JP2017129089A - Variable length connecting rod and variable compression ratio internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the lowering of the rigidity of a connecting rod main body accompanied by the formation of an oil passage of a lubricant, in a variable length connecting rod which is changeable in an effective length by turning an eccentric member.SOLUTION: A variable length connecting rod 6 comprises an eccentric member 32 in which a piston pin receiving opening 32d is formed, and a connecting rod main body 31 having a large-diameter end part 31a in which a crank receiving opening 41 for receiving a crank pin 22 is formed, and a small-diameter end part 31b in which an eccentric member receiving opening 42 for receiving the eccentric member is formed. The eccentric member turns between a first position and a second position so as to change a length between a center of the piston pin receiving opening and a center of the crank receiving opening. Only one lubricant hole 311 for making the outside of the connecting rod main body and the eccentric member receiving opening communicate with each other is formed at the small-diameter end part, and penetration paths 321, 322 for making the lubricant hole and the piston pin receiving opening communicate with each other when at least the eccentric member is in the first position or the second position are formed at the eccentric member.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a variable length connecting rod and a variable compression ratio internal combustion engine provided with a variable length connecting rod.

  Conventionally, an internal combustion engine having a variable compression ratio mechanism capable of changing the mechanical compression ratio of the internal combustion engine is known. Various types of such variable compression ratio mechanisms have been proposed, and one of them is one that changes the effective length of a connecting rod used in an internal combustion engine (for example, Patent Document 1). Here, the effective length of the connecting rod means the length between the center of the crank receiving opening for receiving the crank pin and the center of the piston pin receiving opening for receiving the piston pin. Therefore, when the effective length of the connecting rod is increased, the combustion chamber volume when the piston is at the compression top dead center is reduced, and thus the mechanical compression ratio is increased. On the other hand, when the effective length of the connecting rod is shortened, the combustion chamber volume when the piston is at the compression top dead center is increased, and thus the mechanical compression ratio is lowered.

  As a variable-length connecting rod capable of changing the effective length, one having an eccentric member (an eccentric arm or an eccentric sleeve) that is rotatable with respect to the connecting rod body is known at the small-diameter end of the connecting rod body (for example, Patent Document 1). The eccentric member is rotatably received in an eccentric member receiving opening provided at the small diameter end of the connecting rod body. The eccentric member has a piston pin receiving opening for receiving the piston pin, and the piston pin receiving opening is provided eccentrically with respect to the rotational axis of the eccentric member. In such a variable length connecting rod, when the rotational position of the eccentric member is changed, the effective length of the connecting rod can be changed accordingly.

  In such a variable length connecting rod, the piston pin slides against the inner surface of the piston pin receiving opening of the eccentric member by the reciprocating motion of the piston in the cylinder. Further, when the eccentric member is rotated to change the mechanical compression ratio, the eccentric member slides against the inner surface of the eccentric member receiving opening of the connecting rod body. For this reason, it is necessary to supply lubricating oil to these sliding parts in order to suppress wear, seizure, etc. of the piston pin, the eccentric member and the connecting rod body.

  In the variable length connecting rod described in Patent Document 1, two lubricating oil holes are formed in the small diameter end portion and the eccentric member of the connecting rod body. When the eccentric member rotates in one direction, one lubricating oil hole of the small diameter end communicates with one lubricating oil hole of the eccentric member, and when the eccentric member rotates in the other direction, the other of the small diameter end The lubricating oil hole communicates with the other lubricating oil hole of the eccentric member. Accordingly, even when the eccentric member is rotated to change the mechanical compression ratio, the lubricating oil can be supplied to the sliding portion.

Japanese Patent Application Laid-Open No. 2015-152013 Japanese Unexamined Patent Publication No. 7-54997 JP 10-37733 A

  However, if two lubricating oil holes are formed in the small diameter end of the connecting rod body, the strength of the small diameter end is significantly reduced. For this reason, when a force is applied to the small-diameter end by reciprocation of the piston, particularly when a tensile load is applied to the small-diameter end due to the piston rising, the small-diameter end may be damaged.

  Accordingly, in view of the above problems, an object of the present invention is to reduce the strength of the connecting rod body associated with the formation of the oil passage of the lubricating oil in the variable length connecting rod that can change the effective length by rotating the eccentric member. It is to suppress.

  In order to solve the above problems, in the first invention, an eccentric member provided with a piston pin receiving opening for receiving a piston pin, a large diameter end portion provided with a crank receiving opening for receiving a crank pin, A connecting rod body having a small-diameter end provided with an eccentric member receiving opening for receiving the eccentric member, and the eccentric member has a length between the center of the piston pin receiving opening and the center of the crank receiving opening. In the variable-length connecting rod that rotates between the first position and the second position so as to change the position, a lubricating oil hole that communicates the outside of the connecting rod main body and the eccentric member receiving opening to the small diameter end portion. Only one is formed, and the penetrating member communicates with the lubricating oil hole and the piston pin receiving opening when at least the eccentric member is in the first position and the second position. There, characterized in that it is formed, a variable length connecting rod is provided.

  According to a second aspect, in the first aspect, the variable length connecting rod has a stop position of rotation of the eccentric member to one of the third position between the first position and the second position, and the first position. And further comprising a stop device configured to switch between one position and the through-passage when the eccentric member is at least in the first position, the second position and the third position. And the piston pin receiving opening.

  In a third invention, in the first invention, the through passage includes a first through hole that communicates the lubricating oil hole and the piston pin receiving opening when the eccentric member is in the first position; A second through hole that communicates the lubricating oil hole with the piston pin receiving opening when the eccentric member is in the second position.

  According to a fourth aspect, in the second aspect, the through passage includes a first through hole that communicates the lubricating oil hole and the piston pin receiving opening when the eccentric member is in the first position; A second through hole communicating the lubricating oil hole and the piston pin receiving opening when the eccentric member is in the second position; and the lubricating oil hole and the piston when the eccentric member is in the third position. A third through hole communicating with the pin receiving opening.

  According to a fifth invention, in the first or second invention, the through passage extends in a rotation direction of the eccentric member so as to communicate with the lubricating oil hole regardless of a rotation position of the eccentric member. A variable compression ratio internal combustion engine is provided that includes a groove and a through hole that communicates the groove with the piston pin receiving opening.

  According to a sixth aspect of the present invention, there is provided a variable compression ratio internal combustion engine capable of changing a mechanical compression ratio, comprising the variable length connecting rod according to any one of the first to fifth aspects, wherein the piston pin receiving opening is provided by the variable length connecting rod. A variable compression ratio internal combustion engine is provided in which the mechanical compression ratio is changed by changing the length between the center of the crank receiving opening and the center of the crank receiving opening.

  According to the present invention, in the variable-length connecting rod that can change the effective length by rotating the eccentric member, it is possible to suppress a decrease in strength of the connecting rod body that accompanies the formation of the oil passage of the lubricating oil.

FIG. 1 is a schematic side cross-sectional view of a variable compression ratio internal combustion engine according to the first embodiment. FIG. 2 is a perspective view schematically showing the variable length connecting rod according to the first embodiment. FIG. 3 is a side sectional view schematically showing the variable length connecting rod according to the first embodiment. FIG. 4 is a schematic exploded perspective view of the vicinity of the small diameter end of the connecting rod body. FIG. 5 is a side cross-sectional view of the connecting rod in which a region where the flow direction switching mechanism is provided is enlarged. 6A is a cross-sectional view of the connecting rod along the line AA in FIG. 5, and FIG. 6B is a cross-sectional view of the connecting rod along the line BB in FIG. FIG. 7 is a side sectional view schematically showing the variable length connecting rod according to the first embodiment. FIG. 8 is a schematic diagram for explaining the operation of the flow direction switching mechanism when the hydraulic pressure is supplied from the hydraulic supply source to the switching pin. FIG. 9 is a schematic diagram for explaining the operation of the flow direction switching mechanism when no hydraulic pressure is supplied from the hydraulic supply source to the switching pin. FIG. 10 is a perspective view schematically showing a variable length connecting rod according to the second embodiment. FIG. 11 is a side sectional view schematically showing the variable length connecting rod according to the second embodiment. FIG. 12 is a schematic exploded perspective view of the vicinity of the small diameter end of the connecting rod body. FIG. 13 is a side cross-sectional view of the connecting rod in which a region where the flow direction switching mechanism is provided is enlarged. 14A is a cross-sectional view of the connecting rod along the line CC in FIG. 13, and FIG. 14B is a cross-sectional view of the connecting rod along the line DD in FIG. FIG. 15 is a schematic diagram for explaining the operation of the variable length connecting rod when a medium hydraulic pressure is supplied to the switching pin or the like. FIG. 16 is a schematic diagram for explaining the operation of the variable-length connecting rod when high hydraulic pressure is supplied to the switching pin or the like. FIG. 17 is a schematic diagram for explaining the operation of the variable-length connecting rod when low hydraulic pressure is supplied to the switching pin or the like. FIG. 18 is a side cross-sectional view schematically showing the variable length connecting rod according to the second embodiment. FIG. 19 is a side cross-sectional view schematically showing a variable length connecting rod according to the third embodiment. FIG. 20 is a schematic exploded perspective view of the vicinity of the small diameter end of the connecting rod body. FIG. 21 is a side sectional view schematically showing a variable-length connecting rod according to the third embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following description, the same reference numerals are assigned to similar components.

<First embodiment>
First, the variable length connecting rod according to the first embodiment of the present invention will be described with reference to FIGS.

<Variable compression ratio internal combustion engine>
FIG. 1 is a schematic side sectional view of a variable compression ratio internal combustion engine according to a first embodiment of the present invention. Referring to FIG. 1, reference numeral 1 denotes an internal combustion engine. The internal combustion engine 1 includes a crankcase 2, a cylinder block 3, a cylinder head 4, a piston 5, a variable length connecting rod 6, a combustion chamber 7, a spark plug 8 disposed in the center of the top surface of the combustion chamber 7, an intake valve 9, an intake air A camshaft 10, an intake port 11, an exhaust valve 12, an exhaust camshaft 13, and an exhaust port 14 are provided. The cylinder block 3 defines a cylinder 15. The piston 5 slides in the cylinder 15.

