JP2009097449A - Variable compression ratio internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a variable compression ratio internal combustion engine capable of favorably performing the relative movement of a cylinder block and a crankcase and the sealing of a sliding surface between the cylinder block and the crankcase by a simple device constitution. <P>SOLUTION: The internal combustion engine (1) is constituted to relatively move the cylinder block (2) and the crankcase (4) along the direction of an axis CCA of a cylinder (21) by a moving mechanism (5). The moving mechanism (5) includes a pair of control shafts (51). The control shaft (51) is provided with a journal (51a)a and a cam (51b) fixed to each other to rotate in a body, and constituted to satisfy an expression of 0.5<R/L when eccentric amounts of both members are R, and the relative movement amount in the direction of the axis CCA of the cylinder block (2) and the crankcase (4) between the highest compression ratio state and the lowest compression ratio state. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a variable compression ratio internal combustion engine configured such that a compression ratio can be changed by a relative movement of a cylinder block, a cylinder head fixed to the cylinder block, and a crankcase along the axial direction of the cylinder. .

  As this type of internal combustion engine, those disclosed in, for example, Japanese Patent Application Laid-Open Nos. 2003-206871 and 2005-113839 are known. These internal combustion engines include a slide mechanism that slides the cylinder block with respect to the crankcase (which may also be referred to as a lower case). This slide mechanism is constructed between the cylinder block and the crankcase.

  Specifically, the slide mechanism includes a pair of control shafts arranged in parallel on both sides of the cylinder (since each cam has a cam, in each of the above publications, it is referred to as a “camshaft”. (However, the term “control shaft” is used in this specification to distinguish it from the “camshaft” in the valve mechanism provided in the cylinder head.) An airtight seal is provided on the sliding surface between the cylinder block and the crankcase.

  In the configuration disclosed in Japanese Patent Application Laid-Open No. 2003-206871, the control shaft is attached to a shaft portion, a cam portion fixed to the shaft portion, and rotatably to the shaft portion. And a movable bearing portion. The cam portion has a circular cam profile that is eccentric with respect to the central axis of the control shaft. This cam portion is housed in a cam housing hole formed in the cylinder block. The movable bearing portion is housed in a bearing housing hole formed in the crankcase.

  In the internal combustion engine having such a configuration, the pair of control shafts are rotated in opposite directions, so that the cylinder block slides relative to the crankcase along the axial direction. Thereby, the compression ratio is changed. Specifically, when the control shaft is rotated 180 ° from a state where the compression ratio is the lowest (hereinafter referred to as “minimum compression ratio state”), the state where the compression ratio is highest (hereinafter referred to as “highest compression ratio state”). This is referred to as a “compression ratio state”. Further, when the control shaft is rotated 90 ° from a state where the compression ratio is the lowest or highest, an intermediate compression ratio state (hereinafter referred to as “intermediate compression ratio state”) is obtained.

On the other hand, in the configuration disclosed in Japanese Patent Application Laid-Open No. 2005-113839, the control shaft has a simple configuration including the shaft portion and the cam portion. In this configuration, the pair of control shafts are rotated in the same direction while being synchronized with each other. For this reason, the cylinder block moves relative to the crankcase while drawing a semicircular locus.
JP 2003-206871 A JP 2005-1113839 A

  In the configuration disclosed in Japanese Patent Laid-Open No. 2003-206871, in order to move the cylinder block linearly along the axial direction of the cylinder, (1) it can freely rotate with respect to the shaft portion. The movable bearing portion is provided on the control shaft, and (2) the pair of control shafts are rotated in directions opposite to each other. For this reason, the apparatus configuration is complicated.

  That is, in such a configuration, there are many parts constituting the control shaft, and the structure is complicated. Moreover, in this structure, the said cylinder block and the said crankcase will be in the state connected via the multilink mechanism by a pair of said control shaft. For this reason, the cylinder block may swing with respect to the crankcase. When such a swing occurs, the cylinder block and the crankcase collide with generation of combustion pressure, and there is a risk that a loud striking sound is generated. Therefore, in order to achieve smooth relative movement in the axial direction between the cylinder block and the crankcase, the width direction (the direction perpendicular to the axial direction and perpendicular to the central axis of the control shaft) is used. A separate guide means for regulating the position of the cylinder block is required.

  On the other hand, in the configuration disclosed in Japanese Patent Application Laid-Open No. 2005-113839, the structure of the control shaft is simplified. For this reason, the number of parts can be reduced. Further, the position of the cylinder block in the width direction is determined by the posture of the cam portion. Therefore, the possibility that the cylinder block swings with respect to the crankcase is reduced, and the occurrence of the hitting sound as described above can be suppressed.

  However, in such a configuration, the movement trajectory of the cylinder block is semicircular. Therefore, the minimum compression ratio state where the rotation angle of the control shaft is 0 ° or the maximum compression ratio state where the rotation angle is 180 ° is changed to the intermediate compression ratio state where the rotation angle is 90 °. In this case, the cylinder block moves greatly along the width direction. Therefore, it is difficult to ensure the airtightness of the seal on the sliding surface between the cylinder block and the crankcase.

  The present invention has been made in view of such problems. That is, an object of the present invention is to provide a variable device that can perform the relative movement between the cylinder block and the crankcase and the sliding surface between the cylinder block and the crankcase satisfactorily with a simple device configuration. It is to provide a compression ratio internal combustion engine.

  In a variable compression ratio internal combustion engine (hereinafter simply referred to as “internal combustion engine”) of the present invention, a cylinder block, a cylinder head fixed to the cylinder block, and a crankcase relatively move along the axial direction of the cylinder. Thus, the compression ratio can be changed. Specifically, this internal combustion engine includes a control shaft, a block-side support portion, and a crankcase-side support portion.

  The control shaft includes a journal portion and a cam portion. The journal portion and the cam portion are arranged so as to be aligned along the longitudinal direction of the control shaft. The journal part and the cam part are formed in a cylindrical shape. The cam portion is provided eccentric from a central axis of the journal portion (rotation central axis of the control shaft: parallel to the longitudinal direction). The cam portion is coupled to the journal portion so as to rotate integrally with the journal portion. Specifically, for example, the cam portion may be formed integrally with the journal portion. Alternatively, for example, the cam portion may be fixed to the journal portion. The cam portion may be provided so as to protrude from the journal portion.

  Here, in the internal combustion engine, the pair of control shafts are provided in parallel to each other on both sides of the cylinder block. These control shafts are configured and arranged such that all the cam portions are directed in the same direction by being rotationally driven in the same direction.

  The control shaft may further comprise a worm wheel. The worm wheel is a disc-shaped gear and is provided coaxially with the central axis. The worm wheel is coupled to the journal portion so as to rotate integrally with the journal portion. In this case, the internal combustion engine includes a drive shaft and a pair of worms. The drive shaft is disposed to be orthogonal to each of the pair of control shafts. The worm is a cylindrical gear having a helical tooth shape that meshes with the worm wheel, and is fixed to the drive shaft so as to rotate integrally with the drive shaft. The pair of worms are provided at positions corresponding to the worm wheels in the pair of control shafts. Further, the tooth shape of the pair of worms is formed in a spiral shape in the same direction. That is, the pair of worms have the same tooth profile and are formed so that the pair of worm wheels can be rotated in the same direction.

  The block side support portion is provided on the cylinder block side. The crankcase side support portion is provided on the crankcase side. One of the cam portion and the journal portion is accommodated while being rotatably supported by the block side support portion and the other by the crankcase side support portion.

The present invention is characterized by the following configuration: the control shaft is configured such that the eccentricity between the journal portion and the cam portion is R, and the cylinder block between the highest compression ratio state and the lowest compression ratio state When the relative movement amount in the axial direction with the crankcase (hereinafter referred to as the maximum lift amount) is L,
It is configured so that 0.5 <R / L. Here, the control shaft is
Preferably, it is configured to satisfy 0.7 ≦ R / L ≦ 1.3,
More preferably, it is configured to satisfy 0.8 ≦ R / L ≦ 1.2,
More preferably, it may be configured such that 0.9 ≦ R / L ≦ 1.1.

