JP5625986B2 - Multi-link piston-crank mechanism for internal combustion engine, control shaft for multi-link piston-crank mechanism, or method for manufacturing control shaft for multi-link piston-crank mechanism - Google Patents

Description

  The present invention relates to a multi-link piston-crank mechanism for an internal combustion engine, a control shaft for a multi-link piston-crank mechanism, and a method for manufacturing a control shaft for a multi-link piston-crank mechanism.

  For example, Patent Document 1 discloses a first link that is pivotably coupled to a piston, and a second link that is pivotally coupled to the first link and is rotatably mounted on a crankpin of a crankshaft. A link, a control shaft having an eccentric shaft portion, and a third link that is rotatably connected to the second link via a connecting pin and is swingably connected to the eccentric shaft portion of the control shaft. In the variable compression ratio mechanism of the internal combustion engine that variably controls the compression ratio of the internal combustion engine by rotating the control shaft according to the engine operating state and changing the position of the eccentric shaft portion, the compression ratio is independently set for each cylinder. There is disclosed one in which adjustable adjusting means is provided at the lower part of the third link.

  In Patent Document 1, a bolt hole having a thread groove is provided in the lower portion of the third link, and an adjustment bolt is screwed into the bolt hole, and a pair of halves are formed in the lower portion of the third link. An eccentric sleeve bearing of structure is provided. And the outer periphery of this eccentric sleeve bearing and the front-end | tip of an adjustment bolt are engaging, and since an eccentric sleeve bearing rotates by rotating an adjustment bolt and advancing and retreating, a 3rd link and a 2nd link are connected. Fine adjustment of the distance between the connecting pin and the swing center of the lower part of the third link is possible, and the compression ratio can be finely adjusted.

JP 2005-69027 A

  However, in the variable compression ratio mechanism disclosed in Patent Document 1, since the eccentric sleeve bearing (bearing metal) has a pair of half-split structures, the dividing line by the split surface of the eccentric sleeve bearing adjusts the compression ratio. When the load based on the combustion load, which is a relatively large load, is transmitted between the third link and the load vector line (the center of the connection pin connecting the third link and the second link and the third There is a possibility that the above dividing line may exist on the sliding surface between the eccentric sleeve bearing and the eccentric shaft portion in the vicinity of the straight line connecting the swing center of the lower part of the link), and there is a possibility that the lubrication performance may be disadvantageous. .

  Accordingly, the present invention provides a plurality of link members that connect a piston and a crankshaft, a control link that restricts the movement of the plurality of link members, and an eccentric shaft portion that is pivotally connected to one end of the control link. A multi-link type piston of an internal combustion engine in which the top dead center position of the piston changes and the compression ratio changes by changing the position of the eccentric shaft portion by rotation of the control shaft -Assumes a crank mechanism. A cylindrical eccentric sleeve press-fitted into the eccentric shaft portion is provided, and the top dead center position of the piston can be adjusted for each cylinder by rotating the eccentric sleeve relative to the eccentric shaft portion. ing. The eccentric sleeve is a separate part from the eccentric shaft part of the control shaft, and the top dead center position of each piston can be finely adjusted for each cylinder by rotating the eccentric sleeve relative to the eccentric shaft part. Become.

  According to the present invention, since the compression ratio is adjusted by the rotation of the cylindrical eccentric sleeve, even if the bearing metal on the outer peripheral side of the eccentric sleeve has a half structure, the dividing line generated on the split surface is There is no rotational movement by adjusting the compression ratio. Therefore, when a combustion load as a relatively large load is applied from the third link side, the control link near the load vector line (a straight line connecting the swing center at one end of the control link and the swing center at the other end of the control link). The possibility that a parting line exists on the sliding surface of the connecting portion between the control shaft and the control shaft is eliminated, and the lubrication performance is improved as compared with the case where the eccentric sleeve is constituted by two halved members. In other words, it is possible to finely adjust the compression ratio between the respective cylinders without deteriorating the lubrication performance of the sliding surface between the eccentric sleeve and the control link and without disassembling the multi-link piston-crank mechanism. It becomes possible.

BRIEF DESCRIPTION OF THE DRAWINGS Explanatory drawing which shows schematic structure of the multilink type piston-crank mechanism of the internal combustion engine to which this invention was applied. The side view which shows the structure of the control shaft vicinity. The front view of a control axis. The side view of a control axis. Explanatory drawing which expanded and showed the principal part in the multiple link type piston-crank mechanism of the internal combustion engine to which this invention was applied. It is explanatory drawing which shows the eccentric sleeve used for the double link type piston-crank mechanism of the internal combustion engine to which this invention was applied, (a) is a left view, (b) is a front view, (c) is a right view. . Explanatory drawing which showed typically the correlation of the static friction coefficient between an eccentric sleeve and an eccentric shaft part, and a lubrication state. Explanatory drawing which expanded and showed the principal part in 2nd Embodiment of this invention. It is explanatory drawing which shows a taper screw, (a) is a left view, (b) is a front view. Explanatory drawing which showed typically the adjustment method of the compression ratio in 2nd Embodiment of this invention. Explanatory drawing which showed typically the control axis in 3rd Embodiment of this invention. It is explanatory drawing which shows the main shaft member which comprises the control shaft in 3rd Embodiment of this invention, (a) is a left view, (b) is a front view. It is explanatory drawing which shows the eccentric shaft member which comprises the control shaft in 3rd Embodiment of this invention, (a) is a left view, (b) is a front view. It is explanatory drawing which shows the connection member which comprises the control shaft in 3rd Embodiment of this invention, (a) is a left view, (b) is a front view. It is explanatory drawing which shows the positioning member which comprises the control shaft in 3rd Embodiment of this invention, (a) is a front view, (b) is a right view. It is explanatory drawing which shows the basic shaft member which comprises the control shaft in 3rd Embodiment of this invention, (a) is a left view, (b) is a front view. It is explanatory drawing which showed typically the assembly procedure of the control shaft in 3rd Embodiment of this invention, Comprising: (a) is a 1st process, (b) is a 2nd process, (c) is a 3rd Step (d) shows the fourth step, and (e) shows the control shaft that has been assembled. Explanatory drawing which showed typically the control axis of the comparative example comprised from the single member. Explanatory drawing which showed typically the control axis of the comparative example comprised from the single member. Explanatory drawing which showed typically the problem in the control shaft of a comparative example. Explanatory drawing which showed typically the problem in the control shaft of a comparative example.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. 1 and 2 show an example of a basic configuration of a multi-link type piston-crank mechanism to which the present invention is applied, and shows a case where it is applied to an in-line four-cylinder internal combustion engine. . FIG. 1 is an explanatory diagram showing a schematic configuration of a multi-link piston-crank mechanism of an internal combustion engine, and FIG. 2 is a side view showing a configuration in the vicinity of a control shaft 6 (described later).

