JP5086949B2 - Spherical connection structure of piston and connecting rod - Google Patents

Description

  The present invention relates to an improvement in a spherical connection structure between a piston and a connecting rod.

As a conventional spherical connection structure between a piston and a connecting rod, the spherical small end of the connecting rod is slidably held by an upper holding member and a lower holding member each having a concave spherical surface, and the upper holding member is held lower. A member that is movable in the radial direction of the piston with respect to the member and automatically aligns the axial misalignment between the spherical surface of the upper holding member and the spherical surface of the lower holding member is known (for example, see Patent Document 1). ).
JP 2006-275113 A

FIG. 3 of Patent Document 1 will be described with reference to FIG. In addition, the code | symbol was reassigned.
FIG. 7 is a cross-sectional view illustrating a conventional spherical connection structure of a piston and a connecting rod. The piston 220 includes an upper piston 221 and a lower piston 222 screwed to the lower portion of the upper piston 221. Are connected to each other through a spherical joint 215.

Specifically, the upper piston 221 is provided with a protruding portion 223 that protrudes downward on the back surface of the central portion, a screw 224 is formed below the protruding portion 223, and an upper holding member inside the protruding portion 223. A small spherical end 227 of the connecting rod 226 is applied through the H.225. Reference numeral 225 a is a concave spherical surface formed on the upper holding member 225 so as to be slidably fitted to the small end portion 227.
The upper holding member 225 is housed in a recess 228 formed in the protrusion 223 and is movable in the radial direction of the upper piston 221.

  The lower piston 222 is provided with a cylindrical portion 231 at the center, and a female screw 232 that is screwed to the male screw 224 of the upper piston 221 is formed on the upper portion of the cylindrical portion 231, and on the inner side of the cylindrical portion 231. The small end 227 of the connecting rod 226 is applied via the lower holding member 233. Reference numeral 233a denotes a concave spherical surface formed on the lower holding member 233 so as to be slidably fitted to the small end portion 227.

  A center line (axial center) extending vertically through the center of the spherical surface 225a provided on the upper holding member 225 and a central line (axial center) extending vertically through the center of the spherical surface 233a provided on the lower holding member 233 Even if an axial misalignment occurs, the upper holding member 225 is arranged so as to be movable in the radial direction with respect to the projecting portion 223. Therefore, the misalignment between the two center lines is automatically adjusted. The

In Cited Document 1, the number of processing steps and the number of parts of the upper piston 221 are increased such that a recess 228 is formed in the protrusion 223 or the upper holding member 225 is provided for automatic alignment by the upper holding member 225. Furthermore, since it is necessary to manage the gap between the recess 228 and the upper holding member 225, the cost of the piston 220 is increased.
Further, since the concave portion 228 is formed in the upper piston 221, the thickness of the central portion of the crown portion is reduced, and there is a concern that the rigidity of the upper piston 221 is reduced.

  The object of the present invention is to reduce the number of parts and processing man-hours while reducing the axial misalignment of the two concave spherical surfaces that hold the spherically shaped small ends of the connecting rods. An object of the present invention is to provide a spherical connection structure of a piston and a connecting rod that can prevent the above-described problem.

According to the first aspect of the present invention, a protrusion is provided on the back surface of the piston crown, a concave first spherical surface is provided at the bottom of the protrusion, and a spherical small end provided on the connecting rod is provided on the first spherical surface. The front end side is slidably fitted, and the concave second spherical surface provided on the holding member is slidably fitted on the large end side of the small end portion, and the abutment is in contact with the protrusion and the holding member. And a spherical connection structure of a piston and a connecting rod in which the small end portions are held by the first spherical surface and the second spherical surface by contacting the respective contact surfaces. a cylindrical positioning space having an inner diameter larger than the inner diameter of the first spherical and second spherical with a first spherical side from the contact surface extending toward the second spherical side is formed, the first spherical surface protrusion The first spherical surface is shaped to translate upward along a centerline passing through Is characterized in that to absorb the axial displacement between the first spherical surface and a second spherical direction along the contact surface.

As an action, by making the inner diameter of the position adjustment space larger than the inner diameters of the first spherical surface and the second spherical surface, a clearance between the small end portion in the direction along the contact surface and the first and second spherical surfaces is secured, the position adjusting space by such a contact surface extending from the first spherical side toward the second spherical side, the clearance between the small end portion and the first and second spherical in a direction perpendicular to the abutment surface Thus, the axial misalignment between the first spherical surface and the second spherical surface in the direction along the contact surface is absorbed, and local contact between the small end portion of the connecting rod and the first spherical surface and the second spherical surface is prevented.

