate
the flow of fuel through line 4. To reduce the flow of fuel, as
indicated by the subtracted area P, the throttling device 10 on
line 6 is lightened, to further restrict the flow of fuel through
line 6.
The diagram of FIG. 4 corresponds for example to the embodiment of
FIG. 1. It is immaterial in this connection whether the throttling
means 10 are set by hand or automatically by a suitable control.
The representation in FIG. 4 does not attempt to reflect the
influence on the level of fuel pressure exerted by controller 11 on
pressure regulator 3 by way of signal line 18. The cylinder b,
whose injection flow is not corrected, acts as a master cylinder.
This means that its fuel flow is taken as a datum, and the fuel
deliveries to the other cylinders are adjusted to match it, with of
course some time delay. The meaning of FIG. 4 thus is that by
manual or automatic means, the throttles 10 on lines 4 and 6 are
adjusted to raise the pressure at the injector in line 4 by the
height of the area 0 and to reduce it at the injector in line 6 by
the height of the area P so as to obtain in cylinder a quantity of
injected fuel represented by the pressure-time product making up
areas M, N and O together, equal to the quantity of fuel injected
into cylinder b and which is represented in FIG. 4b by the sum of
the areas M and N. In cylinder c there is obtained an equal
quantity of injected fuel, but since the time rate of injection is
a different function of pressure, this equal quantity is
represented in FIG. 4c as the sum of the time-pressure products M
and N less the time-pressure product P, M and N having the same
areas in FIG. 4c as in FIG. 4a and 4b.
The diagram in FIG. 5 illustrates the operation of an embodiment of
the invention in which the basic control of injection rate as well
as the correction thereof as between cylinders are effected by
pressure variation. The open time of the injection valves is in
this case constant. Thus, the quantity of fuel injected into all
cylinders is, to a first order of approximation, that given by the
time-pressure product area M. Upon an increase in load, a quantity
of fuel is added represented by the supplementary area Q, this
addition being made by an increase of pressure, for example by
operation of the pressure regulator 3 in FIG. 1. In addition, for
correction of deficient injection to cylinders a and c, corrective
pressure increases represented by the heights of the areas O and P
in FIG. 5 are made by adjustment of the throttling devices 10 on
lines 4 and 6, the correction 0 being in the positive direction
(more fuel) and the correction P being in the negative direction,
i.e., a subtraction from area Q in FIG. 5c. FIG. 5 thus illustrates
operation of a fuel injection control system of the type shown in
FIG. 1, with pressure regulated as a function of load by the
pressure regulator 3 and with constant injection time.
In the diagram of FIG. 6, the injection pressure is kept constant,
and the adjustment for load as well as the correction as between
cylinders is made by varying the injection time. To a basic
injection flow M there is added upon increase of load the quantity
N, by a uniform extension of the injection time at all cylinders.
Additional corrections of injection time are made, represented by
areas R (positive) at cylinder a and S (negative) at cylinder
c.
The diagram of FIG. 6 corresponds to the embodiment of FIG. 3 with
a regulator 33 as illustrated in FIGS. 9 and 10.
Finally, FIG. 7 shows a diagram corresponding to injection control
for response to load change by control of injection pressure, and
correction as between cylinders by variation of injector open
time.
The embodiment of FIG. 3 may operate in this manner, if the
controller 33 thereof operates on pressure regulator 3 by way of
signal line 18 and thereby controls the time rate at which fuel is
injected while the injectors are open. The signals in lines 12, 13
and 14, which control the open times of the injection valves, then
carry the correction signals as well.
FIG. 8 illustrates application of the invention to diesel engines
having the usual now current volumetric injection pumps. The engine
1 is provided with injection pumps 80, each of which is assigned to
one of the fuel lines 4 to 6. The pumps 80 are driven by the cam
shaft of the engine, and are controlled from a control rod 81 by a
lever 82 of a controller 83.
The pumps 80 of FIG. 8 are volumetric pumps, intended to deliver a
constant volume of fuel at ever stroke, which volume is supposed to
be the same for the pumps of all three cylinders. Because of
manufacturing tolerances and differences and because of unavoidable
wear and tear however, unequal flow rates and leakage losses will
make their appearance, with the result that the volumes of fuel
reaching the several cylinders may come to differ from each other.
In the embodiment of FIG. 8 it is possible, according to the
invention, after reading at the indicating instruments 8 the data
on the measuring devices 7, to adjust the pump setting means 84
manually in such a way as to equalize the injection rates.
