JP2013117172A - Spark-ignition type internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the erroneous detection of a mechanical compression ratio variation even if the pitching oscillation of a cylinder block is generated in a cylinder arrangement direction.SOLUTION: A spark-ignition type internal combustion engine includes: a cylinder block to align and define a plurality of cylinder bores; a variable compression ratio mechanism changing the capacity of a combustor chamber by relatively moving the cylinder block with respect to a crank case, and varies the mechanical compression ratio; and a lift amount sensor detecting a relative lift amount of the cylinder block with respect to the crank case where a filter means filters a signal outputted from the lift amount sensor to remove a signal of a specific frequency component which is determined according to an engine rotation speed from the signal outputted from the lift amount sensor, and the variable compression ratio mechanism controls the mechanical compression ratio based on the signal after being filtered by the filter means.

Description

  The present invention relates to a spark ignition internal combustion engine, and more particularly to a spark ignition internal combustion engine having a variable compression ratio mechanism.

  In order to improve the fuel efficiency and output performance of an internal combustion engine, a spark ignition internal combustion engine having a variable compression ratio mechanism that can change the mechanical compression ratio of the internal combustion engine has been proposed. As a variable compression ratio mechanism capable of changing the mechanical compression ratio in such a technique, a cam mechanism is used to make a cylinder block, which is an engine element constituting the combustion chamber of the internal combustion engine, relatively to the crankcase. To change the mechanical compression ratio of the internal combustion engine by changing the volume of the combustion chamber, and when the mechanical compression ratio is reduced, the combustion chamber volume is controlled to be increased. On the other hand, when the mechanical compression ratio is increased, it is known that the combustion chamber volume is controlled to be reduced.

  In Patent Document 1, a variable compression ratio device that detects a mechanical compression ratio based on an output value of a lift amount sensor that detects a relative position (lift amount) between a cylinder block and a crankcase, and detects the mechanical compression ratio. Based on the output value of the lift amount sensor when the mechanism member is at the reference position or the reference angle in order to avoid the occurrence of a failure even when a large deviation occurs in the output value of the lift amount sensor for A variable compression ratio device configured to be able to correct the output value of the lift amount sensor is disclosed.

JP 2009-144560 A

  By the way, in an internal combustion engine having a variable compression ratio device as described above and having a plurality of cylinders, the cylinder block moves away from the crankcase due to the generation of combustion pressure in the cylinder. Along with this, the camshaft constituting the variable compression ratio device is pressed by the cylinder block side support portion, whereby both ends of the cylinder block are displaced, and the pitching oscillation of the cylinder block in the cylinder arrangement direction occurs. There is a case.

  In a variable compression ratio mechanism for detecting a mechanical compression ratio based on an output value of a lift amount sensor for detecting a relative position between a cylinder block and a crankcase, that is, for detecting a lift amount of the cylinder block with respect to the crankcase The occurrence of the pitching oscillation as described above is based on the output from the lift amount sensor, for example, the mechanical compression ratio is changing even though the mechanical compression ratio is not actually changing. In some cases, erroneous detection of fluctuations in the mechanical compression ratio may occur.

  In view of the above-described problems, the present invention is a spark ignition internal combustion engine including a cylinder block configured to align and define a plurality of cylinder bores, and the cylinder block is moved relative to a crankcase. A variable compression ratio mechanism capable of changing the mechanical compression ratio by changing the volume of the combustion chamber, and a lift amount sensor for detecting the relative lift amount of the cylinder block with respect to the crankcase, the lift amount sensor In a spark ignition type internal combustion engine that controls the mechanical compression ratio with a variable compression ratio mechanism based on the output value of the cylinder, when both ends of the cylinder block are displaced and the pitching oscillation of the cylinder block in the alignment direction of the cylinder bore occurs The spark ignition type makes it possible to suppress false detection of mechanical compression ratio fluctuations based on the output value from the lift amount sensor. An object of the present invention is to provide a combustion engine.