  The multi-link type piston-crank mechanism includes an upper link 3 and a lower link 4 that connect the piston 1 and the crankshaft 2, a control link 5 that restricts the movement of the upper link 3 and the lower link 4, and one end of the control link 5. And a control shaft 6 having an eccentric shaft portion 7 connected so as to be swingable.

  The piston 1 is slidably disposed in a cylinder 10 formed in the cylinder block 9 and is connected to one end (upper end in FIG. 1) of the upper link 3 via a piston pin 11 so as to be swingable. .

  The other end (the lower end in FIG. 1) of the upper link 3 is rotatably connected to one end of the lower link 4 via the first connecting pin 12.

  The lower link 4 is rotatably attached to the crankpin 13 of the crankshaft 2 at the center thereof.

  The crankshaft 2 includes a plurality of journal portions 14 and a crank pin 13, and the journal portion 14 is rotatably supported by the cylinder block 9 by a crank bearing bracket 15 of the cylinder block 9. The crank pin 13 is eccentric from the journal portion 14 by a predetermined amount, and the lower link 4 is rotatably connected thereto.

  One end (upper end in FIG. 1) of the control link 5 that restricts the movement of the lower link 4 is rotatably connected to the other end of the lower link 4 via the second connecting pin 16, and the other end (in FIG. 1). The lower end is supported by a cylinder block 9 which is a part of the internal combustion engine body so as to be swingable. The other end of the control link 5 can be displaced with respect to the main body of the internal combustion engine in order to change the compression ratio of the internal combustion engine. Specifically, a control shaft 6 extending in parallel with the crankshaft 2 is provided, and the other end of the control link 5 is rotatably fitted to an eccentric shaft portion 7 provided eccentric to the control shaft 6.

As shown in FIGS. 1 to 4, the control shaft 6 includes a main shaft portion 8 that is rotatably supported between the crank bearing bracket 15 and the control shaft bearing bracket 18, and a predetermined amount e with respect to the main shaft portion 8. _And an eccentric shaft portion 7 which is eccentric by ₀ . The eccentric shaft portion 7 is set to have a larger diameter than the main shaft portion 8, and the connecting portion 26 between the eccentric shaft portion 7 and the main shaft portion 8 has a smaller diameter than either the eccentric shaft portion 7 or the main shaft portion 8. It has become. An actuator 19 such as an electric motor is attached to one end of the control shaft 6. In the present embodiment, the control shaft 6 has eccentric shaft portions 7 formed at four locations, and the control links 5 of four cylinders are connected to the eccentric shaft portions 7 respectively.

  Therefore, when the control shaft 6 is rotationally driven by the actuator 19 to change the compression ratio, the center position of the eccentric shaft portion 7 that becomes the swing fulcrum 17 of the control link 5 moves relative to the engine body. As a result, the motion constraint condition of the lower link 4 by the control link 5 changes, the stroke position of the piston 1 with respect to the crank angle changes, and the compression ratio is changed accordingly.

  The present invention is not limited to a specific type of multi-link variable compression ratio device as shown in the figure, but can be applied to various types of variable compression ratio devices using a multi-link type piston-crank mechanism. It is possible.

  Here, as shown in FIGS. 5 and 6, an eccentric sleeve 20 having a substantially cylindrical shape is press-fitted into the periphery (outer periphery) of the eccentric shaft portion 7 of the control shaft 6 which is a main part of the present invention. Yes. The eccentric sleeve 20 is fixed by press-fitting based on a sufficient press-fitting allowance without rotating relative to the eccentric shaft portion 7 during engine operation. Therefore, according to the present invention, instead of adjusting the center position of the connecting pin hole (the inner periphery of the bearing metal) of the control link as in the prior art, the eccentric shaft portion 7 (the outer periphery on the shaft side) of the control shaft 6 is adjusted. The center position is adjusted.

  The eccentric sleeve 20 includes a cylindrical portion 21 that is press-fitted into the eccentric shaft portion 7, and a rotation angle adjustment portion 22 that is formed at one end of the cylindrical portion 21. The cylindrical portion 21 has an outer peripheral surface that is rotatably fitted to a slide bearing (metal) 24 attached to the other end side of the control link 5 with respect to an inner peripheral surface 23 that faces the outer peripheral surface of the eccentric shaft portion 7. 25 is formed to be eccentric by a predetermined amount e. The rotation angle adjusting part 22 is a convex part formed in a bowl shape on the entire circumference of one end of the cylindrical part 21, and is formed so that the outer shape is a hexagon when the eccentric sleeve 20 is viewed from the axial direction. Yes.

  Here, since the eccentric sleeve 20 is press-fitted into the eccentric shaft portion 7 of the control shaft 6, the inner peripheral surface 23 of the cylindrical portion 21 of the eccentric sleeve 20 and the outer peripheral surface of the eccentric shaft portion 7 are in direct contact. There will always be a part. In other words, the gap between the inner peripheral surface 23 of the cylindrical portion 21 of the eccentric sleeve 20 and the outer peripheral surface of the eccentric shaft portion 7 is set so as not to be at least in a fluid lubrication state.