  The variable length connecting rod 6 is connected to the piston 5 via the piston pin 21 at the small diameter end portion thereof, and is connected to the crank pin 22 of the crankshaft at the large diameter end portion thereof. As will be described later, the variable length connecting rod 6 can change the distance between the axis of the piston pin 21 and the axis of the crank pin 22, that is, the effective length.

  When the effective length of the variable length connecting rod 6 is increased, the length from the crank pin 22 to the piston pin 21 is increased, so that the combustion chamber 7 when the piston 5 is at the top dead center as shown by the solid line in the figure. The volume of becomes smaller. On the other hand, even if the effective length of the variable-length connecting rod 6 changes, the stroke length that the piston 5 reciprocates in the cylinder does not change. Therefore, at this time, the mechanical compression ratio in the internal combustion engine 1 is increased.

  On the other hand, if the effective length of the variable-length connecting rod 6 is shortened, the length from the crank pin 22 to the piston pin 21 is shortened, so that the combustion when the piston 5 is at the top dead center as shown by the broken line in the figure. The volume in the chamber 7 is increased. However, as described above, the stroke length of the piston 5 is constant. Therefore, at this time, the mechanical compression ratio in the internal combustion engine 1 becomes small.

<Configuration of variable length connecting rod>
FIG. 2 is a perspective view schematically showing the variable length connecting rod 6 according to the first embodiment, and FIG. 3 is a side sectional view schematically showing the variable length connecting rod 6 according to the first embodiment. As shown in FIGS. 2 and 3, the variable length connecting rod 6 includes a connecting rod body 31, an eccentric member 32 rotatably attached to the connecting rod body 31, and a first hydraulic piston mechanism provided in the connecting rod body 31. 33, the second hydraulic piston mechanism 34, the first connecting member 45 that connects the eccentric member 32 and the first hydraulic piston mechanism 33, and the second connecting member 46 that connects the eccentric member 32 and the second hydraulic piston mechanism 34. And a flow direction switching mechanism 35 that switches the flow of oil to the first hydraulic piston mechanism 33 and the second hydraulic piston mechanism 34.

<Connecting rod body>
First, the connecting rod body 31 will be described. The connecting rod body 31 includes a large-diameter end 31a provided with a crank receiving opening 41 for receiving the crankpin 22 of the crankshaft, and a small-diameter end 31b provided with an eccentric member receiving opening 42 for receiving the eccentric member 32. Have. The small diameter end portion 31b is disposed on the piston 5 side and is located on the opposite side of the large diameter end portion 31a. Since the crank receiving opening 41 is larger than the eccentric member receiving opening 42, the end of the connecting rod body 31 on the side where the crank receiving opening 41 is provided is referred to as a large diameter end 31a, and the eccentric member receiving opening 42 is The end of the connecting rod body 31 on the side where it is provided is referred to as a small diameter end 31b.

  Further, in this specification, the center axis of the crank receiving opening 41 (that is, the axis of the crank pin 22 received in the crank receiving opening 41) and the center axis of the eccentric member receiving opening 42 (that is, the eccentric member receiving opening 42). A line X (FIG. 3) extending through the center of the connecting rod body 31 is referred to as an axis X of the connecting rod 6 and the connecting rod body 31.

  The length of the connecting rod 6 in the direction perpendicular to the axis X of the connecting rod 6 and perpendicular to the central axis of the crank receiving opening 41 is referred to as the width of the connecting rod 6. In addition, the length of the connecting rod 6 in the direction parallel to the central axis of the crank receiving opening 41 is referred to as the thickness of the connecting rod 6. As can be seen from FIGS. 2 and 3, the width of the connecting rod main body 31 is the most at the intermediate portion between the large-diameter end portion 31a and the small-diameter end portion 31b except for the region where the piston mechanisms 33 and 34 are provided. thin. Moreover, the width | variety of the large diameter edge part 31a is wider than the width | variety of the small diameter edge part 31b. On the other hand, the thickness of the connecting rod body 31 is substantially constant except for the region where the piston mechanisms 33 and 34 are provided.

<Eccentric member>
Next, the eccentric member 32 will be described. FIG. 4 is a schematic perspective view of the vicinity of the small diameter end portion 31 b of the connecting rod body 31. In FIG. 4, the eccentric member 32 is shown in an exploded state. Referring to FIGS. 2 to 4, the eccentric member 32 includes a cylindrical sleeve 32 a received in an eccentric member receiving opening 42 formed in the connecting rod body 31, and one of the sleeves 32 a in the width direction of the connecting rod body 31. A pair of first arms 32b extending in the direction and a pair of second arms 32c extending from the sleeve 32a in the other direction (generally opposite to the one direction) in the width direction of the connecting rod body 31 are provided. The sleeve 32 a is rotatable within the eccentric member receiving opening 42. For this reason, the eccentric member 32 is attached to the connecting rod body 31 so as to be rotatable in the circumferential direction of the small diameter end portion 31 b at the small diameter end portion 31 b of the connecting rod body 31. The rotation axis of the eccentric member 32 coincides with the central axis of the eccentric member receiving opening 42.

  The sleeve 32a of the eccentric member 32 is provided with a piston pin receiving opening 32d for receiving the piston pin 21. The piston pin receiving opening 32d is formed in a cylindrical shape. The cylindrical piston pin receiving opening 32d is formed so that its axis is parallel to the central axis of the cylindrical outer shape of the sleeve 32a, but not coaxial. Therefore, the axis of the piston pin receiving opening 32d is eccentric from the central axis of the cylindrical outer shape of the sleeve 32a, that is, the rotational axis of the eccentric member 32.

  Thus, in the present embodiment, the central axis of the piston pin receiving opening 32d is eccentric from the rotational axis of the eccentric member 32. For this reason, when the eccentric member 32 rotates, the position of the piston pin receiving opening 32d in the eccentric member receiving opening 42 changes. When the position of the piston pin receiving opening 32d is on the large diameter end portion 31a side in the eccentric member receiving opening 42, the effective length of the connecting rod is shortened. On the contrary, when the position of the piston pin receiving opening 32d in the eccentric member receiving opening 42 is on the side opposite to the large diameter end portion 31a side, that is, on the small diameter end portion 31b side, the effective length of the connecting rod becomes long. Therefore, according to the present embodiment, the effective length of the connecting rod 6 changes by rotating the eccentric member 32. That is, the eccentric member 32 is rotatably attached to the small diameter end portion 31 b of the connecting rod body 31 so as to change the effective length of the connecting rod 6.

<Hydraulic piston mechanism>
Next, the first hydraulic piston mechanism 33 will be described with reference to FIG. The first hydraulic piston mechanism 33 includes a first hydraulic cylinder 33a formed in the connecting rod body 31, a first hydraulic piston 33b that slides within the first hydraulic cylinder 33a, and oil supplied to the first hydraulic cylinder 33a. And a first oil seal 33c. Most or all of the first hydraulic cylinder 33 a is disposed on the first arm 32 b side with respect to the axis X of the connecting rod 6. Further, the first hydraulic cylinder 33a extends while being inclined at a certain angle with respect to the axis X so as to protrude outward in the width direction of the connecting rod body 31 as it approaches the small diameter end portion 31b. Further, the first hydraulic cylinder 33 a communicates with the flow direction switching mechanism 35 via the first piston communication oil passage 51.

  The first hydraulic piston 33 b is connected to the first arm 32 b of the eccentric member 32 by the first connecting member 45. The first hydraulic piston 33b is rotatably connected to the first connecting member 45 by a pin. As shown in FIG. 4, the first arm 32b of the eccentric member 32 is rotatably connected to the first connecting member 45 by a pin at the end opposite to the side connected to the sleeve 32a. Accordingly, the first hydraulic piston 33 b is interlocked with the eccentric member 32. The first oil seal 33c has a ring shape and is attached around the lower end of the first hydraulic piston 33b.

  Next, the second hydraulic piston mechanism 34 will be described. The second hydraulic piston mechanism 34 includes a second hydraulic cylinder 34a formed in the connecting rod body 31, a second hydraulic piston 34b that slides in the second hydraulic cylinder 34a, and oil supplied to the second hydraulic cylinder 34a. A second oil seal 34c. Most or all of the second hydraulic cylinder 34 a is arranged on the second arm 32 c side with respect to the axis X of the connecting rod 6. The second hydraulic cylinder 34a extends while being inclined at a certain angle with respect to the axis X so as to protrude outward in the width direction of the connecting rod body 31 as it approaches the small diameter end portion 31b. Further, the second hydraulic cylinder 34 a communicates with the flow direction switching mechanism 35 via the second piston communication oil passage 52.

  The second hydraulic piston 34 b is connected to the second arm 32 c of the eccentric member 32 by the second connecting member 46. The second hydraulic piston 34b is rotatably connected to the second connecting member 46 by a pin. As shown in FIG. 4, the second arm 32c is rotatably connected to the second connecting member 46 by a pin at the end opposite to the side connected to the sleeve 32a. Therefore, the second hydraulic piston 34 b is interlocked with the eccentric member 32. The second oil seal 34c has a ring shape and is attached around the lower end of the second hydraulic piston 34b.

<Flow direction switching mechanism>
Next, the configuration of the flow direction switching mechanism 35 will be described with reference to FIGS. 5 and 6. FIG. 5 is a side sectional view of the connecting rod 6 in which a region where the flow direction switching mechanism 35 is provided is enlarged. 6A is a cross-sectional view of the connecting rod 6 along the line AA in FIG. 5, and FIG. 6B is a cross-sectional view of the connecting rod 6 along the line BB in FIG. The flow direction switching mechanism 35 is in a first state in which the flow of oil from the first hydraulic cylinder 33a to the second hydraulic cylinder 34a is prohibited and the flow of oil from the second hydraulic cylinder 34a to the first hydraulic cylinder 33a is permitted. , And the second state in which the flow of oil from the first hydraulic cylinder 33a to the second hydraulic cylinder 34a is permitted and the flow of oil from the second hydraulic cylinder 34a to the first hydraulic cylinder 33a is prohibited.

