JP2019132176A - Lower link in variable compression ratio mechanism of internal combustion engine - Google Patents

Abstract

To suppress the deformation of a lower link resulting from a combustion load.SOLUTION: A lower link 7 is constituted while being split into two components of a lower link upper 7A including upper pin bearing parts 12 and a lower link lower 7B including control pin bearing parts 13, in a split face 14 passing through a center of a crank pin bearing part 11. The upper pin bearing parts 12 are formed at both of a pair of one-end side protrusive pieces 16 which oppose each other while separating from each other. A pair of the one-end side protrusive pieces 16 are located at one end side of the lower link 7, and constitute a part of the lower link upper 7A. The lower link upper 7A is formed in such a manner that a height t1 thereof along an input direction of an input load to the lower link 7 resulting from a combustion load becomes higher than a height t2 of the lower link lower 7B along the input direction of the input load to the lower link 7 resulting from the combustion load.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a lower link in a variable compression ratio mechanism of an internal combustion engine using a multi-link type piston crank mechanism.

  As a prior art in which a piston pin and a crank pin of a reciprocating internal combustion engine are connected by a multi-link type piston crank mechanism, Patent Document 1 previously proposed by the present applicant is known. This includes an upper link connected to the piston pin of the piston, a lower link connecting the upper link and the crank pin of the crankshaft, one end supported to be swingable to the engine body side, and the other end to the lower link. A control link coupled to the link. The upper link and the lower link are rotatably connected to each other via an upper pin, and the control link and the lower link are rotatably connected to each other via a control pin.

  The upper link in such a multi-link type piston crank mechanism has an annular pin boss portion at each end of a rod-shaped rod, and one pin boss portion is connected to the piston pin, and the other pin boss The part is connected to the upper pin. Both ends of the upper pin are supported by a pair of upper pin pin bosses formed in a bifurcated shape at one end of the lower link, and the other pin boss part of the upper link is rotatably fitted in the center in the axial direction. To do.

  The control link has an annular pin boss part at each end of the rod-shaped rod. One pin boss part is supported swingably on the engine body side, and the other pin boss part is connected to the control pin. Is done.

  The control pin is supported at both ends by a pair of control pin pin bosses formed in a bifurcated shape at the other end of the lower link, and the other pin boss part of the control link can be rotated at the center in the axial direction. To fit.

  The lower link is divided into a lower link upper including a pin boss portion for an upper pin and a lower link lower including a pin boss portion for a control pin along a document surface passing through the center of the crank pin bearing portion into which the crank pin is fitted. Yes.

  The lower link upper and the lower link lower are fastened by two bolts arranged on both sides of the crankpin bearing portion.

Japanese Patent Laid-Open No. 2006-196888

  In such a multi-link type piston crank mechanism, when the distance between the center of the upper pin and the center of the crank pin becomes longer, the moment due to the input load from the crank pin increases.

  Therefore, there is a possibility that the lower link upper is deformed and a mouth opening occurs in the fastening surface between the lower link upper and the lower link lower.

  The present invention is a lower link in a variable compression ratio mechanism of an internal combustion engine using a multi-link type piston crank mechanism. The lower link includes a substantially central crank pin bearing portion into which the crank pin is fitted, an upper pin bearing portion on one end side that holds the upper pin, and a control pin bearing portion on the other end side that holds the control pin. A lower link upper including the upper pin bearing and a lower link lower including the control pin bearing are divided along a split surface passing through the center of the crank pin bearing.

  The upper pin bearing portion is formed on a pair of one end side protruding pieces that are opposed to each other and that constitute one end side of the lower link.

  The control pin bearing portion is formed on a pair of opposite end protruding pieces that constitute the other end side of the lower link.

  The lower link upper has a height along the input direction of the input load to the lower link caused by the combustion load, and the lower link lower along the input direction of the input load to the lower link caused by the combustion load. It is formed to be higher than the height.

  ADVANTAGE OF THE INVENTION According to this invention, the rigidity of a lower link upper can be improved and a deformation | transformation of the lower link upper at the time of the input of a combustion load can be suppressed.

Explanatory drawing which showed typically the component of the variable compression ratio mechanism to which the lower link which concerns on this invention was applied. The front view of the lower link which concerns on this invention. The top view of the lower link which concerns on this invention. Sectional drawing along the AA line of FIG. Sectional drawing along the BB line of FIG. Explanatory drawing which shows the lower link which received the combustion load and deform | transformed.

