JP5673346B2 - Lower link of multi-link engine - Google Patents

Description

  The present invention relates to a structure of a lower link of a multi-link engine.

  2. Description of the Related Art Conventionally, there are known multi-link engines in which a piston and a crankshaft are connected via an upper link and a lower link, and the compression ratio is variable by controlling the posture of the lower link. In a multi-link engine, the attitude of the lower link is controlled via a control link connected to the lower link.

  The lower link is a link member provided to be rotatable with respect to the crankpin of the crankshaft. The lower link has a split structure that sandwiches the crank pin, and includes a first link portion and a second link portion. A semicircular bearing metal is provided in each of the concave portions of the first link portion and the second link portion, and the lower link is attached to the crank pin via these bearing metals.

  In a state before the first link portion and the second link portion are fastened, both ends of the bearing metal installed in the first link portion protrude from the concave portion of the first link portion, and the bearing metal disposed in the second link portion. Both ends protrude from the recesses of the second link portion. The protruding height at both ends of the bearing metal is called the crush height. The first link portion and the second link portion are fastened in a state where both ends of each bearing metal are in contact with each other, and the bearing metal is pushed into the recess, whereby the bearing metal is tightly fixed to the inner peripheral surface of the recess.

  In the lower link of the multi-link engine as described above, the bearing metal may rotate with respect to the concave portions of the first link portion and the second link portion based on the load input from the crankshaft during engine operation. When the bearing metal is turned inward, the positions of the oil passages formed in the first link part and the second link part and the oil passages formed in the bearing metal are shifted, and the flow of the lubricating oil is deteriorated.

  In Patent Document 1, a flange portion is formed at an end portion in the width direction of the bearing metal, and contact portions that can contact the flange portion are formed on the side surfaces of the first link portion and the second link portion. A lower link for preventing adduction is disclosed.

JP 2006-183815 A

  However, the lower link described in Patent Document 1 has a problem that the bearing metal, the first link portion, and the second link portion have special shapes, respectively, and the lower link manufacturing cost increases.

  Further, in order to prevent the inner rotation of the bearing metal, it is conceivable that the crush height is set to be larger than the conventional one and the contact surface pressure of the bearing metal with respect to the first link portion and the second link portion is increased as a whole. However, when the contact surface pressure of the bearing metal is increased as a whole, the bearing metal is likely to deteriorate in a region where a load input from the crankshaft is high (high load region) during engine operation.

  Therefore, the present invention has been made paying attention to such a problem, and an object thereof is to provide a lower link of a multi-link engine that can suppress internal rotation and deterioration of a bearing metal.

  A lower link of a multi-link engine according to the present invention includes a first link portion having a recess, and a recess that forms a through hole through which a crankshaft can be inserted corresponding to the recess of the first link portion. And a semicircular bearing metal installed in each recess of the first link portion and the second link portion. Furthermore, the lower link is provided corresponding to a low load region set based on the load distribution in the bearing metal inner circumferential direction of the load input from the crankshaft to the bearing metal when the engine is operated, and the contact surface of the bearing metal with respect to the recess A surface pressure increasing portion for increasing the pressure is provided.

  According to the present invention, since the contact surface pressure of the bearing metal in the low load region is increased by the surface pressure increasing portion, the inversion of the bearing metal can be suppressed with a simpler configuration than the conventional one. In addition, since the contact surface pressure of the bearing metal in the high load region is not increased, deterioration of the bearing metal can be suppressed.

1 is a longitudinal sectional view of a multi-link engine according to a first embodiment of the present invention. It is a front view of the lower link constituting the compression ratio variable mechanism, It is a figure which shows the relationship between the contact surface pressure of a bearing metal, and slippage. It is an enlarged view of the lower link in the vicinity of the position where the bearing metal is disposed. It is a front view of the lower link of the multilink type engine by a 2nd embodiment. It is a front view of the lower link of the multilink type engine by the modification of 2nd Embodiment.

  Embodiments of the present invention will be described below with reference to the drawings.

