Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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BACKGROUND OF THE INVENTION
The present invention relates to power plants which
employ compression-ignition engines, and more particularly
to improvements in supercharged diesel plants wherein the
admission of fuel to the cylinder or cylinders of the engine
is regulated or regulatable as a function of the rate of
admission of oxygen. Still more particularly, the invention
relates to improvements in supercharged diesel plants wherein
the minimum amounts of admitted air and fuel are designed
to satisfy the requirements of the engine while operating
solely by suction and wherein the rate of admission of fuel
can be varied as a function of changes in the quantity of
combustion air which is admitted to the cylirder or cylinders
by the supercharging blower.
It is already known to provide a supercharging
blower or other suitable means to compress combustion air
which is admitted to the head of a diesel engine. This is
accomplished by providing means for increasing the pressure
of air in the inlet channel so that the cylinders of the
diesel engine receive larger quantities of combustion air,
i.e., quantities exceeding those which are required when
the engine is operated in uncharged condition (suction
operation). Thus, when the head of the engine receives
compressed air, a larger quantity of oxygen is available for
combustion of fuel than in an engine of identical size which
operates without a supercharger (suction operation).
Consequently, a larger quantity of fuel can be injected
into the cylinders and the power output of the supercharged
engine is larger. The fuel injection pump is adjusted by
a suitable adjusting element, e.g., by a device whose
position varies as a function of changes of air pressure
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in the head of the diesel engine so that the rate of fuel
injection conforms to the quantity of air in the air admitting
channel. As a rule, the plant employs a transducer which
converts pressure signals into impulses capable of actuating
~he adjusting means for the fuel injection pump as a
function of changes of the pressure of air which is admitted
into the cylinders of the engine. The pump is adjusted by
a suitable connecting rod or the like so that the rate of fuel
injection conforms to the pressure of air in the head of the
diesel engine. It will be seen that the consumption of fuel
increases with increasing air pressure; however the maximum
power output of the engine is increased accordingly.
A drawback of the just described conventional
supercharged diesel plants is that the consumption of fuel
is relatively high at such times when the engine is not
required to operate at maximum power output.
OBJECTS AND SUMMARY OF THE INVENTION
An object of the invention is to provide a novel
and improved supercharged diesel plant wherein the rate of
fuel admission into the cylinder or cylinders of the diesel
engine can but need not always be varied as a function of
changes of the rate of admission of oxygen to the cylinder
or cylinders.
Another object of the invention is to provide a
supercharged diesel plant whose fuel requirements are lower,
at least under certain circumstances, than the fuel
requirements of heretofore known diesel plants having
engines of the same size.
A further object of the invention is to provide a
diesel plant wherein the consumption of fuel can be reduced,
either automatically or by hand, when the operating conditions
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render it possible to reduce the power output of the engine.
An additional object of the invention is to provide
a supercharged diesel power plant which can be used as a prime
mover in automotive vehicles (such as trucks) and which
enables an operator or an automatic monitoring system to
reduce the fuel requirements of the engine when the vehicle
travels on flat terrain.
Another object of the invention is to provide a
supercharged diesel plant with novel and improved means for
initiating or preventing adjustment of the fuel injecting
means as a function of the rate of admission of oxygen into
the cylinder or cylinders of the diesel engine.
A further object of the invention is to provide a
novel and improved shutoff valve between the interior of the
head of a diesel engine and the means which adjusts the fuel
injection pump of a supercharged diesel plant.
Another object of the invention is to provide novel
and improved means for actuating the just outlined valve.
One feature of the invention resides in the provision
of a supercharged diesel plant which comprises an engine with
one or more cylinders, a pump or analogous adjustable fuel
injection means connected with and arranged to admit to the
engine fuel at a variable rate, a blower or an analogous
source of supercharged air arranged to admit to the engine
compressed air which is mixed with fuel prior to combustion,
means for adjusting the injection means (e.g., a transducer
which can shift a rod in response to the application of
fluid pressure and which normally maintains the rod in a
predetermined starting position) including means for monitoring
the pressure of air which is supplied by the source and means
(e~g., the aforementioned rod) for actuating the injection
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means so that the rate of fuel admission is normally a function
of the rate of admission of compressed air to the engine, means
(e.g., a flexible hose) for applying to the adjusting means
air at a pressure matching or proportional to the pressure
of air which is admitted into the engine, and a valve or
analogous means for selectively deactivating (e.g., sealing)
the applying means so that the rate of admission of fuel
deviates or can deviate from the rate of admission of air into
the engine when the deactivating means is operative to prevent
the adjusting means from regulating the admission of fuel
in dependency on the pressure of air which is admitted to
the engine.
