JP2005042907A - Pin connecting structure for link mechanism - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the assemblability and durability by achieving both of securing a contact area between pin bosses 22, 23, 26 and a connection pin 12, and saving weight. <P>SOLUTION: Both links 13, 11 are rotatably connected by a connection pin 12 rotatably penetrated through pin bearing holes 24, 25, 27 of the forked first and bifurcated bosses 22, 23 of the lower link 13 and a third pin boss 26 of the upper link 11 mounted therebetween. Shaft parts 42, 62 of flange members 40, 60 having flanges 41, 61 larger than the first and second pin bearing holes 24, 25 are inserted into a through hole 37 from both ends of the connection pin 12, and engagement faces 43, 63 formed on the shaft parts 42, 62 are engaged and kept into face-contact with each other to assemble the flange members 40, 60 on the connection pin 12. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a pin connection structure used in a link mechanism such as a piston-crank mechanism of a reciprocating internal combustion engine.

  In a reciprocating internal combustion engine, a reciprocating compressor, or the like, a pin coupling structure that couples two link parts rotatably with a coupling pin is used in various parts. For example, Patent Document 1 discloses a pin connection structure in which a piston and a connecting rod of an internal combustion engine are rotatably connected by a piston pin. The piston pin passes through a bifurcated pin boss formed on the piston and a pin boss of a connecting rod disposed between the bifurcated pin bosses, and rotatably connects the piston and the connecting rod.

  In Patent Document 1, the piston pin is rotatable with respect to the piston and the connecting rod, and is generally called a full floating structure. As a similar structure, there is a press-fit structure in which a piston pin is fixed to one connecting rod side pin boss by an interference fit, press fitting, or the like, and is fitted to the other piston side pin boss in a rotatable state. Compared to the press-fit structure, the full floating structure is advantageous in that the frictional force is suppressed to be low, and it is easy to ensure the lubrication performance. However, in the full floating structure, since the piston pin can move not only in the rotational direction but also in the axial direction, some means for preventing the piston pin from dropping off in the axial direction must be provided.

  In the above Patent Document 1, snap ring grooves are formed in the vicinity of both ends of the inner periphery of the pin hole of the piston side pin boss, and snap rings capable of facing and abutting on the axial end surface of the piston pin are fitted in these grooves. The snap ring prevents the piston pin from falling off.

By the way, Patent Document 2 and Patent Document 3 disclose a multi-link type piston-crank mechanism in which a piston and a crank pin of a crankshaft are linked by an upper link and a lower link, and a control link is connected to the lower link. ing. Such a multi-link type piston-crank mechanism has more link parts and more pin connection parts than a single-link type piston-crank mechanism in which the piston and crank pin are linked by a single connecting rod. Specifically, the piston and upper link are connected via a piston pin, the upper link and lower link are connected via an upper pin, and the control link and lower link are connected via a control pin. Is done.
JP 2000-18383 A JP 2001-227367 A JP 2002-61501 A

  In the pin connection structure using the snap ring as in Patent Document 1, since the connection pin such as a piston pin is sandwiched between the snap rings, the length of the connection pin must be shortened compared to the total axial length of the pin boss. The region outside the pin boss in the axial direction from the snap ring does not function as a bearing. For this reason, there is a problem that the contact area between the connecting pin and the pin boss decreases and the stress condition becomes severe, or the axial dimension of the pin boss becomes long, leading to an increase in size and a decrease in engine mountability.

  In particular, in the multi-link type piston-crank mechanism shown in Patent Document 2 and Patent Document 3, the component structure is complicated. Therefore, in the pin connection structure using a snap ring that requires extra axial dimensions, the pin connection It is very difficult to secure the arrangement space for the parts, particularly the arrangement space in the front-rear direction of the engine.

  Further, in the pin connection structure using the above-described snap ring, at the time of assembly, after inserting the piston pin into the pin boss, at least one of the snap rings must be attached to the pin boss. The snap ring is attached by, for example, elastically deforming and shrinking the snap ring while being held by a plier, moving the snap ring to a predetermined ring groove position while maintaining the contracted state, and maintaining the position of the snap ring. The work is to recover from the contracted state and to remove the pliers from the ring. If the snap ring is inadvertently dropped from the pliers during this work, the snap ring may be bounced off due to its own elasticity, causing problems such as loss. Even if the snap ring is fitted in the ring groove of the connecting pin, the assembly work is similarly complicated.

  Instead of the structure using the snap ring as described above, it is also conceivable to fix a flange (washer) member having a diameter larger than the bearing hole of the pin boss to both end surfaces of the connecting pin in the axial direction using screws. However, in this case, there is a fear that the screw is loosened, and it is difficult to ensure durability and reliability.

  The present invention has been made in view of such a problem, and ensures a high level of securing the contact area between the pin boss and the connecting pin and reducing the size and weight of the pin boss, and is easy to assemble and durable. The main purpose is to provide a pin connection structure of a novel link mechanism that is excellent in reliability and reliability.

  With the third bearing hole formed in the second link member coaxially disposed between the first bearing hole and the second bearing hole formed in the first link member, these first to third bearings This is a pin connection structure of a link mechanism that rotatably connects the first link member and the second link member by fitting the connection pin into the hole. A first shaft portion that fits into a pin hole that opens in the axial end surface of the connecting pin, and a first flange that is provided at one axial end of the first shaft portion and has a larger diameter than the first pin bearing hole And a second shaft portion that fits into a pin hole that opens in an axial end surface of the connecting pin, and the second pin bearing is provided at one axial end of the second shaft portion. A second flange member having a second flange that is larger in diameter than the hole. The first engaging portion provided in the first shaft portion engages with the second shaft portion or the connecting pin in the pin hole, so that the first flange is substantially at the opening peripheral portion of the first pin bearing hole. The first flange member is locked in the axial direction with respect to the connecting pin in a state where the first flange member is opposed to the connecting pin. The second engaging portion provided in the second shaft portion engages with the first shaft portion or the connecting pin in the pin hole, so that the second flange is substantially at the opening peripheral portion of the second pin bearing hole. The second flange member is locked in the axial direction with respect to the connecting pin in a state where the second flange member is opposed to the connecting pin.

  The first flange of the first flange member and the second flange of the second flange member prevent the connecting pin from falling off in the axial direction. There is no need to secure an extra pin boss or connecting pin area outside the flange in the flange direction of both flange members, ensuring a high level of contact area between the pin boss and the connecting pin, and miniaturization and weight reduction of the pin boss. Can be compatible.