  As shown in FIG. 3, the control shaft 6 in the present embodiment has four eccentric shaft portions 7, and the eccentric shaft portions 7a and 7b are arranged from the right side in FIG. 3 with the eccentric shaft portions 7c and 7d. In FIG. 3, an eccentric sleeve 20 is assembled from the left side in FIG. This is because the outer diameters of the eccentric shaft portions 7a and 7d are set smaller than the outer diameter of the eccentric shaft portions 7b and 7c (for example, about 1 mm). However, the inner diameter of the cylindrical portion 21 of the eccentric sleeve 20 that is press-fitted into the eccentric shaft portions 7a and 7d is set smaller than the inner diameter of the cylindrical portion 21 of the eccentric sleeve 20 that is press-fitted into the eccentric shaft portions 7b and 7c. The press-fitting allowance δ (the difference between the outer diameter of the eccentric shaft portion 7 and the inner diameter of the cylindrical portion 21 of the eccentric sleeve 20) is set to be the same for all cylinders. Further, the outer diameter of the eccentric sleeve is configured to be the same for all the cylinders, and the common control link 5 can be used for all the cylinders.

The eccentric amount e corresponding to the deviation between the center of the outer diameter and the center of the inner diameter of the eccentric sleeve 20 is the same for all the cylinders, and is set to the minimum amount of eccentricity necessary for adjusting the variation in the compression ratio between the cylinders. The eccentric amount e ₀ of the eccentric shaft portion 7 of the control shaft 6 with respect to the main shaft portion 8 is set to be smaller.

  Further, the press-fit allowance δ with respect to the eccentric shaft portion 7 of the eccentric sleeve 20 is an expected value μe of a static friction coefficient generated between the inner peripheral surface 23 of the cylindrical portion 21 of the eccentric sleeve 20 and the outer peripheral surface of the eccentric shaft portion 7. Is set to be smaller than the actual coefficient of static friction μa.

Here, the expected value μe of the static friction coefficient is calculated using the following equation (1).
[Equation 1]

T in the formula (1) is a torque applied to the eccentric sleeve 20, and a load F applied to the eccentric sleeve 20 from the control link 5 side (for example, assuming the largest load when a combustion load is applied) and the eccentricity. When expressed using the amount of eccentricity e of the sleeve 20, T = F × e. A in the formula (1) is an inner peripheral area of the eccentric sleeve 20 and is expressed by using the radius b of the inner diameter of the cylindrical portion 21 of the eccentric sleeve 20 and the length l of the cylindrical portion 21 of the eccentric sleeve 20. A = 2πbl. In equation (1), a is the radius of the outer diameter of the cylindrical portion 21 of the eccentric sleeve 20, υ _B is the Poisson ratio of the control shaft 6, υ _H is the Poisson ratio of the eccentric sleeve 20, and E _B is the control shaft. The longitudinal elastic modulus E _H is the longitudinal elastic modulus of the eccentric sleeve 20.

  In setting the expected value μe of the static friction coefficient to be smaller than the actual static friction coefficient μa from this equation (1), if it is not desired to increase the press-fitting allowance δ, for example, the inner peripheral area of the eccentric sleeve 20 It can be seen that the press-fitting allowance δ may be set to be relatively small by increasing A. That is, the dimension of each part of the eccentric sleeve 20 can be appropriately set so that the expected value μe of the static friction coefficient is smaller than the actual static friction coefficient μa using the formula (1).

  The actual static friction coefficient μa is set to 0.01 or more so that the mixed lubrication state or the boundary lubrication state is obtained so as not to be in the fluid lubrication state. As shown in FIG. 7, when a fluid lubrication state exists between the inner peripheral surface 23 of the cylindrical portion 21 of the eccentric sleeve 20 and the outer peripheral surface of the eccentric shaft portion 7, the cylindrical portion 21 of the eccentric sleeve 20 This is a case where the static friction coefficient μ (μa) generated between the inner peripheral surface 23 and the outer peripheral surface of the eccentric shaft portion 7 is 0.01 or less. That is, the state in which the eccentric sleeve 20 is press-fitted into the eccentric shaft portion 7 of the control shaft 6 is a stationary state that occurs between the inner peripheral surface 23 of the cylindrical portion 21 of the eccentric sleeve 20 and the outer peripheral surface of the eccentric shaft portion 7. This is a state where the friction coefficient μ (μa) is set to be larger than 0.01, and is either a mixed lubrication state or a boundary lubrication state.

  In this multi-link type piston-crank mechanism, for example, when adjusting the compression ratio during the assembly process of the internal combustion engine, all link parts (upper link 3, lower link 4, control link 5) are assembled. Thereafter, the control shaft 6 is fixed so as not to rotate, the height of the piston 1 of each cylinder is measured, and each cylinder is determined by comparing the measured height with a predetermined piston height corresponding to the angle of the control shaft 6 at that time. The required rotation angle of the eccentric sleeve 20 is calculated, the jig is engaged with the rotation angle adjusting unit 22 of the eccentric sleeve 20, the eccentric sleeve 20 of each cylinder is rotated, and the height of the piston 1 is adjusted.

  In the first embodiment of the present invention, the eccentric sleeve 20 does not rotate relative to the eccentric shaft portion 7 during engine operation, while the compression ratio is adjusted by adjusting the eccentric sleeve 20 to the eccentric shaft portion 7. By rotating relative to each other, the top dead center position of the piston 1 can be finely adjusted for each cylinder, and the compression ratio between the cylinders can be finely adjusted without disassembling the multi-link piston-crank mechanism. It becomes possible to carry out easily.

  In particular, the boundary sleeve 20 and the eccentric shaft portion 7 may be in a boundary lubrication state or in some cases a mixed lubrication state as described above. It is possible to suppress the rotation of the eccentric sleeve 20. Thus, the bearing metal is divided on the sliding surface between the metal bearing and the eccentric shaft portion in the vicinity of the load vector line while enabling the fine adjustment of the compression ratio by an extremely simple configuration of press-fitting the cylindrical eccentric sleeve 20. Lubrication performance can be improved by eliminating the possibility of the presence of lines. Since the press-fitting allowance does not need to be extremely increased, the rotational torque applied to the eccentric sleeve 20 when finely adjusting the compression ratio is small, and the compression ratio can be easily adjusted.

