JP2014114781A - Internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an internal combustion engine for reducing a mechanical compression ratio when a variable compression ratio mechanism is malfunctioned.SOLUTION: The internal combustion engine includes a crank case, a cylinder block, the variable compression ratio mechanism including a clutch arranged in a driving force transmission passage for transmitting the rotating force of a driving motor to an eccentric shaft, and an abnormality detection device for detecting the abnormality of the clutch. The clutch is formed to transmit the rotating force from the input side corresponding to one rotating direction to induce the mechanical compression ratio to be reduced and to the other rotating direction to induce the mechanical compression ratio to be increased, and to interrupt the rotating force from the output side corresponding to one rotating direction. When the abnormality of the clutch is detected in the case of rotating the eccentric shaft in one rotating direction, the variable compression ratio mechanism rotates the eccentric shaft in the other rotating direction over the moving range of the eccentric shaft in normal operation to reduce the mechanical compression ratio down to preset one.

Description

  The present invention relates to an internal combustion engine.

  In the combustion chamber of the internal combustion engine, the air-fuel mixture is ignited in a compressed state. It is known that the compression ratio when the air-fuel mixture is compressed affects the output and fuel consumption of the internal combustion engine. By increasing the compression ratio, the output torque can be increased and the thermal efficiency can be improved. However, it is known that abnormal combustion such as knocking occurs when the compression ratio is too high.

  Japanese Patent Application Laid-Open No. 2004-169660 discloses a variable compression ratio engine including a compression ratio changing mechanism that changes the compression ratio according to the operating state of the engine. In this variable compression ratio engine, if any trouble occurs under the condition of a high compression ratio, the power transmission between the compression ratio changing mechanism and the servo motor is cut off by the clutch. And it is disclosed that a piston receives the combustion pressure of the fuel of a combustion chamber, the position of the top dead center of a piston leaves | separates from the ceiling wall of a combustion chamber, and an engine will be in the state of a low compression ratio.

  Japanese Patent Laid-Open No. 2007-263285 discloses an actuator provided with a torque diode clutch in a rotation transmission path between an electric motor and a nut of a ball screw mechanism. It is disclosed that this torque diode clutch transmits an input from an electric motor to a ball screw mechanism and interrupts a reverse input.

  Japanese Patent Application Laid-Open No. 2010-255460 discloses a variable compression in which an eccentric shaft disposed between a crankcase and a cylinder block and a relative position between the cylinder block and the crankcase are changed by changing a rotational position of the eccentric shaft. A ratio system is disclosed. This variable compression ratio system includes a clutch mechanism that switches connection or disconnection between a first part that operates while contacting a member on the cylinder block side and a second part that operates while contacting a member on the crankcase side in the eccentric shaft. ing. It is disclosed that the mechanical compression ratio of an internal combustion engine is reduced by separating the first part and the second part when a failure occurs in a drive system including an eccentric shaft and an actuator.

  Japanese Patent Application Laid-Open No. 2004-183594 discloses a variable compression ratio engine that includes a compression ratio changing mechanism that moves a cylinder block relative to a lower case and that transmits a rotational driving force of a servo motor via a gear ratio switching box. Yes. When transmitting the driving force, the servo motor is rotated forward and backward by using a forward / reverse one-way clutch and a large / small gear together. With this compression ratio change mechanism, the motor rotation driving force is transmitted at high speed when changing from a high compression ratio to a low compression ratio, and the motor rotation driving force is transmitted with a large torque when changing from a low compression ratio to a high compression ratio. Is disclosed.

JP 2004-169660 A JP 2007-263285 A JP 2010-255460 A JP 2004-183594 A

  As the variable compression ratio mechanism for changing the compression ratio, the compression ratio can be changed by adopting a mechanism for changing the size of the combustion chamber when the piston reaches top dead center. In an internal combustion engine having such a variable compression ratio mechanism, when the fuel burns, a force acts in a direction in which the volume of the combustion chamber increases with respect to the members constituting the combustion chamber by the pressure at this time.

  In the internal combustion engine disclosed in the above Japanese Patent Application Laid-Open No. 2004-169660, the power from the motor that changes the compression ratio is completely separated by the clutch, so that a force acts in the direction of increasing the volume of the combustion chamber. The internal combustion engine can be brought into a low compression ratio state. However, it is necessary to dispose a clutch that completely cuts off the transmission of power in the middle of the path for transmitting power from the motor to the mechanism for changing the volume of the combustion chamber. That is, it is necessary to arrange a clutch that allows the cylinder block to move freely with respect to the crankcase. In an internal combustion engine in which such a clutch is not disposed, there is a problem that the mechanical compression ratio cannot be lowered when the variable compression ratio mechanism becomes malfunctioning. For example, if the variable compression ratio mechanism malfunctions and is maintained at a high compression ratio, abnormal combustion such as knocking may occur.

  Alternatively, when the variable compression ratio mechanism is malfunctioning and maintained at a high compression ratio, abnormal combustion such as knocking can be suppressed by reducing the amount of air and fuel sucked into the combustion chamber. However, the output of the internal combustion engine is limited. For this reason, there is a problem in that the output is reduced against the user's intention and the drivability is deteriorated when the internal combustion engine is arranged in the vehicle.

  An object of the present invention is to provide an internal combustion engine that lowers the mechanical compression ratio when the variable compression ratio mechanism malfunctions.

