JP4993101B2 - Variable compression ratio internal combustion engine - Google Patents

Description

  The present invention relates to a variable compression ratio internal combustion engine configured to be able to change a compression ratio by relatively moving a cylinder block and a crankcase.

  As this type of internal combustion engine, for example, Japanese Patent Application Laid-Open Nos. 2003-206871, 2005-98176, 2005-226572, 2006-37844, 2006-316770, etc. Is disclosed.

  In such an internal combustion engine, the crankcase (also referred to as a lower case) and the cylinder block are coupled so as to be relatively movable. The connecting portion is provided with a variable compression ratio mechanism for changing the compression ratio. The variable compression ratio mechanism includes a slide mechanism for sliding the cylinder block with respect to the crankcase.

In the internal combustion engine having such a configuration, the slide mechanism is driven according to the operating state. Then, the cylinder block slides relative to the crankcase along the center axis of the cylinder. Thereby, the compression ratio is changed. For example, the compression ratio is set low to suppress knocking or the like, or the compression ratio is set high to improve fuel consumption.
JP 2003-206871 A JP 2005-98176 A JP 2005-226572 A JP 2006-37844 A JP 2006-316770 A

  During operation of the internal combustion engine, a temperature difference may occur between the cylinder block and the crankcase. The cylinder block and the crankcase have different cooling systems (the cylinder block is water-cooled while the crankcase is not water-cooled). Therefore, the above-mentioned temperature difference tends to be large. Furthermore, this temperature difference can also vary depending on the operating conditions.

  When such a temperature difference or its variation occurs, in this type of internal combustion engine, the relative movement between the cylinder block and the crankcase may not be performed smoothly. In such a case, it is difficult to appropriately control the compression ratio according to the operating state.

  The present invention has been made to address such problems. That is, an object of the present invention is to provide a variable compression ratio internal combustion engine capable of appropriately controlling a compression ratio according to an operating state by smoothly performing relative movement between the cylinder block and the crankcase. It is in.

  A variable compression ratio internal combustion engine of the present invention (hereinafter simply referred to as “the internal combustion engine of the present invention” or “internal combustion engine”) includes a cylinder block, a cylinder head, a crankcase, and a moving mechanism. . The internal combustion engine is configured such that the compression ratio can be changed by relatively moving the cylinder block, the cylinder head, and the crankcase by the moving mechanism.

  The cylinder block is formed with a cylinder that accommodates the piston in a reciprocating manner. The cylinder head is joined to the cylinder block at the end of the cylinder block on the top dead center side of the piston. The crankcase is configured to rotatably support a crankshaft that is rotationally driven based on the reciprocating movement of the piston. The moving mechanism is configured to relatively move the cylinder block and the crankcase along a central axis of the cylinder (hereinafter referred to as “cylinder central axis”).

  A feature of the present invention resides in that the internal combustion engine further includes an adjustment mechanism. The adjustment mechanism is configured to be able to adjust the temperature difference between the cylinder block and the crankcase.

  The compression ratio changing operation with such a configuration is as follows. By the moving mechanism, the cylinder block moves relative to the crankcase along the cylinder center axis. Thereby, the compression ratio is changed.

  Here, in the variable compression ratio internal combustion engine of the present invention having such a configuration, as described above, the temperature difference between the cylinder block and the crankcase is adjusted by the adjusting mechanism. Specifically, the adjustment mechanism functions so that this temperature difference is reduced.

  According to such a configuration, a temperature difference between the cylinder block and the crankcase and fluctuations thereof can be suppressed as much as possible. Thereby, the relative movement of the cylinder block and the crankcase is performed as smoothly as possible. Therefore, according to the present invention, appropriate control of the compression ratio according to the operating state can be performed.

  The internal combustion engine may be configured as follows: the adjustment mechanism includes an oil ring passage. The oil circulation passage is provided so that lubricating oil can be circulated from the cylinder head to the crankcase side. The adjustment mechanism is configured to be able to adjust a temperature difference between the cylinder block and the crankcase via the oil passing through the oil ring passage.

  In this configuration, the oil that has been lubricated by the cylinder head circulates from the cylinder head to the crankcase. At this time, the oil passes through the oil ring passage. The temperature of the oil is a temperature corresponding to the temperature of the cylinder head. Further, since the oil circulates to the crankcase through the oil ring passage, the temperature of the oil can be a temperature corresponding to the temperature of the crankcase.

  Therefore, according to such a configuration, the temperature difference between the cylinder block and the crankcase can be adjusted via the oil passing through the oil ring passage. Specifically, the temperature difference and its variation can be suppressed by the oil. Thereby, the relative movement between the cylinder block and the crankcase can be performed more smoothly. Therefore, the compression ratio can be controlled more appropriately in accordance with the operating state.

  The internal combustion engine may be configured as follows: The cylinder block is provided with a water jacket. This water jacket is a space through which the cooling medium can pass. The oil ring passage is provided in the cylinder block so as to be close to the water jacket.

  In such a configuration, heat exchange may occur between the cooling medium passing through the water jacket and the oil passing through the oil ring passage. Here, the temperature of the oil may correspond to the temperature of the crankcase as described above. On the other hand, the temperature of the cooling medium may correspond to the temperature of the cylinder block.

