JP6402566B2 - Control device for internal combustion engine - Google Patents

Description

  The present invention relates to a control device for an internal combustion engine having a variable compression ratio mechanism.

  A multi-link type piston crank mechanism has been widely used in which a piston and a crank pin of a crankshaft are linked by a plurality of links, and one of the plurality of links and a control shaft disposed below the crankshaft are linked by a control link. Are known.

  For example, in Patent Documents 1 and 2, in such a multi-link type piston crank mechanism, the lower side of the end portion of the shaft side of the control link is covered with a baffle cup and attached to the control eccentric shaft portion of the control shaft so as to be swingable. A configuration is disclosed in which the shaft side end portion of the control link is not interfered with engine oil in the oil pan.

JP 2011-241895 A JP 2011-241796 A

  The oil amount of the engine oil is managed so as to be within an allowable range, but the oil amount may increase even within the allowable range. In that case, the oil level in the oil pan rises relatively, and the control link may interfere with the engine oil and the friction may increase.

  Therefore, the present invention provides a lower link rotatably connected to a crankpin of a crankshaft, an upper link connecting the lower link and the piston, a control shaft disposed below the crankshaft, A variable compression ratio mechanism having a control link for connecting the eccentric shaft portion of the control shaft and the lower link, and capable of continuously changing the compression ratio of the internal combustion engine according to the rotational position of the control shaft. The variable compression ratio mechanism includes a cylinder block and an oil pan attached to the lower surface of the cylinder block. If you have an oil amount sensor to detect and the oil amount in the oil pan is more than a predetermined amount, Is characterized in that serial eccentric shaft rotates the control shaft so as to be positioned above.

  According to the present invention, even when the amount of engine oil is large, the engine oil in the oil pan is less likely to interfere with the control link, and an increase in control link friction due to the engine oil can be suppressed. .

BRIEF DESCRIPTION OF THE DRAWINGS Explanatory drawing which showed typically the control apparatus of the internal combustion engine which concerns on this invention. Explanatory drawing which showed typically the positional relationship of the eccentric shaft part of a control shaft at the time of a high compression ratio and a low compression ratio. The flowchart which shows an example of compression ratio control. Oil level correction value calculation map. Reference compression ratio calculation map.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is an explanatory view schematically showing a control device for an internal combustion engine according to the present invention.

  The internal combustion engine 10 is mounted on a vehicle such as an automobile, for example, and the engine compression ratio can be changed by changing the top dead center position of the piston 13 that reciprocates in the cylinder 12 of the cylinder block 11. A variable compression ratio mechanism 14 is provided.

  The variable compression ratio mechanism 14 uses a multi-link type piston crank mechanism in which the piston 13 and the crankpin 16 of the crankshaft 15 are linked by a plurality of links. The variable compression ratio mechanism 14 is rotatably mounted on the crankpin 16. A link 17, an upper link 18 for connecting the lower link 17 and the piston 13, a control shaft 19 provided with an eccentric shaft portion 20, a control link 21 for connecting the eccentric shaft portion 20 and the lower link 17, have.

  The crankshaft 15 is rotatably supported by the cylinder block 11 by the first bearing bracket 22. The crankshaft 15 is arranged below the piston 13 as shown in FIG. Here, “below the piston 13” means “below” in a direction along the engine vertical direction. The “engine up-down direction” is a direction along the cylinder center axis L (see FIG. 1) in a series internal combustion engine, and a direction along a bank center line that divides the bank angle into two in a V-type internal combustion engine. The direction along the cylinder center axis L is the reciprocating direction of the piston.

  The lower link 17 is located below the piston 13, and the other end of the upper link 18 and the other end of the control link 21 are rotatably connected to both sides of the crankpin bearing portion 17a. . That is, the lower link 17 has an upper link 18 rotatably connected to one end side, a control link 21 rotatably connected to the other end side, and a connection portion between the upper link 18 and a control link 21. The crankpin bearing portion 17a is located between the two. The crank pin 16 is rotatably connected to the crank pin bearing portion 17a.

  One end of the upper link 18 is rotatably connected to the piston pin 23, and the other end is rotatably connected to one end side of the lower link 17 by a first connection pin 24.

  The control link 21 restricts the movement of the lower link 17. One end of the control link 21 is rotatably connected to the eccentric shaft portion 20 of the control shaft 19, and the other end is connected to the other end of the lower link 17 by the second connecting pin 25. It is rotatably connected to the side.

