Note: Descriptions are shown in the official language in which they were submitted.
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A KGROUND OF THE INVENTION
1. Field o the invention
This invention relates to burner devices, and has
particular~ although not e~clusive relevance to burner
devices for use in vehicles, such as lorries.
2. Descri~tion o the prior art
Where it is necessary to incorporate a burner device in a
vehicle, for example as a cab heater, it is convenient
for the burner~ to be fuelled by fuel from the main uel
tank for the vehicle. This requries~ however, the use of
a flow modulator to control the flow of pressurised fuel
from the~tank to the burner device. Hitherto the flow
modulator has taken the form of a pump, having a variable
pumping rate. There are, however, difficulties with the
variable rate DC motors incorporated in such pumps.
SUMMARY OF THE INVENTION
:
It is an object of the present invention to provide a
- burner device suitable for use in a vehicle but wherein
the use of such complex flow modulators is avoided.
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According to the present invention there is provided a
burner device comprising: a fuel conduit having an inlet
into which fuel may be admitted, and an outlet by which
fuel may exit, an electromagnetic valve for regulating
the flow of fuel from the inlet to the outlet, means for
igniting the fuel exiting from the outlet, and means for
controlling the electromagnetic valve in dependence on
the required heating effect of the device.
The device suitably incorporates a means for introducing
combustion gas into the flow of fuel exiting from the
outlet. The combustion gas preferably is arranged also
to provide cooling of at least part of the conduit. The
device may incorporate a nozzle means co~municating with
the outlet, the means for introducing combuætion gas
being arranged to mix pressurised combustion gas with
fuel in the nozzle means such that the nozzle means is
effective to emit atomized fuel.
BRIEF DESCRIPTION OF THE DRAWINGS
Two embodiments of the invention will now be described,
by way of example only, with reference to the
accompanying drawings of which:-
Figure 1 shows a schematic longitudinal sectional view of
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part of the first embodiment, and
: Figure 2 shows a schematic longitudinal sectional view of
the second embodiment.
:~ : DESCRIPTION OF THE PREFERRED EMBODIMENTS
::
: ~ Referring firstly to Figure 1 the first embodiment to be
described includes a fuel injector, indicated generally
;
as 1, mounted in a combustion can 3. The combustion can
3 is also provided with a combustion air inlet 5 and an
ignitor 7, the ignitor being of conventional design, for
: example a hot wire glow plug. The fuel injector~ 1
includes a fuel inlet 9 in which is fitted a filter 11,
and :a fuel outlet 13, ~the lnlet and outlet belng
~:~ ; connected by a lonyitudinàl passage 15 formed within a
housing 17. The passage of fuel through the ~fuel
~ in~ector 1: is controlled by an electromagnetically
: controlled vaIve: comprising an electromagnet including a
:solenoid coil 19 supported on coil former 21. The coil
~:former 21 is located inside an annular~cavity 23 defined
~;b~y concentric parts 25 and 27 of the housing 17. Both
~ ;~parts 25 and 27 are made of a magnetizable material, thus
: providing a magnetic circuit round the solenoid coil 19.
;~The valve further includes a valve pl~ate 29, also made of
magnetizable material, which is urged by a coil spring 31
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into contact with a valve seat in the form of a disc 33in which is formed an aperture 35. The valve plate 29,
when in ~he position shown in Figure 1, thus blocks the
aperture 35 in the disc 33, thereby preventing the flow
of fuel from the fuel inlet 3 through the passage 15 to
the fuel outlet 13.
Upon energization of the solenoid coil 19, the valve
plate 29 is magnetically attacted towards the adjacent
end face of part 23 thus unblocking the aperture 35 in
disc 33. Fuel is then able to pass around the valve
plate 29 and through the aperture 35 to the fuel outlet
13. Upon de-energization of the solenoid coil 19 the
valve plate 29 is returned by the action of the spring 31
into contact with the disc 33 thereby blocking the flow
o fuel through the aperture 35.
Thus in use of the device the fuel inlet 9 is connected
to the fuel tank of a vehicle ~not shown)from which fuel
is supplied to the inlet 9 under pressure. On
energization of the solenoid coil 19 fuel, which may be
liquid or gaseous, passes through the injector 1 into the
chamber 3 where it is ignited by the ignitor 7.
Au~iliary combustion air, pressurised to typically 5 to
10 psi, is admitted via the inlet 5 into the chamber 3 to
aid air/fuel mixing and also to provide cooling of the
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injector during and after operation of the burner device.
Where the device is to be used as a heating device for
the cab of a truck there is also provided a temperature
sensing device, shown schematically as 36~ whose output
is an electrical signal corresponding to the sensed
temperature. Signals from the temperature sensing device
36 are used to control the electromagnetic valve so as to
regulate the time intervals during which the solenoid
coil 19 is energized and fuel can pass from the inlet to
the outlet of the injector 1. Means 36a are provided
such that the control signals are pulsed, the mark to
space ratio, the width of the signals, or the frequency
of the signals being variable so as to control the
temperature of the cab of the truck.
The device as thus described also finds application as a
burner for periodically burning off carbon formed on the
traps incorporated in the exhaust of a diesel vehicle to
trap the carbon particulates emitted due to the
combustion of diesel fuel during normal use of the diesel
vehicle. The operation of the device will however be
arranged to be initiated by, for example, a timing mean,
shown schematically in Figure 1 as 38, so as to cause
energization of the solenoid coil 19 and thus operation
of the burner at appropriate time intervals depending on
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the accumulation of particulates in the trap. The burner
device may also f ind application in an engine block
heater.
Referring now to Figure 2, the second embodiment to be
described is a modification of the first embodiment, and
thus corresponding features are correspondingly labelled
and will not be described in detail. The combustion air
inlet 5 formed in the combustion can 3 in the first
embodiment is, in this embodiment, replaced by an
adaptor 37 fitted to the housing 17 of the fuel injector
1 via an O-ring seal 39. An air inlet 41 is provided in
the adaptor 37, this communicating with an outlet nozzle
43 into which fuel passing from the outlet 13 of the
injector l passes. A source ~not shown) of pressurised
com~ustion gas is connected to the inlet 41, the outlet
nozzle thus being effective to supply an atomized spray
of fuel.
It will be appreciated that whilst a burner device in
accordance with the invention finds particular
application in a vehicle so as to use the fuel f rom the
fueltank vehicle, a burner system in accordance with the
invention is also applicable wherever it is necessary to
modulate the fuel flow to the device, for e~ample in an
industrial or home heating furnace.
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It will also be appreciated that as a burner device in
accordance with the invention is, effectively, a closed
loop system, the efficiency of the burner device will not
be dependent on the accuracy of the control of the flow
of fuel through the fuel conduit of the device. Thus it
is not necessary for the burner device to be constructed
to very close tolerances.