  Therefore, according to this configuration, the temperature difference between the cylinder block and the crankcase is adjusted by heat exchange between the cooling medium and the oil. Specifically, the temperature difference and its variation are suppressed. Accordingly, the relative movement between the cylinder block and the crankcase can be performed more smoothly. Therefore, the compression ratio can be controlled more appropriately in accordance with the operating state.

  The internal combustion engine may be configured as follows: the crankcase is provided with a cylindrical frame. A cylinder block housing portion is formed inside the frame. The cylinder block accommodating portion is a space provided along the cylinder central axis direction so as to accommodate the cylinder block. The cylinder block housing portion may be provided so as to cover from the lower end portion to the upper portion of the cylinder block. The moving mechanism is configured to move the cylinder block along the cylinder central axis in the frame.

  In this case, a predetermined clearance is provided between the inner wall surface of the frame and the outer wall surface of the cylinder block. This clearance is provided, for example, to such an extent that the relative movement between the crankcase and the cylinder block is performed smoothly, and there is no backlash between the two (specifically, whether to touch or not touch). obtain.

  In this configuration, the cylinder block is moved along the cylinder central axis direction within the frame by the moving mechanism.

  At this time, at the clearance portion, the inner wall surface of the frame and the outer wall surface of the cylinder block approach or contact each other to such an extent that they can slide. Therefore, the temperature can be satisfactorily uniformed by heat exchange between the inner wall surface and the outer wall surface in the clearance portion.

  The oil may be supplied to the clearance for lubrication. That is, the sliding part between the inner wall surface and the outer wall surface can be lubricated by the oil. At this time, heat exchange between the inner wall surface and the outer wall surface can be performed via the oil.

  According to such a configuration, the variation in the clearance due to the temperature difference between the cylinder block and the crankcase and the variation thereof can be suppressed as much as possible. Thereby, the fluctuation | variation of the friction state between both at the time of the relative movement of the said cylinder block and the said crankcase can be suppressed as much as possible. Therefore, the relative movement between the cylinder block and the crankcase can be performed more smoothly. Further, noise caused by the structure of the variable compression ratio mechanism, such as a striking sound due to the contact or collision of both, is suppressed as much as possible.

  The internal combustion engine may be configured as follows: the adjusting mechanism includes a heat transfer layer. This heat transfer layer is formed of a material having high thermal conductivity (metal or the like). The heat transfer layer is provided in a portion where the inner wall surface of the frame and the outer wall surface of the cylinder block slide by relative movement between the cylinder block and the crankcase.

  In such a configuration, heat exchange between the cylinder block and the crankcase is favorably performed through the heat transfer layer. Therefore, the temperature difference between the cylinder block and the crankcase can be adjusted effectively with a simpler device configuration.

  The heat transfer layer may be formed of a solid lubricating film that reduces friction between the inner wall surface of the frame and the outer wall surface of the cylinder block.

  In such a configuration, the temperature difference between the cylinder block and the crankcase is adjusted favorably, and the frictional resistance between the cylinder block and the crankcase is favorably reduced. Therefore, according to this configuration, the relative movement between the cylinder block and the crankcase can be performed more smoothly. Therefore, the compression ratio can be controlled more appropriately according to the operating state.

  The adjusting mechanism may include a cooling medium passage provided in the crankcase.

  In this configuration, the cylinder block is cooled by the cooling medium, and the crankcase is also cooled by the cooling medium. Thereby, adjustment of the temperature difference between the cylinder block and the crankcase can be satisfactorily performed with a simple device configuration.

  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. The various modifications that can be made to this embodiment are described together at the end because they would interfere with the understanding of a consistent embodiment description if inserted during the description of the embodiment. Yes.

<Schematic Configuration of Internal Combustion Engine of Embodiment>
1 and 2 are side sectional views showing a schematic configuration of an engine 1 which is an embodiment of an internal combustion engine of the present invention. FIG. 3 is an exploded perspective view of the engine 1 shown in FIGS. 1 and 2. Here, FIG. 1 corresponds to a cross-sectional view taken along the line II in FIG. 2 corresponds to a cross-sectional view taken along the line II-II in FIG. Hereinafter, the schematic configuration of the engine 1 will be described with reference to FIGS. 1 to 3.

  Referring to FIG. 1, the engine 1 includes a cylinder block 2, a cylinder head 3, a crankcase 4, and a variable compression ratio mechanism 5. The engine 1 is configured such that the compression ratio can be changed by moving (sliding) the cylinder block 2 and the cylinder head 3 relative to the crankcase 4.

<< Cylinder block >>
The cylinder block 2 is made of an aluminum alloy and has a substantially rectangular parallelepiped shape. A cylinder 21 is formed inside the cylinder block 2. The cylinder 21 is a substantially cylindrical through hole. A piston 22 is accommodated in the cylinder 21 so as to be capable of reciprocating along the cylinder center axis CCA.

  Referring to FIG. 3, a plurality (four in this 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.