  When assembling, for example, the shaft portions of both flange members may be pushed into the pin holes from both sides of the connecting pin, and the engaging portions of both shaft portions may be engaged in the pin holes. Compared to the pin connection structure using screws, the assembly work is extremely easy. Moreover, since there is no possibility that the screw will loosen unlike the pin connection structure using the screw, it is excellent in durability and reliability.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows a variable compression ratio mechanism of an internal combustion engine using a multi-link type piston-crank mechanism as an example of a link mechanism to which a pin coupling structure according to the present invention is applied. A piston 1 is slidably disposed in a cylinder 6 formed in the cylinder block 5, and one end of an upper link 11 is swingably connected to the piston 1 via a piston pin 2. . The other end of the upper link 11 is rotatably connected to one end of the lower link 13 via an upper pin 12. The lower link 13 is swingably attached to the crankpin 4 of the crankshaft 3 at the center thereof. The piston 1 receives combustion pressure from a combustion chamber defined above. The crankshaft 3 is rotatably supported on the cylinder block 5 by a crank bearing bracket 7.

  One end of a control link 15 is rotatably connected to the other end of the lower link 13 via a control pin 14. The other end of the control link 15 is supported by a part of the internal combustion engine body so as to be swingable. In order to change the compression ratio, the swing support point 16 is supported by the support position variable means. Is displaceable. Specifically, as the support position varying means, a control shaft 18 extending in parallel with the crankshaft 3 and a circular eccentric cam 19 provided eccentrically to the control shaft 18 are provided. The other end of the control link 15 is rotatably fitted to the outer peripheral surface 19. The control shaft 18 is rotatably supported between the crank bearing bracket 7 and the control bearing bracket 8.

  Therefore, when the control shaft 18 is rotationally driven by an actuator (not shown) to change the compression ratio, the center position of the eccentric cam 19 serving as the swing fulcrum 16 of the control link 15 moves relative to the engine body. As a result, the motion restraint condition of the lower link 13 by the control link 15 changes, the stroke position of the piston 1 with respect to the crank angle changes, and consequently the engine compression ratio changes.

  2 to 5 show a first embodiment in which the present invention is applied to a pin connecting structure of the lower link 13 and the upper link 11 by the upper pin 12 described above, and FIG. 2 is a cross section taken along the line AA in FIG. FIG. 3 is a cross-sectional view taken along line III-III in FIG. 4 is a sectional view showing the first flange member alone, and FIG. 5 is a sectional view showing the second flange member alone. In this example, the lower link 13 corresponds to a first link member, the upper link 11 corresponds to a second link member, and the upper pin 12 corresponds to a connecting pin. Here, the lower link 13 corresponding to the first link member is restricted to have a relatively small dimension in the crankshaft direction in order to avoid interference with the counterweight 17 of the crankshaft 3.

  A first pin boss 22 and a second pin boss 23 are formed at one end of the lower link 13 so as to face each other in a bifurcated shape, a clevis shape, and a substantially U shape so that an upper link fitting groove 21 is formed in the center portion. ing. These first and second pin bosses 22 and 23 have a substantially constant thickness and extend in parallel to each other. And the 1st, 2nd pin bearing holes 24 and 25 which make a cylindrical surface are penetrated and formed in the 1st and 2nd pin bosses 22 and 23, respectively. The two pin bearing holes 24 and 25 are located on the same axis, and in the present embodiment, are formed to have the same diameter. The pin bosses 22 and 23 are arranged on the outer side of the lower link 13 so that the total length between both ends of the pin bosses 22 and 23 is secured within the range of the thickness of the lower link 13 (crank axis direction dimension). It is formed along the side.

  On the other hand, the end portion of the upper link 11 is configured as a third pin boss 26 having an axial dimension that can be fitted in the upper link fitting groove 21 with a very small gap. A third pin bearing hole 27 having a cylindrical surface is formed through. The diameter of the third pin bearing hole 27 is equal to the diameters of the first and second pin bearing holes 24 and 25 on the lower link 13 side.

  As shown in FIG. 3, the connecting pin 12 that is an upper pin that connects the lower link 13 and the upper link 11 has a simple cylindrical surface whose diameter does not change and is along its axis. The pin through-hole 37 is formed in a cylindrical shape. The outer diameter of the connecting pin 12 is substantially equal to the diameters of the first and second pin bearing holes 24 and 25 and the third pin bearing hole 27, and the connecting pin 12 has these pin bearing holes 24, 25 and 27. Penetrates and fits in a rotatable manner.

  In the pin connection structure of the present embodiment, a first flange member 40 and a second flange member 60 as a clip member, a washer member, and a large diameter member that are engaged with each other in the pin through hole 37 of the connection pin 12 are provided. Yes. The first flange member 40 includes a disc-shaped first flange 41 having a diameter larger than that of the first pin bearing hole 24 of the first pin boss 22, and the connecting pin 12 from the axial center portion / center portion of the first flange 41. And a first shaft portion 42 extending into the pin through-hole 37, and is integrally formed of a metal material (or a hard resin material). That is, the first flange member 40 includes a first shaft portion 42 that fits into the pin through hole 37 of the connecting pin 12 and a first flange 41 that is provided at one axial end of the first shaft portion 42. Has been. The second flange member 60 includes a disk-shaped second flange 61 having a larger diameter than the second pin bearing hole 25 of the second pin boss 23 and a second shaft portion extending from the second flange 61 into the pin through hole 37. 62, and is integrally formed of a metal material (or hard resin material). That is, the second flange member 60 includes a second shaft portion 62 that fits into the pin through-hole 37 and a second flange 61 that is provided at one end of the second shaft portion 62 in the axial direction. A circular recess 35 corresponding to the diameter of the flanges 41, 61 is provided on the outer surface of the lower link 13 so that the flanges 41, 61 do not protrude from the outer surface of the lower link 13. 61 is fitted.

  The distal end side of the first shaft portion 42 is used as an engaging portion that engages with each other in the pin through hole 37 so as to prevent the first flange member 40 and the second flange member 60 from being separated from each other in the axial direction. Further, a step surface facing the root side / first flange 41 side, that is, a first engagement surface 43 is formed, and the second shaft portion 62 has a step surface as a step surface facing the root side / second flange 61. Two engagement surfaces 63 are formed. In other words, the first engagement surface 43 as the first engagement portion formed in the first shaft portion 42 engages with the second shaft portion 62 in the pin through hole 37, so that the outer periphery of the first flange 41 The first flange member 40 is locked in the axial direction with respect to the first pin boss portion 22 of the first link member 13 with the portion facing the opening peripheral portion of the first pin bearing hole 24 substantially without a gap. . Similarly, when the second engagement surface 63 as the second engagement portion formed on the second shaft portion 62 engages with the first shaft portion 42 in the pin through hole 37, the outer periphery of the second flange 61 is The second flange member 60 is locked in the axial direction with respect to the second pin boss portion 23 of the first link member 40 with the portion facing the opening peripheral edge of the second pin bearing hole 25 substantially without a gap. . At the time of assembly, the connecting pin 12 is inserted into the pin bearing holes 24, 25, 27, and the first shaft portion 42 of the first flange member 40 and the second flange member 60 are inserted from both sides of the connecting pin 12. The biaxial portion 62 may be inserted and pushed into the pin through hole 37 of the connecting pin 12, and the first engagement surface 43 and the second engagement surface 63 may be engaged with each other and brought into surface contact with each other. Is extremely easy.

