JP2013256883A - Internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain higher rigidity in a first link side of a rocker arm where a distance between shafts is longer, since the thickness of the rocker arm in a periphery of a rocking support shaft penetration hole along a radial direction of the rocking support shaft penetration is relatively large on the first link side.SOLUTION: A piston-crank mechanism of an internal combustion engine includes a rocker arm 10 rocking around a rocking support shaft. The rocker arm 10 is set in such a manner that a distance L1 from a rocking fulcrum 7 being the center of the rocking support shaft to the center of a connecting part with a first link is longer than a distance L2 from the center of the rocking support shaft 13 to a connecting part with a second link. The rocker arm 10 has one end connected to the first link and the other end connected to the second link, each end bifurcated to support both ends of a connecting pin. In a view in an axial direction of a crankshaft, the rocker arm is formed in such a manner that in a thickness distribution of a rocking support shaft connecting part 22 in a radial direction of the rocking support shaft penetration hole 21, the thickness at the first link 11 side is larger than the thickness at the second link 12 side.

Description

  The present invention relates to a reciprocating internal combustion engine that converts a reciprocating linear motion of a piston into a rotational motion of a crankshaft and transmits it.

  Patent Document 1 previously filed by the present applicant discloses a piston-crank mechanism that mechanically connects a piston and a crank pin via a plurality of link members to convert a reciprocating linear motion of the piston into a rotational motion of the crankshaft. And an internal combustion engine in which the center of rotation of the crankshaft is disposed on the side of the cylinder is disclosed.

  In the internal combustion engine in Patent Document 1, the center of rotation of the crankshaft is arranged on the side of the cylinder, so that the overall height of the internal combustion engine is kept low, and the internal combustion engine is compactly configured as a whole to improve vehicle mountability. I am letting.

JP 2006-52667 A

  However, in such an internal combustion engine, there is room for further improvement in suppressing vibration of the internal combustion engine and improving output by suppressing the deformation of the link member accompanying the movement of the multi-link type piston-crank mechanism. is there.

  The internal combustion engine of the present invention includes a rocker arm that can swing around a fulcrum shaft, a first link connected to one end of the rocker arm, a second link connected to the other end of the rocker arm, and the first link. A piston connected to one end of the second link, and a crankshaft connected to one end of the second link, from the fulcrum shaft to the connecting portion of the rocker arm and the first link as viewed in the axial direction of the crankshaft. Is provided with a piston-crank mechanism that is longer than the distance from the fulcrum shaft to the connecting portion between the rocker arm and the second link. The rocker arm is formed in a bifurcated shape so that one end side of the rocker arm connected to the first link and the other end side of the rocker arm connected to the second link respectively support both ends of the connecting pin. ing.

  The rocker arm passes between the two fork portions of the rocker arm, and is a cross-section by a plane orthogonal to the axial direction of the crankshaft, the center of the fulcrum shaft through-hole through which the fulcrum shaft passes, the rocker arm and the rocker arm A straight line passing through the center of the connecting portion with the first link is defined as a first straight line, and a straight line passing through the center of the fulcrum shaft through hole and the center of the connecting portion between the rocker arm and the second link is defined as a second straight line. The cross-sectional area of the outer periphery of the fulcrum shaft through-hole when a straight line that bisects the included angle formed by the first straight line and the second straight line through the center of the fulcrum shaft through-hole is defined as a third straight line. The cross-sectional area on the first link side of the third straight line is larger than the cross-sectional area on the second link side of the third straight line.

  According to the present invention, in the rocker arm, the thickness around the swing support shaft through hole along the radial direction of the swing support shaft through hole is relatively thick on the first link side. Therefore, in the rocker arm, the rigidity on the first link side where the inter-axis distance becomes long can be increased.

BRIEF DESCRIPTION OF THE DRAWINGS Explanatory drawing which showed typically the internal combustion engine which concerns on this invention. The perspective view of the rocker arm which comprises the internal combustion engine which concerns on this invention. The top view of the rocker arm which comprises the internal combustion engine which concerns on this invention. Sectional drawing along the AA line of FIG. Explanatory drawing which showed typically an example of link arrangement | positioning of a piston-crank mechanism. Explanatory drawing which showed typically an example of link arrangement | positioning of a piston-crank mechanism.

  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 an internal combustion engine 1 according to the present invention, and is an explanatory view corresponding to a cross section of the internal combustion engine 1 as viewed in the crankshaft axial direction.

  The reciprocating internal combustion engine 1 has a configuration in which a crankshaft 4 is disposed on the side of a cylinder 3 in which a piston 2 is slidably accommodated.