(First embodiment)
With reference to FIG.1 and FIG.2, the structure of the multilink type engine 100 by 1st Embodiment of this invention is demonstrated. FIG. 1 is a schematic configuration diagram of a multi-link engine 100 according to the first embodiment. FIG. 2 is a front view of the lower link 200 of the compression ratio variable mechanism 20 provided in the multi-link engine 100.

  As shown in FIG. 1, the multi-link engine 100 is an in-line four-cylinder engine for a vehicle. The multi-link engine 100 includes a variable compression ratio mechanism 20 that can change the compression ratio by changing the top dead center position of the piston 10.

  The compression ratio variable mechanism 20 includes an upper link 21 and a lower link 200 for connecting the piston 10 and the crankshaft 30, and a control link 22 for controlling the posture of the lower link 200.

  The upper link 21 is a link member that connects the lower link 200 and the piston 10 that slides along the cylinder 11. The upper end of the upper link 21 is rotatably connected to the piston 10 via a piston pin 41. A lower end of the upper link 21 is rotatably connected to the lower link 200 via an upper pin 42.

  As shown in FIGS. 1 and 2, the lower link 200 is a link member having a two-part structure that is rotatably provided on the crankpin 31 of the crankshaft 30. The lower link 200 includes a first link part 210 and a second link part 220 fastened to the first link part 210. The lower link 200 is connected to the upper link 21 via the upper pin 42 provided at the corner portion 214 of the first link portion 210, and is controlled via the control pin 43 provided at the corner portion 224 of the second link portion 220. The link 22 is connected.

  The first link part 210 has a semicircular recess 211 on the contact surface (divided surface) that contacts the second link part 220, and the second link part 220 contacts the first link part 210. A semicircular recess 221 is provided on the surface (divided surface). In a state where the second link portion 220 is fastened to the first link portion 210, the insertion hole through which the crank pin 31 of the crankshaft 30 is inserted by the recess 211 of the first link portion 210 and the recess 221 of the second link portion 220. 230 is formed.

  Also, semicircular bearing metals 212 and 222 are provided in the concave portion 211 of the first link portion 210 and the concave portion 221 of the second link portion 220, respectively. These bearing metals 212 and 222 are arc-shaped plate members, and the bearing metal 212 and the bearing metal 222 form one sliding bearing.

  In a state before the first link part 210 and the second link part 220 are fastened, the bearing metal 212 is set with a crash height at which the circumferential end protrudes from the contact surface of the first link part 210. The bearing metal 222 is provided with a crush height whose end in the circumferential direction protrudes from the contact surface of the second link portion 220. The first link portion 210 and the second link portion 220 are fastened so that the crush height becomes 0 in a state where the circumferential ends of the bearing metals 212 and 222 are in contact with each other, so that the bearing metal 212 becomes the first link portion. The bearing metal 222 is firmly fixed to the inner peripheral surface of the concave portion 221 of the second link portion 220.

  The lower link 200 configured as described above is rotatably attached to the crankpin 31 of the crankshaft 30 via bearing metals 212 and 222 disposed in the insertion hole 230.

  In the lower link 200, the thickness in the width direction at the edge portions 213 and 223 along the outer edges of the recesses 211 and 221 and the thickness in the width direction at the corner portions 214 and 224 of the first link portion 210 and the second link portion 220 are as follows. It is set to be thicker than the thickness in the width direction at the central portions 215 and 225 between the edge portions 213 and 223 and the corner portions 214 and 224.

  As shown in FIG. 1, the crankshaft 30 is a rotating shaft that includes a crankpin 31, a journal 32, and a counterweight 33. The center of the crankpin 31 is eccentric from the center of the journal 32 by a predetermined amount. The counterweight 33 is formed on a crank arm that connects the crankpin 31 and the journal 32, and reduces a vibration component in the piston motion.

  The control link 22 is a link member for controlling the posture of the lower link 200. The upper end of the control link 22 is rotatably connected to the lower link 200 via a control pin 43. The lower end of the control link 22 is rotatably connected to the eccentric portion 23A of the control shaft 23.