Thus, since only the position adjustment space is formed in the holding member from the first spherical surface side of the projecting portion of the piston from the contact surface, the two concave spherical surfaces holding the small end portion of the connecting rod made spherical are provided. It is possible to reduce the cost of the piston while absorbing the shaft misalignment, and the rigidity of the piston does not decrease because the thickness of the crown portion of the piston is ensured.

In the invention according to claim 1, a cylindrical shape that extends from the first spherical surface side to the second spherical surface side from the contact surface between the protrusion and the holding member and has an inner diameter larger than the inner diameters of the first spherical surface and the second spherical surface. Position adjustment space is formed, and the axial misalignment between the first spherical surface and the second spherical surface in the direction along the contact surface is absorbed, so that the small misalignment caused by the axial misalignment between the first spherical surface and the second spherical surface due to a processing error or the like. Damage, seizure, and premature wear of the spherical connecting structure due to the local contact between the end and the first spherical surface and the second spherical surface can be prevented.
In addition, as compared with the conventional position adjustment technology, it is possible to reduce the number of processing steps and assembly steps of the piston, reduce the cost by increasing the number of parts, and increase the piston rigidity.

The best mode for carrying out the present invention will be described below with reference to the accompanying drawings. The drawings are viewed in the direction of the reference numerals.
FIG. 1 is a cross-sectional view of an internal combustion engine employing a spherical connection structure of a piston and a connecting rod according to the present invention. The internal combustion engine 10 is movable to a cylinder block 11 and a cylinder bore 12 provided in the cylinder block 11. The inserted piston 13, the connecting rod 16 connected to the piston 13 via a spherical joint 14, and the lower connecting portion 16 are rotatably attached to the lower portion of the cylinder block 11, and the connecting rod 16 is swingably supported by a hollow crankpin 17. And an assembly-type crankshaft 18.

  The cylinder block 11 includes a cylinder portion 21 provided at an upper portion, a cylindrical sleeve 22 fitted inside the cylinder portion 21 and formed with a cylinder bore 12, and an upper attached to the lower portion of the cylinder portion 21. It consists of a crankcase 23.

  The connecting rod 16 includes a spherical small end portion 24 connected to the piston 13, a large end portion 25 connected to the crankpin 17, and a rod portion 26 that connects each of the small end portion 24 and the large end portion 25. The large end portion 25 is connected to the crank pin 17 via a slide bearing 31.

  Here, reference numeral 32 is a counterweight provided on the crankshaft 18, 33 is a cylinder head attached to the top of the cylinder block 11 via a head gasket (not shown), 34 is an intake valve, 36 is an exhaust valve, 37 Is a combustion chamber, 38 is a lower crankcase attached with a plurality of bolts 41 to the lower part of the upper crankcase 23 to form a crankcase with the upper crankcase 23, and 42 is a plurality of bolts at the lower part of the lower crankcase 38. The oil pan attached at 44.

  FIG. 2 is a cross-sectional view of the piston and connecting rod according to the present invention, and the piston 13 includes a disc-shaped crown portion 65, a cylindrical and thick land portion 74 extending downward from the edge of the crown portion 65, and A cylindrical skirt portion 75, 75 extending further downward from the land portion 74 and thinner than the land portion 74, and a concave spherical surface 76 slidably fitted to the small end portion 24 of the connecting rod 16, and a crown portion 65 are provided. And a plurality of ribs 81 extending downward from the back surface 77 of the crown portion 65 while being passed to each of the land portion 74 and the cup-shaped support portion 78. It is a member made.

The crown portion 65 includes a crown surface 83 that forms a part of the combustion chamber 37 (see FIG. 1).
The land portion 74 includes a top land 74a, a top ring groove 74b, a second land 74c, a second ring groove 74d, a third land 74e, and an oil ring groove 74f in order from the crown surface 83 side at the edge of the crown portion 65. The top ring is fitted into the top ring groove 74b, the second ring is fitted into the second ring groove 74d, and the oil ring is fitted into the oil ring groove 74f. Reference numeral 74g denotes an oil hole penetrating from the groove bottom of the oil ring groove 74f to the inner surface 74h of the land portion 74.

  The cup-shaped support portion 78 includes a downward recess 91 that opens downward, a circular bottom recess 85 formed on the bottom surface 92 of the downward recess 91, and a spherical surface 76 formed on the bottom surface 86 of the bottom recess 85, A screw 94 is provided to be formed on the inner peripheral surface 93 of the downward recess 91.

