Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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DIESEL ENGINE SECONDARY FUEL INJECTION ~YSTEM
FIELD OF THE INVENTION
This application pertains to a method of economically
operating a diesel engine by fueling the engine with a mixture
of diesel fuel and a secondary fuel such as propane, the relative
amounts of diesel and secondary fuels being controllably varied
as a function of various operating parameters.
BACKGROUND OF THE INVENTION
Diesel engine fuel systems which utilize diesel fuel
as the primary fuel and a secondary fuel such as propane are well
known. Conventionally, dual fuel systems of this sort are
employed to increase the horsepower output by the diesel engine.
As a general rule, it is undesirable to operate a diesel engine
in excess of the maximum ratsd horsepower specified by the engine
manufacturer, since this may cause damage to the engine and/or
void the manufa¢turer's warranty coverage for the engine. Dual
fuel ~ystems are nevertheless desirable in that the price of the
secondary fuel is typically less than the price of the primary
diesel fuel. If a diesel engine can be operated efficiently and
within the manufacturer's specifications with a dual fuel system,
then significant cost savings may be realized over extended
operating cycles when the combined cost of the primary and
secondary fuels are taken into account. ~he present invention
is directed to a method of economically operating a dual fuel
diesel engine in a manner which optimizes the engine's per-
formance by continually varying the relative amounts of primary
and secondary fuel injected into the engine, as a ~unction of one
or more performance parameters, whilst adhering to the manu-
facturer's specifications for operating the engine.
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SUMMARY OF THE INVENTION
In accordance with a basic, preferred embodiment, the
invention provides a method of operating a turbo-charged diesel
engine by controllably injecting pressurized diesel fuel into the
engine, monitoring the boost pressure output by the engine's
turbo-charger, and controllably injecting a secondary fuel such
as propane into the engine in an amount which varies as a
function of the monitored turbo-charger boost pressure.
Advantageously, a plurality of pressure sensors are
coupled to the engine's turbo-charger. The sensors output
electrical signals representative of the turbo-charger's boost
pressure. An equal plurality of normally closed valves are
coupled between the engine and a secondary fuel reservoir. The
valves are each openable in response to an applied signal. Each
sensor is adjusted to detect a selected turbo-charger boost
pressure within a pre-defined pressure range. Accordingly, each
sensor produces an output signal when the turbo-charger output
increases to that selected pressure. The plurality of sensors
together produce a plurality of output signals distributed within
the pre-defined pressure range. The output signals are applied
to corresponding ones of the valves, thus opening the valves in
sequence as the turbo-charger boost pressure increases, and
admitting a progressively increasing amount of the secondary fuel
to the engine.
In accordance with a second aspect, the invention
provides a method of operating a diesel engine by controllably
injecting pressurized diesel fuel into the engine, monitoring the
pressure of the liquid diesel fuel supplied to the fuel
injectors, and controllably injecting a secondary fuel such as
propane into the engine in an amount which varies as a function
of the monitored diesel fuel pressure.
The first and second aspects of the invention may be
combined by controllably injecting the secondary fuel into the
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engine in an amount which varies as a function of both the
monitored diesel fuel pressure and the monitored turbo-charger
boost pressure.
In accordance with a third aspect, the invention
provides a method of operating a diesel engine powered liquid
pump by controllably injecting pressurized diesel fuel into the
engine, monitoring the hydraulic pressure of the pumped liquid,
and controllably injecting a secondary fuel such as propane into
the engine in an amount which varies as a function of the
monitored hydraulic pressure.
In accordance with a fourth aspect, the invention
provides a method of operating a diesel engine powered electric
generator by controllably injecting pressurized diesel fuel into
the engine, monitoring the electric current output by the
generator, and controllably injecting a secondary fuel such as
propane into the engine in an amount which varies as a function
o~ the monitored current. If the diesel engine which powers the
electric generator is equipped with a turbo-charger, then the
secondary fuel may be injected into the engine in an amount which
varies as a function of both the current output by the generator
and the turbo-charger boost pressure.
In accordance with a fifth aspect, the invention
provides a method of operating a diesel engine powered gas
compressor by controllably injecting pressurized diesel fuel into
the engine, monitoring the pressure of the compressed gas output
by the compressor, and controllably injecting a secondary fuel
such as propane into the engine in an amount which varies as a
function of the monitored pressure.
In accordance with a sixth aspect, the invention
provides a method of operating a diesel engine having an air
intake manifold by controllably injecting pressurized diesel fuel
into the engine, monitoring the air pressure within the manifold,
and controllably injecting a secondary fuel such as propane into
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the engine in an amount which varies as a function of the
monitored air intake manifold pressure.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a block diagram of the basic components of
a diesel engine propane injection system according to the
invention.
Figure 2 is a pictorial illustration of a fuel nozzle
ring for injecting propane into the air intake of a diesel engine
turbo-charger.
DETAILED DESCRIPTION OF THE PREFERRED EMBODINENT
Figure 1 is a block diagram which illustrates the basic
components of a diesel engine propane injection system
constructed in accordance with the preferred embodiment of the
invention. A suitable secondary fuel such as compressed propane
which is stored in tank 1 and ls supplied~ through electric lock-
off device 2, vaporizer/regulator valve 3 and fuel line 4 to fuel
nozzle ring 15. Fuel nozzle ring 15 is mounted in air intake
pipe 11, which delivers air from the engine's air cleaner (not
shown) to turbo-charger 12 mounted on diesel engine 10. Nozzle
ring 15 incorporates a plurality of fuel nozzles 8 which regulate
the amount of propane injected into air intake pipe 11.