  As shown in FIG. 5, the flow direction switching mechanism 35 includes two switching pins 61 and 62 and one check valve 63. The two switching pins 61 and 62 and the check valve 63 are disposed between the first hydraulic cylinder 33 a and the second hydraulic cylinder 34 a and the crank receiving opening 41 in the axis X direction of the connecting rod body 31. The check valve 63 is disposed closer to the crank receiving opening 41 than the two switching pins 61 and 62 in the direction of the axis X of the connecting rod body 31.

  Further, the two switching pins 61 and 62 are provided on both sides with respect to the axis X of the connecting rod body 31 and the check valve 63 is provided on the axis X. Thereby, it can suppress that the weight balance of the right and left of the connecting rod main body 31 falls by providing the switching pins 61 and 62 and the check valve 63 in the connecting rod main body 31.

  The two switching pins 61 and 62 are housed in cylindrical pin housing spaces 64 and 65, respectively. In the present embodiment, the pin accommodating spaces 64 and 65 are formed such that the axis thereof extends in parallel with the central axis of the crank receiving opening 41. The switching pins 61 and 62 can slide in the pin accommodating spaces 64 and 65 in the direction in which the pin accommodating spaces 64 and 65 extend. That is, the switching pins 61 and 62 are disposed in the connecting rod body 31 so that the operating direction thereof is parallel to the central axis of the crank receiving opening 41.

  Further, the first pin accommodating space 64 that accommodates the first switching pin 61 out of the two pin accommodating spaces 64 and 65 is open with respect to one side surface of the connecting rod body 31 as shown in FIG. And a pin receiving hole which is closed with respect to the other side surface of the connecting rod body 31. In addition, the second pin accommodating space 65 that accommodates the second switching pin 62 out of the two pin accommodating spaces 64 and 65 corresponds to the other side surface of the connecting rod body 31 as shown in FIG. And is formed as a pin receiving hole that is open and closed with respect to the one side surface.

  The first switching pin 61 has two circumferential grooves 61a and 61b extending in the circumferential direction. The circumferential grooves 61 a and 61 b are communicated with each other by a communication path 61 c formed in the first switching pin 61. The first pin accommodating space 64 accommodates a first urging spring 67 and a first support member 76 that supports the first urging spring 67. The first support member 76 is a snap ring such as a C ring or an E ring, and is disposed in a circumferential groove formed in the first pin accommodation space 64. The first switching pin 61 is urged by a first urging spring 67 in a direction parallel to the central axis of the crank receiving opening 41. In particular, in the example shown in FIG. 6A, the first switching pin 61 is urged toward the closed end of the first pin accommodating space 64.

  Similarly, the second switching pin 62 also has two circumferential grooves 62a and 62b extending in the circumferential direction. The circumferential grooves 62 a and 62 b are communicated with each other by a communication path 62 c formed in the second switching pin 62. The second pin accommodating space 65 accommodates a second urging spring 68 and a second support member 77 that supports the second urging spring 68. The second support member 77 is a snap ring such as a C ring or an E ring, and is disposed in a circumferential groove formed in the second pin housing space 65. The second switching pin 62 is biased by a second biasing spring 68 in a direction parallel to the central axis of the crank receiving opening 41. In particular, in the example illustrated in FIG. 6A, the second switching pin 62 is urged toward the closed end of the second pin housing space 65. As a result, the second switching pin 62 is biased in the opposite direction to the first switching pin 61.

  In addition, the first switching pin 61 and the second switching pin 62 are disposed in opposite directions in a direction parallel to the central axis of the crank receiving opening 41. In addition, the second switching pin 62 is urged in the opposite direction to the first switching pin 61. For this reason, in this embodiment, when hydraulic pressure is supplied to the first switching pin and the second switching pin 62, the operating directions of the first switching pin 61 and the second switching pin 62 are opposite to each other.

  The check valve 63 is accommodated in a cylindrical check valve accommodation space 66. In the present embodiment, the check valve accommodating space 66 is also formed so as to extend in parallel with the central axis of the crank receiving opening 41. The check valve 63 can slide in the direction in which the check valve accommodation space 66 extends in the check valve accommodation space 66. Therefore, the check valve 63 is disposed in the connecting rod body 31 so that the operating direction thereof is parallel to the central axis of the crank receiving opening 41. The check valve accommodation space 66 is formed as a check valve accommodation hole that is open to one side surface of the connecting rod body 31 and is closed to the other side surface of the connecting rod body 31. The check valve 63 permits the flow from the primary side (upper side in FIG. 6B) to the secondary side (lower side in FIG. 6B) and prohibits the flow from the secondary side to the primary side. Configured as follows.

  The first pin accommodating space 64 that accommodates the first switching pin 61 is communicated with the first hydraulic cylinder 33 a via the first piston communication oil passage 51. As shown in FIG. 6A, the first piston communication oil passage 51 is communicated with the first pin housing space 64 in the vicinity of the center of the connecting rod body 31 in the thickness direction. The second pin housing space 65 that houses the second switching pin 62 is communicated with the second hydraulic cylinder 34 a via the second piston communication oil passage 52. As shown in FIG. 6A, the second piston communication oil passage 52 is also communicated with the second pin housing space 65 in the vicinity of the center of the connecting rod body 31 in the thickness direction.

  The first piston communication oil passage 51 and the second piston communication oil passage 52 are formed by cutting from the crank receiving opening 41 with a drill or the like. Therefore, on the crank receiving opening 41 side of the first piston communication oil passage 51 and the second piston communication oil passage 52, the first extension oil passage 51a and the second extension oil passage 52a that are coaxial with the piston communication oil passages 51, 52 are provided. Is formed. In other words, the first piston communication oil passage 51 and the second piston communication oil passage 52 are formed such that the crank receiving opening 41 is positioned on the extension line. The first extension oil passage 51a and the second extension oil passage 52a are closed by a bearing metal 71 provided in the crank receiving opening 41, for example.

  The first pin accommodation space 64 that accommodates the first switching pin 61 is communicated with the check valve accommodation space 66 via the two space communication oil passages 53 and 54. Among these, as shown in FIG. 6, one of the first space communication oil passages 53 is the first on the side surface side (lower side in FIG. 6B) from the center in the thickness direction of the connecting rod body 31. The pin housing space 64 and the check valve housing space 66 communicate with the secondary side. The other second space communication oil passage 54 has a first pin housing space 64 and a check valve housing space 66 on the other side surface side (upper side in FIG. 6B) than the center in the thickness direction of the connecting rod body 31. To the primary side. In addition, the first space communication oil passage 53 and the second space communication oil passage 54 are configured such that the distance between the first space communication oil passage 53 and the first piston communication oil passage 51 in the connecting rod main body thickness direction and the second space communication oil passage 53 are the same. The distance in the connecting rod body thickness direction between the oil passage 54 and the first piston communication oil path 51 is arranged to be equal to the distance in the connecting rod body thickness direction between the circumferential grooves 61a and 61b. As a result, the oil passage through which the first piston communication oil passage 51 communicates with the first space communication oil passage 53 and the second space communication oil passage 54 by sliding of the first switching pin 61 in the first pin housing space 64. Can be switched between.

  The second pin housing space 65 that houses the second switching pin 62 is communicated with the check valve housing space 66 through the two space communication oil passages 55 and 56. Among these, as shown in FIG. 6, one third space communication oil passage 55 is second on the side surface side (lower side in FIG. 6B) from the center in the thickness direction of the connecting rod body 31. The pin housing space 65 and the check valve housing space 66 are communicated with the secondary side. The other fourth space communication oil passage 56 has a second pin accommodation space 65 and a check valve accommodation space 66 on the other side surface side (upper side in FIG. 6B) than the center in the thickness direction of the connecting rod body 31. To the primary side. In addition, the third space communication oil passage 55 and the fourth space communication oil passage 56 are configured such that the distance in the connecting rod body thickness direction between the third space communication oil passage 55 and the second piston communication oil passage 52 and the fourth space communication The distance in the connecting rod body thickness direction between the oil passage 56 and the second piston communication oil path 52 is arranged to be equal to the distance in the connecting rod body thickness direction between the circumferential grooves 62a and 62b. As a result, the oil passage in which the second piston communication oil passage 52 communicates with the third space communication oil passage 55 and the fourth space communication oil passage 56 by the sliding of the second switching pin 62 in the second pin housing space 65. Can be switched between.

  These space communication oil passages 53 to 56 are formed by cutting from the crank receiving opening 41 with a drill or the like. Accordingly, extended oil passages 53a to 56a coaxial with the space communication oil passages 53 to 56 are formed on the side of the crank receiving opening 41 of the space communication oil passages 53 to 56. In other words, each of the space communication oil passages 53 to 56 is formed such that the crank receiving opening 41 is located on the extension line. These extension oil passages 53a to 56a are closed by a bearing metal 71, for example.

  As described above, the extension oil passages 51 a to 56 a are all closed by the bearing metal 71. For this reason, the extension oil passages 51a to 56a can be closed by only assembling the connecting rod 6 to the crank pin 22 using the bearing metal 71 without any additional processing for closing the extension oil passages 51a to 56a.

  In the connecting rod body 31, a first control oil passage 57 for supplying hydraulic pressure to the first switching pin 61 and a second control oil passage 58 for supplying hydraulic pressure to the second switching pin 62 are provided. Is formed. The first control oil passage 57 is communicated with the first pin housing space 64 at the end opposite to the end where the first biasing spring 67 is provided. The second control oil passage 58 is communicated with the second pin housing space 65 at the end opposite to the end where the second urging spring 68 is provided. These control oil passages 57, 58 are formed so as to communicate with the crank receiving opening 41, and an oil supply device outside the connecting rod 6 through an oil passage (not shown) formed in the crank pin 22. Communicated with

  Therefore, when the hydraulic pressure is not supplied from the oil supply device, the first switching pin 61 and the second switching pin 62 are biased by the first biasing spring 67 and the second biasing spring 68, respectively, and FIG. As shown in FIG. 5B, the pin housing spaces 64 and 65 are located on the closed end side. On the other hand, when a hydraulic pressure higher than a predetermined pressure is supplied from the oil supply device, the first switching pin 61 and the second switching pin 62 resist the biasing by the first biasing spring 67 and the second biasing spring 68, respectively. And are located on the open end sides in the pin receiving spaces 64 and 65, respectively.

