KR20030009226A - Method for operating an engine, in particular a direct injection engine, computer program, and control and/or regulation unit - Google Patents

Abstract

PURPOSE: A method for operating a direct injection-type engine, a computer program, and a control/regulation unit are provided to easily and reliably remove impurities in an injector and to prevent the injector from being polluted. CONSTITUTION: A method for operating a direct injection-type engine makes fuel be supplied to at least one fuel injector(30) and injected into at least one combustion chamber. At least one area adjacent to at least one flow-out opening(50) of the fuel injector receives high frequency vibration for at least constant time. A valve element(44) of the fuel injector receives the high frequency vibration for a constant time within at least one area of an opening step. In addition, the valve element is moved by a piezoelectric actuator(58) and the high frequency vibration is created by the high frequency interference of control voltage or control current of the actuator.

Description

How the engine works, in particular the direct injection engine, computer program, control and / or control unit {METHOD FOR OPERATING AN ENGINE, IN PARTICULAR A DIRECT INJECTION ENGINE, COMPUTER PROGRAM, AND CONTROL AND / OR REGULATION UNIT}

The present invention relates to a method of operating an engine, in particular a direct injection engine, wherein fuel is supplied to and injected from at least one injector into at least one combustion chamber.

Such a method is known from DE 199 45 813 A1. Here, an engine is described in which fuel is injected into the combustion chamber of the engine directly from the injection valve. By misfire detection, the deposition in the combustion chamber or on the injection valve is estimated. Such deposits can lead to deterioration of fuel sparks and thereby deterioration and misfire of combustion, especially in stratified operation of the engine. In order to remove the deposits detected on the injection valve, it is proposed to generate knocking combustion and / or to introduce a cleaning fluid into the combustion chamber of the engine.

It is an object of the present invention to improve the method of the aforementioned type so that contamination on the injection device can be more simply and reliably removed or prevented from the outset. Here, the operation of the engine should not deteriorate.

This object is solved in the method of the type mentioned initially, in which at least one region adjacent the at least one outlet opening of the fuel injection device is subjected to vibration at high frequency for at least a certain time.

The method according to the invention has the advantage that deposits, for example coke, which may be present in the region of the exit openings of the injection device can be reliably removed. This ensures that the outlet openings always have a maximum given cross section. Here, the operation of the engine is generally maintained unaffected, because no knocking combustion occurs and no other material is introduced into the combustion chamber. This makes for example good exhaust gas quality and engine quietness.

Since the operation of the engine continues to remain unaffected, the device according to the invention can be carried out preventively, so that no deposits can be maintained on the injection device.

Other preferred embodiments of the invention are given in the dependent claims.

In the first embodiment, it is proposed that the valve element of the fuel injection device is subjected to high frequency vibration for at least a certain time. The vibration of the valve element is transmitted onto the fuel present between the valve element and the outlet opening and from there onto the region surrounding the outlet openings, which facilitates the removal of deposits in the region of the outlet opening. This embodiment of the method according to the invention operates with high efficiency. In addition, this is realized simply because the valve element is a highly dynamic component and technically relatively simple to receive high frequency vibrations.

Here, it is proposed that the valve element is subjected to high frequency vibration in the range of at least one opening step. Thus, cleaning of the outlet openings can be made during normal operation of the engine, which allows for frequent cleaning of the outlet openings.

Preferably, the valve element is operated by a piezoelectric actuator and the high frequency vibration is generated by the high frequency interference of the control voltage or control current of the piezoelectric actuator. Piezoelectric actuators are very dynamic drive elements for valve elements, whereby high frequency vibrations are very active and can be generated appropriately.

In another embodiment, the torques and / or lambda values of the individual cylinders in a multicylinder engine are determined and compared to detect possible contamination of at least one outlet opening of the injection device, and then at least of at least one cylinder. Once the maximum permissible deviation of torque and / or lambda value from one other cylinder is reached and / or exceeded, at least one region adjacent to at least one outlet opening of the fuel injection device is subjected to high frequency vibration for at least some time.

