DE102011003681A1 - Method and device for adjusting the operating state of an internal combustion engine - Google Patents

Abstract

The invention relates to a method for changing the operating state of an internal combustion engine. Data characteristic of the operating state of the internal combustion engine are recorded by at least one sensor and forwarded to a control device. With the control device, an optimal operating range of the internal combustion engine is determined on the basis of the data, and the operating state of the internal combustion engine is specifically adapted to the optimal operating range in that a setpoint is determined for at least one engine operating parameter that is decisive for the combustion process, which is to be maintained or achieved of the optimal operating range is required, and the actual value of the engine operating parameter is regulated to the setpoint.

Description

The present invention relates to a method for changing the operating state of an internal combustion engine according to claim 1. The invention further relates to the use of the method according to claim 9 and also an apparatus for performing the method according to claim 10 and a control device therefor according to claim 11 ,

The use of an internal combustion engine is preferably carried out within an optimal operating range tailored to the intended use of the engine. A common optimum operating range is, for example, characterized in that the fuel consumption during operation is minimized. The operating state of the internal combustion engine is therefore preferably kept in this optimum operating range. However, the quality of the combustion of a used fuel-air mixture and thus the operating state depends on numerous operating conditions, which can not be kept constant, such as the fuel composition, the intake air temperature, the fuel quality, the residual gas content in a cylinder, etc.

During engine operation, therefore, the optimum operating range can be left. When leaving the optimum operating range, sometimes undesirable phenomena occur, such as knocking of the engine. Under such conditions, methods are known which allow to recognize leaving the optimum operating range. To avoid damage to the engine, it is important to stop knocking as quickly as possible. There are therefore used in the operation of known internal combustion engines methods for knock control and anti-knock devices, as for example, in the DE10360022A1 have been disclosed.

If a knocking occurs, a retardation of the firing angle is made in a knock-resistant area according to the described method, whereupon at least one measure from a catalog is initiated in order to prevent the knocking in the original operating point. If it is determined that a measure does not lead to the desired destination and the knocking continues at the original operating point, the measure is deleted from the said catalog and a subsequent alternative measure from the catalog is tested. The aim of the known method is to return to the original operating state, and to let the engine continue to operate without knocking.

The operating state of the internal combustion engine is temporarily changed in accordance with the known method, attempts are made to eliminate a cause of knocking, and the process is returned to the original operating state upon successful completion of the process. This method has the disadvantage that permanent changes in operating conditions are not taken into account. It is therefore possible that knocking in the original operating state is prevented from succeeding, and the described method does not lead to a result. Restoring the original operating state is impossible under the changed operating conditions. The motor thus operates knocking, or at most with reduced power in a non-optimal operating range, or it must be turned off.

It is therefore an object of the present invention to provide a method with which it is possible to react to temporary or permanent changes in the operating conditions. An internal combustion engine operated in this way should also work optimally if the operating conditions have changed permanently and restoration of the original operating state is not possible. In addition, a device intended for carrying out the method and a control device suitable therefor are to be provided.

The invention solves this problem with regard to the method with the features according to claim 1. The use of the method and the apparatus for carrying out the method are described in the independent claims 9 and 10, a control device is specified in claim 11. Advantageous embodiments are described in the further claims.

According to the method of the invention, it is proposed to change the operating state of an internal combustion engine by means of at least one sensor and a control device and to detect with a sensor data that are characteristic of the operating state of the internal combustion engine, and forward this data to a control device and with the control device to determine, based on the data, an optimum operating range of the internal combustion engine and to adapt the operating state to the optimum operating range. This adjustment is made by the controller determining, at least for an engine operating parameter that determines the combustion process, a setpoint required to maintain or reach the optimum operating range, and the actual value of the engine operating parameter is controlled to the setpoint.

If a sudden change in the combustion of the engine is detected at constant engine operating parameters (for example, ignition timing, combustion air ratio, ignition duration, air mass flow), then it can be concluded that one or more operating conditions (for example fuel composition) have changed. However, as operating conditions have changed, the optimum operating range also shifts with respect to the engine operating parameters considered, ie, it can be concluded, for example, that the fuel composition has changed.

According to the proposed invention, the controller determines a new optimal operating range, for example, taking into account known engine maps, which were determined for example with different reference fuels or tailored to other operating conditions. If the engine is still operating in an optimal operating range, the controller will maintain the current optimum operating range.