  Referring to FIG. 1, a water jacket 23 is provided inside the cylinder block 2. The water jacket 23 is a space through which a cooling medium (cooling water) for cooling the engine 1 can pass. The water jacket 23 is provided so as to surround the outside of the cylinder 21.

  An oil ring passage 24 is formed inside the cylinder block 2. The oil circulation passage 24 is provided from the cylinder head 3 to the crankcase 4 side so that lubricating oil can be circulated. The oil ring passage 24 is provided so as to be close to the water jacket 23.

  That is, the cylinder block 2 is configured such that heat exchange can be performed between the cooling water in the water jacket 23 and the oil in the oil ring passage 24. In the present embodiment, the oil ring passage 24 is provided from the upper end surface of the cylinder block 2 (the end surface on the top dead center side of the piston 22) to the lower end surface.

  Further, as shown in FIG. 3, the oil ring passage 24 is provided at a position different from the bolt hole 25 (a position not overlapping the bolt hole 25) in the cylinder arrangement direction AD. The bolt hole 25 is a screw hole provided corresponding to a bolt (not shown) for fixing the cylinder head 3 to the cylinder block 2.

  With respect to the cylinders 21 in one row, the number of bolt holes 25 that is two more than twice the number of cylinders (10 in the example of FIG. 3) is 2 outside the water jacket 23 along the cylinder arrangement direction AD. Arranged in columns. Further, the bolt holes 25 are arranged so that the four bolt holes 25 are arranged in a substantially square shape and surround one cylinder 21 in a plan view. An oil ring passage 24 is provided between adjacent bolt holes 25 along the cylinder arrangement direction AD.

  Further, in the present embodiment, an oil supply hole 26 is formed in the cylinder block 2. The oil supply hole 26 is provided so as to communicate with the oil ring passage 24. The oil supply hole 26 is provided so as to open at the upper end of the sliding surface 27 (the side of the cylinder block 2 that slides with the crankcase 4). That is, the oil supply hole 26 is formed so that the oil can be supplied to the sliding portion between the cylinder block 2 and the crankcase 4.

<< Cylinder head >>
Referring to FIG. 1, 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 one end (the upper end in the drawing) of the cylinder 21 on the top dead center side. That is, the cylinder head 3 is fixed to the upper end portion of the cylinder block 2 by the bolt (not shown) 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 31 are formed in the cylinder head 3. Each recess 31 is provided at a position corresponding to each cylinder 21. The recess 31 is provided so as to communicate with the cylinder 21. That is, the recess 31 is provided so as to form the combustion chamber CC together with the space inside the cylinder 21 above the top surface of the piston 22 when the cylinder head 3 is fixed to the cylinder block 2.

  An intake port 32 and an exhaust port 33 are formed in the cylinder head 3 so as to communicate with the combustion chamber CC. The cylinder head 3 is provided with an intake valve 34 and an exhaust valve 35. The intake valve 34 is configured to open and close the intake port 32. The exhaust valve 35 is configured to open and close the exhaust port 33.

  Further, an oil ring passage 36 is formed in the cylinder head 3. The oil ring passage 36 is provided so as to communicate with the oil ring passage 24 provided in the cylinder block 2. The oil ring passage 36 is formed so that the oil supplied to the cylinder head 3 for lubricating the intake valve 34 and the exhaust valve 35 can be introduced into the oil ring passage 24 of the cylinder block 2.

<< Crankcase >>
Referring to FIGS. 1 to 3, the crankcase 4 includes a cylindrical frame 41. The crankcase 4 is integrally formed of an aluminum alloy.

  The frame 41 is formed to have a longitudinal direction parallel to the cylinder arrangement direction AD. The frame 41 is formed in a shape surrounding the sliding surface 27 of the cylinder block 2. The clearance between the frame 41 and the sliding surface 27 is set to such an extent that the cylinder block 2 and the crankcase 4 can slide smoothly without rattling (degrees of touching or not touching: for example, about several millimeters). ing.

  That is, a cylinder block housing portion 41 a is formed inside the frame 41. The cylinder block accommodating portion 41a is a space in which the cylinder block 2 can be accommodated, and is provided along the cylinder center axis CCA. The cylinder block accommodating portion 41a is provided so as to open upward in the drawing so that the cylinder block 2 can be inserted from above in the drawing.

  The inner wall surface of the cylinder block housing portion 41a (frame 41) is provided with the above-mentioned predetermined clearance with the sliding surface 27 that is the outer wall surface on the side of the cylinder block 2 in a state in which the cylinder block 2 is housed. It is formed as follows. Further, the frame 41 (cylinder block accommodating portion 41a) is formed so as to smoothly guide the relative movement between the cylinder block 2 and the cylinder head 3 by covering from the lower end portion to the upper portion of the cylinder block 2. . Note that the upper end portion of the cylinder block 2 is provided so as to protrude above the frame 41 for joining with the cylinder head 3.

  A crankshaft 42 is rotatably supported on the lower end of the crankcase 4 via a bearing. The crankshaft 42 is disposed in parallel with the cylinder arrangement direction AD. The crankshaft 42 is driven to rotate based on the reciprocating movement of the piston (see FIG. 1) along the cylinder center axis CCA.