  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 components of a variable compression ratio mechanism 1 included in a variable compression ratio internal combustion engine to which a lower link 7 of the present invention is applied.

  The variable compression ratio internal combustion engine constitutes an engine unit together with a transmission (not shown), for example, and is supported by a vehicle body (not shown) via a plurality of support members such as an engine mount (not shown) and a torque rod.

  The variable compression ratio mechanism 1 includes an upper link 4 having one end connected to a piston 2 via a piston pin 3, and is connected to the other end of the upper link 4 via an upper pin (first connection pin) 5 and a crankshaft. 6, the lower link 7 connected to the crank pin 6 a, the control link 9 having one end connected to the lower link 7 via the control pin (second connection pin) 8, and the other end of the control link 9. And a control shaft 10 having an eccentric shaft portion 10a.

  That is, the variable compression ratio mechanism 1 uses a multi-link piston crank mechanism in which the piston 2 and the crank pin 6a of the crankshaft 6 are linked by a plurality of links.

  One end of the upper link 4 is rotatably attached to the piston pin 3, and the other end is rotatably connected to one end side of the lower link 7 by the upper pin 5.

  The crankshaft 6 includes a plurality of crank pins 6a and a journal portion 6b, and the journal portion 6b is rotatably supported by a main bearing (not shown) of a cylinder block (not shown). The crank pin 6a is eccentric by a predetermined amount from the journal portion 6b, and a lower link 7 is rotatably connected thereto.

  One end of the control link 9 is rotatably connected to the other end side of the lower link 7 by a control pin 8, and the other end is rotatably attached to the eccentric shaft portion 10 a of the control shaft 10. The upper pin 5 and the control pin 8 are press-fitted and fixed to the lower link 7.

  The control shaft 10 is disposed in parallel with the crankshaft 6 and is rotatably supported by, for example, a cylinder block (not shown).

  That is, the other end of the control link 9 that is rotatably connected to the eccentric shaft portion 10a of the control shaft 10 is swingably supported on the engine body side.

  The variable compression ratio mechanism 1 oscillates the control link 9 that regulates the degree of freedom of the lower link 7 by changing the position of the eccentric shaft portion 10a by rotating the control shaft 10. The variable compression ratio mechanism 1 swings the control link 9 to change the position of the piston 2 at the top dead center, thereby changing the mechanical compression ratio of the internal combustion engine.

  The control shaft 10 is rotationally driven by, for example, an actuator made of an electric motor.

  The lower link 7 will be described in detail with reference to FIGS. FIG. 2 is a front view of the lower link 7. FIG. 3 is a plan view of the lower link 7. 4 is a cross-sectional view taken along line AA in FIG. FIG. 5 is a cross-sectional view taken along line BB in FIG.

  As shown in FIG. 2, the lower link 7 has a cylindrical crankpin bearing portion 11 fitted in the crankpin 6a at the center. In addition, the lower link 7 has a pair of upper pin bearing portions 12 and a pair of control pin bearing portions 13 at positions that are substantially 180 ° opposite to each other with the crankpin bearing portion 11 interposed therebetween.

  The lower link 7 has a parallelogram shape close to a rhombus as a whole. The lower link 7 is formed by dividing into two parts, a lower link upper 7A including the upper pin bearing portion 12 and a lower link lower 7B including the control pin bearing portion 13, on a split surface 14 passing through the center of the crankpin bearing portion 11. Has been.

  The dividing surface 14 is inclined with respect to the lower link width direction along a straight line connecting the center of the upper pin bearing portion 12 and the center of the control pin bearing portion 13.

  In the present embodiment, the upper pin bearing portion 12 side in the lower link width direction is one end side of the lower link 7, and the control pin bearing portion 13 side in the lower link width direction is the other end side of the lower link 7.

  The lower link upper 7A and the lower link lower 7B are fastened to each other by a pair of bolts 15 inserted in opposite directions after the crank pin bearing portion 11 is fitted into the crank pin 6a.

  In other words, the lower link upper 7 </ b> A and the lower link lower 7 </ b> B are fastened by the two bolts 15 disposed on both sides of the crankpin bearing portion 11. The lower link upper 7A and the lower link lower 7B may be fastened by two or more bolts 15.