  The first shaft portion 42 includes a root portion 44 connected to the axial center portion of the first flange 41, a head portion 45 formed at the tip portion, and a neck portion 46 connecting the root portion and the head portion 45. The outer wall of the head 45 and the outer wall of the neck 46 are connected by the first engagement surface 43. The second shaft portion 62 has a cylindrical shape whose outer periphery forms a simple cylindrical surface, and the inner diameter of the large-diameter portion 64 on the base side connected to the center portion of the second flange 61 is smaller than the smaller diameter on the distal end side. The inner wall of the large diameter portion 64 and the inner wall of the small diameter portion 65 are connected by the second engagement surface 63.

  The outer diameter of the neck portion 46 is set to be equal to or smaller than the inner diameter of the small diameter portion 65, the outer diameter of the head portion 45 is set larger than the outer diameter of the small diameter portion 65, and the outer diameter of the large diameter portion 64 is the head 45. Is set larger than the outer diameter. At the time of assembly, the head 45 needs to pass through the small-diameter portion 65 with the deformation of the head 45 in the reduced diameter direction. In order to allow such deformation of the head portion 45 in the reduced diameter direction, the first shaft portion 42 is formed with a deformation groove 47 having a cross-shaped cross section and extending in the axial direction from the head portion 45 to the neck portion 46. . By the deformation groove 47, the first engagement surface 43 and the neck portion 46 are divided into four leg portions 47a. When the four leg portions 47a are inclined in the direction of approaching each other with the root portion 44 as a fulcrum, the head portion 45 is deformed in the reduced diameter direction.

  In order to improve the insertion workability of the first shaft portion 42 with respect to the second shaft portion 62, a substantially conical first tapered surface 48 tapering toward the distal end side is provided on the outer periphery of the head 45 of the first shaft portion 42. A substantially conical second tapered surface 68 is formed on the inner periphery of the small-diameter portion 65 of the second flange member 60. The second tapered surface 68 has a substantially conical shape that expands toward the tip of the opening.

  Accordingly, when the first shaft portion 42 of the first flange member 40 is pushed into the second shaft portion 62 of the second flange member 60 and combined, first, the first tapered surface 48 and the second shaft at the front end of the first shaft portion 42 are combined. The second tapered surface 68 at the tip of the portion 62 comes into contact. When the both 40 and 60 are further pushed toward each other from that state, the inclined surfaces of the two tapered surfaces 48 and 68 are in contact with each other, so that the head 45 of the first shaft portion 42 is moved from the pushing force in the axial direction. A component force is generated to press and deform in the reduced diameter direction. When the head portion 45 of the first shaft portion 42 is easily deformed by the component force in the radial direction, and the maximum outer diameter of the head portion 45 is equal to or smaller than the inner diameter of the small diameter portion 65 of the second shaft portion 62, the head portion 45 is It is pushed into the small diameter portion 65. When the head 45 passes through the small-diameter portion 65 and reaches the large-diameter portion 64, the head 45, which has been shrunk in the radial direction, automatically returns to its original state and expands in diameter due to its own elastic force, A state where the first engagement surface 43 and the second engagement surface 63 are in surface contact, that is, a geometrically coupled state is established.

  In the assembled state shown in FIG. 2, the first engagement surface 43 and the second engagement surface 63 are opposed to each other with no surface contact or substantially no gap, and the inner surfaces of the first flange 41 and the second flange 61 are connected to the connecting pin 12. The axial dimension of each part, more specifically, the axial dimension from the first flange 41 to the first engagement surface 43 and the second flange 61 to the second so as to face the both axial end surfaces of the first and second engagement surfaces 43 so as to face each other without substantial contact. The sum of the axial dimensions up to the two engaging surfaces 63 is set to be substantially equal to the axial dimension of the connecting pin 12. Accordingly, the first and second flange members 40 and 60 are positioned so as not to move or wobble in the axial direction with respect to the connecting pin 12.

  The first engagement surface 43 and the second engagement surface 63 are configured as conical tapered surfaces that taper toward the first flange 41 side. Therefore, the axial dimension error as described above can be effectively absorbed. However, the inclination angle of the first engagement surface 43 and the second engagement surface 63 with respect to the axis orthogonal plane is sufficiently small so that the head 45 does not inadvertently enter the small diameter portion 65 in the assembled state. For example, it is set sufficiently smaller than the inclination angle of the first tapered surface 48 of the head 45.

  The large diameter portion 64 is formed through the second flange 61 so that the first flange member 40 and the second flange member 60 can be separated and disassembled from each other at the time of disassembly or maintenance. One end of the large diameter portion 64 is open. When separating the first flange member 40 and the second flange member 60, a jig is inserted into the large-diameter portion 64 that opens to the second flange 61 side, and the first tapered surface at the tip of the first shaft portion 42 is inserted. 48 is pushed into the first flange 41 side (left direction in FIG. 2). This jig is formed of a cylinder whose outer diameter is smaller than the inner diameter of the large-diameter portion 64 and whose inner diameter is larger than the diameter of the head 45. By pushing the head 45 in the axial direction toward the first flange 41 with this jig, the first and second engaging surfaces 43 and 63 are inclined as described above. When a component force that contracts in the radial direction is applied and the outer diameter of the head 45 is deformed to be equal to or smaller than the inner diameter of the small-diameter portion 65, the head 45 enters the small-diameter portion 65 and continues to be pressed. Passing through 65, the first flange member 40 and the second flange member 60 are separated.

  In the assembled state, the axial positions of the first engaging surface 43 and the second engaging surface 63 that are engaged with each other are closer to the second flange 61 (to the right in FIG. 2) than the axial center of the connecting pin 12. The second flange 61 is disposed at a position close to the second flange 61. Further, the tip end of the second shaft portion 62 (small diameter portion 65) is disposed at a position close to the first flange 41 beyond the axial center portion of the connecting pin 12.

  Therefore, first, the head 45 is close to the second flange 61 where the large-diameter portion 64 is opened, and the length of the disassembling jig can be shortened, so that the disassembling work is facilitated.

  Second, since the axial lengths of the deformation grooves 47 and the legs 47a of the first shaft portion 42 can be sufficiently long, the head 45 can be easily deformed in the reduced diameter direction. The stress concentration at the base portion of the leg 47a due to deformation is alleviated, and the reliability and durability are improved.

  Third, the center of gravity in the state where both the flange members 40, 60 and the connecting pin 12 are combined can be brought close to the axial center of the connecting pin 12, and the load distribution can be made uniform in the axial direction. Lubricity and durability during high-speed engine operation can be improved. If the axial position of the first engagement surface 43 and the second engagement surface 63 is located closer to the first flange 41 than the axial center portion of the connecting pin, the large diameter portion 64 becomes longer, The center of gravity is greatly shifted to the first flange 41 side (left side in FIG. 2).

