JP2005537431A - Method of operating an internal combustion engine - Google Patents

Abstract

The present invention relates to a method for operating an internal combustion engine (10), the internal combustion engine having at least one injection valve (30), which comprises a control device (34) for the internal combustion engine (10). A piezoelectric actuator (58) to which a drive control signal is applied is assigned by the control circuit, and the piezoelectric actuator corresponds to the drive control signal with respect to the fuel injection by changing the needle stroke of the valve needle (44) of the injection valve (30). To cause. The drive control signal is varied depending on the drive control output received by the piezoelectric actuator (58) to increase the output of the internal combustion engine (10). Similarly, the temperature of the control device (34) can be lowered.

Description

The present invention relates to a method for operating an internal combustion engine. Here, the internal combustion engine has at least one injection valve, and a piezoelectric actuator to which a drive control signal is applied by a control device of the internal combustion engine is assigned to the injection valve. This piezoelectric actuator causes a needle stroke of the valve needle of the injection valve corresponding to the drive control signal for fuel injection.

  The invention further relates to a control device for an internal combustion engine. Here, the internal combustion engine has at least one injection valve, and a piezoelectric actuator to which a drive control signal is applied by a control device of the internal combustion engine is assigned to the injection valve. This piezoelectric actuator causes the needle stroke of the valve needle of the injection valve corresponding to the drive control signal to occur for fuel injection.

  Furthermore, the present invention relates to a computer program for a control device for an internal combustion engine. Here, the internal combustion engine has at least one injection valve, and a piezoelectric actuator to which a drive control signal is applied by a control device of the internal combustion engine is assigned to the injection valve. This piezoelectric actuator causes the needle stroke of the valve needle of the injection valve corresponding to the drive control signal to occur for fuel injection.

  The conventional method of operation of the type described at the beginning has the following drawbacks. That is, the rotational speed above the internal combustion engine, in particular due to the loss output replaced in the piezoelectric actuator during multiple injections and the limited drive control output supplied from the control device or the final output of the control device. The limit is set and the maximum output of the internal combustion engine is limited.

  The final output stage typically includes a direct current to direct current (DC / DC) converter. The output of this DC / DC converter is not arbitrarily increased from a cost standpoint and by the available built-in space. From the upper rotational speed limit mentioned above, the drive output of the DC / DC converter is no longer sufficient to compensate for the lost energy converted in the piezoelectric actuator. In addition, the controller becomes unacceptably high when the DC / DC converter is heated.

  A further disadvantage of the known method is that it is necessary to discharge the loss output from the piezoelectric actuator in order to avoid overheating the actuator.

  Accordingly, an object of the present invention is to provide an improved operating method, control device, and computer program that can increase the output of an internal combustion engine and at the same time reduce the loss output converted in the piezoelectric actuator. .

  The above-mentioned problem is solved in an operating method of an internal combustion engine of the type described at the outset by changing the drive control signal in dependence on the drive control signal received by the piezoelectric actuator.

  As a result, the drive control signal can always be selected or reduced as follows. That is, the drive control signal can be selected or reduced so as to ensure more reliable operation of the internal combustion engine and sufficient loss of heat release from the piezoelectric actuator. Furthermore, in this way it is ensured that the control device temperature is always kept within an acceptable range.

  As soon as the drive control signal controlling the piezoelectric actuator is reduced compared to the reference value, the mechanical extension of the corresponding piezoelectric actuator and thus the corresponding needle change of the injection valve is also reduced. When the amount of change in the needle is reduced, the loss energy converted in the piezoelectric actuator is smaller than when the actuator is driven and controlled by the reference value. Therefore, when the operation method according to the present invention is used, a smaller amount of thermal energy is released from the actuator. Is done. Similarly, the loss energy replaced in the final output stage is reduced, thereby reducing the temperature of the controller.

