JP4269810B2 - Link mechanism pin connection structure - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
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.
[0002]
[Prior art]
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.
[0003]
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.
[0004]
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.
[0005]
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.
[0006]
[Patent Document 1]
JP 2000-18383 A
[0007]
[Patent Document 2]
JP 2001-227367 A
[0008]
[Patent Document 3]
JP 2002-61501 A
[0009]
[Problems to be solved by the invention]
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.
[0010]
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 engine longitudinal direction.
[0011]
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 when the snap ring is fitted in the ring groove of the connecting pin, the assembly work is similarly complicated.
[0012]
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 with excellent properties.
[0013]
[Means for Solving the Problems]
The link mechanism according to the present invention includes a first link member having a first pin boss and a second pin boss disposed so as to face each other in a bifurcated manner, and a third pin boss disposed between the first pin boss and the second pin boss. The first link member and the second link member are rotatably connected through the second link member and the first to third pin bearing holes formed in the first to third pin bosses, respectively. And a connecting pin. The pin connection structure of the present invention has a first large diameter member having a larger diameter than the first pin bearing hole of the first pin boss and a second large diameter having a larger diameter than the second pin bearing hole of the second pin boss. The diameter member and the first large-diameter member are fixed to one end in the axial direction of the connecting pin, and the second large-diameter member is fixed to the other end in the axial direction of the connecting pin. Screw member And each large-diameter member and the coupling pin have a fitting portion in which the large-diameter member and the coupling pin are fitted to each other so as to prevent relative rotation about the axis.
[0014]
【The invention's effect】
The large-diameter member fixed on both axial sides of the connecting pin prevents the connecting pin from falling off in the axial direction. Since there is no need to secure an extra pin boss or connecting pin area outside the large-diameter member in the axial direction, the contact area between the pin boss and the connecting pin can be secured and the pin boss can be made smaller and lighter at a high level. can do. When assembling, fixing bolts etc. Screw member Therefore, the large-diameter member may be fixed to both sides in the axial direction of the connecting pin, and the assembling work is easy as compared with the pin connecting structure using the snap ring described above. Furthermore, it is a separate member from the large-diameter member. Screw member Therefore, since the large-diameter member is fixed to the connecting pin, for example, the durability and reliability of the fixing portion are excellent as compared with the case where the large-diameter member is directly fixed to the connecting pin.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.
[0016]
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.
[0017]
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.
[0018]
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.
[0019]
2 to 5 show a first embodiment in which the present invention is applied to the pin connection structure of the lower link 13 and the upper link 11 by the upper pin 12, and FIG. 2 is a cross-sectional view along the line AA. FIG. 3 is an exploded sectional view. 4 is a front view (a), a sectional view (b), and a rear view (c) showing a large-diameter member alone, and FIG. 5 is a front view (a) and a sectional view showing an upper pin as a connecting pin alone. FIG. 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.
[0020]
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.
[0021]
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.
[0022]
As shown in FIG. 5, the connecting pin 12, which is an upper pin that connects the lower link 13 and the upper link 11, is formed in a cylindrical shape whose outer peripheral surface forms a simple cylindrical surface with no diameter change. The diameter of the connecting pin 12 is substantially equal to the diameters of the first and second pin bearing holes 24, 25 and the third pin bearing hole 27, and the connecting pin 12 extends to these pin bearing holes 24, 25, 27. On the other hand, it penetrates and fits in a rotatable manner.
[0023]
A first large-diameter member 31A as a first large-diameter member is fastened and fixed to one end of the connecting pin 12 in the axial direction by a first fixing bolt 36A, and a second large-diameter member is connected to the other end of the connecting pin 12 in the axial direction. A second large-diameter member 31B as a member is fastened and fixed together by a second fixing bolt 36B. A pin through hole 37 is formed in the connecting pin 12 along the axial center, and a female screw 38 into which a male screw formed at the tip of each fixing bolt 36 (36A, 36B) is screwed to both ends of the through hole 37. Is formed. In each large diameter member 31 (31A, 31B), a flange through hole 39 through which each fixing bolt 36 passes is formed along the axis.