  In the internal combustion engine 1, the piston 2 and the crankpin 5 of the crankshaft 4 are mechanically linked by a plurality of link members, and the reciprocating linear motion of the piston 2 in the cylinder 3 is converted into the rotational motion of the crankshaft 4. A multi-link type piston-crank mechanism 6 is provided.

  The piston-crank mechanism 6 includes an elongated rocker arm 10 that can swing around a swing fulcrum 7, an elongated rod-shaped first link 11 that connects one end of the rocker arm 10 and the piston 2, and the other end of the rocker arm 10. It has an elongated rod-like second link 12 that connects the crankpin 5 of the crankshaft 4.

  For example, the rocker arm 10 is rotatably attached to a swing support shaft 13 as a fulcrum shaft fixed to a cylinder block (not shown) of the internal combustion engine 1. Swings as follows.

  The lower end of the first link 11 and one end of the rocker arm 10 are connected by a first connecting pin 14 so as to be relatively rotatable. The piston 2 and the upper end of the first link 11 are connected by a piston pin 15 so as to be relatively rotatable. The other end of the rocker arm 10 and the lower end of the second link 12 are connected to each other by a second connecting pin 16 having a larger diameter than the first connecting pin 14 so as to be relatively rotatable. The first link 11, the rocker arm 10, and the second link 12 connected in series are arranged in a substantially U shape as a whole when viewed in the crankshaft axial direction, and are positioned between the piston 2 and the crankshaft 4. The cylinder wall portion 17 is surrounded by these link members from three sides.

  1 is the center of rotation of the crankshaft 4, 5a is the center of the crankpin 5, 14a is the center of the first connecting pin 14, and 15a is the piston pin 15 in FIG. 1, 16 a in FIG. 1 is the center of the second connecting pin 16. Further, 18 in FIG. 1 is an intake valve, and 19 in FIG. 1 is an exhaust valve.

  Here, as shown in FIGS. 2 and 3, the rocker arm 10 in the present embodiment is formed in a bifurcated shape so that one end side to which the first link 11 is connected supports both ends of the first connecting pin 14. In addition, the other end side to which the second link 12 is connected is formed in a bifurcated shape so as to support both ends of the second connection pin 16.

  In other words, the rocker arm 10 has a cylindrical swing support shaft connecting portion 22 provided in a swing support shaft through hole 21 through which the swing support shaft 13 passes, and a first link connection that supports both ends of the first connection pin 14. The portion 23 and the second link connecting portion 24 that supports both ends of the second connecting pin 16 are roughly configured.

  The first link connecting portion 23 has a pair of one end-side facing walls 25 and 25 that protrude from the swing support shaft connecting portion 22 and face each other, and are formed on the one end-side facing walls 25 and 25, respectively. Both ends of the first connecting pin 14 are supported by the insertion holes 26 and 26.

  The second link connecting portion 24 has a pair of opposite-side opposite walls 27 and 27 that protrude from the swing support shaft connecting portion 22 and face each other, and are formed on the opposite-end-side opposing walls 27 and 27, respectively. Both ends of the second connection pin 16 are supported by the connection pin insertion holes 28 and 28.

  In such a piston-crank mechanism 6, in order to increase the piston stroke, the distance from the swing support shaft 13 to the first connection pin 14 is larger than the distance from the swing support shaft 13 to the second connection pin 16. Is also set to be longer. Therefore, the rocker arm 10 has an inter-axis distance from the swing support shaft 13 to the connection portion with the first link 11 by the first connection pin 14, and the second link 12 by the second connection pin 16 from the swing support shaft 13. Thus, the first link 11 side is more easily deformed than the swing support shaft 13.

  Therefore, in the present embodiment, the thickness on the first link 11 side of the thickness of the swing support shaft connecting portion 22 along the radial direction of the swing support shaft through hole 21 is the thickness on the second link 12 side. It is formed to be thicker than the thickness.

  Referring to FIG. 4 in detail, a straight line passing through the center of the swing support shaft through hole 21 (swing support point 7) and the center of the first connection pin insertion hole 26 (center 14a of the first connection pin 14). A straight line passing through the center of the swing support shaft through hole 21 (swing support point 7) and the center of the second connecting pin insertion hole 28 (center 16a of the second connecting pin 16) is defined as the first straight line L1. When a straight line that divides the included angle between the first straight line L1 and the second straight line L2 into two is defined as a third straight line L3. Of the cross-sectional area of the swing support shaft coupling portion 22 that is the cross-sectional area on the outer peripheral side of the swing support shaft through hole 21, the cross-sectional area on the first link 11 side with respect to the third straight line L3 is more than the third straight line L3 It is formed to be larger than the cross-sectional area on the second link 12 side. Here, FIG. 4 is a cross-sectional view taken along the line AA in FIG. 3, which is orthogonal to the axial direction of the swing support shaft through hole 21, between one end side opposing walls 25, 25 and opposite the other end side. It is a cross section by a plane located between the walls 27, 27.

