JP6375769B2 - Bearing structure for a multi-link piston crank mechanism of an internal combustion engine. - Google Patents

Description

  The present invention relates to a bearing structure for a crankshaft of a multi-link type piston crank mechanism.

  For example, in Patent Document 1, as a piston crank mechanism in an internal combustion engine, a lower link supported by a crankpin of a crankshaft, an upper link that connects one end of the lower link and a piston pin, and the other end of the lower link A multi-link type piston crank mechanism is disclosed that includes a control link that connects the shaft and the eccentric shaft portion of the control shaft.

  In such a multi-link type piston crank mechanism, it is necessary to rotatably support the crankshaft and the control shaft. Therefore, in Patent Document 1, the crankshaft is supported between the bulkhead of the cylinder block and the main bearing cap, and the control shaft bearing cap is attached to the lower side of the main bearing cap. A bearing structure that supports the control shaft between the two is disclosed.

  The control shaft bearing cap has a bearing beam structure in which a plurality of bearing caps are connected in a ladder shape with a beam portion extending in the longitudinal direction of the engine. The control shaft bearing cap is formed from an oil gallery formed in the beam portion. Lubricating oil is supplied to each part.

JP 2004-116434 A

  However, in the configuration in which lubricating oil is supplied to the control shaft bearing portion through the inside of the beam portion as in Patent Document 1, it is essential that the control shaft bearing cap has a bearing beam structure, and the degree of freedom in design is small. Moreover, since the bearing beam structure is provided with an oil gallery, there is a problem that the configuration is complicated.

A bearing structure of a multi-link type piston crank mechanism for an internal combustion engine according to the present invention includes a main bearing metal that rotatably supports a crankshaft on a crankshaft bearing portion composed of a cylinder block and a main bearing cap, and a multi-link type A control shaft bearing portion that rotatably supports the control shaft of the piston crank mechanism, and an oil groove is formed along the circumferential direction on the inner circumferential surface of the crankshaft bearing portion. The crankshaft bearing portion has a main bearing cap side bearing surface formed on the main bearing cap. The oil groove is formed so as not to exceed the center position in the circumferential direction of the main bearing cap side bearing surface. The oil groove is connected to an oil passage in the block from the oil gallery to the crankshaft bearing portion and an oil passage in the cap from the crankshaft bearing portion to the control shaft bearing portion.

  According to the present invention, since the lubricating oil is supplied from the oil gallery of the cylinder block to the control shaft bearing portion via the crankshaft bearing portion, the control shaft bearing cap does not necessarily have a beam structure, and the design freedom As the degree increases, the configuration of the oil passage becomes simple.

Explanatory drawing which showed typically schematic structure of the multilink type piston crank mechanism to which this invention is applied. 1 is a cross-sectional view schematically showing a bearing structure of a multi-link type piston crank mechanism for an internal combustion engine according to the present invention. Sectional drawing which shows the detail of the oil path of a crankshaft bearing part and a control shaft bearing part. Sectional drawing along the AA line of FIG. Sectional drawing along the BB line of FIG.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is an explanatory view schematically showing a schematic configuration of a multi-link type piston crank mechanism 1 to which the present invention is applied. The multi-link type piston crank mechanism 1 includes a lower link 3 rotatably attached to a crank pin 2, an upper link 5 connecting the lower link 3 and the piston 4, and a control provided with an eccentric shaft portion 6. The shaft 7 includes a control link 8 that connects the eccentric shaft portion 6 and the lower link 3.

  The crankshaft 9 is rotatably supported by a crankshaft bearing portion 12 including a cylinder block 10 and a main bearing cap 11.

  One end of the upper link 5 is rotatably connected to the piston 4 via the piston pin 13, and the other end is rotatably connected to one end portion of the lower link 3 via the first connection pin 14.

  One end of the control link 8 is rotatably connected to the other end portion of the lower link 3 via the second connecting pin 15, and the other end is rotatably connected to the eccentric shaft portion 6.