[0024]
At the time of assembly, the connecting pin 12 is inserted into the pin bearing holes 24, 25, 27, and the fixing bolt 36 is screwed into the female screw 38 of the connecting pin 12 through the flange through hole 39 of the large-diameter member 31. . Alternatively, one of the large-diameter members 31A and 31B is fixed to the connecting pin 12 in advance, and after the lower link 13 and the upper link 11 are combined, the other of the large-diameter members 31A and 31B is finally fixed to the connecting pin 12. Such an assembly procedure is also possible. As described above, the large-diameter member 31 is arranged at both ends of the connecting pin 12 and then the fixing bolt 36 is tightened, and the assembly is possible as compared with the pin connecting structure using the snap ring described above. Work is very easy.
[0025]
Each large-diameter member 31 is formed so as to protrude in an axial direction from an annular washer portion, that is, a flange 32 having an outer diameter larger than the diameter of the pin bearing holes 24, 25, 27, and an axial center portion of the flange 32. And a fitting protrusion 33. A fitting hole 34 into which the fitting projection 33 is fitted is recessed at both ends of the connecting pin 12. The fitting protrusion 33 and the fitting hole 34 function as a fitting portion for preventing rotation that prevents and restrains the large-diameter member 31 and the connecting pin 12 from rotating about the axis by fitting each other. ing. Specifically, the outer periphery of the fitting protrusion 33 and the inner periphery of the fitting hole 34 that are fitted to each other are non-circular, polygonal, and rectangular, and in this embodiment are set to regular hexagonal shapes. Has been. That is, the fitting protrusion 33 has a regular hexagonal column shape along the axis of the large-diameter member 31.
[0026]
A circular recess 35 corresponding to the diameter of the flange 32 is provided on the outer surface of the lower link 13 so that each large-diameter member 31 does not protrude from the outer surface of the lower link 13. Mating.
[0027]
The axial distance between the flanges 32 of the pair of large diameter members 31, that is, the axial length of the connection pins 12, so that the large diameter member 31 fixed to the connection pin 12 can smoothly rotate with respect to the lower link 13. Is given slightly larger than the interval between the bottom surfaces of the pair of recesses 35. In other words, in the mounted state, a slight gap is formed between the bottom surface of the recess 35 and the flange 32 in the axial direction. Since the size of the gap depends only on the dimensions of the two members, that is, the axial length of the connecting pin 12 and the distance between the bottom surfaces of the pair of recesses 35, accuracy control is easy.
[0028]
Each fixing bolt 36 is a countersunk head bolt including a countersunk head 40 having a flat upper surface (top surface) and a conical surface. Correspondingly, a dish pad 50 having an inverted conical inclined surface is recessed in the opening peripheral edge of the flange through hole 39 of the large-diameter member 31 on which the seat surface of the dish head 40 is seated. With such a countersunk head 40 and countersink 50, the large-diameter member 31 can be firmly fixed to the connecting pin 12 by a strong axial compression force, and the end face of the bolt 36 is adjusted to have a large diameter by adjusting the screwing of the bolt 36. The side surfaces of the member 31 and the pin bosses 22 and 23 can be relatively easily aligned on the same plane. For example, a minus-shaped groove (not shown) is formed on the top surface of the countersunk head 40, and a screw driver is inserted into the groove to perform a screwing operation.
[0029]
According to such a pin connection structure, the connection pin 12 is fully rotatable 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. Floating form. As is apparent from FIG. 2, even when the connecting pin 12 is about to move in the axial direction, the flange 32 comes 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.