  When the needle displacement is reduced, the static flow of fuel through the injector is also reduced, so that when using the method according to the invention with a reduced needle displacement, the same amount of fuel as in the conventional drive control is used. In order to inject into the combustion chamber, the injection time must be increased accordingly.

  For example, in order to avoid contamination caused by particles being trapped in the opening of the injection valve, a limit on the minimum needle displacement and thus the corresponding minimum drive control signal should be established.

  Another very advantageous advantage of the method of operation according to the invention is that the output of the internal combustion engine can be increased. This is done by raising the upper rotational speed limit for multiple injections over conventional methods.

  As described above, according to the present invention, a slight loss energy is converted in the piezoelectric actuator by reducing the amount of needle displacement per time. Such savings (ie relative to the maximum allowable loss energy compensated by the DC / DC converter) are used to operate the internal combustion engine at higher speeds and multiple injections. Here, the loss energy converted in the piezoelectric actuator increases again due to the proportionality to the rotational speed. It is therefore possible to operate the internal combustion engine at the same maximum output of the DC / DC converter, at a higher maximum rotational speed with multiple injections and thus at a higher maximum output of the internal combustion engine.

  In an advantageous embodiment of the method according to the invention, the drive control signal is reduced to a maximum value if a predetermined maximum drive control output is exceeded. The maximum drive control output corresponds to, for example, a predetermined maximum rotational speed of the internal combustion engine at the time of multiple injection. By selecting the maximum value accordingly, it is possible here to reduce the amount of needle change. As a result, when the loss output in the piezoelectric actuator is the same, the rotational speed of the internal combustion engine at the time of multiple injection is increased.

  A particularly simple embodiment of the method according to the invention is characterized in that the maximum value is a constant. In such an embodiment, the drive control signal for the piezoelectric actuator is set to a certain maximum value when it exceeds a predetermined maximum drive control output and thus a corresponding maximum rotational speed.

  In another advantageous embodiment of the invention, this maximum value is selected, for example, depending on the characteristic curve stored in the memory of the controller.

  Since this characteristic curve can be applied in the same way as a certain maximum value, the corresponding value can be changed even after the internal combustion engine is started. The maximum drive control output can also be advantageously applied to improve flexibility.

  Particularly advantageously, in another form of the invention, the drive control output received by the piezoelectric actuator is calculated from the operating quantity of the internal combustion engine. In this way, the drive control output necessary for the operation of the actuator is monitored. Here, the drive control output can be obtained only from the amount existing in the control devices of all the internal combustion engines. That is: the loss energy of the actuator for each needle stroke, the number of injections per cycle and the rotational speed of the internal combustion machine.

  In another form of the method according to the invention, the drive control output received by the piezoelectric actuator is detected by a measurement technique. For this purpose, for example, the amount of charge flowing through the piezoelectric actuator and the corresponding charging time and possibly another amount are detected.

  As a further means for solving the problems of the present invention, a control device for an internal combustion engine is proposed. The internal combustion engine has at least one injection valve, and a piezoelectric actuator to which a drive control signal is applied by a control device is assigned to the injection valve, and the piezoelectric actuator corresponds to the drive control signal. The needle stroke of the valve needle of the valve is caused for fuel injection. In this control device, the drive control signal can vary depending on the drive control output received by the piezoelectric actuator.

  Furthermore, as another means for solving the problems of the present invention, a computer program suitable for carrying out the method according to the present invention is proposed in the computer program of the format described at the beginning. This computer program is advantageously stored in an electrical storage medium, in particular a flash memory or a read-only memory.

  Further features of the invention and methods of use and advantages are described in the description of the examples of the invention below. An example is illustrated. All features shown herein are themselves or in any combination, do not depend on summaries or dependencies in the claims, and do not depend on the description or drawings, Configure configuration requirements.

