JP2018112129A - Variable compression ratio mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a variable compression ratio mechanism which can improve workability when a connecting rod varies a compression ratio.SOLUTION: A connecting rod has a first connecting rod portion 11 and a second connecting rod portion 21 which are arranged in parallel with the same crank pin 7B and the same piston pin 8. The first connecting rod portion 11 is composed of a small end portion 12 and a first arm portion 13 coupled to the piston pin 8, and a first large end portion 14 and a first coupling pin 15 coupled to the crank pin 7B. The second connecting rod portion 21 is composed of a small end portion 22 and a second arm portion 23 coupled to the piston pin 8, and a second large end portion 24 and a second coupling pin 25 coupled to the crank pin 7B. A actuating mechanism is provided, which relatively rotates the first large end portion 14 and the second large end portion 24 about the crank pin 7B.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a variable compression ratio mechanism.

  Conventionally, a variable compression ratio mechanism capable of changing the compression ratio of an internal combustion engine is known. As this variable compression ratio mechanism, one that changes the effective connecting rod length used in the internal combustion engine and mechanically changes the volume of the combustion chamber when the connecting rod is at compression top dead center (for example, Patent Document 1).

  In the variable compression ratio mechanism described in Patent Document 1, an eccentric lever that is rotatable with respect to the connecting rod body is provided on the small-diameter end bearing eye of the connecting rod body. The eccentric lever has a hole for receiving the piston pin, and when the eccentric lever is rotated by the eccentric rod, the effective connecting rod length to the center of the crank pin and the eccentric lever is changed.

  The eccentric rod is connected to an eccentric lever and a central portion in the axial direction of the connecting rod main body, and the eccentric rod is driven by hydraulic pressure supplied to a hydraulic chamber provided in the connecting rod main body.

JP2015-137768A

  In such a conventional variable compression ratio mechanism, the eccentric lever is provided in the small-diameter end bearing eye, and the eccentric rod is connected to the small-diameter end bearing eye and the central portion of the connecting rod body.

  For this reason, the inertial mass (the mass due to the reciprocating small-diameter end bearing eye, arm portion, eccentric lever, and eccentric rod) increases when the connecting rod reciprocates with the piston due to rotation of the crankshaft. For this reason, the operability when operating the eccentric lever to change the compression ratio is deteriorated.

  The present invention has been made paying attention to the above problems, and can reduce the inertial mass when the connecting rod reciprocates, and can improve the operability when changing the compression ratio. The object is to provide a compression ratio mechanism.

  The present invention includes a connecting rod that connects a piston pin of a piston that reciprocates within a cylinder of an internal combustion engine and a crank pin of a crankshaft that performs rotational motion, and compresses by changing the relative position of the piston pin and the crank pin. A variable compression ratio mechanism that varies the ratio, wherein the connecting rod has a first connecting rod portion and a second connecting rod portion that are installed in parallel with the same crank pin and the same piston pin, The first connecting rod portion includes a first component member and a second component member, and the second connecting rod portion includes a third component member and a fourth component member. Each of the first component member and the third component member is a front A small end portion coupled to the piston pin, and an arm portion extending from the small end portion toward the crank pin, and each of the second component member and the fourth component member is at least the A large end connected to the crankpin, and a connecting pin that slidably connects at least the large end to the arm, and at least the second component and the fourth component; An actuating mechanism is provided for moving the second component member and the fourth component member relative to each other about the crank pin.

  As described above, according to the present invention, the inertial mass when the connecting rod reciprocates can be reduced, and the operability of the variable compression ratio mechanism when the compression ratio is varied can be improved.