  Further, a refilling oil passage 59 is formed in the connecting rod body 31 for replenishing oil to the primary side of the check valve 63 in the check valve housing space 66 in which the check valve 63 is housed. One end of the refilling oil passage 59 is communicated with the check valve accommodating space 66 on the primary side of the check valve 63. The other end of the refilling oil passage 59 is communicated with the crank receiving opening 41. Further, a through hole 71 a is formed in the bearing metal 71 in accordance with the supplementary oil passage 59. The replenishment oil passage 59 is communicated with the oil supply device through the through hole 71a. Therefore, the primary side of the check valve 63 communicates with the oil supply device at all times or regularly according to the rotation of the crankshaft by the supplementary oil passage 59.

<Operation of variable length connecting rod>
Next, the operation of the variable length connecting rod 6 will be described with reference to FIGS. FIG. 7A shows a state where oil is supplied into the first hydraulic cylinder 33 a of the first hydraulic piston mechanism 33 and no oil is supplied into the second hydraulic cylinder 34 a of the second hydraulic piston mechanism 34. ing. On the other hand, FIG. 7B shows that no oil is supplied into the first hydraulic cylinder 33 a of the first hydraulic piston mechanism 33 and no oil is supplied into the second hydraulic cylinder 34 a of the second hydraulic piston mechanism 34. It shows the state being done. FIG. 8 is a schematic diagram for explaining the operation of the flow direction switching mechanism 35 when a hydraulic pressure equal to or higher than a predetermined pressure is supplied from the oil supply device 75 to the switching pins 61 and 62. FIG. 8 is a schematic diagram for explaining the operation of the flow direction switching mechanism 35 when no hydraulic pressure is supplied from the oil supply device 75 to the switching pins 61 and 62.

  The variable length connecting rod 6 further includes an oil supply device 75 and an electronic control unit (ECU) 40. The oil supply device 75 supplies hydraulic pressure to the first switching pin 61 via the first control oil passage 57 and supplies hydraulic pressure to the second switching pin 62 via the second control oil passage 58. The oil supply device 75 is disposed outside the connecting rod body 31 and is controlled by the ECU 40. Therefore, the ECU 40 can control the hydraulic pressure supplied to the first switching pin 61 and the second switching pin 62 by the oil supply device 75. 8 and 9, the oil supply device 75 that supplies hydraulic pressure to the first switching pin 61 and the second switching pin 62 and the oil supply device 75 that supplies oil to the supplementary oil passage 59 are depicted separately. However, in this embodiment, hydraulic pressure is supplied from the same oil supply device.

  As shown in FIG. 8, when the hydraulic pressure higher than the predetermined pressure is supplied from the oil supply device 75, the switching pins 61 and 62 move against the biasing by the biasing springs 67 and 68, respectively. Located in one position. As a result, the first piston communication oil passage 51 and the first space communication oil passage 53 are communicated by the communication passage 61 c of the first switching pin 61, and the second piston communication oil passage is communicated by the communication passage 62 c of the second switching pin 62. 52 and the fourth space communication oil passage 56 are communicated with each other. Accordingly, the first hydraulic cylinder 33 a is connected to the secondary side of the check valve 63, and the second hydraulic cylinder 34 a is connected to the primary side of the check valve 63.

  Here, the check valve 63 is configured such that the first space communication oil path 53 and the third space communication oil path 55 communicate with each other from the primary side where the second space communication oil path 54 and the fourth space communication oil path 56 communicate with each other. It is configured to allow oil flow to the side but not vice versa. Therefore, in the state shown in FIG. 8, oil flows from the fourth space communication oil path 56 to the first space communication oil path 53, but vice versa.

  As a result, in the state shown in FIG. 8, the oil in the second hydraulic cylinder 34a flows into the second piston communication oil path 52, the fourth space communication oil path 56, the first space communication oil path 53, and the first piston communication oil. The oil can be supplied to the first hydraulic cylinder 33a through the oil passage in the order of the passage 51. However, the oil in the first hydraulic cylinder 33a cannot be supplied to the second hydraulic cylinder 34a. Therefore, when the hydraulic pressure exceeding the predetermined pressure is supplied from the oil supply device 75, the flow direction switching mechanism 35 prohibits the flow of oil from the first hydraulic cylinder 33a to the second hydraulic cylinder 34a and the second hydraulic cylinder. It can be said that it is in the 1st state which permits the flow of oil from 34a to the 1st hydraulic cylinder 33a.

  At this time, as shown in FIG. 7A, oil is supplied to the first hydraulic cylinder 33a, and the oil is discharged from the second hydraulic cylinder 34a. For this reason, the first hydraulic piston 33b rises and the second hydraulic piston 34b falls. As a result, in the example shown in FIG. 7A, the eccentric member 32 connected to the first hydraulic piston 33b and the second hydraulic piston 34b is rotated to the first position in the direction of the arrow in the figure. As a result, the position of the piston pin receiving opening 32d rises. Therefore, the length between the center of the crank receiving opening 41 and the center of the piston pin receiving opening 32d, that is, the effective length of the connecting rod 6 is increased to L1 in the figure. That is, when the flow direction switching mechanism 35 is set to the first state, the effective length of the connecting rod 6 is increased.

  On the other hand, as shown in FIG. 9, when the hydraulic pressure is not supplied from the oil supply device 75, the switching pins 61 and 62 are located at the second positions urged by the urging springs 67 and 68, respectively. As a result, the first piston communication oil passage 51 and the second space communication oil passage 54 communicating with the first hydraulic piston mechanism 33 are communicated with each other by the communication passage 61 c of the first switching pin 61. In addition, the second piston communication oil passage 52 and the third space communication oil passage 55 communicated with the second hydraulic piston mechanism 34 are communicated by the communication passage 62 c of the second switching pin 62. Therefore, the first hydraulic cylinder 33 a is connected to the primary side of the check valve 63, and the second hydraulic cylinder 34 a is connected to the secondary side of the check valve 63.

  In the state shown in FIG. 9 due to the action of the check valve 63 described above, the oil in the first hydraulic cylinder 33a flows into the first piston communication oil passage 51, the second space communication oil passage 54, and the third space communication oil passage. 55 and the second piston communication oil passage 52 can be supplied to the second hydraulic cylinder 34a through the oil passage. However, the oil in the second hydraulic cylinder 34a cannot be supplied to the first hydraulic cylinder 33a. Therefore, when the hydraulic pressure is not supplied from the oil supply device 75, the flow direction switching mechanism 35 permits the flow of oil from the first hydraulic cylinder 33a to the second hydraulic cylinder 34a and from the second hydraulic cylinder 34a to the first. It can be said that it is in the 2nd state which prohibits the flow of the oil to the hydraulic cylinder 33a.

  At this time, as shown in FIG. 7B, oil is supplied to the second hydraulic cylinder 34a, and the oil is discharged from the first hydraulic cylinder 33a. For this reason, the second hydraulic piston 34b rises and the first hydraulic piston 33b falls. As a result, in the example shown in FIG. 7B, the eccentric member 32 is rotated to the second position in the direction of the arrow in the figure (the direction opposite to the arrow in FIG. 7A). As a result, the position of the piston pin receiving opening 32d is lowered. Therefore, the length between the center of the crank receiving opening 41 and the center of the piston pin receiving opening 32d, that is, the effective length of the connecting rod 6 is L2 shorter than L1 in the drawing. That is, when the flow direction switching mechanism 35 is set to the second state, the effective length of the connecting rod 6 is shortened.

  Therefore, in this embodiment, the eccentric member 32 rotates between the first position and the second position so as to change the effective length of the connecting rod 6. For this reason, the effective length of the connecting rod 6 is increased by switching the flow direction switching mechanism 35 between the first state and the second state and rotating the eccentric member 32 between the first position and the second position. It can be switched between L1 and L2. As a result, in the internal combustion engine 1 provided with the connecting rod 6, the mechanical compression ratio can be changed.

<Supply of lubricating oil>
By the way, in the connecting rod 6, the piston pin 21 slides with respect to the inner surface of the piston pin receiving opening 32 d of the eccentric member 32 by the reciprocating motion of the piston 5 in the cylinder 15. Further, when the eccentric member 32 is rotated to change the mechanical compression ratio of the internal combustion engine 1, the eccentric member 32 slides against the inner surface of the eccentric member receiving opening 42 of the connecting rod body 31. For this reason, it is necessary to supply lubricating oil to these sliding parts in order to suppress wear, seizure, and the like of the piston pin 21, the eccentric member 32, and the connecting rod body 31.

  Therefore, in the present embodiment, the small diameter end portion 31b of the connecting rod body 31 is formed with a lubricating oil hole 311 that allows the outside of the connecting rod body 31 to communicate with the eccentric member receiving opening 42. The lubricating oil hole 311 extends in the radial direction of the small diameter end portion 31b. The eccentric member 32 is formed with a through passage that allows the lubricating oil hole 311 and the piston pin receiving opening 32d to communicate with each other when at least the eccentric member 32 is in the first position and the second position.

  In the present embodiment, the through path includes a first through hole 321 and a second through hole 322. The first through hole 321 and the second through hole 322 extend in the radial direction of the sleeve 32a of the eccentric member 32, and pass through the sleeve 32a between the outer peripheral surface of the sleeve 32a and the inner surface of the piston pin receiving opening 32d. To do. The first through hole 321 and the second through hole 322 are separated from each other in the circumferential direction of the sleeve 32a. When the eccentric member 32 is in the first position, the first through hole 321 is formed so that the circumferential position of the lubricating oil hole 311 of the small-diameter end portion 31b coincides. The second through hole 322 is formed so that the position in the circumferential direction coincides with the lubricating oil hole 311 of the small diameter end portion 31b when the eccentric member 32 is in the second position. For this reason, the circumferential distance between the first through hole 321 and the second through hole 322 is the rotation distance of the sleeve 32a when the eccentric member 32 is rotated between the first position and the second position. be equivalent to.

