JP2020016176A - Upper link in double-link type piston crank mechanism of internal combustion engine - Google Patents

Abstract

To lubricate a clearance between an upper-pin pin boss part 23 and an upper pin 4 by using an oil mist scattering in a crankcase.SOLUTION: A double-link type piston crank mechanism of an internal combustion engine is constituted of an upper link 3, a lower link 6 and a control link 7. The upper link 3 and the lower link 6 are connected to each other via the upper pin 4. An upper-pin pin boss part 23 to which the upper pin 4 is rotatably fit comprises three oil mist collection recesses 28A to 28C at end faces 24. The oil mist collection recesses 28A to 28C are recessed to crescent shapes, and arranged in three points in response to a moving trajectory of the upper-pin pin boss part 23 which is formed into a substantially-D shape.SELECTED DRAWING: Figure 5

Description

  The present invention relates to an upper link which is one of the components of a double-link type piston crank mechanism of an internal combustion engine, and more particularly to an improvement of a pin boss for an upper pin which is connected to a lower link.

  As a prior art in which a piston pin and a crank pin of a reciprocating internal combustion engine are connected by a double-link type piston crank mechanism, Patent Literature 1 previously proposed by the present applicant is known. The upper link is connected to the piston pin of the piston, the lower link connects the upper link to the crankpin of the crankshaft, one end is swingably supported by the engine body, and the other end is the lower link. And a control link connected to the link. The upper link and the lower link are rotatably connected to each other via an upper pin, and the control link and the lower link are rotatably connected to each other via a control pin.

  The upper link in such a double-link type piston crank mechanism has a configuration in which annular pin boss portions are provided at both ends of a rod-shaped rod, and one of the pin boss portions for the piston pin is connected to the piston pin, The other upper pin pin boss is connected to the upper pin. The upper pin is supported at both ends by a pair of lower link side pin bosses formed in a forked shape at one end of the lower link, and the upper pin pin boss of the upper link is rotatably fitted to the axial center. Combine.

  In order to lubricate the fitting portion between the upper pin pin boss portion and the upper pin, that is, the sliding surface, Patent Document 1 discloses a pin boss for the upper pin of the upper link via an oil injection hole provided in the lower link from inside the crankshaft. A configuration is disclosed in which lubricating oil is injected and supplied toward the outer peripheral surface of the portion. A concave portion is formed in the axial end surface of the pin boss portion for the upper pin so as to receive the lubricating oil injected and supplied to guide the lubricating oil to the contact surface with the upper pin. That is, at a predetermined crank angle, the lubricating oil is injected when the oil passage of the crank pin matches the oil injection hole of the lower link. You will be guided to the side.

JP-A-2006-198888

  However, in the configuration of Patent Document 1, lubrication is performed depending on lubricating oil supplied through the inside of the crankshaft. An object of the present invention is to provide lubrication between a pin boss for an upper pin and an upper pin by using oil mist scattered in a crankcase without depending on forced lubrication through the inside of a crankshaft.

  The upper link in the double-link type piston crank mechanism of the internal combustion engine according to the present invention has at least one of a pair of end faces of the upper pin pin boss portion extending in the axial direction of the upper pin along the inner peripheral edge of the upper pin pin boss portion. A crescent-shaped concave portion that collects oil mist scattered in the crankcase is formed at the location, being concave in the axial direction. These recesses are provided at a total of three places in the circumferential direction of the inner peripheral edge, that is, a central position on the rod portion side and a pair of positions obliquely below the rod portion.

  A large amount of oil mist is scattered in a crankcase in which a piston crank mechanism moves at high speed. The pin boss for the upper pin at the end of the upper link reciprocates up and down in a substantially D-shape within the crankcase. That is, after descending straight along the cylinder axis direction and reaching the bottom dead center, it rises diagonally, and further rises in the opposite direction so as to form a D-shape during the rise. , Reaches top dead center. With such a D-shaped reciprocating motion, the oil mist is effectively collected in the three concave portions on the end face of the pin boss portion for the upper pin. The collected oil mist gradually becomes large oil droplets and flows from the concave portion to the inner peripheral side of the upper pin boss portion. Thereby, the space between the upper pin and the upper pin is lubricated.

  The lubrication using the oil mist can be used in combination with another forced lubrication by supplying lubricating oil pressurized by an oil pump.

  According to the present invention, it is possible to lubricate between the upper pin and the pin boss for the upper pin using the oil mist scattered in the crankcase.

