U.S. patent application number 09/900665 was filed with the patent office on 2002-01-10 for internal combustion engine.
Invention is credited to Fahringer, Albert, Lutz, Bernd, Skorjanz, Peter.
Application Number | 20020002826 09/900665 |
Document ID | / |
Family ID | 3686406 |
Filed Date | 2002-01-10 |
United States Patent
Application |
20020002826 |
Kind Code |
A1 |
Fahringer, Albert ; et
al. |
January 10, 2002 |
Internal combustion engine
Abstract
An internal combustion engine, in particular a stationary gas
engine, comprising a compressor arranged in the induction tract, in
particular an exhaust gas turbocharger, an electrically operable
blow-off valve connected downstream of the compressor, and a
pressure sensor for detecting the pressure actual value of the
mixture in the region of the blow-off valve. In accordance with the
invention there is provided, a device (9) for detecting the engine
power output (N), a device (10) for calculating a pressure
reference value in dependence on the detected engine power output
and a relationship previously stored in a memory between engine
power output (N) and pressure reference value (P.sub.soil), and a
regulating device (11) for regulating the blow-off valve (7) until
the pressure actual value (P.sub.1st) reaches the calculated
pressure reference value (P.sub.soil).
Inventors: |
Fahringer, Albert; (Kossen,
AT) ; Lutz, Bernd; (Pflach, AT) ; Skorjanz,
Peter; (Paudorf, AT) |
Correspondence
Address: |
LORUSSO & LOUD
440 COMMERCIAL STREET
BOSTON
MA
02109
US
|
Family ID: |
3686406 |
Appl. No.: |
09/900665 |
Filed: |
July 6, 2001 |
Current U.S.
Class: |
60/602 |
Current CPC
Class: |
Y02T 10/144 20130101;
F02D 2200/0406 20130101; Y02T 10/12 20130101; F02D 23/02 20130101;
F02D 41/0007 20130101 |
Class at
Publication: |
60/602 |
International
Class: |
F02D 023/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 7, 2000 |
AT |
A 1163/2000 |
Claims
1. An internal combustion engine, in particular a stationary gas
engine, comprising a compressor arranged in the induction tract an
electrically operable blow-off valve connected downstream of the
compressor, and a pressure sensor for detecting the pressure actual
value of the mixture in the region of the blow-off valve,
characterised by a device (9) for detecting the engine power output
(N), a device (10) for calculating a pressure reference value in
dependence on the detected engine power output and a relationship
previously stored in a memory between engine power output (N) and
pressure reference value (P.sub.soil), and a regulating device (11)
for regulating the blow-off valve (7) until the pressure actual
value (P.sub.1st) reaches the calculated pressure reference value
(P.sub.soil).
2. An internal combustion engine as set forth in claim 1
characterised in that there is further provided a temperature
sensor (12) for detecting the mixture temperature (T) upstream of
the inlet valves, wherein the device (10) for calculating the
pressure reference value besides the engine power output (N) also
takes account of the detected mixture temperature (T) in accordance
with a previously stored relationship.
3. An internal combustion engine as set forth in claim 1
characterised in that the blow-off valve (7) is arranged between
the compressor (3) and a throttle valve (4) in the induction tract
(1).
4. An internal combustion engine as set forth in claim 1
characterised in that there is further provided a device (14) for
detecting the speed of rotation (n) of the engine (M), wherein a
comparison device (15) loses the blow-off valve (7) independently
of the signal from the regulating device (11) if the speed of
rotation (n) is or falls below a predeterminable reference value
(n.sub.min).
5. An internal combustion engine as set forth in claim 1
characterised in that the compressor is an exhaust gas
turbocharger.
Description
[0001] The invention concerns an internal combustion engine, in
particular a stationary gas engine, comprising a compressor
arranged in the induction tract, an electrically operable blow-off
valve connected downstream of the compressor, and a pressure sensor
for detecting the pressure actual value of the mixture in the
region of the blow-off valve.
[0002] In order to improve the load shut-down characteristics in
the case of engines, in particular gas engines, it is already known
for a blow-off valve to be connected downstream of the compressor
in order to be able to bring down the charging pressure in load
removal situations without turbocharger pumping. Turbocharger
pumping occurs whenever the compressor is `throttled` at a working
point with a great deal of throughput on the outlet side. That
procedure--once started--is totally uncontrollable and generally
results in `total loss` of the charging pressure with subsequent
stoppage of the engine. In order to prevent an excessive increase
in the engine speed in the event of load shutdown however,
`throttling` must be effected. Therefore, by means of blow-off
regulation, a valve downstream of the turbocharger is opened
virtually at the same moment in time and that therefore affords the
possibility of being able to reduce the throughput in a controlled
fashion (in spite of closure of the throttle valve) U.S. Pat. No.
5,526,645 discloses an excess air control system for a dual-fuel or
spark ignition gas internal combustion engine in which an air
blow-off valve is coupled to an air bypass-line linking the air
intake to a turbo charger and the air manifold in order to control
the air manifold pressure dependence on different measured engine
characterisation parameters. This concept cannot be used for
improving the load shut down characteristics of an internal
combustion engine of the kind set forth which is mainly controlled
by a throttle valve, because blowing an air-gas-mixture around a
turbo charger in a bypass-line results in a negative impact on the
air-gas-mixture and is therefore not practicable.
[0003] The object of the invention is to provide an internal
combustion engine of the kind set forth in the opening part of this
specification for reliable regulation for the blow-off valve, in
particular for the avoidance of turbocharger pumping.