  In consideration of the insertion workability of the first shaft portion 42, the inner diameter of the small diameter portion 65 is set larger than the outer diameter of the neck portion 46, and in the assembled state, as shown in FIG. A slight gap 70 is secured between the neck 46 and the outer periphery. Accordingly, a so-called swinging motion in which both shaft portions 42 and 62 swing in the direction perpendicular to the axis with the contact portions of the engaging surfaces 43 and 63 as fulcrums is allowed. However, in the present embodiment, the engagement surfaces 43 and 63 are arranged at positions close to the second flange 61, and the axial dimension of the neck portion 46 and the small diameter portion 65 is sufficiently long, so that the small diameter through which the neck portion 46 is inserted. The span of the portion 65 becomes long, the movable range of the swing motion is sufficiently suppressed, and the swing motion that may cause vibration or the like can be effectively suppressed.

  According to the pin connection structure as described above, the connection pin 12 can rotate with respect to both the first and second pin bearing holes 24 and 25 on the lower link 13 side and the third pin bearing hole 27 on the upper link 11 side. Full floating type. As is apparent from FIG. 2, even if the connecting pin 12 tries to move in the axial direction, the flanges 41 and 61 come into contact with the bottom surface of the recess 35, and the movement is restricted. Therefore, although the connecting pin 12 can move in the axial direction by a minute amount with respect to both the lower link 13 and the upper link 11, it does not fall off in the axial direction. As described above, as a full floating type, both the lower link 13 and the upper link 11 are movable in both the circumferential direction and the axial direction, thereby suppressing local wear and seizure.

  Unlike such a structure using a snap ring as in the conventional example, it is not necessary to provide an extra pin boss or connecting pin area on the outer side in the axial direction of the flange members 40 and 60. The connecting pin 12 having a length substantially equal to the thickness (dimension in the crankshaft direction) of the link 13 can be used, and the entire first and second pin bearing holes 24 and 25 of the lower link 13 are in contact with the connecting pin 12. It can be effectively used as a surface (sliding surface). Therefore, it becomes easy to suppress the surface pressure of each part low within the limited thickness of the lower link 13. Conversely, there is no wasted area in the first and second pin bosses 22 and 23 on the lower link 13 side, and the weight and axial dimensions of the lower link 13 can be minimized.

  During operation of the internal combustion engine, since the connecting pin 12 and the upper link 11 and the lower link 13 rotate relatively, the flange members 40 and 60 are caused by the frictional force generated at the sliding contact portion between the flanges 41 and 61 and the bottom surface of the recess 35. There is a case where a torque is applied to rotate the pin with respect to the connecting pin 12. Accordingly, if the flange member is screwed into the connection pin or the flange member is fastened together with the connection pin using a screw member, the screw may be loosened depending on the torque input direction. On the other hand, in this embodiment, the engaging surfaces 43 and 63 of the flange members 40 and 60 are engaged and brought into surface contact with each other, and both the flanges 41 and 61 of the flange members 40 and 60 and the axially opposite end surfaces of the connecting pin 12 are used. Are opposed to each other and are in surface contact with each other, the axial movement of the flange members 40 and 60 with respect to the connecting pin 12 is restricted, and since no screws are used, there is no looseness of the screws, and reliability and durability. Also excellent.

  A second embodiment of the present invention will be described with reference to FIGS. The same constituent elements as those in the first embodiment are denoted by the same reference numerals, and redundant description will be omitted as appropriate.

  In the second embodiment, the flange members 40, 60 and the connecting pin 12 are fitted to each other so as to prevent the flange members 40, 60 and the connecting pin 12 from rotating relative to each other. The part is formed. As the fitting portion, the first flange member 40 is formed with a band-shaped first fitting protrusion 49 that extends in the axial direction from the inner surface of the first flange 41 and extends in the diameter direction. A belt-like first fitting groove 38 that is recessed in one end surface in the axial direction and extends in the diameter direction is formed. Further, the second flange member 60 is formed with a second band-like fitting protrusion 69 extending in the diametrical direction projecting from the inner surface of the second flange 61 in the axial direction. A band-shaped second fitting groove 39 that is recessed in the end surface and extends in the diameter direction is formed. When the first fitting protrusion 49 is fitted into the first fitting groove 38 with substantially no gap, the relative rotation between the first flange member 40 and the connecting pin 12 is prohibited and restrained, and the second fitting protrusion 69 is moved. By fitting in the second fitting groove 39 with substantially no gap, the relative rotation between the second flange member 60 and the connecting pin 12 is prohibited / restricted.

  According to the second embodiment, the relative rotation between the flange members 40, 60 and the connecting pin 12 is prevented, and the flange members 40, 60 and the connecting pin 12 rotate integrally. Wear due to relative rotation between the connection pin 12 and the connecting pin 12 is suppressed, and relative rotation between the first flange member 40 and the second flange member 60 is prevented. Can also be prevented. In particular, since the relative rotation between the first flange member 40 and the second flange member 60 is prevented, wear on the engaging surfaces 43 and 63 in surface contact with each other is avoided, and durability and reliability are improved.

  In the third to fifth embodiments described below, the first flange member and the second flange member have the same configuration. Therefore, only when distinguishing between the two, the configuration on the first flange member side is denoted by A after the reference symbol, and the configuration on the second flange member side is denoted by B after the reference symbol, and redundant description is provided. Omitted where appropriate.

  FIG. 9 is a sectional view showing a pin connection structure according to a third embodiment of the present invention. 10 is a front view (A), a side view (B), and a rear view (C) showing the flange member 80 of FIG. 9 alone, and FIG. 11 is a cross-sectional view taken along line XI-XI of FIG. is there. The connecting pin 12 is formed with a pin through hole 37 penetrating in the axial direction as a pin hole that opens at both axial end faces. Each flange member 80 is provided with a shaft portion 82 that fits into the pin through hole 37 and one axial end of the shaft portion 82, and has a larger diameter than the first pin bearing hole 24 and the second pin bearing hole 25. And a substantially disc-shaped flange 81. Further, a flange through hole 85 is formed in the flange member 80 across the shaft portion 82 and the flange 81. That is, the hole 85 is opened at the opening 86 on the flange 81 side. The shaft portion 82 is formed with a protruding portion (first and second engaging portions) 83 protruding outward in the radial direction at a tip portion opposite to the flange 81. The outer diameter of the projecting portion 83 is larger than the outer diameter of the general portion (neck portion) of the shaft portion 82 that connects the projecting portion 83 and the flange 81. That is, the protrusion 83 is partially enlarged in diameter relative to the shaft 82. The tip end portion of the shaft portion 82 on which the projection 83 is formed is processed so as to be folded inward, thereby forming a projecting piece portion 87 extending in the flange through hole 85 toward the flange 81 side. Further, the shaft portion 82 has three groove portions 84 extending in the axial direction intermittently formed in the circumferential direction. In other words, three leg portions extending in the axial direction are formed between the adjacent groove portions 84. ing. Therefore, the shaft portion 82 can be elastically deformed so as to approach the central axis with the root portion closer to the flange 81 as much as the groove portion 84, that is, elastically deformed in the diameter reducing direction.

