Note: Descriptions are shown in the official language in which they were submitted.
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ENGI~E FUEL HEATING A~D OIL FI:LTRATION APPARATUS
The invention relates to apparatus for use in heating fuel prior
to its ignition in an engine, especially a Diesel engine or
compression engine, and to -the simultarleous filtration of the oil
used to lubricate the engine.
It is known to pre-hea-t Diesel fuel prior its ignition into order
to reduce fuel consumption. Known apparatus or methods used are
either unreliable or do not heat the fuel in a controlled way.
For example, the heating devices affect the performance of the
engine by starving it of fuel from time to time or they are so
inefficient that more than one heating means is required or they
are so uncontrolled that they cannot be used in hot climates. It
is one object of the invention to provide reliable and efficient
and controlled apparatus and method for the purpose specified.
Accordingly in one aspect the invention provides an engine fuel
heating apparatus comprising a container having an inlet for the
ingress of hot lubrication oil from the engine and an outlet for
the egress of oil back to the engine, heat exchanger means
located within the container and arranged, in use, to be
substantially immersed within the hot oil flowing between the
inlet and outlet of the container, the heat exchanger means
having an inlet for the ingress of fuel from a reservoir thereof
and an outlet for the egress of heated fuel to the engine, and
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being arranged to pass the fuel to the engine as demanded, a body
of filter material being located within the container and
arranged so that the oil flowing between the inlet and outlet
passes through the body of fil-ter material and is thereby
filtered free of contaminants.
Apparatus of the invention can be provided as a single unit
capable of simultaneously performing two different tasks.
In a more specific aspect, the invention provides a container
having a compartment, the compartment having an open top and a
closed floor, an oil filter element being contained within the
compartment, an inlet being present in the floor of the container
for the ingress of hot lubricating oil from an engine, an oil
outlet comprising a pipe extending from a hole in the floor of
the compartment to the outside of the container, elongate heat
exchanger means comprising a length of tubing coiled about the
compartment and including an inlet for the ingress of fuel from a
reservoir thereof, and an outlet for the egress of fuel to the
combustion chamber of the engine, the tubing being dimensioned so
as not to substantially restrict the flow of fuel to the engine,
whereby, in use, hot oil is passed into the inlet of the
container through the filter element in the compartment and out
through the oil outlet and fuel is passed along the heat
exchanger from the inlet to the engine and the flowing fuel is
continuously heated and the oil is continuously filtered.
Preferably the heat exchanger means comprises a coil or like
length of tube. The diameter of the tube is selected so that the
rate of flow of fuel -to the engine is in excess of any engine
demand requirements. The length of the tube is determined by the
intended level of heating of the fuel and related factors.
The filter material may be a Nylon gauze or paper or a mixture.
Preferably the filter material comprises a microporous sheet of
resin bonded cellulosic fibres derived from sulphated wood pulp;
more specifically the filter material is a pulped mixture of
sulphated hard wood and soft wood Krafts. The fibres are split
and then resin bonded to form sheets in which the majority of
fibres are oriented in one direction, the sheets are then dried
and creped. Preferably the sheet has pores of 5 to 100 microns
diameter.
The fuel and the oil may be arranged to flow in the same
direction or in opposite directions.
It is a surprising feature of the invention that because the
heating of the fuel is so efficient there is a serious risk that
the fuel will be heated to a temperature above that at which the
fuel will be harmed chemically, e.g. by degradation. According
to another feature of the invention thermostat control means are
present to reduce the temperature below a predetermined limit,
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typically about 45C in the case of Diesel fuel. Preferably such
means are arranged to add relatively cold fuel from the fuel tank
to the hot fuel in sufficient quantity to reduce the temperature
as required.