  In the internal combustion engine of the present invention having such a configuration, when the compression ratio is changed, the pair of control shafts rotate in the same direction while being synchronized with each other so that all the cam portions are directed in the same direction. Is done. For example, when the drive shaft is rotationally driven by a motor or the like, a pair of worms having helical tooth shapes in the same direction rotate in the same direction. Then, each of the worm wheels facing the worms rotates in the same direction while being synchronized with each other. Accordingly, the pair of control shafts rotate in the same direction while being synchronized with each other.

  In this way, when the pair of control shafts rotate in the same direction, each of the cam portions rotates so as to move on an arc-shaped track centering on the central axis of the control shaft. As a result, the cylinder block draws an arc-shaped trajectory, with respect to the crankcase, in the axial direction and the width direction (a direction perpendicular to the axial direction and perpendicular to the central axis of the control shaft). Relative movement along. And the position of the said cylinder block in the said axial direction and the said width direction is determined by the attitude | position of the said cam part.

  Here, a state in which the directing direction of the cam portion is the width direction, that is, a state in which the eccentric direction of the cam portion is the width direction is defined as an intermediate compression ratio state. At this time, the rotation angle of the control shaft is set to 0 °. Further, when the control shaft is rotated from the intermediate compression ratio state (rotation angle θ = 0 °) to the predetermined direction by the angle θ1 (<90 °), the control shaft enters the maximum compression ratio state, and the control shaft is opposite to the predetermined direction. In the direction of the angle θ2 = θ1 is assumed to be the lowest compression ratio state (in the configuration of the present invention, there may be a case where θ2 ≠ θ1. In this case, the state where θ = 0 is Strictly speaking, it is not an intermediate value between the highest compression ratio and the lowest compression ratio, but even if θ2 ≠ θ1, for convenience, the compression ratio when θ = 0 is the difference between the highest compression ratio and the lowest compression ratio. Therefore, the state of θ = 0 can be referred to as an “intermediate compression ratio state”.

At this time, the cylinder block moves L / 2 in the axial direction from the intermediate compression ratio state to the highest compression ratio state or the lowest compression ratio state. At this time, the movement amount δ in the width direction of the cylinder block is as follows.
δ = R (1-cos θ) = R− (4R ² −L ² ) ^1/2 / 2.

  In the conventional configuration (Japanese Patent Laid-Open No. 2005-113839: R = L / 2), δ = L / 2. On the other hand, in the present invention, for example, R = 0.7L and δ is approximately 0.21L, R = 0.8L and δ is approximately 0.18L, R = 0.9L and δ is approximately 0. 15L, δ is approximately 0.13L when R = L, δ is approximately 0.12L when R = 1.1L, δ is approximately 0.11L when R = 1.2L, and δ when R = 1.3L. = 0.1L. Thus, according to the configuration of the present invention, the relative movement amount of the cylinder block in the width direction with respect to the crankcase is considerably smaller than the relative movement amount in the axial direction. That is, the relative movement of the cylinder block with respect to the crankcase is performed substantially along the axial direction.

  Here, the maximum lift amount L is usually several mm or about 5 to 6 mm. Therefore, in the conventional configuration, the relative movement amount in the width direction has reached 1 to 3 mm, but in the present invention, even if the maximum lift amount is increased to about 5 to 6 mm, The relative movement amount can be considerably smaller than the conventional one (less than 1 mm, for example, about 0.5 mm).

  Therefore, according to the present invention, with a simple device configuration, the cylinder block and the crankcase are favorably sealed while the sliding movement between the cylinder block and the crankcase is well performed. Can be broken.

  The internal combustion engine may further include a movement amount restriction unit. The movement amount restricting portion is configured to be able to restrict the relative movement amount between the cylinder block and the crankcase. The movement amount restricting portion may be configured to restrict the movement range of the cylinder block or the rotation range of the control shaft (such as the rotation range of the worm wheel).

  Specifically, the movement amount restricting portion may include a stopper member. The stopper member may be provided on the crankcase side so as to face the side surface of the cylinder block. In this case, the stopper member is configured to be able to regulate a relative movement amount between the cylinder block and the crankcase by contacting the side surface of the cylinder block.

  In this configuration, the stopper member abuts against the side surface of the cylinder block, so that the relative movement amount between the cylinder block and the crankcase is regulated, and the maximum compression ratio state and the minimum compression ratio state are defined. Is done. Therefore, the highest compression ratio state and the lowest compression ratio state can be defined by a simple device configuration.

  The movement amount restricting portion may further include a stopper support portion. The stopper support portion is attached to the crankcase. The stopper support portion is configured to support the stopper member and to move the stopper member in a direction approaching the side surface or in a direction away from the side surface. That is, the stopper support portion is configured to be able to adjust the position of the stopper member along the width direction.

  In such a configuration, the position of the stopper member can be adjusted along the width direction by the stopper support portion. Thereby, the position of the cylinder block that is in the maximum or minimum compression ratio state can be easily adjusted by a simple device configuration.

  The internal combustion engine may include a driving force output unit, a relay unit, and an engagement state adjustment unit. The driving force output unit is coupled to the crankshaft so as to rotate integrally with a crankshaft rotatably supported by the crankcase. The relay unit is configured to be able to transmit a rotational driving force by engaging with the driving force output unit. The relay unit is configured to transmit the rotational driving force transmitted from the driving force output unit to a valve mechanism provided in the cylinder head. The engagement state adjusting unit is configured to adjust the engagement state between the driving force output unit and the relay unit.

  Here, (1) the relay unit may be configured to directly engage with the driving force output unit. That is, for example, the driving force output unit and the relay unit may include disk-shaped gears. In this case, the gear of the driving force output unit and the gear of the relay unit are arranged to mesh with each other. The engagement state adjustment unit includes a support plate and an urging spring, and adjusts a contact state (engagement state) between the gear of the driving force output unit and the gear of the relay unit. Can be configured to. The support plate is configured to rotatably support the gear of the relay unit. The support plate is supported by the cylinder block so as to be swingable. In other words, the relay portion is swingably and rotatably supported by the cylinder block. Further, the support plate is urged by the urging spring so that the gear of the relay portion abuts on (engages with) the gear of the driving force output portion. Alternatively, (2) the relay unit may be configured to be coupled (indirectly engaged with the driving force output unit) to the driving force output unit via an intermediate medium such as a belt or a chain.

  In such a configuration, in order to change the compression ratio, even when the cylinder block moves relative to the crankcase so as to draw an arcuate locus, the driving force output unit and the relay unit The engagement state can be adjusted appropriately. Therefore, power transmission from the driving force output unit to the valve operating mechanism can be satisfactorily performed via the relay unit.

  Here, the engagement state adjusting unit may include a first guide unit and a second guide unit. The first guide portion is provided on the crankcase side and is configured to have a cylindrical surface. The second guide portion is provided on the support plate side so as to contact the surface of the first guide portion. The second guide part is configured to perform the following function by contacting the surface: so that the relay part moves on a substantially arc-shaped track following the shape of the surface. The second guide part guides relative movement of the relay part with respect to the driving force output part. The second guide part adjusts the contact state between the driving force output part and the relay part.

  In this configuration, when the compression ratio is changed, the cylinder block moves relative to the crankcase so as to draw an arcuate locus. Then, the relay part also moves around the driving force output part so as to draw a substantially arc-shaped locus following the shape of the surface of the second guide part. Thereby, the contact state of the driving force output unit and the relay unit is adjusted. Therefore, according to this structure, the excessive press with the said driving force output part and the said relay part is avoided favorably. Moreover, the engagement state (meshing state between gears) before and after the change of the compression ratio can be kept substantially constant. Therefore, power transmission from the driving force output unit to the valve operating mechanism via the relay unit can be performed better.

