EP3020946A1 - Method for detecting the pumping orientation of a high-pressure fuel pump - Google Patents

Abstract

A method for detecting the pump orientation of a high-pressure fuel pump with drivable intake valve of an internal combustion engine with a common rail injection system for fuel injection, which is closed from a rail pressure signal to a pump position with respect to the cam position of the internal combustion engine.

Description

The invention relates to a method for detecting the pump orientation of a high-pressure fuel pump with controllable suction valve according to the preamble of claim 1.

The subject matter of the present invention is also a computer program which is set up to carry out each step of the method according to the invention as well as an electronic storage medium on which the computer program is stored. Finally, the invention relates to an electronic control device which comprises an electronic storage medium.

State of the art

In internal combustion engines usually an inductive sensor is provided, which scans the teeth on the starter ring gear and determines therefrom a speed value. In addition, it is provided that the top dead center of at least one cylinder is marked by means of a marking. For this purpose, it is provided in particular that a tooth is omitted or a tooth is highlighted accordingly. This can be done by a tooth deviating from the other teeth in a certain way. For example, a tooth may be made of a different material.

Such an arrangement has the disadvantage that when assembling the internal combustion engine, in particular when mounting the starter ring gear and the inductive generator must be worked very carefully. Dodges the time in which the top dead center mark occurs from the actual occurrence of the top dead center, this leads to inaccurate control of the internal combustion engine. Such a deviation may, among other things, result in increased exhaust emission.

Disclosure of the invention Advantages of the invention

The inventive method for detecting the pump orientation of a high-pressure fuel pump with in particular electrically controllable intake valve of an internal combustion engine with a common rail injection system for fuel injection, in which is closed from a rail pressure signal to a pump position with respect to a cam position of the internal combustion engine, has the advantage that an automatic detection of the pump position is determined and this eliminates the effort to obstruct the pump with a specific orientation to the internal combustion engine, which takes place during assembly of the internal combustion engine. In addition, very advantageous for detecting the pump orientation no additional sensor required, which would cause additional costs. By "detecting the pump position", the present application understands the detection of the position of a pump toggle with respect to, for example, the top dead center (TDC) of the internal combustion engine.

The measures listed in the dependent claims advantageous refinements and embodiments of the method specified in claim 1 are possible.

Thus, an advantageous embodiment of the method, which allows the detection of a top dead center, that during a start of the internal combustion engine, the controllable suction valve is permanently opened and that the time of Raildruckanstiegs is detected and corrected by a predetermined value, the time offset between Control start and pressure detection on the rail pressure sensor compensates.

Another embodiment of the method, which allows to detect a top dead center, provides that during a start of the internal combustion engine or in overrun, in which the internal combustion engine rotates without injection, the rail pressure is detected and that then, when the rail pressure increases, it it is concluded that a selected top dead center of the pump is in a rising cam flank and that the top dead center is moved in the direction of lower injection quantity until the rail pressure remains constant.

A further advantageous variant of the method according to the invention seeks a rising edge. This provides that during the start of the internal combustion engine or during the overrun operation, in which the internal combustion engine rotates without injection, the rail pressure is detected and, if the rail pressure remains constant, it is concluded that a selected top dead center lies in a falling cam flank and the high-pressure fuel pump delivers no fuel and that the top dead center is moved so long in the direction of larger injection amount until the pressure rises.

Advantageously, the detected rail pressure is corrected by a transit time of a pressure wave, so as to compensate for negative influences caused by the pressure wave.

A further variant of the method according to the invention provides that during a start of the internal combustion engine, the controllable intake valve, at least once more than delivery strokes exist, is controlled, wherein the control is offset by a geometric cam offset and that when, after a drive pulse, a pressure increase in Rail takes place, is closed on a rising edge, which is used as a reference for the control.