  As can be seen from FIG. 7A, the first through hole 321 allows the lubricating oil hole 311 and the piston pin receiving opening 32d to communicate with each other when the eccentric member 32 is in the first position. As can be seen from FIG. 7B, the second through hole 322 allows the lubricating oil hole 311 and the piston pin receiving opening 32d to communicate with each other when the eccentric member 32 is in the second position.

  Lubricating oil is supplied to the sliding portions of the piston pin 21, the eccentric member 32 and the connecting rod body 31 by the oil jet 16. As shown in FIG. 1, the oil jet 16 is attached to the cylinder block 3. The oil jet 16 injects lubricating oil toward the inside of the piston 5. The lubricating oil adhering to the inner surface of the piston 5 falls toward the small-diameter end portion 31b due to an inertial force or the like due to the reciprocating motion of the piston 5. As a result, part of the lubricating oil adhering to the inner surface of the piston 5 is supplied into the connecting rod body 31 through the lubricating oil hole 311 of the small diameter end portion 31b.

  The lubricating oil flows into the eccentric member receiving opening 42 through the lubricating oil hole 311 and is supplied between the small diameter end portion 31 b and the eccentric member 32. Further, when the eccentric member 32 is in the first position, the lubricating oil flows into the piston pin receiving opening 32 d through the lubricating oil hole 311 and the first through hole 321, and between the eccentric member 32 and the piston pin 21. Supplied. Further, when the eccentric member 32 is in the second position, the lubricating oil flows into the piston pin receiving opening 32d through the lubricating oil hole 311 and the second through hole 322, and between the eccentric member 32 and the piston pin 21. Supplied.

  Therefore, in this embodiment, even when the rotational position of the eccentric member 32 is switched between the first position and the second position in order to change the mechanical compression ratio, the lubricating oil is supplied to the sliding portion. be able to. For this reason, abrasion, seizure, etc. of the piston pin 21, the eccentric member 32, and the connecting rod main body 31 can be suppressed. In the present embodiment, only one lubricating oil hole 311 is formed in the small diameter end portion 31b. For this reason, the fall of the intensity | strength of the connecting rod main body 31 accompanying formation of the oil path of lubricating oil can be suppressed.

<Second embodiment>
Next, a variable length connecting rod 6 ′ according to a second embodiment of the present invention will be described with reference to FIGS. The configuration and operation of the variable length connecting rod 6 ′ according to the second embodiment are basically the same as the configuration and operation of the variable length connecting rod 6 according to the first embodiment, except for the points described below.

<Configuration of variable length connecting rod>
FIG. 10 is a perspective view schematically showing a variable length connecting rod 6 ′ according to the second embodiment. FIG. 11 is a side sectional view schematically showing the variable length connecting rod 6 ′ according to the second embodiment. As shown in FIGS. 10 and 11, the variable length connecting rod 6 ′ includes a connecting rod body 31, an eccentric member 32 rotatably attached to the connecting rod body 31, and a hydraulic piston mechanism 33 provided on the connecting rod body 31. A connecting member 45 that connects the eccentric member 32 and the hydraulic piston mechanism 33, and a flow direction switching mechanism 35 that switches the flow of oil to the hydraulic piston mechanism 33. In the second embodiment, unlike the first embodiment, the number of hydraulic piston mechanisms and connecting members is one. The variable length connecting rod 6 ′ further includes a stop device 36 that switches the stop position of the eccentric member 32 to rotate in one direction in two stages.

<Eccentric member>
FIG. 12 is a schematic exploded perspective view of the vicinity of the small diameter end portion 31 b of the connecting rod body 31. The eccentric member 32 of the variable length connecting rod 6 ′ further includes a rotation restricting portion 32e. The rotation restricting portion 32e is integral with one second arm 32c. The rotation restricting portion 32e may be integrated with the other second arm 32c. When the hydraulic oil is supplied to the hydraulic cylinder 33a and the eccentric member 32 is rotated to one side, the rotation restricting portion 32e restricts the rotation of the eccentric member 32 by coming into contact with the stop device 36.

<Hydraulic piston mechanism>
As shown in FIG. 11, the hydraulic piston mechanism 33 seals the hydraulic cylinder 33a formed in the connecting rod body 31, the hydraulic piston 33b sliding in the hydraulic cylinder 33a, and the oil supplied into the hydraulic cylinder 33a. And an oil seal 33c. Most or all of the hydraulic cylinder 33 a is arranged on the first arm 32 b side with respect to the axis X of the connecting rod 6. Further, the hydraulic cylinder 33a extends while being inclined at a certain angle with respect to the axis X so as to protrude outward in the width direction of the connecting rod body 31 as it approaches the small diameter end portion 31b. Further, the hydraulic cylinder 33 a communicates with the flow direction switching mechanism 35 via the piston communication oil passage 51.

  The hydraulic piston 33 b is connected to the first arm 32 b of the eccentric member 32 by the connecting member 45. The hydraulic piston 33b is rotatably connected to the connecting member 45 by a pin. As shown in FIG. 12, the first arm 32b is rotatably connected to the connecting member 45 by a pin at the end opposite to the side connected to the sleeve 32a. Accordingly, the hydraulic piston 33 b is interlocked with the eccentric member 32. The oil seal 33c has a ring shape and is attached around the lower end of the hydraulic piston 33b.

<Flow direction switching mechanism>
Next, the configuration of the flow direction switching mechanism 35 will be described with reference to FIGS. 13 and 14. FIG. 13 is a side cross-sectional view of the connecting rod 6 ′ in which a region where the flow direction switching mechanism 35 is provided is enlarged. 14A is a cross-sectional view of the connecting rod 6 ′ along the line CC in FIG. 13, and FIG. 14B is a cross-sectional view of the connecting rod 6 ′ along the line DD in FIG. is there. The flow direction switching mechanism 35 permits supplying hydraulic oil to the hydraulic cylinder 33a and prohibits discharging hydraulic oil from the hydraulic cylinder 33a, and supplying hydraulic oil to the hydraulic cylinder 33a. It is switched between a second state that prohibits and permits the hydraulic oil to be discharged from the hydraulic cylinder 33a.

  As shown in FIG. 13, the flow direction switching mechanism 35 includes two switching pins 61 and 62 and one check valve 63. The two switching pins 61 and 62 are housed in cylindrical pin housing spaces 64 and 65, respectively. In the present embodiment, the pin accommodating spaces 64 and 65 are formed such that the axis thereof extends in parallel with the central axis of the crank receiving opening 41. The switching pins 61 and 62 can slide in the pin accommodating spaces 64 and 65 in the direction in which the pin accommodating spaces 64 and 65 extend. That is, the switching pins 61 and 62 are disposed in the connecting rod body 31 so that the operating direction thereof is parallel to the central axis of the crank receiving opening 41.

  Further, the first pin accommodating space 64 that accommodates the first switching pin 61 out of the two pin accommodating spaces 64 and 65 is open with respect to one side surface of the connecting rod body 31 as shown in FIG. And a pin receiving hole which is closed with respect to the other side surface of the connecting rod body 31. In addition, the second pin accommodating space 65 that accommodates the second switching pin 62 out of the two pin accommodating spaces 64 and 65 corresponds to the other side surface of the connecting rod body 31 as shown in FIG. And is formed as a pin receiving hole that is open and closed with respect to the one side surface.

  The first switching pin 61 has two circumferential grooves 61a and 61b extending in the circumferential direction. The circumferential grooves 61 a and 61 b are communicated with each other by a communication path 61 c formed in the first switching pin 61. The first pin accommodating space 64 accommodates a first urging spring 67 and a first support member 76 that supports the first urging spring 67. The first support member 76 is a snap ring such as a C ring or an E ring, and is disposed in a circumferential groove formed in the first pin accommodation space 64. The first switching pin 61 is urged by a first urging spring 67 in a direction parallel to the central axis of the crank receiving opening 41. In particular, in the example shown in FIG. 14A, the first switching pin 61 is urged toward the closed end of the first pin accommodating space 64.

  Similarly, the second switching pin 62 also has two circumferential grooves 62a and 62b extending in the circumferential direction. One circumferential groove 62b is connected to one end of the second switching pin 62 (the end on the side where the second biasing spring 68 is not provided) by a communication path 62c formed in the second switching pin 62. You can communicate. The second pin accommodating space 65 accommodates a second urging spring 68 and a second support member 77 that supports the second urging spring 68. The second support member 77 is a snap ring such as a C ring or an E ring, and is disposed in a circumferential groove formed in the second pin housing space 65. The second switching pin 62 is biased by a second biasing spring 68 in a direction parallel to the central axis of the crank receiving opening 41. In particular, in the example shown in FIG. 14A, the second switching pin 62 is urged toward the closed end of the second pin accommodating space 65. As a result, the second switching pin 62 is biased in the opposite direction to the first switching pin 61.

  In addition, the first switching pin 61 and the second switching pin 62 are disposed in opposite directions in a direction parallel to the central axis of the crank receiving opening 41. In addition, the second switching pin 62 is urged in the opposite direction to the first switching pin 61. For this reason, in this embodiment, when hydraulic pressure is supplied to the first switching pin and the second switching pin 62, the operating directions of the first switching pin 61 and the second switching pin 62 are opposite to each other.

  The check valve 63 is accommodated in a cylindrical check valve accommodation space 66. In the present embodiment, the check valve accommodating space 66 is also formed so as to extend in parallel with the central axis of the crank receiving opening 41. The check valve 63 can slide in the direction in which the check valve accommodation space 66 extends in the check valve accommodation space 66. Therefore, the check valve 63 is disposed in the connecting rod body 31 so that the operating direction thereof is parallel to the central axis of the crank receiving opening 41. The check valve accommodation space 66 is formed as a check valve accommodation hole that is open to one side surface of the connecting rod body 31 and is closed to the other side surface of the connecting rod body 31. The check valve 63 permits the flow from the primary side (upper side in FIG. 14B) to the secondary side (lower side in FIG. 14B) and prohibits the flow from the secondary side to the primary side. Configured as follows.