[0030]
Unlike the structure using a snap ring as in the conventional example, it is not necessary to provide an extra pin boss or connecting pin area outside the large-diameter member 31 in the axial direction, although it is such a full floating type. The connecting pin 12 having a length substantially equal to the thickness of 13 (crank axis direction dimension) 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 used effectively as a (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.
[0031]
During operation of the internal combustion engine, the connecting pin 12 and the upper link 11 and the lower link 13 rotate relatively, so that the large-diameter member 31 is connected to the connecting pin by the frictional force generated at the sliding contact portion between the flange 32 and the bottom surface of the recess 35. The torque which tries to rotate with respect to 12 may act. Accordingly, if a male screw is formed on the large-diameter member and the large-diameter member is directly screwed into the connecting pin, the screw may be loosened depending on the torque input direction. On the other hand, in the present embodiment, the large-diameter member 31 is reliably prevented and restrained from rotating relative to the connecting pin 12 by the fitting protrusion 33 and the fitting hole 34 that are mechanically fitted to each other. In addition, since the large-diameter member 31 is fastened and fixed to the connecting pin 12 by a fixing bolt 36, which is a separate member from the large-diameter member 31, torque in the rotational direction acts on the flange 32 temporarily. However, there is no risk of loosening the screw, and it is excellent in reliability and durability.
[0032]
In the second to fourth embodiments described below, the same reference numerals are assigned to substantially the same parts as those of the above-described embodiments, and a duplicate description is omitted as appropriate.
[0033]
6 and 7 show a pin connection structure according to a second embodiment of the present invention. FIG. 6 is a cross-sectional view along line AA in FIG. 1, and FIG. 7 is an exploded cross-sectional view. The basic configuration is substantially the same as that of the first embodiment, but here, in particular, the female screw (38) is not formed at both ends of the through hole 37 of the connecting pin 12, and the fixing bolt 36 of the first embodiment is provided. Instead, it differs from the first embodiment in that the male screw member 41 and the female screw member 42 are used.
[0034]
The male screw member 41 has the countersunk head 40 having a flat top surface and a conical surface, and a male screw 43 is formed on the outer periphery of the tip. The female screw member 42 has the countersunk head 40 having a flat top surface and a conical surface, and a female screw 44 is formed on the inner periphery of the screw hole at the tip. At the time of assembly, the male screw member 41 is inserted into the pin through hole 37 of the connecting pin 12 through the flange through hole 39 of the first large diameter member 31A, and the female screw member 42 is inserted into the flange through hole of the second large diameter member 31B. 39 is inserted into the pin through hole 37, and the male screw 43 of the male screw member 41 is screwed into the female screw 44 of the female screw member 42 inside the pin through hole 37, whereby both large-diameter members 31A and 31B are connected to the connecting pin. 12 is fastened to both ends.
[0035]
According to the second embodiment, substantially the same effect as that of the first embodiment can be obtained, and the screw is not formed on the connecting pin 12, and the male screw member 41 which is a separate member from the connecting pin 12. And the female screw member 42, the possibility of unintentional loosening of the screw is further reduced even when an impact force such as a combustion load acts on the connecting pin 12, and reliability and durability are reduced. Is further improved.
[0036]
8 and 9 show a pin connection structure according to a third embodiment of the present invention. FIG. 8 is an assembled sectional view, and FIG. 9 is an exploded sectional view. The basic configuration is substantially the same as in the second embodiment, but the axial length of the second large-diameter member 31C, particularly the fitting protrusion 33C, is set longer than that of the first large-diameter member 31A. The internal thread 45 is formed on the inner periphery of the flange through-hole 39 of the second large-diameter member 31C, and the male thread member 41C has a longer axial dimension than the male thread member (41) of the second embodiment. Is different from the second embodiment in that the length is set slightly shorter than the connecting pin 12 and the female screw member (42) of the second embodiment is omitted.