In this embodiment of the method according to the invention, it can also be detected when cleaning of the outlet openings of the injection valve or the area adjacent to the outlet openings is required. This is usually based on the concept that not all of the outlet openings of all the injection valves are changed, narrowed or blocked in the same way. If all of the outlet openings of the injector of one cylinder have a different cross-sectional area than the outlet openings of the injector of another cylinder, this leads to different air-fuel mixture ratios and / or different combustion in the individual cylinders, which are different cylinders of one cylinder. Deviation from the torque and / or lambda value from the In this method according to the invention, the condition of the outlet openings of the injection device is monitored in a simple manner and in a way that does not require additional components and optionally a cleaning process is initiated. Correspondingly operating engines can also always run optimally without user assistance.

In this embodiment, the torques and / or lambda values of the individual cylinders of the outlet openings of the injection valve are normally not after It is determined and compared to detect if there is any possible contamination, and then if the maximum permissible deviation of torque and / or lambda values from at least one other cylinder of at least one cylinder is reached and / or exceeded, the fuel It is proposed that at least one region adjacent the at least one outlet opening of the injection device is subjected to high frequency vibration for at least some time.

In this embodiment according to the invention, it is checked whether the washing was effective after the washing process. If the time at which the high frequency vibration was generated was not sufficient to free the exit openings, the remaining cleaning process is usually started automatically without the help of the user. By this method according to the invention, it is better ensured that the outlet openings of the injection valves are essentially always optimally free in cross section.

In an embodiment for this purpose, it is proposed that an error report is generated and / or stored in storage once the maximum number of executions of the method of the above scheme is reached and / or exceeded. If it is detected that after a certain number of runs the cleaning procedure has not sufficiently improved the mixer quality in the combustion chamber, it is derived that the cause for the wrong mixer composition in the combustion chamber is not in contamination of the outlet openings of the fuel injection device. This is signaled to the user of the engine and / or corresponding error report is stored in storage for later service. In this method according to the invention it is ensured that the washing process is performed unnecessarily. If the mixer quality is improved after the cleaning process, this information can also be stored in the error store. The workshop maintains information on how often the fuel injectors are clogged.

Another method of the present invention works particularly well if the high frequency vibration has a frequency within the ultrasonic range. Thereby, a relatively large energy can be delivered which also enables the removal of severe contamination. Here, no audible noise phenomenon occurs.

The invention also relates to a computer program suitable for executing the method when executed on a computer. It is particularly preferable here that the computer program is stored on a storage, in particular flash memory.

Moreover, the invention relates to a control and / or adjustment unit for controlling and / or adjusting at least one function of the engine. In such a control and / or adjustment unit, it is particularly preferred to include a storage in which a computer program of this type is stored.

In the following, particularly preferred embodiments of the present invention are described in more detail with reference to the accompanying drawings.

1 illustrates the principle of an engine having a fuel system and a plurality of fuel injection devices;

FIG. 2 is a partial cross-sectional view of one of the fuel injectors of FIG.

FIG. 3 is a diagram showing the time course of the control of the actuator of the fuel injection device of FIG.

4 is a diagram in which the stroke of the valve element of the fuel injection device of FIG. 2 is plotted against time;

5 is a diagram showing the amount of fuel injected during the opening phase of the fuel injection device of FIG.

<Explanation of symbols for the main parts of the drawings>

10: engine

30: fuel injection valve

44: valve element

50: outlet opening

84: high frequency vibration

In Fig. 1, the engine is shown in dashed lines and indicated by reference numeral 10. The ancillary fuel system is indicated at 12.

The fuel system 12 includes a fuel tank 14, from which the electric fuel pump 16 supplies fuel via a filter 18. By the low pressure fuel conduit 20, the fuel reaches the high pressure fuel pump 22. The pressure in the low pressure fuel conduit 20 is regulated by a pressure regulating valve 24.

The high pressure fuel pump 22 supplies fuel into the fuel accumulation conduit 26 under very high pressure. This is commonly called "rail". Here, the fuel is stored under very high pressure. A fuel amount control valve 28 controls the amount of fuel supplied to the fuel accumulation conduit 26.

On the fuel accumulation conduit 26, a plurality of fuel injection valves 30a, 30b, 30c are connected. The specific structure thereof is described in detail below. The fuel injection valves 30a, 30b, 30c directly inject fuel into the combustion chambers 32a, 32b, 32c of the cylinders 33a, 33b, 33c of the engine 10. The fuel injection valves 30a, 30b, 30c are driven by the control and regulation unit 34.