  Based on such advantages, the eccentric sleeve 20 is rotated relative to the eccentric shaft portion 7 by engaging a jig with the rotation angle adjusting portion 22 formed at one end of the cylindrical portion 21 of the eccentric sleeve 20. Therefore, the eccentric sleeve 20 press-fitted into the eccentric shaft portion 7 can be inserted into the eccentric shaft portion 7 without increasing the number of parts in the connecting portion between the control link 5 and the eccentric shaft portion 7 of the control shaft 6. Can be rotated. For this reason, the configuration of the connecting portion between the control link 5 and the eccentric shaft portion 7 of the control shaft 6 is increased, and the number of parts of the connecting portion between the control link 5 and the eccentric shaft portion 7 of the control shaft 6 is increased. It is possible to suppress an increase in weight and cost.

  Since the cylindrical eccentric sleeve 20 is press-fitted into the eccentric shaft portion 7 so that no play occurs between the eccentric sleeve 20 and the eccentric shaft portion 7, the eccentric sleeve 20 and the eccentric sleeve 20 are eccentric during operation of the internal combustion engine. It is possible to prevent abnormal noise from occurring with the shaft portion 7. Moreover, there is no need to manufacture the bearing metal in an eccentric manner, and it is not difficult to manufacture the bearing metal or to ensure the performance of the bearing metal.

  Further, the eccentric sleeve 20 is press-fitted into the eccentric shaft portion 7, and the static friction coefficient μ generated between the inner peripheral surface 23 of the cylindrical portion 21 of the eccentric sleeve 20 and the outer peripheral surface of the eccentric shaft portion 7 is 0.01. Therefore, the lubrication between the outer peripheral surface of the eccentric shaft portion 7 and the inner peripheral surface 23 of the cylindrical portion 21 of the eccentric sleeve 20 is not at least fluid lubrication, and boundary lubrication or The outer peripheral surface of the eccentric shaft portion 7 and the inner peripheral surface 23 of the cylindrical portion 21 of the eccentric sleeve 20 are in contact with each other over the entire circumference. In other words, the inner peripheral surface 23 of the cylindrical portion 21 of the eccentric sleeve 20 is at least partially in contact with the outer peripheral surface of the eccentric shaft portion 7 (solid surfaces are in contact with each other). This is advantageous in fixing the eccentric sleeve 20.

  In particular, the inner peripheral surface 23 of the cylindrical portion 21 of the eccentric sleeve 20 and the outer peripheral surface of the eccentric shaft portion 7 are prevented so that the eccentric sleeve 20 does not move relative to the eccentric shaft portion 7 due to the combustion pressure acting on the piston 1. If the static friction coefficient μ generated during the period is set, it is possible to suppress the change in the compression ratio with time and to suppress the variation in the compression ratio between the cylinders. Further, even if the eccentric sleeve 20 is press-fitted into the eccentric shaft portion 7 so that the movement in the circumferential direction of the eccentric shaft portion 7 is restricted, the change in the compression ratio with time can be suppressed, and the compression ratio between the cylinders can be reduced. The occurrence of variation can be suppressed.

The eccentric amount e of the eccentric sleeve 20 is set to such an extent that the variation in the compression ratio between the cylinders can be adjusted, and is smaller than the eccentric amount e ₀ of the eccentric shaft portion 7, and the compression ratio between the cylinders. Since the minimum amount of eccentricity necessary for variation adjustment is set, the influence of the combustion pressure and inertial force applied to the eccentric sleeve 20 is reduced, and as a result, the eccentric sleeve 20 press-fitted into the eccentric shaft portion 7 is replaced with the eccentric shaft portion 7. There is an effect of reducing torque to be rotated.

  Note that the rotation angle adjusting unit 22 in the first embodiment has a shape that can be engaged with a predetermined jig in a state where the other end side of the control link 5 is assembled to the eccentric shaft portion 7 into which the eccentric sleeve 20 is press-fitted. If so, the outer shape is not limited to a hexagon.

  Hereinafter, although other embodiments of the present invention will be described, the same components as those in the first embodiment described above are denoted by the same reference numerals, and redundant description will be omitted.

  A second embodiment of the present invention will be described with reference to FIGS. The second embodiment has substantially the same configuration as the multi-link piston-crank mechanism of the first embodiment, but in the second embodiment, the control link 5 and the eccentric shaft portion 31 of the control shaft 6 The connecting portion is configured differently, and has a fixing means 33 for fixing the eccentric sleeve 32 to the eccentric shaft portion 31 by a force acting in the thrust direction of the eccentric shaft portion 31.

  Specifically, in the second embodiment, as shown in FIG. 8, a protrusion 34 protruding in a hook shape is formed at one end of the eccentric shaft portion 31.

  Further, the eccentric sleeve 32 has a constant cylindrical shape over its entire length, but its inner peripheral surface is formed in a stepped shape so that the inner diameter on one end side is relatively small. Is formed. That is, the eccentric sleeve 32 has a small diameter portion 35 having a relatively small inner diameter and a large diameter portion 36 having a relatively large inner diameter, and the small diameter portion 35 is press-fitted into the eccentric shaft portion 31 of the control shaft 6. . Further, the eccentric sleeve 32 has a female screw 37 as a rotation angle adjusting portion on the outer peripheral surface outside the portion connected to the other end of the control link 5, and a direction perpendicular to the axis of the eccentric sleeve 32 (perpendicular to the paper surface in FIG. 8). Direction). The female screw 37 is provided for the operator to screw the rotation angle adjusting bolt 38 when adjusting the compression ratio. The small diameter portion 35 and the large diameter portion 36 are formed concentrically, and both are eccentric by a predetermined amount with respect to the axis of the eccentric sleeve 32.

  The fixing means 33 is screwed onto the outer periphery of the taper screw 39, a cylindrical taper screw 39 inserted into the eccentric shaft portion 31 of the control shaft 6, a taper screw fixing nut 40 for fixing the taper screw 39 to the eccentric shaft portion 31, and the taper screw 39. And an eccentric sleeve fixing nut 41 that is pressed against the end face on the other end side of the eccentric sleeve 32 by tightening.