[0037]
During assembly, the male screw member 41C is inserted into the pin through-hole 37 of the connecting pin 12 through the flange through-hole 39 of the first large-diameter member 31A and screwed into the female screw 45 of the second large-diameter member 31C. Thus, both large-diameter members 31 </ b> A and 31 </ b> C are fixed to both ends of the connecting pin 12.
[0038]
According to the third embodiment, in addition to obtaining the same effect as that of the second embodiment, the number of parts is reduced as the female screw member (42) is omitted, which is advantageous in terms of cost.
[0039]
FIG. 10 is an assembled cross-sectional view of the pin connection structure according to the fourth embodiment of the present invention, and FIG. 11 is an exploded cross-sectional view thereof. The basic configuration is substantially the same as in the third embodiment, but the first large diameter member 31D has the same shape as the second large diameter member 31C of the third embodiment, that is, the same parts, and the first large diameter. The shaft portion 46 of the male screw member 41D is reduced in diameter so as to be able to penetrate the member 31D, and the diameter of the shaft portion 46 is set smaller than the minimum inner diameter of the female screw 45. ing.
[0040]
In assembly, the male screw member 41D is first screwed into the female screw 45 of the first large-diameter member 31D, and the male screw member 41D is continuously rotated, so that the male screw 43 at the distal end of the male screw member 41D becomes the first large-diameter member. The large-diameter members 31D and 31C are fixed to both ends of the connecting pin 12 by passing through 31D and screwing the leading end thereof into the female screw 45 of the other second large-diameter member 31C through the pin through hole 37.
[0041]
According to the fourth embodiment, since the first large-diameter member 31D and the second large-diameter member 31C are common components, it is possible to reduce the component unit price. However, although the male screw member 41D must be rotated excessively so that the tip of the male screw member 41D passes through the first large-diameter member 31D, the male screw member is generally used with a power tool in the production line. Therefore, the influence on the assembly work is very small.
[0042]
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.
[0043]
The technical ideas of the present invention that can be grasped from the above embodiments are listed together with their effects.
[0044]
(1) A first link member having a first pin boss and a second pin boss disposed so as to face each other in a bifurcated manner, and a second link member having a third pin boss disposed between the first pin boss and the second pin boss. And a connecting pin for rotatably connecting the first link member and the second link member through the first to third pin bearing holes formed in the first to third pin bosses, respectively. A pin coupling structure of a link mechanism having a first large-diameter member having a larger diameter than the first pin bearing hole of the first pin boss and a larger diameter than the second pin bearing hole of the second pin boss. A second large-diameter member, and a fixing member that fixes the first large-diameter member to one end in the axial direction of the connecting pin, and fixes the second large-diameter member to the other axial end of the connecting pin, In addition, relative rotation around the axis is applied to each large-diameter member and connecting pin. As stop, providing a fitting portion fitted to each other.
[0045]
Since the first link member and the second link member and the connecting pin can rotate with each other and have a full floating structure excellent in lubricity and durability, a frictional force acts on a sliding contact portion between the large-diameter member and the pin boss. However, since the large-diameter member and the connecting pin are prevented from rotating and restrained in the rotational direction by the fitting portion, the rotational force due to the frictional force is directly applied to the fixing portion by the fixing member such as a fixing bolt. Never communicate to. Therefore, even if the above-mentioned contact frictional force continuously acts in the direction of loosening and rotation of the fixing bolt screw, even in the worst case, the bolt may fall off due to the loosening of the screw, the large-diameter member will drop off, Axial positioning failures and dropouts can be reliably prevented and avoided.
[0046]
When assembling, for example, a connecting pin is inserted into the pin bosses of the first and link members, and a large diameter member is fixed to both ends of the connecting pin with a fixing member such as a bolt to complete the assembling operation. Therefore, unlike the conventional pin connection structure using a snap ring, an operation such as shrinking while holding the snap ring as an elastic body becomes unnecessary, and the assembling operation is extremely easy.