  The first pin accommodation space 64 that accommodates the first switching pin 61 is communicated with the check valve accommodation space 66 via the two space communication oil passages 53 and 54. Of these, as shown in FIG. 14, one first space communication oil passage 53 has a first pin housing space on one side surface side (lower side in FIG. 14) from the center in the thickness direction of the connecting rod body 31. 64 and the secondary side of the check valve accommodating space 66 are communicated with each other. The other second space communication oil passage 54 is the primary side of the first pin accommodation space 64 and the check valve accommodation space 66 on the other side surface side (upper side in FIG. 14) than the center in the thickness direction of the connecting rod body 31. To communicate with.

  Further, the first pin housing space 64 is communicated with the hydraulic cylinder 33 a via the piston communication oil passage 51. As shown in FIG. 14A, the piston communication oil passage 51 is communicated with the first pin housing space 64 in the vicinity of the center of the connecting rod body 31 in the thickness direction. In addition, the piston communication oil passage 51 has an interval in the connecting rod body thickness direction between the first space communication oil passage 53 and the piston communication oil passage 51 and between the second space communication oil passage 54 and the piston communication oil passage 51. The connecting rod body in the thickness direction is disposed so as to be equal to the connecting rod body thickness direction spacing between the circumferential grooves 61a and 61b. As a result, the oil passage through which the piston communication oil passage 51 communicates is formed between the first space communication oil passage 53 and the second space communication oil passage 54 by the sliding of the first switching pin 61 in the first pin housing space 64. Can be switched between.

  The second pin housing space 65 that houses the second switching pin 62 is communicated with the check valve housing space 66 through the two space communication oil passages 55 and 56. Of these, as shown in FIG. 14, one third space communication oil passage 55 is a second pin housing space on one side surface side (lower side in FIG. 14) from the center in the thickness direction of the connecting rod body 31. 65 and the secondary side of the check valve accommodating space 66 are communicated with each other. The other fourth space communication oil passage 56 is the primary side of the second pin accommodation space 65 and the check valve accommodation space 66 on the other side surface side (upper side in FIG. 14) than the center in the thickness direction of the connecting rod body 31. To communicate with.

  Further, a drain oil passage 60 that communicates with the outside of the connecting rod body 31 is communicated with the second pin housing space 65. As shown in FIG. 14A, the discharge oil passage 60 is disposed at the same position as the third space communication oil passage 55 in the axial direction of the second pin housing space 65. That is, the drain oil passage 60 is configured to communicate with the circumferential groove 62 a at the same time when the circumferential groove 62 a of the second switching pin 62 communicates with the third space communication oil passage 55.

  The oil passages 51 and 53 to 56 described above are formed by cutting the crank receiving opening 41 with a drill or the like. Accordingly, extended oil passages 51 a and 53 a to 56 a coaxial with these oil passages 51, 53 to 56 are formed on the side of the crank receiving opening 41 of these oil passages 51, 53 to 56. In other words, each of the oil passages 51, 53 to 56 is formed such that the crank receiving opening 41 is located on the extension line thereof. These extended oil passages 51 a and 53 a to 56 a are closed by a bearing metal 71, for example. Further, the drain oil passage 60 is formed by cutting with a drill or the like from the outside of the connecting rod main body 31.

  In the connecting rod body 31, a first control oil passage 57 for supplying hydraulic pressure to the first switching pin 61 and a second control oil passage 58 for supplying hydraulic pressure to the second switching pin 62 are provided. Is formed. The first control oil passage 57 is communicated with the first pin housing space 64 at the end opposite to the end where the first biasing spring 67 is provided. The second control oil passage 58 is communicated with the second pin housing space 65 at the end opposite to the end where the second urging spring 68 is provided. These control oil passages 57, 58 are formed so as to communicate with the crank receiving opening 41, and an oil supply device outside the connecting rod 6 through an oil passage (not shown) formed in the crank pin 22. Communicated with

<Stop device>
Next, the stop device 36 will be described. The stop device 36 is configured to switch the stop position of the rotation of the eccentric member 32 to one side (clockwise rotation in FIG. 11) in two stages by the hydraulic pressure supplied from the outside of the connecting rod body 31.

  The stop device 36 includes a stop cylinder 36a formed in the connecting rod main body 31, and a stop member 36b that can slide in the stop cylinder 36a. In the example shown in FIG. 11, the stop cylinder 36 a and the stop member 36 b are arranged such that the axes thereof extend in the width direction of the connecting rod body 31. However, the stop cylinder 36 a and the stop member 36 b may be arranged with a slight angle with respect to the width direction of the connecting rod body 31.

  The stop member 36b is at least partly protruded from the connecting rod body 31 on the second arm 32c side of the eccentric member 32 and within the connecting rod body 31 (that is, in the stop cylinder 36a). It can slide between the retracted positions. The stop member 36b is disposed so as to contact the second arm 32c of the eccentric member 32 at both the protruding position and the retracted position.

  The stop device 36 further includes a third urging spring 36c that urges the stop member 36b to the retracted position. Further, the stop cylinder 36a of the stop device 36 is communicated with the second pin accommodating space 65 through the hydraulic pressure supply oil passage 52 '. As shown in FIG. 14A, the hydraulic supply oil passage 52 ′ is communicated with the second pin housing space 65 at the closed end of the second pin housing space 65. The hydraulic supply oil passage 52 ′ is disposed at substantially the same position as the second control oil passage 58 in the axial direction of the second pin housing space 65.

  The hydraulic pressure supply oil passage 52 ′ communicates with the second pin accommodation space 65 when the second switching pin 62 is moved by the hydraulic pressure supplied from the external oil supply device. As a result, hydraulic oil is supplied from the external oil supply device to the stop cylinder 36a via the second pin housing space 65 and the hydraulic pressure oil passage 52 '. The hydraulic supply oil passage 52 ′ is also formed by cutting from the crank receiving opening 41 with a drill or the like. Accordingly, an extension oil passage 52a 'coaxial with the hydraulic supply oil passage 52' is formed on the side of the crank receiving opening 41 of the hydraulic supply oil passage 52 '. As shown in FIG. 13, the extension oil passage 52 a ′ is closed by the bearing metal 71.

  In the stop device 36 configured as described above, when the hydraulic pressure higher than a predetermined level is not supplied to the stop cylinder 36a via the hydraulic pressure supply oil passage 52 ', the stop member 36b is retracted by the action of the third biasing spring 36c. Pulled into position. On the other hand, when a hydraulic pressure higher than a predetermined level is supplied to the stop cylinder 36a via the hydraulic supply oil passage 52 ', the stop member 36b is moved to the protruding position by the action of the hydraulic oil supplied to the stop cylinder 36a. .

<Operation of variable length connecting rod>
Next, the operation of the variable-length connecting rod 6 ′ will be described with reference to FIGS. FIG. 15 is a schematic diagram for explaining the operation of the variable-length connecting rod 6 ′ when a medium hydraulic pressure is supplied to the switching pins 61 and 62 and the stop member 36b. FIG. 16 is a schematic diagram for explaining the operation of the variable-length connecting rod 6 ′ when high hydraulic pressure is supplied to the switching pins 61 and 62 and the stop member 36b. FIG. 17 is a schematic diagram for explaining the operation of the variable-length connecting rod 6 ′ when low hydraulic pressure is supplied to the switching pins 61 and 62. FIG. 18 is a side sectional view schematically showing the variable-length connecting rod 6 ′ according to the second embodiment. FIG. 18A shows a state where the flow direction switching mechanism 35 is in the first state and the stop member 36b is in the retracted position. FIG. 18B shows a state where the flow direction switching mechanism 35 is in the first state and the stop member 36b is in the protruding position. FIG. 18C shows a state where the flow direction switching mechanism 35 is in the second state and the stop member 36b is in the retracted position.

  The internal combustion engine 1 further includes an oil supply device 75 and an electronic control unit (ECU) 40. The oil supply device 75 supplies hydraulic pressure to the first switching pin 61 via the first control oil passage 57 and supplies hydraulic pressure to the second switching pin 62 and the stop member 63b via the second control oil passage 58. . The oil supply device 75 is disposed outside the connecting rod body 31 and is controlled by the ECU 40. Therefore, the ECU 40 can control the hydraulic pressure supplied to the first switching pin 61, the second switching pin 62, and the stop member 63b by the oil supply device 75. In the present embodiment, hydraulic oil is supplied from the same oil supply device 75 to the first switching pin 61, the second switching pin 62, and the stop member 36b of the flow direction switching mechanism 35.

  Here, the hydraulic oil pressure at which the operating positions of the first switching pin 61 and the second switching pin 62 are switched, that is, the hydraulic oil pressure at which the flow direction switching mechanism 35 is switched between the first state and the second state. The first threshold is assumed. The first threshold value is determined according to the cross-sectional area of the switching pins 61 and 62 (or the cross-sectional area of the pin accommodating spaces 64 and 65), the elastic coefficient of the biasing springs 67 and 68, and the like. Similarly, the pressure at which the operating position of the stop member 36b switches between the protruding position and the retracted position is set as the second threshold value. The second threshold value is determined according to the cross-sectional area of the stop member 36b (or the cross-sectional area of the stop cylinder 36a), the elastic coefficient of the third urging spring 83, and the like. In the present embodiment, the first threshold value is smaller than the second threshold value. Therefore, when the pressure of the hydraulic oil supplied from the oil supply device 75 is increased, the operating positions of the first switching pin 61 and the second switching pin 62 are switched first, and the flow direction switching mechanism 35 is in the second state. To the first state. Thereafter, when the pressure of the hydraulic oil supplied from the oil supply device 75 is further increased, the stop member 36b moves from the retracted position to the protruding position.

  In the present embodiment, the variable length connecting rod 6 ′ further includes a hydraulic pressure switching mechanism 90. The hydraulic pressure switching mechanism 90 is disposed between the oil supply device 75 and the control oil passages 57 and 58. The hydraulic pressure switching mechanism 90 includes a three-way valve 91 that communicates with the oil supply device 75 and three oil passages 92 to 94 that communicate with the three-way valve 91. The three-way valve 91 is controlled by the ECU 40.