  As shown in FIGS. 8 and 9, the taper screw 39 includes a cylindrical straight portion 42 inserted into the space between the inner peripheral surface of the large-diameter portion 36 of the eccentric sleeve 32 and the outer peripheral surface of the eccentric shaft portion 31. , And slits 43 extending in the axial direction have taper portions 44 formed at three locations. On the outer periphery of the straight portion 42, a male screw 45 that is screwed with the eccentric sleeve fixing nut 41 is formed. On the outer periphery of the taper portion 44, a male screw 46 that is screwed into the taper screw fixing nut 40 is formed.

  In the second embodiment, after the eccentric sleeve 32 is press-fitted into the eccentric shaft portion 31, the taper screw 39 is inserted into the eccentric shaft portion 31, and the taper screw fixing nut 40 is tightened to thereby form the slit portion 43. 44 is compressed to fix the taper screw 39 to the eccentric shaft portion 31. In this state, the eccentric sleeve fixing nut 41 is tightened, and the eccentric sleeve 32 is sandwiched between the eccentric sleeve fixing nut 41 and the protrusion 34 of the eccentric shaft portion 31, thereby acting in the thrust direction of the eccentric shaft portion 31. The eccentric sleeve 32 is fixed to the eccentric shaft portion 31 using force.

  Further, as shown in FIG. 10, when the eccentric sleeve 32 is rotated with respect to the eccentric shaft portion 31 and the compression ratio is adjusted, the control shaft 6 is fixed, the eccentric sleeve fixing nut 41 is loosened, and the eccentric sleeve 32 is eccentric. The operator screws the rotation angle adjusting bolt 38 into the female screw 37 on the outer peripheral surface of the sleeve 32, and the operator rotates the rotation angle adjusting bolt 38 to rotate the eccentric sleeve 32 by a desired angle, thereby adjusting the compression ratio. To do.

  In the second embodiment as described above, substantially the same operational effects as those of the first embodiment described above can be obtained.

  In the second embodiment, since the eccentric sleeve 32 is fixed to the eccentric shaft portion 31 by the force acting in the thrust direction of the eccentric shaft portion 31, the eccentric sleep 32 and the eccentric shaft portion 31 are also fixed. It becomes possible to securely fix the gap. Therefore, in the second embodiment, the space between the inner peripheral surface 23 of the eccentric sleeve 32 (the inner peripheral surface of the small diameter portion 35) and the outer peripheral surface of the eccentric shaft portion 31 is not limited to being fixed only by press-fitting.

  A third embodiment of the present invention will be described. The third embodiment has substantially the same configuration as the multi-link type piston-crank mechanism of the first embodiment described above, but the control shaft 51 in the third embodiment is a single unit by forging, casting, or the like. It is not comprised from these members, but is comprised by the several member.

As shown in FIG. 11, the control shaft 51 in the third embodiment includes a main shaft portion 52 that is rotatably supported between the crank bearing bracket 15 and the control shaft bearing bracket 18, and the main shaft portion 52. An eccentric shaft portion 53 that is eccentric by a predetermined amount e _0, a connecting portion 54 that is connected to an actuator (not shown) that drives the control shaft 51, and a positioning portion that positions the control shaft 51 in the thrust direction (axial direction) 55.

  In the third embodiment, the control shaft 51 is formed with four eccentric shaft portions 53 and five main shaft portions 52, and the main shaft portions 52 and the eccentric shaft portions 53 are alternately provided along the axial direction thereof. It becomes the composition. That is, the eccentric shaft portion 53 is located between the pair of main shaft portions 52 when viewed along the axial direction of the control shaft 51. Each eccentric shaft portion 53 is connected to a control link 5 of four cylinders.

  The connecting portion 54 and the positioning portion 55 are located at approximately the center position in the axial direction of the control shaft 51, that is, approximately at the center in the cylinder row direction of the internal combustion engine. The positioning unit 55 also has a function as a mechanical stopper that defines the rotation amount of the control shaft 51, that is, the upper and lower limit positions of the rotation angle range of the control shaft 51.

  In the third embodiment, the control shaft 51 includes a main shaft member 61 serving as the main shaft portion 52, an eccentric shaft member 62 serving as the eccentric shaft portion 53, a connecting member 63 serving as the connecting portion 54, and a positioning portion. The positioning member 64 that is 55 and a long and narrow basic shaft member 67 that penetrates and connects these separate members 61, 62, 63, 64 are roughly constituted.

  As shown in FIG. 12, the main shaft member 61 has a circular tube shape and is rotatably supported between the crank bearing bracket 15 and the control shaft bearing bracket 18 with respect to the main shaft hole 61 a through which the basic shaft member 67 passes. An outer peripheral surface 61b, which is a cylindrical surface, is formed so as to be eccentric.

  As shown in FIG. 13, the eccentric shaft member 62 has a circular tubular shape, and an outer peripheral surface 62b, which is a cylindrical surface into which the eccentric sleeve 20 is press-fitted, is concentric with an eccentric shaft hole 62a through which the basic shaft member 67 passes. It is formed to become.

  As shown in FIG. 14, the connecting member 63 has a plate shape, and an engaging hole that engages with a connecting member hole 63 a through which the basic shaft member 67 passes and an actuator side (not shown) that is a drive source of the control shaft 51. 63b.

  As shown in FIG. 15, the positioning member 64 includes a disk-shaped base portion 65, a substantially fan-shaped sector portion 66 formed so that the arcuate tip side protrudes outside the base portion 65, and a basic shaft member 67. Is formed so as to have a positioning member hole 64a. The positioning member hole 64 a passes through the base portion 65 and the sector portion 66. The positioning member 64 positions the control shaft 51 in the thrust direction (axial direction) by the base portion 65 being abutted against the crank bearing bracket 15, and the side surface 66 a of the fan-shaped portion 66 as the control shaft 51 rotates. , 66b is applied to a stopper (not shown) to define the upper and lower limit positions of the rotation angle range of the control shaft 51.