Once the optimum operating range has been left for the engine operating parameters to be taken into account, optimized engine operating parameters are determined for the new optimum operating range and the current engine operating parameters are updated as the actual value to the new optimized engine operating parameters as setpoint.

The control device used is, for example, a motor control, which can optionally be supplemented by appropriate functionalities on the basis of an available engine control so that a cost-effective and add-on-capable implementation is possible.

For the implementation of the procedure explained above, the control device determines a desired value for at least one engine operating parameter, which determines the combustion process. Setpoints are selected according to the invention so that the optimum operating range is maintained when the currently detected operating condition is already in the optimum operating range, and if the current operating condition is not within the optimum operating range, this is performed directly or gradually in the optimum operating range by the actual value of the motor operating parameter is regulated to the setpoint. The advantage is that this adaptation of the engine operating parameters extends the range of application in which the internal combustion engine can be optimally operated. A sustainable adaptation of the engine operating parameters to permanently changed operating conditions could be carried out according to the prior art only by manual intervention.

According to a preferred embodiment, knock values or variables dependent thereon are determined as data. For this purpose, a knock sensor, for example, a generic piezoelectric vibration sensor - for example, with integrator for signal amplification - used. An often existing sensor can thus be used to carry out the claimed method. The method can be inexpensively implemented for use on available internal combustion engines. If, for example, a knock is detected, this serves as a reason for changing the operating state. The method according to the invention can supplement or replace a knock control method implemented in the engine control.

Another possibility is the use of a pressure sensor, for example, for detecting Zünddruckwerten. The characteristic of the operating condition of the engine data in this case include Zünddruckwerte, d. H. Measured actual values (snapshots) of the rapidly changing ignition pressure, dependent variables or the entire ignition pressure curve. In addition to pressure sensors, other sensors can also be used; the method can be adapted to the sensors available in conjunction with a specific internal combustion engine.

The operating state of the internal combustion engine can be determined on the basis of one or more variables. Suitable parameters are the engine speed, torque values, ignition pressure values, the mean pressure prevailing during an ignition process, the combustion air ratio λ, ignition time t, ignition duration, ignition pressure profile, ignition energy, spark duration, temperature, etc. In this way, the method can be adapted to different engines, the Operating state, for example, is determined such that existing sensors are used.

The optimum operating range of the engine, which depends on the respective operating conditions, such as the fuel composition, is adapted to the specifications resulting from its intended use of an internal combustion engine. As an optimal operating range, for example, an efficiency range is specified as a function of the operating conditions. For each operating condition, for example, there is an operating point with minimal fuel consumption. The operating range in which the fuel consumption is sufficiently close to the predetermined minimum, in this case as an efficiency range be specified. For each operating condition, therefore, an optimal operating range is given. Another example is to define the efficiency range by the fact that the emission values during operation must be within a predetermined interval. To determine optimal operating ranges, experience data such as engine maps can be used.

According to the invention, as the combustion process determining engine operating parameters combustion air ratio λ, ignition timing t, engine speed, torque, ignition energy, spark duration and / or a dependent of at least one of these engine operating parameters size can be used. Which engine operating parameters are used can in turn be tailored to a specific internal combustion engine and / or a specific use of the internal combustion engine.

For at least one engine operating parameter, the controller specifies setpoints. If required, these can be restricted to a specified value range. A limited range of values may be useful because certain engine operating parameters such as ignition timing t should be within defined limits to protect the engine from improper settings or to comply with emissions regulations. An inadmissible setting would be, for example, an ignition point too early, which would certainly trigger a knocking combustion. Emissions regulations, for example, play a special role in industrial stationary gas engines.

According to a preferred embodiment of the invention, a predetermined value interval is set for a desired value to be determined as a function of the operating state of the internal combustion engine. In certain operating conditions, it may be useful to allow a large value interval while for others a smaller one is suitable. If a large value interval is permitted for the setpoint, a change in the actual value with a large increment (the difference between the setpoint and the current actual value) can be made. This is u. a. then makes sense, if a knock was found. Then the internal combustion engine operates in a hazardous area and the operating state should be changed very quickly. An interesting determining factor in this context is, for example, the ignition point. When the engine starts knocking, the interval for a given target ignition timing can be made large, and the ignition timing is quickly set to a much later value. The increment of change is so great. Once the engine has left the danger zone and a new setpoint is established, the fine adjustment may begin, and therefore a much smaller increment for changing the ignition timing may be selected, and the ignition timing will now be changed gradually, more slowly towards early. In this second phase of the control, small value intervals are specified for the setpoint values, and the actual value of the engine operating parameter is controlled successively, in several steps, to a series of setpoint values.