  The control shaft 7 is disposed below the crankshaft 9 in parallel with the crankshaft 9 and is rotatably supported by a control shaft bearing portion 17 including a main bearing cap 11 and a control shaft bearing cap 16. Yes. The control shaft 7 is rotationally driven by an actuator (not shown), and its rotational position is controlled. The actuator may be, for example, an electric motor or a hydraulically driven actuator.

  In this multi-link type piston crank mechanism 1, when the control shaft 7 is rotated by the actuator, the center position of the eccentric shaft portion 6 changes, and the swing support position of the other end of the control link 8 changes. When the swing support position of the control link 8 changes, the stroke of the piston 4 in the cylinder 18 changes, and the position of the piston 4 at the piston top dead center (TDC) increases or decreases. This makes it possible to change the engine compression ratio.

  As shown in FIG. 2, the main bearing cap 11 is attached to the lower edge of the cylinder block 10, specifically, the lower edge of the bulkhead 21 between the cylinders with three bolts 22, 23 and 24. The control shaft bearing cap 16 is attached to the lower edge of the main bearing cap 11. More specifically, two bolts 23 and 24 among the three bolts 22 to 24 pass through both the main bearing cap 11 and the control shaft bearing cap 16, and the main bearing cap is in a so-called co-tightened form. 11 and a control shaft bearing cap 16 are fixed to the cylinder block 10. As shown in FIG. 2, the two bolts 23 and 24 pass through both sides of the crankshaft bearing portion 12 and the control shaft bearing portion 17 that are circular openings, respectively. The joining surface of the main bearing cap 11 and the bulkhead 21 and the joining surface of the main bearing cap 11 and the control shaft bearing cap 16 are parallel to each other, and both are along a plane orthogonal to the central axis L of the cylinder 18. Yes.

  The bolts 22 to 24 may be ordinary bolts having a head, or may be stud bolts used in combination with nuts.

  Next, a lubricating oil supply system for the crankshaft bearing portion 12 and the control shaft bearing portion 17 will be described.

  As shown in FIG. 2, an oil gallery 25 extending linearly in the cylinder row direction is formed inside the cylinder block 10. The oil gallery 25 is located in the vicinity of the upper edge of the skirt portion on the control link 8 side, and communicates with the discharge side of an oil pump (not shown) via an oil supply passage 26.

  The oil gallery 25 is connected to an in-block oil passage 27. The block internal oil passage 27 passes through the bulk head 21 and supplies lubricating oil from the oil gallery 25 to the crankshaft bearing portion 12. The oil passage 27 in the block is a straight oil passage drilled from the lower surface side of the cylinder block 10, and the central axis of the cylinder 18 is directed to the top of the crankshaft bearing portion 12 that forms a circle from the oil gallery 25. Inclined with respect to L.

  Further, in the main bearing cap 11, an in-cap oil passage 28 for supplying a part of the lubricating oil supplied to the crankshaft bearing portion 12 to the control shaft bearing portion 17 is formed.

  The cap internal oil passage 28 is a straight oil passage drilled in the main bearing cap, and has an upper end opened near the bottom of the crankshaft bearing portion 12 and a lower end formed at the top of the circular control shaft bearing portion 17. It is open. The cap internal oil passage 28 is parallel to the central axis L of the cylinder 18.

  Here, as shown in FIG. 2, in the posture in which the center axis L of the cylinder 18 is upright, the center of the crankshaft bearing portion 12 and the center of the control shaft bearing portion 17 are slightly offset in the left-right direction. . Specifically, the center of the control shaft bearing portion 17 is slightly offset from the center of the crankshaft bearing portion 12 on the right side in FIG.

  2 and the like, the diameter of the control shaft 7 (specifically, the diameter of the journal portion) is smaller than the diameter of the crankshaft 9 (specifically, the diameter of the journal portion).