  An oil ring passage 43 is provided in the crankcase 4. The oil ring channel 43 communicates with the opening on the lower end side of the oil ring channel 24 in the cylinder block 2 and can receive the oil flowing down from the clearance between the sliding surface 27 and the frame 41. It is formed in a shape that spreads upward. The oil ring channel 43 is provided so that the oil received from the clearance and oil ring channel 24 can be circulated toward the crankcase 4 and an oil pan (not shown) connected to the lower end thereof. .

<< Heat exchange mechanism between cylinder block and crankcase >>
As described above, in the engine 1 of the present embodiment, the sliding surface 27 of the cylinder block 2 is surrounded by the inner wall surface of the frame 41 in the crankcase 4. The inner wall surface and the sliding surface 27 of the cylinder block 2 slide when the cylinder block 2 and the crankcase 4 move relative to each other.

  Further, the engine 1 of the present embodiment is configured such that the oil is supplied to the sliding portion between the sliding surface 27 of the cylinder block 2 and the inner wall surface of the frame 41 in the crankcase 4.

  And the engine 1 of this embodiment is comprised so that the heat exchange between the cylinder block 2 and the crankcase 4 may be performed in this sliding part. Specifically, the oil between the sliding surface 27 of the cylinder block 2 and the inner wall surface of the frame 41 in the crankcase 4 and the oil existing in the clearance between the two is provided between the cylinder block 2 and the crankcase 4. Heat exchange is performed.

  Further, as described above, the engine 1 of the present embodiment is configured such that heat exchange is performed between the cooling water in the water jacket 23 and the oil in the oil ring passage 24.

<Specific Configuration of Variable Compression Ratio Mechanism of Embodiment>
Referring to FIGS. 1 to 3, a pair of variable compression ratio mechanisms 5 are provided on both side walls and in the vicinity thereof along the cylinder arrangement direction AD of the frame 41. One variable compression ratio mechanism 5 and the other variable compression ratio mechanism 5 are arranged and configured substantially symmetrically with respect to a plane through which the cylinder center axis CCA of all the cylinders 21 passes.

<< Camshaft >>
The variable compression ratio mechanism 5 is configured to be able to relatively move (slide) the cylinder block 2 and the crankcase 4 along the cylinder center axis CCA by the rotational drive of the camshaft 51. The cam shaft 51 is made of carbon steel for mechanical structure (S45C or the like), and includes a journal portion 51a, a circular cam portion 51b, an eccentric shaft portion 51c, and a worm wheel 51d.

  FIG. 4 is a perspective view showing a part of the camshaft 51 shown in FIGS. 1 to 3 in an exploded manner. Hereinafter, referring to FIGS. 1 to 4, the journal portion 51a is a cylindrical member, and is a rotation center axis of the camshaft 51 (this is parallel to the cylinder arrangement direction AD, that is, perpendicular to the cylinder center axis CCA). In FIG. 4, it is indicated by a one-dot chain line).

  The surface 51a1 of the journal part 51a is formed in a cylindrical surface shape. The surface 51a1 is provided with a coating for reducing friction and wear. Specifically, the surface 51a1 is coated with DLC (diamond-like carbon). The journal portion 51 a is provided between the adjacent circular cam portions 51 b and at both ends of the camshaft 51.

  The circular cam portion 51b is provided eccentric from the rotation center axis. The circular cam portion 51b is a cylindrical member having a diameter larger than that of the journal portion 51a, and is provided according to the number of cylinders. That is, the same number (4 in the present embodiment) of circular cam portions 51b as the number of cylinders is provided for one camshaft 51. Each circular cam portion 51b is disposed at a position corresponding to the cylinder center axis CCA.

  A surface 51b1 of the circular cam portion 51b is formed in a cylindrical surface shape. Similarly to the surface 51a1 of the journal portion 51a, the surface 51b1 is also coated to reduce friction and wear.

  The eccentric shaft portion 51c is a round bar member having a longitudinal direction along the cylinder arrangement direction AD. A worm wheel 51d is provided at substantially the center in the longitudinal direction of the eccentric shaft portion 51c. The worm wheel 51d is formed integrally with the eccentric shaft portion 51c. The worm wheel 51d is provided such that its central axis is coaxial with the rotation central axis. The worm wheel 51d is rotationally driven by meshing with a worm W that is a cylindrical gear mounted on a rotational drive shaft of the motor M (which is perpendicular to the rotational central axis and the cylinder central axis CCA). It is like that.

  The eccentric shaft portion 51c is provided so as to be inserted at a position eccentric from the central axis of the journal portion 51a and the central axis of the circular cam portion 51b. That is, as shown in FIG. 1 and FIG. 4, in a state where one end (the lower end in the figure) of the journal portion 51 a and one end (the lower end in the figure) of the circular cam portion 51 b coincide, An eccentric shaft portion 51c is provided so as to pass through the journal portion 51a and the circular cam portion 51b at the lower portion.

  The journal portion 51a is fixed to the eccentric shaft portion 51c so as not to rotate around the eccentric shaft portion 51c. That is, the journal portion 51a can be driven to rotate integrally with the worm wheel 51d around the rotation center axis as the worm wheel 51d rotates. On the other hand, the circular cam portion 51b can freely rotate around the eccentric shaft portion 51c. That is, the circular cam portion 51b can be rotated relative to the journal portion 51a.

