Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
Device for the Preparation_of Liquid Fuels For
Mixture-Compressiny Internal Combustion Engines
The invention relates to a device for the
preparation of liquid fuels for mixture-compressing
internal combus-tion engines with carburators, by means of
which additional auxili.ary air flows in-to the suction
system downstream of the butterfly valve of the
carburator with the aid of slots disposed in the suction
canal as a function oF a control valve which depends on
the butterfly valve.
A device of -the above mentioned kind is known in
which auxiliary air is introduced into the suction system
downstream of the butterfly valve of the carburator by
means of slots disposed in the suction canal. ~lowever,
the air throughput through these slots is relatively
small, with the at-tendant disadvantage that relatively
high toxic NOx components are emitted virtually
throughout the entire speed range.
Therefore, the problem underlying the invention
is to propose a device of -the kind mentioned at the
outset which is characterized by low toxic gas emissions,
in particular toxic NOx gas emissions, over virtually
the entire speed range of the internal combustion engine.
To solve the problem posed, the invention uses
two slots opposite each
~
~2,~
other in the suction canal through which the auxiliary
air flows at very high veloci-ty already in the
transition, and in the partial load range at the speed of
sound and in that the two slots of circular segment shape
are precisely opposite each other. The projection of the
longitudinal axis of the butterfly valve shaft forms the
axis of symmetry between the slots, and the slots are
di.sposed downstream of the butterfly valve in the area of
maximum formation of condensate.
What is achieved by these measures is that the
control valve which regulates the auxiliary air opens
already at low speeds so that, starting at these low
speeds up to a predetermined speed in the medium speed
range, the throughput of air at the auxiliary air slot
increases steadily. Starting at this medium speed range,
the throughput of air at the auxiliary air slot increases
steadily. Starting at this medium speed, the throughput
of air at the auxiliary air slot remains virtually
constant. A very low toxic NOx component,
corresponding to only about 1/3 of the toxic NOx
component of the preknown device described, is achieved
thereby virtually over the entire speed range of an
internal combustion engine equipped with such a device.
It is important here that the geometric design of the
slots and their arrangement in the suction tube with
respect to the point of maximum condensate formation is
in combination with the auxiliary air fed in.
38~
Accordinyly, the basic idea behind the invention
is that virtually over the entire speed range a relatively
lean mixture is to be combusted. Due to -the excess of
air in this mixture, which can be in -the order of magni-
tude of about 20 percent, the mentioned and unexpectedly
great reduction of the toxic NO components is obtained
while the internal combustion engine can at the same time
work at wear-reducing, relatively low temperatures.
Due to the measures mentioned, all drops of the
mixture flowing into the device are vaporized into the
finest mis-t~ making it possible to operate the internal
combustion engine with the mentioned and relatively high
air excess. This also requires a very homogeneous mixture
of fuel and auxiliary air, which is achieved by the means
mentioned.
In the device according to the invention the
other toxic gas components are also very low.
Furthermore, the fuel consumption is also low
because, due to the operation with excess air, the fuel
used is combusted completely and, therefore, completely
utilized energywise. The device according to the inven-
tion can also be used in already existing internal com-
bustion engines equipped with carburators which feed in
combustion air in idle. This is due -to the fact that in
these so called circulating air carburators the mixture
is improved only in idle and not in the transi-tion and
partial load range, as is the case in the subject of the
invention.
The heart of the invention is, among other
things, that, starting at a certain opening of the
control valve, the slots act as measuring cross-section,
which means that the control valve itself no longer
limits the air throughput in the intake canal to the
slots, a function now assumed only by the slots. This
causes each slot to act as Laval nozzle in -the area of
maximum condensate formation. In the underpressure range
exceeding .6 ata, the air flowing in through the
respective slot or the gas flowing in there reaches the
speed of sound.
This means that, in idle and transition, the air
or gas flowing in through the slots enters at such a
velocity that it flows to the opposite wall and meets the
air or gas entering there, therefore covering almost the
entire area below the main butterfly valve. The fuel
condensate, creeping along the carburator wall at a spee~
of about 10 cm/sec, meets the air or gas entering in -the
area of the slots at high speed and is atomized there.
It is essential that the velocity at the slots is very
high or can reach the speed of sound. This causes a
strong condensate removing effect at the rest of the
circumference of the round slot which contains the two
mutually opposite slots after the two gas flows meet at
high flow velocity, effec-ting an atomization of
condensate and fuel drops.
9~
Instead of auxiliary air, a reformed gas
obtained from the exhaust gas by splitting Flows through
the slots can be used. This achieves a novel, not
self-suggesting effect which is described below in
greater detail.