  Hereinafter, embodiments of the present invention (embodiments that the applicant considers best at the time of filing of the present application) will be described with reference to the drawings.

  In addition, the description about the following embodiment is specific to the extent possible, merely an example of the embodiment of the present invention in order to satisfy the description requirement (description requirement / practicability requirement) of the specification required by law. It is only what is described in. Therefore, as will be described later, it is quite natural that the present invention is not limited to the specific configurations of the embodiments described below. Modifications to the embodiments are listed together at the end, as they are inserted during the description of the embodiments, preventing understanding of the consistent description of the embodiments.

<Configuration of Internal Combustion Engine of First Embodiment>
FIG. 1 is a side sectional view showing a schematic configuration of an engine 1 which is a first embodiment of a variable compression ratio internal combustion engine of the present invention. FIG. 2 is a side view showing a schematic configuration of the engine 1 shown in FIG. FIG. 3 is an exploded perspective view of the engine 1 shown in FIGS. 1 and 2. In FIG. 1 and FIG. 2, it is assumed that the intermediate compression ratio state is shown.

  Referring to FIGS. 1 to 3, the engine 1 of the present embodiment includes a cylinder block 2, a cylinder head 3, a crankcase 4, a moving mechanism 5, and a driving force transmission mechanism 6. The engine 1 moves the cylinder block 2 and the cylinder head 3 with respect to the crankcase 4 along the engine height direction (direction parallel to the cylinder center axis CCA: corresponding to the axial direction of the present invention) by the moving mechanism 5. The compression ratio can be changed by relatively moving (sliding).

<< Cylinder block >>
The cylinder block 2 is a substantially rectangular and substantially rectangular parallelepiped member in plan view, and is integrally formed of an aluminum alloy. The outer surface 20 a of the cylinder block 2 is formed as a smooth surface as much as the inner surface of the cylinder 21. The cylinder 21 is a substantially cylindrical through hole. In the present embodiment, a plurality (four in the present embodiment) of cylinders 21 are provided in a line along the cylinder arrangement direction AD. The cylinder block 2 is formed to have a longitudinal direction parallel to the cylinder arrangement direction AD (see FIG. 3). Inside the cylinder 21, a piston 22 is accommodated so as to be capable of reciprocating along a cylinder center axis CCA perpendicular to the cylinder arrangement direction AD.

<< Cylinder head >>
A cylinder head 3 is joined to the upper end surface of the cylinder block 2. The cylinder head 3 is integrally formed of an aluminum alloy. The cylinder head 3 is fixed to the cylinder block 2 so as to cover the top dead center side end (the upper end in the figure) of the piston 22 in the cylinder 21. That is, the cylinder head 3 is fixed to the upper end portion of the cylinder block 2 with a bolt (not shown) or the like so as not to move relative to the cylinder block 2 (moves up and down together with the cylinder block 2). .

  A plurality of recesses are formed in the cylinder head 3. Each recess is provided at a position corresponding to each cylinder 21. A combustion chamber CC is formed by the recess and the space inside the cylinder 21 above the top surface of the piston 22. The cylinder head 3 is provided with an intake port 3a and an exhaust port 3b so as to communicate with the combustion chamber CC.

  Further, the cylinder head 3 is provided with a valve mechanism 30. Referring to FIGS. 1 and 2, the valve mechanism 30 includes an intake valve 31, an exhaust valve 32, an intake camshaft 33, and an exhaust camshaft 34. The intake valve 31 is configured and arranged so that the intake port 3 a can be opened and closed according to the rotation angle of the intake camshaft 33. The exhaust valve 32 is configured and arranged so that the exhaust port 3b can be opened and closed according to the rotation angle of the exhaust camshaft 34.

<< Crankcase >>
1 to 3 again, the crankcase 4 is integrally formed of an aluminum alloy. The crankcase 4 in the present embodiment is configured to accommodate the cylinder block 2 inside thereof. Specifically, a frame 41 is provided on the upper part of the crankcase 4. The frame 41 is a cylindrical member having an axial direction along the engine height direction, and is formed to have a longitudinal direction parallel to the cylinder arrangement direction AD. A cylinder block housing portion 41 a is formed inside the frame 41. The cylinder block accommodating portion 41a is a substantially rectangular space provided in a plan view so as to accommodate the cylinder block 2, and is provided along the engine height direction.

  An inner wall surface 41a1 (hereinafter also referred to as “an inner wall surface 41a1 of the frame 41”) of the cylinder block housing portion 41a is provided so as to face the outer surface 20a of the cylinder block 2. The inner wall surface 41a1 is also formed as a smooth surface, like the outer surface 20a of the cylinder block 2. Between the outer surface 20a of the cylinder block 2 and the inner wall surface 41a1 of the frame 41, the cylinder block 2 is in a circle in a plane perpendicular to the cylinder arrangement direction AD in the cylinder block housing portion 41a by the operation of the moving mechanism 5. A clearance of about several millimeters is provided so that it can move on the arcuate track.

  An oil seal 42 is attached to the upper end portion of the frame 41 so as to suppress leakage of oil mist from the above-described clearance. The oil seal 42 is made of a hard rubber plate that can be elastically deformed and has a smooth flat surface, and is formed in a convex shape toward the outer surface 20 a of the cylinder block 2. The oil seal 42 is configured so that the oil mist can be prevented from leaking by the surface of the above-described convex portion being in close contact with the outer surface 20a of the cylinder block 2 while being elastically pressed. The oil seal 42 is elastically deformed with the movement of the cylinder block 2 in the engine width direction (cylinder arrangement direction AD and the direction orthogonal to the engine height direction: the left-right direction in FIG. 1) accompanying the change of the compression ratio. Thus, the surface of the above-described convex portion is configured to be in close contact with the outer surface 20a of the cylinder block 2 at all times.

  A crankshaft 43 is rotatably supported at the lower end of the crankcase 4. The crankshaft 43 is disposed in parallel with the cylinder arrangement direction AD. The crankshaft 43 is connected to the piston 22 via a connecting rod 44 so as to be rotationally driven based on a reciprocating motion along the cylinder central axis CCA of the piston 22.

<< Movement mechanism >>
A moving mechanism 5 is provided on both side walls along the cylinder arrangement direction AD of the frame 41 and in the vicinity thereof. The moving mechanism 5 includes a pair of control shafts 51. The pair of control shafts 51 are provided in parallel to each other on both sides of the cylinder block 2. The moving mechanism 5 has the following configuration so that the cylinder block 2 can be moved along an arcuate orbit in a plane orthogonal to the cylinder arrangement direction AD by the rotation of the pair of control shafts 51. Yes.

<<< Control shaft >>>
FIG. 4 is a perspective view of the control shaft 51 shown in FIGS. 1 and 3. Referring to FIG. 1, FIG. 3, and FIG. 4, the control shaft 51 includes a journal portion 51a, a circular cam portion 51b, and a worm wheel 51c. The journal portion 51a, the circular cam portion 51b, and the worm wheel 51c are arranged so as to be aligned along the longitudinal direction of the control shaft 51 (the direction indicated by the one-dot chain line in FIG. 4). The control shaft 51 is configured such that the journal portion 51a, the circular cam portion 51b, and the worm wheel 51c rotate integrally. That is, the journal part 51a, the circular cam part 51b, and the worm wheel 51c are integrally coupled to each other.

  The journal portion 51a is a cylindrical member, and is provided coaxially with the rotation center axis of the control shaft 51 (corresponding to the “center axis” of the present invention). The journal portions 51 a are provided between the adjacent circular cam portions 51 b and at both ends in the longitudinal direction of the control shaft 51. The rotation center axis is provided so as to be parallel to the cylinder arrangement direction AD and orthogonal to the cylinder center axis CCA, and is indicated by a one-dot chain line in FIG.