If it is determined that the operating state of an internal combustion engine is already within the optimum operating range adapted to the current operating conditions, very small or even no changes can be made to a desired value, the intervals are then selected to be very small. This optimizes the control process. This also brings about an optimization of the efficiency of the internal combustion engine, and also prevents increased wear or other risks.

To define a desired value of an engine operating parameter, in particular the ignition timing t and / or the combustion air ratio λ, engine maps can be used. Such engine maps are particularly dependent on fuel parameters. Engine maps can therefore be determined with different reference fuels. For this purpose, for example, contractually guaranteed fuels can be used. It can therefore be used engine maps, which were determined with different fuels with different composition. By means of different engine maps, setpoint values can be found quickly in the event of a changing operating state, and a successive control of one or a whole series of desired values can be undertaken. In this way, a directional adaptation of the operating state, whereby any known empirical data can be taken into account. It is therefore not a trial and error procedure, which tests in turn measures, but a precise, based on accurate knowledge of the particular internal combustion engine control.

The method can be applied to various internal combustion engines, in particular to gas engines, or more specifically to gas Otto engines. For gas engines, it is common phenomenon that the composition of the fuel gas used changes over time. By means of the method according to the invention, it is possible to dynamically set an optimum operating range of the engine for each gas composition.

To carry out the method, a device is preferably used which has a Has sensor and a control device. The sensor determines data that is characteristic of the operating state of an internal combustion engine, and forwards it to the control device. The controller continuously determines an optimal operating range of the internal combustion engine based on the data, and determines a setpoint required to maintain or achieve the optimum operating range for at least one engine operating parameter that determines the combustion process and adjusts the actual value of the engine operating parameter to the setpoint.

Among other things, the control device according to the invention uses a suitable algorithm, which determines an optimum operating range from the data transmitted by a sensor, which are characteristic of the operating state of an internal combustion engine. In addition, this determines a setpoint that is required for maintaining or reaching the optimum operating range, at least for a determining for the combustion process engine operating parameters, and outputs a signal that is used to control the actual value of the engine operating parameter to the setpoint. This algorithm can, depending on the embodiment, involve very different parameters of the combustion process, and can use all given empirical data. Preferably, this algorithm uses different engine maps, which may be tailored to different fuels or different fuel composition, for example.

The invention will now be described by way of example with reference to the accompanying drawings. Show it:

1 a schematic block diagram representation of an embodiment of the inventive method for changing the operating condition of an internal combustion engine;

2a - 2d a representation of various operating conditions and operating ranges of an internal combustion engine;

3 a block diagram representation of an embodiment of a device for changing the operating condition of an internal combustion engine.

1 shows in conjunction with 3 a block diagram of a method and apparatus for controlling the operating condition of an internal combustion engine according to an embodiment of the present invention. sensors 2 detect in a first step S1 data, due to which in the course of the following steps, as will be explained in more detail below, a control process by means of an engine control unit 1 is made.

The device has an engine control unit in the illustrated embodiment 1 and several sensors 2 on. From the ones from the sensors 2 transmitted data determines the engine control unit 1 the operating state (Z1) and an optimum operating range of the engine (W), and controls predetermined engine operating parameters, so that the operating state (Z1) remains in the optimum operating range (W), or in an optimal operating range (Wn) is performed.

In the internal combustion engine, not shown, the embodiment shown is a stationary gasoline gasoline engine. The sensors 2 In this illustrated embodiment, a knock sensor is included 3 in the form of a piezoelectric vibration sensor with integrator, also an engine speed sensor 4 , a pressure sensor 5 , which is used to measure ignition pressure values, and a torque sensor 6 ,

The knock sensor determines data that is characteristic of the operating state of the engine (Z1), in this case, knock values are detected as data. The ones from the sensors 2 The data collected is via data connections 7 to the engine control unit 1 transfer. By means of an algorithm 8th becomes from the transmitted data in the engine control unit 1 a current operating state of the gas engine (Z1) determined.

The current operating state Z1 of the gas engine is in 2a represented as a point (Z1). The two coordinate axes in the illustrated diagram symbolize different, the operating state of the gas engine characterizing variables such as engine speed, engine torque, combustion air ratio A, ignition timing, ignition duration, etc.