The specific structure of the fuel injection valves 30a, 30b, 30c can be seen from FIG. 2 in which the fuel injection valve 30 is illustratively shown. Another possible detailed structure of the fuel injection valve is described in DE 198 44 837 A1, the contents of which are referred to herein.

Each fuel injection valve 30 includes a valve body 36 held axially with respect to the valve holder 40 by a tension nut 38. The valve body 36 protrudes into the combustion chamber 32 of the engine 10 by its free end with reduced cross section. In the hole 42 of the valve body 36, the piston type valve element 44 is guided axially movable in a known manner. The combustion chamber side spherical end face of the valve element forms a valve sealing face 46. This acts on the combustion chamber side closed end of the hole 42 with the valve seat surface 48 formed into a corresponding hollow sphere. A plurality of outlet openings 50 peripherally distributed in the wall of the valve body 36 are connected onto the valve seat surface 48 in the flow direction of the injected fuel.

The valve body 36 includes a pressure chamber 52 formed by enlarging the cross section of the hole 42, and the inlet channel 54 passing through the valve body 36 and the valve retainer 40 into the pressure chamber is connected. do. The inlet channel is connected to the fuel accumulation conduit 26 by a high pressure connection 56.

In order to operate the valve element 44 whose pressure is adjusted by the cross-sectional shape, there is a piezoelectric actuator 58 in the valve holder 40, which is formed of a plurality of disks arranged side by side in the axial direction and its axial direction. The length is reduced by applying the operating voltage.

The piezo actuator 58 is fixedly connected to the valve element 44 on its end facing the valve body 36. On the other end of the piezoelectric actuator, there is a regulating piston 60 with a smaller cross section opposite to the piezoelectric actuator 58. One end of the adjustment piston extends in the axial direction and lies on the end face 62 of the piezoelectric actuator 58 and its free end protrudes into the adjustment chamber 64. The end facing away from the valve element 44 of the piezo actuator 58 defines a spring chamber 66 through which the adjustment piston 60 passes, and within the spring chamber there is a valve spring 68 which acts as a pressure spring. The valve spring is sandwiched between the end face 62 of the piezoelectric actuator 58 and the wall of the spring chamber to press the valve element 44 in the closing direction through the piezoelectric actuator 58.

The operation of the piezoelectric actuator 58 is through an electrical supply line 70 which is connected to the control and regulation unit 34.

Clamping device 72 on the upper end of piezoelectric actuator 58 opposite valve element 44 for precisely defined axial adjustment movement of piezoelectric actuator 58 and thus precise opening stroke movement of valve element 44. ) Is placed. By this clamping device 72, the piezoelectric actuator 58 is fixed in its position on its upper end relative to the valve holder 40 during the spraying step. Here, the clapping device 72 is formed by a ring 74 arranged coaxially with respect to the piezoelectric actuator 58, and the frictional coupling type on the peripheral surface of the piezoelectric actuator 58 by reducing the inner diameter upon receiving the operating voltage. Abuts.

The current supply is made via the electrical supply line 76 and also controlled by the control and regulation unit 34. In normal operation, current flows in the clamping device 72 so that the piezoelectric actuator 58 is fixed in its position. During the spray pause, the clapping device 72 can be released to compensate for the length change with the temperature and pressure of the piezoelectric actuator 58 and to prevent the deterioration of the precise open stroke movement caused thereby.

The engine 10 and the fuel injection valve 30 formed in accordance with FIG. 2 are operated in accordance with the method stored in the control and regulation unit 34 as a computer program. The method is now described with reference to FIGS.

When the engine 10 is started, the clamping device 72 is driven by the control and regulating unit 34 so that the piezoelectric actuator 58 is fixed to the valve holder 40 by the clamping device. Thus, the valve spring 68 used to cause the valve sealing surface 46 to move relative to the valve seat surface 48 does not work.

In order to initiate the open stroke movement of the valve element 44, a current flows into the piezoelectric actuator 58 by the control and regulating unit 34. Next, a remarkably high current is applied on the piezoelectric actuator 58. This is indicated by reference numeral 78 in FIG. This high current is used to achieve a very short switching time of the piezo actuator 58. This is realized by operating voltages of up to 90 volts via capacitive electronics.