  According to the first aspect of the present invention, there is provided a spark ignition type internal combustion engine comprising a cylinder block configured to align and define a plurality of cylinder bores, the cylinder block being moved relative to a crankcase. Spark ignition comprising: a variable compression ratio mechanism capable of changing the mechanical compression ratio by changing the volume of the combustion chamber by causing a lift, and a lift amount sensor for detecting a relative lift amount of the cylinder block with respect to the crankcase Filtering means for filtering a signal output from the lift amount sensor so as to remove a signal of a specific frequency component determined according to the engine speed from the signal output from the lift amount sensor in the internal combustion engine And a mechanical compression ratio by the variable compression ratio mechanism based on the signal after being filtered by the filter means. Performing control, spark ignition internal combustion engine is provided.

  In the internal combustion engine having the variable compression ratio mechanism as described above, when the pitching fluctuation of the cylinder block due to the generation of the combustion pressure in the cylinder occurs, the lift for detecting the relative lift amount of the cylinder block with respect to the crankcase From the quantity sensor, a signal affected by the pitching fluctuation is output, and the influence is different depending on the engine speed.

  Based on this, in the first aspect of the invention, the signal output from the lift amount sensor so as to remove the signal of the specific frequency component determined according to the engine speed from the signal output from the lift amount sensor. By providing the filter means for filtering the generated signal, the signal that is output from the lift amount sensor and that is affected by the pitching fluctuation of the cylinder block as described above is appropriately set according to the engine speed. Thus, even when the cylinder block pitching swings as described above, it is possible to suppress erroneous detection of the mechanical compression ratio fluctuation based on the output from the lift amount sensor.

  According to a second aspect of the present invention, the filter means filters the signal output from the lift amount sensor with a low-pass filter that passes a component having a frequency equal to or lower than a predetermined cutoff frequency determined according to the engine speed. A spark ignition type internal combustion engine according to claim 1 is provided.

  According to the invention described in each claim, it is a spark ignition type internal combustion engine including a cylinder block configured to align and define a plurality of cylinder bores, and the cylinder block is moved relative to the crankcase. A spark ignition internal combustion engine comprising: a variable compression ratio mechanism that can change the mechanical compression ratio by changing the volume of the combustion chamber, and a lift amount sensor that detects a relative lift amount of the cylinder block with respect to the crankcase In this case, it is possible to perform appropriate filtering according to the engine speed with respect to the signal output from the lift amount sensor, so that both ends of the cylinder block are displaced and the pitching oscillation of the cylinder block in the alignment direction of the cylinder bores is prevented. Suppresses false detection of mechanical compression ratio fluctuations based on the output from the lift amount sensor even if it occurs. Allowing the door, it exhibits a common effect.

1 is an overall view of an embodiment of a spark ignition internal combustion engine of the present invention. It is a disassembled perspective view of a variable compression ratio mechanism. 1 is a schematic side sectional view of an internal combustion engine. It is the figure which modeled the motion of the center of a block side circular cam, an eccentric shaft, and a case side circular cam. It is explanatory drawing which shows the pitching rocking | fluctuation of a cylinder block diagrammatically. It is a follow chart which shows one Embodiment of filtering control of the output value from the lift amount sensor by this invention. It is a figure which shows one Embodiment of the lift amount sensor production | generation waveform before filtering control shown in FIG. 6, and the filtering waveform after filtering control.

  The spark ignition internal combustion engine of the present invention will be described in detail below with reference to the drawings. FIG. 1 shows a side sectional view of an embodiment of a spark ignition type internal combustion engine of the present invention.

  Referring to FIG. 1, 1 is a crankcase, 2 is a cylinder block, 3 is a cylinder head, 4 is a piston, 5 is a combustion chamber, 6 is a spark plug disposed at the center of the top surface of the combustion chamber 5, and 7 is an intake air 8 is an intake port, 9 is an exhaust valve, and 10 is an exhaust port. The intake port 8 is connected to a surge tank 12 via an intake branch pipe 11, and a fuel injection valve 13 for injecting fuel into the corresponding intake port 8 is arranged in each intake branch pipe 11. The fuel injection valve 13 may be arranged in each combustion chamber 5 instead of being attached to each intake branch pipe 11.

  The surge tank 12 is connected to an air cleaner 15 via an intake duct 14, and a throttle valve 17 driven by an actuator 16 and an intake air amount detector 18 using, for example, heat rays are arranged in the intake duct 14. On the other hand, the exhaust port 10 is connected to a catalytic converter 20 containing, for example, a three-way catalyst via an exhaust manifold 19, and an air-fuel ratio sensor 21 is disposed in the exhaust manifold 19.