  The lower link 7 is formed so that the distance from the center of the upper pin bearing portion 12 to the axis of the crankpin bearing portion 11 is equal to the distance from the axis of the control pin bearing portion 13 to the axis of the crankpin bearing portion 11. Has been. In other words, the lower link 7 is formed so that the distance from the axis of the upper pin 5 to the axis of the crank pin 6a is equal to the distance from the axis of the control pin 8 to the axis of the crank pin 6a.

  As shown in FIGS. 2 to 5, the upper pin bearing portion 12 is formed on both of a pair of one end side protruding pieces 16 that are spaced apart from each other and face each other. Between the pair of one end side protruding pieces 16, there is a groove portion 17 having a constant width that allows the upper link 4 to swing. The pair of one end side protruding pieces 16 are located on one end side of the lower link 7 and constitute a part of the lower link upper 7A.

  That is, one end side of the lower link 7 is formed in a bifurcated shape so as to sandwich the other end of the upper link 4 by a pair of one end side protruding pieces 16.

  The pair of one end side protruding pieces 16 extend along the axial end surface of the lower link 7.

  The pair of one end side protruding pieces 16 are formed in a mountain shape in which the shape of the upper end surface along the lower link width direction is convex toward the piston side as viewed in the axial direction of the lower link 7. In other words, the pair of one end projecting pieces 16 are formed in a mountain shape in which the shape along the lower link width direction of the upper end surface facing the dividing surface 14 is convex toward the outer peripheral side of the lower link 7. Yes.

  Each of the upper pin bearing portions 12 is a through-hole having a circular cross section disposed on the same axis. The upper pin 5 is press-fitted into the upper pin bearing portion 12.

  The control pin bearing portion 13 is formed on both of a pair of other end side protruding pieces 18 that are spaced apart from each other and face each other. Between the pair of other end side projecting pieces 18, there is a groove portion 19 having a constant width that allows the control link 9 to swing. The pair of other end side protruding pieces 18 are located on the other end side of the lower link 7 and constitute a part of the lower link lower 7B.

  That is, the other end side of the lower link 7 is formed in a bifurcated shape so as to sandwich one end of the control link 9 by the pair of other end side protruding pieces 18.

  The pair of other end side protruding pieces 18 extend along the axial end surface of the lower link 7.

  Each control pin bearing portion 13 is a through hole having a circular cross section arranged on the same axis. The control pin 8 is press-fitted into the control pin bearing portion 13.

  In such a multi-link variable compression ratio mechanism 1, when the distance between the center of the upper pin bearing portion 12 and the center of the crank pin bearing portion 11 becomes longer, the moment due to the input load from the crank pin 6a increases.

  Therefore, the lower link 7 may be deformed in the lower link upper 7A as indicated by a broken line in FIG. 6 when a load input due to a combustion load enters from the crank pin 6a.

  That is, the lower link 7 is deformed so that a portion on the outer peripheral side of the crankpin bearing portion 11 protrudes outward in the radial direction of the crankpin due to an input load from the crankpin 6a, and a pair of one end side protruding pieces There is a possibility that 16 may be deformed so as to fall outward in the crankpin axial direction.

  For this reason, the lower link 7 may have a mouth opening on the fastening surface (the dividing surface 14) between the lower link upper 7A and the lower link lower 7B due to the deformation of the lower link upper 7A.

  Therefore, as shown in FIG. 5, the lower link upper 7A in the present embodiment has a height t1 along the input direction of the input load to the lower link 7 caused by the combustion load, and the lower link 7 caused by the combustion load. It is formed so as to be higher than the height t2 of the lower link lower 7B along the input direction of the input load.

  In other words, in the lower link upper 7A, the height t1 along the input direction of the combustion load acting on the lower link 7 from the crank pin 6a is along the input direction of the combustion load acting on the lower link 7 from the crank pin 6a. The lower link lower 7B is formed to be higher than the height t2.

  In addition, the arrow P in FIG. 5 has shown the direction of the input load to the lower link 7 resulting from the maximum combustion load. A line segment Q indicated by a broken line in FIG. 5 is obtained by extending the lower end of the arrow P.

  Thereby, the rigidity of the lower link upper 7A can be increased, and the deformation of the lower link upper 7A due to the combustion load can be suppressed.

  In other words, even if the input load from the crank pin 6a increases, the deformation of the lower link upper 7A can be suppressed, and a mouth opening occurs on the fastening surface (the dividing surface 14) between the lower link upper 7A and the lower link lower 7B. Can be suppressed.