FIG. 1 is a configuration diagram of an engine including a variable compression ratio mechanism according to an embodiment of the present invention. FIG. 2 is an exploded perspective view of the connecting rod of the variable compression ratio mechanism according to the embodiment of the present invention. FIG. 3 is a diagram showing a hydraulic path of the variable compression ratio mechanism according to one embodiment of the present invention. FIG. 4 is a view showing a variable compression ratio mechanism according to an embodiment of the present invention, and is a view showing a state of the connecting rod at the time of high compression and at the time of low compression. FIG. 5 is a diagram showing a state of the connecting rod when oil is supplied to the first hydraulic chamber in the variable compression ratio mechanism according to one embodiment of the present invention. FIG. 6 is a cross-sectional view taken along arrow VI-VI in FIG. 7 is a cross-sectional view taken along arrow VII-VII in FIG. FIG. 8 is a view showing a state of the connecting rod when oil is supplied to the second hydraulic chamber in the variable compression ratio mechanism according to one embodiment of the present invention. 9 is a cross-sectional view taken along arrow IX-IX in FIG. FIG. 10 is a cross-sectional view taken along the line XX of FIG. FIG. 11 is a diagram showing the force acting on the connecting rod when the compression force or inertia force due to the combustion pressure acts on the piston in the variable compression ratio mechanism according to one embodiment of the present invention.

A variable compression ratio mechanism according to an embodiment of the present invention includes a connecting rod that connects a piston pin of a piston that reciprocates within a cylinder of an internal combustion engine and a crank pin of a crankshaft that performs rotational motion. A variable compression ratio mechanism that changes a compression ratio by changing a relative position, wherein the connecting rod is provided in parallel with the same crank pin and the same piston pin, and the first connecting rod portion and the second connecting rod. The first connecting rod portion includes a first component member and a second component member, and the second connecting rod portion includes a third component member and a fourth component member. Each of the first component member and the third component member is configured to include a component member. A small end portion connected to the stone pin and an arm portion extending from the small end portion toward the crank pin are provided, and each of the second component member and the fourth component member is connected to at least the crank pin. And a connecting pin that slidably connects at least the large end portion to the arm portion. At least the second component member and the fourth component member have a second configuration around the crank pin. An operating mechanism is provided for moving the member and the fourth component relative to each other.
Thereby, the inertial mass when the connecting rod reciprocates can be reduced, and the operability of the variable compression ratio mechanism when the compression ratio is varied can be improved.

Embodiments of a variable compression ratio mechanism according to the present invention will be described below with reference to the drawings.
1 to 11 are views showing a variable compression ratio mechanism according to an embodiment of the present invention. In any of FIGS. 1 to 11, the up, down, left, and right directions represent the directions viewed from the driver on the vehicle.

First, the configuration will be described.
In FIG. 1, an engine 1 as an internal combustion engine mounted on a vehicle includes a cylinder block 2. A cylinder head 3 is provided in the upper part of the cylinder block 2, and an oil pan 51 (see FIG. 3) in which oil O as hydraulic oil is stored is provided in the lower part of the cylinder block 2.

  A cylinder 4 is formed inside the cylinder block 2. A piston 5 is accommodated in the cylinder 4, and the piston 5 can reciprocate up and down with respect to the cylinder 4.

  The piston 5 is connected to the crankshaft 7 via the connecting rod 6, and the reciprocating motion of the piston 5 is converted to the rotational motion of the crankshaft 7 via the connecting rod 6.

  As many cylinders 4 are provided in the engine 1 as the number of cylinders. In the case of a four-cylinder engine, four cylinders 4 are provided in the engine 1. Of course, the number of cylinders is not limited to four. The engine 1 may be composed of an engine such as a gasoline engine or a diesel engine, but is not limited thereto.

1 and 2, the piston 5 has a piston crown portion 5A and a pair of skirt portions 5B and 5C extending downward from the piston crown portion 5A.
The piston 5 has a pair of piston pin boss portions 5D (showing one of the piston pon boss portions in FIGS. 1 and 2) that extend downward from the piston crown portion 5A and hold the piston pin 8 rotatably.

In FIG. 1, a combustion chamber 9 is formed between the upper surface 5 a of the piston crown portion 5 </ b> A and the inner wall of the cylinder 4 and the bottom surface of the cylinder head 3.
An intake port 3 </ b> A is formed in the cylinder head 3, and air sucked from the intake port 3 </ b> A is introduced into the combustion chamber 9. An exhaust port 3B is formed in the cylinder head 3, and the exhaust gas burned in the combustion chamber 9 is exhausted from the exhaust port 3B.

  In FIG. 3, the crankshaft 7 has a crank journal 7 </ b> A, and the crank journal 7 </ b> A is rotatably supported by the cylinder block 2 via bearings 52 and 53. The crankshaft 7 has a crankpin 7B, and a connecting rod 6 is connected to the crankpin 7B.