  A holder 68 divided in two is inserted into the downward recess 91, and the upper surface 68 a of the holder 68 is brought into contact with the bottom surface 92 of the downward recess 91, and the spherical surface 67 formed on the holder 68 slides on the small end 24 of the connecting rod 16. Fits freely.

The holder 68 is held from below by a fastening member 71 in which a male screw 95 that is screw-coupled to the female screw 94 of the cup-shaped support portion 78 is formed. Reference numeral 68c denotes a lower surface of the holder 68 to which the upper surface 71a of the fastening member 71 is applied.
The fastening member 71 includes a plurality of engaging recesses 71b for turning and turning a tool on the end surface.

  The cup-shaped support part 78, the holder 68, the fastening member 71, and the small end part 24 described above are parts constituting the spherical joint 14.

  The holder 68 is prevented from rotating with respect to the cup-shaped support portion 78 by a non-rotating pin (not shown), and is provided with a guide surface (not shown) to be brought into contact with the rod portion 26 of the connecting rod 16. Is prevented from rotating with respect to the connecting rod 16.

The connecting rod 16 is a component in which a large end portion 25 (see FIG. 1) and a rod portion 26 are integrally formed, and a small end portion 24 is attached to the rod portion 26 with an embedded connecting bolt 101.
The rod portion 26 has a hollow portion 103, an oil hole 104, and a screw hole 106, the connecting bolt 101 has an oil hole 107 that communicates with the screw hole 106 of the rod portion 26, and the small end portion 24 has a screw hole. 111 and a plurality of oil holes 112, 113 extending from the screw hole 111 to the outer peripheral surface, and the hollow portion 103, oil hole 104, screw hole 106, oil hole 107, screw hole 111, screw hole 111, from the large end 25 side. Lubricating oil is sequentially supplied to the oil holes 112 and 113, and the sliding surface of the spherical joint 14, that is, between the small end 24 and the spherical surface 76 and between the small end 24 and the spherical surface 67 is lubricated.

The bottom concave portion 85 of the cup-shaped support portion 78 described above is separated from the straight line 121 orthogonal to the center line 120 extending vertically by the piston 13 and passing through the center of the spherical surface of the small end portion 24 by the height H1 on the large end portion 25 side. A portion in the range of the height H2 from the bottom surface 92 to the bottom surface 86, and a portion having an inner diameter D2 larger than the inner diameter D1 of the spherical surfaces 67 and 76 (that is, the outer diameter D1 of the small end portion 24), A gap of dimension C is provided on one side between the inner surface 87 of the bottom recess 85 and the small end 24.
Thus, the bottom recess 85 forms a space 88 surrounding the central portion of the small end 24.

  As described above, the bottom concave portion 85 has an inner diameter D larger than the inner diameter of the small diameter portion 24 of the connecting rod 16, and a height from the bottom surface 92 of the cup-shaped support portion 78 (or the upper surface 68 a of the holder 68) to the bottom surface 86. By having the height H2, a clearance in the direction along the straight line 121 and a clearance in the direction along the center line 120 can be secured between the small end portion 24 and the bottom recess 85.

  Accordingly, due to a processing error or the like, the center passes through the center of the spherical surface 67 on the holder 68 side with respect to the center line (axial center) parallel to the center line 120 of the piston 13 through the center of the spherical surface 76 on the cup-shaped support portion 78 side. Even when the center line (axial center) parallel to the line 120 does not match, it becomes possible to absorb the misalignment, and the piston 13, the small end 24, and the holder 68 can be assembled without difficulty. The small end 24 and the spherical surfaces 67 and 76 can be smoothly slid.

  Further, the bottom recess 85 is easily processed by changing the tool without changing the setup when processing the downward recess 91, the female thread 94, and the spherical surface 76 of the cup-shaped support 78 from the lower side of the piston 13. It is possible to reduce the increase in processing man-hours.

  Further, unlike the prior art, it is not necessary to provide the cup-shaped support portion 78 with a recess for movably storing the upper holding member that supports the upper portion of the small end portion 24, so that the thickness of the crown portion 65 is ensured. Therefore, the rigidity of the crown portion 65 can be increased as compared with the conventional case.

Next, the operation of the spherical connection structure of the piston 13 and the connecting rod 16 described above will be described.
FIG. 3 is a first operation diagram showing the operation of the spherical connection structure of the piston and the connecting rod according to the present invention, and the bottom half 86, that is, the first half of the method for determining the space 88 will be described in order. The drawings are simplified.
In (1), the small end portion 24 is fitted to the spherical surface 67 of the holder 68.
(2) shows a state in which the small end portion 24 is fitted to the spherical surface 67.