  The circular cam portion 51b is provided so as to protrude from the journal portion 51a at a position corresponding to the cylinder 21. Specifically, the circular cam portion 51 b is a columnar member having a diameter larger than that of the journal portion 51 a and is provided eccentric from the rotation center axis of the control shaft 51. The pair of control shafts 51 are configured and arranged so that all the circular cam portions 51b are directed (projected) in the same direction by being rotationally driven in the same direction.

In the present embodiment, the control shaft 51 in this embodiment has an eccentric amount R between the journal portion 51a and the circular cam portion 51b, and the maximum lift amount of the cylinder block 2 (the maximum movement of the cylinder block 2 in the engine height direction). When the amount is L,
It is configured such that 0.9 ≦ R / L ≦ 1.1. Specifically, the control shaft 51 is configured such that the amount of eccentricity is substantially equal to the maximum lift amount. In the present embodiment, as shown in FIG. 1, the pair of control shafts 51 are configured and arranged so that the protruding direction of the circular cam portion 51b is parallel to the engine width direction in the intermediate compression ratio state. Has been.

  A worm wheel 51 c is provided at a substantially central portion in the longitudinal direction of the control shaft 51. The worm wheel 51 c is a disc-shaped gear and is provided coaxially with the rotation center axis of the control shaft 51.

<<< Control Shaft Drive >>>
Referring to FIGS. 1 and 3, the moving mechanism 5 further includes a drive shaft 52, a motor 53, and a pair of worms 54.

  The drive shaft 52 is provided in parallel with the engine width direction so as to be orthogonal to each of the pair of control shafts 51. One end (left end in the figure) of the drive shaft 52 is connected to the motor 53. That is, the drive shaft 52 is configured and arranged so as to be rotationally driven by the motor 53. In the present embodiment, the motor 53 is electrically connected to an electronic control unit (ECU). That is, the motor 53 is configured such that the rotation angle and its origin can be detected by an ECU, an encoder, and the like. The rotation angle of the motor 53 is controlled by the ECU so that a predetermined compression ratio range is realized within a range where the outer surface 20a of the cylinder block 2 and the inner wall surface 41a1 of the frame 41 do not collide directly. Has been.

  A pair of worms 54 are provided at both ends of the drive shaft 52. The worm 54 is a cylindrical gear having a helical tooth shape that meshes with the worm wheel 51 c, and is fixed to the drive shaft 52 so as to rotate integrally with the drive shaft 52. The pair of worms 54 are provided at positions corresponding to the pair of worm wheels 51c. The pair of worms 54 has a tooth shape formed in a spiral shape in the same direction. That is, the tooth profile of the pair of worms 54 is formed to be the same so that the pair of worm wheels 51c rotate in the same direction by the rotation of the drive shaft 52.

<<< Block side support part >>>
Referring to FIGS. 1 and 3, the cylinder block 2 is provided with a block side support portion 55. The block side support portion 55 is disposed at a position corresponding to the circular cam portion 51b. That is, the plurality of block side support portions 55 are provided so as to correspond to the cylinder 21.

  A bearing hole 55 a is formed in the block side support portion 55. The bearing hole 55a is a through hole having an inner diameter corresponding to the outer diameter of the circular cam portion 51b (so that it can slide on the surface of the circular cam portion 51b). That is, the circular cam portion 51 b is accommodated while being rotatably supported by the block side support portion 55.

<<< Crankcase side support part >>>
The frame 41 is provided with the same number of openings 56 as the block side support portions 55. The opening 56 is a hole provided so as to penetrate the side wall along the cylinder arrangement direction AD of the frame 41, and is a block side support that moves together with the cylinder block 2 while drawing the arc-shaped locus as described above. The portion 55 is formed so as to be accommodated.

  A plurality of frame side support portions 57 are formed on the frame 41. Each frame-side support portion 57 is provided so as to be adjacent to the opening portion 56. That is, the plurality of frame side support portions 57 are provided on both sides of each opening portion 56 and are arranged along the cylinder arrangement direction AD. These frame side support portions 57 are provided outside the frame 41 (on the side opposite to the inner wall surface 41a1). The frame side support portion 57 is provided with a journal support recess 57a. The journal support recess 57a is a recess having a shape corresponding to a semi-cylindrical shape and is formed to have an inner diameter corresponding to the outer diameter of the journal portion 51a.

  A cover portion 58 is attached to the frame 41. The cover portion 58 is provided so as to face the frame side support portion 57 with the journal portion 51 a of the control shaft 51 interposed therebetween. The cover portion 58 is airtightly joined to the frame 41 from the outside so that leakage of oil mist from the opening 56 provided in the frame 41 to the outside of the engine 1 can be suppressed. The cover portion 58 is configured to be mounted on the frame side support portion 57 so as to rotatably support the control shaft 51 (journal portion 51a) together with the frame side support portion 57 (illustrated in FIG. 1). The cover portion 58 is not shown for the sake of clarity.)

  The cover portion 58 is formed integrally (seamlessly) so as to correspond to the plurality of frame-side support portions 57 arranged along the cylinder arrangement direction AD. The cover portion 58 is formed with a journal support recess 58a, a bearing housing portion 58b, and a worm wheel housing portion 58c.

  The journal support recess 58a is a semi-cylindrical recess symmetrical to the journal support recess 57a of the frame side support 57, and is provided to face the journal support recess 57a. That is, the journal portion 51a is rotatably supported by the bearing hole formed by the journal support recess 58a and the journal support recess 57a. As described above, in the configuration of the present embodiment, the journal block 51a is rotatably supported by the frame 41 and the cover 58, so that the cylinder block 2 is connected to the crankcase 4 (frame 41) via the control shaft 51. It is supported by.

  The bearing housing portion 58 b is a recess provided at a position facing the block side support portion 55. The bearing accommodating portion 58b is formed so as to accommodate the block-side support portion 55 that passes through the opening 56 and protrudes to the outside of the frame 41 and moves on the arcuate track as described above. The worm wheel accommodating portion 58c is a recess provided at a position facing the worm wheel 51c. The worm wheel accommodating portion 58c is formed so as to accommodate the worm wheel 51c protruding to the outside of the frame 41.

<< driving force transmission mechanism >>
Referring to FIG. 2, the driving force transmission mechanism 6 is configured as follows so that the rotational driving force generated in the crankshaft 43 can be transmitted to the valve mechanism 30 provided in the cylinder head 3. Has been.

  The output gear 61 as a driving force output unit of the present invention is a disc-shaped gear, and is coupled to the end of the crankshaft 43 so as to rotate integrally with the crankshaft 43. The intake timing wheel 62 and the exhaust timing wheel 63 are disk-shaped pulleys, and are configured to be rotationally driven by a timing belt 64. The intake timing wheel 62 is coupled to the end of the intake camshaft 33 so as to rotate integrally with the intake camshaft 33. Similarly, the exhaust timing wheel 63 is coupled to the end of the exhaust camshaft 34 so as to rotate integrally with the exhaust camshaft 34.

  The relay portion 65 is configured to be able to transmit a rotational driving force from the crankshaft 43 by directly engaging with the output gear 61. The relay unit 65 is configured to be able to transmit the rotational driving force transmitted from the output gear 61 to the valve mechanism 30 provided in the cylinder head 3 via the timing belt 64. Specifically, the relay unit 65 includes a relay gear 65a and a relay wheel 65b. The relay gear 65 a is a disc-shaped gear and is configured to mesh with the output gear 61. The relay wheel 65 b is a disc-shaped pulley and is configured to be able to rotationally drive the intake timing wheel 62 and the exhaust timing wheel 63 via the timing belt 64. The relay gear 65a and the relay wheel 65b are disposed coaxially and are coupled to each other so as to rotate integrally.