  On the other hand, in the embodiment shown in FIG. 1, the piston 4 is positioned at the compression top dead center by changing the relative position of the crankcase 1 and the cylinder block 2 in the cylinder axis direction at the connecting portion between the crankcase 1 and the cylinder block 2. Is provided with a variable compression ratio mechanism A capable of changing the volume of the combustion chamber 5 when the engine is operated, and a variable valve timing capable of controlling the closing timing of the intake valve 7 in order to change the actual start timing of the compression action. A mechanism B is provided.

  The electronic control unit 30 is composed of a digital computer, and is connected to each other by a bidirectional bus 31. A ROM (Read Only Memory) 32, a RAM (Random Access Memory) 33, a CPU (Microprocessor) 34, an input port 35 and an output port 36. It comprises. The output signal of the intake air amount detector 18 and the output signal of the air-fuel ratio sensor 21 are input to the input port 35 via the corresponding AD converters 37, respectively. A load sensor 41 that generates an output voltage proportional to the amount of depression of the accelerator pedal 40 is connected to the accelerator pedal 40, and the output voltage of the load sensor 41 is input to the input port 35 via the corresponding AD converter 37. The Further, a crank angle sensor 42 that generates an output pulse every time the crankshaft rotates, for example, 30 ° is connected to the input port 35. Further, the cylinder block 2 is provided with a lift amount sensor 43 for detecting the relative position (lift amount) between the cylinder block 2 and the crankcase 1, and the output voltage of the lift amount sensor 43 corresponds to the corresponding AD converter. 37 to the input port 35. On the other hand, the output port 36 is connected to the spark plug 6, the fuel injection valve 13, the throttle valve drive actuator 16, the variable compression ratio mechanism A, and the variable valve timing mechanism B through corresponding drive circuits 38.

  Next, the configuration of the variable compression ratio mechanism A of the present embodiment will be described with reference to FIGS. 2 is an exploded perspective view of the variable compression ratio mechanism A shown in FIG. 1, and FIG. 3 is a side sectional view of the internal combustion engine schematically shown.

  Referring to FIG. 2, a plurality of block-side protrusions 50 are formed below the both side walls of the cylinder block 2 so as to be spaced from each other. A cam insertion hole 51 is formed. These block side cam insertion holes 51 are formed on the same axis so as to be parallel to the arrangement direction of the cylinders.

  On the other hand, a plurality of case-side protrusions 52 are formed on the upper wall surface of the crankcase 1 so as to be fitted between the corresponding block-side protrusions 50 spaced apart from each other. Case-side cam insertion holes 53 each having a circular cross section are also formed in the portion 52. The case side cam insertion holes 53 are also formed on the same axis so as to be parallel to the cylinder arrangement direction, similarly to the block side cam insertion holes 51.

  As shown in FIG. 2, a pair of camshafts 54 and 55 are provided, and on the camshafts 54 and 55, every other one is rotatably inserted into each case-side cam insertion hole 53. A circular cam 56 is fixed. These case-side circular cams 56 are coaxial with the rotational axes of the camshafts 54 and 55. On the other hand, an eccentric shaft 57 arranged eccentrically with respect to the rotation axis of each camshaft 54, 55 extends between the case side circular cams 56, as shown in FIG. A circular cam 58 is eccentrically mounted for rotation. As shown in FIG. 2, these block-side circular cams 58 are arranged between the case-side circular cams 56, and these block-side circular cams 58 are rotatably inserted into the corresponding block-side cam insertion holes 51. ing.

  As shown in FIG. 2, a pair of worm gears 61, 62 having opposite spiral directions are attached to the rotation shaft 60 of the drive motor 59 in order to rotate the camshafts 54, 55 in opposite directions, respectively. Gears 63 and 64 that mesh with the worm gears 61 and 62 are fixed to end portions of the camshafts 54 and 55, respectively. In the present embodiment, by driving the drive motor 59, the volume of the combustion chamber when the piston 4 is located at the compression top dead center can be changed over a wide range.

