Invention is based on a method and an apparatus for
Operation of an internal combustion engine according to the type of the independent claims.
Improve the response of internal combustion engines
Turbocharger for several years, especially with variable turbine geometry
used. Nevertheless, modern engines have a so-called turbo lag
on. When accelerating, this results from low engine speed or
low engine load, where a desired torque only after
can be provided by the turbocharger for a few seconds. In addition, at
low mass throughput due to the motor even in stationary operation
the internal combustion engine the maximum torque by the maximum achievable
Turbocharger boost pressure limited.
is also known with the help of a, for example electrically
driven, auxiliary compressor or auxiliary loader at low
Engine air mass flows
pre-compress the intake air. This means a higher boost pressure,
a larger engine air mass flow,
a larger injection quantity
and therefore a greater torque
realizable. This can change the dynamic behavior of the internal combustion engine
can be improved and there can be a higher stationary maximum torque
can be achieved.
Advantages of the invention
and the device according to the invention
for operating an internal combustion engine with the features of the independent claims
the advantage that the auxiliary loader depends on a speed and
a load of the internal combustion engine is controlled. In this way
will it be possible
the auxiliary loader only when needed, for example to achieve it
a correspondingly large one
to activate predetermined torque of the internal combustion engine.
In this way, energy can be saved and an unnecessary nuisance
by the noise level
be avoided when operating the auxiliary loader.
those in the subclaims
are advantageous developments and improvements of the main claim
specified procedure possible.
It is advantageous if the auxiliary loader is above a predetermined one
Engine speed is turned off. In this way
becomes an unnecessary one
Operation of the auxiliary loader avoided, as at engine speeds above
the specified speed no turbo lag occurs, and an operation
at too big
Mass flow rates
Another advantage arises when the auxiliary loader is under a load
is switched off below a predetermined load value. Also
this way becomes an unnecessary one
Operation of the auxiliary loader avoided, since corresponding to the implementation
lower loads an additional
Compression of the air supplied to the internal combustion engine is not necessary
Another advantage arises when comparing the load with the
predetermined load value a positive temporal gradient of the load
taken into account in this way
will be in the form of an additional offset
load in the comparison. In this way, the auxiliary loader
also activated for loads below the specified load value
to ensure a correspondingly dynamic operation of the internal combustion engine
there is a further advantage if the specified load depends on
the speed of the internal combustion engine is determined. That way
the specified load, for example to implement a smoke limit
be used in diesel engines, so that an activation of the
Auxiliary loader for
the case is provided in which the smoke limit is to be exceeded.
there is a further advantage if the auxiliary charger is switched off with active exhaust gas recirculation.
In this way, the boost pressure can be prevented from being greater than
the exhaust back pressure becomes. The function of exhaust gas recirculation is
therefore not affected.
Another advantage arises when the auxiliary loader is activated
is realized by specifying a speed and the speed of the
Auxiliary loader depending
the speed and the load of the internal combustion engine is specified.
every engine speed and load in the range,
a suitable speed in which the auxiliary loader is to be activated
the auxiliary loader.
An embodiment of the invention is shown in the drawing and explained in more detail in the following description. Show it 1 a block diagram of an internal combustion engine and 2 a functional diagram to illustrate the inventive method and the inventive device.
of the embodiment
In 1 features 1 an internal combustion engine, for example a vehicle. The internal combustion engine 1 includes an internal combustion engine 40 , which is designed as a diesel engine in this example. The diesel engine 40 is via an air supply 25 Fresh air supplied. In the air supply 25 is an auxiliary loader 10 arranged. The auxiliary loader 10 is, for example, from one in 1 Electric motor, not shown, driven. This electric motor drives a compressor of the auxiliary charger 10 at a certain speed. The control of the auxiliary loader 10 Motor control is used to set the desired compressor speed 20 , The auxiliary loader 10 in the direction of flow of the fresh air supplied, which in 1 is represented by an arrow, arranged below is a main loader 5 , which can be designed, for example, as a compressor of an exhaust gas turbocharger. The auxiliary loader 10 in the direction of flow is in the air supply 25 an air mass meter 30 , for example a hot film air mass meter. The air mass meter 30 measures that of the internal combustion engine 40 supplied air mass flow and passes the measurement result to the engine control 20 further. The air mass meter 30 , the auxiliary loader 10 and the main loader 5 subsequently the fresh air is fed in 1 Inlet valve, not shown, the internal combustion engine 40 fed. Via an injection valve 35 becomes a combustion chamber of the internal combustion engine 40 Fuel supplied. According to 1 the fuel goes through the injector 