The adjusting means is preferably constructed and
assembled in such a way that it effects a reduction of the
rate of fuel admission into the engine to a predetermined
minimum value (sufficient for operation of the engine by
suction) in response to deactivation of the applying means.
This can be readily accomplished by equipping the adjusting
means with a spring or the like serving to bias the afore-
mentioned rod to the starting position in which the rate ofadmission of fuel to the engine is held to a minimum.
Another feature of the invention resides in the
provision of novel and improved deactivating means which can
be utilized in a supercharged diesel plant of the above
outlined character. The deactivating means preferably
constitutes a shutoff valve which connects the adjusting
means with the interior of the head of the engine (or
directly with the supercharger) in one position of its
valving element and which connects the pressure-responsive
part or parts of the adjusting means with the atmosphere in
another end position of the valving element so that the
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aforementioned spring or the like can maintain the rod in
the starting position in which the rate of fuel admission
is held to a minimum.
The novel features which are considered as
characteristic of the invention are set forth in particular
in the appended claims. The improved diesel plant itself,
however, both as to its construction and its mode of
operation, together with additional features and advantages
thereof, will be best understood upon perusal of the
following detailed description of certain specific
embodiments with reference to the accompanying drawing.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a diagrammatic view of a supercharged
diesel power plant which embodies the invention; and
FIG. 2 is an enlarged sectional view of a valve
in the power plant of FIG. 1.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring first to FIG. 1 there is shown a
supercharged diesel plant with a diesel engine 1 having a head
2 which can receive compressed air from a supercharging blower
or supercharger 3 driven by combustion products (Buchi system)
flowing through the conduit 8. The reference character 3a
denotes the conduit for admission of atmospheric air, and the
character 3b denotes a conduit which delivers supercharged
air to the head 2, i.e., the pressure in the interior of the
head 2 (which delivers compressed air to the cylinders of the
engine 1) exceeds atmospheric pressure when the head 2
receives compressed air from the supercharger 3. The cylinders
of the engine 1 receive fuel from an adjustable fuel injection
pump 4 which draws fuel from a tank 5 by way of a filter
6. A return conduit 7 connects the pump 4 directly with the
tank 5.
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The plant which is shown in FIG. 1 further comprises
a control unit including a compressed air pipe 10 which is
connected between a valve 9 on the head 2 and a transducer
(pump adjusting means) 11 having a reciprocable output element
~2 (e.g., a rod) which is coupled to and regulates the
operation of the fuel pump 4. The axial position of the rod
12 determines the rate at which the pump 4 admits or injects
fuel into the cylinders (it is assumed that the engine 1 has
four cylinders). The valve 9 can seal (deactivate) the pipe
10 from the head 2 whereby the rate at which the pump 4
admits fuel decreases. When the valve 9 seals the pipe
10 from the head 2, the pipe 10 is connected to the atmosphere,
i.e. it cannot apply to the transducer 11 air at a pressure
which is proportional to air pressure in the conduit 3b or
in the interior of the head 2. The pressure in the transducer
11 then drops and the quantity of fuel which is admitted
by the pump 4 is reduced accordingly. Consequently, the
power output of the engine 1 decreases. By appropriate
adjustment of the valve 9 while the engine 1 is in actual
operation, e.g., while a truck or another vehicle which is
driven by the engine 1 is in motion, one can simulate a
reduced fuel requirement, when the output power requirements
upon the engine 1 are lower, by the simple expedient of
adjusting the valve 9 so that the pressure in the pipe 10
indicates to the transducer 11 that the pump 4 should
reduce the quantity of injected fuel. In other words, the
valve 9 can be adjusted to set the transducer 11 in such a
way that the axial position of the rod 12 does not reflect
actual pressure of air in the head 2. This renders it
possible to conform the power output of the engine 1 to the
momentary power requirements and to achieve significant
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savings in fuel. More particularly, the consumption of
fuel is more economical. The valve 9 can be actuated by
hand or automatically, preferably by remote control, such
as by way of a Bowden wire (mechanically), by an electro-
magnet or the like.