The return oF normal motor exhaust gases already
lower the toxic NOx gas components. But this return
causes an increase in consumption of about 5 percent.
Accordingly, it is another object of the
invention to avoid an increase in consumption due to the
return of exhaust gases and, in addition, to expand the
ignition limit of the mixture so that a lean mixture
which so far was not ignitable, is made ignitable
according to the invention.
This problem is solved by the technical teachiny
mentioned at the outset, according to which a ref`ormed
gas obtained -From the exhaust gas by splitting is caused
to flow through the slots instead of auxiliary air. This
also lowers at the same time the -toxic NOx components
by another percentage.
According to an aspect of the invention, the
reformed gas is produced by the thermo catalytic
splitting of the exhaust gas.
L9~39
A red hot platinum wire, acts as catalyst, in hydrogen
and oxygen. The platinum wire can be hea-ted to the
required temperature by electrical energy. By generating
the catalyst temperature required to split the exhaust
gases by means of electric power, -the reformed gas
component can be adapted quickly, optimally and in
advantageous manner to the different operating conditions
of a vehicle engine.
To produce the reformed gas a thermal reactor is
used which, may be connected via a canal to the exhaust
gas elbow, the outlet of the reactor ending upstream in
the inlet part of the lower carburator part via a
reformed gas line.
The effect of the reformed gas used according to
the invention is -that the fuel consumption is lowered,
due to the low throttling losses of a heat control, by
heating the fuel/air mixture in the partial load range,
and to initiate reliable ignition and comple-te combustion
of the lean fuel/air mixture, due to the wide ignition
range of the hydrogen contained in the reformed gas.
When Flowing through the slots, the reformed gas
brings about a dynamic and thermal preparation of the
fuel condensate, associated with a homogenization of the
total mixture and, due to the hydrogen contained in it,
reliable ignition and complete combustion of a very lean
fuel/air mixture.
~2~
The subject of the present invention follows
not only from -the subject of the individual patent claims,
but also from the combina-tion of the individual patent
claims.
All data and features disclosed in the documents,
in particular the physical design depicted in -the drawings,
are claimed as essential to the invention to the extent
that they are, singly or in combination, novel vis-a-vis
the state of the art.
The invention is explained below in greater
detail by way of the drawings showing only one embodiment
example. Further features and advantages of the invention
essent.ial to it are evident from -the drawings and their
description.
Fig. l shows a section of the lower carburator part along
line I-I in Fig. 2,
Fig. 2 a longitudinal section of a carburator according to
the invention,
Fig. 3 shows schematically how the reformed gas is obtained
from the exhaust gas.
A gas such as air, exhaust gas or reformed gas
is supplied to a carburator (l) containing the butterfly
valve (2) into a lower part (3) through the intake part (4)
with the control valve (5) and through a -tube (6).
When the engine idles, the control valve (5) is
closed. It is rnechanically connected to the butterfly
valve (2) of the carburator (1) and opens when the
butterfly valve (2) is opened from the idling range to
partial load and full load.
This gas, entering through the opened control
valve (5) in arrow direction (22), is sucked in by the
engine and flows through the suction canal (7) and the
ring canal (8). In the area of canal (7) there is a
division of the gas flow, a part of which goes in arrow
direction (23) through the slot (9) into the suction pipe
of the engine, while the other gas flow enters the
suction system in arrow direction (24) with little time
delay through the opposite slot (10). In some cases, it
is possible to combine slots 9 and 10 in-to a round slot.
As is evident from the illustration in Fig. 1
with respect to the arrow directions (23, 24) shown
there, the two slots (9, 10) of circular segment shape
are arranged so as to be exactly opposite each other, the
projection of the longitudinal axis of the butterfly
valve shaft (21) forming the axis of symmetry between the
slots (9, lû), and -the slots (9, 10) being disposed
downstream of the butterfly valve (2) in the area of
miximum condensate formation (Figs. 1 and 2).
Accordingly, the slots (9, 10) are opposite each
other at the wall sides of the carburator (1) where, in
the partial load range, i.e. when the butterfly valve (2)
is slightly to three four-ths open, the largest,
crescent-shaped passages for the fuel/air mixture are
located. It
is also there khat the greatest amount of fuel condensate
forms on the carburatox wall.
To the right and left of the butterfly valve
shaft (21), when the butterfly valve (2) opens, there
form between it and the carburator wall (l) first small
and then becoming bigger and blgger crescent-shaped
openings through which the fuel/air mixture flows. Under
par-tial load these openings are small so that the mixture
must s~ueeze through near the carburator wall, causing a
part of the fuel contained in the mixture to condensate
on the carburator wall.