  Further, as shown in FIG. 4, the distance from the center of the swing support shaft through hole 21 (swing support point 7) to the center of the first connecting pin insertion hole 26 (center 14 a of the first connecting pin 14). The distance from the center of the swing support shaft through hole 21 (swing support point 7) to the center of the second connection pin insertion hole 28 (center 16a of the first connection pin 16) is D2, and the swing support shaft is penetrated. Of the thicknesses along the radial direction of the fulcrum shaft through hole 21 on the outer periphery of the hole 21, if the thickness on the first straight line L1 is D3 and the thickness on the second straight line L2 is D4, the rocker arm 10 is It is formed so that D1 / D2 <D3 / D4.

  As a result, the rocker arm 10 has a relatively thick wall around the swing support shaft through hole 21 along the radial direction of the swing support shaft through hole 21 on the first link 11 side. Therefore, in the rocker arm 10, the rigidity on the first link 11 side where the inter-axis distance becomes long can be increased.

  In the present embodiment, as shown in FIG. 3, the interval C1 between the one end side opposing walls 25, 25, which is the interval inside the bifurcated portion on one end side of the rocker arm 10, is the inner side of the bifurcated portion on the other end side. It is formed so as to be smaller than the interval C2 between the other end side opposing walls 27, 27, which is the interval, and the wall thickness T1 of the one end side opposing wall 25 is thicker than the wall thickness T2 of the other end side opposing wall 27. It is formed as follows. Further, as shown in FIG. 4, the first connection pin insertion hole 26 that supports both ends of the first connection pin 14 has a smaller diameter than the second connection pin insertion hole 28 that supports both ends of the second connection pin 16. The length of the first connection pin 14 is set to be shorter than that of the second connection pin 16 as shown in FIG.

  As described above, the distance C1 between the one end side facing walls 25, 25 is relatively reduced, the thickness T1 of the one end side facing wall 25 is relatively increased, or the hole diameter of the first connecting pin insertion hole 26 is increased. Reducing the size of the first connecting pin 14 and reducing the length of the first connecting pin 14 are also effective in improving the rigidity of the rocker arm 10 on the first link 11 side relative to the swing support shaft 13.

  Further, the load that the cylinder block receives from the piston-crank mechanism 6 becomes maximum near the top dead center and the bottom dead center.

  FIG. 5 is an explanatory view schematically showing the link arrangement in the vicinity of the top dead center where the load received by the cylinder block from the piston-crank mechanism 6 is maximum. As shown in FIG. 5, as viewed in the crankshaft axial direction, a straight line passing through the second connecting pin center 16a and the swing fulcrum 7 and a straight line passing through the second connecting pin center 16a and the crank pin center 5a are sandwiched. When the angle is θ1, the piston-crank mechanism 6 has the minimum included angle θ1 at the top dead center and the maximum included angle θ1 at the bottom dead center.

  Loads are input to the cylinder block from the swing support shaft 13 of the piston-crank mechanism 6 and the crankshaft 4. The load R1 input from the swing support shaft 13 to the cylinder block is the moment of inertia of the rocker arm 10. However, the load R <b> 2 input from the crankshaft 4 to the cylinder block is affected by the moment of inertia of the rocker arm 10. Therefore, the load R2 input from the crankshaft 4 is larger than the load R1 input from the swing support shaft 13. The direction in which the load R1 acts and the direction in which the load R2 acts are opposite to each other.

  When the center of gravity position G of the rocker arm 10 does not coincide with the center position (swinging fulcrum 7) of the swing support shaft 13, a load Rc is generated at the center of gravity position G of the rocker arm 10, and the load resulting from this load Rc. R3 and R4 are further input from the swing support shaft 13 and the crankshaft 4 to the cylinder block. That is, when the straight line that passes through the center position of the swing support shaft 13 (swing support point 7) and is orthogonal to the second straight line L2 is the fourth straight line L4 in the crankshaft axial view, the fourth straight line By setting the center of gravity G of the rocker arm 10 to be positioned closer to the piston than L4, a load R3 resulting from the load Rc generated at the center of gravity G of the rocker arm 10 is input from the swing support shaft 13 to the cylinder block. A load R4 resulting from the load Rc is input from the crankshaft 4 to the cylinder block.