  An internal combustion engine of the present invention includes a support structure including a crankcase, a cylinder block supported by the support structure via an eccentric shaft, a drive unit that rotates the eccentric shaft, and a rotational force of the drive unit as an eccentric shaft. A variable compression ratio mechanism including a clutch arranged in a driving force transmission path for transmission and formed so that a cylinder block moves relative to a support structure; and an abnormality detection device for detecting an abnormality of the clutch. Prepare. The variable compression ratio mechanism has a predetermined range of movement of the eccentric shaft in normal operation, and by rotating the eccentric shaft in one direction of rotation, it moves relative to the support structure in the direction of separating the cylinder block, By rotating the eccentric shaft in the other rotation direction, the eccentric block is formed to move relative to the support structure in the direction in which the cylinder block is brought closer. The clutch is configured to transmit the rotational force from the input side corresponding to one rotational direction and the other rotational direction, and to block the rotational force from the output side corresponding to the one rotational direction. When the drive machine rotates the eccentric shaft in one rotation direction, when the abnormality detection device detects that the clutch is abnormal, the variable compression ratio mechanism exceeds the movement range of the eccentric shaft and the other rotation direction. By rotating the eccentric shaft, the cylinder block is moved relative to the support structure in a direction away from the support structure, and the mechanical compression ratio is reduced to a preset value.

  In the above invention, the variable compression ratio mechanism lowers the mechanical compression ratio to a preset mechanical compression ratio, further increases the mechanical compression ratio by rotating the eccentric shaft in the other rotational direction, and increases the mechanical compression ratio. From this state, the eccentric shaft can be rotated in one rotational direction, and the abnormality detection device can determine whether or not the clutch is abnormal.

  According to the present invention, it is possible to provide an internal combustion engine that lowers the mechanical compression ratio when the variable compression ratio mechanism malfunctions.

1 is a schematic overall view of an internal combustion engine in an embodiment. It is a general | schematic exploded perspective view of the variable compression ratio mechanism in embodiment. It is a 1st schematic sectional drawing of the variable compression ratio mechanism explaining the change of the mechanical compression ratio in embodiment. It is a 2nd schematic sectional drawing of the variable compression ratio mechanism explaining the change of the mechanical compression ratio in embodiment. It is a 3rd schematic sectional drawing of the variable compression ratio mechanism explaining the change of the mechanical compression ratio in embodiment. It is an expansion schematic sectional drawing explaining the movement range of the eccentric shaft at the time of the normal driving | operation in embodiment. It is the 1st schematic sectional view of the clutch in an embodiment. It is a 2nd schematic sectional drawing of the clutch in embodiment. It is the 1st schematic sectional view of a clutch when reducing the mechanical compression ratio in an embodiment. It is a 2nd schematic sectional drawing of a clutch when reducing the mechanical compression ratio in embodiment. It is a 1st schematic sectional drawing of a clutch when raising the mechanical compression ratio in embodiment. It is a 2nd schematic sectional drawing of a clutch when raising the mechanical compression ratio in embodiment. It is the 1st schematic sectional view of a clutch at the time of performing the 1st operation control of an embodiment. It is a schematic sectional drawing of the variable compression ratio mechanism at the time of performing the 1st operation control of embodiment. It is a flowchart of the 1st operation control in an embodiment. It is a 2nd schematic sectional drawing of the clutch at the time of performing the 1st driving | operation control of embodiment. It is a flowchart of the 2nd control in an embodiment.

  The internal combustion engine in the embodiment will be described with reference to FIGS. In the present embodiment, a spark ignition type internal combustion engine attached to a vehicle will be described as an example. The internal combustion engine in the present embodiment includes a variable compression ratio mechanism that can change the mechanical compression ratio.

  FIG. 1 is a schematic overall view of an internal combustion engine according to an embodiment. The internal combustion engine includes a support structure including the crankcase 1. The support structure is formed to support the crankshaft. The internal combustion engine includes a cylinder block 2 and a cylinder head 3. A piston 4 is disposed in a hole formed in the cylinder block 2. A spark plug 6 is arranged at the center of the top surface of the combustion chamber 5 surrounded by the top surface of the piston 4 and the cylinder head 3.

  An intake port 8 and an exhaust port 10 are formed in the cylinder head 3. An intake valve 7 is disposed at the end of the intake port 8. The intake valve 7 opens and closes as the intake cam 49 rotates. An exhaust valve 9 is disposed at the end of the exhaust port 10. The intake port 8 is connected to a surge tank 12 via an intake branch pipe 11. 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 so as to inject fuel directly into each combustion chamber 5 instead of being attached to the intake branch pipe 11.

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

  The internal combustion engine in the present embodiment includes a variable compression ratio mechanism A that can change the volume of the combustion chamber 5 when the piston 4 is located at the compression top dead center. The variable compression ratio mechanism A is formed so as to change the relative position of the cylinder block 2 with respect to the crankcase 1 in the cylinder axial direction. A spring 65 as an urging member is disposed between the crankcase 1 and the cylinder block 2. The spring 65 is formed so as to bias the cylinder block 2 in a direction away from the crankcase 1.

  A relative position sensor 22 for detecting the relative position of the cylinder block 2 with respect to the crankcase 1 is attached to the crankcase 1 and the cylinder block 2. The relative position sensor 22 outputs an output signal indicating a change in the interval between the crankcase 1 and the cylinder block 2. A throttle opening sensor 24 for generating an output signal indicating the throttle valve opening is attached to the actuator 16 for driving the throttle valve.

  The control device for the internal combustion engine in the present embodiment includes an electronic control unit 30. Electronic control unit 30 in the present embodiment includes a digital computer. The digital computer includes 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 connected to each other by a bidirectional bus 31.