  Next, oil passages in the crankshaft bearing portion 12 and the control shaft bearing portion 17 will be described with reference to FIGS. In FIG. 3, for convenience of illustration, the crankshaft bearing portion 12 and the control shaft bearing portion 17 are drawn close to each other, and therefore the in-cap oil passage 28 is shorter than the original dimension.

  As shown in FIG. 3, the crankshaft bearing portion 12 includes a semicircular cylinder block side bearing surface 31 formed in the bulkhead 21 and a semicircular main bearing cap side bearing formed in the main bearing cap 11. And a surface 32.

  The cylinder block side bearing surface 31 continues from one end of the cylinder block side bearing surface 31 on the oil gallery 25 side (right side in FIG. 3) to a position beyond the center position in the circumferential direction, and the shaft of the crankshaft bearing portion 12 A cylinder block side oil groove 33 located in the center of the direction is formed. The cylinder block side oil groove 33 is open at the lower end of the oil passage 27 in the block.

  The main bearing cap side bearing surface 32 is continuous from one end of the main bearing cap side bearing surface 32 on the oil gallery 25 side (right side in FIG. 3) to a position beyond the center position in the circumferential direction, and the crankshaft bearing portion 12. A main bearing cap side oil groove 34 is formed at the center in the axial direction. The upper end of the oil passage 28 in the cap is opened in the main bearing cap side oil groove 34.

Incidentally, in the state assembled with the main bearing cap 11 to the bulk head 21, the cylinder block side oil groove 33 and the main bearing cap side oil groove 34 is intended to continuously. 4 and 5 is a bolt hole into which the bolt 24 is inserted.

  A main bearing metal 41 is mounted on the crankshaft bearing portion 12 constituted by the cylinder block side bearing surface 31 and the main bearing cap side bearing surface 32. That is, the crankshaft 9 is rotatably supported by the crankshaft bearing portion 12 via the main bearing metal 41.

  The main bearing metal 41 is formed with a main bearing metal flat portion 42 that rotatably supports the crankshaft on the entire inner peripheral surface and a main bearing metal side oil groove 43 along the circumferential direction over the entire length of the inner peripheral surface. Main bearing metal oil groove 44. In other words, the main bearing metal 41 includes a main bearing metal oil groove portion 44 in which the main bearing metal side oil groove 43 is formed on the inner peripheral surface, and a main bearing in which the main bearing metal side oil groove 43 is not formed on the inner peripheral surface. The metal flat part 42 is comprised. As shown in FIG. 4, the main bearing metal side oil groove 43 is positioned at the center of the main bearing metal 41 in the axial direction (vertical direction in FIG. 4).

  The main bearing metal 41 includes a pair of half-shaped main bearing metal members 45 and 46. The upper main bearing metal member 45 has a semicylindrical shape and is mounted so as not to rotate with respect to the cylinder block side bearing surface 31. The lower main bearing metal member 46 has a semicylindrical shape and is mounted so as not to rotate with respect to the main bearing cap side bearing surface 32.

  In addition, between the inner peripheral surface of the crankshaft bearing portion 12 and the outer peripheral surface of the main bearing metal 41, for example, an engaging portion having a claw shape is provided to prevent the main bearing metal 41 from rotating. The illustration is omitted.

  A main bearing metal side oil groove 43 extending along the circumferential direction of the inner peripheral surface is formed on the inner peripheral surface of the upper main bearing metal member 45 over the entire length. That is, the upper main bearing metal member 45 is composed only of the main bearing metal oil groove 44 described above.

  A first oil hole 48 is formed in the upper main bearing metal member 45 at a position corresponding to the lower end opening 27 a of the block oil passage 27. The first oil hole 48 is formed at the center position in the circumferential direction, one end opens into the main bearing metal side oil groove 43, and the other end communicates with the lower end of the block internal oil passage 27.