  In FIG. 2, the connecting rod 6 includes a divided first connecting rod portion 11 and a second connecting rod portion 21. The first connecting rod portion 11 and the second connecting rod portion 21 are installed in parallel to the same crank pin 7B and the same piston pin 8, and connect the crank pin 7B and the piston pin 8. .

  The first connecting rod portion 11 has a first small end portion 12, a first arm portion 13, and a first large end portion 14. A piston pin 8 is inserted into the first small end portion 12, and the first small end portion 12 is connected to the piston pin 8.

  The first arm portion 13 extends from the first small end portion 12 toward the first large end portion 14. The first large end portion 14 is divided into an upper cap portion 14A and a lower cap portion 14B, and the first arm portion 13 swings to the upper cap portion 14A via the first connecting pin 15. It is connected freely. The first connecting pin 15 may be fixed to the upper cap portion 14 </ b> A, or may be fixed to the first arm portion 13.

  Semicircular metal members 16A and 16B are provided on the inner peripheral surfaces of the upper cap portion 14A and the lower cap portion 14B, respectively. The upper cap portion 14A and the lower cap portion 14B are connected by a bolt 17 in a state where the metal members 16A and 16B are in contact with the outer peripheral surface of the crankpin 7B, and the first large end portion 14 is connected to the metal member 16A. , 16B are slidably connected to the crankpin 7B. The first small end portion 12 and the first arm portion 13 of the present embodiment constitute the first constituent member of the present invention, and the first large end portion 14 and the first connecting pin 15 are the present invention. The 2nd structural member of this is comprised.

  The second connecting rod portion 21 has a second small end portion 22, a second arm portion 23, and a second large end portion 24. The piston pin 8 is inserted into the second small end portion 22, and the second small end portion 22 is connected to the piston pin 8.

  The second arm portion 23 extends from the second small end portion 22 toward the second large end portion 24. The second large end portion 24 is divided into an upper cap portion 24A and a lower cap portion 24B, and the second arm portion 23 swings to the upper cap portion 24A via a second connecting pin 25. It is connected freely. The second connecting pin 25 may be fixed to the upper cap portion 24 </ b> A or may be fixed to the second arm portion 23.

  Semicircular metal members 26A and 26B are provided on the inner peripheral surfaces of the upper cap portion 24A and the lower cap portion 24B, respectively. The upper cap portion 24A and the lower cap portion 24B are connected by a bolt 27 in a state where the metal members 26A and 26B are in contact with the outer peripheral surface of the crankpin 7B, and the second large end portion 24 is connected to the metal member 26A. , 26B, and is slidably connected to the crankpin 7B. The second small end portion 22 and the second arm portion 23 of the present embodiment constitute the third component of the present invention, and the second large end portion 24 and the second connecting pin 25 are the present invention. The 4th structural member of this is comprised.

  In FIG. 3, the first large end portion 14 and the second large end portion 24 are installed between the shoulder portions 7 b of the crankpin 7 </ b> B, and the shoulder portions 7 b when moved in the axial direction of the crankshaft 7. Is positioned in the axial direction of the crankshaft 7.

  In the connecting rod 6 of this embodiment, the first large end portion 14 and the second large end portion 24 rotate relative to each other about the crankpin 7B. At this time, the first arm portion 13 and the second arm portion 23 are connected to the first large end portion 14 and the second large end portion 24 with the first connecting pin 15 and the second connecting pin 25 as fulcrums. Swings against. The relative rotation of this embodiment corresponds to the relative movement of the present invention.

  In FIG. 11, in a state where the first large end portion 14 and the second large end portion 24 are relatively rotated, the first small end portion 12, the first arm portion 13, the second small end portion 22, and the first small end portion 22 The second arm portion 23 is installed such that the first connecting pin 15 and the second connecting pin 25 are equidistant from the piston pin 8. Specifically, the distance R1 from the first connecting pin 15 to the piston pin 8 is equal to the distance R1 from the second connecting pin 25 to the piston pin 8.