  Output signals of the intake air amount detector 18, air-fuel ratio sensor 21, relative position sensor 22, and throttle opening sensor 24 are input to the input port 35 via corresponding AD converters 37. 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. The output voltage of the load sensor 41 is input to the input port 35 via the corresponding AD converter 37. The required load can be detected from the output of the load sensor 41. Further, the input port 35 is connected to a crank angle sensor 42 that generates an output pulse every time the crankshaft rotates, for example, 30 °. From the output of the crank angle sensor 42, the crank angle and the engine speed can be detected.

  On the other hand, the output port 36 is connected to the ignition plug 6, the fuel injection valve 13, the actuator 16 for driving the throttle valve, and the variable compression ratio mechanism A through a corresponding drive circuit 38. These devices are controlled by the electronic control unit 30.

  FIG. 2 is an exploded perspective view of the variable compression ratio mechanism in the present embodiment. FIG. 3 shows a first schematic cross-sectional view of the variable compression ratio mechanism in the present embodiment. Referring to FIGS. 2 and 3, a plurality of protrusions 50 spaced from each other are formed below both side walls of cylinder block 2. Each protrusion 50 is formed with a cam insertion hole 51 having a circular cross section. On the other hand, the upper wall of the crankcase 1 is formed with a plurality of protrusions 52 that are fitted between the protrusions 50 at intervals. These protrusions 52 are also formed with cam insertion holes 53 having a circular cross section.

  The variable compression ratio mechanism in the present embodiment includes a pair of camshafts 54 and 55. On each of the cam shafts 54 and 55, circular cams 58 that are rotatably inserted into the respective cam insertion holes 53 are arranged. These circular cams 58 are coaxial with the rotational axes of the camshafts 54 and 55. On the other hand, on both sides of each circular cam 58, eccentric shafts 57 arranged eccentrically with respect to the rotational axes of the respective cam shafts 54, 55 extend as shown in FIG. Another circular cam 56 is eccentrically attached to the eccentric shaft 57 so as to be rotatable. As shown in FIG. 2, the circular cams 56 are disposed on both sides of each circular cam 58. These circular cams 56 are rotatably inserted into the corresponding cam insertion holes 51. The cylinder block 2 is supported on the crankcase 1 via an eccentric shaft 57. A rotation angle sensor 25 that generates an output signal representing the rotation angle of the camshaft 55 is attached to the camshaft 55. The output of the rotation angle sensor 25 is input to the electronic control unit 30.

  FIG. 4 shows a second schematic cross-sectional view of the variable compression ratio mechanism in the present embodiment. FIG. 5 shows a third schematic cross-sectional view of the variable compression ratio mechanism in the present embodiment. 3 to 5 illustrate the function of the variable compression ratio mechanism when changing the mechanical compression ratio in normal operation. When the circular cams 58 arranged on the camshafts 54 and 55 are rotated in opposite directions from the state shown in FIG. 3, the eccentric shafts 57 move toward each other. The eccentric shaft 57 rotates around the rotation axis of the respective camshafts 54 and 55. At this time, the circular cam 56 rotates in the opposite direction to the circular cam 58 in the cam insertion hole 51, and the position of the eccentric shaft 57 is changed from a high position to an intermediate height position as shown in FIG. Next, when the circular cam 58 is further rotated in the direction indicated by the arrow 69, the eccentric shaft 57 is at the lowest position as shown in FIG.

  3 to 5 show the positional relationship between the center a of the circular cam 58, the center b of the eccentric shaft 57, and the center c of the circular cam 56 in each state. As can be seen by comparing FIGS. 3 to 5, the relative positions of the crankcase 1 and the cylinder block 2 are determined by the distance between the center a of the circular cam 58 and the center c of the circular cam 56. As the distance between the center a of the circular cam 58 and the center c of the circular cam 56 increases, the cylinder block 2 moves away from the crankcase 1. That is, in the variable compression ratio mechanism A, the relative position between the crankcase 1 and the cylinder block 2 is changed by a link mechanism using a rotating cam. When the cylinder block 2 is separated from the crankcase 1, the volume of the combustion chamber 5 when the piston 4 is located at the compression top dead center increases. As the cylinder block 2 approaches the crankcase 1, the volume of the combustion chamber 5 when the piston 4 is located at the compression top dead center is reduced. Therefore, the volume of the combustion chamber 5 when the piston 4 is positioned at the compression top dead center can be changed by rotating the camshafts 54 and 55.

  As shown in FIG. 2, a pair of worms 61 and 62 having a spiral direction opposite to each other are attached to the rotating shaft 60 so that the camshafts 54 and 55 are rotated in opposite directions. Worm wheels 63 and 64 that mesh with the worms 61 and 62 are fixed to the ends of the camshafts 54 and 55, respectively. In this embodiment, the volume of the combustion chamber 5 when the piston 4 is located at the compression top dead center can be changed over a wide range by driving a drive motor 59 as a drive machine. The variable compression ratio mechanism is controlled by the electronic control unit 30, and a drive motor 59 that rotates the camshafts 54 and 55 is connected to the output port 36 via a corresponding drive circuit 39.

  As described above, the variable compression ratio mechanism according to the present embodiment has a variable volume of the combustion chamber 5 when the piston reaches the top dead center by moving the cylinder block 2 relative to the crankcase 1. Is formed. In the present embodiment, the compression ratio determined only from the stroke volume of the piston from the bottom dead center to the top dead center and the volume of the combustion chamber when the piston reaches the top dead center is referred to as a mechanical compression ratio. The mechanical compression ratio does not depend on the closing timing of the intake valve, etc., (mechanical compression ratio) = (combustion chamber volume when piston reaches top dead center + piston stroke volume) / (combustion chamber volume) Volume).