  The control shaft 23 is disposed in parallel with the crankshaft 30 and is rotatably supported by the cylinder block. The eccentric portion 23A of the control shaft 23 is formed at a position eccentric by a predetermined amount from the control shaft axis. The control shaft 23 is rotationally driven by an actuator (not shown). As the control shaft 23 rotates, the eccentric portion 23A turns around the control shaft axis.

  When the lower link 200 is tilted so that the eccentric portion 23A is moved by the rotation of the control shaft 23 and the position of the upper pin 42 is raised, the top dead center position of the piston 10 is raised. Thereby, the compression ratio of the multi-link engine 100 becomes high. On the other hand, when the eccentric part 23A moves and the lower link 200 is tilted so that the position of the upper pin 42 is lowered, the top dead center position of the piston 10 is lowered. Thereby, the compression ratio of the multi-link engine 100 becomes low.

  In the multi-link engine 100, for example, a low compression ratio is set to prevent knocking in a high load operation region, and a high compression ratio is set to improve output in a low load and medium load operation region where knocking is difficult to occur. Is done.

  By the way, in the lower link 200 of the multi-link engine 100, since the bearing metals 212 and 222 function as sliding bearings, the bearing metals 212 and 222 rotate with respect to the recesses 211 and 221 during engine operation. Need to prevent.

  FIG. 3 is a diagram illustrating the relationship between the sliding amount of a predetermined portion of the bearing metal 212 and the contact surface pressure in one combustion cycle. The slip amount is an index representing the rotation amount of the bearing metal 212 with respect to the reference position, and the contact surface pressure is an index representing the contact pressure of the bearing metal 212 with respect to the recess 211 of the first link portion 210.

  During engine operation, the load input from the crankpin 31 of the crankshaft 30 to the bearing metals 212 and 222 changes as the crankshaft 30 rotates. Therefore, as shown in FIG. 3, the contact surface pressure of the bearing metal 212 also changes according to the rotation of the crankshaft 30.

  In the low contact surface pressure region where the contact surface pressure of the bearing metal 212 is low, the slip amount of the bearing metal 212 changes, and the bearing metal 212 is inwardly rotated with respect to the recess 211. On the other hand, as shown in the broken line region of FIG. 3, in the high contact surface pressure region where the contact surface pressure is high, the sliding amount of the bearing metal 212 is substantially constant, and the internal rotation of the bearing metal 212 does not occur.

  Therefore, in the lower link 200 of the multi-link engine 100 according to the present embodiment, the contact surface pressure of the bearing metals 212 and 222 with respect to the recesses 211 and 221 is partially increased to prevent the inner rotation of the bearing metals 212 and 222. .

  FIG. 4 is an enlarged view of the lower link 200 in the vicinity of the position where the bearing metals 212 and 222 are disposed.

  The broken line L1 in FIG. 4 shows the load distribution in the bearing metal inner circumferential direction of the load input from the crankshaft 30 to the bearing metals 212 and 222 in one combustion cycle when the maximum torque is generated. A solid line L2 in FIG. 4 shows the load distribution in the bearing metal inner circumferential direction of the load input from the crankshaft 30 to the bearing metals 212 and 222 in one combustion cycle when the maximum output is generated. Based on the load distribution of the broken line L1 and the solid line L2, the bearing metals 212 and 222 have a high load area A in which the input load is higher than a predetermined value and a low load area in which the input load is lower than the predetermined value along the inner circumferential direction. And B.

  In the lower link 200, protrusions 212 </ b> A and 222 </ b> A are formed on the inner peripheral surfaces of the bearing metals 212 and 222 corresponding to the low load region B in order to prevent the inner rotation of the bearing metals 212 and 222. The protrusions 212A and 222A are formed so as to protrude from the inner peripheral surfaces of the bearing metals 212 and 222 toward the inside in the bearing metal radial direction. In this embodiment, as shown in FIGS. 2 and 4, the protruding portion 212 </ b> A of the bearing metal 212 and the protruding portion 222 </ b> A of the bearing metal 222 are formed to face each other. It is not limited and is arbitrarily selected in the low load region B.