Since tlle openings Eorming at the ends of the
butterfly valve shaf-t (21) between the butterfly valve
and the carburator wall under partial load are very small,
very little mixture and, hence, fuel passes through them.
A condensate preparation there, such as a slot
all around, would only bring half the flow energy to the
proper and necessary points and minimize the preparation
effect in the lower partial load range (city traffic).
Therefore, the design of the slots (9, 10) and their geo-
metric arrangement on the carburator wall depending upon
the position of the butterfly valve shaft and upon the
maximum condensate formation are very important.
The cross-section of the slots is designed so
that, starting at a slow travel speed already, the control
valve (5) opens a larger passage, thus no longer acting
to restrict the cross-sectional area for the -throughput
of gas in -the intake part (4). Since the internal cross-
sectional area of the -tube (6), the canal (7) and the
ring canal (8) is larger than that of -the slots (9) and
(10), they act as measuring cross-sec-tions (i.e. as the
only limitation of the air throughput) starting at a
travel speed of 80 to 100 km/h, thereby generating gas
velocities of 100 m/sec and more.
A particularly good thermal efficiency of the
engine and a further improved reduction of fuel consumption
and a further lowering of the toxic gas emissions are
achieved by the additional arrangement according to Figs.
2 and 3 which show that, instead of feeding in auxiliary
air as is possible in Fig. 1, it is preferred to have a
reformed gas flow out of the slots (9, 10) through the
tube (6) and the in-take (4).
The engine (11) shown in Fig. 3 has an exhaust
gas elbow (12) which connects via a flange (13) to the
muffler in a manner not detailed. The exhaust gas (27)
flowing in the elbow (12) is split in -the area of flange
(13) in arrow direction (28), and a part of it flows there
into a canal (14). The canal (14) forms -the entrance to
a thermal-catalytic reactor (15) fastened to the flange (13).
Disposed in the reactor (15) is e.g. a heating
wire (16) which is supplied via lines (17) and (18) with
-- 10 --
electrical energy such as from the car battery. The dls-
charge end (19) of the reactor (15) is connected to the
tube (6) of -the lower carburator part (3) via a reformed
gas line (20). The reformed gas (29) flows through the
reformed gas line (20) in the arrow direction shown.
For better catalytic action for the purpose of
splitting water vapor in-to hydrogen and oxygen, the
interior of the reactor (15) may be provided with materials
li~e vanadium or panadium in addition to possible process
materials such as carbon, gasoline, natural gas, etc. The
same applies to the heating wire (16) which, however, is
best made of platinum wire. The supply of electrical
energy brings it to a temperature a-t which the split up
of the water vapor occurs.
The reformed gas or the auxiliary air flowing
into the canal (7) in arrow direction (22) causes at the
mutually opposite slots (9, 10) a s-trong condensate removing
action of the condénsa-te flow (3) creeping down the car-
burator wall, thereby atomizing it in arrow direction (25,
26) and lifting it off the carburator wall. This results
not only in a finest dynamic and thermal a-tomization of
the fuel and homogenization of the fuel/air mixture, but
also in good ignition of a mixture made very lean by the
introduction of the hydrogen component in the reformed
gas, the mixture being not capable of ignition without the
introduction of the reformed gas. Furthermore, the NO in
the exhaust gas are lowered due to the return of the un-
combustible nitrogen to the lower carburator part (3).
According to tests conducted with the addition
of hydrogen in the partial load range of the engine, only
1 kg hydrogen per 25 kg gasoline is needed to obtain very
low CO, HC and NO values. This amount can be split up
from about 1/4 of the water vapor component in the exhaust
gas.
It is advantageous to limit the exhaust gas
return through the slots (9, 10) so tha-t the hydrogen
requirement in the returned exhaust gas corresponds to an
amount originating at an outpu-t of 80 - 100 km/h.
Example: A modern middle class car requires
approximately 25 HP at 100 km/h. With the mixture pre-
paration according to the invention, -this requires
approximately 4 kg gasoline per hour. As to their -through-
put, the slots must be designed so that .04 kg hydrogen
in the returned exhaust gas finds passage through the
slots (9, 10). At higher loads the addition of hydrogen
to the gasoline decreases proportionately, at lighter
loads the amount is controlled by the control valve (5).
In the main travel speed range this results under partial
load in a high velocity of the returned gas through the
slots t9, 10) and, hence, in a good preparation of the
wall condensate in the carbura-tor (1) and an intimate,
homogeneous mixing of both gas flows. This is very
important so that a uniform fuel/air/gas mixture reaches
all cylinders.