  In the state shown in FIG. 3, the volume of the combustion chamber 5 is large and the mechanical compression ratio is low. When the intake air amount is always constant, the actual compression ratio is low. On the other hand, in the state shown in FIG. 5, the volume of the combustion chamber 5 is small and the mechanical compression ratio is high. When the intake air amount is always constant, the actual compression ratio becomes high.

  The internal combustion engine in the present embodiment can change the actual compression ratio by changing the mechanical compression ratio during the operation period. For example, the mechanical compression ratio can be changed by a variable compression ratio mechanism according to the operating state of the internal combustion engine.

  Referring to FIGS. 3 to 5, eccentric shaft 57 rotates around the rotation shaft of cam shafts 54, 55, that is, the rotation shaft of circular cam 58. In order to increase the mechanical compression ratio, the eccentric shaft 57 is rotated in the direction indicated by the arrow 69. When lowering the mechanical compression ratio, the eccentric shaft 57 is rotated in the direction indicated by the arrow 68.

  FIG. 6 shows an enlarged schematic cross-sectional view for explaining the movement range of the eccentric shaft 57 in normal operation. The position 57a is the position of the eccentric shaft 57 when the mechanical compression ratio becomes maximum. The position 57b is a position of the eccentric shaft 57 when the mechanical compression ratio is minimized. The movement range of the eccentric shaft 57 is a range indicated by an arrow 106 when expressed using the center b of the eccentric shaft 57. The eccentric shaft 57 of the present embodiment moves within a range where the rotation angle of the center b when the center a of the circular cam 58 is the rotation center is 180 °. The movement range of the eccentric shaft 57 is not limited to this form, and may be a range where the rotation angle of the center b is smaller than 180 °.

  In the present embodiment, the rotation direction of the eccentric shaft 57 when the cylinder block 2 is moved relative to the crankcase 1 in the direction of separating the cylinder block 2 is referred to as one rotation direction. Further, the rotation direction of the eccentric shaft 57 when the cylinder block 2 is relatively moved with respect to the crankcase 1 is referred to as the other rotation direction. In the present embodiment, arrow 68 is one rotation direction, and arrow 69 is the other rotation direction.

  In the internal combustion engine in the present embodiment, the relative position sensor 22 can detect the relative position of the cylinder block 2 with respect to the crankcase 1. Based on the output of the relative position sensor 22, the relative position of the piston 4 with respect to the cylinder block 2 when the piston 4 is located at the top dead center can be estimated. The mechanical compression ratio can be calculated based on the relative position of the piston 4 with respect to the cylinder block 2.

  Referring to FIG. 2, the variable compression ratio mechanism in the present embodiment includes a clutch 70 arranged in a driving force transmission path for transmitting the rotational force of driving motor 59 to eccentric shaft 57. In the present embodiment, the clutch 70 has an input side connected to a rotary shaft 66 that transmits the rotational force of the drive motor 59 and an output side connected to a rotary shaft 60 that supports the worms 61 and 62.

  The clutch 70 in the present embodiment is a so-called reverse input cutoff clutch. The reverse input cutoff clutch transmits the rotational force from the input side in both directions, that is, the direction in which the cylinder block 2 is separated from and the direction toward the crankcase 1, and the output from the direction in which the cylinder block is separated from the crankcase 1. It is formed so as to block the rotational force. That is, the clutch 70 transmits the rotational force transmitted from the drive motor 59 to the worms 61 and 62, and interrupts the rotational force corresponding to one rotational direction of the eccentric shaft transmitted from the worms 61 and 62 to drive the clutch 70. It has a structure that does not transmit to the motor 59.

  FIG. 7 shows a first schematic cross-sectional view of clutch 70 in the present embodiment. FIG. 8 shows a second schematic cross-sectional view of clutch 70 in the present embodiment. FIG. 8 is a schematic cross-sectional view taken along the X-ray in FIG.

  With reference to FIGS. 7 and 8, clutch 70 of the present embodiment includes an outer ring 77. The outer ring 77 is fixed to the housing 78 by screws 85. The outer ring 77 is fixed without moving during the period in which the clutch 70 is driven. The clutch 70 has an output shaft 74. The output shaft 74 is connected to the rotating shaft 60 to which the worms 61 and 62 are fixed. The output shaft 74 rotates about the rotation shaft 88 as a rotation center. The output shaft 74 has a hole 75. A plurality of holes 75 are formed along the circumferential direction in which the output shaft 74 rotates. The output shaft 74 in the present embodiment has a polygonal cross section. In the example shown in FIG. 7, the output shaft 74 has a regular octagonal cross-sectional shape.

  The clutch 70 includes an input shaft 71. The input shaft 71 rotates about the rotation shaft 88 as a rotation center. The input shaft 71 is connected to a rotating shaft 66 that transmits the rotational force of the drive motor 59. The input shaft 71 has an insertion part 72 and a holding part 73. The insertion part 72 and the holding part 73 rotate integrally.

  The plurality of insertion portions 72 are formed at positions corresponding to the plurality of hole portions 75 of the output shaft 74. The insertion portion 72 is inserted into the hole 75 of the output shaft 74. The inner diameter of the hole portion 75 is formed to be larger than the outer diameter of the insertion portion 72. A gap is formed between the insertion portion 72 and the hole 75. The plurality of holding portions 73 are disposed between the outer ring 77 and the output shaft 74. The holding portion 73 faces the roller 80 and is formed so as to press the roller 80 when the input shaft 71 rotates in the direction in which the eccentric shaft 57 rotates in one rotation direction.

  A roller 80 is disposed in the space between the output shaft 74 and the outer ring 77. The roller 80 in the present embodiment is formed in a cylindrical shape. The roller 80 is connected to the holding portion 73 via a spring 81. The spring 81 urges the connected holding portion 73 in a direction to release the roller 80.