  Next, a method for changing the compression ratio by the variable compression ratio mechanism A having the above-described configuration will be described in detail with reference to FIGS. FIG. 4 is a diagram modeling the movement of the center of the case-side circular cam 56, the eccentric shaft 57, and the block-side circular cam 58. 3 and 4, a is the center of the case-side circular cam 56, b is the center of the eccentric shaft 57, and c is the center of the block-side circular cam 58. In this embodiment, the diameter of the block-side circular cam 58 is larger than the diameter of the case-side circular cam 56 as shown in FIG. The distance m between the center b of the eccentric shaft 57 is longer than the distance n between the center a of the case side circular cam 56 and the center b of the eccentric shaft 57.

  3A and 4A, the drive motor 59 is driven to rotate the case-side circular cams 56 in opposite directions as indicated by arrows in FIG. 3A. Accordingly, when the camshafts 54 and 55 are rotated, the eccentric shaft 57 moves downward around the center a of the case-side circular cam 56. As the eccentric shaft 57 moves, the block-side circular cam 58 is rotated in the direction opposite to the direction indicated by the arrow in FIG. When the case-side circular cam 56 rotates 90 ° from the state shown in FIGS. 3A and 4A, the state shown in FIGS. 3B and 4B is obtained.

  Further, when the drive motor 59 is driven to rotate the camshafts 54 and 55 to rotate the case-side circular cam 56 in opposite directions as indicated by arrows in FIG. It moves further downward about the center a of the side circular cam 56. As the eccentric shaft 57 moves, the block-side circular cam 58 is also rotated in the direction indicated by the arrow in FIG. When the case-side circular cam 56 rotates 90 ° from the state shown in FIGS. 3B and 4B, the state shown in FIGS. 3C and 4C is obtained.

  Here, the block-side circular cam 58 and the case-side circular cam 56 are accommodated in the block-side cam insertion port 51 and the case-side cam insertion port 53, respectively, and cannot move in a direction perpendicular to the cylinder axis. . Accordingly, the block-side circular cam 58 or the case-side circular cam 56 can be relatively moved only in a direction parallel to the cylinder axis. Therefore, the cams 56 and 58 are always positioned on the same straight line l parallel to the cylinder axis. To do. Therefore, the case-side circular cams 56 fixed on the camshafts 54 and 55 are rotated in opposite directions as shown by solid arrows in FIG. 3A from the state shown in FIG. As a result, the center c of the block-side circular cam 58 is moved downward so as to approach the center a of the case-side circular cam 56.

  As can be seen by comparing FIGS. 3A to 3C, the relative position (lift amount) of the cylinder block 2 with respect to the crankcase 1 is the center a of the case-side circular cam 56 and the center c of the block-side circular cam 58. The cylinder block 2 moves away from the crankcase 1 as the distance between the center a of the case side circular cam 56 and the center c of the block side circular cam 58 increases. When the cylinder block 2 moves away from the crankcase 1, the volume of the combustion chamber 5 when the piston 4 is located at the compression top dead center increases. Therefore, the volume of the combustion chamber 5 when the piston 4 is located at the compression top dead center (hereinafter referred to as “combustion chamber volume”) can be changed by rotating the camshafts 54 and 55.

  Even if the volume of the combustion chamber 5 when the piston 4 is located at the compression top dead center is changed by rotating the camshafts 54 and 55 in this way, the stroke volume of the piston 4 during the compression stroke (the piston 4 The volume of the combustion chamber 5 that changes when moving from the intake bottom dead center to the compression top dead center does not change. Therefore, the compression ratio represented by (combustion chamber volume + stroke volume) / combustion chamber volume changes according to the change of the combustion chamber volume. That is, according to the variable compression ratio mechanism A of the present embodiment, the compression ratio of the internal combustion engine can be changed by rotating the camshafts 54 and 55 by the drive motor 59.

  The variable compression ratio mechanism A shown in FIGS. 1 to 4 is an example, and any type of variable compression ratio mechanism can be used as long as the compression ratio can be changed by driving an actuator such as a drive motor. Can be used.

  By the way, in the internal combustion engine having the variable compression ratio mechanism A configured as described above, as described above, when combustion pressure is generated in the cylinder, the pitching oscillation of the cylinder block 2 in the cylinder arrangement direction occurs. sell.