FIG. 2 is an explanatory diagram of a configuration of a multiple link type piston crank mechanism. The front view of the upper link of one Example. Explanatory drawing which shows the movement locus of the pin boss part for upper pins. Explanatory drawing which shows the behavior of the oil in the recessed part in four points in a movement locus. FIG. 3 is a front view of a pin boss for an upper pin according to the first embodiment. FIG. 3 is a perspective view of a pin boss for an upper pin according to the first embodiment. The front view of the pin boss part for the upper pins of the 2nd example. The perspective view of the pin boss part for the upper pins of the 2nd example. The front view of the pin boss part for upper pins of a 3rd example. The perspective view of the pin boss part for the upper pin of the 3rd example. FIG. 13 is an explanatory diagram showing the behavior of oil at the end of the concave portion in the third embodiment. The front view of the pin boss part for upper pins of a 4th example. The perspective view of the pin boss part for the upper pins of the 4th example.

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

  FIG. 1 shows components of a double-link type piston crank mechanism to which the present invention is applied. The double-link type piston crank mechanism itself is known from the above-mentioned Patent Document 1 and the like, and includes an upper link 3 having one end connected to a piston 1 via a piston pin 2, and an upper pin 3 connected to the other end of the upper link 3. A lower link 6 connected to the crank pin 5 of the crankshaft and a control link 7 for restricting the degree of freedom of the lower link 6. One end of the control link 7 is swingably supported by a support pin 8 on the engine body side, and the other end is connected to the lower link 6 via a control pin 9. Note that the multiple link type piston crank mechanism can be configured as a variable compression ratio mechanism by making the position of the support pin 8 variable.

  The lower link 6 has a cylindrical crankpin bearing 11 fitted to the crankpin 5 at the center, and the upper pin is located at a position substantially 180 ° opposite to each other across the crankpin bearing 11. And a control pin boss 13 are provided. The lower link 6 has a parallelogram shape close to a rhombus as a whole, and a lower link upper 6A including an upper pin pin boss portion 12 and a control pin And a lower link lower 6B including the pin boss portion 13. The lower link upper 6A and the lower link lower 6B are fastened to each other by a pair of bolts (not shown) inserted in opposite directions after the crankpin bearing 11 is fitted into the crankpin 5.

  The pin boss portion 12 for the upper pin has a bifurcated configuration so as to sandwich the upper link 3 at the central portion in the axial direction, and each of the pair of pin boss portions 12 for the upper pin for supporting both end portions of the upper pin 4 in the axial direction. , Extends along the axial end surface of the lower link 6. That is, between the pair of upper pin pin bosses 12, there is a groove (not shown) having a constant width that allows the upper link 3 to swing. Each upper pin pin boss portion 12 has a circular pin fitting hole, into which the upper pin 4 is press-fitted.

  The control pin pin boss portion 13 has basically the same configuration, and the control link 7 is combined with a groove (not shown) between the pair of control pin pin boss portions 13 forming a fork, and both ends of the control pin 9 are provided. The part is press-fitted into a pin fitting hole of the pin boss 13 for the control pin.

  FIG. 2 shows the upper link 3 that connects the lower link 6 and the piston 1. The upper link 3 is formed as one part by forging or casting of carbon steel, and is provided at a rod portion 21 having a rod shape having a rectangular cross section extending linearly, and at one end of the rod portion 21. And an annular pin boss 23 for an upper pin provided at the other end of the rod 21.

  The pin boss 22 for the piston pin is rotatably fitted to the center of the piston pin 2 whose both ends are supported by the piston 1. The piston pin 2 may be press-fitted and fixed to the piston 1 or may be rotatably supported by the piston 1 as a so-called full float type.

  The pin boss 23 for the upper pin is rotatably fitted to the center of the upper pin 4 whose both ends are supported by the pin boss 12 for the upper pin on the lower link 6 side. 5 and 6 are enlarged views showing details of the pin boss portion 23 for the upper pin. As shown in these figures, the upper pin pin boss portion 23 has a pair of end faces 24 facing the inner surface of the pair of upper pin pin boss portions 12 on the lower link 6 side in the axial direction of the upper pin 4, and the upper pin 4. An inner peripheral surface, that is, the bearing hole 25 into which the contacting bearing metal 31 is press-fitted, and an outer peripheral surface 26 continuous with the side surface of the rod portion 21 are formed in an annular shape. Here, the end surface 24 has an annular flat surface portion 24a on the inner peripheral side surrounding the bearing hole 25 and a tapered portion 24b located on the outer circumferential side of the annular flat surface portion 24a. The annular plane portion 24a is finished by machining along a plane orthogonal to the axial direction of the upper pin 4. On the other hand, the tapered portion 24b is inclined so as to recede from a plane along the annular flat portion 24a toward the outer peripheral side, and remains a rough surface by forging or the like.