  A locking portion 86 for locking the roller 80 is formed by the output shaft 74 and the outer ring 77. The locking portion 86 is a portion where the distance between the end surface of the output shaft 74 and the inner surface of the outer ring 77 is gradually reduced along the direction in which the roller 80 is urged. The locking portion 86 is formed narrow so that the roller 80 does not pass through.

  Next, the operation when the clutch 70 in the present embodiment is normal will be described. The clutch 70 according to the present embodiment transmits the rotational force when the rotational force of the drive motor 59 is input so as to move the cylinder block 2 away from the crankcase 1. That is, when the drive motor 59 is driven in a direction in which the eccentric shaft 57 is rotated in one rotation direction, the rotational force of the drive motor 59 is transmitted to the worms 61 and 62. On the other hand, when the rotational force is transmitted from the worms 61 and 62 in the direction in which the eccentric shaft 57 rotates in one rotational direction, the clutch 70 interrupts the rotational force.

  In the present embodiment, the cylinder block 2 is biased by the spring 65 in a direction away from the crankcase 1. During the operation period of the internal combustion engine, a force acts in a direction in which the cylinder block 2 approaches the crankcase 1 due to the influence of gravity or the negative pressure of the combustion chamber 5 in the intake stroke of the combustion cycle. However, by arranging the spring 65, the cylinder block 2 is always urged in the direction away from the crankcase 1, and the occurrence of vibration or the like in the cylinder block 2 can be suppressed. Further, whenever fuel is burned in the combustion chamber 5, a force acts in a direction in which the cylinder block 2 is separated from the crankcase 1.

  With reference to FIG. 7, an arrow 100 is a direction corresponding to a direction in which the cylinder block 2 moves up with respect to the crankcase 1. That is, the rotation direction in which the combustion chamber 5 becomes large when the mechanical compression ratio becomes small and the piston 4 reaches top dead center is shown. As described above, a force is always applied to the cylinder block 2 in a direction away from the crankcase 1. For this reason, a force is applied to the output shaft 74 in the direction indicated by the arrow 100. The roller 80 is pressed by the spring 81 and is in contact with the locking portion 86. For this reason, a wedge effect is generated in the roller 80, the rotation of the output shaft 74 with respect to the outer ring 77 is prevented, and the output shaft 74 is locked. In this manner, the clutch 70 can block the rotational force from the output side corresponding to the direction in which the cylinder block 2 is separated from the crankcase 1.

  That is, when the drive motor 59 is not driven, the force in the direction in which the cylinder block 2 moves away from the crankcase 1 is transmitted to the clutch 70 via the camshafts 54 and 55, the worm wheels 63 and 64, and the worms 61 and 62. Is done. The roller 80 is locked to the locking portion 86, and the clutch 70 cuts off the rotational force from the output side.

  FIG. 9 is a first schematic cross-sectional view of the clutch 70 for explaining the operation when the mechanical compression ratio is lowered. When lowering the mechanical compression ratio, the cylinder block 2 is moved away from the crankcase 1. By driving the drive motor 59, the insertion portion 72 of the input shaft 71 rotates in the direction indicated by the arrow 101. The holding portion 73 comes into contact with the roller 80 before the insertion portion 72 comes into contact with the inner surface of the hole portion 75.

  FIG. 10 is a second schematic cross-sectional view of the clutch 70 for explaining the operation when the mechanical compression ratio is lowered. By further rotating the input shaft 71, the holding unit 73 presses the roller 80. The roller 80 moves away from the locking portion 86. That is, the wedge effect of the roller 80 disappears. Therefore, the output shaft 74 is unlocked and can rotate in the direction indicated by the arrow 100 with respect to the outer ring 77. When the insertion portion 72 of the input shaft 71 rotates in the direction indicated by the arrow 101, the insertion portion 72 can press the hole 75 of the output shaft 74 and rotate the output shaft 74. Thus, the rotational force of the input shaft 71 can be transmitted to the output shaft 74. Alternatively, since force is always applied to the output shaft 74 in the direction indicated by the arrow 100, the output shaft 74 rotates. The eccentric shaft 57 rotates in one rotation direction and can be moved in a direction to separate the cylinder block 2 from the crankcase 1.

  FIG. 11 is a first schematic cross-sectional view of the clutch 70 for explaining the operation when raising the mechanical compression ratio. In order to increase the mechanical compression ratio, the cylinder block 2 is moved in a direction closer to the crankcase 1. A force is applied to the output shaft 74 in the direction indicated by the arrow 100. By driving the drive motor 59, the insertion portion 72 and the holding portion 73 of the input shaft 71 are rotated in the direction indicated by the arrow 102. The insertion portion 72 of the input shaft 71 contacts the hole portion 75 of the output shaft 74.

  FIG. 12 is a second schematic cross-sectional view of the clutch 70 for explaining the operation when increasing the mechanical compression ratio. By rotating the insertion portion 72 in the direction indicated by the arrow 102, a force acts in a direction in which the roller 80 moves away from the locking portion 86. For this reason, the wedge effect of the roller 80 is released. When the insertion portion 72 of the input shaft 71 presses the hole 75 of the output shaft 74, the rotational force of the input shaft 71 can be transmitted to the output shaft 74. The output shaft 74 rotates in the direction indicated by the arrow 102. The roller 80 slides between the output shaft 74 and the outer ring 77. The holding portion 73 is disposed at a position away from the rollers 80 facing each other. As a result, the eccentric shaft 57 rotates in the other rotation direction, and the cylinder block 2 can be moved in a direction approaching the crankcase 1.