FIG. 1 shows an embodiment of the method according to the invention. This method is used in the internal combustion engine 10 indicated by the one-dot chain line in FIG. 2 to increase the maximum rotation speed and thus the maximum output of the internal combustion engine. The internal combustion engine 10 has injection valves 30a, 30b, and 30c. The fuel is directly injected into the combustion chambers 32a, 32b, 32c of the cylinders 33a, 33b, 33c from the fuel accumulation line 26. The injection valves 30a, 30b, 30c are controlled by the control device 34 of the internal combustion engine 10.

  The detailed structure of the injection valves 30a, 30b, 30c is shown in FIG. In FIG. 3, an injection valve 30 is shown as an example. Each injection valve 30 a, 30 b, 30 c has a piezoelectric actuator 58. This piezoelectric actuator drives the valve needle 44 of each injection valve 30a, 30b, 30c.

  The distance traveled by the valve needle 44 (also referred to as a needle change amount) is proportional to the drive control signal. This drive control signal is applied to the piezoelectric actuator 58 from the control device 34 (FIG. 2) of the internal combustion engine 10 via the line 70 (FIG. 3).

  This drive control signal is generated in the controller 34 by a DC / DC converter (not shown). In this embodiment, this DC / DC converter advantageously supplies drive control signals to all piezoelectric actuators 58 of the injection valves 30a, 30b, 30c (FIG. 2) of the internal combustion engine 10. Since the piezoelectric actuator 58 is a component having substantially capacitive characteristics, an amount of charge proportional to the drive control signal flows to / from the actuator 58 during drive control by the drive control signal.

  The electrical energy supplied from the DC / DC converter for driving control of the piezoelectric actuator 58 includes the number of cylinders 33a, 33b, 33c of the internal combustion engine 10, the loss output of the piezoelectric actuator 58 depending on the needle stroke, This results from the product of the number of drive controls of the actuator 58 and the rotational speed of the internal combustion engine 10 for each injection cycle. Here, such electric energy is hereinafter referred to as total drive control energy.

  In a first step 110 of the method according to the invention (FIG. 1), the drive control output for this total control energy is evaluated. This drive control output is received by the piezoelectric actuator 58 of the injection valves 30a, 30b, 30c of the internal combustion engine 10, and the valve needle 44 of the injection valves 30a, 30b, 30c is moved.

  While the DC / DC converter included in the controller 34 can supply all control energy for a time set by the rotational speed of the internal combustion engine 10 (this is actually the case in step 120 of FIG. 1). The amount of needle change in the injectors 30a, 30b, 30c is conventional in accordance with the following step 130, by comparing the drive control output received by the actuator 58 with the predetermined maximum drive control output applicable). Set to That is, the maximum needle stroke amount of the valve needle 44 is set by the drive control signal.

  Subsequently, in step 150, fuel is injected into the combustion chambers 32a, 32b, 32c (FIG. 2) of the cylinders 33a, 33b, 33c.

  However, as a result of the comparison between the drive control output actually received by the actuator 58 and the predetermined maximum drive control output in step 120, the DC / DC converter is fully at a given rotational speed and multiple injections of the internal combustion engine 10. When it is found that the drive control output can no longer be used, the piezoelectric actuator 58 is no longer drive controlled in the present invention as in the prior art, and first branches to a query step 140, as shown in FIG. .

  Regardless of the results of the query 140 described below, the piezoelectric actuator 58 is driven and controlled by the reduced drive control signal after the query 140. This produces a reduced needle change and thus a reduced total drive control energy. Nevertheless, in order to obtain the same injection amount as in the conventional drive control with the maximum needle stroke amount compared to step 130, the drive control time is correspondingly extended.

  In step 140, the status flag is subsequently queried by the control device 34 of the internal combustion engine 10. This represents how the needle stroke of the injection valves 30a, 30b, 30c should be limited. On the other hand, the drive control signal is set to a constant maximum value in step 142. On the other hand, in the method of FIG. 1, the maximum value for the drive control signal can also be selected in step 144 depending on the characteristic curve. This characteristic curve is stored in the memory of the control device 34.