30 injected directly into the combustion chamber. Alternatively, the fuel can also be in the area of the air supply 25 between the air mass meter 30 and the inlet valve are injected. This area is also known as the intake manifold. That in the combustion chamber of the internal combustion engine 40 Air / fuel mixture present is burned and thereby drives the internal combustion engine 1 on. The exhaust gas generated during combustion is fed into an 1 Exhaust valve, not shown, in an exhaust line 105 pushed out. The flow direction of the exhaust gas is in 1 also marked by an arrow. In the exhaust system 105 a turbine is optional 60 arranged of the exhaust gas turbocharger, which via a 1 stylized indicated wave 65 the main loader 5 drives to compress the fresh air supplied. The turbine 60 downstream in the flow direction of the exhaust gas is in the exhaust line 105 optionally a lambda probe 70 arranged. The lambda probe 70 measures the oxygen content in the exhaust gas and sends the measured value to the engine control 20 further. The engine control calculates the measured value and the known injection quantity 20 the actual air / fuel mixture ratio. The engine control can be used to achieve a desired air / fuel mixture ratio 20 then specify the injection quantity accordingly and the injection valve 35 control accordingly. On the internal combustion engine 40 is a speed sensor 45 arranged, the speed of the internal combustion engine 1 measures and the measurement result to the engine control 20 forwards. An exhaust gas recirculation line is also optional 50 provided the exhaust line 105 with the air supply 25 combines. The exhaust gas is between the internal combustion engine 40 and the turbine 60 from the exhaust line 105 via an exhaust gas recirculation valve 55 led away and via the exhaust gas recirculation line 50 between the main loader 5 and the internal combustion engine 40 into the air supply 25 guided. The direction of flow of the recirculated exhaust gas is in 1 also marked by an arrow. The exhaust gas recirculation valve 55 is also used by the engine control to adjust its degree of opening 20 driven. With the exhaust gas recirculation valve closed 55 there is no exhaust gas recirculation. With the exhaust gas recirculation valve open 55 the exhaust gas recirculation rate depends on the degree of opening of the exhaust gas recirculation valve 55 from. If like in this example 1 the internal combustion engine 1 drives a vehicle, as in
1 a control element shown in dashed lines 75 , for example an accelerator pedal, can be provided in order to specify a driver's desired torque. The accelerator pedal 75 is also with the engine control 20 connected.
The response behavior of the internal combustion engine is determined by the exhaust gas turbocharger 1 improved. Nevertheless, it comes with accelerations from a low speed or from a low load of the internal combustion engine 1 to delays in setting the desired torque. This can only be made available after a few seconds. The auxiliary loader is used to avoid this so-called turbo lag 10 provided that the intake air can be pre-compressed even with lower engine air mass flows. As a result, a higher boost pressure, a larger engine air mass flow, a larger injection quantity and thus more torque can be achieved. This can change the dynamic behavior of the internal combustion engine 1 be improved and a higher steady-state maximum torque can be achieved at low engine speed.
According to the invention, the auxiliary loader is now provided 10 only to be activated when it is needed. This is usually not the case at higher engine speeds and lower loads. The operation of the auxiliary loader is also the same 10 with activated exhaust gas recirculation, i.e. with the exhaust gas recirculation valve open 55 , not required or even annoying. Excessive compression in the air supply 25 could result in boost pressure in the air supply 25 greater than the exhaust gas back pressure in the exhaust system 105 is so that exhaust gas recirculation would no longer be possible.
According to the invention is therefore in the engine control 20 the functional diagram according to 2 realized in software and / or hardware. In the following, the injection quantity to be converted or set or the injected fuel mass mk is used as an example of the quantity for the load. Alternatively, the load can also be a torque to be set or implemented, for example the driver's desired torque or a torque specified by a driving or safety function, such as an anti-lock braking system, traction control or driving speed control, an output to be set or implemented, an air mass flow to be set or implemented, one filling to be set or implemented or a size derived from at least one of the stated sizes.
According to the functional diagram of 2 is a characteristic 85 provided, the input variable, the engine speed n of the internal combustion engine 1 and whose output quantity is a limit quantity mk_g for the fuel mass to be injected. The characteristic 85 describes the relationship between the engine speed n and the maximum value for the fuel mass to be injected, which is exceeded without the auxiliary charger operating 10 would lead to an impermissible exceeding of the so-called smoke limit. The characteristic 85 With increasing engine speed n there is an increasing limit quantity mk_g, since with increasing engine speed n the boost pressure achievable without an auxiliary charger and thus that of the internal combustion engine 40 supplied air mass increases and thus more fuel can be injected without reaching the smoke limit.