  FIG. 5 is an explanatory view schematically showing the pitching swing of the cylinder block as described above. In FIG. 5, 91 is a first cylinder bore, 92 is a second cylinder bore, 93 is a third cylinder bore, and 94 is a fourth cylinder bore. As shown in FIG. 5, when combustion pressure is generated in the cylinder on one end side in the cylinder arrangement direction, that is, in the alignment direction of the cylinder bores of the cylinder block 2, the portion of the cylinder block 2 corresponding to the cylinder is It is pressed away from the crankcase 1. Along with this, the camshaft is pressed away from the crankcase 1 by the block-side protrusion 50 serving as the cylinder block-side support. On the other hand, a reaction force in a direction opposite to the above-described direction acts on a portion of the camshaft corresponding to the case-side protruding portion 52 serving as a crankcase-side support portion.

  As a result, the camshaft is bent, and both ends of the cylinder block 2 are displaced as shown by the dotted lines in FIG. 5, so that the cylinder block 2 is aligned in the cylinder arrangement direction, that is, the cylinder bore alignment direction of the cylinder block 2. Pitching oscillation can occur.

  Such occurrence of pitching oscillation of the cylinder block 2 is mechanically compressed by a variable compression ratio mechanism based on an output value from a lift amount sensor 43 that detects a relative lift amount of the cylinder block 2 with respect to the crankcase 1. In an internal combustion engine that controls the ratio, for example, based on the output from the lift amount sensor 43 such that the mechanical compression ratio is changing even though the mechanical compression ratio is not actually changing. In some cases, erroneous detection of fluctuations in the mechanical compression ratio may occur.

  In other words, in an internal combustion engine equipped with the variable compression ratio mechanism as described above, when the cylinder block pitching swings due to the generation of combustion pressure in the cylinder, the lift amount of the cylinder block relative to the crankcase is detected. From the lift amount sensor, the signal affected by the pitching fluctuation is output, and the influence is different depending on the engine speed. In some cases, erroneous detection of fluctuations in the mechanical compression ratio based on the output may be caused.

  Based on this, in the present invention, by performing appropriate filtering according to the engine speed for the signal output from the lift amount sensor, both ends of the cylinder block are displaced and the cylinder bores are aligned. Even when the pitching swing of the cylinder block in the direction occurs, it is possible to suppress erroneous detection of the mechanical compression ratio fluctuation based on the output from the lift amount sensor. More specifically, filter means for filtering the signal output from the lift amount sensor so as to remove the signal of the specific frequency component determined according to the engine speed from the signal output from the lift amount sensor. By providing, the signal output from the lift amount sensor and affected by the pitching fluctuation of the cylinder block as described above can be appropriately removed according to the engine speed, Even when the pitching swing of the cylinder block as described above occurs, it is possible to suppress erroneous detection of the mechanical compression ratio fluctuation based on the output from the lift amount sensor.

  FIG. 6 is a follow chart showing an embodiment of the filtering control of the output value from the lift amount sensor according to the present invention. In the filtering control shown in FIG. 6, first, a signal output from the lift amount sensor 43 is acquired in Step 101, and an engine speed is acquired in Step 201 and Step 202, and shut-off according to the machine speed is performed. Determine the frequency. Then, in the subsequent step 102, the cutoff frequency determined in step 202 is set to appropriately remove the signal output from the lift amount sensor 43 and affected by the pitching fluctuation of the cylinder block 2. Based on this, the signal output from the lift amount sensor 43 acquired in step 101 is filtered.

  That is, the cutoff frequency determined in step 202 is to remove the signal affected by the pitching fluctuation of the cylinder block 2 in order to appropriately remove the signal affected by the pitching fluctuation of the cylinder block 2. It serves as a threshold value.

  In determining such a cut-off frequency, a process suitable for each engine specification is selected on the basis of a pre-evaluation test or an analytical evaluation, and the cut-off frequency is determined. For example, in the engine specification, a signal that is affected by the pitching fluctuation of the cylinder block 2 in a process in which the primary frequency of rotation, that is, the frequency corresponding to the engine speed, is determined as a cutoff frequency from an evaluation test or analysis evaluation in advance. When it is confirmed that it is possible to appropriately remove the engine speed, the frequency corresponding to the engine speed acquired in step 201 is determined as the cutoff frequency. Here, for example, when the engine speed is 3000 rpm, 50 Hz (= 3000 ÷ 60) is the frequency corresponding to the engine speed, that is, the primary rotation frequency.