The setting means 84 may for example take the form of throttling
means arranged on the suction side of the pumps. Alternatively,
they may comprise racks which are coupled to rod 81 and which serve
in known manner to adjust the deliveries from the pumps.
FIG. 9 shows a block diagram of one form of controller usable as
the controller 33 in FIG. 3. For simplicity, the example of speed
control has been chosen, i.e., that in which the signal delivered
on line 16 is representative of engine speed. It will be understood
that with suitable modification of the controller, other control
variables may also be taken into account. In FIG. 9, the engine 1
is provided with a tachometer 101 and an engine driven pulse
generator or distributor 102. From the tachometer 13, a signal line
103 passes into controller 33. From the pulse generator 102, three
lines 104 lead to controller 33. Lines 103 and 104 correspond
substantially to the signal channel 16 indicated schematically in
FIG. 3. The function of the pulse generator 102 is to specify the
instant in time at which injection is to begin in each of the
cylinders.
The signal supplied at line 103 from tachometer 101 is compared in
a control element 105 with the engine speed set value signal on
line 15. In the comparator 105 there is generated a control signal,
which may for example be a direct-current voltage, representative
of the difference between the set value and actual value of engine
speed. The signal so generated in element 105 is delivered via line
106 through adders 107 to pulse generators 108. The pulse
generators are at the same time connected via signal lines 104 to
the pulse generator 102. The output signals of pulse generators 108
are delivered to signal lines 12 to 14 which lead to the several
injection valves 9. The adding devices 107 are connected by signal
lines 109 to a correction signal generator 110. The generator 110
receives as input signals from lines 30 to 32 the individual
cylinder error signals generated in the measuring devices 7, the
signals generated there being converted by converters 111 into
direct-current voltages for example. The converters 111 are
connected by signal lines 112, 113, 114 to the generator 110.
With the engine in operation, the tachometer 102 delivers a signal
representative of the instantaneous speed of the engine 1. The
pulse generator 102 delivers pulses at the phases of crankshaft
rotation when injection is to begin in each of the engine
cylinders. The comparator element 105 delivers a signal whose
instantaneous magnitude determines, to a first approximation for
all cylinders, the duration of the injection process, as a function
of the comparison in device 105 of the engine speed set value
signal arriving on line 15 and the engine speed actual value signal
arriving on line 103. The output signal on the three branches of
line 106 has superimposed thereon in the adders 107 the correction
signals for the individual cylinders developed in the correction
signal generator 110. The corrected signals thus obtained are
supplied to the pulse generators 108. Upon arrival there of trigger
pulses from the pulse generator 102, generators 108 form control
signals of substantially rectangular shape whose durations
represent the basic fuel charge signal on line 106, corrected for
the individual cylinders in adders 107. In this way the injection
valves 9 are actuated in the desired manner at the appropriate
times.
In FIG. 9 there is shown the signal line 18 which serves to actuate
the pressure regulator 3 according to the comparison above
described, made in comparator 105. Line 18 may be omitted if the
fuel pressure in the fuel line is kept constant.
FIGS. 10 and 11 show two possible embodiments of the correction
signal generator 110 of FIG. 9.
In FIG. 10, the signals from lines 112 to 114 are supplied to
control elements 120 and 121, preferably having the form of
integral controllers with large time constant. Control elements 120
and 121 deliver to the signal lines 109 for cylinders a and c
correction signals dependent on the instantaneous difference
between the signals dependent on the instantaneous difference
between the signals on lines 113 and 114 and on lines 112 and 114
respectively. The signal on line 13 to cylinder a is in this case
not corrected but is rather taken as a basis for comparison.
Cylinder a is in this case therefore a master cylinder.
In the embodiment of FIG. 11, the signals on lines 112 to 114 are
supplied to control elements 130, 131 and 132. Moreover these
signals are added together in an adding circuit 133 and are then
applied to a buffer amplifier 134. The buffer 134 has a
transmission (amplification) factor of one third. The output signal
of the buffer 134, representing a mean of the signals received by
it from lines 112 to 114, is applied as a set value signal to each
of the control elements 130 to 132. These control elements then
take the difference of the two input signals thereto and form an
output signal which is applied via signal lines 109 to the several
addition elements 107 in FIG. 9.
While the invention has been described hereinabove in terms of a
number of presently preferred embodiments of the apparatus thereof,
and in terms of the presently preferred practice of the method
thereof, the invention itself is not limited thereto, but rather
comprehends all modifications of and departures from the apparatus
and practice hereinabove described properly falling within the
spirit and scope of the appended claims.
* * * * *