<< Block side support part >>
1 to 3, the circular cam portion 51 b is rotatably supported by the block side support portion 52. The block-side support portion 52 is a block-shaped member and is integrally (seamlessly) formed of bearing steel. A bearing hole 52 a is formed in the block side support portion 52. The bearing hole 52a 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 51b1 of the circular cam portion 51b).

  FIG. 5 is a perspective view showing the cylinder block 2 shown in FIG. FIG. 6 is an exploded perspective view of the cylinder block 2 and the block-side support portion 52 shown in FIG. Referring to FIGS. 3 to 6 and FIG. 1, the block side support portion 52 is formed separately from the cylinder block 2 and is configured to be attached to the cylinder block 2 using a bolt. . The block support 52 is provided at a position corresponding to the cylinder center axis CCA.

  With reference to FIGS. 1 to 3, the frame 41 is provided with the same number of openings 53 as the block side support portions 52. The opening 53 is a through-hole, and is provided so that the block-side support 52 can penetrate. The opening 53 is larger than the height dimension of the block-side support 52 (the dimension in the direction along the cylinder center axis CCA) so that the block-side support 52 can reciprocate along the cylinder center axis CCA. It is formed to a height dimension.

<< Crankcase side support part >>
A plurality of frame side support portions 54 are formed on the frame 41. As shown in FIG. 3, each frame-side support portion 54 is provided so as to be adjacent to the opening 53. In other words, the plurality of frame side support portions 54 are provided on both sides of each opening 53 and are arranged along the cylinder arrangement direction AD.

  The frame side support portion 54 is provided with a journal support recess 54a. The journal support recess 54a is a semi-cylindrical recess and is formed to have an inner diameter corresponding to the outer diameter of the journal portion 51a.

  7A and 7B are enlarged side sectional views of the periphery of the frame side support portion 54 shown in FIG. Referring to FIGS. 7A and 7B, a liner 54b is provided in a portion of the journal support recess 54a that faces the journal portion 51a. The liner 54b is made of a bearing steel having a higher wear resistance than the other part (aluminum alloy) of the frame side support part 54, and is formed in a semi-cylindrical shape.

  Referring to FIGS. 1 to 3, a cover portion 55 is attached to the frame 41. The cover portion 55 is made of an aluminum alloy, and is provided so as to face the frame-side support portion 54 with the camshaft 51 (journal portion 51a) interposed therebetween. The cover portion 55 is configured to be rotatably attached to the camshaft 51 (journal portion 51a) together with the frame side support portion 54 by being attached to the frame side support portion 54.

  The cover portion 55 is formed integrally (seamlessly) so as to correspond to the plurality of frame side support portions 54 (all the frame side support portions 54 in one variable compression ratio mechanism 5). The cover portion 55 is formed with a journal support recess 55a, a bearing housing portion 55b, and a gear housing portion 55c.

  The journal support recess 55a is a semi-cylindrical recess symmetrical to the journal support recess 54a of the frame side support 54, and has an inner diameter corresponding to the outer diameter of the journal portion 51a. That is, the cover part 55 is configured in a substantially arch shape along the cylinder center axis CCA in a side sectional view. The journal support recess 55a is provided to face the journal support recess 54a.

  The bearing housing portion 55 b is a concave portion provided at a position facing the block side support portion 52. The bearing accommodating portion 55b is formed so as to accommodate the block-side support portion 52 protruding from the opening 53 to the outside of the frame 41 so as to be reciprocally movable along the cylinder center axis CCA. Moreover, the gear accommodating part 55c is a recessed part provided in the position facing the worm wheel 51d. The gear accommodating portion 55c is formed so as to accommodate the worm wheel 51d protruding to the outside of the frame 41.

  Referring to FIGS. 7A and 7B, a liner 55d is provided in a portion of the journal support recess 55a that faces the journal portion 51a. The liner 55d is made of a bearing steel having a higher wear resistance than the other part (aluminum alloy) of the cover part 55, and is formed in a semi-cylindrical shape. The cover portion 55 is fixed to the frame side support portion 54 by the bolt 56, and the liner 55d is joined to the liner 54b, thereby forming a bearing hole that rotatably supports the journal portion 51a inside these joined bodies. It has come to be.

<Description of Operation of Variable Compression Ratio Mechanism of Embodiment>
FIGS. 8 to 10 are views showing the compression ratio changing operation in the engine 1 shown in FIG. Hereinafter, the compression ratio changing operation by the variable compression ratio mechanism 5 will be described with reference to these drawings.

  In the state where the compression ratio of the engine 1 is the highest, as shown in FIG. 8, the eccentric shaft portion 51c is located at the lowest position. In this case, the circular cam portion 51b is also located at the lowest position.

  When the process of lowering the compression ratio from the maximum value is performed, the camshaft 51 is rotationally driven from the state shown in FIG. 8 as indicated by the arrow in the figure (the camshaft 51 on the right side in the figure). Is rotated clockwise and the camshaft 51 on the left side in the drawing is rotated counterclockwise).