  Although a lubricating oil film is interposed between the bearing metals 212 and 222 and the crank pin 31 of the crankshaft 30, the lubricating oil film becomes thin at the positions where the protruding portions 212A and 222A are formed. The load from the shaft 30 is likely to act, and the contact surface pressure of the bearing metals 212 and 222 is increased in the low load region B. Thus, the protrusions 212A and 222A function as a surface pressure increasing portion that increases the contact surface pressure of the bearing metals 212 and 222.

  As described above, the lower link 200 of the multi-link engine 100 according to the first embodiment can obtain the following effects.

  Since the protruding portions 212A and 222A are formed on the inner peripheral surfaces of the bearing metals 212 and 222 at positions corresponding to the low load region B, the contact surface pressure of the bearing metals 212 and 222 at the protruding portion forming position is reduced during engine operation. Can be increased. Therefore, it is possible to suppress the internal rotation of the bearing metals 212 and 222 with a simpler configuration than the conventional one.

  Further, if the contact surface pressure of the bearing metals 212 and 222 is increased in the high load region A, the bearing metals 212 and 222 are liable to deteriorate. However, in the lower link 200, the contact surfaces of the bearing metals 212 and 222 in the low load region B. Since the pressure is increased, deterioration of the bearing metals 212 and 222 can be suppressed.

(Second Embodiment)
The lower link 200 of the multi-link engine 100 according to the second embodiment will be described with reference to FIG. FIG. 5 is a front view of the lower link 200 of the multi-link engine 100 according to the second embodiment.

  The lower link 200 in the second embodiment has substantially the same configuration as the lower link in the first embodiment, but differs in how to increase the contact surface pressure of the bearing metals 212 and 222 in the low load region B. Hereinafter, the difference will be mainly described.

  As shown in FIG. 5, in the lower link 200, ribs 216, on the side surfaces of the first link part 210 and the second link part 220 corresponding to the low load region B in order to prevent internal rotation of the bearing metals 212 and 222. 226 is formed.

  The rib 216 is provided at a position corresponding to the low load region B of the bearing metal 212 on the side surface of the first link portion 210, and extends linearly from a position near the recess 211 toward the radially outer side of the bearing metal 212. The The rib 216 is erected on the central portion 215 that is the thin portion of the first link portion 210 so as to connect the edge portion 213 and the corner portion 214 that are the thick portion of the first link portion 210.

  The rib 226 is provided at a position corresponding to the low load region B of the bearing metal 222 on the side surface of the second link portion 220, and extends linearly from a position near the recess 221 toward the radially outer side of the bearing metal 222. The The rib 226 is erected on the central part 225 which is a thin part of the second link part 220 so as to connect the edge part 223 and the corner part 224 which are thick part of the second link part 220.

  At the position where the ribs 216 and 226 are formed, the rigidity of the first link part 210 and the second link part 220 becomes high, and even if a load is input from the crankshaft 30 during engine operation, the first link part 210 and the second link Since the portion 220 is less likely to be deformed, the contact surface pressure of the bearing metals 212 and 222 is increased in the low load region B. As described above, the ribs 216 and 226 function as a surface pressure increasing portion that increases the contact surface pressure of the bearing metals 212 and 222.

  As described above, the lower link 200 of the multi-link engine 100 according to the second embodiment can obtain the following effects.

  In the lower link 200, ribs 216 are formed on the side surface of the first link portion 210 from the position near the recess 211 toward the radially outer side of the bearing metal 212 so as to correspond to the low load region B, and the second link portion 220. Ribs 226 are formed on the side surfaces of the bearing metal 222 from the position near the recess 221 toward the outside in the radial direction of the bearing metal 222. Thereby, the contact surface pressure of the bearing metals 212 and 222 corresponding to the rib forming position can be increased during engine operation. Therefore, it is possible to suppress the internal rotation of the bearing metals 212 and 222 with a simpler configuration than the conventional one.

  Further, if the contact surface pressure of the bearing metals 212 and 222 is increased in the high load region A, the bearing metals 212 and 222 are liable to deteriorate. However, in the lower link 200, the contact surfaces of the bearing metals 212 and 222 in the low load region B. Since the pressure is increased, the occurrence of deterioration of the bearing metals 212 and 222 can be suppressed.

