EP2681432B1 - Method for controlling an internal combustion engine - Google Patents

Description

The invention relates to a method for controlling an internal combustion engine according to the preamble of claim 1.

State of the art

Such a method for controlling an internal combustion engine is known from EP 1 767 769 A1 known. The internal combustion engine has at least one piston pivotally mounted on a crankshaft and is equipped with a common-rail injection system. The common rail injection system has a high pressure pump with a pump camshaft having at least one cam and at least one pump plunger cooperating with the pump camshaft via a roller tappet. The angular offset of the pump camshaft to the crankshaft is designed in terms of wear-minimized and operationally optimized operation of the internal combustion engine. The angular offset of the pump camshaft to the crankshaft is designed so that the order of the torque excitation of the pump camshaft is equal to the order of the torque excitation at least one camshaft of the engine and extinguish at least partially oscillations of the torque at the pump camshaft and oscillations of the torque at the camshaft. A defined angular offset of the pump camshaft to the crankshaft at the start and / or stop of the internal combustion engine is not taken into account here.

By the DE 197 21 841 A1 a method for controlling an internal combustion engine is known, in which the angular offset of the pump camshaft to the crankshaft of the internal combustion engine by an angle adjustment in dependence on operating parameters of the internal combustion engine such as load and speed can be variably adjusted. However, here too, no defined angular offset of the pump camshaft to the crankshaft during start and / or stop of the internal combustion engine is taken into account.

The invention has for its object to provide a method for controlling an internal combustion engine, with the particular during the start and / or stop of the engine, the wear behavior and performance of the high-pressure pump is improved.

Disclosure of the invention description

This object is achieved in that at a fixed angular position of the start and / or stop of the internal combustion engine takes place at a crankshaft angle, which is optimized for the operation of the high-pressure pump. In this case, the operation is optimized, for example, with regard to the occurring forces and / or the wear behavior and the start and / or stop of the internal combustion engine takes place at a crankshaft angle at which the at least one cam of the pump camshaft is in the range outside of an upper and lower dead center of the roller tappet , It should be noted that in the area of the top and bottom dead center, the risk of a ram in the high-pressure pump is greatest. According to the invention, these ranges, which are at -5 ° to + 5 °, 85 ° to 95 °, 175 ° to 185 ° and 265 ° to 275 ° (PNW), are avoided.

Thus, in a four-cylinder in-line engine, awkward rotational positions of the crankshaft are 51 ° ± 5 °, 141 ° ± 5 °, 231 ° ± 5 °, 321 ° ± 5 °, 411 ° ± 5 °, 501 ° ± 5 °, 591 ° ± 5 ° and 681 ± 5 ° (KW). In a V-type six-cylinder internal combustion engine, unfavorable crankshaft angular positions are 51 ° ± 5 °, 141 ° ± 5 °, 231 ° ± 5 °, 321 ± 5 °, 411 ° ± 5 °, 501 ± 5 °, 591 ° ± 5 ° and 681 ± 5 ° (KW).

In a further development of an internal combustion engine electronics stops at a stop command, the crankshaft at a predetermined crankshaft angle, which avoids the previously specified areas. This stopping process can take place in that, depending on operating parameters of the internal combustion engine and the high-pressure pump, the stop command of, for example, an automatic start-stop system of the internal combustion engine is converted at a crankshaft angle, of which the internal combustion engine electronics know that the internal combustion engine has reached a specific angle of rotation after reaching this crankshaft angle continue to turn and then come to a halt. Optionally, an auxiliary device, such as a starter for targeted braking of the crankshaft can be used by the starter is used in this operating condition as a brake.

In a further development of the invention, the engine electronics by means of an auxiliary device at a stop command and / or start command rotates the crankshaft to a predetermined crankshaft angle, which also avoids the previously specified areas. If the internal combustion engine runs so that the crankshaft and thus the pump camshaft is in an unfavorable rotational position, the crankshaft is rotated further until a favorable angular position of the pump camshaft is reached. This can in turn be done for example by the controlled use of the starter during the stop process or during the subsequent startup of the internal combustion engine.

Further advantageous embodiments of the invention are shown in the drawing, are described in more detail in the embodiments illustrated in the figures of the invention.

Brief description of the drawings

• Fig. 1 in schematischer Darstellung einen Schnitt durch eine als Einstempelpumpe ausgebildete Hochdruckpumpe,
• Fig. 2 in Diagrammform nachteilige Stopppositionen für eine vierzylindrige Brennkraftmaschine,
• Fig. 3 eine als Zweistempelpumpe ausgebildete Hochdruckpumpe und
• Fig. 4 in Diagrammform nachteilige Stopp-Positionen für eine sechszylindrige V-Brennkraftmaschine.

Show it:

• Fig. 1 a schematic representation of a section through a high-pressure pump designed as Einempelpumpe,
• Fig. 2 in diagram form disadvantageous stop positions for a four-cylinder internal combustion engine,
• Fig. 3 designed as a two-stamp pump high-pressure pump and
• Fig. 4 in diagram form disadvantageous stop positions for a six-cylinder V-type internal combustion engine.