  At this time, the journal portion 51a slides on the inner surfaces of the liners 54b and 55d, and the bearing formed between the frame side support portion 54 and the cover portion 55 around the rotation center axis of the camshaft 51. Rotates inside the hole. The eccentric shaft portion 51c rotates around the rotation center axis together with the journal portion 51a.

  On the other hand, the circular cam portion 51b rotates inside the block-side support portion 52 around an axis different from the rotation center axis while sliding with the inner surface of the bearing hole 52a. Moreover, the circular cam part 51b rotates relatively with respect to the eccentric shaft part 51c.

  Then, the eccentric shaft portion 51c rises from the position shown in FIG. 8, and the circular cam portion 51b rises. Therefore, as shown in FIG. 9, the block-side support portion 52 rises as the circular cam portion 51 b rises due to the rotation of the camshaft 51.

  Therefore, the cylinder block 2 rises relative to the crankcase 4. As the cylinder block 2 is raised, the cylinder head 3 is separated from the crankcase 4, whereby the distance between the top dead center position of the piston 22 and the lower end surface of the cylinder head 3 is extended. That is, the compression ratio of the engine 1 is reduced.

  As shown in FIG. 9, when the position of the eccentric shaft portion 51c is intermediate between the uppermost and lowermost positions, the compression ratio is also intermediate between the highest value and the lowest value. As shown in FIG. 10, when the position of the eccentric shaft portion 51c reaches the uppermost position, the compression ratio becomes the lowest.

  When the compression ratio is increased from the state shown in FIG. 10 where the compression ratio of the engine 1 is the lowest, the camshaft 51 is further driven to rotate in the same direction as described above, or the camshaft 51 is reversed from the above. It is rotationally driven in the direction.

  Thus, when the cylinder block 2 and the crankcase 4 are relatively moved to change the compression ratio, the sliding surface 27 that is the outer wall surface on the side of the cylinder block 2 and the inner wall surface of the frame 41 slide. Move. The oil is appropriately supplied from the oil ring passage 24 to the sliding portion.

  The oil used for lubrication in the cylinder head 3 has a temperature corresponding to the temperature of the cylinder head 3 by absorbing heat in the cylinder head 3. This oil is supplied to the sliding portion. In addition, this oil circulates to the crankcase 4 via the oil circulation passage 24. Therefore, the temperature of the oil supplied to the sliding portion can be a temperature corresponding to the temperature of the crankcase 4.

<Effects of Configuration of Embodiment>
Hereinafter, effects of the configuration of the present embodiment will be described with reference to the drawings.

  Referring to FIGS. 1 and 2, in the engine 1 of the present embodiment, at the sliding portion between the sliding surface 27 of the cylinder block 2 and the inner wall surface of the frame 41 in the crankcase 4, the cylinder block 2 And heat exchange between the crankcase 4 and the crankcase 4. This heat exchange is performed through the contact between the two at the sliding portion and / or the oil supplied to the sliding portion.

  According to such a configuration, the temperature difference between the cylinder block 2 and the crankcase 4 is adjusted favorably. That is, the temperature difference between the cylinder block 2 and the crankcase 4 and its fluctuation can be suppressed as much as possible. Therefore, the fluctuation | variation of the clearance between the flame | frame 41 and the sliding surface 27 and the fluctuation | variation of the friction state by this can be suppressed as much as possible.

  Thereby, the relative movement of the cylinder block 2 and the crankcase 4 is performed as smoothly as possible. Therefore, appropriate control of the compression ratio according to the operating state can be performed.

  In addition, the reliability of the oil seal for preventing the oil leakage in the above-described clearance can be maintained well. Furthermore, noise caused by the structure of the variable compression ratio mechanism, such as a striking sound caused by contact or collision between the cylinder block 2 and the frame 41, is suppressed as much as possible.

  Referring to FIG. 1, in the engine 1 of the present embodiment, heat exchange is also performed between the cooling water in the water jacket 23 and the oil in the oil ring passage 24. Here, the temperature of the oil may correspond to the temperature of the crankcase 4 as described above. On the other hand, the temperature of the cooling water may correspond to the temperature of the cylinder block 2.

  According to such a configuration, the temperature difference between the cylinder block 2 and the crankcase 4 is more favorably adjusted by heat exchange between the cooling water and the oil.

  In addition, during high-load operation, the oil that reaches a high temperature is well cooled by the cooling water. Thereby, cooling of the engine 1 can be performed favorably. Further, during the warm-up operation, heat is given to the oil from the cooling water that is relatively easily heated by heat from fuel combustion or the like. Thereby, warm-up of the engine 1 can be accelerated | stimulated favorably.

  In the present embodiment, the block-side support portion 52 that supports the camshaft 51 by accommodating the journal portion 51 a on the cylinder block 2 side is formed separately from the cylinder block 2. The cylindrical frame 41 is provided with an opening 53 so as to correspond to the block side support portion 52. Further, a crankcase side support portion that supports the camshaft 51 on the crankcase 4 side is constituted by a frame side support portion 54 and a cover portion 55. The camshaft 51 is supported by the crankcase 4 by attaching the cover portion 55 to the frame side support portion 54.