  On each of the pair of end surfaces 24, oil mist collecting recesses 28 for collecting oil mist scattered in the crankcase are formed at three places in the circumferential direction. Specifically, a first oil mist collecting concave portion 28A is provided at a central position on the rod portion 21 side in a circumferential direction of an inner peripheral edge of the end surface 24 (annular flat portion 24a). A second oil mist collecting concave portion 28B and a third oil mist collecting concave portion 28C are provided at a pair of diagonally lower positions. Each of the oil mist collecting recesses 28A to 28C has a crescent shape in a front view in FIG. 5 and is formed to be concave in the axial direction.

  In other words, each of the oil mist collecting recesses 28A to 28C is defined by the contour 28a on the outer peripheral side located in the annular plane portion 24a and the bottom surface 28b basically forming a plane parallel to the annular plane portion 24a. ing. In the first embodiment shown in FIGS. 5 and 6, the outer peripheral side contour 28a has a shape along an inner peripheral edge of the end face 24, that is, an arc having a smaller radius of curvature than the radius of curvature of the bearing hole 25.

  In addition, between the three oil mist collecting concave portions 28A to 28C, a concave groove portion 29 may be provided along a radial square so that the annular flat portion 24a is discontinuous in the circumferential direction.

  In the first embodiment, all three oil mist collecting recesses 28A to 28C have the same size. That is, the shape of each contour 28a is the same, and the depth of the bottom surface 28b is also equal to each other. The second oil mist collecting concave portion 28B and the third oil mist collecting concave portion 28C are connected to the center line CL of the upper link passing through the center of the pin boss portion 23 for the upper pin and along the longitudinal direction of the rod portion 21 (in other words, And a center line passing through the center of the pin boss 23 for the upper pin and the center of the pin boss 22 for the piston pin). The first oil mist collecting recess 28A is also symmetrical with respect to the above-mentioned upper link center line CL in a crescent shape. In particular, in the first embodiment, the three oil mist collecting recesses 28A to 28C are arranged at substantially equal intervals. Therefore, when imagining a radius line at every 120 ° with respect to the upper link center line CL, Are respectively intersected with the oil mist collecting concave portions 28A to 28C.

  The oil mist collecting recesses 28A to 28C having the above-described configuration are formed, for example, by forming the basic shape of the upper link 3 by forging or the like, and then performing secondary processing together with machining of the annular flat surface portion 24a on the end surface 24. Mechanically machined. It may be secondarily processed by electric discharge machining or the like. In addition, when manufacturing the upper link 3 by forging etc., you may make it form the oil mist collection recessed part 28A-28C by a mold simultaneously.

  By providing the oil mist collecting recesses 28A to 28C at three places on the inner peripheral edge of the pin boss portion 23 for the upper pin as described above, the oil mist scattered in the crankcase is effectively collected. FIG. 3 shows the locus of movement of the pin boss 23 for the upper pin in the crankcase. In the multi-link type piston crank mechanism including the upper link 3, the lower link 6, and the control link 7, the pin boss portion 23 for the upper pin corresponding to the connecting portion between the upper link 3 and the lower link 6 is provided as shown in FIG. It reciprocates up and down so as to form a substantially D shape in the case. That is, while the descending stroke S1 from the top dead center TDC to the bottom dead center BDC is substantially linear along the cylinder axis direction, the ascending stroke S2 from the bottom dead center BDC to the top dead center TDC is It has a substantially L-shaped shape including a first section S2a that rises obliquely from the dead center BDC and a second section S2b that rises obliquely with the direction of inclination changed to the opposite side. FIG. 3 also shows the posture of the lower link 6 in each stroke.

  Basically, the first oil mist collecting concave portion 28A located at the upper center of the upper pin pin boss portion 23 contributes to the collection of oil mist in the descending stroke S1 (see positions A and B in FIG. 3). ). The second oil mist collecting recess 28B located on the right side in FIG. 5 contributes to the collection of oil mist in the first section S2a in the ascending stroke S2 (see position C in FIG. 3), and FIG. The third oil mist collecting concave portion 28C located on the left side of the drawing contributes to the collection of oil mist in the second section S2b in the ascending stroke S2 (see position D in FIG. 3). Then, the collected oil mist gradually grows into oil droplets, and is supplied to the inner peripheral side, that is, to the upper pin 4 with the movement of the pin boss portion 23 for the upper pin. This oil lubricates the contact surface between the bearing hole 25 (strictly, the inner peripheral surface of the bearing metal 31) and the upper pin 4.