<<< engagement state adjustment section >>>
The driving force transmission mechanism 6 in the present embodiment is also an engagement state adjustment unit of the present invention that can adjust the engagement state of the output gear 61 with the relay unit 65 (engagement state with the relay gear 65a). The following configuration is provided.

  The relay portion 65 is rotatably supported at one end portion of the support plate 66. That is, a support shaft 66 a provided at one end of the support plate 66 is inserted through the through hole provided along the rotation center axis of the relay portion 65. On the other hand, a through hole is formed in the other end portion of the support plate 66 along a direction parallel to the crankshaft 43. A rocking shaft 66b erected from the cylinder block 2 is inserted into the through hole. That is, the support plate 66 is supported by the cylinder block 2 so as to be able to swing around the swing shaft 66b.

  A biasing spring 67 is provided at the fixed end of the support plate 66 (on the rocking shaft 66b side). The urging spring 67 is a torsion spring, and is configured and arranged so as to urge the free end portion of the support plate 66 (one end portion where the relay portion 65 is supported) in the direction of the output gear 61. That is, the urging spring 67 is configured to urge the support plate 66 in the above-described direction so that the relay portion 65 is brought into contact with the output gear 61 (so that the relay gear 65a is engaged with the output gear 61). Has been. Specifically, the urging spring 67 is supported by the oscillating shaft 66b by inserting a coil-shaped portion that is a main body portion thereof through the oscillating shaft 66b. A fixed arm 67 a that is one arm portion of the urging spring 67 is fixed to the cylinder block 2. On the other hand, the swing arm 67b, which is the other arm portion of the biasing spring 67, is fixed to the support plate 66 so as to bias the support plate 66 in the above-described direction.

  The crankcase 4 is provided with a guide plate 68a as a first guide portion of the present invention. The guide plate 68a is disposed so as to face the center portion in the longitudinal direction of the support plate 66 and the end portion in the width direction. The guide plate 68 a is arranged in a direction in which the support plate 66 is urged by the urging spring 67. The guide surface 68a1 is a surface of the guide plate 68a on the side facing the support plate 66. The guide surface 68a1 is formed in a cylindrical surface so that the distance between the centers of the output gear 61 and the relay gear 65a is constant even when the cylinder block 2 moves relative to the crankcase 4.

  A guide roller 68 b as a second guide portion of the present invention is supported on the support plate 66 so as to be rotatable about an axis parallel to the crankshaft 43. The guide roller 68b is provided so as to face the guide plate 68a. Specifically, the guide roller 68b is provided at the center of the support plate 66 in the longitudinal direction, that is, at an intermediate position between the support shaft 66a and the swing shaft 66b. The guide roller 68b is provided at an end portion on the guide plate 68a side (end portion on the crankshaft 43 side) in the width direction of the support plate 66. Further, the guide roller 68b is provided so as to protrude from the support plate 66 so as to contact the guide surface 68a1.

  The guide plate 68a and the guide roller 68b are arranged so that the relay portion 65 moves on an arc-shaped track in a side view centered on the central axis of the output gear 61 (rotation central axis of the crankshaft 43). By guiding the movement, the contact state between the output gear 61 and the relay portion 65 is adjusted. In the present embodiment, the guide plate 68a and the guide roller 68b are arranged so that the guide roller 68b is positioned at a substantially central portion in the engine height direction of the guide plate 68a in the intermediate compression ratio state.

<Variable compression ratio operation>
Hereinafter, the outline of the compression ratio changing operation in the engine 1 of the present embodiment will be described with reference to FIGS. 1 to 4 and other drawings as necessary.

  In the intermediate compression ratio state, as shown in FIG. 1, the protruding direction of the circular cam portion 51b is parallel to the engine width direction. At this time, the relative position of the cylinder block 2 with respect to the crankcase 4 (frame 41) is the most biased position in the engine width direction. Further, as shown in FIG. 2, the guide roller 68b is located at a substantially central portion in the engine height direction of the guide plate 68a.

  When the compression ratio is changed from the intermediate compression ratio state shown in FIGS. 1 and 2, the motor 53 is activated and the worm 54 is driven to rotate. Then, the pair of worm wheels 51c rotate in synchronization with the same direction. By the rotation of the pair of worm wheels 51c, the pair of control shafts 51 rotate in synchronization with the same direction.

  Due to the rotation of the pair of control shafts 51, the journal portion 51a is formed into a bearing hole on the crankcase 4 side (this is formed by the journal support recess 57a of the frame side support portion 57 and the journal support recess 58a of the cover portion 58). Of the control shaft 51 around the rotation center axis. At this time, the journal portion 51a does not move relative to the crankcase 4 in the engine width direction and the engine height direction.

  On the other hand, the circular cam portion 51 b moves on an arc-shaped track as viewed from the side with the rotation center axis of the control shaft 51 as a center by the rotation of the control shaft 51. Further, the circular cam portion 51 b rotates inside the block side support portion 55 while sliding with the inner surface of the bearing hole 55 a in the block side support portion 55. Therefore, the cylinder block 2 moves on the arc-shaped track in the side view as described above. As a result, the distance between the cylinder head 3 and the crankshaft 43 varies, and the compression ratio is changed.

  At this time, the position of the cylinder block 2 in the engine width direction and the engine height direction is determined by the rotation angle of the control shaft 51, that is, the protruding state of the circular cam portion 51b. Further, the movement of the cylinder block 2 in the frame 41 causes the clearance width between the outer surface 20a of the cylinder block 2 and the inner wall surface 41a1 of the frame 41 to vary.

  However, in the configuration of the present embodiment, as will be described later, the amount of movement of the cylinder block 2 in the engine width direction is extremely small. Therefore, even if the cylinder block 2 moves in the frame 41, the oil seal 42 is elastically deformed, and the oil seal 42 is slipped between the surface of the convex portion of the oil seal 42 and the outer surface 20a of the cylinder block 2. 42 always adheres to the outer surface 20a of the cylinder block 2. Therefore, leakage of oil mist to the outside in this clearance is satisfactorily suppressed.

<Operation / Effects of Configuration of Embodiment>
When the compression ratio is changed from the intermediate compression ratio state shown in FIGS. 1 and 2, the control shaft 51 rotates counterclockwise in the drawing. As a result, the cylinder block 2 moves from the state shown in FIG. 1 upward and to the left in the drawing, as shown in FIGS. On the other hand, when the compression ratio is changed to be higher from the above-described intermediate compression ratio state, the control shaft 51 rotates clockwise in the figure. As a result, the cylinder block 2 moves from the state shown in FIG. 1 downward and leftward in the figure, as shown in FIGS.

Here, FIG. 5 and FIG. 6 show the minimum compression ratio state. 7 and 8 show the maximum compression ratio state. Further, it is assumed that the rotation angle of the control shaft 51 from the intermediate compression ratio state to the lowest compression ratio state is equal to the rotation angle of the control shaft 51 from the intermediate compression ratio state to the highest compression ratio state. In this case, in the lowest or highest compression ratio state, the circular cam portion 51b, that is, the position of the cylinder block 2 moves L / 2 upward or downward from the intermediate compression ratio state as shown in FIGS. And move to the left by δ. If the rotation angle of the control shaft 51 from the intermediate compression ratio state shown in FIGS. 1 and 2 at this time is θ,
δ = R (1-cos θ), R sin θ = L / 2
Therefore, the following formula is established.
δ = R− (4R ² −L ² ) ^1/2 / 2

  FIG. 9 is a graph showing the relationship between the amount of eccentricity R and the maximum amount of movement δ in the engine width direction of the cylinder block 2 based on the above equation. In FIG. 9, the horizontal axis indicates R / L, and the vertical axis indicates δ / L. In the present embodiment, since R is substantially equal to L, δ is approximately 0.13L. Here, when the maximum lift amount is 6 mm, δ is about 0.78 mm. On the other hand, in the conventional configuration disclosed in Japanese Patent Application Laid-Open No. 2005-113839, since δ = L / 2, when the maximum lift amount is 6 mm, δ reaches 3 mm. Thus, according to the configuration of the present embodiment, the compression ratio can be changed with the amount of movement of the cylinder block 2 in the engine width direction that is much smaller than that in the prior art. That is, the amount of fluctuation in the clearance between the outer surface 20a of the cylinder block 2 and the inner wall surface 41a1 of the frame 41 is much smaller than in the past. Therefore, the seal between the outer surface 20a of the cylinder block 2 and the inner wall surface 41a1 of the frame 41 by the oil seal 42 can be satisfactorily performed. For example, the selection range of the material and characteristics (rigidity, etc.) of the oil seal 42 is expanded.