In a much preferred feature, the apparatus as defined further
includes thermostat means located in the main pipeline present
between the container and the engine where the fuel is consumed,
the thermostat including a temperature sensing device connected
to a piston which at rest obstructs an inlet from an auxiliary
pipeline connected to a supply of unheated fuel, the piston being
arranged to reciprocate between two longitudinally spaced apart
perforate walls through which fuel flows towards the engine, the
piston and the device being spring biased towards the forward
perforate wall proximate the engine, the thermostat being
arranged that when the device senses a temperature above a
predetermined limit, the piston is urged rearwardly to expose the
inlet and allow cooler fuel into the main pipeline thereby to mix
with the fuel therein and so lower the temperature thereof. The
piston means which obstructs the inlet from the auxiliary
pipeline is arranged so that it does not obstruct the flow of
fuel to the engine. For this purpose the piston has elongate
passageways therethrough.
In another aspect the invention provides a method of heating fuel
for an engine prior to passing the fuel into the engine,
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comprising passing the fuel from a reservolr thereof into an
inlet of a heat exchanger means, the hea-t exchanger means being
subs-tantially immersed within hot oil flowing from the engine and
through a container within which the heat exchanger means is
located, and passing the fuel thereby heated into the combustion
chamber of the engine.
Preferably the method includes the step of maintaining the
temperature below a predetermined value.
In order that the invention may be well understood, embodiments
thereof will now be described by way of example with reference to
the accompanying diagrammatic drawings in which;
Figure 1 is a vertical sectional view through one embodiment
of the invention;
Figure 2 is a cross sectional view along line A-A of Figure
l;
Figure 3 is a schematic diagram showing another embodiment
of the invention; and
Figure 4 is a longitudinal sectional view through the
thermostat of the embodiment shown in Figure 3.
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The same reference numerals are used to iclentify similar parts in
the different embodiments.
The apparatus shown in Figures 1 and 2 of the drawings comprises
an outermost generally cylindrical container or canister 1 having
a lid closure 2 which, as shown, may be sealed to the canister 1
by means of screw threads 3 or other sealing means. The interior
of the canister 1 defines a chamber 4. An inlet 5 is present
in the base of the canister 1 as shown and is arranged, in use,
to be connected to an outlet from the oil lubrication system of a
Diesel engine (not shown). A generally cylindrical compartment 6
is located centrally within the canister 1 and standing on a
pillar 17. The canister and compartment 6 may advantageously be
constructed of stainless steel sheet welded or otherwise joined
together. The compartment 6 is open at the top to define an
entrance 7 and contains as a close fit a body of filter material
8, e.g. of cellulosic fibres, paper or the like. A short length
of pipe 9 extends between a hole 10 in the floor 11 of the
compartment 6 and an oil outlet 12 in the floor of the canister.
A heat exchanger 13 having an inlet 14 connectable to a fuel
reservoir (not shown), and an outlet 15 connectable to the
combustion chambers of an associated engine (not shown), is
located within the chamber 4. The engine may be a Diesel engine
having a high fuel demand. As shown, the heat exchanger 13
comprises a length of tubing, e.g. of copper or like thermally
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conductive material slightly spaced from and coiled several times
about the compartrnent 6. The outlet 15 is diametrically opposite
and vertically above the inlet 14. The diameter of the tubing is
large enough not to affect the rate of flow of fuel to the engine
and the length is selected according to the level of heating
required.
In use, lubrication oil heated by passage through the engine
lubrication system is pumped under pressure or drawn under vacuum
from the engine through the inlet 5 to fill the chamber 4
sufficiently to immerse the heat exchanger 13 in the hot oil.
The oil flows continuously in the annular space 16 between the
walls of the compartment 6 and the canister 1, through the
entrance 7 of the compartment 6 and down through the body of
filter material 8, where particles of carbon or metal or water
and other harmful materials are removed. The filtered oil then
returns via the hole 10 in the floor 11 of the compartment 6 and
the pipe 9 to the engine. Meanwhile, fuel is pumped from the
reservoir and into the inlet 14 of the heat exchanger coil 13.