  Next, a lower link 200 according to a modification of the second embodiment will be described with reference to FIG. FIG. 6 is a front view of a lower link 200 according to a modification.

  A vector B1 in FIG. 6 represents the input direction and magnitude of the maximum load in the high load region A set based on the broken line L1 in FIG. Vectors B2 and B3 in FIG. 6 represent the input direction and magnitude of the maximum load in the high load region A set based on the solid line L2 in FIG.

In the lower link 200 according to the modified example, four ribs 216A, 216B, on the side surfaces of the first link part 210 and the second link part 220 corresponding to the low load region B in order to prevent the inner rotation of the bearing metals 212, 222, The ribs 216A and the ribs 216B in which the holes 226A and 226B are formed are provided at positions corresponding to the low load region B of the bearing metal 212 on the side surface of the first link portion 210, and the radial direction of the bearing metal 212 from the position near the recess 211 It extends in a straight line toward the outside. The rib 216A and the rib 216B are arranged so as to be line symmetric with respect to the input direction of the maximum load indicated by the vector B3.

  The ribs 226A and the ribs 226B are provided at positions corresponding to the low load region B of the bearing metal 222 on the side surface of the second link portion 220, and linearly extend from the position near the recess 221 toward the radially outer side of the bearing metal 222. It is extended. The rib 226A and the rib 226B are arranged so as to be line symmetric with respect to the input direction of the maximum load indicated by the vector B1.

  The ribs 216B of the first link part 210 and the ribs 226B of the second link part 220 are arranged so as to be line symmetric with respect to the input direction of the maximum load indicated by the vector B2.

  In the lower link 200 according to the modified example, the ribs 216A, 216B, 226A, and 226B are provided so as to correspond to the low load region B. Therefore, the same effect as in the second embodiment can be obtained. In the lower link 200, the ribs 216A, 216B, 226A, and 226B are arranged so as to be line-symmetric with respect to the input direction of the maximum load in the high load region A. The deformation of the second link portion 220 can be efficiently suppressed, and the internal rotation of the bearing metals 212 and 222 caused by the deformation difference between the first link portion 210 and the second link portion 220 can be suppressed. Become.

  Note that the present invention is not limited to the above-described embodiment, and it is obvious that various modifications can be made within the scope of the technical idea.

100 Double-link engine 10 Piston 30 Crankshaft 31 Crank pin 200 Lower link 210 First link portion 211 Recessed portion 212 Bearing metal 212A Protruding portion 216 Rib 216A Rib 216B Rib 220 Second link portion 221 Recessing portion 222 Bearing metal 222A Protruding portion 226 Rib 226A Rib 226B Rib 230 Insertion hole

Claims (4)

In the lower link of a multi-link engine in which the compression ratio is variable by connecting the piston and crankshaft by a plurality of link members,
A first link portion having a recess;
A second link portion that has a recess that forms an insertion hole through which the crankshaft can be inserted corresponding to the recess of the first link portion, and is fastened to the first link portion;
A semi-circular bearing metal installed in each recess of the first link part and the second link part;
The contact surface pressure of the bearing metal against the recess is provided corresponding to a low load region set based on the load distribution in the bearing metal inner circumferential direction of the load input from the crankshaft to the bearing metal during engine operation. A lower link of a multi-link engine, characterized by comprising a surface pressure increasing portion for increasing.   The lower link of the multi-link type engine according to claim 1, wherein the surface pressure increasing portion is a protruding portion provided corresponding to the low load region and protruding from an inner peripheral surface of the bearing metal. .   The surface pressure increasing portion is provided corresponding to the low load region, and is a rib extending from the position near the recess toward the outer side in the bearing metal radial direction on the side surfaces of the first link portion and the second link portion. The lower link of the multi-link engine according to claim 1, wherein A plurality of the ribs are provided,
4. The lower link of the multi-link engine according to claim 3, wherein the plurality of ribs are arranged in line symmetry with respect to an input direction of a maximum load input from the crankshaft to the bearing metal. 5. Link.

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