  The inner diameters of the main shaft hole 61a of the main shaft member 61, the eccentric shaft hole 62a of the eccentric shaft member 62, the connecting member hole 63a of the connecting member 63, and the positioning member hole 64a of the positioning member 64 are formed to be the same in this embodiment. ing.

  As shown in FIG. 16, the basic shaft member 67 is a long and thin tubular member, and includes a main shaft hole 61a of the main shaft member 61, an eccentric shaft hole 62a of the eccentric shaft member 62, a connecting member hole 63a of the connecting member 63, and a positioning member. The outer diameter of the 64 positioning member holes 64a is set so that it can be inserted or press-fitted. In this embodiment, the outer diameter of the basic shaft member 67 is set to be the same as the hole diameter of each of the holes 61a, 62a, 63a, 64a, but the hole of each of the holes 61a, 62a, 63a, 64a. It is also possible to set it smaller than the diameter.

  The control shaft 51 is assembled in the procedure as shown in FIG. 17 using these members 61, 62, 63, 64, and 67.

  First, in the first step, as shown in FIG. 17A, before the eccentric shaft member 62 is assembled to the basic shaft member 67, the eccentric sleeve 20 is press-fitted in advance.

  Next, in the second step, as shown in FIG. 17B, the main shaft member 61, the eccentric shaft member 62 in which the eccentric sleeve 20 is press-fitted into the basic shaft member 67, the connecting member 63, and the positioning member 64 (illustrated). (Omitted) are inserted in order. In other words, the basic shaft member 67 is inserted into the holes 61a, 62a, 63a, 64a of these members 61, 62, 63, 64.

  In the third step, the members 61, 62, 63, 64 are arranged at predetermined positions on the basic shaft member 67 at a predetermined angle, and as shown in FIG. To expand. The tube expansion processing performed on the basic shaft member 67 is, for example, filling the inside of the basic shaft member 67 with a gas or a liquid and setting the gas or liquid inside the basic shaft member 67 to a high pressure, so that the outer diameter of the basic shaft member 67 is increased. Is extended over the entire length. By expanding the basic shaft member 67, the members 61, 62, 63 and 64 are fixed to the basic shaft member 67. The basic shaft member 67 may not be expanded to the full length, but only the portion where the members 61, 62, 63, 64 are arranged may be expanded.

  Next, in the fourth step, as shown in FIG. 17D, plugs 68 are driven into the front and rear ends of the expanded basic shaft member 67 to close the front and rear ends of the basic shaft member 67.

  As a result, as shown in FIG. 17E, the control shaft 51 in which the eccentric sleeve 20 is already press-fitted into the eccentric shaft portion 53 is obtained.

  Here, the control shaft 71 of the comparative example shown in FIG. 18 includes a main shaft portion 52, an eccentric shaft portion 53, a connecting portion 54, and a positioning portion 55 having the same shape as the control shaft 51 of the third embodiment described above. Although it has the same outer shape as the control shaft 51 of the third embodiment, it is configured by a single member by forging or casting. Since the shape of each part is the same shape as the control shaft 51 of the third embodiment described above, the same reference numerals are given, and the duplicate description is omitted.

  In such a control shaft 71, when the eccentric sleeve 20 is assembled to the eccentric shaft portion 53 of the control shaft 71, the two eccentric shaft portions 53a and 53b on the left side in FIG. 18 are viewed from the left side in FIG. The eccentric sleeve 20 is press-fitted from the right side in FIG. 18 with respect to the two right eccentric shaft portions 53c and 53d. That is, the eccentric sleeve 20 is moved in the axial direction of the control shaft 71 from the end of the control shaft 71 to the predetermined eccentric shaft portion 53.

  For example, as shown in FIG. 19, the eccentric sleeve 20 press-fitted into the eccentric shaft portion 53 b extends from one end portion (left end portion in FIG. 19) of the control shaft 71 along the axial direction of the control shaft 71. It moves to the eccentric shaft portion 53b while moving in a crank shape, and is press-fitted into the eccentric shaft portion 53b through the eccentric shaft portion 53a and the two main shaft portions 52, 52 located on both sides of the eccentric shaft portion 53a. It will be.

  Therefore, in order to allow the eccentric sleeve 20 to move in the axial direction of the control shaft 71 from the end of the control shaft 71 to the predetermined eccentric shaft portion 53, the degree of freedom in design of the control shaft 71 is limited. It will end up.

  Specifically, as shown in FIG. 20, if the outer diameter R1 of the eccentric shaft portion 53 is smaller than the outer diameter R2 of the main shaft portion 52, the eccentric sleeve 20 cannot pass through the main shaft portion 52. Cannot be moved in the axial direction of the control shaft 71 and the eccentric sleeve 20 cannot be press-fitted into the predetermined eccentric shaft portion 53. Therefore, in the control shaft 71 of the comparative example, it is necessary to make the outer diameter R1 of the eccentric shaft portion 53 larger than the outer diameter R2 of the main shaft portion 52.

  Further, in the control shaft 71 of the comparative example, even if the outer diameter of the eccentric shaft portion 53 is larger than the outer diameter of the main shaft portion 52, the outer diameter of the eccentric shaft portion 53 a located on the end side of the control shaft 71. If the outer diameter of the eccentric shaft portion 53b is smaller than that, the eccentric sleeve 20 cannot be press-fitted into the eccentric shaft portion 53b. This is because the eccentric sleeve 20 attached to the eccentric shaft portion 53b needs to pass through the eccentric shaft portion 53a, so that the inner diameter of the eccentric sleeve 20 needs to be larger than the outer diameter of the eccentric shaft portion 53a. Therefore, it is necessary to make the outer diameter of the eccentric shaft portion 53b located inside the eccentric shaft portion 53a located on the end side of the control shaft 71 larger.