  The three oil passages 92 to 94 are each provided with a relief valve, and the release pressures of these relief valves are different from each other. In the example shown in FIGS. 15 to 17, the relief valve release pressure P <b> 1 provided in the oil passage 92, the relief valve release pressure P <b> 2 provided in the oil passage 93, and the relief valve release provided in the oil passage 94. The release pressure decreases in the order of the pressure P3 (P1> P2> P3). In addition, a relief valve is provided between the oil passage 92 and the oil passage 93 and is released when the pressure in the oil passage 93 becomes high. A relief valve is provided that is released when the pressure increases. The relief pressure P4 of the relief valve provided between these oil passages is set lower than the relief pressure P3 of the relief valve provided in the oil passage 94. In addition, the oil passage 92 communicates with the control oil passages 57 and 58.

  In the hydraulic pressure switching mechanism 90 configured as described above, the hydraulic pressure supplied to the control oil passages 57 and 58 becomes medium when the oil supply device 75 is communicated with the oil passage 93 by the three-way valve 91. In the present embodiment, the oil pressure at this time is higher than the first threshold and lower than the second threshold. Since the hydraulic pressure at this time is higher than the first threshold value, the switching pins 61 and 62 are positioned at the first positions moved against the urging by the urging springs 67 and 68, respectively, as shown in FIG. To do. As a result, the piston communication oil passage 51 and the first space communication oil passage 53 are communicated by the communication passage 61c of the first switching pin 61, and the oil supply device 75 and the fourth space are communicated by the communication passage 62c of the second switching pin 62. The communication oil passage 56 is communicated. Therefore, the hydraulic cylinder 33 a is connected to the secondary side of the check valve 63, and the oil supply device 75 is connected to the primary side of the check valve 63.

  Here, the check valve 63 is configured such that the first space communication oil path 53 and the third space communication oil path 55 communicate with each other from the primary side where the second space communication oil path 54 and the fourth space communication oil path 56 communicate with each other. The flow of hydraulic oil to the side is allowed, but the reverse flow is prohibited. Therefore, in the state shown in FIG. 15, hydraulic oil flows from the fourth space communication oil path 56 to the first space communication oil path 53, but conversely, no hydraulic oil flows.

  As a result, in the state shown in FIG. 15, the hydraulic oil passes through the oil passage from the oil supply device 75 in the order of the fourth space communication oil passage 56, the first space communication oil passage 53, and the piston communication oil passage 51. 33a. However, the hydraulic oil in the hydraulic cylinder 33a cannot be discharged from the hydraulic cylinder 33a. Therefore, when the hydraulic pressure exceeding the first threshold is supplied from the oil supply device 75, the flow direction switching mechanism 35 permits the hydraulic oil to be supplied to the hydraulic cylinder 33a and discharges the hydraulic oil from the hydraulic cylinder 33a. It can be said that it is in the first state prohibiting this.

  At this time, hydraulic oil is supplied to the hydraulic cylinder 33a, and the hydraulic piston 33b rises. Further, since the hydraulic pressure at this time is lower than the second threshold value, the stop member 36b is arranged at the retracted position as shown in FIG. As a result, as shown in FIG. 18A, the eccentric member 32 is rotated to the first position where it is most rotated in the direction of the arrow in the figure. As a result, the position of the piston pin receiving opening 32d rises most. Therefore, the length between the center of the crank receiving opening 41 and the center of the piston pin receiving opening 32d, that is, the effective length of the connecting rod 6 'is the longest, and becomes L1 in the figure. Note that the rotation of the eccentric member 32 in the direction of the arrow in FIG. 18A is stopped when the rotation restricting portion 32e of the eccentric member 32 comes into contact with the stop member 36b disposed at the retracted position.

  On the other hand, as shown in FIG. 16, when the oil supply device 75 is in communication with the oil passage 92 by the three-way valve 91 in the hydraulic pressure switching mechanism 90, the hydraulic pressure supplied to the control oil passages 57 and 58 becomes high. In the present embodiment, the oil pressure at this time is a pressure higher than the second threshold value. Accordingly, since the hydraulic pressure at this time is higher than the first threshold, the switching pins 61 and 62 are moved against the urging by the urging springs 67 and 68, respectively, similarly to the state shown in FIG. Located in one position.

  As a result, the flow direction switching mechanism 35 is in the first state, and the hydraulic piston 33b is raised. Further, since the hydraulic pressure at this time is higher than the second threshold value, the stop member 82 is arranged at the protruding position as shown in FIG. As a result, as shown in FIG. 18B, the eccentric member 32 is rotated to the third position in the direction of the arrow in FIG. The rotational angle of the eccentric member 32 at this time is slightly smaller than the state shown in FIG. As a result, the position of the piston pin receiving opening 32d is lowered from the most raised position. Accordingly, the effective length of the connecting rod 6 'is shorter than that in the state shown in FIG. 18A, and becomes L2 in the drawing. The rotation of the eccentric member 32 is stopped when the rotation restricting portion 32e of the eccentric member 32 comes into contact with the stop member 36b arranged at the protruding position.

  On the other hand, as shown in FIG. 17, when the oil supply device 75 is in communication with the oil passage 94 by the three-way valve 91 in the oil pressure switching mechanism 90, the oil pressure supplied to the control oil passages 57 and 58 becomes low. In the present embodiment, the oil pressure at this time is set to a pressure lower than the first threshold value. Accordingly, since the hydraulic pressure at this time is lower than the first threshold value, the switching pins 61 and 62 are positioned at the second positions urged by the urging springs 67 and 68, respectively, as shown in FIG. As a result, the piston communication oil passage 51 and the second space communication oil passage 54 are communicated by the communication passage 61 c of the first switching pin 61. In addition, the third space communication oil passage 55 and the discharge oil passage 60 are communicated with each other by the circumferential groove 62 a of the second switching pin 62. Therefore, the hydraulic cylinder 33 a is connected to the primary side of the check valve 63, and the drain oil passage 60 is connected to the secondary side of the check valve 63.

  With the action of the check valve 63 described above, in the state shown in FIG. 17, the hydraulic oil in the hydraulic cylinder 33 a is discharged from the piston communication oil path 51, the second space communication oil path 54, the third space communication oil path 55, The oil passage 60 is discharged to the outside of the connecting rod body 31 through the oil passage. However, hydraulic oil cannot be supplied to the hydraulic cylinder 33a from the discharge oil passage 60 side. Therefore, when the hydraulic pressure less than the first threshold is supplied from the oil supply device 75, the flow direction switching mechanism 35 prohibits the supply of the hydraulic oil to the hydraulic cylinder 33a and discharges the hydraulic oil from the hydraulic cylinder 33a. It can be said that it is in the second state that permits this.

  At this time, the hydraulic oil is discharged from the hydraulic cylinder 33a to the outside of the connecting rod body 31, and the hydraulic piston 33b is lowered. At this time, since the hydraulic pressure is not supplied to the stop member 36b, the stop member 36b is disposed at the retracted position as shown in FIG. As a result, as shown in FIG. 18C, the eccentric member 32 is rotated to the second position that is most rotated in the direction of the arrow in the figure. As a result, the position of the piston pin receiving opening 32d is lowered most. Therefore, the effective length of the connecting rod 6 'is the shortest, and becomes L3 in the figure. At this time, the rotation of the eccentric member 32 in the direction of the arrow in FIG. 18C is stopped when the hydraulic piston 33b contacts the bottom of the hydraulic cylinder 33a.

  In the state shown in FIG. 18C, when an upward inertia force acts on the piston pin 21 by the reciprocating motion of the piston 5 in the cylinder 15, the hydraulic piston 33b tends to rise. However, since the flow of hydraulic oil to the hydraulic cylinder 33a is prohibited by the flow direction switching mechanism 35, hydraulic oil is not supplied to the hydraulic cylinder 33a. For this reason, a negative pressure is generated in the hydraulic cylinder 33a, and the position of the hydraulic piston 33b and thus the rotational position of the eccentric member 32 are held by this negative pressure.

  In the present embodiment, the stop device 36 is configured to switch the stop position of the rotation of the eccentric member 32 to one side between the third position and the first position between the first position and the second position. ing. For this reason, the rotational position of the eccentric member 32 can be switched in three stages by the flow direction switching mechanism 35 and the stop device 36. As a result, the effective length of the connecting rod 6 'can be switched to three stages, and in the internal combustion engine 1 provided with the connecting rod 6', the mechanical compression ratio can be changed to three stages.

<Supply of lubricating oil>
In the present embodiment, the small diameter end portion 31 b of the connecting rod body 31 is formed with a lubricating oil hole 311 that allows the outside of the connecting rod body 31 to communicate with the eccentric member receiving opening 42. The lubricating oil hole 311 extends in the radial direction of the small diameter end portion 31b. The eccentric member 32 is formed with a through passage that allows the lubricating oil hole 311 and the piston pin receiving opening 32d to communicate with each other when at least the eccentric member 32 is in the first position, the second position, and the third position.

  In the present embodiment, the through path includes a first through hole 321, a second through hole 322, and a third through hole 323. The first through-hole 321, the second through-hole 322, and the third through-hole 323 extend in the radial direction of the sleeve 32a of the eccentric member 32, and are formed between the outer peripheral surface of the sleeve 32a and the inner surface of the piston pin receiving opening 32d. The sleeve 32a is penetrated between them. The first through hole 321, the second through hole 322, and the third through hole 323 are separated from each other in the circumferential direction of the sleeve 32a. When the eccentric member 32 is in the first position, the first through hole 321 is formed so that the circumferential position of the lubricating oil hole 311 of the small-diameter end portion 31b coincides. The second through hole 322 is formed so that the position in the circumferential direction coincides with the lubricating oil hole 311 of the small diameter end portion 31b when the eccentric member 32 is in the second position. When the eccentric member 32 is in the third position, the third through hole 323 is formed so that the circumferential position thereof coincides with the lubricating oil hole 311 of the small diameter end portion 31b. For this reason, the circumferential distance between the first through hole 321 and the second through hole 322 is the rotation distance of the sleeve 32a when the eccentric member 32 is rotated between the first position and the second position. be equivalent to. The circumferential distance between the first through hole 321 and the third through hole 323 is equal to the rotation distance of the sleeve 32a when the eccentric member 32 is rotated between the first position and the third position. The circumferential distance between the second through hole 322 and the third through hole 323 is equal to the rotation distance of the sleeve 32a when the eccentric member 32 is rotated between the second position and the third position.