  The lower main bearing metal member 46 is composed only of the main bearing metal flat portion 42 described above. That is, the main bearing metal side oil groove 43 is not formed on the inner peripheral surface of the lower main bearing metal member 46.

  The control shaft bearing portion 17 includes a main bearing cap side bearing surface 51 having a semicircular cross section formed on the main bearing cap 11, and a control shaft bearing cap side bearing surface 52 having a semicircular cross section formed on the control shaft bearing cap 16. , Is composed of.

  The main bearing cap side bearing surface 32 is open at the lower end of the cap oil passage 28.

  A control shaft bearing metal 53 is mounted on the control shaft bearing portion 17 constituted by the main bearing cap side bearing surface 51 and the control shaft bearing cap side bearing surface 52. That is, the control shaft 7 is rotatably supported by the control shaft bearing portion 17 via the control shaft bearing metal 53.

  As shown in FIG. 3, an oil groove 54 along the circumferential direction is formed on the inner peripheral surface of the control shaft bearing metal 53 over the entire length of the inner peripheral surface. The oil groove 54 is located at the center of the control shaft bearing metal 53 in the axial direction.

  The control shaft bearing metal 53 includes a pair of halved control shaft bearing metal members 55 and 55. The pair of control shaft bearing metal members 55, 55 have the same configuration as parts.

  The control shaft bearing metal member 55 has a semi-cylindrical shape and is mounted so as not to rotate with respect to the main bearing cap side bearing surface 51 and the control shaft bearing cap side bearing surface 52.

  The control shaft bearing metal member 55 has a second oil hole 56 formed at the center in the circumferential direction. One end of the second oil hole 56 opens into the oil groove 54. Further, since the second oil hole 56 is also formed so as to be positioned at the center of the control shaft bearing metal member 55 in the axial direction, no matter how the two control shaft bearing metals 53 are assembled, The second oil hole 56 always matches the oil passage 28 in the cap.

  In other words, since the control shaft bearing metal member 55 is formed so as to be symmetrical with respect to the center position in the circumferential direction, the second oil hole 56 becomes the intended position without considering the orientation at the time of assembly. Assembling work to the main bearing cap side bearing surface 51 and the control shaft bearing cap side bearing surface 52 is facilitated.

  Further, between the inner peripheral surface of the control shaft bearing portion 17 and the outer peripheral surface of the control shaft bearing metal 53, for example, an engaging portion having a claw shape is provided to prevent the control shaft bearing metal 53 from rotating. Although not shown in the figure.

  In the configuration as described above, the high-pressure lubricating oil in the oil gallery 25 is supplied to the crankshaft bearing portion 12 via the in-block oil passage 27. In the crankshaft bearing portion 12, the lubricating oil is guided from the first oil hole 48 of the main bearing metal 41 to the inner peripheral main bearing metal side oil groove 43, and the sliding surface between the crankshaft 9 and the main bearing metal 41 is Lubricated.

  On the other hand, a part of the lubricating oil supplied to the crankshaft bearing portion 12 is guided from the cylinder block side oil groove 33 to the main bearing cap side oil groove 34 on the outer peripheral side of the main bearing metal 41. The lubricating oil introduced into the main bearing cap side oil groove 34 enters the cap internal oil passage 28 and is supplied to the control shaft bearing portion 17.

  In the control shaft bearing portion 17, the lubricating oil is guided from the second oil hole 56 of the control shaft bearing metal 53 to the oil groove 54 on the inner peripheral side, and the control shaft 7, the control shaft bearing metal 53, The sliding surface is reliably lubricated over the entire circumference.

  Thus, in the present embodiment, since the lubricating oil is supplied from the oil gallery 25 of the cylinder block 10 to the control shaft bearing portion 17 via the crankshaft bearing portion 12, the control shaft bearing cap 16 is not necessarily provided with the beam structure. Therefore, the degree of freedom in design is increased and the configuration of the oil passage is simplified.