  The load R3 has the same direction and the same magnitude as the load Rc as viewed in the crankshaft axial direction. The load R4 acts in the opposite direction to the load R3 when viewed from the crankshaft axis direction. The load R4 is compared with the distance from the center of the swing support shaft 13 (swing support point 7) to the center of gravity G of the rocker arm 10. The distance from the center of the moving support shaft 13 (swing support point 7) to the center 16a of the second connecting pin 16 becomes smaller.

  That is, the load R1 and the load R3 are input from the swing support shaft 13 to the cylinder block, and the input from the swing support shaft 13 is relatively opposite to the load R1 from the crankshaft 4. A large load R2 and a load R4 that is relatively smaller than the load R3 are input.

  Accordingly, when the center of gravity G of the rocker arm 10 is set to be located on the piston side with respect to the fourth straight line L4 in the crankshaft axial view, the load that the cylinder block receives from the piston-crank mechanism 6 is maximized. In the vicinity of the dead center, the entire cylinder block can be set so that the input of the load from the swing support shaft 14 and the input of the load from the crankshaft 4 are offset from each other. The input of the load from the piston-crank mechanism 6 to receive can be reduced.

  In addition, by setting the center of gravity G of the rocker arm 10 to be located on the piston side of the fourth straight line L4 in the crankshaft axial view, the load that the cylinder block receives from the piston-crank mechanism 6 is maximized. Also in the vicinity of the dead center, as in the case of the vicinity of the top dead center where the load received by the cylinder block from the piston-crank mechanism 6 is maximum, the load R1 and the load R3 are input from the swing support shaft 13, and the crankshaft 4 , A load R2 that is relatively larger than the load R1 and a load R4 that is relatively smaller than the load R3 are input in the opposite direction to the input from the swing support shaft 13. The directions of the loads R <b> 1 to R <b> 4 are opposite to those in the vicinity of the top dead center.

  Therefore, when the center of gravity G of the rocker arm 10 is set to be located on the piston side of the fourth straight line L4 in the crankshaft axial view, the load that the cylinder block receives from the piston-crank mechanism 6 is maximized. Even in the vicinity of the dead center, when the entire cylinder block is viewed, it is possible to set the input of the load from the swing support shaft 14 and the input of the load from the crankshaft 4 to cancel each other. The input of the load from the piston-crank mechanism 6 received by can be reduced.

  That is, the maximum value of the load input from the piston-crank mechanism 6 to the cylinder block is set by setting the center of gravity G of the rocker arm 10 on the piston side with respect to the fourth straight line L4 in the crankshaft axial view. It becomes possible to make it relatively small.

  In FIG. 6, the distance from the center of the swing support shaft 13 (swing support point 7) to the center of gravity G of the rocker arm 10 is equal to the distance from the center of the swing support shaft 13 to the center 16a of the second connecting pin 16. It is explanatory drawing which showed typically the link arrangement | positioning in the vicinity of the top dead center of the piston-crank mechanism 6 in the case.

  When the distance from the center of the swing support shaft 13 (the swing support point 7) to the center of gravity G of the rocker arm 10 is equal to the distance from the center of the swing support shaft 13 to the center 16a of the second connecting pin 16, the rocker arm 10 The magnitude of the load R5 acting on the connecting portion of the rocker arm 10 and the second link 12 due to the load Rc generated at the center of gravity position G is input from the swing support shaft 13 to the cylinder block due to the load Rc. Is equal to the load R3.

  In the piston-crank mechanism 6, the distance from the center of the swing support shaft 13 (swing support point 7) to the center of gravity G of the rocker arm 10 is from the center of the swing support shaft 13 to the center 16 a of the second connecting pin 16. If the distance becomes longer, the load R5 opposite to the load R3 becomes larger than the load R3 input from the swing support shaft 13 to the cylinder block. The load R5 is input from the crankshaft 4 to the cylinder block via the second link 12.

  Therefore, when the center of gravity position G of the rocker arm 10 is set to the piston side with respect to the fourth straight line L4 as viewed from the crankshaft axis direction, the center of gravity G of the rocker arm 10 from the center of the swing support shaft 13 (swing support point 7). Is set to be shorter than the distance from the center of the swing support shaft 13 to the center 16a of the second connecting pin 16, thereby reducing the load input from the piston-crank mechanism 6 to the cylinder block. can do.

DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine 2 ... Piston 3 ... Cylinder 4 ... Crankshaft 4a ... Crankshaft rotation center 5 ... Crankpin 5a ... Crankpin center 6 ... Piston-crank mechanism 7 ... Swing fulcrum 10 ... Rocker arm 11 ... First link 12 ... 2nd link 13 ... Swing support shaft 14 ... 1st connection pin 14a ... 1st connection pin center 15 ... Piston pin 15a ... Piston pin center 16 ... 2nd connection pin 16a ... 2nd connection pin center 17 ... Cylinder wall part 18 ... Intake valve 19 ... Exhaust valve 21 ... Oscillating spindle through hole 22 ... Oscillating spindle connecting part 23 ... First link connecting part 24 ... Second link connecting part 25 ... One end side facing wall 26 ... First connecting pin insertion Hole 27 ... opposite end side wall 28 ... second connecting pin insertion hole

Claims (9)

A rocker arm having a fulcrum shaft through-hole through which the fulcrum shaft passes, a rocker arm swingable about the fulcrum shaft, a first link connected to one end of the rocker arm via a first connection pin, and the other rocker arm A crank shaft connected to one end of the first link, a piston connected to one end of the first link, and a crankshaft connected to one end of the second link. A piston-crank in which the distance from the fulcrum shaft to the connecting portion between the rocker arm and the first link is longer than the distance from the fulcrum shaft to the connecting portion between the rocker arm and the second link in an axial view. Equipped with a mechanism
In the internal combustion engine in which one end side of the rocker arm connected to the first link and the other end side of the rocker arm connected to the second link are formed in a bifurcated shape so as to support both ends of the connecting pin, respectively. ,
The rocker arm passes between the two fork portions at both ends of the rocker arm, and is a cross section by a plane orthogonal to the axial direction of the crankshaft, and the center of the fulcrum shaft through hole and the connecting portion of the rocker arm and the first link A straight line passing through the center is defined as a first straight line, a straight line passing through the center of the fulcrum shaft through hole and the center of the connecting portion between the rocker arm and the second link is defined as a second straight line, and the center of the fulcrum shaft through hole When the straight line that bisects the included angle formed by the first straight line and the second straight line is defined as a third straight line, the cross-sectional area on the outer peripheral side of the fulcrum shaft through hole is greater than the third straight line. An internal combustion engine wherein the cross-sectional area on the first link side is larger than the cross-sectional area on the second link side than the third straight line.   The rocker arm is a cross section by a plane perpendicular to the axial direction of the crankshaft passing between the bifurcated portions at both ends of the rocker arm, and the distance from the center of the fulcrum shaft through hole to the center of the connecting portion with the first link D1 is the distance from the center of the fulcrum shaft through hole to the center of the connecting portion with the second link, and the thickness of the outer periphery of the fulcrum shaft through hole along the radial direction of the fulcrum shaft through hole is 2. The structure according to claim 1, wherein D1 / D2 <D3 / D4 is formed, where D3 is a thickness on the first straight line and D4 is a thickness on the second straight line. The internal combustion engine described.   3. The internal combustion engine according to claim 1, wherein the rocker arm is formed such that an inner space of the bifurcated portion on one end side is smaller than an inner space of the bifurcated portion on the other end side. The diameter of the first connecting pin is smaller than the diameter of the second connecting pin,
The hole diameter of the one end side connection pin insertion hole that supports both ends of the first connection pin on one end side of the rocker arm is the other end side connection pin insertion that supports both ends of the second connection pin on the other end side of the rocker arm. The internal combustion engine according to any one of claims 1 to 3, wherein the internal diameter engine is smaller than a hole diameter.   One end side and the other end side of the rocker arm are formed in a bifurcated shape by having a pair of opposing walls facing each other, and the thickness of the opposing wall of the bifurcated portion on one end side is the same as that of the bifurcated portion on the other end side. The internal combustion engine according to any one of claims 1 to 4, wherein the internal combustion engine is formed to be thicker than a wall thickness of the opposing wall.   The internal combustion engine according to claim 1, wherein the first connection pin is shorter than the second connection pin.   The internal combustion engine according to any one of claims 1 to 6, wherein the center of gravity of the rocker arm is located closer to the piston than the fulcrum shaft as viewed in the crankshaft axial direction.   The center of gravity of the rocker arm is located on the piston side with respect to a straight line that passes through the center of the fulcrum shaft through hole and is orthogonal to the second straight line as viewed in the crankshaft axial direction. The internal combustion engine described in 1.   The distance from the fulcrum shaft to the center of gravity of the rocker arm is smaller than the distance from the fulcrum shaft to the connecting portion of the rocker arm and the second link in the crankshaft axial view. 9. The internal combustion engine according to claim 8, wherein

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