Control shaft 19 is positioned below the crankshaft 15, disposed parallel to the crankshaft 15, and is rotatably supported by the cylinder block 11. Specifically, the control shaft 19 is rotatably supported between the first bearing bracket 22 and the second bearing bracket 26. The eccentric shaft portion 20 provided on the control shaft 19 is eccentric with respect to the rotation center of the control shaft 19.

  And this control shaft 19 is rotationally driven by the actuator 28 which consists of an electric motor via the gear mechanism 27, and the rotation position is controlled. The actuator 28 is controlled based on a command from the control unit 29. Note that the control shaft 19 may be rotationally driven by a hydraulic actuator.

  By changing the rotational position of the control shaft 19 by the actuator 28, the position of the eccentric shaft portion 20 that becomes the swing fulcrum of the control link 21 changes. As a result, the posture of the lower link 17 by the control link 21 is changed, and the compression ratio is continuously increased with the piston motion (stroke characteristic) of the piston 13, that is, the change of the top dead center position and the bottom dead center position of the piston 13. Changed to

  The variable compression ratio mechanism 14 is disposed in a crank chamber 31 defined by the cylinder block 11 and an oil pan 30 attached to the lower surface of the cylinder block 11.

  The oil pan 30 includes a cylindrical upper oil pan 30a and a dish-shaped lower oil pan 30b. The upper oil pan 30a is attached to the lower surface of the cylinder block 11, and the lower oil pan 30b is attached to the lower surface of the upper oil pan 30a. ing. Note that reference numeral 32 in FIG. 1 denotes engine oil staying in the oil pan 30. 1 is an oil amount sensor that detects the amount of engine oil 32 in the oil pan 30 from the height of the oil surface in the oil pan 30. The height of the oil level in the oil pan 30 is, for example, a distance from the bottom surface of the oil pan 30 to the oil level along the vertical direction at a predetermined position in the oil pan 30.

  The control unit 29 is a known digital computer having a CPU, a ROM, a RAM, and an input / output interface. For example, the crank angle sensor 36 capable of detecting the engine speed together with the crank angle of the crankshaft 15, an accelerator pedal by the driver Signals from various sensors such as an accelerator pedal sensor 37 that detects the amount of depression (not shown), an angular position sensor 38 that detects the rotational position (rotation angle) of the control shaft 19, and the oil amount sensor 33 described above are input. Has been.

  The control unit 29 controls the fuel injection valve (not shown), the ignition plug (not shown), the actuator 28 of the variable compression ratio mechanism 14 and the like based on signals input from these various sensors. A signal is output to comprehensively control the fuel injection amount, fuel injection timing, ignition timing, engine speed, compression ratio, and the like.

  The oil amount of the engine oil 32 is managed so as to be within a predetermined allowable range, but the oil amount may increase even within the predetermined allowable range. When the amount of engine oil 32 is large, the oil level in the oil pan 30 rises relatively. Therefore, in the variable compression ratio mechanism 14 in which the control shaft 19 is disposed below the crankshaft 15, when the amount of engine oil 32 in the oil pan 30 increases, the control link 21 connected to the control shaft 19 is connected to the control link 21. On the other hand, the engine oil 32 is likely to interfere relatively, and the friction may increase.

  Therefore, when the detection value of the oil amount sensor 33 is equal to or greater than a predetermined value set in advance, the control link 21 is connected to suppress interference between the control link 21 and the engine oil 32 in the oil pan 30. The control shaft 19 is rotated so that the eccentric shaft portion 20 is positioned upward.

  Accordingly, even when the amount of the engine oil 32 is large, the engine oil 32 in the oil pan 30 does not easily interfere with the control link 21, and the increase in the friction of the control link 21 due to the engine oil 32 is suppressed. be able to.

As shown in FIG. 2, the variable compression ratio mechanism 14 is set such that the compression ratio becomes a relatively low compression ratio when the eccentric shaft portion 20 of the control shaft 19 moves upward. 2 is an explanatory view schematically showing the periphery of the control shaft 19, and the vertical direction in FIG. 2 is the same as the vertical direction in FIG.

  Therefore, when the control shaft 19 is rotated so that the eccentric shaft portion 20 is positioned above to suppress the interference between the control link 21 and the engine oil 32, the compression ratio is lowered, and the thermal efficiency is relatively lowered. As a result, the fuel consumption is relatively increased.