  Further, for example, in the engine specification, the process of setting the engine cycle frequency, that is, the frequency corresponding to one cycle of the engine, to the cutoff frequency is affected by the pitching fluctuation of the cylinder block 2 based on the evaluation test and analysis evaluation in advance. The engine cycle frequency is configured to be determined as the cut-off frequency when it is confirmed that it is possible to properly remove the signal.

  Incidentally, in the present embodiment, the filtering on the output signal from the lift amount sensor 43 in step 102 is executed by a low-pass filter that passes a component having a frequency equal to or lower than a predetermined cutoff frequency determined according to the engine speed. To do. That is, in this embodiment, the signal output from the lift amount sensor 43 is filtered so as to remove the signal of the specific frequency component determined according to the engine speed from the signal output from the lift amount sensor 43. The filter means is configured to include the low-pass filter as described above.

  In steps 103 and 104 following step 102, the mechanical compression ratio is controlled by the variable compression ratio mechanism based on the signal after being filtered by the filter means. That is, in step 103 and step 104, the relative lift amount of the cylinder block 2 with respect to the crankcase 1 is detected based on the signal output from the lift amount sensor 43 and filtered by the low-pass filter. The mechanical compression ratio is calculated based on the detected lift amount, and the mechanical compression ratio is controlled by the variable compression ratio mechanism.

  According to the filtering control of the output signal from the series of lift amount sensors 43 as described above, the signal output from the lift amount sensor 43 and influenced by the pitching oscillation of the cylinder block 2 as described above. Can be appropriately removed in accordance with the engine speed, so that even if the pitching fluctuation of the cylinder block 2 occurs as described above, the error in the mechanical compression ratio fluctuation based on the output from the lift amount sensor 43 can be reduced. It is possible to suppress detection.

  FIG. 7 is a diagram illustrating an embodiment of the lift amount sensor generation waveform before the filtering control shown in FIG. 6 and the filtering waveform after the filtering control. As can be understood from FIG. 7, according to the filtering control of the output signal from the series of lift amount sensors 43 as shown in FIG. 6, the cylinder block as described above is a signal output from the lift amount sensor 43. 2 can be appropriately removed in accordance with the engine speed, and thus the lift amount sensor 43 can be used even when the pitching oscillation of the cylinder block 2 occurs as described above. It is possible to suppress erroneous detection of fluctuations in the mechanical compression ratio based on the output from. In addition, making it possible to suppress such erroneous detection of mechanical compression ratio fluctuations makes it possible to suppress unnecessary actuator operation for operating the variable compression ratio mechanism, thereby reducing actuator power consumption. This makes it possible to reduce fuel consumption loss by reducing the wear of the brush by reducing the actuator operating current.

DESCRIPTION OF SYMBOLS 1 Crankcase 2 Cylinder block 3 Cylinder head 4 Piston 5 Combustion chamber 43 Lift amount sensor 50 Block side protrusion part 52 Case side protrusion part 54,55 Camshaft 56 Case side circular cam 57 Eccentric shaft 58 Block side circular cam A Variable compression ratio mechanism

Claims (2)

A spark ignition internal combustion engine comprising a cylinder block configured to align and define a plurality of cylinder bores, wherein the volume of a combustion chamber is changed by moving the cylinder block relative to a crankcase. In a spark ignition internal combustion engine comprising: a variable compression ratio mechanism that can change a mechanical compression ratio; and a lift amount sensor that detects a relative lift amount of the cylinder block with respect to the crankcase.
Filter means for filtering the signal output from the lift amount sensor so as to remove the signal of the specific frequency component determined according to the engine speed from the signal output from the lift amount sensor; A spark ignition type internal combustion engine that controls a mechanical compression ratio by the variable compression ratio mechanism based on a signal after being filtered by a filter means.   2. The spark ignition type according to claim 1, wherein the filter means filters a signal output from the lift amount sensor with a low-pass filter that allows a component having a frequency equal to or lower than a predetermined cutoff frequency determined according to the engine speed to pass. Internal combustion engine.

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