  FIG. 4 illustrates the behavior of oil at positions A to D, which are representative crank angle positions in the movement trajectory of FIG. At the position A, the pin boss portion 23 for the upper pin is descending substantially straight downward, and is accelerating downward. Therefore, oil accumulates upward in the first oil mist collecting recess 28A. In the second oil mist collecting concave portion 28B and the third oil mist collecting concave portion 28C, the oil cannot follow the acceleration and is delayed, so that the second oil mist collecting concave portion 28B and the third oil mist collecting concave portion 28B The oil relatively moves upward in the mist collecting concave portion 28C, and is supplied to the inner peripheral side, that is, to the upper pin 4 side, away from the oil mist collecting concave portions 28B and 28C. The large arrow P in the figure indicates the moving direction of the pin boss 23 for the upper pin, and the small arrow O schematically indicates the behavior of the oil in each oil mist collecting recess 28.

  At the position B, the pin boss portion 23 for the upper pin is descending almost straight, but as it approaches the bottom dead center BDC, its moving speed is reduced. Therefore, in the second oil mist collecting concave portion 28B and the third oil mist collecting concave portion 28C, oil is deposited particularly on the lower portion thereof. In the first oil mist trapping recess 28A, the oil cannot follow the deceleration and tends to move away from the first oil mist trapping recess 28A. It is supplied to the inner peripheral side, that is, to the upper pin 4 side, away from the collecting recess 28A.

  At the position C, the pin boss portion 23 for the upper pin rises while accelerating diagonally upward to the left in the drawing. Therefore, oil accumulates in the second oil mist collecting recess 28B. In the first oil mist collecting concave portion 28A, oil that cannot follow the acceleration is supplied to the inner peripheral side, that is, the upper pin 4 side, away from the first oil mist collecting concave portion 28A. In the third oil mist collecting concave portion 28C, the oil moves in the third oil mist collecting concave portion 28C and is discharged along the contour 28a on the outer peripheral side. The oil discharged from the third oil mist collecting recess 28C is also supplied to the upper pin 4 side.

  At the position D, the pin boss portion 23 for the upper pin moves while decelerating rightward and obliquely upward in the drawing, so that oil accumulates in the third oil mist collecting recess 28C. In the first oil mist collecting concave portion 28A, the oil is supplied to the inner peripheral side, that is, the upper pin 4 side, away from the first oil mist collecting concave portion 28A, and the third oil mist collecting concave portion 28C is supplied with the third oil mist collecting concave portion 28C. The oil moves inside the oil mist collecting recess 28C and is discharged to the inner peripheral side along the contour 28a.

  By repeating such an operation, oil mist is effectively collected by the three oil mist collecting recesses 28A to 28C, and oil is supplied to almost the entire circumference of the upper pin 4.

  7 and 8 show a second embodiment in which the configuration of the oil mist collecting recesses 28A to 28C is partially changed. In the second embodiment, the capacity of the first oil mist collecting recess 28A located at the center position is equal to the capacity of the other second oil mist collecting recess 28B or the capacity of the third oil mist collecting recess 28C. It is bigger than that. In the illustrated example, the angle range along the circumferential direction of the crescent-shaped first oil mist collecting recess 28A is compared with the other second oil mist collecting recess 28B and the third oil mist collecting recess 28C. It is relatively large. For example, by increasing the radius of curvature of the contour 28a on the outer peripheral side of the first oil mist collecting concave portion 28A, the oil mist collecting concave portion 28A that is greatly expanded right and left is formed. The depth of the bottom surface 28b is the same as the depth of the second oil mist collecting recess 28B and the third oil mist collecting recess 28C.

  This takes into account that the stroke S1 (see FIG. 3) of depositing oil in the first oil mist collecting recess 28A is relatively longer than each of the sections S2a and S2b. That is, since the time during which oil is to be deposited on the first oil mist collecting recess 28A is longer than the other oil mist collecting recesses 28B and 28C, the volume of the first oil mist collecting recess 28A is relatively increased. Increasing the size increases the total amount of collected oil mist.

  As an alternative embodiment, by increasing the depth of the bottom surface 28b without changing the size of the crescent shape, the volume of the first oil mist collecting recess 28A can be increased. It may be larger than 28C.