  In a state where the first large end portion 14 and the second large end portion 24 are relatively rotated, the first large end portion 14 and the second large end portion 24 are connected to the first connecting pin 15 and the second large end portion 24, respectively. The connecting pins 25 are installed so as to be equidistant from the crankpin 7B. Specifically, the distance R2 from the first connecting pin 15 to the piston pin 8 is equal to the distance R2 from the second connecting pin 25 to the crank pin 7B.

  In FIG. 2, a groove portion 24b is formed in the lower cap portion 24B of the second connecting rod portion 21, and the groove portion 24b extends along the circumferential direction of the crank pin 7B. An operating pin 28 is press-fitted into the lower cap portion 14B of the first connecting rod portion 11, and the operating pin 28 is inserted into the groove portion 24b (see FIGS. 5 to 10).

  6 and 9, the space surrounded by the groove 24 b and the lower cap portion 14 </ b> B constitutes a hydraulic chamber 31. The operating pin 28 moves in the hydraulic chamber 31 so as to partition the hydraulic chamber 31 into a first hydraulic chamber 31A (see FIGS. 5 to 7) and a second hydraulic chamber 31B (see FIGS. 8 to 10). . The operating pin 28 of the present embodiment constitutes the moving member of the present invention.

  Oil passages 32 and 33 communicate with the hydraulic chamber 31. 5 to 7, the oil passage 32 includes oil passages 32A and 32B. The oil passage 32A is formed in the lower cap portion 24B so as to extend along the circumferential direction of the crankpin 7B, and communicates with the first hydraulic chamber 31A.

  The oil passage 32B is formed in the lower cap portion 14B, and communicates the oil passage 32A and the control oil passage 34 (see FIG. 3) formed in the crankshaft 7. The oil passage 32A of this embodiment is always in communication with the oil passage 32B in a state where the first large end portion 14 and the second large end portion 24 are relatively rotated.

The oil passage 33 is formed in the lower cap portion 24B, and communicates the hydraulic chamber 31 and the control oil passage 35 (see FIG. 3) formed in the crankshaft 7.
In FIG. 3, a plurality of control oil passages 34 and 35 and lubricating oil passages 36 and 37 are formed in the crankshaft 7. The control oil passages 34 and 35 communicate with control oil passages 38 and 39 formed in the cylinder block 2.

  One end portions of the lubricating oil passages 36 and 37 communicate with the inner peripheral surfaces of the metal members 16A and 26A, and the other end portions of the lubricating oil passages 36 and 37 are oil holes 52A and 53A of the bearings 52 and 53, respectively. To the lubricating oil passages 40 and 41 formed in the cylinder block 2.

  Part of the lubricating oil passages 36 and 37 between one end and the other end communicates with the inner peripheral surfaces of the bearings 52 and 53. The bearings 52 and 53 rotatably support the crank journal 7A on the cylinder block 2 and have an inner peripheral surface in frictional contact with the crank journal 7A.

  The lubricating oil passages 40 and 41 merge with the lubricating oil passage 42, and the lubricating oil passage 42 communicates with the main oil passage 43. The main oil passage 43 communicates with the oil pan 51. An oil pump 44 is provided in the main oil passage 43, and the oil pump 44 sucks up the oil O stored in the oil pan 51 and supplies it to the lubricating oil passage 42.

The oil supplied to the lubricating oil passage 42 is branched from the lubricating oil passage 42 into the lubricating oil passages 40 and 41, and then the inner peripheral surfaces of the metal members 16A and 26A and the bearings from the lubricating oil passages 36 and 37. 52 and 53 are supplied to the inner peripheral surface.
As a result, the metal members 16A and 26A and the crank pin 7B are lubricated, and the bearings 52 and 53 and the crank journal 7A are lubricated.

  The control oil passages 38 and 39 communicate with the control oil passage 46 and the drain passage 47 via the oil control valve 45. The control oil passage 46 communicates with the main oil passage 43, and the oil O stored in the oil pan 51 is supplied from the main oil passage 43 to the control oil passage 46 by the oil pump 44.

  The oil control valve 45 communicates the control oil passage 46 and the control oil passage 38 with the electromagnetic valve 45A, and a first switching position for communicating the control oil passage 39 and the drain passage 47, and the control oil passage. 46 and the control oil passage 39, and the control oil passage 38 and the drain passage 47 are switched to a second switching position.