  Each flange member 80 is integrally formed of a metal material, and can be easily processed and manufactured by the following method, for example. First, a disk-shaped metal material is deep-drawn to form a hollow shaft portion 82 and a flange 81. Next, while rotating the material, the protruding portion 87 is formed inside the hole 85 by rolling so that the tip end side of the shaft portion 82 is folded inward. At the same time, processing of the outer shape in the vicinity of the tip of the shaft portion 82 is also performed to form the protruding portion 83. Finally, the groove 84 is formed in three places by cutting.

  FIG. 12 is a sectional view showing the connecting pin 12 combined with the flange member 80 of this embodiment as a single unit. The connecting pin 12 has a substantially hollow cylindrical shape in which a pin through hole 37 extending in the axial direction is formed. The inner diameter of the general portion 73 of the pin bearing hole 37 is slightly larger than the outer diameter of the shaft portion 82 of the flange member 80 and smaller than the protrusion 83 at the tip of the shaft portion. The pin through-hole 37 is formed with a groove 71 that is recessed outward in the radial direction at the axial center. The groove portion 71 is formed in a ring shape over the entire length in the circumferential direction, and the inner diameter thereof is larger than the inner diameter of the general portion 73 of the pin through hole 37. Accordingly, stepped surfaces 72 that are bent radially outward from the pin through-holes 37 are formed at both axial ends of the groove 71. Further, at both ends in the axial direction of the pin through-hole 37, tapered portions 74 that are gradually reduced in diameter and tapered toward the central portion in the axial direction are formed.

  When the flange member 80 is pushed into the pin through-hole 37 of the connecting pin 12, the protruding portion 83 at the tip of the flange member 80 is pushed in the diameter reducing direction by the tapered portion 74, so that the shaft portion 82 including the protruding portion 83 is formed. The protrusion 83 is pushed into the pin through-hole 37 by being elastically deformed in the reduced diameter direction. In this state, when the flange member 80 is pushed to a position where the flange 81 substantially faces the end face of the connecting pin 12 with no gap, the projection 83 at the tip is reduced in the diameter reducing direction at the groove 71 where the inner diameter is widened. It is deformed in the diameter increasing direction so as to return to its original shape from the elastically deformed state. As a result, the protrusion 83 of the flange member 80 and the stepped surface 72 of the groove 71 of the connecting pin 12 face each other substantially without any gap, and the protrusion 83 and the groove 71 are in a geometrically engaged state. Thus, the flange member 80 is locked in the axial direction with respect to the connecting pin 12.

  In this way, by inserting and pushing the flange members 80A and 80B from both sides of the pin through-hole 37, the flange member can be assembled to the connecting pin 12, so that the assembly is extremely easy and the manufacturing cost is reduced. It can contribute greatly. In a state where the flange member is assembled, the flange 81 faces the axial end surfaces of the connecting pin 12 and the pin bosses 22 and 23 with substantially no gap, and the projection 83 has a substantially gap with the step surface 72 of the groove 71. Therefore, the flange member 80 is locked in the axial direction with respect to the connecting pin 12 and the axial movement of the connecting pin 12 with respect to the pin bosses 22 and 23 is prevented. Therefore, even if a thrust (axial) force acts on the flange member, it is ensured that the connecting pin 12 comes off the pin bosses 22 and 23 by the flange 81 coming into contact with the end face of the connecting pin 12. Can be prevented.

  Since the flange member 80 is assembled to the connecting pin 12 by the geometric engagement between the protrusion 83 and the groove 71, the connecting pin 12 and the flange member 80 are relatively rotatable. Therefore, during operation of the internal combustion engine with piston reciprocation, in addition to the thrust force as described above, a force in the rotational direction around the shaft can be applied to the flange member 80, so the flange member is temporarily connected using a screw. Although there is a risk of loosening due to the force in the above rotation direction when assembled to the pin, in this embodiment, since the connecting pin and the flange member can be rotated relative to each other, there is no such problem, and reliability and durability. Is excellent.

  When disassembling the pin connection structure for maintenance or replacement reasons, a round bar-shaped special tool is inserted from the opening 86. The tip of the special tool has an inner hollow taper shape. Therefore, when the special tool is pushed into the hole 85, the taper surface of the tool and the projecting piece portion 87 come into contact with each other, and the projecting piece portion 87 is pushed inward in the radial direction by this taper surface, and the shaft portion 82 of the flange member 80 is moved. It is elastically deformed in the reduced diameter direction, and the engagement state between the protrusion 83 at the tip and the stepped surface 72 on the pin side is eliminated. In this state, the flange member 80 may be extracted from the connecting pin 12 with a special tool.

  FIG. 13 is a front view (A), a sectional view (B), and a rear view (C) showing a flange member 90 according to a fourth embodiment of the present invention. Each flange member 90 is provided with a collar-shaped shaft portion 92 having a relatively short hollow cylindrical shape, and one end in the axial direction of the shaft portion 92, and has an outer diameter larger than the inner diameter of the bearing hole and serves as a retaining function. A disc-shaped flange 91. A protrusion 93 is formed in the vicinity of the end surface of the shaft portion 92 opposite to the flange 91. The flange member 90 has a notch 98 which is a part in the circumferential direction removed, and is substantially C-shaped when viewed in the axial direction. Small holes 99 are formed on both sides of the flange 91 near the notch 98. By inserting the tip end portion of the snap ring plier as a flange member extraction tool into these small holes 99 and shrinking it, the entire flange member 90 can be elastically deformed so as to shrink in the diameter reducing direction. By reducing the diameter of the flange member 90 as a whole by this elastic deformation, the outer diameter of the protrusion 93 can be smaller than the outer diameter of the shaft 92 before the deformation. An auxiliary notch 94 is also formed in a portion symmetrical to the notch 98 with respect to the center axis of the flange member 90. The auxiliary notch 94 reduces the rigidity of the flange member 90 and facilitates elastic deformation in the diameter reducing direction so as to close the notch 98.

  Similarly to the third embodiment, the flange member 90 of the present embodiment is also integrally formed of a metal material, and can be easily processed and manufactured by the following method, for example. First, a disk-shaped metal material is pressed to remove the circumferential notch 98 and auxiliary notch 94, and at the same time, the central part is machined into a concave shape to form the shaft 92. Next, the projecting portion 93 may be formed by bending the end portion of the shaft portion 92 while rotating the material while the center of the shaft portion 92 is fixed to the jig.