The computer program according to the invention is set up to carry out each step of the method, in particular if it runs on a computing device or a control device. It allows the implementation of the inventive method on an electronic control unit, without having to make structural changes to this. For this purpose, the electronic storage medium is provided on which the computer program according to the invention is stored. By loading the computer program according to the invention onto an electronic control unit, the electronic control unit according to the invention is obtained, which is set up to carry out the method according to the invention.

Brief description of the drawings

Embodiments of the invention are illustrated in the drawings and explained in more detail in the following description.

• Fig. 1 ein Ablaufdiagramm einer Ausführungsform des erfindungsgemäßen Verfahrens zur Erkennung des unteren Totpunktes.
• Fig. 2 ein Ablaufdiagramm einer weiteren Ausführungsform des erfindungsgemäßen Verfahrens zur Erkennung des oberen Totpunktes und
• Fig. 3 ein Ablaufdiagramm einer wiederum anderen Ausführungsform des erfindungsgemäßen Verfahrens zum Suchen einer ansteigenden Flanke.

Show it:

• Fig. 1 a flow diagram of an embodiment of the inventive method for detecting the bottom dead center.
• Fig. 2 a flowchart of another embodiment of the inventive method for detecting top dead center and
• Fig. 3 a flowchart of yet another embodiment of the method according to the invention for searching a rising edge.

Embodiments of the invention

The method according to the invention described below is used in high-pressure diesel pumps, in which the fuel metering is realized via an electrically actuated suction valve. The timing of the control is decisive for the volume control. For this timing of the control, the camshaft position must be known to allow timely driving. The variants of the method according to the invention described below make it possible to determine the cam position on the internal combustion engine on the basis of the rail pressure signal. The advantage of this automatic detection is that the effort during assembly eliminates the need to install the pump with a specific orientation. Pump orientation detection does not require an additional sensor, so there are no additional costs.

In Fig. 1 a first variant of the method according to the invention is shown. During an engine start in a step 100, a suction valve is permanently energized, whereby the maximum delivery rate is reached, step 110, while another suction valve is deactivated, step 120.

In a step 130, the rail pressure is detected. In a step 140, the time of a rail pressure rise is detected and corrected by a predetermined value, which compensates the time offset between actuation start and pressure detection on a rail pressure sensor. This parameter, which is determined beforehand, depends on the system design, the motor speed and the pumps: motor translation. This method allows the detection of the top dead center of the camshaft and thus the position of the pump, which is clearly assigned to the cam position.

In Fig. 2 a further embodiment of the method is shown, which allows the detection of the top dead center. Before detection, the top dead center of the pump is set arbitrarily. Basically, the angle at the beginning of the process does not matter and can therefore be set arbitrarily, since when not recognizing a pressure increase, the angle is varied. In practice, however, a starting point should be specified. This can be, for example, 0 ° crank angle or also the last detected and stored value of the mounting angle. Furthermore, it may happen that the pump is removed and installed during the life of the engine. In this case, although the position of the pump prior to removal is known, but it is no longer after installation. For the detection then the last known angle can be used. During the start of the internal combustion engine or in the thrust, during which the internal combustion engine rotates without injection, the rail pressure is detected. In step 210, the start of the internal combustion engine is shown. Step 220 designates the activation of the intake valve 1 at 0 ° crankshaft angle. Step 230 designates the activation of the suction valve 2 at a crankshaft angle of 180 °. The detection can with a Pump element or with multiple pump elements, as long as the control is offset by the geometric cam offset, for example, two elements with two cams by 90 °. The geometric distance relative to the rotation of the camshaft is always the same. If a pump with two high-pressure elements and two cams is used, this means that each pump element is actuated twice in one revolution. For example, at 0 ° pump element 1, at 90 ° pump element 2, at 180 ° pump element 1, at 270 ° pump element 2. If now trying to control the pump element 1 at 17 ° and no pressure increase is found, it can be concluded that next time must be addressed. For example, assuming that it is corrected by 5 °, then the second pump element must be driven at 17 ° + 90 ° - 5 ° = 102 ° and so on. The next control in a previously described pump element would then be a control at 17 ° + 180 ° - 5 ° = 192 ° .Es two cases are distinguished, which in Fig. 2 are shown side by side. The process shown on the right describes the case in which the rail pressure increases, which is detected in step 241. In this case, the selected top dead center lies in the rising cam flank and the pump delivers fuel. The top dead center is shifted in the direction of less injection quantity (step 242) until the rail pressure remains constant, ie no further increase in rail pressure is recorded (step 243).