  When the oil control valve 45 is switched to the first switching position, the oil in the control oil passage 46 is introduced into the first hydraulic chamber 31A through the control oil passages 38 and 34 and the oil passages 32B and 32A.

  At this time, the oil inside the second hydraulic chamber 31B is discharged to the drain passage 47 through the control oil passages 35 and 39. The oil discharged to the drain passage 47 is returned from the drain passage 47 to the oil pan 51.

  When the oil control valve 45 is switched to the second switching position, the oil in the control oil passage 46 is introduced into the second hydraulic chamber 31B through the control oil passages 39 and 35 and the oil passage 33. At this time, the oil in the first hydraulic chamber 31A is discharged to the drain passage 47 through the oil passages 32A and 32B and the control oil passages 34 and 38.

  As described above, the oil control valve 45 of the present embodiment is configured such that when the hydraulic oil is supplied from the oil pump 44 to one of the first hydraulic chamber 31A and the second hydraulic chamber 31B, The flow of the oil is switched so that the oil is discharged from either one of the second hydraulic chambers 31B.

  When oil is introduced into the first hydraulic chamber 31A, the operating pin 28 moves in the circumferential direction of the crankpin 7B along the hydraulic chamber 31, and the first large end portion 14 and the second large end portion 24 are moved. Rotate relative to the circumferential direction of the crankpin 7B.

  As a result, the first arm portion 13 swings to one side or the other side in the left-right direction with respect to the first large end portion 14 with the first connecting pin 15 as a fulcrum, and the second arm portion 23 is With the second connecting pin 25 as a fulcrum, it swings to one side or the other side in the left-right direction with respect to the second large end portion 24.

  For this reason, the relative position between the piston pin 8 and the crank pin 7B is changed, and the height of the upper surface 5a when the piston 5 moves to the compression top dead center is changed. As a result, the volume of the combustion chamber 9 is varied, and the compression ratio of the engine 1 is varied.

  The oil pump 44 and the oil pan 51 of the present embodiment constitute a hydraulic pressure source of the present invention. The oil passages 32 and 33, the control oil passages 34, 35, 38, and 39, the main oil passage 43, and the control oil passage 46 are provided. Constitutes the oil passage of the present invention. The oil control valve 45 constitutes the hydraulic control valve of the present invention.

  The working pin 28, hydraulic chamber 31, oil passages 32, 33, control oil passages 34, 35, 38, 39, main oil passage 43, oil pump 44, oil control valve 45, control oil passage 46, and The oil pan 51 constitutes the operating mechanism 71 of the present invention.

Next, the operation will be described.
In FIG. 4, when the engine 1 has a high compression ratio, the center of the first connecting pin 15 with respect to the virtual line 61 connecting the center axis C1 of the crankpin 7B and the center axis C2 of the piston pin 8 is shown. An inclination angle of an imaginary line 62 connecting the axis C3 and the central axis C1 of the crankpin 7B is θ1.

  When the engine 1 has a low compression ratio, the center axis C3 of the first connecting pin 15 and the crank are connected to a virtual line 61 connecting the center axis C1 of the crank pin 7B and the center axis C2 of the piston pin 8. The inclination angle θ2 of the virtual line 62 connecting the central axis C1 of the pin 7B is larger than the inclination angle θ1 at the time of high compression.

  When the engine 1 has a high compression ratio, the upper surface 5a of the piston 5 when the piston 5 is at the compression top dead center is higher by α than the upper surface 5a of the piston 5 when the engine 1 has a low compression ratio. Located in. As a result, the volume of the combustion chamber 9 is reduced as compared with the low compression ratio, resulting in a high compression ratio.

  When the engine 1 is changed from the high compression ratio to the low compression ratio, the oil control valve 45 is switched to the second switching position. At this time, the oil in the control oil passage 46 is introduced into the second hydraulic chamber 31B through the control oil passages 39 and 35 and the oil passage 33 by the oil pump 44.

  As a result, the operating pin 28 moves to the right in FIGS. 8 and 9 by the pressure of the oil introduced into the second hydraulic chamber 31B, and the first large end portion 14 moves in the circumferential direction of the crank pin 7B. Rotate counterclockwise along

  Therefore, in FIG. 4, the first large end portion 14 rotates relative to the second large end portion 24 in the counterclockwise direction by θ2−θ1 and the second large end portion 24 becomes the first large end portion 24. It rotates relative to the end portion 14 in the clockwise direction by θ2-θ1 (see the connecting rod 6 having a low compression ratio in FIG. 4).

