Note: Descriptions are shown in the official language in which they were submitted.
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Intake System for Internal Combustion Engine
The invention relates to an intake system for an internal combustion engine
according to the
preamble of claim 1.
It is know that in internal combustion engines with two inlet valves per
cylinder, a separate inlet
channel is provided for each inlet valve. To generate a high admission rate a
low load and/or low
rpm with a corresponding charge movment (swirl) in the cylinder, it is known
that one of the inlet
channels can be closed as a function of the operating point. One such
arrangement is described in
MTZ, 1994, vol. 9, page 519. With this known arrangement, two different inlet
channels primary
and secondary channels are provided per cylinder, one of which can be closed
by means of a valve
which is opened only when the engine reaches certain operating states. Altough
a better torque is
achieved in the lower rpm range and an improvement in combustion at underload
is achieved, this
arrangement is associated with a greater flow resistance, and furthermore, the
division into a
primary channel (small diameter, large length) and a secondary channel ( large
diameter, shorter
length) yields filling losses in the middle and upper rpm and load ranges due
to the geometry of
the primary channel.
German Patent DE 3, S 18 , 684 A 1 discloses an intake tube for a
multicylinder combustion engine
which has only one inlet valve per cylinder. The intake channels leading to
the inlet valves each
have a wall section which is designed to be at least partially elastically
adjustable. This achieves
the result that the velocity of flow prevailing in the intake tubes can be
adapted to the operating
parameters of the combustion engine.
German Patent DE 4,412,281 A1 discloses an inlet channel system for a
combustion engine with
several inlet channels per cylinder, with one inlet valve working in each. In
one of the inlet
channels is arranged a rotary slide valve by means of which the gas flow can
be throttled and
deflected. Consequently, it should be possible to adapt the charge movement in
the cylinder to the
operating parameters of the combustion engine.
An intake system in accordance with the characterising portion of the enclosed
Claim 1 is known
from DE 40 17 066 A 1, whereby a butterfly valve operates in one of two inlet
channels belonging
to a cylinder and only outer inlet channel of the inlet channels provided with
the partition is clear
when this butterfly valve is in closed state. At partial load, the valve is
brought into this position,
in which a swirling inflow into the combustion chamber is achieved. At full
load the valve is
completely open, as a result of which the cross-sections of both inlet
channels are fully utilised and
no swirling takes place. A characteristic of this configuration is that when
the butterfly valve is not
fully open it produces a substantial flow from the intake channel into the
inlet ducts, which are
very short because they are installed within the cylinder head, and this
results in swirling and has
an unfavourable effect on flow resistance. There is no provision for the
intake tube located in the
intake channel to be employed to balance the oscillation processes.
The present invention is based on the task of creating an intake system for a
reciprocating piston
internal combustion engine incorporating several inlet valves per cylinder
which, in addition to
enabling high torque at low speeds and optimum charging motion in the cylinder
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at partial load, also permits a high level of volumetric efficiency at full
load, by means of
oscillation balancing.
The objekt is achieved with an intake system according to claim 1. According
to this invention, the
intake channel leading to a cylinder of an internal combustion engine can be
modified so that ,
depending on the operating state of the combustion engine, forming a flow path
with a reduced
cross section, only one inlet duct is released, so that high flow velocities
are achieved at a low rpm
or at underload . Due to the asymmetrical intake through one inlet valve (in a
multivalve engine) ,
a swirl flow also develops in the cylinder, permitting a high exhaust gas
recycling tolerability and
a good lean running capability. The parition may assume any position between
minimal and
maximum cross section and thus can also determine the size of the amplitude of
the reduced
pressure wave in the intake channel which has a great influence on the
resonance in. the resonant
spaces upstream of the intake channel. At full load the combustion engine or a
high rpm, the
partition of the intake channel may be moved into a position in which all the
inlet ducts are
released, forming a flow path with the maximum cross section, i. e., maximum
filling and
maximum torque are achieved.
By throttling the intake mixture in an admission port on a mufti-valve engine,
the charging motion
and the turbulence swirl can be controlled so as to achieve the necessary
charging motion with the
lowest possible flow losses in every operational state.