The limit set mk_g becomes a subtraction element 100 fed. The subtractor 100 is also the injected fuel mass mk directly or as in 2 shown after addition with an output of a differential time element 80 fed. The use of the differential time element 80 is optional. The input variable of the differential time element 80 is also the injected fuel mass mk. With the differential time element 80 can it be like in 2 acted as an example of a differential-time element of the first order. The step response is the differential time element 80 an exponential function decaying from a given initial value with a given time constant. With a constant injected fuel quantity mk, the output signal of the differential-time element is 80 equals zero. With a positive gradient of the injected fuel quantity mk, the output variable of the differential-time element therefore increases 80 at short notice. The output variable of the differential time element 80 is in an adder 95 added to the injected fuel mass mk. The result of the addition becomes the subtractor 100 fed. There is the sum of the adder 95 subtracts the limit set mk_g. The difference quantity mk_diff that forms becomes a characteristic diagram 90 supplied together with the engine speed n as an input variable. Output size of the map 90 is a target speed nEZV of the auxiliary loader 10 , The engine control 20 controls the auxiliary loader 10 such that the target speed nEZV for the compressor of the auxiliary charger 10 is set. The output size of the map 90 is 0 if the actual engine speed n is the input variable of the map 90 exceeds a predetermined value or the difference quantity mk_diff falls below a predetermined quantity value, for example zero. The predetermined value for the speed n is dependent, for example, on the performance of the auxiliary loader 10 and / or the electrical system load by the auxiliary loader 10 to apply. If this speed is exceeded, the turbo lag described above should no longer occur and the auxiliary charger 10 can be switched off in this case. If the actual engine speed n is above the specified value and the difference quantity mk_diff is greater than 0, the map gives 90 depending on the actual engine speed n and the difference quantity mk_diff an assigned target speed nEZV. The map 90 and the characteristic 85 can be applied on a test bench, for example. Likewise, for example, the initial value and the time constant of the step response of the differential time element 80 applied on the test bench.
The control of the auxiliary loader 10 through the engine control 20 can, for example, by a control signal in the form of a control duty cycle or a target current for the electric motor of the auxiliary charger 10 respectively.
The exhaust gas recirculation is usually active up to a maximum of an injected fuel quantity mk, which is smaller than the limit quantity mk_g. Therefore, the design of the function diagram follows 2 also the auxiliary loader 10 is not switched on with active exhaust gas recirculation. Otherwise the map would have to 90 have a further input variable that indicates whether the exhaust gas recirculation is activated or not, ie whether the exhaust gas recirculation valve 55 is open or not. If the exhaust gas recirculation valve is open 55 is then used as the output variable of the map 90 the target speed nEZV = 0 is output. Otherwise, the target speed is determined as described as a function of the engine speed n and the difference quantity mk_diff.
By using the difference-time link 80 it is possible to reduce the auxiliary load even with small loads, ie in this example with an injected fuel mass mk less than the limit mass mk_g the 10 to be activated when there is an acceleration request. This manifests itself in a positive time gradient of the injected fuel mass mk and thus in an additional offset to the injected fuel mass mk in the form of that via the adder 95 added output variable of the differential time element 80 , The sum lies at the output of the adder 95 then o above the limit quantity mk_g, then the auxiliary loader can 10 can also be activated for such low loads if there is a corresponding acceleration request.
The map 90 can be applied in such a way that for actual engine speeds n below the predetermined value and difference quantities mk_diff greater than 0, the target speed nEZV of the auxiliary loader 10 is increased when the actual engine speed n drops or the difference quantity mk_diff and thus the load increases. Conversely, the target speed nEZV can be reduced if the actual engine speed n increases or the difference quantity mk_diff and thus the load decreases.
Instead of in the form of an exhaust gas turbocharger, the main charger can 5 also be designed as a compressor or in any other manner known to those skilled in the art for compressing the fresh air supplied. Furthermore, the auxiliary loader 10 for example mechanically driven, for example, via a crankshaft of the internal combustion engine, the activation of the auxiliary loader 10 in this case, for example, by means of a bypass, the opening cross section of which can be done by means of a motor controller 20 controlled bypass valve can be set to a desired value. In this case, the engine control 20 no target speed is specified, but for example a compressor pressure ratio to be set via the auxiliary charger 10 or a boost pressure in the flow direction after the auxiliary charger 10 , Also in the described embodiment 1 and 2 the compression performance of the auxiliary loader can be changed to another instead of the set speed 10 representative variable, such as the compressor pressure ratio or the boost pressure, for controlling the auxiliary charger 10 be used.
When using the exhaust gas turbocharger, this can be equipped with a variable turbine geometry, which is controlled by the engine control, in order to achieve the desired boost pressure 20 is set according to the desired boost pressure. Alternatively, the desired boost pressure can also be obtained from the engine control by means of a wastegate in a manner known to those skilled in the art 20 can be set.
The control of the auxiliary loader 10 to set the desired target speed nEZV and the control of the exhaust gas turbocharger to set the desired turbine geometry, for example, both act on the control variable "boost pressure" and each take place with the help of an in 1 Not shown actuator. Only one of the two actuators is regulated, the other is controlled. This enables stable stationary operation in the entire engine operating range. In the example described here, the exhaust gas turbocharger is controlled by means of the variable turbine geometry and the auxiliary charger 10 controlled.
and the device according to the invention
can be used in a corresponding manner in a gasoline engine.