  By the way, referring to FIG. 9, for example, when the holding portion 73 is worn due to long-term use of the clutch 70, the holding portion 73 cannot sufficiently press the roller 80 when trying to reduce the mechanical compression ratio. There is. For this reason, the wedge effect of the roller 80 may not be canceled. Alternatively, when foreign matter is mixed between the roller 80 and the outer ring 77, the wedge effect of the roller 80 may not be canceled even if the holding unit 73 presses the roller 80. In such a case, the rotational force cannot be transmitted to the output shaft 74 even if the rotational force of the drive motor 59 is input in the direction in which the eccentric shaft 57 rotates in one rotational direction. That is, in the clutch 70, the rotational force of the input shaft 71 indicated by the arrow 101 cannot be transmitted to the output shaft 74. As a result, the mechanical compression ratio may not be reduced.

  The internal combustion engine of the present embodiment includes an abnormality detection device that detects such an abnormality of the clutch 70. The abnormality detection device detects that the transmission of the rotational force of the clutch 70 is abnormal when the eccentric shaft 57 is rotated in one rotational direction. In the present embodiment, the first operation control is performed when the abnormality detection device detects an abnormality of the clutch 70. In the first operation control, the eccentric shaft 57 is rotated in the other rotation direction beyond the moving range of the eccentric shaft 57 indicated by the arrow 106 in FIG. 6, thereby reducing the mechanical compression ratio to a low compression ratio. That is, the drive motor 59 is driven in the rotational direction that increases the mechanical compression ratio during normal operation.

  FIG. 13 is a first schematic cross-sectional view of clutch 70 when the first operation control in the present embodiment is performed. In the first operation control, the input shaft 71 is rotated in the direction indicated by the arrow 102. At this time, since the rotation direction of the output shaft 74 is a direction in which the wedge effect of the roller 80 is eliminated, the output shaft 74 can also be rotated in the direction indicated by the arrow 102. Even when the holding portion 73 is worn or when a foreign object is caught between the roller 80 and the outer ring 77, the holding portion 73 can be rotated in the direction indicated by the arrow 102.

  When the internal combustion engine has a medium mechanical compression ratio, the mechanical compression ratio increases immediately after the first operation control is started. When the drive motor 59 is driven to rotate the eccentric shaft 57 in the other rotation direction indicated by the arrow 69, the eccentric shaft 57 reaches the lowermost portion as shown in FIG. At this time, the volume of the combustion chamber 5 is minimized and the mechanical compression ratio is maximized. In the first operation control, the rotation is further continued in the direction indicated by the arrow 69.

  FIG. 14 is a schematic cross-sectional view of the variable compression ratio mechanism when the eccentric shaft 57 is rotated in the other rotation direction in the first operation control. Even after the mechanical compression ratio becomes maximum, when the eccentric shaft 57 is rotated in the other rotational direction as indicated by an arrow 69, the link mechanism of the variable compression ratio mechanism is reversed. The link state of the center a of the circular cam 58, the center b of the eccentric shaft 57, and the center c of the circular cam 56 is reversed. That is, referring to FIGS. 4 and 14, the position of the center b of the eccentric shaft 57 is changed from the position toward the inside of the cylinder block 2 to the position toward the outside of the cylinder block 2.

  In this state, if the rotation of the eccentric shaft 57 continues in the other rotation direction indicated by the arrow 69, the cylinder block 2 moves away from the crankcase 1. The mechanical compression ratio decreases. Referring to FIGS. 11 and 13, a force is acting on the output shaft 74 of the clutch 70 in the direction indicated by the arrow 100 during the normal operation, but in the first operation control, the link mechanism is reversed. A force is applied to the output shaft 74 in the direction indicated by the arrow 104. That is, the direction of the force acting on the output shaft 74 is reversed. The direction of the rotational force of the drive motor 59 coincides with the direction of the rotational force received from the crankcase 1. For this reason, the mechanical compression ratio can be quickly reduced.

  In the first operation control of the present embodiment, the rotation of the input shaft 71 by the drive motor 59 is continued until the mechanical compression ratio becomes the minimum state. That is, as shown in FIG. 3, the eccentric shaft 57 is moved until the eccentric shaft 57 rises most. Thereafter, in the first operation control, the variable compression ratio mechanism is maintained in a state where the mechanical compression ratio is minimum, that is, in a state where the combustion chamber 5 is maximum.

  By shifting to a state where the mechanical compression ratio becomes low, abnormal combustion such as knocking can be suppressed. Even if the state of low mechanical compression ratio is maintained, the output of the internal combustion engine can be increased by increasing the intake air amount and the fuel injection amount. For this reason, the operation of the internal combustion engine can be continued without causing the user to feel uncomfortable. That is, deterioration of drivability can be suppressed.

  FIG. 15 shows a flowchart of the first operation control in the present embodiment. The control shown in FIG. 15 can be performed, for example, during a period in which the control is performed in the normal operation mode in which the normal operation is performed. Here, the normal operation mode indicates a state in which the mechanical compression ratio is changed according to the operation state of the internal combustion engine. For example, in the normal operation mode, the mechanical compression ratio is selected based on the required load and the engine speed, and the variable compression ratio mechanism is driven according to the selected mechanical compression ratio.

  In step 111, a command for reducing the mechanical compression ratio is detected. Regarding the detection of the reduction command of the mechanical compression ratio, for example, the command value from the electronic control unit 30 to the drive motor 59 can be detected. Alternatively, the current value input to the drive motor 59 can be detected.

  Next, in step 112, current is supplied to the drive motor 59 to the side where the mechanical compression ratio is reduced. That is, driving of the drive motor 59 is started so that the eccentric shaft 57 rotates in one rotation direction.