The algorithm 8th of in 3 illustrated engine control unit 1 also detects one of the, from the sensors 2 transferred data dependent, optimal operating range W. This is in 2a shown as a hatched, circular area. In this operating range W, the gas engine works optimally. The optimum operating range W is a sufficiently small range around an optimal operating point. In the present case, this area can be understood to mean that fuel consumption in this area is minimal. 2a thus represents the desired operating situation, for the optimum operating range W relevant engine operating parameters of the gas engine were properly adapted by the engine control unit, and the like reached operating state Z1 is in the optimum operating range W.

1 schematically illustrates the method for changing the operating state. The just described detection of the sensor signals is in 1 represented as step S1. The determination of the current operating state Z1 and of the optimum operating range W takes place as step S2. in the next step S3, the algorithm determines 8th of the engine control unit 1 Whether the operating state Z1 is located in the optimum operating range W. If so, as in 2a illustrated, the operating state Z1 is maintained or slightly modified in the sense of a fine adjustment by the engine control unit 1 the engine operating parameters are kept constant or slightly fine, and the process starts the same process again. This is shown as returning from step S3 to step S1.

To carry out the described method uses the engine control unit 1 as the engine operating parameter in the illustrated embodiment, the ignition timing t and the combustion air ratio λ. In the case just described - the operating state is in the optimum operating range - leave the engine control unit 1 the setpoint values for the ignition timing t and the combustion air ratio λ invariant. The regulation of these two parameters is in 3 with the data and control lines 9 and 10 shown - the two arrow directions symbolize that a regulation is made- and it takes place on the corresponding engine or machine components 11 , in the case shown on a device 12 for measuring and changing the ignition time t and a device for measuring exhaust gas 13 or determination of the combustion air ratio λ.

Represents the algorithm 8th However, it is determined that the operating state Z1 of the gas engine is outside the optimum operating range W, the operating state Z1 must be changed and adjusted accordingly. In the illustrated embodiment, two combustion engine operating parameters used to change the operating state are used, on the one hand the ignition timing t, and on the other hand the combustion air ratio λ. The control is performed by setting the target values for the ignition timing t and the combustion air ratio λ.

To explain the illustrated embodiment, it is assumed that the gas composition of the fuel gas used has changed, and therefore ignition timing t and combustion air ratio λ are no longer suitable for optimal combustion. Changes in a fuel gas relate, for example, hydrocarbons or the proportion of inert gases, etc.

Changes in these components or their proportions in the gas have effects on methane number, burning rate, calorific value etc. The optimum operating range W was tailored to the old gas composition, while the new gas composition requires an optimum operating range Wn (Wn stands for "W new"). The starting point for this case is in 2 B shown. The operating state Z1 is outside the optimum operating range Wn.

In addition, it should be assumed for the sake of illustration that the gas engine has begun to knock. As in 2 B Thus, the operating state Z1 now falls into an operating region K, which represents a danger zone, namely a zone in which the engine is knocking, the process as in FIG 1 is not returned from step S3 to step S1, but proceeds to step S4, it is by means of the algorithm 8th set other setpoints for the ignition timing t and the combustion air ratio λ. For this purpose, empirical data, in particular engine maps-representing, for example, the optimum ignition timing and the combustion air ratio as a function of engine speed and ignition pressure, etc.-are used and in the algorithm 8th used.

In determining the new setpoints in step S4, the algorithm controls 8th whether the setpoints remain within a given value interval. This prevents inadmissible settings being made, for example, a too rich mixture is used, which would lead to operation with too high emissions. The predetermined value intervals, in which these setpoints must be, also depend on the current operating state Z1 of the gas engine. In the case shown (see 2 B ) Z1 is in a knocking range K, the value interval is therefore chosen large, since a large increment in the change of the setpoint values, namely the ignition timing t and the combustion air ratio λ, is to be achieved.

By regulating the actual values of the ignition time t and the combustion air ratio λ to the desired values, a new operating state Z2 is quickly reached. This is in 2c shown. The operating state Z2 is now outside the knocking region K, but not yet in the optimum operating region Wn. In a control step, a large change in the engine operating parameters and thus the operating state was made. A large value interval has been set for the setpoints, thus achieving a large increment of change.