  At this time, the relative position between the piston pin 8 and the crank pin 7B is changed, that is, the effective connecting rod length, which is the distance between the center axis C1 of the crank pin 7B and the center axis C2 of the piston pin 8, is a high compression ratio. Shorter than As a result, the volume of the combustion chamber 9 increases as compared with the high compression ratio, and becomes a low compression ratio.

  On the other hand, when the engine 1 is changed from the low compression ratio to the high compression ratio, the oil control valve 45 is switched to the first switching position. At this time, the oil in the control oil passage 46 is introduced into the first hydraulic chamber 31A through the control oil passages 38, 34, 32B, and 32A by the oil pump 44.

  As a result, the operating pin 28 moves to the left in FIGS. 5 and 6 due to the pressure of the oil introduced into the first hydraulic chamber 31A, and the first large end portion 14 moves in the circumferential direction of the crank pin 7B. Rotate along the clockwise direction.

  For this reason, the first large end portion 14 rotates relative to the second large end portion 24 in the clockwise direction by θ2−θ1 and the second large end portion 24 rotates relative to the first large end portion 14. Thus, it rotates relative to the counterclockwise direction by θ2−θ1 (see the connecting rod 6 having a high compression ratio in FIG. 4).

  At this time, the relative position between the piston pin 8 and the crank pin 7B is changed, that is, the effective connecting rod length becomes longer than that in the low compression ratio state. As a result, the volume of the combustion chamber 9 is reduced as compared with the low compression ratio, resulting in a high compression ratio.

  Thus, according to the variable compression ratio mechanism of the present embodiment, the connecting rod 6 is installed in parallel with the same crank pin 7B and the same piston pin 8 and the first connecting rod portion 11 and the second connecting rod. It has a rod part 21.

  The first connecting rod portion 11 includes a first small end portion 12 and a first arm portion 13 connected to the piston pin 8, a first large end portion 14 connected to the crank pin 7B, and a first And a first connecting pin 15 that connects the large end portion 14 to the first arm portion 13.

  The second connecting rod portion 21 includes a second small end portion 22 and a second arm portion 23 connected to the piston pin 8, a second large end portion 24 connected to the crank pin 7B, and a second And a second connecting pin 25 that connects the large end portion 24 to the second arm portion 23.

Furthermore, an operation mechanism 71 is provided that relatively rotates the first large end portion 14 and the second large end portion 24 around the crankpin 7B.
Thereby, the action | operation mechanism 71 can be installed in the 1st big end part 14 and the 2nd big end part 24 which move integrally with the crankpin 7B. Therefore, the operating mechanism 71 is installed in the first small end portion 12, the second small end portion 22, the first arm portion 13, and the second arm portion 23, which are the inertial masses of the connecting rod 6 that reciprocates. Can be made unnecessary, and inertial mass can be reduced.

In addition to this, the relative position between the crank pin 7B and the piston pin 8 is changed by relatively moving the first large end portion 14 and the second large end portion 24 in the circumferential direction of the crank pin 7B. Since the compression ratio can be easily varied, friction loss between the first connecting rod portion 11 and the second connecting rod portion 21 can be reduced when the compression ratio is varied.
As a result, the operability of the variable compression ratio mechanism when varying the compression ratio can be improved.

  Further, according to the variable compression ratio mechanism of the present embodiment, the first small end portion 12 and the first arm portion 13 are in a state where the first large end portion 14 and the second large end portion 24 are relatively rotated. The second small end portion 22 and the second arm portion 23 are installed such that the first connecting pin 15 and the second connecting pin 25 are equidistant from the piston pin 8.

  Further, in a state where the first large end portion 14 and the second large end portion 24 are relatively rotated, the first large end portion 14 and the second large end portion 24 are connected to the first connecting pin 15 and the second large end portion 24, respectively. The two connecting pins 25 are installed at equal intervals with respect to the crank pin 7B.