[0047]
Unlike the connecting structure using a snap ring, there is no need for an extra pin boss or connecting pin area outside the large-diameter member in the axial direction, ensuring the contact area between the pin boss and the connecting pin, and reducing the size and weight of the pin boss. Can be achieved at a high level.
[0048]
(2) The fitting portion is provided on each large-diameter member, and is fitted into a fitting protrusion that protrudes in the axial direction along the axial center thereof, and is recessed in the axial end surface of the connecting pin. A fitting hole for fitting. In this case, by fitting the fitting protrusion into the fitting hole, rotation of the large-diameter member with respect to the connecting pin can be prevented and restrained. Can be done.
[0049]
(3) The outer periphery of the fitting protrusion and the inner periphery of the fitting hole are non-circular.
[0050]
(4) The outer periphery of the fitting protrusion and the inner periphery of the fitting hole are polygonal. The effect of stopping the large-diameter member can be obtained at the sides and corners of the polygon. In addition, when forming the fitting hole on the end face of the cylindrical connecting pin, if the fitting hole is a regular polygon, the radial dimension of the fitting hole can be kept relatively small, and in a limited space. This makes it possible to obtain a sufficient anti-rotation effect.
[0051]
(5) The fixing member penetrates the first large diameter member and is screwed to one end in the axial direction of the connecting pin; and the second fixing member penetrates the second large diameter member to the other end in the axial direction of the connecting pin. And a second fixing bolt to be screwed together. As the fixing bolt, an inexpensive screw plug or the like as a general / general machine element part can be used as it is, and the manufacturing cost can be reduced as compared with the case of producing a specially shaped screw.
[0052]
(6) The fixed member extends through the first large-diameter member and extends into a pin through hole formed through the axial center of the connecting pin, and a male screw member having a male screw formed on the outer periphery of the tip thereof; A female screw member that extends through the second large-diameter member into the pin through-hole and has a female screw that engages with the male screw of the male screw member on the inner periphery of the tip.
[0053]
In this case, the screw connection between the large-diameter member and the connecting pin can be established without forming a female screw on the connecting pin side. Since the screw fastening portion is located at a location substantially separated from or cut off from the connecting pin (in the through hole of the connecting pin), when an impact force such as a combustion load acts on the outer peripheral surface of the connecting pin In addition, there is no possibility that the meshing between the female screw and the male screw is deteriorated, the screw is difficult to loosen, and the reliability and durability can be further improved.
[0054]
(7) The fixing member includes a male screw member that passes through the first large-diameter member and the connecting pin and is screwed into the second large-diameter member. It is not necessary to screw the screw member from both ends of the connecting pin, and two large-diameter members can be fixed to both ends of the connecting pin by one male screw member, so that the number of parts can be reduced and the cost can be reduced.
[0055]
(8) The first large diameter member and the second large diameter member have the same shape. By sharing the parts in this way, the unit unit price can be reduced and the cost can be reduced.
[0056]
(9) 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 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 arrangement space for the pin bearing structure, particularly the dimensional restriction in the pin axial direction, is severe, so the pin connection structure of the present invention is extremely effective.
[0057]
(10) 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 arrangement space with respect to the pin bearing structure, in particular, the dimensional restriction in the pin axis direction is severe, so the pin coupling structure of the present invention is extremely effective.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of an essential part of an internal combustion engine showing a variable compression ratio mechanism as a multi-link type piston-crank mechanism using a pin coupling structure according to the present invention.
2 is a cross-sectional view taken along the line AA of FIG. 1 showing the pin connection structure of the first embodiment.
FIG. 3 is an exploded cross-sectional view showing the pin connection structure of the first embodiment.
FIG. 4 is a front view (a), a sectional view (b), and a rear view (c) showing a large-diameter member alone.
FIGS. 5A and 5B are a front view and a cross-sectional view showing a connecting pin as a single unit. FIGS.