  Next, in step 113, it is determined whether or not the clutch 70 is abnormal. In the present embodiment, the relative position sensor 22 and the electronic control unit 30 function as an abnormality detection device. The abnormality detection device determines whether or not the clutch 70 is unlocked. In determining whether the clutch 70 is unlocked, for example, the relative position of the cylinder block 2 with respect to the crankcase 1 is detected. If the relative position of the cylinder block 2 with respect to the crankcase 1 does not reach the commanded position even though a predetermined current is supplied to the drive motor 59, the clutch 70 is not unlocked. Can be determined.

  Alternatively, the drive motor 59 may be subjected to feedback control according to the relative position of the cylinder block 2 with respect to the crankcase 1. When the movement of the relative position is delayed with respect to the command value for the drive motor 59, the amount of current supplied within a predetermined time is increased. For example, control for increasing the duty ratio of the current supplied to the drive motor 59 can be performed. When the duty ratio of the current supplied to the drive motor 59 is large, it can be determined that there is a delay with respect to the command value. For this reason, when the duty ratio is larger than a predetermined determination value, it can be determined that the clutch is not unlocked. If the clutch is unlocked at step 113, the routine proceeds to step 114.

  In step 114, it is determined whether or not the actual mechanical compression ratio has reached the target mechanical compression ratio. The actual mechanical compression ratio can be estimated from the output of the relative position sensor 22. When the actual mechanical compression ratio has not reached the target mechanical compression ratio, the process returns to step 112, and the drive motor 59 is driven to further decrease the mechanical compression ratio. In step 114, when the actual mechanical compression ratio reaches the target mechanical compression ratio, this control is terminated.

  If it is determined at step 113 that the clutch 70 is not unlocked, the routine proceeds to step 115.

  In step 115, the drive motor 59 is driven to the side where the mechanical compression ratio increases. That is, the drive motor 59 is driven in a direction opposite to the direction in which rotation was attempted in step 112. The eccentric shaft 57 rotates in the other rotation direction. By performing this control, as shown in FIG. 14, the link mechanism of the variable compression ratio mechanism can be reversed, and the mechanical compression ratio can be lowered after the link mechanism is reversed.

  In step 116, it is determined whether or not the actual mechanical compression ratio has reached the determined mechanical compression ratio. In the present embodiment, the minimum mechanical compression ratio is set as the determination mechanical compression ratio. The variable compression ratio mechanism is driven until the mechanical compression ratio is minimized. If the actual mechanical compression ratio has not reached the determined mechanical compression ratio in step 116, the process returns to step 115 and the drive motor 59 continues to be driven. In step 116, when the actual mechanical compression ratio reaches the determined mechanical compression ratio, the process proceeds to step 117.

  In step 117, the change of the mechanical compression ratio is stopped. In the present embodiment, the drive motor 59 is stopped in a state where the cylinder block 2 is farthest from the crankcase 1, that is, in a state where the volume of the combustion chamber 5 is maximized.

  Next, in step 118, the operation mode of the internal combustion engine is shifted from the normal operation mode to an operation mode with a low mechanical compression ratio that maintains a small mechanical compression ratio. The control of the internal combustion engine in this operation mode can be set in advance and stored in the electronic control unit 30. For example, in order to maintain a low mechanical compression ratio, control can be performed to increase the intake air amount and the fuel injection amount that are supplied compared to the normal operation mode when the engine speed is low and the load is low. With this control, an output desired by the user can be obtained.

  Furthermore, when shifting to the operation mode of the low mechanical compression ratio, the user can be notified of the abnormality of the variable compression ratio mechanism. For example, a warning lamp for notifying that an abnormality has occurred in the variable compression ratio mechanism can be arranged on the driving operation panel. By turning on this warning lamp, it is possible to notify the user of an abnormality in the variable compression ratio mechanism. The user can recognize the abnormality of the variable compression ratio mechanism and request repair.

  Thus, in the present embodiment, when the abnormality of the clutch 70 is detected, the eccentric shaft 57 is rotated until the mechanical compression ratio is minimized. In a state where the mechanical compression ratio is minimized, the cylinder block 2 is disposed at a position farthest from the crankcase 1. For this reason, even if the cylinder block 2 is further separated from the crankcase 1 due to the combustion pressure inside the combustion chamber 5, this ascending force is blocked by the camshafts 54 and 55. For this reason, it can avoid that rotational force is transmitted from the output side of the clutch 70, and the further failure of the clutch 70 etc. can be suppressed. Note that the mechanical compression ratio to be shifted when a clutch abnormality is detected is not limited to the minimum value, and can be shifted to a predetermined low mechanical compression ratio.

  Further, when the first operation control is started as described above, the mechanical compression ratio may increase until the link mechanism is reversed. During the period when the mechanical compression ratio is high, it is possible to perform control to suppress the occurrence of abnormal combustion. For example, the ignition timing can be retarded. Alternatively, when a variable valve mechanism that can change the closing timing of the intake valve is disposed, the intake air amount can be reduced by changing the closing timing of the intake valve.

  Next, the second operation control in the present embodiment will be described. In the second operation control, similarly to the first operation control, it is determined whether or not the clutch 70 has returned to normal after being lowered to a preset low mechanical compression ratio. After changing to the low mechanical compression ratio, the eccentric shaft 57 is slightly rotated in the other rotation direction, and further rotated in one rotation direction, thereby determining whether or not the reverse input cutoff clutch 70 is abnormal.