  FIG. 14 is a sectional view showing the connecting pin 12 combined with the flange member 90 of the fourth embodiment alone. A pin through hole 37 concentric with the outer periphery of the pin is formed through the connecting pin 12 in the axial direction. In this embodiment, the pin through hole 37 is partially reduced in diameter in the axial central portion 101. The outer diameter of the shaft portion 92 of the flange member 90 is slightly smaller than the pin through hole 37. A groove portion 102 having a partially enlarged diameter is formed on the inner peripheral surface of the pin through hole 37. The flange member 90 is held with respect to the connecting pin 12 by fitting the groove portion 102 and the projection portion 93 of the flange member 90 to form a geometrically engaged state. A tapered portion 103 is formed at the mouth of the pin through hole 37 on the pin end surface side. When the flange member 90 is assembled to the connecting pin 12, if the flange member 90 is pushed into the pin through hole 37 of the connecting pin 12, the protruding portion 93 is pressed in the diameter-reducing direction by the taper portion 103. Thus, without deforming the flange member 90 in the radial direction, the shaft portion 92 including the protruding portion 93 is elastically deformed in the reduced diameter direction, and the protruding portion 93 is pushed into the pin through-hole 37. In this state, when the flange member 90 is further pushed in, the projecting portion 93 is fitted into the groove portion 102 and the flange member 90 is automatically assembled to the connecting pin 12. In the fourth embodiment, the same operational effects as in the third embodiment can be obtained.

  FIG. 15: is the front view (A), sectional drawing (B), and rear view (C) which show the flange member 90 which concerns on 5th Example. The basic configuration, the manufacturing method, the engagement method with the connecting pin, and the like are the same as in the case of the fourth embodiment, and redundant description is omitted. In the fifth embodiment, instead of the auxiliary notch portion 94 in the fourth embodiment, the auxiliary notch portion 95 and the flange through hole 96 are positioned at an angular position symmetrical to the notch portion 98 with respect to the central axis of the flange member 90. It is formed to be continuous. That is, the auxiliary notch portion 95 is notched so as to project radially outward from a flange through hole 96 penetratingly formed from the shaft portion 92 to the flange 91. Therefore, as in the fourth embodiment, when the flange member 90 is deformed in the diameter reducing direction so that the notch 98 is contracted, the flange 91 near the auxiliary notch 95 is deformed, so that the flange member 90 is contracted. The deformation in the radial direction is facilitated.

  As described above, the present invention has been described based on the specific embodiments. However, the present invention is not limited to the above-described embodiments, and includes various modifications and changes without departing from the spirit of the present invention. . For example, contrary to the above embodiment, the pin boss of the upper link may have a bifurcated shape sandwiching the pin boss of the lower link. Moreover, you may apply this invention to the pin connection structure of the piston pin of FIG. 1, or a control pin. Furthermore, the present invention may be applied to a piston pin connecting structure of a piston and a connecting rod in a single link type piston-crank mechanism.

  The technical ideas of the present invention that can be grasped from the above embodiments are listed together with their effects.

  (1) In a state where the third bearing hole formed in the second link member is coaxially disposed between the first bearing hole and the second bearing hole formed in the first link member, these first to first A pin coupling structure of a link mechanism that rotatably couples the first link member and the second link member by fitting a coupling pin into the third bearing hole, and opens to the axial end surface of the coupling pin. A first flange member having a first shaft portion that fits into the pin hole, and a first flange that is provided at one axial end of the first shaft portion and has a larger diameter than the first pin bearing hole; A second shaft portion that fits into a pin hole that opens in the axial end surface of the connecting pin, and a second flange that is provided at one end in the axial direction of the second shaft portion and has a larger diameter than the second pin bearing hole And a second flange member having a first engagement portion provided on the first shaft portion as a pin. By engaging the second shaft portion or the connecting pin within the first flange member with respect to the connecting pin, the first flange faces the opening peripheral portion of the first pin bearing hole substantially without a gap. When the second engaging portion provided in the second shaft portion engages with the first shaft portion or the connecting pin within the pin hole, the second flange is connected to the second pin bearing. The second flange member is locked in the axial direction with respect to the connecting pin in a state of facing the opening peripheral edge of the hole substantially without a gap.

  That is, the first flange member and the second flange member are engaged with the first flange member and the second flange member in the axial direction with respect to the connecting pin, thereby the first flange of the first flange member. And a second flange of the second flange member, the connecting pin is pinched and the connecting pin is prevented from falling off the pin boss. Unlike the pin connection structure using a snap ring, there is no need for an extra pin boss or connection pin area outside the flange member in the axial direction, ensuring the contact area between the pin boss and the connection pin, and reducing the size and weight of the pin boss. Can be achieved at a high level. Since the first flange member and the second flange member are attached to the connecting pin without using a screw element, the flange member and the connecting pin do not fall off due to loosening of the screw, and the durability and reliability are excellent. Yes.

  (2) Each said flange member is integrally formed with the metal material excellent in intensity | strength and rigidity. Therefore, the flange member is excellent in strength and rigidity, and the number of parts is minimized.

  (3) Each of the shaft portions has a hollow shape that can be deformed in the radial direction, and when the shaft portion is pushed into the pin hole, the engaging portion is engaged through elastic deformation in the radial direction. Yes. Therefore, when assembling, the flange member can be assembled to the connecting pin by pushing the shaft portion of each flange member into the pin hole. In other words, the assembly work is completed simply by pushing the shaft portion of the flange member into the pin hole of the connecting pin, and the work such as screw tightening and holding the snap ring is unnecessary, so the assembly work is extremely easy. is there.

  (4) The link mechanism has a lower link rotatably attached to a crankpin of the crankshaft, an upper link that links the lower link and the piston, and an upper pin that rotatably connects the lower link and the upper link. And a multi-link type piston-crank mechanism for an internal combustion engine, wherein the upper pin is the connecting pin. In such a multi-link type piston-crank mechanism, the pin connection structure of the present invention is extremely effective because the arrangement space for the pin connection structure, particularly the dimension in the pin axial direction, is severe.

  (5) A lower link in which the link mechanism is rotatably attached to a crankpin of a crankshaft, an upper link that links the lower link and the piston, and an upper pin that rotatably connects the lower link and the upper link. And a control link that links the lower link and the engine body, a control pin that rotatably connects the lower link and the control link, and a support position of the control link on the engine body side by changing the engine compression ratio. A variable compression ratio mechanism for an internal combustion engine having a support position changing means to be changed, wherein at least one of the upper pin and the control pin is the connecting pin. In such a variable compression ratio mechanism, the pin connection structure of the present invention is extremely effective because the arrangement space for the pin connection structure, particularly the size in the pin axis direction, is severely limited.

  (6) The pin hole is a pin through hole penetrating the inside of the connecting pin in the axial direction, and the first engaging portion and the second engaging portion engage with each other in the pin through hole. When the first engagement portion and the second engagement portion engage with each other, the first flange member and the second flange member are prevented from moving away from each other. The connecting pin is pinched between the first flange and the second flange of the second flange member, and the connecting pin is prevented from falling off the pin boss.

  (7) The first shaft portion connects the root portion connected to the central portion of the first flange, the head portion that can be deformed in the diameter-reducing direction, and the root portion and the head portion. A neck portion having a small outer diameter, and the second shaft portion connects a cylindrical small diameter portion and the small diameter portion and the central portion of the second flange, and has a cylindrical shape having a larger inner diameter than the small diameter portion. The first engagement portion is a first engagement surface as a step surface between the outer wall of the neck portion and the outer wall of the head portion, and the second engagement portion is A second engaging surface as a step surface between the inner wall of the small diameter portion and the inner wall of the large diameter portion, wherein the outer diameter of the neck portion is equal to or smaller than the inner diameter of the small diameter portion, and the outer diameter of the head portion is larger than the inner diameter of the small diameter portion large.