6 is a cross-sectional view taken along the line AA of FIG. 1 showing a pin coupling structure of a second embodiment.
FIG. 7 is an exploded sectional view showing a pin connection structure of a second embodiment.
FIG. 8 is a cross-sectional view taken along line AA of FIG. 1 showing a pin coupling structure of a third embodiment.
FIG. 9 is an exploded cross-sectional view showing a pin coupling structure of a third embodiment.
10 is a cross-sectional view taken along the line AA of FIG. 1 showing a pin connection structure of a fourth embodiment.
FIG. 11 is an exploded sectional view showing a pin connection structure of a fourth embodiment.
[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. Second pin boss
24 ... 1st bearing hole
25 ... second bearing hole
26 ... Third pin boss
27 ... Third bearing hole
31A ... 1st large diameter member
31B ... Second large diameter member
33 ... Fitting protrusion (fitting part)
34 ... Fitting hole (fitting part)
36A ... First fixing bolt
36B ... Second fixing bolt

Claims (11)

A first link member having a first pin boss and a second pin boss arranged to face each other in a bifurcated manner;
A second link member having a third pin boss disposed between the first pin boss and the second pin boss;
A link having a connecting pin that rotatably passes through the first to third pin bearing holes respectively formed in the first to third pin bosses and rotatably connects the first link member and the second link member. A pin connection structure of the mechanism,
A first large diameter member having a larger diameter than the first pin bearing hole of the first pin boss;
A second large-diameter member having a larger diameter than the second pin bearing hole of the second pin boss;
A different member from the the large diameter member, is fixed to the first large-diameter member in the one axial end of the connecting pin, and the threaded member for fixing the second large-diameter member in the other axial end of the connecting pin Have
And the pin connection structure of the link mechanism which provided the fitting part which mutually fits so that each large diameter member and a connection pin may prevent relative rotation around an axis | shaft.   The fitting portion is provided in each large-diameter member, and is fitted in a fitting protrusion that protrudes in the axial direction along the axial center thereof, and an axial end surface of the connecting pin, and the fitting protrusion is fitted. The pin connection structure of the link mechanism according to claim 1, further comprising a fitting hole.   The pin connection structure of the link mechanism according to claim 2, wherein an outer periphery of the fitting protrusion and an inner periphery of the fitting hole are non-circular.   The pin connection structure for a link mechanism according to claim 2, wherein the outer periphery of the fitting protrusion and the inner periphery of the fitting hole are polygonal. The screw member passes through the first large-diameter member and is screwed into one end of the connecting pin in the axial direction, and the second fixing member is passed through the second large-diameter member and is screwed into the other end of the connecting pin in the axial direction. The pin connection structure of the link mechanism according to any one of claims 1 to 4, further comprising a second fixing bolt. The screw member penetrates the first large-diameter member, extends into a pin through hole formed so as to penetrate along the axial center of the connecting pin, and a male screw member having a male screw formed on the outer periphery of the tip thereof, The internal thread member which penetrated the diameter member, extended in the said pin through-hole, and the internal thread member in which the external thread of the said external thread member was screwed together was formed in the front-end | tip inner periphery. Pin linkage structure of the link mechanism. The screw member, a pin connection structure of the link mechanism according to claim 1 having a male screw member to be screwed into the second large-diameter member through the connecting pin and the first large-diameter member.   The pin connection structure for a link mechanism according to claim 7, wherein the first large-diameter member and the second large-diameter member have the same shape. A lower link rotatably attached to a crank pin 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. 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 8, wherein the upper pin is the connection pin. A lower link rotatably attached to a crank pin 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; A control link that links the link and the engine 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 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 8, wherein at least one of the upper pin and the control pin is the connection pin. The pin connection structure for a link mechanism according to any one of claims 1 to 10, wherein an axial dimension of the connecting pin is substantially equal to an axial dimension of the first and second pin boss portions of the first link member.

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