  Thus, the first connecting rod portion 11 and the second connecting rod portion 21 are always positioned symmetrically with respect to an imaginary line 61 connecting the center axis C1 of the crankpin 7B and the center axis C2 of the piston pin 8. Can be installed. For this reason, the weight distribution between the first connecting rod portion 11 and the second connecting rod portion 21 can be optimized, for example, divided into two equal parts.

  In addition, the first connecting rod portion 11 and the second connecting rod portion 21 can be formed from the same configuration or the same material, and the number of parts of the connecting rod 6 can be reduced.

  Further, according to the variable compression ratio mechanism of the present embodiment, the operating mechanism 71 is provided in the hydraulic chamber 31 provided in the second large end portion 24 and the first large end portion 14, and the hydraulic chamber 31 is An operating pin 28 is provided that is movable within the hydraulic chamber 31 so as to be divided into a first hydraulic chamber 31A and a second hydraulic chamber 31B.

  In this variable compression ratio mechanism, oil is supplied to either the first hydraulic chamber 31A or the second hydraulic chamber 31B, so that the first large end portion 14 and the second large end portion 24 are relative to each other. Rotate.

  As a result, the first large end portion 14 and the second large end portion 24 are moved relative to each other using the hydraulic chamber 31 and the operating pin 28 provided in the first large end portion 14 and the second large end portion 24. By rotating, the compression ratio can be easily varied.

  Furthermore, when the compression force or inertia force due to the combustion pressure acts on the piston 5, the first hydraulic chamber 31A and the second hydraulic chamber 31B are supplied with the first hydraulic pressure without extremely increasing the hydraulic pressure of the oil. The large end portion 14 and the second large end portion 24 can be prevented from moving relative to each other.

  Specifically, in FIG. 11, the compression force F and the inertial force F due to the combustion pressure are distributed to the component forces FA and FB, and the first small end portion 12 and the second small end portion 22 from the piston 5, respectively. It is transmitted to the first connecting pin 15 and the second connecting pin 25 through the first arm portion 13 and the second arm portion 23.

  At this time, the component forces FA and FB acting on the first connecting pin 15 and the second connecting pin 25 are respectively directed to the component force F1 directed to the center axis C1 of the crankpin 7B and the circumferential direction of the crankpin 7B. Distributed to the component force F2. Note that the angle θ at which the virtual line 61 and the component forces FA and FB act is the same angle, and the angle Φ formed by the virtual line 61 and the virtual line 62 is the same angle.

  During the reciprocating motion of the connecting rod 6, the first large end portion 14 and the second large end portion 24 are inclined to θ1 or θ2 with respect to the virtual line 61, so that the component force F2 is a component force It becomes smaller than F1.

Accordingly, the first large end portion 14 and the second large end portion 24 are relatively moved without extremely increasing the hydraulic pressure of the oil supplied to the first hydraulic chamber 31A and the second hydraulic chamber 31B. It is possible to prevent the compression ratio from being changed unintentionally.
Note that the hydraulic chamber 31 may be provided at the first large end portion 14, and the operating pin 28 may be provided at the second large end portion 24.

  Further, according to the variable compression ratio mechanism of the present embodiment, the operation mechanism 71 includes the oil pump 44 and the oil pan 51, the oil pump 44 and the oil pan 51, the first hydraulic chamber 31A, and the second hydraulic chamber 31B. Are connected, and an oil pump 44 supplies oil from the oil pan 51 to the first hydraulic chamber 31A and the second hydraulic chamber 31B, a control oil passage 46, a main oil passage 43, control oil passages 38 and 39, and oil. And passages 32 and 33.

  In addition to this, the operating mechanism 71 is provided in the control oil passages 38, 39, and 46, and oil is supplied from the oil pan 51 to one of the first hydraulic chamber 31A and the second hydraulic chamber 31B by the oil pump 44. Is provided with an oil control valve 45 for switching the oil flow so that the oil is discharged from either one of the first hydraulic chamber 31A and the second hydraulic chamber 31B.

  Thus, the oil control valve 45 causes the oil supply path to the first hydraulic chamber 31A and the second hydraulic chamber 31B, and the oil discharge path from the first hydraulic chamber 31A and the second hydraulic chamber 31B. It can be switched easily. For this reason, the configuration of the oil passage constituting the operating mechanism 71 can be simplified, and the oil passage can be easily formed in the cylinder block 2.