When the pipe 10 is sealed from the head 2
(deactivation of pipe 10 by the valve 9) and is in
communication with the surrounding atmosphere, fuel which
is injected into the cylinders of the engine 1 is combusted
with a surplus of air because the rate of admission of fuel
into the cylinders of the engine 1 is not a function of the
rate of admission of oxygen into the cylinders (the rate of
admission of oxygen is higher because the supercharger 3
delivers compressed air via conduit 3b while the valve 9
seals the pipe 10 from the interior of the head 2). This
contributes to more economical utilization of fuel and
contributes, quite significantly, to a reduction of the
percentage of smoke in combustion products.
FIG. 2 illustrates a presently preferred embodiment
of the valve 9. This valve comprises a valve body or housing
having a main portion 14 which is an elongated tubular member
having a first axial end with external threads 15 mating
with internal threads 16 in a bore of the head 2. The
valve body further includes a sleeve-like second portion 17
having external threads in mesh with the internal threads 18
at the other axial end of the main portion 14. The main
portion 14 defines a channel or passage 19 which communicates
with the interior of the head 2. The inner end portion of
the channel 19 is adjacent to a conical first valve seat
20 which is defined by the main portion 14 and faces a
spaced-apart second valve seat 21 which is provided at the
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inner end of the sleeve-like second portion 17. The main
portion 14 has at least one radial bore or port 22 which
is disposed between the seats 20 and 21 and extends through
a nipple 23 for the respective end portion of the pipe 10.
The latter may constitute aflexible hose which is adequately
secured to the main portion 14 of the valve body.
The valving element 24 of the valve 9 is
reciprocable in the main portion 14 between the seats 20 and
21 to seal the pipe 10 from the interior of the head 2
(i.e., to deactivate the means for applying fluid pressure
to the transducer 11) when it engages the seat 20 and to
seal the pipe 10 from the surrounding atmosphere when it
engages the seat 21. The valving element 24 has a conical
underside which is complementary to the seat 20 and a
radially extending shoulder which is complementary to the
seat 21. The pipe 10 communicates with the atmosphere via
channel or passage 25 in the sleeve-like portion 17 and a
venting port 31 in a cylindrical extension or dome 28 of
the valve 9. The port or ports 22 are never sealed, i.e.,
such port or ports communicate with the channel 19 or
with the channel 25, depending on the selected end position
of the valving element 24.
The shank 26 of the valving element 24 extends with
clearance through the passage or channel 25 and its upper end
portion 27 constitutes a rigid plunger which is reciprocable
in a cylinder chamber 29 defined by the dome 28. The
chamber 29 can receive compressed fluid (e.g., air) via
conduit 13 to move the plunger 27 downwardly against the
opposition of a valve spring 30 which surrounds the shank
26, reacts against the sleeve-like portion 17 and bears
against the underside of the plunger 27.
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When the valving element 24 assumes the lower end
position which is shown in FIG. 2, i.e., when it engages the
seat 20 and seals the interior of the head 2 from the pipe
10, the latter communicates with the atmosphere via port 31,
channel 25 and port or ports 22. The fuel injection pump 4
then delivers minimal quantities of atomized fuel into the
cylinders of the engine 1 because the position of the rod
12 simulates the minimum pressure of air in the interior of
the head 2 even though the pressure in the head 2 is or may
be high, i.e., even though the conduit 3b delivers supercharged
air at elevated pressure. At any rate, the pressure which
is represented by the axial position of the rod 12 does not
denote or is not indicative of the pressure which prevails
in the interior of the head 2.
If the pressure of fluid in the chamber 2~ is
reduced, the spring 30 expands and moves the plunger 27
upwardly whereby the shank 26 entrains the valving element
24 to the upper end position in which the latter engages the
seat 21 to seal the port 31 from the port or ports 22. At
the same time, the pressure in the pipe 10 matches that in
the interior of the head 2 so that the axial position of the
rod 12 (whose axial position is changed by the pressure-
responsive transducer 11) is indicative of actual pressure
in the interior of the head 2. The rate at which the
pump 4 then injects fuel into the cylinders of the diesel
engine 1 is a function of air pressure in the interior of the
head 2, i.e., a function of the quantity of combustion air
which is available for introduction into the cylinders of
the engine 1.