As current flows through the piezoelectric actuator 58, the piezoelectric actuator is reduced. Since the valve element 44 is fixedly attached on the lower end of the piezoelectric actuator 58, the valve element 44 is pulled upward in FIG. 2, so that the valve sealing surface 46 is removed from the valve seat surface 48. Is lifted. This process is indicated by reference numeral 80 in FIG.

As soon as the valve element 44 reaches its open end position, the current flow of the piezoelectric actuator 58 is repeatedly interrupted in the form of a pulse. This is indicated by reference numeral 82 in FIG. By the interruption in the form of such a high frequency pulse of the control current of the piezoelectric actuator 58, the piezoelectric actuator generates high frequency vibration indicated by 84 in FIG. The pulse frequency of the current flow 82 is selected such that the vibration frequency acting on the piezoelectric actuator 58 and the valve element 44 connected thereto is located in the ultrasonic region.

The stroke of the valve element 44 can be optimized by the vibrational frequency of the valve element 44 being in the region of the resonant frequency of the system consisting of the valve element 44 and the piezoelectric actuator 58. As can be seen in FIG. 3, even though the current flow of the piezoelectric actuator 58 is zero between each current pulse, the valve element 44 is in its open position as a whole rather than closed by the inertia of the piezoelectric actuator 58. Only vibrate.

Since the usable cross-sectional area between the valve face 46 and the valve seat face 48 during the opening time of the valve element 44 based on the vibrating movement of the valve element 44 is slightly smaller than without this vibrating movement, The valve opening time may be slightly longer to inject the same amount of fuel through the fuel injection valve 30. The end of the non-vibrating injection time of the valve element 44 is shown by dashed lines 86 in FIGS. 4 and 5. The end of the injection time with high frequency vibration of the valve element 44 is shown by the solid line 88. The injected fuel amount is shown by the horizontal line 90 in FIG. The trend of the amount of fuel injected from the fuel injection valve 30 into the combustion chamber 32 is linear as can be seen in FIG. If there is vibration interference on the valve element 44, the transition is slightly slower (89) in each case where no high frequency vibrations are acting on the valve element 44 (91).

The average current strength required for opening the valve element 44 is shown by dashed line 92 in FIG. As can be seen in FIG. 3, this is approximately half the level of current required without generating vibration of the valve element 44. Therefore, in order to keep the fuel injection valve 30 open, a small current as a whole is required.

When the desired amount of fuel is injected, the current flow of the piezoelectric actuator 58 is terminated by the control and regulating unit 34. This is indicated by reference numeral 94 in FIG. The corresponding closing motion of the valve element 44 with the valve sealing surface 46 close to the valve seat surface 48 until the valve sealing surface 46 abuts on the valve seat surface 48 is shown in FIG. 4. Reference numeral 96 is used. The maximum time used for generating vibration of the valve element 44 is indicated by reference numeral 98 in FIG. 4. The maximum time is slightly shorter than the opening time of the valve element 44 because it has to wait for the valve element to reach its open completion state for the valve element 44 to start opening. For this reason, delay in opening of the valve element 44 should be prevented.

By generating a high frequency vibration on the valve element 44, the fluid column between the valve sealing surface 46 and the valve seat surface 48 is also vibrated. This vibration is transmitted onto the area of the outlet opening 50. Generating vibration on the valve element 44 of the fuel injection valve 30 may be applied in two different ways. Such vibrations may occur at the time of injection of the fuel injection valve 30 on a regular basis to prevent deposits from forming generally in the region of the outlet openings 50 or within the outlet opening itself. Alternatively, it is also possible for vibrations to occur on the valve element 44 at longer periods of time such that deposits already present in or around the outlet openings 50 are removed. Here, it is possible to detect the presence of deposits in the following manners and methods.

In the engine 10, there is usually a so-called cylinder compensation device. This means that the torque difference of the individual cylinders 33a or 33b or 33c of the engine 10 can be detected based on different combustion in the combustion chamber 32a or 32b or 32c arranged in the cylinder. For example, if it is determined that the torque of the cylinder 33a deviates more than the allowable value from the torque of the cylinder 33b, this means that the cross section of the outlet openings 50 of the fuel injection valve 30a of the cylinder 33a is caused by deposits. It becomes narrower, resulting in less fuel reaching the corresponding combustion chamber 32a.