During passage through the heat exchanger 13, heat is transferred
from the hot flowing oil to the relatively cooler fuel. The fuel
then passes under pressure through the outlet 15 and into the
combustion chambers of the engine. It will be noted that the oil
flows vertically up into the chamber 4 and then down to the
outlet 12 through the filter whereas the fuel ~lows spirally in
heat exchanger coils 13. The two fluids thus flow in different
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directions, i.e. transversely, for efficien-t heat exchange. We
nave discovered that with oil sirculating at a temperature of
about 90C, it is possible to heat the fuel to a -temperature of
about 40-50C or more. At such a temperature useful reductions
in fuel consumption and other benefits can be achieved. Using
such a system, the fuel flow is not substan-tially restricted
thereby avoiding fuel starvation.
Periodically, the body of filter material will become clogged and
can be replaced by removing the closure 2 and substituting a new
fil'cer for the old filter in the compartment 6.
An adaptor may be present on the inlet to the heat exchanger to
adjust the flow rate for different engine sizes.
As shown in Figure 3, a thermostat T may be incorporated in
circuit with the apparatus. As shown the thermostat is located
at the outlet pipe 15 leading from the apparatus to the fuel
injectors of the engine. The thermostat T comprises a length of
piping 20 interposed in the main pipeline between the outlet 15
of the apparatus of Figures 1 and 2 and the fuel injectors, not
shown. At each end the length is connected by a nut 21 to the
adjacent threaded ends of the main pipeline 22. The pipe 20
contains a passageway 23. The length has an inlet port 24 in one
side wall connected to an auxiliary pipeline 25 to the main fuel
reservoir. The pipeline 25 will typically be much shorter than
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the length of the heat exchanger coil 13.
A piston 26 having elongate passageways 27 is present in the
passageway 23 which includes a forward shoulder 28 to limit its
forward travel. The piston 26 is urged forward by a spring 29
biased between a rearward per,orate wall 30 and the rearward face
31 of the piston 26. A forward perforate wall 32 is present in
the passageway 23 and has a central socket 33 to receive t'ne body
of a thermostat sensor 34. The sensor 34 has a rearwardly
extending push rod 35 opposite the forward face 36 of t'ne piston
26. 0 rings 37 are present a-t each end of the length. At rest,
the body of the sensor body 34 is in the socket 33 in the forward
perforate wall 32, with the piston 26 adjacent thereto and
obstructing the inlet port 24. Heated fuel flows forwardly
through the rearward perforate wall 30 through the passageways 27
of the piston 26 and through the holes of the forward perforate
wall 32 about the sensor body 34. When the temperature of the
heated fuel rises above a predetermined limit, say about 45C,
the sensor 34 is actuated and the push rod 35 urges the piston 26
rearwardly exposing the inlet 24 according to the distance
travelled by the piston 26. Unheated fuel can then flow
forwardly from the auxiliary pipeline 25 to join the heated fuel
disposed about the sensor 34, the two fuels being mixed on their
passage through the holes in the forward perforate wall 32. When
the temperature falls below the predetermined limit the sensor
retracts and the spring 29 urges the piston 26 forward to
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obstruct the port 24 again. The partC; may be dimensioned so that
the unheated fuel will be drawn through the pi2e 25, without
affecting the flow of the heated fuel.
The apparatus may be provided as a separate accessory, or, for
exarnple, the container 1 may be integrally cast into the engine
block. Two or more units may be linked together in series to
suit engines of larger si~es. The thermostat may be interposed
between the fuel outlet pipe and the fuel injectors as shown, or
it may be associated with the oil circuit. The apparatus may be
used with a petrol engine with appropriate modifications.
Because the fuel is preheated in a controlled way, i.e. to a
predetermined temperature range, the fuel is consumed efficiently
with much reduced pollution. In evaluations, we have been able
to show a saving in fuel cost of up to 15% and the following
reductions in exhaust emissions:
CO from 60 to 30 ppm and from 50 to 20 ppm
NOX from 10 to 4 ppm and from 12 to 5 ppm
HCHO down to 0.6 ppm
The oil filtration acts to remove all particles larger than 2
micron. Calculations have shown that the distance travelled
between oil changes can be extended to 100,000 km.