  However, when the inventor of the present application compares the suppression of deterioration of fuel consumption due to friction reduction and the deterioration of fuel consumption due to reduction in compression ratio, even if the compression ratio is decreased to reduce friction, the result It has been found that the effect of suppressing the deterioration is more than compensated for the deterioration of fuel consumption due to the reduction in compression ratio.

  Therefore, when the oil level of the engine oil 32 in the oil pan 30 is high and the engine oil 32 interferes with the control link 21, the control shaft 19 is rotated so that the eccentric shaft portion 20 is positioned upward. By making it, it can suppress the deterioration of a fuel consumption generally.

  FIG. 3 is a flowchart showing an example of compression ratio control according to the oil amount of the engine oil 32.

  In S1, the amount of engine oil 32, the engine speed, and the load (accelerator opening) are read.

  In S2, it is determined whether the amount of engine oil 32 is equal to or greater than a predetermined value. That is, it is determined whether or not the oil level of the engine oil 32 in the oil pan 30 is equal to or greater than a predetermined value. If the oil amount of the engine oil 32 is equal to or greater than the predetermined value, the process proceeds to S3, and if the oil amount of the engine oil 32 is not equal to or greater than the predetermined value, the process proceeds to S4.

  In S3, an oil level correction value that is a correction amount of the compression ratio according to the oil amount of the engine oil 32 is calculated. The oil level correction value is calculated using, for example, an oil level correction value calculation map stored in the control unit 29 in advance. For example, as shown in FIG. 4, the oil level correction value calculation map is set so that the oil level correction value calculated as the oil amount of the engine oil 32 increases. In S4, the oil level correction value is set to zero. The oil level correction value calculation map may calculate the oil level correction value not from the oil amount of the engine oil 32 but from the height of the oil level of the engine oil 32 in the oil pan 30.

  In S5, the target compression ratio is calculated by subtracting the oil level correction value from the reference compression ratio determined by the operating state. Here, the reference compression ratio is calculated using, for example, a reference compression ratio calculation map stored in the control unit 29 in advance. For example, as shown in FIG. 5, the reference compression ratio calculation map calculates the reference compression ratio according to the load and the engine speed.

  In S6, the actuator 28 is rotationally driven so that the compression ratio of the internal combustion engine 10 becomes the target compression ratio calculated in S5.

  When the oil level of the engine oil 32 in the oil pan 30 is high, the friction due to the interference between the control link 21 and the engine oil 32 increases relatively as the engine speed increases. Therefore, when the oil level of the engine oil 32 in the oil pan 30 is high, the control shaft 19 may be rotated so that the eccentric shaft portion 20 is positioned upward as the engine speed increases.

  Thereby, when the oil level of the engine oil 32 in the oil pan 30 is high and the engine speed is high, deterioration of fuel consumption can be further suppressed.

DESCRIPTION OF SYMBOLS 10 ... Internal combustion engine 13 ... Piston 14 ... Variable compression ratio mechanism 15 ... Crankshaft 16 ... Crankpin 17 ... Lower link 18 ... Upper link 19 ... Control shaft 20 ... Eccentric shaft part 21 ... Control link 27 ... Gear mechanism 28 ... Actuator 29 ... Control unit 31 ... Crank chamber 32 ... Engine oil 33 ... Oil quantity sensor

Claims (3)

A lower link rotatably connected to a crankpin of the crankshaft; an upper link connecting the lower link and the piston; a control shaft disposed below the crankshaft; and an eccentric shaft portion of the control shaft And a control link for connecting the lower link, and a variable compression ratio mechanism capable of continuously changing the compression ratio of the internal combustion engine according to the rotational position of the control shaft,
In the control apparatus for an internal combustion engine, wherein the variable compression ratio mechanism is disposed in a crank chamber defined by a cylinder block and an oil pan attached to the lower surface of the cylinder block.
An oil amount sensor for detecting the amount of oil in the oil pan,
A control device for an internal combustion engine, wherein when the amount of oil in the oil pan becomes equal to or greater than a predetermined amount, the control shaft is rotated so that the eccentric shaft portion is positioned upward.   The control apparatus for an internal combustion engine according to claim 1, wherein the variable compression ratio mechanism has a lower compression ratio as the eccentric shaft portion is positioned higher.   3. The control device for an internal combustion engine according to claim 1, wherein the control shaft is rotated so that the eccentric shaft portion is positioned upward as the engine speed increases.

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