The left column indicates the second case where the rail pressure remains constant. If the rail pressure remains constant, so no Raildruckanstieg is determined, step 251, is the selected top dead center in the falling cam edge and the pump does not deliver fuel. Now, the top dead center is shifted toward the larger injection amount, step 252, until the pressure rises, which is detected in step 253. In a step 260, the time found is corrected by the transit time of the pressure wave. It should be emphasized at this point that the two columns, steps 241, 242, 243 and steps 251, 252, 253, which are shown side by side, represent two different cases that exist differently and do not run side by side. The representation side by side was chosen only for the sake of simplicity.

In Fig. 3 If a further embodiment of the method is shown, during an engine start, step 310, at least one intake valve is energized several times, at least three times per 180 ° crankshaft angle. The detection can be carried out with one pump element or with several pump elements as long as the control is offset by the geometric cam offset, eg two elements with two cams each by 90 °. In step 320, the control of a suction valve 1 is shown at 0 ° camshaft angle and in step 330, the control of a suction valve 2 at 180 ° camshaft angle. If a pressure increase occurs after such a drive pulse, which is detected in step 340, the rising edge is found and used as a reference for the drive, step 350. Once the engine is idling, as determined in step 360, the rail pressure regulator becomes allows the pump delivery to be adjusted freely, without upper and lower limits, step 370. When the setpoint pressure, step 380, is reached, the pump attachment is corrected by means of the regulator output and pilot control, step 385, and the control returns to normal operation, step 390. The method can be implemented in a control unit of an internal combustion engine as a computer program. The computer program can be stored on an electronic storage medium which can be read in by the control unit.

Claims (9)

A method for detecting the pump orientation of a high-pressure fuel pump with drivable intake valve of an internal combustion engine with a common rail injection system for fuel injection, which is closed from a rail pressure signal to a pump position with respect to the cam position of the internal combustion engine. A method according to claim 1, characterized in that during a start of the internal combustion engine, the controllable suction valve is driven to open permanently and that the time of Raildruckanstiegs is detected and corrected by a predetermined value, which compensates for the time offset between the actuation start and pressure detection on the rail pressure sensor. A method according to claim 1, characterized in that during a start of the internal combustion engine or in overrun operation, in which the internal combustion engine rotates without injection, the rail pressure is detected and that, when the rail pressure increases, it is concluded that a selected upper dead center of the Pump is in a rising cam edge and that the top dead center is shifted so long in the direction of lower injection quantity until the rail pressure remains constant. A method according to claim 1, characterized in that during startup of the internal combustion engine or in overrun mode during which the internal combustion engine rotates without injection, the rail pressure is detected, and if the rail pressure remains constant, it is concluded that a selected top dead center in a falling Cam flank is located and the high-pressure fuel pump promotes no fuel and that the Top dead center is moved in the direction of larger injection quantity until the pressure rises. A method according to claim 3 or 4, characterized in that the detected rail pressure is corrected by a transit time of a pressure wave. A method according to claim 1, characterized in that during a start of the internal combustion engine, the controllable intake valve, at least once more than delivery strokes exist, is controlled, wherein the control is offset by a geometric cam offset and that when, after a drive pulse, a pressure increase in the rail is closed on a rising edge, which is used as a reference for the control. A computer program arranged to perform each step of the method of any of claims 1 to 6. An electronic storage medium on which a computer program according to claim 7 is stored. Electronic control device, which is set up to operate an internal combustion engine by means of a method according to one of claims 1 to 6.

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