  Further, during the compression ratio changing operation as described above, the guide roller 68b moves on an arc-shaped track in a side view while abutting on the guide surface 68a1 of the guide plate 68a. Then, the relay unit 65 also moves on an arcuate track in a side view with the center axis of the output gear 61 (the rotation center axis of the crankshaft 43) as the center. Therefore, the center-to-center distance between the output gear 61 and the relay portion 65 (relay gear 65a) is kept substantially constant. That is, before and after the compression ratio change, the engagement state between the output gear 61 and the relay unit 65 (relay gear 65a) is maintained substantially constant. Thereby, noise generation at the meshing portion of the output gear 61 and the relay gear 65a can be suppressed as much as possible. Also, rapid wear due to excessive contact between the output gear 61 and the relay gear 65a can be effectively prevented.

  In the configuration of the present embodiment, as described above, the position of the cylinder block 2 in the engine width direction is determined by the rotation angle of the control shaft 51. The control shaft 51 is rotationally driven by a worm gear mechanism including a worm wheel 51c and a worm 54 provided between the control shaft 51 and a drive shaft 52 orthogonal thereto. Therefore, if the control shaft 51 is not rotationally driven by the drive shaft 52 and the worm gear mechanism described above, the cylinder block 2 is unlikely to move spontaneously in the engine width direction. Furthermore, since the cylinder block 2 is supported by the crankcase 4 via the control shaft 51, direct load transmission from the cylinder block 2 to the crankcase 4 and the cylinder block 2 and the crankcase 4 (frame 41) are supported. ) Is unlikely to occur. Therefore, according to this embodiment, generation | occurrence | production of the striking sound by the cylinder block 2 and the crankcase 4 colliding with generation | occurrence | production of combustion pressure can be suppressed effectively.

<Second Embodiment>
Next, a second embodiment of the present invention will be described. In the following description of the embodiments, components having the same configurations and functions as the components in the first embodiment described above are given the same name and the same reference numerals in this embodiment. The description of the above-described first embodiment is incorporated as appropriate within a technically consistent range (the same applies to third and subsequent embodiments and modifications described later).

  FIG. 10 is a side view (similar to FIG. 2 in the first embodiment) showing a schematic configuration of the engine 1 of the present embodiment. Referring to FIG. 10, the driving force transmission mechanism 6 in the present embodiment is configured such that the crankshaft 43 and the relay portion 65 are indirectly engaged. Specifically, in the present embodiment, an output sprocket 61 ′ is coupled to the end of the crankshaft 43 instead of the output gear 61 (see FIG. 2). Further, instead of the relay gear 65a (see FIG. 2), a relay sprocket 65a 'is provided coaxially with the relay wheel 65b, and is coupled to rotate integrally with the relay wheel 65b. An endless chain 65c is suspended between the output sprocket 61 'and the relay sprocket 65a'. That is, the crankshaft 43 and the relay portion 65 are connected via the chain 65c.

  In the present embodiment, the support plate 66 is fixed to the cylinder block 2. Further, a chain tensioner 69 is disposed in the vicinity of a portion where the chain 65c is stretched substantially linearly. The chain tensioner 69 is configured and arranged so as to bias the above-described portion of the chain 65c in a direction in which the chain 65c is wound around the output sprocket 61 'and the relay sprocket 65a'.

  According to this configuration, the same functions and effects as those of the first embodiment described above are achieved. In particular, according to the present embodiment, when the cylinder block 2 moves relative to the crankcase 4 while drawing an arcuate locus in a side view, the tension of the chain 65c is adjusted by the chain tensioner 69. Thereby, the engagement state of the crankshaft 43 and the relay part 65 is maintained favorable. Therefore, the rotational driving force of the crankshaft 43 can be satisfactorily transmitted to the valve mechanism 30 with a very simple device configuration.

<Third embodiment>
Next, a third embodiment of the present invention will be described. FIG. 11 is a side sectional view (a diagram corresponding to FIG. 1 in the first embodiment) showing a schematic configuration of the engine 1 of the present embodiment. Here, in FIG. 11, the forces received by the piston 22, the cylinder head 3, the control shaft 51, and the drive shaft 52 in the stroke in which the fuel mixture burns and expands in the combustion chamber CC are indicated by arrows. And

<< Configuration >>
In the present embodiment, the frame 41 is provided with a movement amount restricting portion 45 for restricting the relative movement amount between the cylinder block 2 and the crankcase 4. The movement amount restricting portion 45 is arranged on the side where the cylinder block 2 moves when the compression ratio is changed from the intermediate compression ratio state as shown in FIG. It is comprised so that the movement range of can be controlled.

  FIG. 12 is an enlarged side sectional view of the periphery of the movement amount restricting portion 45 shown in FIG. Referring to FIG. 11, the movement amount restricting portion 45 includes a stopper member 45a, a stopper support bolt 45b, and a lock nut 45c.

  The stopper member 45a is disposed between the outer surface 20a of the cylinder block 2 and the inner wall surface 41a1 of the frame 41, and is provided to face the outer surface 20a. The stopper member 45a is configured to be able to regulate the relative movement amount between the cylinder block 2 and the frame 41 by contacting the outer surface 20a. The stopper member 45a is fixed to the tip of the stopper support bolt 45b. That is, the stopper member 45a is supported by the stopper support bolt 45b.

  A stopper support bolt 45 b as a stopper support portion of the present invention is screwed into a screw hole formed in the frame 41. The stopper support bolt 45b is configured to be able to move the stopper member 45a in the direction approaching the outer surface 20a or in the direction separating from the outer surface 20a by changing the screwed state with respect to the frame 41. That is, the stopper support bolt 45b is configured to be able to adjust the maximum and minimum compression ratios by adjusting the position of the stopper member 45a along the engine width direction.

  A lock nut 45c is provided between the outer wall surface of the frame 41 and the head of the stopper support bolt 45b. The lock nut 45c is a nut formed to fit the thread of the stopper support bolt 45b, and is tightened so as to be in close contact with the outer wall surface of the frame 41, whereby the stopper support bolt 45b is fixed to the frame 41. The screwed state can be fixed. Further, the lock nut 45c is configured to suppress leakage of oil mist from the above-described screw hole for screwing the stopper support bolt 45b to the frame 41.

  Referring to FIG. 11 again, one end of the drive shaft 52 (the left end in the figure) is connected to the output shaft of the motor 53. The other end (right end in the figure) of the drive shaft 52 is urged by a drag spring 59 in a direction that opposes the force (see the black arrow in the figure) that the drive shaft 52 receives during the combustion / expansion stroke. (See the white arrow in the figure).

<< Operation and action / effect >>
Hereinafter, the operation, operation, and effect of the configuration of the present embodiment will be described with reference to FIGS. 11 and 12. Here, it is assumed that the intermediate compression ratio state is shown in (I-1) and (II-1) in FIG. In addition, (I-2) and (II-2) indicate the lowest and highest compression ratio states.