  FIG. 16 shows a second schematic cross-sectional view of the clutch 70 when the first operation control in the present embodiment is performed. In the first operation control, when the drive motor 59 is driven so that the eccentric shaft 57 rotates in the other rotation direction, the input shaft 71 and the output shaft 74 rotate with respect to the outer ring 77. At this time, the clutch 70 may return to normal. For example, there is a case where the foreign matter caught between the roller 80 and the outer ring 77 is removed. In such a case, as shown in FIG. 16, the wedge effect of the roller 80 in the locking portion 86 is released. In the second operation control, it is detected that such a clutch has returned to normal, and control is performed to return the operation mode from the low mechanical compression ratio operation mode to the normal operation mode.

  FIG. 17 shows a flowchart of the second operational control in the present embodiment. Steps 111 to 118 are similar to the first operation control. In step 118, for example, as shown in FIG. 3, the mechanical compression ratio is maintained at a minimum state.

  Next, in step 119, the drive motor 59 is driven to the side where the mechanical compression ratio increases. Referring to FIG. 3, eccentric shaft 57 is slightly rotated in the direction indicated by arrow 69. The amount of movement of the eccentric shaft 57 at this time is preferably small enough so that the sensitivity to the mechanical compression ratio is within a low range.

  Next, in steps 120 and 121, the same control as in steps 112 and 113 is performed. In step 120, the drive motor 59 is driven to the side where the mechanical compression ratio decreases. In step 121, it is determined whether or not the clutch 70 is unlocked by the abnormality detection device.

  If it is determined in step 121 that the clutch 70 is unlocked, the process proceeds to step 122. In step 122, the internal combustion engine is returned to the normal operation mode, and this control is finished. If the clutch 70 is not unlocked in step 121, it can be determined that the clutch 70 cannot be recovered. In this case, the process proceeds to step 123.

  In step 123, the user is notified that an abnormality has occurred in the variable compression ratio mechanism. In the present embodiment, the warning light on the operation panel is turned on. Next, in step 124, the current low mechanical compression ratio is maintained and the operation mode of the low mechanical compression ratio is continued.

  In the present embodiment, the mechanical compression ratio is increased only once from the state where the mechanical compression ratio is minimum. However, the present invention is not limited to this form, and the increase and decrease of the mechanical compression ratio may be controlled a plurality of times. Absent. Thereafter, it may be determined whether or not the clutch is released.

  In the second operation control, it can be detected that the variable compression ratio mechanism has returned to normal. For this reason, although it can drive | operate in normal operation mode, it can drive | operate by a low mechanical compression ratio and can suppress that a fuel consumption increases. Alternatively, it is possible to prevent the user from requesting repair although the variable compression ratio mechanism has returned to normal during the period of the first operation control.

  Referring to FIG. 2, the clutch 70 in the present embodiment is disposed between the drive motor 59 and the worm 62, but is not limited to this form, and the rotational force of the drive motor 59 is applied to the eccentric shaft 57. It can arrange | position in the driving force transmission path | route which transmits. For example, the clutch 70 may be disposed between the worm wheels 63 and 64 and the cam shafts 54 and 55. In this case, a clutch is arranged for each of the camshafts 54 and 55.

  In the present embodiment, the internal combustion engine attached to the vehicle has been described as an example. However, the present invention is not limited to this embodiment, and the present invention is applied to an internal combustion engine disposed in an arbitrary device or facility. be able to.

  In the respective drawings described above, the same or equivalent parts are denoted by the same reference numerals. In each of the above-described controls, the order of the steps can be appropriately changed within a range where the function and the action are not changed. In addition, said embodiment is an illustration and does not limit invention. In the embodiment, the change shown in a claim is included.

DESCRIPTION OF SYMBOLS 1 Crankcase 2 Cylinder block 4 Piston 5 Combustion chamber 22 Relative position sensor 30 Electronic control unit 54,55 Camshaft 56,58 Circular cam 57 Eccentric shaft 59 Drive motor 60 Rotating shaft 65 Spring 70 Clutch 71 Input shaft 74 Output shaft 77 Outer ring 80 Roller 81 Spring 86 Locking part

Claims (2)

A support structure including a crankcase;
A cylinder block supported by the support structure via an eccentric shaft;
A drive unit that rotates the eccentric shaft and a clutch that is arranged in a drive force transmission path that transmits the rotational force of the drive unit to the eccentric shaft are formed so that the cylinder block moves relative to the support structure. A variable compression ratio mechanism;
An abnormality detection device for detecting an abnormality of the clutch,
The variable compression ratio mechanism has a predetermined range of movement of the eccentric shaft in normal operation, and by rotating the eccentric shaft in one direction of rotation, it moves relative to the support structure in the direction of separating the cylinder block, By rotating the eccentric shaft in the other rotation direction, it is formed to move relative to the support structure in the direction in which the cylinder block approaches.
The clutch is configured to transmit a rotational force from the input side corresponding to one rotational direction and the other rotational direction, and to block a rotational force from the output side corresponding to one rotational direction,
When the drive machine rotates the eccentric shaft in one rotation direction, when the abnormality detection device detects that the clutch is abnormal, the variable compression ratio mechanism exceeds the movement range of the eccentric shaft and the other rotation direction. An internal combustion engine characterized by rotating the eccentric shaft to move the cylinder block relative to the support structure in a direction away from the support structure and lowering the mechanical compression ratio to a preset value.   The variable compression ratio mechanism reduces the mechanical compression ratio to a preset mechanical compression ratio, and further increases the mechanical compression ratio by rotating the eccentric shaft in the other rotational direction. The internal combustion engine according to claim 1, wherein the engine is rotated in one rotational direction and the abnormality detection device determines whether or not the clutch is abnormal.

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