The rigid plunger 27 can be replaced with a flexible
plunger, e.g., a membrane whose marginal portion is fixedly
secured to the extension 28.
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If the engine 1 drives a vehicle, such as a truck,
the driver of the vehicle can change the position of the
valving element 24 by remote control (i.e., by changing
the pressure of fluid in the chamber 29) in dependency on the
desired power output of the engine. For example, the
conduit 13 can contain an electropneumatic valve 113 (shown
schematically in FIG. 1) which can connect the chamber 29
with a source 213 of pressurized gaseous fluid for displacement
of the plunger 27 when the need arises. It is equally possible
to employ an automatic regulator for the valve 113, i.e., to
provide actuating means for changing the position of the
valving element 24 as a function of one or more parameters,
such as the useful load that is carried by the vehicle, the
temperature of the surrounding atmosphere, the temperature
of combustion products, and/or others. The (automatic or
manually operated) regulator for the valve 113 is indicated
at 313.
In the illustrated embodiment, the valve 9 is
mounted on the head 2 of the engine 1. However, it is clear
that this valve can be installed in an intermediate portion
of the pipe 10 or directly on the transducer 11. In fact,
the valve 9 may constitute an integral component part of the
transducer 11.
The components 1, 2, 3, 4, 6, 8, 10, 11 and 12
are or may be commercially available parts of known diesel
plants, e.g., of plants known as V8-Diesellademotor Typ 815
manufactured by the firm Stayer, Daimler, Puch AG, Austria.
An important advantage of the improved diesel
plant is that the transducer 11 for the fuel injection pump 4
can be rendered operative or deactivated so that the rate
of fuel admission may but need not be a function of the rate
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of admission of oxygen into the cylinder or cylinders of the
engine. When the valve 9 connects the pipe 10 with the
surrounding atmosphere (i.e., when the valving element 24
engages the seat 20 as shown in FIG. 2), the rate of fuel
admission matches the minimum rate, i.e., the rate which is
normally selected only when the rate of oxygen admission into
the cylinder or cylinders is also reduced to a minimum value,
in spite of the fact that, at the very same time, the rate
of oxygen admission is or can be much higher than the
minimum rate. ~n the other hand, when the valve 9 permits the
conduit 10 to communicate with the interior of the head 2,
the operation of the fuel injection pump 4 is as expected,
i.e., the rate of fuel admission will be a function of the
rate of admission of oxygen into the cylinder or cylinders
of the engine 1.
If the pressure in the head 2 decreases while
the valving element 24 engages the seat 21, the pressure
in the pipe 10 drops and the transducer 11 adjusts the pump
4 accordingly, i.e., the rate of fuel admission is reduced
to a value matching that when the valving element 24 assumes
the end position of FIG. 2. At such time, the rate of fuel
admission is just sufficient to ensure satisfactory suction
operation of the engine 1, i.e., an operation in the course
of which air is merely drawn into the head 2 without any
supercharging by the device 3. The fuel consumption of the
plant is then reduced and the power output of the engine is
reduced accordingly.
When the valve 9 permits the pipe 10 to communicate
with the interior of the head 2, the pressure of air in the
interior of the head is normally higher than atmospheric
pressure because the s~charger 3 is on. ~he transducer 11
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monitors the pressure in the pipe 10 and adjusts the pump 4
(via rod 12) accordingly so that the quantity of fuel which
is admitted during each cycle is in proper relation to the
quantity of admitted oxygen. As stated above, the generation
of smoke is reduced in response to sealing of the pipe 10
from the interior of the head 2 when the supercharger 3 is
on (i.e., when the pressure in the interior of the head is
relatively high) because the quantity of oxygen in the
cylinders of the engine 1 then exceeds the minimum quantity
which is needed for adequate combustion of injected fuel,
i.e., the combustion of fuel is complete and the development
of smoke in the combustion products which flow in the conduit
8 is reduced.
Without further analysis, the foregoing will so fully
reveal the gist of the present invention that others can, by
applying current knowledge, readily adapt it for various
applications without omitting features that, from the
standpoint of prior art, fairly constitute essential
characteristics of the generic and specific aspects of my
contribution to the art and, therefore, such adaptations
should and are intended to be comprehended within the
meaning and range of equivalence of the appended claims.