  While the engine 1 is stopped, the position of the cylinder block 2 is set so as to be in the intermediate compression ratio state. In this state, the outer surface 20a of the cylinder block 2 is separated from the stopper member 45a. In this state, after loosening the lock nut 45c, the screwing state of the stopper support bolt 45b to the frame 41 is changed, as shown in (I-1) and (II-1) in FIG. In addition, the position of the stopper member 45a is adjusted. For example, in order to increase the maximum lift amount to increase the maximum compression ratio and decrease the minimum compression ratio, the stopper support bolt 45b is adjusted in the pulling direction so that the position of the stopper member 45a is located outside the cylinder block 2. The direction is changed in a direction away from the side surface 20a. Then, the position of the stopper member 45a is fixed by tightening the lock nut 45c again so as to be in close contact with the outer wall surface of the frame 41.

  When the minimum or maximum compression ratio state is set during operation of the engine 1, the cylinder block 2 moves relative to the frame 41 to the left in the drawing. And when the outer side surface 20a of the cylinder block 2 contacts the stopper member 45a, the maximum amount of movement of the cylinder block 2 in the left direction in the figure is defined. Accordingly, as shown in (I-2) and (II-2) in FIG. 11, the maximum amount of lift of the cylinder block 2 or the amount of the cylinder block 2 can be increased according to the position of the stopper member 45a adjusted by the stopper support bolt 45b. A maximum descent amount is specified. In this way, the lowest or highest compression ratio state is set.

  Thus, in the configuration of the present embodiment, the minimum and maximum compression ratios are defined by the stopper member 45a. Therefore, according to the present embodiment, the minimum and maximum compression ratios can be defined with a simple device configuration.

  In the configuration of the present embodiment, the minimum and maximum compression ratios are adjusted by adjusting the position of the stopper member 45a by the stopper support bolt 45b. For example, the maximum compression ratio is adjusted by adjusting the position of the stopper member 45a by the stopper support bolt 45b so that the valve stamp does not occur. In accordance with this, the minimum compression ratio is also set. Therefore, according to this embodiment, the minimum and maximum compression ratios can be adjusted accurately and reliably with a simple device configuration. In this case, for example, in the compression ratio learning control by the ECU after the engine 1 is started, the cylinder block 2 is moved to a position where the outer surface 20a comes into contact with the stopper member 45a. It can be carried out.

  Referring to FIG. 11, in the stroke in which the fuel mixture burns and expands in the combustion chamber CC, the cylinder head 3 and the cylinder block 2 coupled thereto receive an upward force along the cylinder center axis CCA (in the drawing) See up arrow). This force is much larger than the force for lowering the cylinder block 2 and the cylinder head 3 due to the depression of the piston 22 by the combustion pressure and the dead weight of the cylinder block 2 and the cylinder head 3. Therefore, a force (moment) is generated on the control shaft 51 so as to rotate in a direction (counterclockwise in the figure) that raises the cylinder block 2 and lowers the compression ratio.

  Then, the drive shaft 52 receives a rightward force in the figure through the worm wheel 51c and the worm 54 meshing with the worm wheel 51c (see the black arrow in the figure). However, the drive shaft 52 is always biased by a drag spring 59 in a direction against this (see the white arrow in the figure). Thereby, the load in the axial direction of the drive shaft 52 is effectively reduced.

<List of examples of modification>
The above-described embodiments are merely examples of specific configurations of the present invention that the applicant considered to be the best at the time of filing of the present application, as described above. It should not be limited at all by the above-described embodiments. Therefore, it is a matter of course that various modifications can be made to the specific configurations shown in the above-described embodiments without departing from the essential part of the present invention.

  Hereinafter, some modifications will be exemplified. However, it goes without saying that the modified examples are not limited to the following. The limited interpretation of the present invention based on the description of the above-described embodiment and the following modifications unfairly harms the interests of the applicant (especially rushing the application under the principle of prior application), but improperly imitates the imitator. It is good and not allowed.

  Needless to say, the configurations of the above-described embodiments and the configurations described in the following modifications may be applied in an appropriate combination within a technically consistent range.

(1) In the above-described embodiment, the control shaft 51 has the eccentric amount R and the maximum lift amount L.
It is configured such that 0.9 ≦ R / L ≦ 1.1. Specifically, the control shaft 51 is configured such that the amount of eccentricity is substantially equal to the maximum lift amount. However, the present invention is not limited to this.

  Referring to FIG. 9, in the range of 0.5 <R / L ≦ 0.7, the maximum movement amount δ of the cylinder block 2 in the engine width direction is greatly reduced as the eccentric amount R increases. Therefore, if at least 0.5 <R / L, the predetermined effect of the present invention can be achieved. However, while it is preferable that R is large, if R is excessively large, the drive shaft 52 increases in size, and consequently the engine 1 increases in size. Therefore, in order to suppress the increase in size of the engine 1 (drive shaft 52) while further reducing δ, the control shaft 51 is configured to satisfy 0.7 ≦ R / L ≦ 1.3. It is more preferable that 0.8 ≦ R / L ≦ 1.2, and it is more preferable that 0.9 ≦ R / L ≦ 1.1.

  (2) The oil seal 42 may be fixed to both the cylinder block 2 and the frame 41. That is, the oil seal 42 is stretched between the cylinder block 2 and the frame 41, and may be configured to expand and contract as the cylinder block 2 moves relative to the crankcase 4 (frame 41). .

  (3) In the second embodiment, the support plate 66 can be omitted. That is, the relay portion 65 can be directly supported by the cylinder block 2.

  (4) In the third embodiment, the movement amount restricting portion 45 or the drag spring 59 can be omitted.

  (5) The movement amount regulating unit 45 may be provided so as to define a movement range of the cylinder block 2 in the engine height direction. That is, the movement amount restricting portion 45 may be provided so as to come into contact with the cylinder block 2 or the block side support portion 55 from above and / or below.

  (6) The stopper member 45 a may be fixed to the frame 41. That is, the position of the stopper member 45a for defining the moving range of the cylinder block 2 may be fixed.

  (7) The movement amount regulating unit 45 may be configured such that the minimum compression ratio and the maximum compression ratio can be individually adjusted. FIG. 13 is a side sectional view showing a configuration of one modified example of the movement amount regulating unit 45 shown in FIG. Referring to FIG. 13, in the present modification, the cylinder block 2 is provided with a stopper contact portion 23 so as to protrude from the outer surface 20a. Further, the movement amount restricting portion 45 includes a stopper member 45aH, a stopper support bolt 45bH, and a lock nut 45cH for defining the maximum compression ratio, and a stopper member 45aL, a stopper support bolt 45bL for defining the minimum compression ratio, and A lock nut 45cL.

  In the intermediate compression ratio state shown in FIG. 13 (II), the stopper member 45aH, the stopper support bolt 45bH, and the lock nut 45cH are provided below the stopper contact portion 23. When the compression ratio is changed to a high value from the intermediate compression ratio state, the stopper member 45aH can abut the stopper abutting portion 23 as shown in (III) so that the maximum compression ratio can be defined. It is configured.

  On the other hand, the stopper member 45aL, the stopper support bolt 45bL, and the lock nut 45cL are provided above the stopper contact portion 23. When the compression ratio is changed to a low value from the intermediate compression ratio state, the stopper member 45aL comes into contact with the stopper contact portion 23 as shown in (I) so that the minimum compression ratio can be defined. It is configured.

  In such a configuration, the minimum compression ratio and the maximum compression ratio are individually adjusted by individually adjusting the stopper support bolt 45bH and the stopper support bolt 45bL. Therefore, individual adjustment of the minimum compression ratio and the maximum compression ratio can be realized with a simple device configuration.

  As described above, the position of the stopper member 45aH and / or the stopper member 45aL may be fixed.