  Furthermore, in the control shaft 71 of the comparative example, as shown in FIG. 21, the distance L1 between the main shaft portion 52 and the eccentric shaft portion 53 adjacent thereto is larger than the length L2 along the axial direction of the eccentric sleeve 20. When the length becomes shorter, the tip of the eccentric sleeve 20 abuts against the eccentric shaft portion 53 in a state where the eccentric sleeve 20 does not pass through the main shaft portion 52, and the eccentric sleeve 20 is moved to the position of the desired eccentric shaft portion 53. 71 cannot be moved. Therefore, in the control shaft 71 of the comparative example, the interval L1 between the main shaft portion 52 and the eccentric shaft portion 53 adjacent thereto needs to be longer than the length L2 of the eccentric sleeve 20.

  However, in the third embodiment, the control shaft 51 is composed of a main shaft member 61, an eccentric shaft member 62, a connecting member 63, a positioning member 64, and a basic shaft member 67. The main shaft member 61 and the eccentric sleeve 20 are press-fitted in advance. The basic shaft member 67 inserted into the eccentric shaft member 62, the connecting member 63, and the positioning member 64 is expanded to expand the main shaft member 61, the eccentric shaft member 62, the connecting member 63, and the positioning member 64 with respect to the basic shaft member 67. Is fixed.

  That is, in the third embodiment, when assembling the control shaft 51, the eccentric sleeve 20 can be pre-pressed into the eccentric shaft member 62 in advance, and the eccentric sleeve 20 is pre-pressed into the eccentric shaft member 62. In this case, it is not necessary to move the eccentric sleeve 20 in the axial direction of the control shaft 51 from the end of the control shaft 51 to the predetermined eccentric shaft portion 53, so that the design freedom of the control shaft 51 can be improved.

  Specifically, even if the outer diameter of the eccentric shaft portion 53 is larger than the outer diameter of the main shaft portion 52, if the eccentric sleeve 20 is press-fitted into the eccentric shaft member 62 in advance, from the end of the control shaft 51. Since it is not necessary to move the eccentric sleeve 20 in the axial direction of the control shaft 51 to the predetermined eccentric shaft portion 53, the outer diameter of the eccentric shaft portion 53 is set larger than the outer diameter of the main shaft portion 52, or the eccentric shaft portion 53. It is also possible to set the outer diameter of the main shaft portion 52 to the same diameter. Therefore, the outer diameter of the main shaft portion 52 that supports the control shaft 51 can be increased, and the strength of the main shaft portion 52 can be improved.

  Further, if the eccentric sleeve 20 is pre-pressed into the eccentric shaft member 62, the outer diameter of the eccentric shaft portion 53 located on the end side of the control shaft 51 is made smaller (compared to the outer diameter of the eccentric shaft portion 53b). The eccentric sleeve 53a has a small outer diameter), and the eccentric sleeve 20 that is press-fitted into the eccentric shaft portion 53 located on the end side of the control shaft 51 does not need to be set to have a smaller inner diameter. The eccentric sleeve 20 can be used, the degree of freedom in designing the eccentric sleeve 20 is improved, and it is not necessary to prepare the eccentric sleeve 20 having a different inner diameter. By reducing the types of the eccentric sleeve 20, the manufacturing cost is reduced. be able to. Furthermore, even if the eccentric sleeve 20 having the same size is used, the eccentric sleeve 20 is press-fitted into the eccentric shaft member 62 in advance, so that the eccentric sleeve 20 is press-fitted into the predetermined eccentric shaft portion 53. Since it does not pass through the eccentric shaft portion 53 on the end portion side, the inner peripheral surface 23 of the cylindrical portion 21 of the eccentric sleeve 20 is damaged when the eccentric shaft portion 53 on the end portion side of the control shaft 51 is passed. There is nothing.

  If the eccentric sleeve 20 is press-fitted into the eccentric shaft member 62 in advance, the interval between the main shaft portion 52 and the eccentric shaft portion 53 adjacent thereto is set larger than the length along the axial direction of the eccentric sleeve 20. Since there is no necessity, it becomes possible to increase the length of the main shaft portion 52 and the eccentric shaft portion 53 along the axial direction of the control shaft 51. Therefore, the bearing width of the main shaft portion 52 and the eccentric shaft portion 53 can be increased, and when the load acts on the main shaft portion 52 and the eccentric shaft portion 53, the main shaft portion 52 and the eccentric shaft portion 53 can be prevented from falling. Since the surface pressure in the main shaft portion 52 and the eccentric shaft portion 53 can be reduced, the bearing performance in the main shaft portion 52 and the eccentric shaft portion 53 can be improved.

  Further, if the eccentric sleeve 20 is previously press-fitted into the eccentric shaft member 62, the eccentric sleeve 20 is moved in the axial direction of the control shaft 51 from the end of the control shaft 71 to the predetermined eccentric shaft portion 53, and then the eccentric shaft. Compared with the case of press-fitting into the portion 53, press-fitting workability of the eccentric sleeve 20 can be improved. That is, the eccentric sleeve 20 is not press-fitted into the long control shaft 51, but the eccentric sleeve 20 is press-fitted into the eccentric shaft member 62, so that the press-fitting workability of the eccentric sleeve 20 can be improved. it can.

  In the control shaft 51 of the third embodiment, the eccentric sleeve 32 of the second embodiment described above can be used instead of the eccentric sleeve 20.

DESCRIPTION OF SYMBOLS 5 ... Control link 6 ... Control shaft 7 ... Eccentric shaft part 20 ... Eccentric sleeve 21 ... Cylindrical part 22 ... Rotation angle adjustment part 23 ... Inner peripheral surface 25 ... Outer peripheral surface

Claims (13)