In this case, the valve element 44 of the corresponding fuel injection valve 30a is moved by the high frequency vibration described above by the control and regulating unit 34. This movement is made over time which includes a plurality of injections of the fuel injection valves 30a and 30b. After the end of this time, the movement of the valve element 44 subjected to the high frequency vibration is terminated, and the torques of the cylinders 33a and 33b are compared again.

If the deviation is in the permissible region, this means that deposits present in the region of the outlet openings 50 have been removed. Otherwise it means that not all of the deposit has been removed. From this, the valve element 44 of the fuel injection valves 30a and 30b again moves under high frequency vibration for a predetermined time including a plurality of injections. (Of course, each moves only during the opening phase of the fuel injection valve.) Next, the torques of the cylinders 33a, 33b are again compared to determine if the deviation of the torques is within an allowable limit. This process is repeated several times.

The number of runs is limited to the maximum value. Once the maximum is reached and / or exceeded, it can be derived that the deposit may not be removed by the high frequency vibration of the valve element 44 or there is another cause for the torque difference between the cylinders 33a, 33b. In such a case, an error report is generated by the control and adjustment unit 34 so that, for example, a warning light of the instrument panel of the vehicle in which the engine 10 is installed is lit. In addition, the error report can be registered into the error storage unit in the control and adjustment unit 34 and read out by, for example, the diagnostic apparatus at the time of service.

According to the present invention, contamination on the fuel injector can be reliably removed, and contamination of the fuel injector can be prevented.

Claims (11)

In a method of operating an engine, in particular a direct injection engine 10, in which fuel is supplied to and injected from at least one fuel injection device 30 into at least one combustion chamber 32. At least one region (44) adjacent the at least one outlet opening (50) of the fuel injection device (30) is subjected to high frequency vibrations (84) for at least some time. The method of claim 1, wherein the valve element (44) of the fuel injection device (30) is subjected to high frequency vibration (84) for at least a period of time. 3. Method according to claim 2, characterized in that the valve element (44) is subjected to high frequency vibrations (84) in at least one range (98) of at least one opening step. 4. The valve element (44) according to claim 2 or 3, wherein the valve element (44) is moved by a piezoelectric actuator (58) and the high frequency vibration (84) is generated by high frequency interference of the control voltage or control current of the piezoelectric actuator (58). How to feature. Torque and / or lambda values of the individual cylinders 33 in the multicylinder engine 10 may be contaminated in at least one outlet opening 50 of the fuel injection device 30. Is determined and compared, and then a maximum injection deviation of torque and / or lambda value from at least one other cylinder 33b of at least one cylinder 33a is reached and / or exceeded, then fuel injection At least one region (44) adjacent the at least one outlet opening (50) of the device (30) is subjected to high frequency vibrations (84) for at least some time. 6. A separate cylinder (33) as claimed in claim 5, in which at least one area (44) adjacent the outlet openings (50) of the fuel injection device (30) has normally received a high frequency vibration (84) for a period of time. Torques and / or lambda values are determined and compared to detect if any possible contamination of the outlet openings 50 of the injection valve 30 has been removed and then at least one of the at least one cylinder 33a. At least one region 44 adjacent the at least one outlet opening 50 of the fuel injection device 30 is reached and / or exceeded when the maximum allowable deviation of torque and / or lambda value from the other cylinder 33b is reached. Is subjected to high frequency vibrations (84) for at least a period of time. 7. A method according to claim 6, wherein if a maximum number of times of execution of the method according to claim 6 is reached and / or exceeded, an error report is generated and / or stored in storage. Method according to any one of the preceding claims, characterized in that the high frequency vibration (84) has a frequency in the ultrasonic region. A computer program adapted to, when executed on a computer, perform a method according to any one of the preceding claims. 10. A computer program according to claim 9, characterized in that it is stored on a storage, in particular flash memory. In the control and / or adjustment unit 34 for controlling and / or adjusting at least one function of the engine 10, A control and / or adjustment unit according to claim 9 or 10, comprising a storage unit in which another computer program is stored.