  Further, the pair of one end side protruding pieces 16 are formed in a mountain shape in which the shape along the lower link width direction of the upper end surface facing the dividing surface 14 is convex toward the outer peripheral side of the lower link 7. Therefore, the height t1 along the input direction of the input load to the lower link 7 caused by the combustion load can be set relatively high.

  The wall thickness on the outer peripheral side of the crankpin bearing portion 11 is formed such that the thickness along the input direction of the input load to the lower link 7 due to the combustion load is thicker on the lower link upper 7A side than on the lower link lower 7B side. ing.

  That is, the wall thickness t3 along the input direction of the combustion load of the outer peripheral portion of the crank pin bearing portion 11 in the lower link upper 7A is greater than the wall thickness t4 along the input direction of the combustion load of the crank pin bearing portion 11 in the lower link lower 7B. Is also formed thick.

  Also by this, the rigidity of the lower link upper 7A can be increased, and the deformation of the lower link upper 7A due to the combustion load can be suppressed.

  Note that the slope of the arrow P in FIG. 5 described above varies depending on the compression ratio set by the variable compression ratio mechanism 1. In the embodiment described above, as an example, the input load (maximum input load) due to the combustion load (maximum combustion load) at the minimum compression ratio within the compression ratio range that can be set by the variable compression ratio mechanism 1 is applied. Along with this, the height and thickness of the lower link upper 7A are set, but the present invention is not limited to this. That is, the height t1 of the lower link upper 7A is increased along the direction in which the input load acts due to the combustion load having a predetermined compression ratio within the compression ratio range that can be set by the variable compression ratio mechanism 1, and the lower link is increased. You may make it thicken the wall thickness t3 of the outer peripheral part of the crankpin bearing part 11 in the upper 7A.

DESCRIPTION OF SYMBOLS 1 ... Variable compression ratio mechanism 4 ... Upper link 5 ... Upper pin 6 ... Crank shaft 6a ... Crank pin 7 ... Lower link 7A ... Lower link upper 7B ... Lower link lower 8 ... Control pin 9 ... Control link 11 ... Crank pin bearing part 12 ... Upper pin Bearing part 13 ... Control pin bearing part 14 ... Dividing surface 16 ... One end side protruding piece 18 ... Other end side protruding piece

Claims (4)

An upper link having one end connected to the piston via a piston pin;
A lower link connected to the other end of the upper link via an upper pin, and connected to a crankpin of the crankshaft;
A control link having one end swingably supported on the engine body side and the other end connected to the lower link via a control pin, and the support position of one end of the control link is variable and top dead center The lower link in the variable compression ratio mechanism of an internal combustion engine using a multi-link piston crank mechanism that can change the compression ratio by changing the piston position in
The lower link includes a substantially central crank pin bearing portion into which the crank pin is fitted, an upper pin bearing portion on one end side that holds the upper pin, a control pin bearing portion on the other end side that holds the control pin, And divided into a lower link upper including the upper pin bearing portion and a lower link lower including the control pin bearing portion along a split surface passing through the center of the crank pin bearing portion.
The upper pin bearing portion is formed on a pair of one end side projecting pieces facing each other and constituting one end side of the lower link,
The control pin bearing portion is formed on a pair of opposite-end-side protruding pieces that constitute the other end side of the lower link and that face each other.
The lower link upper is configured such that the height along the input direction of the input load to the lower link due to the combustion load is higher than the height of the lower link lower along the input direction of the input load to the lower link due to the combustion load. A lower link in a variable compression ratio mechanism of an internal combustion engine, wherein the lower link is formed to be higher than the height.   2. The variable compression of the internal combustion engine according to claim 1, wherein the lower link upper is formed in a mountain shape in which an end surface on the piston side of the one end side protruding piece is convex toward the piston side. Lower link in the ratio mechanism.   The outer peripheral side wall thickness of the crank pin bearing part is formed such that the thickness along the input direction of the input load to the lower link due to the combustion load is thicker on the lower link upper side than on the lower link lower side. The lower link in the variable compression ratio mechanism of the internal combustion engine according to claim 1 or 2.   The lower link is formed such that the distance from the axis of the upper pin to the axis of the crank pin is equal to the distance from the axis of the control pin to the axis of the crank pin. The lower link in the variable compression ratio mechanism of the internal combustion engine according to any one of claims 1 to 3.

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