  In (3), when the holder 68 and the cup-shaped support portion 78 are assembled, if the spherical surface 67 on the holder 68 side and the spherical surface 76A on the cup-shaped support portion 78 side are misaligned, the small end portion 24 and the cup Will interfere with the spherical surface 76A of the support 78, and it will be difficult to assemble, and even if it is forcibly assembled, the small end 24 and the spherical surface 76A will hit locally, causing seizure and uneven wear. Occur.

  In (4), when the holder 68 and the cup-shaped support portion 78 are assembled, a center line 125 passing through the center of the spherical surface 67 on the holder 68 side and parallel to the center line 120 (see FIG. 2), and the cup-shaped support portion It is assumed that the center line 126 passing through the center of the spherical surface 76A on the 78 side and parallel to the center line 120 is shifted by a distance δ.

FIG. 4 is a second action diagram showing the action of the spherical coupling structure of the piston and the connecting rod according to the present invention, and the second half of the method for determining the bottom recess 86, that is, the space 88 will be described in order after FIG. The drawings are simplified.
In (5), in order to avoid interference between the small end portion 24 and the spherical surface 76A of the cup-shaped support portion 78, a bottom recess 85A is formed on the spherical surface 76A on the cup-shaped support portion 78 side.
As a result, interference in the interference part A (the part where the hatched part is applied) is avoided, but the interference part B (the part where the hatched part is applied) remains.

  In (6), in order to avoid interference at the interference part B, the spherical surface 76 </ b> A of the cup-shaped support part 78 is moved in parallel along the center line 126 so as to be separated from the small diameter part 24. A spherical surface 76B drawn with a solid line is obtained after moving the spherical surface 76A.

In (7), the bottom recess 85A and the spherical surface 76B are connected.
(8) shows the bottom recess 85 and the spherical surface 76 that are moved symmetrically with respect to the center line 125. Thus, the positions of the bottom recess 85 and the spherical surface 76 in the cup-shaped support 78 are determined.

FIGS. 5A to 5C are operation diagrams showing the operation of the spherical joint according to the present invention.
(A) shows the spherical surface 67 of the holder 68, the bottom recess 85, and the spherical surface 76 of the cup-shaped support portion 78.

(B) shows a state in which the small end portion 24 is arranged in the space 130 surrounded by the spherical surface 67, the bottom concave portion 86 and the spherical surface 76.
For example, when an external force (explosive force and inertial force) acts in the direction indicated by the white arrow, the small end portion 24 receives the external force while being in close contact with the spherical surface 76 of the cup-shaped support portion 78.

  In (c), when the external force (inertial force) is switched from the state of (b) to the direction indicated by the white arrow, for example, the small end portion 24 is cup-shaped support portion 78 as indicated by the arrow. The external force is received while being in close contact with the spherical surface 67 of the holder 68.

As described above, even when the bottom recess 85 is provided, when a large external force is applied, the spherical surface 76 and the small end portion 24 or the spherical surface 67 and the small end portion 24 can be fitted and reliably receive the external force.
In the figure, the relative movement distance of the small end portion 24 in the space 130 is exaggerated, but in actuality, the amount of movement described above is the amount of axial misalignment between the center line of the spherical surface 67 and the center line of the spherical surface 76. For example, when the distance is 20 μm, the amount of movement of the small end 24 in the direction along the center line is about 100 μm.

6A and 6B are schematic views showing another embodiment of the spherical connection structure of the piston and the connecting rod according to the present invention.
In the embodiment (a), a concave spherical surface 131 is formed on the bottom surface 92 of the cup-shaped support portion 78, and an upper concave portion 132 extending to the large end side of the connecting rod is formed on the upper surface 68 a of the holder 68. A concave spherical surface 134 is formed on the bottom surface 133 of the cup, and the bottom surface 92 of the cup-shaped support portion 78 and the upper surface 68a of the holder 68 are in contact with each other.
The upper concave portion 132 corresponds to the bottom concave portion 85 shown in FIG.

In the embodiment of (b), a bottom concave portion 136 extending toward the crown portion is formed on the bottom surface 92 of the cup-shaped support portion 78, and a concave spherical surface 138 is formed on the bottom surface 137 of the bottom concave portion 136. An upper concave portion 141 extending toward the large end of the connecting rod is formed, and a concave spherical surface 143 is formed on the bottom surface 142 of the upper concave portion 141, and the bottom surface 92 of the cup-shaped support portion 78 and the upper surface 68 a of the holder 68 are applied. Shows the state.
The bottom recess 136 and the top recess 141 are portions corresponding to the bottom recess 85 shown in FIG.