  By pushing the first shaft portion of the first flange member axially into the second shaft portion of the second flange member, the head passes through the small diameter portion with deformation in the reduced diameter direction and reaches the large diameter portion, By expanding and restoring the diameter of the head to the original shape, the first engagement surface and the second engagement surface are brought into an engagement state in which they face each other and come into surface contact with each other. In this way, both can be fitted together simply by pushing the flange member in the axial direction, and assembly work is easy.

  (8) A first tapered surface that is tapered in a conical shape toward the tip is formed on the outer periphery of the head. During assembly, when the head is pushed axially into the cylindrical second shaft, the first tapered surface comes into contact with the inner periphery of the tip of the second shaft and presses the head in the diameter-reducing direction. Since the component force acts and the deformation of the head in the diameter reducing direction is promoted, the assembling workability is improved.

  (9) The 2nd taper surface which diameter-expands conically toward the front-end | tip is formed in the inner periphery of the said small diameter part. When assembling, when the head is pushed axially into the inside of the small diameter portion of the cylindrical second shaft portion, the outer periphery of the head contacts the second tapered surface, and the component force that presses the head in the reduced diameter direction Acts to promote the deformation of the head in the diameter reducing direction, so that the assembly workability is improved.

  (10) A deformation groove that allows deformation in the reduced diameter direction of the head portion is formed in the neck portion and the head portion so as to extend in the axial direction, and the large diameter portion is formed through the second flange. In addition, the first engagement surface and the second engagement surface are disposed closer to the second flange than the axial center of the connection pin.

  Since the large-diameter portion is formed through the second flange, a jig is inserted into the large-diameter portion from the second flange side during disassembly and maintenance, and the head is pushed into the first flange side by this jig. It becomes possible to isolate | separate a 1st flange and a 2nd flange. Since the first engagement surface and the second engagement surface are arranged closer to the second flange, the jig insertion length is shortened during the above-described disassembly / maintenance, and disassembly work is facilitated.

  In addition, since the first engagement surface and the second engagement surface are disposed closer to the second flange, the axial dimension of the neck portion and the deformation groove can be secured relatively long. Accordingly, the pushing force required for elastic deformation of the head by the deformation groove is suppressed to be relatively small, and the assembly workability is improved, and the stress concentrated on the root portion of the deformation groove due to the deformation is effectively reduced. Can do.

  Furthermore, since the first engagement surface and the second engagement surface are arranged closer to the second flange, compared to the case where the first engagement surface and the second engagement surface are arranged closer to the first flange, The center of gravity in a state where the connecting pin and the first and second flange members are combined can be brought closer to the axial center of the connecting pin, and the weight balance is improved.

  (11) The tip of the second shaft portion extends to a position closer to the first flange than the axial center of the connecting pin.

  As a result, the axial dimension of the small diameter portion, the neck portion, and the deformation groove can be secured sufficiently long, and the length of the neck portion supported by the gap fit in the small diameter portion is increased. Therefore, the range in which the neck can swing or swing in the small diameter portion with the engaging portion as a fulcrum during actual movement is narrowed, and this swinging motion can be sufficiently suppressed. Since the swing motion is suppressed in this way, wear at the engaging portion or the like is reduced, and durability and reliability are improved.

  (12) A rotation stopping means for preventing relative rotation between the first flange member and the second flange member and the connecting pin is provided. Thus, by preventing the relative rotation between the first and second flange members and the connecting pin, the relative rotation between the first flange member and the second flange member is also prevented, and the contact portion including the engaging portion described above is used. Wear due to friction is reduced and avoided, and reliability and durability are improved.

  (13) Each of the engaging portions is a protruding portion that protrudes radially outward from the tip of the shaft portion, and the protruding portion fits into a groove formed on the inner peripheral surface of the pin hole. In this way, the protrusion is fitted into the groove in the pin hole, so that the flange member is held in an axially locked state with respect to the connecting pin.

  (14) A tapered surface that tapers toward the center of the connecting pin is formed in the opening of the pin hole. In this case, by pushing the shaft part into the opening of the pin hole, the projecting part comes into contact with the tapered surface, and the shaft part including the projecting part is pressed by the tapered surface in the diameter-reducing direction, so that the projecting part is The included shaft portion is elastically deformed in the direction of diameter reduction and is fitted into the pin hole. That is, the flange member can be assembled to the connecting pin by substantially pushing the shaft portion into the pin hole.

  (15) The shaft portion has a substantially cylindrical shape and a plurality of grooves extending in the axial direction so as to allow elastic deformation in the reduced diameter direction.

  (16) A flange through hole extending in the axial direction through the shaft portion and the flange is formed, and a projecting piece portion extending toward the flange side in the flange through hole is formed at the tip of the shaft portion. ing. When disassembling the link connecting structure by the connecting pin, an appropriate tool is brought into contact with the projecting piece through the flange through hole, the shaft is elastically deformed in the diameter reducing direction, and the flange member is pulled out from the connecting pin. good.

  (17) The flange member is substantially C-shaped when viewed in the axial direction having a notch in a part of the circumferential direction so as to allow elastic deformation in the reduced diameter direction. Therefore, when disassembling the link connection structure using the connection pins, the flange member can be elastically deformed in the reduced diameter direction so as to eliminate the notch.

  (18) The flange is formed with an auxiliary notch at an axially symmetric portion with respect to the notch. This auxiliary notch facilitates elastic deformation of the flange in the reduced diameter direction.

  (19) The auxiliary notch is formed continuously with a flange through hole formed through the shaft and the flange.

The principal part sectional drawing of the internal combustion engine which shows the variable compression ratio mechanism as a double link type piston-crank mechanism in which the pin connection structure concerning this invention was used. Sectional drawing which follows the AA line of FIG. 1 which shows the pin connection structure of 1st Example. Sectional drawing which follows the III-III line of FIG. 2 which shows the pin connection structure of 1st Example. Sectional drawing which shows the 1st flange member of 1st Example alone. Sectional drawing which shows the 2nd flange member of 1st Example alone. Sectional drawing which follows the AA line of FIG. 1 which shows the pin connection structure of 2nd Example. Sectional drawing which follows the VII-VII line of FIG. 6 which shows the pin connection structure of 2nd Example. Sectional drawing which follows the VIII-VIII line of FIG. 6 which shows the pin connection structure of 2nd Example. Sectional drawing which follows the AA line of FIG. 1 which shows the pin connection structure of 3rd Example. The front view (A), side view (B), and back view (C) which show the flange member of FIG. 9 alone. Sectional drawing which follows the XI-XI line | wire of FIG. Sectional drawing which shows the connection pin which concerns on 3rd Example alone. The front view (A), sectional view (B), and back view (C) which show the flange member concerning the 4th example alone. Sectional drawing which shows the connection pin of 4th Example alone. The front view (A), sectional view (B), and rear view (C) which show the flange member concerning a 5th example alone.