[0004] The internal combustion engine according to the invention is
characterised by:
[0005] a device for detecting the engine power output,
[0006] a device for calculating a pressure reference value in
dependence on the detected engine power output and a relationship
previously stored in a memory between engine power output and
pressure reference value, and
[0007] a regulating device for regulating the blow-off valve until
the pressure actual value reaches the calculated pressure reference
value.
[0008] The invention is based on the notion that, at a given
combustion gas-air ratio of the mixture (and at a given
temperature) a predetermined relationship obtains between the
engine power output and the pressure of the mixture in the
induction tract. In accordance with the invention, that
relationship is utilised to afford a pressure controlled regulation
effect for the blow-off valve. The relationship between engine
power output and the pressure reference value can be ascertained
either empirically or from measurements. It can then be stored for
example in the form of a formula with given parameters or in the
form of a cross-reference table. At any event that arrangement is
capable of achieving a pressure reference value from the actually
measured engine power output and a correctively involved
temperature value.
[0009] The blow-off valve is now regulated until the pressure
actual value reaches the pressure reference value. In general, that
pressure reference value above which the blow-off valve opens is
set higher by a small amount (for example between 0.2 and 0.3 bar)
than corresponds to the empirical and measured relationship between
the values involved, in the case of an engine without blow-off
valve. That therefore advantageously provides With the blow-off
valve a safety margin in relation to the set pressure point, so
that a normal engine regulation system which acts on the throttle
valve still has an adequate effective range of influence. When the
throttle valve is completely open therefore the engine speed still
cannot be brought under control although a large part of the
`over-power` is removed by way of the blow-off valve. The actual
reduction in excessive speed of rotation then has to be effected by
way of the above-mentioned throttle valve control system. It will
be appreciated that the throttle valve does not now have to be
closed very far because of the pressure which has been kept at a
low level, in order to be able to reduce the engine power output
under the given load.
[0010] If the pressure downstream of the compressor which is in
particular an exhaust gas turbocharger falls below the reference
value the blow-off valve is closed, which means that as much mass
flow as possible again passes to the engine and also to the
turbine. As a result, the engine power output and also the
turbocharger speed can be held at a sufficiently high level so that
the engine speed does not fall excessively.
[0011] For shut-down procedures in the range of low levels of power
output, a minimum reference value is predetermined for the pressure
so that the valve does not remain constantly open in an overspeed
situation and when the pressure is already low. By virtue of the
regulating procedure, no compressor pumping occurs with a
sufficiently large blow-off valve cross-section and sufficiently
rapid opening of the valve, as the blow-off valve holds the
charging pressure at a low level in the ranges in which the
throttle valve can close far by virtue of the overspeed and in
which therefore there is a pumping risk.
[0012] Preferably therefore for that purpose there is further
provided a device for detecting the speed of the engine, wherein a
comparison device closes the blow-off valve independently of the
signal from the regulating device when the speed is or falls below
a predeterminable reference value The regulating system according
to the invention remains a pressure-controlled regulating system.
The speed signal is used independently of that pressure-controlled
regulation effect to close the blow-off valve when the speed falls
below a reference value.
[0013] Further advantages and details of the invention will be
described in greater detail with reference to the specific
description hereinafter.
[0014] The FIGURE shows an embodiment of an internal combustion
engine according to the invention.
[0015] The internal combustion engine M according to the invention,
in particular a multi-cylinder gas engine, has in its induction
tract 1 an air-gas mixer 2. The mixture is compressed by way of the
turbocharger and passes by way of the throttle valve 4 to the inlet
valves of the internal combustion engine M. A mixture cooler which
is possibly provided is not shown here.
[0016] The turbine 6 of the turbocharger is arranged in the exhaust
gas tract 5 of the engine M in per se known manner.
[0017] Disposed in the induction tract 1 of the internal combustion
engine M is an electrically operable blow-off valve 7, the
regulation of which is subject-matter of the present invention. The
blow-off valve can be actuated by way of a control line 8 in
respect of its degree of opening or closing.
[0018] In accordance with the invention there is now provided:
[0019] a device 9 for detecting the engine output power N,
[0020] a device 10 for calculating a pressure reference value
P.sub.soil in dependence on the detected engine power output N and
a relationship, stored previously in the memory, between the engine
power output N and the pressure reference value P.sub.soil, and
[0021] a regulating device 11 for regulating the blow-off valve 7
until the pressure actual value P.sub.1st (sensor 13) reaches the
calculated pressure reference value.
[0022] The previously stored relationship between the engine power
output and the pressure reference value is diagrammatically
represented in the Figure by a characteristic curve. That
characteristic curve can be ascertained empirically or by
measurements. It can be stored for example in the form of a formula
together with stored parameters or in the form of a cross-reference
table. As a correction value in relation to the relationship, it is
also possible to take account of the mixture temperature T which is
detected by way of a temperature sensor 12.
[0023] The illustrated device now operates as follows: the engine
power output N which is detected at the present time and the
mixture temperature T are fed to the device 10. The latter then
ascertains from a predetermined relationship a reference value for
the mixture pressure. By virtue of opening and closing of the
blow-off valve 7 the regulating device 11 then regulates to that
mixture pressure, in which case the pressure actual value is
detected in the region of the blow-off valve 7 by the pressure
sensor 13.
[0024] This therefore overall involves pressure-controlled
regulation of the blow-off valve.
[0025] In accordance with a particular embodiment of the invention
it is further provided that the speed of rotation n of the engine
is detected by way of a device 14. A comparison device 15 detects
that engine power output N and in any case closes the blow-off
valve 7 if the actual speed falls below the predetermined reference
speed n.sub.min. That occurs even if the pressure-controlled
regulation action by way of the regulating device 11 were to open
the blow-off valve.
* * * * *