The subclaims are based on advantageous embodiments and refinements of the
intake system
according to this invention.
This invention is explained below on the basis of schematic diagrams as
examples and with
additional details.
They show:
Figure 1: a schematic top view of an intake system according to this
invention;
Figure 2: a cross section along line II-II throught an intake channel from
Figure 1;
Figure 3: a view similar to that in Figure 1 with a maximum cross section of
the
intake channel;
Figure 4: a schematic view of a pneumatic system for adjusting the cross
section of the intake channel;
Figure 5: a block diagram of the entire intake system according to this
invention;
Figure 6: a top view of an intake system modified in comparison with Figure 1;
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Figure 7: a top view of another intake system modified in compassion with
Figure 1;
According to Figure 1, a combustion engine working with reciprocating pistons
in the example
shown here has six cylinders 4, each of which has two exhaust valves 6 and two
inlet valves 8 and
9 . Within the cylinder head, an inlet duct 10 or 11 runs to each inlet valve
8 or 9.
The two inlet ducts 10 and 11 provided for each cylinder 4 open into one
intake channels 13 which
connects them with an essentially know resonance chamber 15 of an intake
device 17.
In each of the intake channels 13, a movable partition 17 (shown with dotted
lines in Figure 1 ) is
provided along its length and is movable in the direction of double arrow 19
so that the inlet
channel 11 provided for the inlet valve 9 is optionally either closed or open.
Therefore, on its end
belonging to inlet duct 11 and preferably also on ist end belonging to the
resonance chamber 15 ,
partition 17 has a closing face which closes or releases the corresponding
opening cross sections.
If the partition 17 is in the position indicated with dotted lines in Figure
1, only the inlet duct 10 is
released and intake channel 13 has a cross section corresponding approximately
to half its
maximum value. If partition 17 according to Figure 1 is moved completely to
the right, intake
channel 13 has a maximum cross section and completely releases inlet duct 11.
A valve 19 is provided in resonance chamber 15, dividing resonance chamber 15
into two
individual chambers 21 and 23. An intake tube 25 and 27 leads from each
chamber 21 and 23 to a
throttle valve part in which is arranged a throttle valve 29 to control the
power of the combustion
engine.
Figure 2 shows the design of intake channel 13 in greater detail. Intake
channel 13 comprises a
rigid part 31, which is shown with an overall U-shaped cross section, and its
legs 33 and 35
accommodate a slide valve 37 which also has a U-shaped cross section and its
base forms the
movable partition 17.
On the free ends, slide valve 37 has flanges 39 and 41 that face upward and
together with
correspondingly designed parts of a housing 47, which is rigidly connected to
part 31, it forms
piston-cylinder units 49 to 51, whose interiors undergo changes in volume due
to displacement of
slide valve 37 relative to part 31 or housing 47. It is self evident that
suitable seals are provided
between flanges 39 and 41 or slide valve 37 and the rigit parts.
Along the length of flange 39 or 41, one or more bushings 43 and 45 are
provided, which serve to
hold helical compression springs 53 which push the slide valve 37 according to
Figure 2 toward
the right.
For better guidance of slide valve 37, housing 47 has a projecting half dog 57
which projects into
slide valve 37.
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In the position of slide valve 37 shown in Figure 2, intake channel 13 has a
minimum cross section
Q1, whereas in the position according to Figure 3 the cross section Q2 of
intake channel 13 is at its
maximum. Slide valve 37 is adjusted by a more or less strong vacuum acting on
the interior of the
piston-cylinder units 49 and S 1 through vacuum lines 55. If there is no
vacuum, slide valve 37 is
moved by helical springs 53 into the position according to Figure 3. At the
maximum vacuum, the
force of the helical springs S3 is overcome, and slide valve 37 is moved into
its position according
to Figure 2.
Housing 47 is provided with vent holes 59 for equalization of pressure.
It is self evident that slide valve 37 is provided with closing faces at the
top and bottom of its end
faces (according to Figure 1 ) to close the respective cross sections of the
inlet duct 11 or the
connecting openings of resonance chamber 15.