  As can be seen from FIG. 18A, the first through hole 321 allows the lubricating oil hole 311 and the piston pin receiving opening 32d to communicate with each other when the eccentric member 32 is in the first position. As can be seen from FIG. 18C, the second through hole 322 allows the lubricating oil hole 311 and the piston pin receiving opening 32d to communicate with each other when the eccentric member 32 is in the second position. As can be seen from FIG. 18B, the third through hole 323 allows the lubricating oil hole 311 and the piston pin receiving opening 32d to communicate with each other when the eccentric member 32 is in the third position.

  The lubricating oil supplied from the oil jet 16 flows into the eccentric member receiving opening 42 through the lubricating oil hole 311 and is supplied between the small diameter end portion 31 b and the eccentric member 32. Further, when the eccentric member 32 is in the first position, the lubricating oil flows into the piston pin receiving opening 32 d through the lubricating oil hole 311 and the first through hole 321, and between the eccentric member 32 and the piston pin 21. Supplied. Further, when the eccentric member 32 is in the second position, the lubricating oil flows into the piston pin receiving opening 32d through the lubricating oil hole 311 and the second through hole 322, and between the eccentric member 32 and the piston pin 21. Supplied. Further, when the eccentric member 32 is in the third position, the lubricating oil flows into the piston pin receiving opening 32d through the lubricating oil hole 311 and the third through hole 323, and between the eccentric member 32 and the piston pin 21. Supplied.

  Therefore, in this embodiment, even when the rotational position of the eccentric member 32 is switched between the first position, the second position, and the third position in order to change the mechanical compression ratio, the sliding portion is lubricated. Oil can be supplied. For this reason, abrasion, seizure, etc. of the piston pin 21, the eccentric member 32, and the connecting rod main body 31 can be suppressed. In the present embodiment, only one lubricating oil hole 311 is formed in the small diameter end portion 31b. For this reason, the fall of the intensity | strength of the connecting rod main body 31 accompanying formation of the oil path of lubricating oil can be suppressed.

<Third embodiment>
Next, the variable length connecting rod 6 ″ according to the third embodiment of the present invention will be described. The configuration and operation of the variable length connecting rod 6 ″ according to the third embodiment are basically the same except for the points described below. This is the same as the configuration and operation of the variable length connecting rod 6 ′ according to the second embodiment.

<Supply of lubricating oil>
Hereinafter, the supply of lubricating oil in the present embodiment will be described with reference to FIGS. 19 is a side sectional view schematically showing the variable length connecting rod 6 ″ according to the third embodiment. FIG. 20 is a schematic exploded perspective view of the vicinity of the small diameter end portion 31b of the connecting rod body 31. 21 is a side sectional view schematically showing the variable length connecting rod 6 ″ according to the third embodiment. FIG. 21A shows a state where the flow direction switching mechanism 35 is in the first state and the stop member 36b is in the retracted position. FIG. 21B shows a state in which the flow direction switching mechanism 35 is in the first state and the stop member 36b is in the protruding position. FIG. 21C shows a state where the flow direction switching mechanism 35 is in the second state and the stop member 36b is in the retracted position.

  In the present embodiment, the small diameter end portion 31 b of the connecting rod body 31 is formed with a lubricating oil hole 311 that allows the outside of the connecting rod body 31 to communicate with the eccentric member receiving opening 42. The lubricating oil hole 311 extends in the radial direction of the small diameter end portion 31b. The eccentric member 32 is formed with a through passage that allows the lubricating oil hole 311 and the piston pin receiving opening 32d to communicate with each other when at least the eccentric member 32 is in the first position, the second position, and the third position.

  In the present embodiment, the through path includes a groove 324 and a through hole 325. The groove 324 is formed in the sleeve 32a of the eccentric member 32 and extends in the rotational direction of the eccentric member 32 (the circumferential direction of the sleeve 32a) so as to communicate with the lubricating oil hole 311 regardless of the rotational position of the eccentric member 32. doing. The extending distance of the groove 324 is set to be equal to or longer than the rotation distance of the sleeve 32a when the eccentric member 32 is rotated between the first position and the second position. In the present embodiment, the extending distance of the groove 324 is equal to the turning distance of the sleeve 32a when the eccentric member 32 is turned between the first position and the second position. Further, the groove 324 is formed so that the circumferential position of one end portion of the groove 324 in the circumferential direction coincides with the lubricating oil hole 311 when the eccentric member 32 is in the first position.

  On the other hand, the through hole 325 extends in the radial direction of the sleeve 32a, and communicates the groove 324 with the piston pin receiving opening 32d. In the present embodiment, the through hole 325 communicates with the groove 324 at the other end in the circumferential direction of the groove 324. The through hole 325 may communicate with the groove 324 at other positions in the circumferential direction. As can be seen from FIGS. 21 (A) to 21 (C), the groove 324 and the through hole 325 communicate the lubricating oil hole 311 and the piston pin receiving opening 32d regardless of the rotational position of the eccentric member 32.

  The lubricating oil supplied from the oil jet 16 flows into the eccentric member receiving opening 42 through the lubricating oil hole 311 and is supplied between the small diameter end portion 31 b and the eccentric member 32. Regardless of the rotational position of the eccentric member 32, the lubricating oil flows into the piston pin receiving opening 32 d through the lubricating oil hole 311, the groove 324 and the through hole 325, and between the eccentric member 32 and the piston pin 21. To be supplied.

  Therefore, in this embodiment, even when the rotational position of the eccentric member 32 is switched between the first position, the second position, and the third position in order to change the mechanical compression ratio, the sliding portion is lubricated. Oil can be supplied. In particular, in the present embodiment, even when the rotational position of the eccentric member 32 is between the first position and the third position or between the third position and the second position, lubrication is performed via the groove 324. Since the oil hole 311 and the through hole 325 communicate with each other, lubricating oil can be supplied to the sliding portion. For this reason, abrasion, seizure, etc. of the piston pin 21, the eccentric member 32, and the connecting rod main body 31 can be suppressed. In the present embodiment, only one lubricating oil hole 311 is formed in the small diameter end portion 31b. For this reason, the fall of the intensity | strength of the connecting rod main body 31 accompanying formation of the oil path of lubricating oil can be suppressed.

  The preferred embodiments according to the present invention have been described above, but the present invention is not limited to these embodiments, and various modifications and changes can be made within the scope of the claims. For example, the variable length connecting rods 6 ′, 6 ″ in the second embodiment and the third embodiment may not include the stop device 36. In this case, the effective length of the variable length connecting rods 6 ′, 6 ″, and thus the internal combustion The mechanical compression ratio of the engine 1 is changed in two stages. Further, in the variable length connecting rod 6 in the first embodiment, the through passage formed in the eccentric member 32 may include the groove 324 and the through hole 325 as in the third embodiment.

  In this specification, the rising of the hydraulic pistons 33a, 34a means that the hydraulic pistons 33a, 34a move so as to approach the small diameter end portion 31b of the connecting rod body 31, and the lowering of the hydraulic pistons 33a, 34a. Means that the hydraulic pistons 33a, 34a move away from the small diameter end portion 31b.

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 6, 6 ', 6 "Connecting rod 21 Piston pin 22 Crank pin 31 Connecting rod main body 31a Large diameter end part 31b Small diameter end part 32 Eccentric member 32d Piston pin receiving opening 41 Crank receiving opening 42 Eccentric member receiving opening 311 Lubricating oil hole 321 First through hole 322 Second through hole 323 Third through hole 324 Groove 325 Through hole

Claims (6)

An eccentric member provided with a piston pin receiving opening for receiving the piston pin;
A connecting rod body having a large diameter end portion provided with a crank receiving opening for receiving a crank pin and a small diameter end portion provided with an eccentric member receiving opening for receiving the eccentric member;
In the variable length connecting rod, the eccentric member rotates between a first position and a second position so as to change a length between the center of the piston pin receiving opening and the center of the crank receiving opening.
The small-diameter end is formed with only one lubricating oil hole that communicates the outside of the connecting rod body and the eccentric member receiving opening, and at least the eccentric member is in the first position and the second position. A variable-length connecting rod characterized in that a through passage is formed for communicating the lubricating oil hole and the piston pin receiving opening when in the position. A stop device configured to switch between a first position and a third position between the first position and the second position, a stop position of rotation of the eccentric member to one side;
The through passage is formed so as to communicate the lubricating oil hole and the piston pin receiving opening when at least the eccentric member is in the first position, the second position, and the third position. Item 2. The variable length connecting rod according to Item 1.   The through passage includes a first through hole that allows the lubricating oil hole and the piston pin receiving opening to communicate with each other when the eccentric member is in the first position, and when the eccentric member is in the second position. The variable-length connecting rod according to claim 1, further comprising a second through hole that communicates the lubricating oil hole with the piston pin receiving opening.   The through passage includes a first through hole that allows the lubricating oil hole and the piston pin receiving opening to communicate with each other when the eccentric member is in the first position, and when the eccentric member is in the second position. A second through hole for communicating the lubricating oil hole and the piston pin receiving opening; a third through hole for communicating the lubricating oil hole and the piston pin receiving opening when the eccentric member is in the third position; The variable length connecting rod according to claim 2, comprising:   The through passage communicates the groove extending in the rotational direction of the eccentric member so as to communicate with the lubricating oil hole regardless of the rotational position of the eccentric member, and the groove and the piston pin receiving opening. The variable length connecting rod according to claim 1 or 2, comprising a through hole. A variable compression ratio internal combustion engine capable of changing a mechanical compression ratio,
A variable length connecting rod according to any one of claims 1 to 5, wherein the length is changed between the center of the piston pin receiving opening and the center of the crank receiving opening by the variable length connecting rod. A variable compression ratio internal combustion engine in which the compression ratio is changed.

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