In the context of the control process just described, in a step S5 of the method Checks whether the actual values for the two engine operating parameters correspond to the nominal values. As soon as this is the case, the system returns to step S3 and checks whether the operating state Z2 lies in the new optimum operating range Wn. If this is the case, the process returns to step S1: the process starts again. This is in the in 2c Z2 is not in the new optimum operating range Wn, the method returns to step S4: the setpoints are reset.

Since the engine is no longer in a knocking area, the value intervals for the setpoint values of the two engine operating parameters used in the illustrated embodiment are set smaller. The following control processes are a fine adjustment of the engine operating parameters. The primary goal of the fine adjustment, in contrast to the adjustment with large increments, not to change the operating state of unwanted operating conditions to desired as fast as possible to escape a danger, but to achieve the optimum operating range Wn accurately and without detours. For this purpose, a small value interval for the setpoint values is specified, and thus a small increment of the change is achieved. Therefore, a set of setpoints are set to which the actual values of the engine operating parameters are successively controlled. One possibility is also that after reaching a respective setpoint, the next setpoint is set again or for the first time. In this way, the operating state of the gas engine is successively guided to the state Z3. The goal state of this successive process is in 2d shown, the operating state Z3 is again in the optimum operating range Wn.

The gas engine can now continue to operate and there is no need to attempt to restore the original Z1 operating condition. The optimal operating range has finally shifted as a result of the altered gas composition. The old operating range W was optimal for the old gas composition, the operating range Wn is optimal for the new gas composition. The described method takes account of this change and continuously optimizes the operation of the engine in response to dynamically changing operating conditions.

LIST OF REFERENCE NUMBERS

1

Engine control unit, control device

2

sensors

3

knock sensor

4

Engine speed sensor

5

pressure sensor

6

torque sensor

7

data connections

8th

algorithm

9

Data and control line

10

Data and control

11

Engine or machine components

12

Device for measuring and changing the ignition timing

13

Device for measuring exhaust gas

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 10360022 A1 [0003]

Claims (11)

Method for changing the operating state of an internal combustion engine, characterized in that at least one sensor ( 2 ) recorded for the operating condition (Z1) of the internal combustion engine characteristic data and to a control device ( 1 ) and by the regulatory body ( 1 ) is determined based on the data an optimal operating range (W) of the internal combustion engine and the operating condition (Z1) of the internal combustion engine to the optimum operating range (W) is adjusted by at least for a motor operating parameter, which is determined for the combustion process, a target value is determined to maintain or reach the optimum operating range (W) is required, and the actual value of the engine operating parameter is controlled to the setpoint. A method according to claim 1, characterized in that a knock value, an ignition pressure value, a Zünddruckverlauf and / or dependent thereon variables are detected as data. Method according to claim 1 or 2, characterized in that the operating state (Z1) of the internal combustion engine is determined on the basis of at least one variable selected from a group comprising speed, torque, mean pressure, combustion air ratio λ, ignition time t, ignition pressure curve, ignition energy, spark duration or a size dependent thereon. Method according to one of the preceding claims, characterized in that an efficiency range dependent on the data is determined as the optimum operating range (W). Method according to one of the preceding claims, characterized in that a desired value for at least one engine operating parameter, in particular combustion air ratio λ, ignition time t, engine speed, torque, ignition energy, spark duration is determined. Method according to one of the preceding claims, characterized in that the desired value of a motor operating parameter is determined within a predetermined value interval. A method according to claim 6, characterized in that the predetermined value interval depending on the current operating state (Z1) is selected. Method according to one of the preceding claims, characterized in that the desired value for the ignition time t and / or the combustion air ratio λ is determined taking into account predetermined engine maps, which are dependent in particular on fuel parameters. Use of the method according to one of the preceding claims for controlling the operating state of a gas-fired gasoline engine. Device for carrying out the method according to one of the preceding claims, characterized by at least one sensor ( 2 ) for acquiring data that is characteristic of the operating state (Z1) of an internal combustion engine, and a control device ( 1 ) which determines an optimum operating range (W) dependent on the data and determines, at least for a combustion engine process determining engine operating parameter, a setpoint required to maintain or reach the optimum operating range (W) and regulates the actual value to the setpoint. Control device ( 1 ) for changing the operating state of an internal combustion engine in dependence on data which are characteristic for the operating state, and the control device ( 1 ) determines an optimum operating range (W) and determines at least one desired value of a combustion process determining engine operating parameter required to maintain or reach the optimum operating range (W) and outputs a signal to control the actual value of the engine operating parameter to the target value.

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