One or more normally closed solenoid actuated valves
9 are provided on fuel nozzle ring 15. Propane supplied via line
4 is distributed by flow divider 7 into a number of separate
lines, one coupled to each of valves 9. The outputs of each of
valves 9 are coupled to one or more of injector nozzles 8. The
number of valves required will vary from one application to
another, depending upon the amount of propane required for
injection into air intake pipe 11.
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The boost pressure output by turbo-charger 12 is
detected by each one of a plurality of normally open pressure
sensitive switches 5. Switches 5 are coupled to air crossover
13 via hose 14. Each of switches 5 is adjusted to detect a
selected turbo-charger boost pressure falling within a pre-
defi:ned turbo-charger boost pressure range. As the turbo-charger
boost pressure increases to the pressure which a particular one
of switches 5 has been adjusted to detect, that switch closes,
thereby producing an output signal which is conveyed to a
lo corresponding one of solenoid actuated valves 9 along one of
wires 6. It will thus be understood that, by adjusting each of
switches 5 to detect progressively increasing turbo-charger boost
pressures, the full complement of switches will together produce
a plurality of output signals distributed within the pre-defined
turbo-charger boost pressure range.
In operation, as the turbo-charger boost pressure
increases within the pre-defined range for which switches 5 have
been adjusted, the switches close in sequence, applying their
re~pective output signals to corresponding ones of valves 9.
Application of an output signal to one of valves 9 causes that
valve to open, thereby admitting propane to the nozzle(s) to
which that valve is coupled, causing propane to be injected into
air intake pipe 11 for delivery to engine 10. As the turbo-
charger boost pressure continues to increase, addi~ional switchesclose, producing further output signals which in turn open
additional valves, causing further propane to be injected into
air intake pipe 11 and engine 10. If the turbo-charger boost
pressure increases above the pressure detected by the switch
adjusted to the highest pressure setting, then all of switches
5 will be closed and all of valves 9 will be open, admitting the
maximum amount of propane into air intake pipe 11 and engine 10.
If the turbo-charger boost pressure decreases below the pressure
detected by the switch having the highest pressure setting, then
that switch will re-open and it will no longer supply an output
signal to one of valves 9. The valve to which that switch is
connected will accordingly close, decreasing the amount of
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propane injected into air intake pipe ll and engine lO. If the
turbo-charger boost pressure continues to decrease below the
pressure settings of the other switches, then those switches will
also re-open, causing their corresponding valYes to close and
further reducing the amount of propane injected into air intake
pipe ll and engine lO until no propane is injected into air
intake pipe ll. Propane injection via sequential opening and
closing of valves 9 assists in maintaining a proper air/fuel
mixture throughout the operating range of engine 10, which in
turn enhances fuel economy, engine efficiency and pollution
control.
Those skilled in the art will appreciate that although
the invention has been described in the context of a diesel
engine equipped with a turbo-charger, non turbo-charged engines
may also benefit from the invention. For example, instead of
using switches 5 to monitor the turbo-charger boost pressure, one
may instead couple switches 5 to the fuel galleries which supply
diesel fuel to the engine's fuel injectors so that the switches
e~fectively monitor the fuel pressure within the fuel gallery.
By adjusting the switches to close at selected pressures
distributed within a pre-defined fuel pressure range, one may
controllably inject propane into engine 10 in an amount which
varies as a function of the monitored diesel fuel pressure.
Similarly, the operation of a diesel engine may be controlled by
monitoring the air preRsure within the engine's air intake
manifold with a bank of switches like those described above in
relation to Figure 1. The output signals produced by the
switches can then be used to control the injection of propane
into the engine in an amount which varies as a function of the
monitored air intake manifold pressure.
Those skilled in the art will further appreciate that
additional control over the operating characteristics of the
engine may be attained by controlling propane injection as a
function of more than one operating parameter. For example, in
the case of a turbo-charged diesel engine, one may employ two
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separate banks of switches; the first bank being adapted to
monitor the boost pressure of the engine turbo-charger as
discllssed above in relation to Figure l; the second bank being
adapted to monitor the fuel pressure within the fuel injector
galleries as just described. Propane may then be controllably
injected into the engine in an amount which varies as a function
of both the monitored diesel fuel pressure and the monitored
turbo-charger boost pressure, by coupling one of the turbo-
charger boost switches and one of the fuel pressure sensors to
a single propane injector valve.
The invention may also be adapted to control the
operation of a variety of diesel engine powered devices for
maximum fuel economy. For example, to control the operation of
a diesel engine powered liquid pump, one may use a bank of
switches like those described above in relation to Figure 1 to
monitor the hydraulic pressure of the pumped liquid and control-
lably inject propane into the engine in an amount which varies
as a function of the monitored hydraulic pressure. Similarly,
in the case o~ a diesel engine powered electric generator, one
may employ a bank of switches to monitor the electric current
output by the generator and controllably inject propane into the
engine in an amount which varies as a function of the monitored
current. The operation of a diesel engine powered gas compressor
may be similarly controlled by monitoring the pressure of the
compressed gas and controllably injecting propane into the engine
in an amount which varies as a function of the monitored gas
pressure.
As will be apparent to those skilled in the art in the
light of the foregoing disclosure, many alterations and
modifications are possible in the practice of this invention
without departing from the spirit or scope thereof. Accordingly,
the scope of the invention is to be construed in accordance with
the substance defined by the following claims.