  Certain maximum values and characteristic curves are applicable, so that the stored values can always be adapted.

Similarly to step 130, after setting the drive control signal in steps 142 and 144, fuel is injected into the combustion chambers 32a, 32b and 32c of the cylinders 33a, 33b and 33c in accordance with step 150. When the rotational speed is the same, the actuator 58 is compared with the drive control of the actuator 58 with the maximum needle change amount by reducing the needle change amount during the drive control of the piezoelectric actuator 58 corresponding to 144. The drive control output that is accepted is reduced. As a result, the thermal energy released from the actuator 58 is similarly reduced. In addition, the temperature of the control device 34 is correspondingly reduced.

  Alternatively, the internal combustion engine 10 is operated even at high rotational speeds using drive control according to the present invention with a reduced needle change. Moreover, the total drive control energy resulting from the DC / DC converter will not be unacceptably high. Here, the output of the internal combustion engine 10 increases.

  The drive control output actually received by the actuator 58 required for the above comparison in step 120 is determined in this case by calculating the amount of operation of the internal combustion engine 10 as described above.

  Alternatively, the drive control output actually received by the actuator 58 can be detected by a measurement technique. This is done by detecting the amount of charge flowing through the piezoelectric actuator 58 and the corresponding charge time and possibly another amount of the internal combustion engine 10.

5 is a flowchart of an embodiment of a method according to the present invention. The figure showing the internal combustion engine by this invention. The figure showing the injection valve of the internal combustion engine described in FIG.

Claims (10)

A method for operating an internal combustion engine (10), comprising:
The internal combustion engine has at least one injection valve (30), and a piezoelectric actuator (58) to which a drive control signal is applied by a control device (34) of the internal combustion engine (10) is assigned to the injection valve. And
In a method of the type in which the piezoelectric actuator causes a needle stroke of the valve needle (44) of the injection valve (30) corresponding to the drive control signal to fuel injection,
Changing the drive control signal depending on the drive control output received by the piezoelectric actuator (58);
An operating method of an internal combustion engine, characterized in that   The method of claim 1, wherein the drive control signal is reduced to a maximum value when a predetermined maximum drive output is exceeded.   The method of claim 2, wherein the maximum value is a constant.   The method according to claim 2, wherein the maximum value is selected depending on a characteristic curve.   5. The method according to claim 2, wherein a characteristic curve for the maximum drive control output and / or the maximum value and / or the maximum value is applied.   The method according to any one of the preceding claims, wherein the drive control output received by the piezoelectric actuator (58) is calculated from the amount of operation of the internal combustion engine (10).   The method according to any one of the preceding claims, wherein the drive control output received by the piezoelectric actuator (58) is detected by a measurement technique. A control device (34) for the internal combustion engine (10),
The internal combustion engine has at least one injection valve (30), and a piezoelectric actuator (58) to which a drive control signal is applied by the control device (34) is assigned to the injection valve,
In the piezoelectric actuator, the needle stroke of the valve needle (44) of the injection valve (30) corresponding to the drive control signal is generated for fuel injection.
The drive control signal can vary depending on the drive control output received by the piezoelectric actuator (58),
A control device for an internal combustion engine. A computer program for a control device (34) of an internal combustion engine (10) comprising:
The internal combustion engine has at least one injection valve (30), and a piezoelectric actuator (58) to which a drive control signal is applied by the control device (34) is assigned to the injection valve,
In the piezoelectric actuator, the needle stroke of the valve needle (44) of the injection valve (30) corresponding to the drive control signal is generated for fuel injection.
The computer program is suitable for carrying out the method according to any one of claims 1 to 7,
A computer program for a control device for an internal combustion engine.   The computer program according to claim 9, wherein the computer program is stored in an electrical storage medium, in particular a flash memory or a read-only memory.

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