A control having a plurality of link members for connecting pistons and crankshafts of an internal combustion engine, a control link for restricting movement of the plurality of link members, and an eccentric shaft portion to which one end of the control link is swingably connected A multi-link type piston-crank mechanism for an internal combustion engine in which the position of the eccentric shaft portion is changed by the rotation of the control shaft and the top dead center position of the piston is changed to change the compression ratio. In
A cylindrical eccentric sleeve press-fitted into the eccentric shaft portion;
A multi-link piston-crank mechanism for an internal combustion engine, wherein the top dead center position of each piston can be adjusted for each cylinder by rotating the eccentric sleeve relative to the eccentric shaft portion. On the outer periphery of the eccentric sleeve, a rotation angle adjusting portion that is engaged with a jig when the eccentric sleeve is rotated with respect to the eccentric shaft portion is formed,
2. The multi-link piston for an internal combustion engine according to claim 1, wherein the eccentric sleeve can be rotated with respect to the eccentric shaft portion in a state where the eccentric sleeve is press-fitted into the eccentric shaft portion. -Crank mechanism.   The static friction coefficient generated between the outer peripheral surface of the eccentric shaft portion and the inner peripheral surface of the eccentric sleeve is set to be larger than 0.01. A multi-link piston-crank mechanism for an internal combustion engine.   3. The internal combustion engine according to claim 1, further comprising fixing means for fixing the eccentric sleeve to the eccentric shaft portion by a force acting in a thrust direction of the eccentric shaft portion. Link type piston-crank mechanism.   The internal combustion engine according to any one of claims 1 to 4, wherein the eccentric sleeve is press-fitted into the eccentric shaft portion so that circumferential movement with respect to the eccentric shaft portion is restricted. Double link type piston-crank mechanism.   6. The eccentric sleeve according to claim 1, wherein the eccentric sleeve is press-fitted with respect to the eccentric shaft portion so that a circumferential movement with respect to the eccentric shaft portion is restricted by a combustion pressure acting on the piston. A double-link type piston-crank mechanism for an internal combustion engine according to any one of the above. The torque applied to the eccentric sleeve is T, the inner peripheral area of the eccentric sleeve is A, the press-fitting allowance of the eccentric sleeve to the eccentric shaft portion is δ, the radius of the outer diameter of the cylindrical portion of the eccentric sleeve is a, the eccentric sleeve The inner diameter of the cylindrical portion is b, the Poisson's ratio of the control shaft is υ _B , the Poisson's ratio of the eccentric sleeve is υ _H , the longitudinal elastic modulus of the control shaft is E _B , and the longitudinal elastic modulus of the eccentric sleeve is Assuming E _H , the expected value μe of the static friction coefficient between the inner peripheral surface of the eccentric sleeve and the outer peripheral surface of the eccentric shaft portion calculated by the following equation (1) is the actual inner peripheral surface of the eccentric sleeve. The multi-link piston-crank mechanism for an internal combustion engine according to any one of claims 1 to 6, wherein the coefficient is set smaller than a static friction coefficient between the outer peripheral surface of the eccentric shaft portion and the outer peripheral surface of the eccentric shaft portion.
[Equation 1]

  The control shaft includes a main shaft portion that is rotatably supported with respect to the internal combustion engine. The eccentric shaft portion is eccentric with respect to the main shaft portion, and the main shaft member serving as the main shaft portion and the eccentric shaft By inserting an elongated tubular basic shaft member into the eccentric shaft member to be a part and expanding the basic shaft member, the main shaft member and the eccentric shaft member are fixed to the basic shaft member. The multi-link piston-crank mechanism for an internal combustion engine according to any one of claims 1 to 7. A control shaft connected to a control link for restricting movement of a plurality of link members connecting a piston and a crankshaft of the internal combustion engine, the main shaft portion being rotatably supported by the internal combustion engine, and the control One end of the link is swingably connected, and has an eccentric shaft portion that is eccentric with respect to the main shaft portion, and the position of the eccentric shaft portion is changed by the rotation of the control shaft. In the control shaft of the multi-link piston-crank mechanism that changes the dead center position and changes the compression ratio of the internal combustion engine,
By rotating the eccentric shaft portion with respect to the eccentric shaft portion, a cylindrical eccentric sleeve capable of adjusting the top dead center position of the piston for each cylinder is press-fitted,
The control shaft inserts an elongated tubular basic shaft member into a main shaft member serving as the main shaft portion and an eccentric shaft member serving as the eccentric shaft portion, and expands the basic shaft member so that the basic shaft member is expanded. A control shaft for a multi-link piston-crank mechanism, wherein the main shaft member and the eccentric shaft member are fixed.   10. A multi-link piston-crank mechanism or a multi-link piston for an internal combustion engine according to claim 8, wherein an outer diameter of the main shaft portion is set to be equal to or larger than an outer diameter of the eccentric shaft portion. -The control shaft of the crank mechanism. The control shaft has a configuration in which the main shaft portion and the eccentric shaft portion are provided alternately along the axial direction,
The distance between the main shaft portion and the eccentric shaft portion adjacent to the main shaft portion is set to be shorter than the length along the axial direction of the eccentric sleeve. The control shaft of the multi-link piston-crank mechanism or the multi-link piston-crank mechanism of the internal combustion engine described.   The multi-link piston-crank mechanism for an internal combustion engine according to any one of claims 8 to 11, wherein the basic shaft member is inserted into the eccentric shaft member in which the eccentric sleeve is press-fitted. Or the control shaft of a multi-link piston-crank mechanism. A control shaft to which a control link for restricting movement of a plurality of link members that connect a piston and a crankshaft of an internal combustion engine is connected, the main shaft portion being rotatably supported by the internal combustion engine, and the control link An eccentric shaft portion that is pivotably coupled to one end of the piston, and the top dead center position of the piston is changed by changing the position of the eccentric shaft portion by rotation of the control shaft. In the manufacturing method of the control shaft of the multi-link type piston-crank mechanism that changes the compression ratio,
The control shaft includes a cylindrical main shaft member constituting the main shaft portion, a circular eccentric shaft member constituting the eccentric shaft portion, and an elongated tubular basic shaft member connecting the main shaft member and the eccentric shaft member. And having
A step of press-fitting a cylindrical eccentric sleeve whose top dead center position can be adjusted for each cylinder by rotating the eccentric shaft member with respect to the eccentric shaft portion on the outer periphery of the eccentric shaft member;
Inserting the basic shaft member into the eccentric shaft member in which the main shaft member and the eccentric sleeve are press-fitted, and disposing the main shaft member and the eccentric shaft member respectively at predetermined positions of the basic shaft member;
Expanding the basic shaft member, and fixing the main shaft member and the eccentric shaft member to the basic shaft member. A method of manufacturing a control shaft for a multi-link piston-crank mechanism, comprising:

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