  According to such a configuration, the assembly of the camshaft 51 and the block-side support portion 52 is attached to the cylinder block 2 and the crankcase 4 in a very simple process. Therefore, according to the present embodiment, the ease of assembling work between the cylinder block 2 and the crankcase 4 is improved. Further, the rigidity of the crankcase 4 is improved.

  Furthermore, according to this structure, the cylinder block 2 and the block side support part 52 can be comprised with a different material. Thus, the weight of the engine 1 can be reduced well, and the rigidity of the block-side support portion 52 can be improved and the wear can be suppressed well.

  In the present embodiment, the surface of the camshaft 51 is coated for reducing wear and friction. Therefore, the rotational drive of the camshaft 51 can be performed smoothly. Moreover, the wear accompanying the rotational drive of the camshaft 51 can be effectively suppressed. As a result, the compression ratio changing operation can be performed more smoothly and reliably (especially when starting or when the engine is stopped, which tends to be insufficient in the amount of lubricating oil).

<List of examples of modification>
Note that, as described above, the above-described embodiment is merely an example of a specific configuration of the present invention considered to be the best by the applicant at the time of filing of the present application. It should not be limited at all by the embodiment. Therefore, it goes without saying that various modifications can be made to the specific configurations shown in the above-described embodiments within a range that does not change the essential part of the present invention.

  Hereinafter, some modifications will be exemplified. Here, in the following description of the modified example, components having the same configurations and functions as the components in the above-described embodiment are given the same name and the same reference numerals in the modified example. And And about description of the said component, description in the above-mentioned embodiment shall be used suitably in the range which is not inconsistent.

  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 beneficial and not allowed.

  Further, it goes without saying that the configuration of the above-described embodiment and the configuration described in each of the following modifications can be applied in an appropriate combination within a technically consistent range.

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

  (2) The oil ring passage 24 may be provided on both sides of the cylinder 21 in the engine width direction (direction orthogonal to the longitudinal direction: the left-right direction in FIG. 1).

  (3) FIG. 11 is a side sectional view showing a configuration of a modification of the engine 1 of the embodiment shown in FIG. Referring to FIG. 11, the oil supply hole 26 may be omitted.

  That is, heat exchange by contact between the sliding surface 27 of the cylinder block 2 and the inner wall surface of the frame 41 in the crankcase 4 and / or the cooling water in the water jacket 23 and the oil in the oil ring passage 24. According to the heat exchange in between, temperature adjustment for smooth relative movement between the cylinder block 2 and the crankcase 4 can be performed satisfactorily.

  (4) FIG. 12 is a side sectional view showing the configuration of another modification of the engine 1 shown in FIG. Referring to FIG. 12, a water jacket 44 may be provided in the vicinity of the above-described sliding portion of the frame 41 (crankcase 4). The water jacket 44 is configured to allow the cooling water to flow.

  In such a configuration, unlike the above-described embodiment, not only the cylinder block 2 is cooled by the cooling water, but also the crankcase 4 (frame 41) is cooled. Thereby, adjustment of the temperature difference between the cylinder block 2 and the crankcase 4 can be performed more effectively with a simple device configuration.

  (5) The positional relationship between the oil ring passage 24 and the bolt hole 25 is not particularly limited.

  FIG. 13 is an exploded perspective view showing the configuration of another modification of engine 1 shown in FIG. Referring to FIG. 13, the oil ring passage 24 may be provided at a position overlapping the bolt hole 25 in the cylinder arrangement direction AD.

  In this case, as shown in FIG. 13, the oil ring passage 24 may be provided outside the bolt hole 25. Alternatively, contrary to the case of FIG. 13, the oil ring flow path 24 may be provided at a position closer to the water jacket 23 than the bolt hole 25.

  (6) FIG. 14 is a perspective view showing a configuration of a modification of the cylinder block 2 shown in FIG. Referring to FIG. 14, a coating layer 271 as a solid lubricating film may be provided on the peripheral surface of the cylinder block 2. In this case, the sliding surface 27 is constituted by the surface of the coating layer 271.

  Here, the coating layer 271 is configured to have a high thermal conductivity and a low friction surface. Specifically, the coating layer 271 includes DLC (diamond-like carbon), a ceramic coating (for example, chromium oxide, silicon nitride, silicon carbide, or alumina as a main component, such as carbon short fibers). Solid lubricants can be blended as appropriate.) Solid lubricant films such as molybdenum disulfide and hard chromium carbide plating can be used favorably.

  According to this configuration, the temperature difference between the cylinder block 2 and the crankcase 4 is adjusted well, and the cylinder block 2 (sliding surface 27) and the crankcase 4 (inner wall surface of the frame 41) slide. In this case, the frictional resistance is favorably reduced. Therefore, the relative movement between the cylinder block 2 and the crankcase 4 is performed more smoothly. Therefore, the compression ratio can be controlled more appropriately according to the operating state.

  The coating layer 271 may be provided on the inner wall surface side of the frame 41 together with or in place of the sliding surface 27.