  While embodiments of the invention have been disclosed, it will be apparent to those skilled in the art that changes may be made without departing from the scope of the invention. All such modifications and equivalents are intended to be included in the following claims.

  1 ... Engine (internal combustion engine), 4 ... Cylinder, 5 ... Piston, 6 ... Connecting rod, 7 ... Crankshaft, 7B ... Crank pin, 8 ... Piston pin, DESCRIPTION OF SYMBOLS 11 ... Connecting rod (1st connecting rod part), 12 ... 1st small edge part (1st structural member), 13 ... 1st arm part (1st structural member), 14 ... first large end (second component), 15 ... first connecting pin (second component), 21 ... second connecting rod, 22 ... first 2 small end portions (third constituent member), 23 ... second arm portion (third constituent member), 24 ... second large end portion (fourth constituent member), 25 ... 2nd connection pin (4th component), 28 ... Actuation pin (moving member, actuating mechanism), 31 ... Hydraulic chamber (actuating mechanism), 31A ... Hydraulic chamber (1st hydraulic chamber) ), 31B ... Hydraulic chamber (second hydraulic chamber) , 32, 33 ... Oil passage (oil passage, operation mechanism), 38, 39, 46 ... Control oil passage (oil passage, operation mechanism), 43 ... Main oil passage (oil passage, operation mechanism) ), 44 ... Oil pump (hydraulic power source, operating mechanism), 45 ... Oil control valve (hydraulic control valve, operating mechanism), 51 ... Oil pan (hydraulic power source, operating mechanism), 71 ... Actuation mechanism

Claims (4)

A connecting rod that connects a piston pin of a piston that reciprocates in a cylinder of an internal combustion engine and a crank pin of a crankshaft that performs rotational motion;
A variable compression ratio mechanism that varies a compression ratio by changing a relative position between the piston pin and the crank pin,
The connecting rod has a first connecting rod portion and a second connecting rod portion installed in parallel to the same crank pin and the same piston pin,
The first connecting rod portion includes a first component member and a second component member,
The second connecting rod portion includes a third component member and a fourth component member,
Each of the first component member and the third component member includes a small end portion coupled to the piston pin, and an arm portion extending from the small end portion toward the crank pin.
Each of the second component member and the fourth component member includes at least a large end portion coupled to the crank pin, and a connection pin that pivotally couples at least the large end portion to the arm portion. And
At least the second component member and the fourth component member are provided with an operating mechanism for moving the second component member and the fourth component member relative to each other about the crank pin. Characteristic variable compression ratio mechanism. When the connecting pin of the second component member is a first connecting pin and the connecting pin of the fourth component member is a fourth connecting pin,
In a state where the large end of the first connecting rod portion and the large end of the second connecting rod portion are relatively rotated, the first component member and the second component member are connected to the first coupling member. The pin and the second connecting pin are installed so as to be equidistant from the piston pin,
The third component member and the fourth component member are installed so that the first connection pin and the second connection pin are equidistant from the crank pin. The variable compression ratio mechanism according to claim 1. The operating mechanism is:
A hydraulic chamber provided in any one of the second component member and the fourth component member;
A movable member provided on one of the second component member and the fourth component member and movable in the hydraulic chamber so as to partition the hydraulic chamber into a first hydraulic chamber and a second hydraulic chamber. And
The hydraulic fluid is supplied to either the first hydraulic chamber or the second hydraulic chamber to move the second component member and the fourth component member relative to each other. The variable compression ratio mechanism according to claim 1 or claim 2. The operating mechanism is:
A hydraulic source;
An oil passage that connects the hydraulic source to the first hydraulic chamber and the second hydraulic chamber, and supplies hydraulic oil from the hydraulic source to the first hydraulic chamber and the second hydraulic chamber;
The first hydraulic chamber and the second hydraulic chamber provided in the oil passage when hydraulic oil is supplied from the hydraulic source to either the first hydraulic chamber or the second hydraulic chamber. The variable compression ratio mechanism according to claim 3, further comprising a hydraulic control valve that switches a flow of the hydraulic oil so as to discharge the hydraulic oil from any one of the two.