  Further, since the main bearing metal side oil groove 43 is not formed on the entire inner peripheral surface of the main bearing metal 41, the rigidity of the main bearing metal 41 is relatively improved, and consequently the rigidity of the crankshaft bearing portion 12 is increased. It can be improved relatively. Therefore, even if the load input from the crankshaft 9 increases with the increase in the output of the internal combustion engine, the rigidity required for the crankshaft bearing portion 12 can be ensured.

  The crankshaft bearing portion 12 has a relatively low supporting force with respect to the main bearing metal 41 at the position where the cylinder block side oil groove 33 and the main bearing cap side oil groove 34 are formed. If the rigidity of the main bearing metal 41 is increased by relatively increasing the thickness in the radial direction of the 41, the deformation of the main bearing metal 41 due to a decrease in support force can be prevented.

  Further, as indicated by a two-dot chain line in FIG. 3, the main bearing cap side oil groove 34 is formed on one end side in the circumferential direction on the main bearing cap side bearing surface 32 so as not to exceed the center position in the circumferential direction. It is also possible to form. In this case, as shown by a two-dot chain line in FIG. 3, the in-cap oil passage 28 is inclined with respect to the central axis L of the cylinder 18 so that the lower end thereof is opened at the top of the control shaft bearing portion 17. it can.

  And although not shown in figure, it is also possible to form the oil grooves 33 and 34 in the full length of the cylinder block side bearing surface 31 and the main bearing cap side bearing surface 32, respectively.

DESCRIPTION OF SYMBOLS 1 ... Double link type piston crank mechanism 3 ... Lower link 7 ... Control shaft 9 ... Crank shaft 10 ... Cylinder block 11 ... Main bearing cap 12 ... Crank shaft bearing part 16 ... Control shaft bearing cap 17 ... Control shaft bearing part 21 ... Bulk Head 25 ... Oil gallery 27 ... Block oil passage 28 ... Cap oil passage 31 ... Cylinder block side bearing surface 32 ... Main bearing cap side bearing surface 33 ... Cylinder block side oil groove 34 ... Main bearing cap side oil groove 41 ... Main Bearing metal

Claims (3)

A crankshaft that is rotatably supported via a main bearing metal on a crankshaft bearing composed of a cylinder block and a main bearing cap, a lower link supported by a crankpin of the crankshaft, and a lower link An upper link that connects one end to the piston pin, a control shaft that is rotatably supported by a control shaft bearing that includes the main bearing cap and the control shaft bearing cap, the other end of the lower link, and the above A control link that connects the eccentric shaft portion of the control shaft, an oil passage in the block that is formed inside the cylinder block and extends from an oil gallery of the cylinder block to the crankshaft bearing portion, and the main bearing Formed within cap, the bearing structure of the multilink-type piston crank mechanism for an internal combustion engine having a inside oil passage cap that leads to the control shaft bearing portion from the crank shaft bearing portion,
The crankshaft bearing portion has a main bearing cap side bearing surface formed on the main bearing cap,
An oil groove is formed on the inner peripheral surface of the crankshaft bearing portion along the circumferential direction to which the lower end of the block oil passage and the upper end of the cap oil passage are connected .
2. The bearing structure for a multi-link piston crank mechanism of an internal combustion engine, wherein the oil groove is formed so as not to exceed a center position in a circumferential direction of the main bearing cap side bearing surface .   2. The bearing structure for a multi-link piston crank mechanism for an internal combustion engine according to claim 1, wherein the oil groove is formed on a part of an inner peripheral surface of the crankshaft bearing portion. The crank shaft bearing portion has a cylinder block side bearing surface formed on the cylinder block,
The multi-link type piston for an internal combustion engine according to claim 1 or 2, wherein the oil groove is formed so as to continue from the cylinder block side bearing surface to the main bearing cap side bearing surface. Crank mechanism bearing structure.

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