Explanation of symbols

11 ... Upper link (second link member)
12 ... Upper pin (connection pin)
13 ... Lower link (first link member)
22 ... 1st pin boss 23 ... 2nd pin boss 24 ... 1st bearing hole 25 ... 2nd bearing hole 26 ... 3rd pin boss 27 ... 3rd bearing hole 40 ... 1st flange member 41 ... 1st flange 42 ... 1st axial part DESCRIPTION OF SYMBOLS 43 ... 1st engagement surface 44 ... Base part 45 ... Head part 46 ... Neck part 47 ... Groove for deformation 48 ... 1st taper surface 60 ... 2nd flange member 61 ... 2nd flange 62 ... 2nd axial part 63 ... 2nd Engagement surface 64 ... Large diameter portion 65 ... Small diameter portion 68 ... Second taper surface 80, 90 ... Flange member 81, 91 ... Flange 82, 92 ... Shaft portion 83, 93 ... Projection portion

Claims (19)

In a state where the third bearing hole formed in the second link member is coaxially disposed between the first bearing hole and the second bearing hole formed in the first link member, these first to third bearings A pin coupling structure of a link mechanism that rotatably couples the first link member and the second link member by fitting a coupling pin into the hole,
A first shaft portion that fits into a pin hole that opens in the axial end surface of the connecting pin, and a first flange that is provided at one axial end of the first shaft portion and has a larger diameter than the first pin bearing hole And a first flange member having
A second shaft portion that fits into a pin hole that opens in the axial end surface of the connecting pin, and a second flange that is provided at one end in the axial direction of the second shaft portion and has a larger diameter than the second pin bearing hole And a second flange member having
The first engaging portion provided in the first shaft portion engages with the second shaft portion or the connecting pin in the pin hole, so that the first flange is substantially at the opening peripheral portion of the first pin bearing hole. The first flange member is locked in the axial direction with respect to the connecting pin in a state of facing the gap without any gap,
The second engaging portion provided on the second shaft portion engages with the first shaft portion or the connecting pin in the pin hole, so that the second flange is substantially at the opening peripheral edge portion of the second pin bearing hole. A pin coupling structure of a link mechanism in which the second flange member is locked in the axial direction with respect to the coupling pin in a state where the second flange member is opposed to the coupling pin.   The pin connection structure for a link mechanism according to claim 1, wherein the flange members are integrally formed of a metal material.   Each of the shaft portions has a hollow shape that can be deformed in the radial direction, and the engaging portion is configured to be engaged through elastic deformation in the radial direction by pushing the shaft portion into the pin hole. The pin connection structure of the link mechanism according to 3. The link mechanism includes a lower link rotatably attached to a crankpin of a crankshaft, an upper link that links the lower link and the piston, and an upper pin that rotatably connects the lower link and the upper link. A multi-link piston-crank mechanism for an internal combustion engine,
The pin connection structure for a link mechanism according to any one of claims 1 to 3, wherein the upper pin is the connection pin. The link mechanism includes a lower link rotatably attached to a crankpin of the crankshaft, an upper link that links the lower link and the piston, an upper pin that rotatably connects the lower link and the upper link, and a lower link A control link that links the link and the engine main body, a control pin that rotatably connects the lower link and the control link, and a support that changes the engine compression ratio by changing the support position of the control link on the engine main body side. A variable compression ratio mechanism for an internal combustion engine having position variable means,
The pin connection structure for a link mechanism according to any one of claims 1 to 3, wherein at least one of the upper pin and the control pin is the connection pin. The pin hole is a pin through hole penetrating the inside of the connecting pin in the axial direction,
The pin connection structure for a link mechanism according to any one of claims 1 to 5, wherein the first engagement portion and the second engagement portion engage with each other within the pin through hole. The first shaft portion connects a root portion connected to the central portion of the first flange, a head portion that can be deformed in a reduced diameter direction, the root portion and the head portion, and has an outer diameter that is larger than that of the head portion. A small neck, and
The second shaft portion has a cylindrical small-diameter portion, a cylindrical large-diameter portion that connects the small-diameter portion and the central portion of the second flange, and has a larger inner diameter than the small-diameter portion,
The first engagement portion is a first engagement surface as a step surface between the outer wall of the neck and the outer wall of the head;
The second engagement portion is a second engagement surface as a step surface between the inner wall of the small diameter portion and the inner wall of the large diameter portion,
The pin connection structure for a link mechanism according to claim 6, wherein an outer diameter of the neck portion is equal to or smaller than an inner diameter of the small diameter portion, and an outer diameter of the head portion is larger than an inner diameter of the small diameter portion.   The pin connection structure of the link mechanism according to claim 7, wherein a first taper surface tapered in a conical shape toward the tip is formed on an outer periphery of the head.   The pin connection structure of the link mechanism according to claim 7 or 8, wherein a second taper surface that is conically enlarged toward the tip is formed on an inner periphery of the small diameter portion. In the neck and the head, a deformation groove that allows deformation in the reduced diameter direction of the head is formed to extend in the axial direction,
The large diameter portion is formed through the second flange,
The pin of the link mechanism according to any one of claims 7 to 9, wherein the first engagement surface and the second engagement surface are disposed closer to the second flange than an axial center of the connection pin. Connected structure.   The pin connection structure for a link mechanism according to claim 10, wherein a tip end of the second shaft portion extends to a position closer to the first flange than an axial center of the connection pin. The pin connection structure for a link mechanism according to any one of claims 6 to 11, further comprising a rotation stop means for preventing relative rotation between the first flange member and the second flange member and the connection pin.   Each said engaging part is a projection part which protruded to radial direction outward from the front-end | tip of the axial part, This projection part fits into the groove part formed in the internal peripheral surface of the said pin hole. The pin connection structure of the link mechanism in any one of.   The pin connection structure of the link mechanism according to claim 13, wherein a tapered surface that tapers toward a central portion of the connection pin is formed in the opening of the pin hole.   The pin connection structure for a link mechanism according to claim 13 or 14, wherein the shaft portion has a substantially cylindrical shape and a plurality of grooves extending in the axial direction so as to allow elastic deformation in the reduced diameter direction.   A flange through-hole that extends in the axial direction through the shaft and the flange is formed, and a projecting piece that extends toward the flange in the flange through-hole is formed at the tip of the shaft. Item 16. A pin coupling structure for a link mechanism according to Item 15.   The pin of the link mechanism according to claim 13 or 14, wherein the flange member has a substantially C shape when viewed in the axial direction and has a notch in a part of the circumferential direction so as to allow elastic deformation in the reduced diameter direction. Connected structure.   The pin connection structure for a link mechanism according to claim 17, wherein an auxiliary notch portion is formed in the flange at an axially symmetric portion with respect to the notch portion. The pin connection structure for a link mechanism according to claim 18, wherein the auxiliary notch portion is formed continuously with a flange through hole formed through the shaft portion and the flange.

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