  (8) The movement range of the cylinder block 2 can be regulated (defined) by the rotation range of the control shaft 51, that is, the rotation range of the worm wheel 51c. Here, the restriction of the rotation range may be performed electrically by controlling the rotation angle of the motor 53 by the ECU as in the first embodiment described above, or the configuration of the worm wheel 51c and the like. May be performed mechanically.

  14A and 14B are side views showing a configuration of a modified example of the worm wheel 51c shown in FIG. For example, as shown in FIG. 14A, a gear tooth profile may be formed only on a part of the substantially circular outer periphery of the worm wheel 51c. Alternatively, as shown in FIG. 14B, the worm wheel 51c may be formed in a fan shape. Thereby, the rotation range of the control shaft 51 can be regulated by a simple device configuration.

  In this case, a worm wheel stopper 24H for defining the rotation angle on the high compression ratio side and a worm wheel stopper 24L for defining the rotation angle on the low compression ratio side may be provided. The worm wheel stopper 24 </ b> H and the worm wheel stopper 24 </ b> L come into contact with the gear tooth end of the worm wheel 51 c or the end of the fan-shaped worm wheel 51 c so that the rotation range of the worm wheel 51 c can be reliably regulated. It is configured.

  (9) Other modifications not specifically mentioned are naturally included in the technical scope of the present invention within the scope not changing the essential part of the present invention.

  For example, the present invention is applicable to gasoline engines, diesel engines, methanol engines, bioethanol engines, and any other type of internal combustion engine. The number of cylinders and the cylinder arrangement method (in-line, V-type, horizontally opposed) are not particularly limited.

  The material can be changed as appropriate. Moreover, what was one piece (one piece) can be made into another body (two piece), and vice versa. The one-piece (one-piece) one can be formed seamlessly (seamlessly), or can be formed using a joining layer by welding, adhesion, or the like.

  Furthermore, in each element constituting the means for solving the problems of the present invention, elements expressed functionally and functionally include the specific structures disclosed in the above-described embodiments and modifications, It includes any structure that can realize this action / function.

1 is a side sectional view showing a schematic configuration of an engine which is a first embodiment of a variable compression ratio internal combustion engine of the present invention. It is a side view which shows schematic structure of the engine shown by FIG. FIG. 3 is an exploded perspective view of the engine shown in FIGS. 1 and 2. FIG. 4 is a perspective view of the control shaft shown in FIGS. 1 and 3. It is a sectional side view which shows the mode of operation | movement of the engine shown by FIG. It is a sectional side view which shows the mode of operation | movement of the engine shown by FIG. It is a sectional side view which shows the mode of operation | movement of the engine shown by FIG. It is a sectional side view which shows the mode of operation | movement of the engine shown by FIG. 2 is a graph showing the relationship between the amount of eccentricity R and the maximum amount of movement δ in the engine width direction of the cylinder block 2 in the engine shown in FIG. 1. It is a side view (figure equivalent to Drawing 2 in a 1st embodiment) showing a schematic structure of an engine of a 2nd embodiment. It is a sectional side view (figure equivalent to FIG. 1 in 1st embodiment) which shows schematic structure of the engine of 3rd embodiment. It is the sectional side view which expanded the periphery of the movement amount control part shown by FIG. It is a sectional side view which shows the structure of one modification of the movement amount control part shown by FIG. It is a side view which shows the structure of the modification of the worm wheel shown by FIG. It is a side view which shows the structure of the modification of the worm wheel shown by FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Engine 2 ... Cylinder block 20a ... Outer surface 21 ... Cylinder 22 ... Piston 3 ... Cylinder head 30 ... Valve mechanism 4 ... Crankcase 41 ... Frame 41a1 ... Inner wall surface 42 ... Oil seal 43 ... Crankshaft 45 ... Movement amount regulation 45a ... Stopper member 45b ... Stopper support bolt 45c ... Lock nut 5 ... Movement mechanism 51 ... Control shaft 51a ... Journal part 51b ... Circular cam part 51c ... Worm wheel 52 ... Drive shaft 53 ... Motor 54 ... Worm 55 ... Block side support Portion 55a ... Bearing hole 56 ... Opening 57 ... Frame-side support 57a ... Journal support recess 58 ... Cover 58a ... Journal support recess 6 ... Driving force transmission mechanism 61 ... Output gear 65 ... Relay portion 65a ... Relay gear 65b ... Relay Wheel 66 ... support plate 67 ... with The spring 68a ... guide plates 68A1 ... guide surface 68b ... guide roller CC ... combustion chamber CCA ... cylinder center axis

Claims (7)

A variable compression ratio internal combustion engine configured such that a compression ratio can be changed by relative movement of a cylinder block and a cylinder head fixed to the cylinder block and a crankcase along the axial direction of the cylinder,
A control shaft comprising: a columnar journal portion; and a columnar cam portion provided eccentrically from the central axis of the journal portion and coupled to the journal portion so as to rotate integrally with the journal portion. When,
A block side support portion configured to be accommodated while rotatably supporting one of the cam portion and the journal portion, and provided on the cylinder block side;
A crankcase side support portion, which is configured to be accommodated while rotatably supporting the other, provided on the crankcase side;
With
A pair of the control shafts are provided in parallel to each other on both sides of the cylinder block, and are configured such that all the cam portions are directed in the same direction by being driven to rotate in the same direction,
The control shaft is
Let R be the amount of eccentricity between the journal portion and the cam portion, and let L denote the relative movement amount between the cylinder block and the crankcase in the axial direction between the state where the compression ratio is the highest and the state where the compression ratio is the lowest. If
A variable compression ratio internal combustion engine configured to satisfy 0.5 <R / L. The variable compression ratio internal combustion engine according to claim 1,
A variable compression ratio internal combustion engine, further comprising a movement amount restricting portion configured to restrict a relative movement amount between the cylinder block and the crankcase. A variable compression ratio internal combustion engine according to claim 2,
The movement amount regulating unit is
A stopper member provided on the crankcase side so as to face the side surface of the cylinder block;
A variable compression ratio internal combustion engine configured to be able to regulate a relative movement amount of the cylinder block and the crankcase by the stopper member coming into contact with the side surface. A variable compression ratio internal combustion engine according to claim 3,
The movement amount regulating unit is
A stopper support portion mounted on the crankcase and configured to support the stopper member and to move the stopper member in a direction approaching the side surface or in a direction away from the side surface; A variable compression ratio internal combustion engine comprising: The variable compression ratio internal combustion engine according to any one of claims 1 to 4,
A driving force output unit coupled to the crankshaft so as to rotate integrally with a crankshaft rotatably supported by the crankcase;
It is configured so that the rotational driving force can be transmitted by engaging with the driving force output unit, and the transmitted rotational driving force can be transmitted to the valve operating mechanism provided in the cylinder head. The relay section,
An engagement state adjustment unit configured to adjust an engagement state between the driving force output unit and the relay unit;
A variable compression ratio internal combustion engine characterized by further comprising: The variable compression ratio internal combustion engine according to claim 5,
The driving force output unit and the relay unit include a disk-shaped gear,
The gear of the driving force output unit and the gear of the relay unit are arranged to mesh with each other,
The engagement state adjustment unit is
A support plate that is swingably supported by the cylinder block and is configured to rotatably support the gear of the relay portion;
An urging spring that urges the support plate so that the gear of the relay unit contacts the gear of the driving force output unit;
The variable compression ratio internal combustion engine is configured to adjust a contact state between the gear of the driving force output unit and the gear of the relay unit. The variable compression ratio internal combustion engine according to claim 6,
The engagement state adjustment unit is
A first guide portion provided on the crankcase side and configured to have a cylindrical surface;
The relay portion is provided on the support plate side so as to contact the surface of the first guide portion, and the relay portion moves on a substantially arc-shaped track following the shape of the surface. A second guide unit configured to adjust a contact state between the driving force output unit and the relay unit while guiding relative movement with respect to the driving force output unit;
A variable compression ratio internal combustion engine characterized by further comprising:

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