As shown in FIG. 2, a cup-shaped support portion 78 as a protruding portion is provided on the back surface 77 of the crown portion 65 of the piston 13, and a spherical surface as a concave first spherical surface is formed on the bottom of the cup-shaped support portion 78. 76 is provided, the tip end side of the spherical small end portion 24 provided on the connecting rod 16 is slidably fitted to the spherical surface 76, and a holding member is provided on the large end portion 25 (see FIG. 1) side of the small end portion 24. A spherical surface 67 as a concave second spherical surface provided in the holder 68 is slidably fitted, and a bottom surface 92 and an upper surface 68a are formed as contact surfaces that contact the cup-shaped support portion 78 and the holder 68. A spherical coupling structure of the piston 13 and the connecting rod 16 in which the small end portion 24 is held by the spherical surface 76 and the spherical surface 67 by abutting the respective abutting surfaces (the bottom surface 92 and the upper surface 68a). Shaped support 78 and The holder 68 has a space 88 as a columnar position adjustment space extending from the bottom surface 92 or the top surface 68a toward the spherical surface 76 and / or the spherical surface 67 and having an inner diameter D2 larger than the inner diameter D1 of the spherical surface 76 and the spherical surface 67. Since the axial displacement between the spherical surface 76 and the spherical surface 67 in the direction along the bottom surface 92 or the upper surface 68a is formed, the small end portion 24 and the spherical surface 76 due to the axial misalignment between the spherical surface 76 and the spherical surface 67 due to processing errors or the like. Damage, seizure, and premature wear of the spherical connection structure due to local contact between the small end portion 24 and the spherical surface 67 can be prevented.
In addition, as compared with the conventional position adjustment technique, it is possible to reduce the processing man-hours and assembly man-hours of the piston 13, reduce the cost by reducing the number of parts, and increase the rigidity of the piston 13.

  In the embodiment shown in FIGS. 3 and 4, the positions of the bottom recess 85 and the spherical surface 76 are determined with reference to the spherical surface 67 of the holder 68. However, the present invention is not limited to this, and the spherical surface 76 of the cup-shaped support portion 78 is used. You may determine the position of a bottom part recessed part and the spherical surface 67 on the basis.

  The spherical connection structure of the piston and the connecting rod of the present invention is suitable for an internal combustion engine.

It is sectional drawing of the internal combustion engine which employ | adopted the spherical connection structure of the piston and connecting rod which concerns on this invention. It is sectional drawing of the piston and connecting rod which concern on this invention. It is a 1st operation | movement figure which shows the effect | action of the spherical connection structure of the piston and connecting rod which concerns on this invention. It is a 2nd operation | movement figure which shows the effect | action of the spherical connection structure of the piston and connecting rod which concerns on this invention. It is an action figure which shows the effect | action of the spherical coupling which concerns on this invention. It is a schematic diagram which shows another embodiment of the spherical connection structure of the piston and connecting rod which concerns on this invention. It is sectional drawing explaining the spherical connection structure of the conventional piston and a connecting rod.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Internal combustion engine, 13 ... Piston, 16 ... Connecting rod, 24 ... Small end part, 65 ... Crown part, 67 ... 2nd spherical surface (spherical surface), 68 ... Holding member (holder), 68a, 92 ... Contact surface (upper surface) , Bottom surface), 76 ... first spherical surface (spherical surface), 77 ... back surface, 78 ... projecting portion (cup-shaped support portion), 88 ... position adjustment space (space), D1 ... inner diameter of spherical surface, D2 ... inner diameter of position adjustment space .

Claims (1)

A protrusion is integrally provided on the back surface of the piston crown, and a concave first spherical surface is provided on the bottom of the protrusion, and a tip of the spherical small end provided on the connecting rod is slidably fitted on the first spherical surface. And a concave second spherical surface provided on the holding member is slidably fitted to the large end side of the small end portion, and a contact surface that contacts the protruding portion and the holding member is formed. And a spherical coupling structure of a piston and a connecting rod in which the small end portions are held by the first spherical surface and the second spherical surface by contacting the respective contact surfaces,
Wherein the projection and the holding member, the with the first spherical side from the contact surface extending toward the second spherical end, cylindrical positioning space having an inner diameter larger than the inner diameter of the first spherical and second spherical (88) is formed , and the first spherical surface (76A ) is formed so that the first spherical surface (76A) translates upward along the center line (126) passing through the protrusion, and the contact surface (68a, 92) to absorb axial misalignment between the first spherical surface (76) and the second spherical surface (67) in the direction along
Spherical connection structure of piston and connecting rod.

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