  (7) FIG. 15 is a perspective view showing the configuration of another modification of the cylinder block 2 shown in FIG. Referring to FIG. 15, a heat conduction seal 272 may be attached to the cylinder block 2. The heat conductive seal 272 is a metal ring-shaped member made of the same material as the piston ring or the like. The heat conduction seal 272 is configured to perform functions of heat conduction and an oil seal at a sliding portion between the sliding surface 27 of the cylinder block 2 and the inner wall surface of the frame 41 in the crankcase 4.

  According to such a configuration, the adjustment of the temperature difference between the cylinder block 2 and the crankcase 4 and the sealing of the oil in the clearance between the inner wall surface of the frame 41 and the sliding surface 27 can be performed well with a simple device configuration. Can be broken.

  The heat conductive seal 272 can also be formed of a non-metallic material (for example, ceramics) having a thermal conductivity equivalent to that of a metal, or a material (for example, cermet) having the main component thereof (for example, cermet).

  (8) Other modifications that are not specifically mentioned are naturally included in the technical scope of the present invention without departing from the essential part of the present invention. For example, 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.

  In addition, 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.

It is a sectional side view (II sectional drawing in FIG. 3) which shows schematic structure of the engine which is one Embodiment of this invention. It is a sectional side view (II-II sectional view in Drawing 3) showing a schematic structure of an engine which is one embodiment of the present invention. FIG. 3 is an exploded perspective view of the engine shown in FIGS. 1 and 2. FIG. 4 is a perspective view showing a part of the camshaft shown in FIGS. 1 to 3 in an exploded manner. It is a perspective view which takes out and shows the cylinder block shown by FIG. It is a disassembled perspective view of the cylinder block and block side support part which are shown by FIG. FIG. 3 is an enlarged side sectional view of a periphery of a frame side support portion shown in FIG. 2. FIG. 3 is an enlarged side sectional view of a periphery of a frame side support portion shown in FIG. 2. It is a figure which shows the mode of the compression ratio change operation | movement in the engine shown by FIG. It is a figure which shows the mode of the compression ratio change operation | movement in the engine shown by FIG. It is a figure which shows the mode of the compression ratio change operation | movement in the engine shown by FIG. It is a sectional side view which shows the structure of the modification of the engine of embodiment shown by FIG. It is a sectional side view which shows the structure of the other modification of the engine of embodiment shown by FIG. It is a disassembled perspective view which shows the structure of the other modification of the engine of embodiment shown by FIG. It is a perspective view which shows the structure of the modification of the cylinder block shown by FIG. It is a perspective view which shows the structure of the other modification of the cylinder block shown by FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Engine 2 ... Cylinder block 21 ... Cylinder 22 ... Piston 23 ... Water jacket 24 ... Oil ring flow path 27 ... Sliding surface 271 ... Coating layer 272 ... Heat conduction seal 3 ... Cylinder head 4 ... Crank case 41 ... Frame 41a ... Cylinder Block housing portion 42 ... Crankshaft 44 ... Water jacket 5 ... Variable compression ratio mechanism AD ... Cylinder arrangement direction CC ... Combustion chamber CCA ... Cylinder center axis M ... Motor W ... Worm

Claims (4)

A cylinder block formed with a cylinder for reciprocally moving the piston;
A cylinder head joined to the cylinder block at the top dead center side end of the piston;
A crankcase configured to rotatably support a crankshaft that is rotationally driven based on the reciprocating movement of the piston; and
A moving mechanism configured to be able to relatively move the cylinder block and the crankcase along a central axis of the cylinder;
With
In the variable compression ratio internal combustion engine configured to change the compression ratio by relatively moving the cylinder block, the cylinder head, and the crankcase by the moving mechanism,
An adjustment mechanism configured to adjust a temperature difference between the cylinder block and the crankcase;
The crankcase includes a cylindrical frame having a cylinder block housing portion formed therein, which is a space provided along the central axis direction so as to accommodate the cylinder block.
The moving mechanism is configured to be able to move the cylinder block along the central axis direction in the frame,
The adjustment mechanism is provided in a portion where the inner wall surface of the frame and the outer wall surface of the cylinder block slide by relative movement between the cylinder block and the crankcase, and is formed of a material having high thermal conductivity. With a heat transfer layer ,
The variable compression ratio internal combustion engine , wherein the heat transfer layer is formed of a solid lubricating film that reduces friction between the inner wall surface and the outer wall surface . The variable compression ratio internal combustion engine according to claim 1 ,
The adjustment mechanism is
An oil ring flow path provided so that lubricating oil can be circulated from the cylinder head to the crankcase side;
A variable compression ratio internal combustion engine configured to be able to adjust a temperature difference between the cylinder block and the crankcase through the oil passing through the oil ring passage. A variable compression ratio internal combustion engine according to claim 2 ,
The cylinder block is provided with a water jacket that is a space through which a cooling medium can pass,
The variable compression ratio internal combustion engine, wherein the oil ring passage is provided in the cylinder block so as to be close to the water jacket. A variable compression ratio internal combustion engine according to any one of claims 1 to 3 ,
The variable compression ratio internal combustion engine, wherein the adjustment mechanism includes a coolant passage provided in the crankcase.

Images