Figure 4 shows the device for controlling the vacuum lines 55:
A vacuum storage device 59 is connected by a return valve 60 to the resonance
chamber 15 which
is arranged downstream of throttle valve 29 and is under a reduced pressure at
underload. Vacuum
storage device 59 is connected to a distributor chamber 64, with the vacuum
lines 55 leading away
from it, by way of a 3/2-way electromagnetic valve 63 controlled by an
electronic controller 61.
For the case when an inadequate vacuum is available in vacuum storage device
59, a vacuum
pump 66 is provided and is switched on by a pressure manometer 68.
The design of controller 61 is shown in the schematic diagram in Figure 5.
Controller 61 contains
a microprocessor 70 and an input module 72 for microprocessor 70. The input
parameters are
preferably the engine rpm 80, the setting 81 of the throttle valve 29, the air
temperature 82, the
operating temperature 83 of the combustion engine, e.g., the water temperature
or the oil
temperature, the output signal of a knock sensor 84 and the position 85 of the
movable partition 17
as well as optionally additional operating parameters. From these input
parameters,
microprocessor 70 computes the optimum position of partition 17, which was
previously entered
into the microprocessor in the form of an engine characteristics map based on
empirical tests.
Another output of controller 61 controls the position of the movable valve 19
within the resonance
chamber 15.
The arrangement described her functions as follows:
In a lower rpm range or at a lower underload (throttle valve 29 mostly
closed), a maximum
vacuum acts on distributor chamber 64, which is driven by controller 61 by way
of the 3/2-way
valve 63, so that partition 17 is in the position according to Figure 2, i.
e., the cross section of the
intake channels 13 is minimal. In addition, valve 19 is closed. Due to the
reduction in intake cross
section in the lower rpm range, the velocity of flow prevailing there is
increased, so that an intense
charge movement prevails in the cylinders, offering good prerequisites for
thermodynamic
combustion. The swirl flow prevailing in the combustion chamber also permits
good lean running
capability and high exhaust gas recycling levels.
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WO 97I08434 PCT/EP 96I03586
In the lower to middle rpm range, the position of valve 19 remains largely the
same, although
throttle valve 29 is partially opened, which leads to a resonance in chamber
15 and increases the
charging efficiency and the torque of the combustion engine.
With increasing opening of the throttle valve and increasing rpm of the
combustion engine,
partition 17 moves into the position according to Figure 3 with diminishing
vacuum under the
influence of the force of helical springs 53. Maximum flow cross sections are
achieved, utilizing
all inlet valves, i. e. , optimum filling and torque are achieved. Thus, while
all inlet valves are fully
operative at a high rpm in the full load range, only one inlet valve is
operative in the underload
range, which permits the charge movement in the combustion space .
The embodiment shown in Figure 6 differs from that shown in Figure 1 in that
another valve 87 is
arranged between the two intake tubes 25 and 27, providing additional support
for the resonance
characteristic.
In the lower rpm range, both valves 19 and 87 are closed. In the middle rpm
range, valve 19
remains closed and valve 87 is opened. In the upper rpm range,both valves 19
and 87 are opened.
The position of the movable partition 17, like that of valves 19 and 87, is
controlled by controller
61.
Figure 7 shows another use of variable intake tubes 13 on the example of a
four-cylinder series
motor. To better adapt the vibration characteristic or the resonance
characteristic of the intake
system to the operating parameters of the combustion engine, individual
volumes V2 and V3 are
connected to the volume of resonance chamber 15 by means of valves 88 and 89
in the manner of
a Hemholtzresonator Valves 88 and 89 are controlled by control unit 61. At a
low rpm, valves 88
and 89 remain open, and with an increase in rpm, valve 89 is closed and then
88 is closed.
It is self evident that numerous modifications of the embodiment of the
invention described here
are possible:
For examble, the displacement of slide valve 37 may be controlled by an
electric motor, a
hydraulic mechanism or by other drive mechanisms.
The cross section of the intake channel can also be varied by a movable wall
in it which is
inherently flexible and is filled with a fluid as a function of operating
point, for example, where
parts that are mounted on it and are provided with a closing face increasingly
close the inlet ducts
or outlet openings of the resonance chamber.