Embodiments of the invention

The high-pressure pump 1 according to Fig. 1 is designed as a stamped pump and has a pump housing 2 by a pump camshaft 3 is rotatably mounted. The pump camshaft 3 has two opposing cams 4. On the cam track thus formed runs a roller tappet 5 with a roller 6 from. The roller 6 is rotatably mounted in a roller shoe of the roller tappet 5 and converts the rotational movement of the pump camshaft 3 in a translational up and down movement of the roller tappet 5. With the roller tappet 5, a pump plunger 7 cooperates, of a plunger 8 against the roller tappet 5 is pressed. The pump plunger 7 is guided in a cylinder and cooperates with a working space, is introduced into the controlled fuel. This introduced into the working space fuel is conveyed in a pumping movement of the pump plunger 7 in a high-pressure accumulator, from which the fuel stored there under a pressure of up to about 3,000 bar fuel injectors is selectively removed and injected into associated combustion chambers of the internal combustion engine.

In the Fig. 1 shown high pressure pump 1 is designed for a four-cylinder engine and is driven with a gear ratio i = 1 of the crankshaft of the engine. In the illustrated embodiment, the pump camshaft 3 is at the rotational angle 0 ° PNW with respect to the roller tappet 5 and the roller 6, wherein the rotation angle 90 °, 180 ° and 270 ° (PNW) in Fig. 1 are additionally entered. Between the pump camshaft 3 and the crankshaft of the internal combustion engine, an angular offset of 39 ° is provided in the form that the high-pressure pump always promotes 39 ° before the engine cylinder TDC and therefore at the engine cylinder TDC always 39 ° after the internal combustion engine Cylinder OT stands. The internal combustion engine is turned off according to the invention that in Fig. 1 shown rotational position (and below specified rotational position) of the pump camshaft 1 is not taken. These are the ranges -5 ° to + 5 °, 85 ° to 95 °, 175 ° to 185 ° and 265 ° to 275 ° (PNW).

For the internal combustion engine, thus resulting in the crankshaft disadvantageous parking positions, in Fig. 2 are shown or reproduced. The lower degree scale shows the pump camshaft angle PNW, while the crankshaft angle KW is entered on the upper degree scale. The angular offset of 39 ° between the crankshaft and the pump camshaft 3 results in the illustrated offset between the angular positions of the pump camshaft and the crankshaft. Corresponding to the previous explanations, this results in unfavorable engine cranking angles at a crank angle of 51 ° ± 5 °, 141 ° ± 5 °, 231 ° ± 5 °, 321 ± 5 °, 411 ± 5 °, 501 ± 5 ° and 681 ± 5 ° (KW).

In the Fig. 3 shown high-pressure pump 1 is designed as a two-stamp pump and therefore has two roller tappet 5 and two pump plunger 7, which cooperate with the pump camshaft 3. The pump camshaft 3 also has two opposed cams 4 in this embodiment. This high-pressure pump 1 is designed for mounting on a six-cylinder V-type internal combustion engine and the pump camshaft 3 is driven with a transmission ratio i = 3/4 of the crankshaft of the internal combustion engine. 2 revolutions of the crankshaft thus correspond to 1.5 revolutions of the pump camshaft. The angular offset of the pump camshaft with respect to the crankshaft is 16.36 °, the pump with respect to the pump camshaft angle always promotes this amount after the engine cylinder TDC and therefore at the internal combustion engine cylinder TDC always 16.36 ° before the internal combustion engine Cylinder OT stands.

For the internal combustion engine, thus resulting in the crankshaft disadvantageous parking positions, in Fig. 4 are shown or reproduced. The lower scale shows as in Fig. 2 The pump camshaft angle PNW, while registered on the upper degree scale of the crankshaft angle KW. The angular offset of 16.36 ° between the crankshaft and the pump camshaft 3 results in the illustrated offset between the angular positions of the pump camshaft and the crankshaft. Corresponding to the previous explanations unfavorable setting off angles of the crankshaft result at 21.7 ° ± 7 °, 141.7 ° ± 7 °, 261.7 ° ± 7 °, 381.7 ° ± 7 °, 501.7 ° ± 7 ° and 621.7 ° ± 7 ° (KW). Related to the pump camshaft 3, the tolerance band is identical to the in FIG. 1 illustrated high-pressure pump 1, but since there is a transmission ratio of i = 3/4 of the crankshaft to the pump camshaft 3, here increases the tolerance band to approximately ± 7 °.

Claims (3)

1. Method for controlling an internal combustion engine with at least one piston fastened in an articulated manner to a crankshaft, and with a common-rail injection system, having a high-pressure pump (1) with a pump camshaft (3) having at least one cam (4), and at least one pump plunger (7) interacting with the pump camshaft (3) via a roller tappet (5), wherein the angular offset of the pump camshaft (3) with respect to the crankshaft is designed in respect of a wear-minimized and operationally optimized operation of the internal combustion engine, characterized in that, at a defined angular offset, the starting and/or the stopping of the internal combustion engine take/takes place at a crankshaft angle which is optimized for the operation of the injection system, and in that the starting and/or the stopping take/takes place at a crankshaft angle at which the at least one cam (4) of the pump camshaft (3) is in the region outside an upper and lower dead centre of the roller tappet (5).
2. Method according to Claim 1,
   characterized in that, in the event of a stopping command, an electronic control system of the internal combustion engine stops the crankshaft at a predetermined crankshaft angle.
3. Method according to Claim 1 or 2,
   characterized in that, in the event of a stopping command and/or starting command, the electronic control system of the internal combustion engine rotates the crankshaft further to a predetermined crankshaft angle by means of an auxiliary device.

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