  Next, FIGS. 9 and 10 show a third embodiment of the oil mist collecting recesses 28A to 28C. In the third embodiment, the shape of one end 28c of the contour 28a of the second oil mist collecting recess 28B and the third oil mist collecting recess 28C (specifically, one end on the side away from the rod 21). Has changed. The contour 28a basically has a shape along an arc having a constant radius of curvature, but at one end 28c farther from the rod portion 21, it is inclined so as to approach the radial line of the pin boss portion 23 for the upper pin. I have. For example, an R shape having a small radius of curvature is locally formed so as to approach the radius line. That is, at the other end 28 d of the contour 28 a, the contour 28 a intersects at a relatively small angle (for example, about 30 °) with respect to the tangent to the bearing hole 25, while the end 28 c on the side remote from the rod 21. In this case, the contour 28a intersects at a relatively large angle (for example, about 45 °) with respect to the tangent to the bearing hole 25.

  According to such a configuration, as shown in the explanatory view of FIG. 11, the oil that has moved through the oil mist collecting recesses 28B and 28C toward the one end 28c due to the acceleration is bent at the one end 28c. Is guided along the inner circumference. That is, as indicated by the arrow O, the oil has a larger velocity component toward the radially inner circumferential side.

  Next, FIGS. 12 and 13 show a fourth embodiment of the oil mist collecting recesses 28A to 28C. In the fourth embodiment, the depth of the bottom surface 28b gradually becomes shallow at both ends 28e and 28f of the crescent shape of the first oil mist collecting concave portion 28A located at the center, and finally becomes 0. Become. That is, both ends in the circumferential direction of the space formed as the concave portion are terminated as sharp ends. The depth of the entire bottom surface 28b may be gradually changed, or the depth of the bottom surface 28b is constant in most portions except both ends, and the depth near the both ends 28e and 28f may be small. A mode in which the depth gradually decreases may be adopted.

  By terminating both ends of the oil mist collecting concave portion 28A as sharp ends in this way, the flow of oil that wraps around to the outer peripheral side when the oil flows out of the oil mist collecting concave portion 28A is reduced. Therefore, the oil collected as oil mist can be more reliably supplied to the upper pin 4 side.

DESCRIPTION OF SYMBOLS 1 ... Piston 2 ... Piston pin 3 ... Upper link 4 ... Upper pin 5 ... Crank pin 6 ... Lower link 7 ... Control link 21 ... Rod part 23 ... Pin boss part for upper pins 24 ... End face 24a ... Annular flat part 24b ... Taper part 28A- 28C: Oil mist collecting recess 28a: Outline 28b: Bottom

Claims (6)

An upper link having one end connected to the piston via a piston pin,
A lower link connected to the other end of the upper link via an upper pin, and connected to a crankpin of the crankshaft;
A control link having one end swingably supported by the engine body and the other end connected to the lower link via a control pin;
The upper link in a double-link type piston crank mechanism of an internal combustion engine comprising:
The upper link includes an annular upper pin pin boss portion in which the upper pin is rotatably fitted at an end of the rod portion,
A crescent moon that collects oil mist scattered in the crankcase at at least three positions along the inner peripheral edge of the upper pin pin boss at least at one of a pair of end faces of the upper pin pin boss in the axial direction of the upper pin. A concave part of the shape is formed to be concave in the axial direction,
In the circumferential direction of the inner peripheral edge, these concave portions are provided at a total of three positions: a central position on the rod portion side, and a pair of positions obliquely below the rod portion. An upper link in a double-link type piston crank mechanism for an internal combustion engine.   2. An upper link in a double-link type piston crank mechanism for an internal combustion engine according to claim 1, wherein the contour on the outer peripheral side of the concave portion is along an arc having a radius of curvature smaller than the radius of curvature of the inner peripheral edge. .   The upper link in the double-link type piston crank mechanism for an internal combustion engine according to claim 1 or 2, wherein a volume of the concave portion located at the central position is larger than respective volumes of the other two concave portions.   4. The internal combustion engine according to claim 3, wherein an angular range along the circumferential direction of the concave portion located at the central position is larger than an angular range along the circumferential direction of each of the other two concave portions. Upper link in double-link type piston crank mechanism.   Each of the concave portions located diagonally downward with respect to the rod portion is such that the contour at one end of the crescent, which is on the side remote from the rod portion, is higher than the contour at the other end. The upper link in the double-link type piston crank mechanism of the internal combustion engine according to any one of claims 1 to 4, wherein the upper link is inclined so as to approach a radius line of the pin boss portion.   The internal combustion engine according to any one of claims 1 to 5, wherein, at both ends of the crescent shape of the recess located at the central position, the depth of the recess gradually decreases and ends as a sharp end. Upper link in the double-link piston crank mechanism of the engine.

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