JP2009079499A - Connecting structure of piston and connecting rod - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a connecting structure of a piston and a connecting rod capable of surely reducing slap noise and providing favorable characteristics. <P>SOLUTION: The connecting structure connects the piston 10 and the connecting rod 20 of an internal combustion engine, and is provided with a piston pin 30 inserted in the small end 21 of the connecting rod 20 and being the oscillation center of the piston 10, two shafts 50 disposed roughly in parallel at both ends of the piston pin 30 at the side of the small end 21 of the connecting rod 20 and having both ends thereof fixed to the piston 10, and a support plate 40 including a first through hole 41 through which the piston pin 30 is inserted and second insertion holes 42 which are formed at both sides of the first through hole 41 and in which the shafts 50 are fitted, respectively. The connecting rod 20 is connected to the support plate 40 via the piston rod 30, and the support plate 40 is connected to the piston 10 via the shafts 50. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a connection structure between a piston and a connecting rod of an internal combustion engine.

  In an internal combustion engine (engine), a piston is connected to a crankshaft via a connecting rod, and the piston and the connecting rod are rotatably connected by a piston pin. In general, a pair of piston pin holes are formed in the piston, and the piston pins are fitted into the piston pin holes.

  Here, a plurality of piston ring grooves into which piston rings are mounted are formed on the outer periphery of the piston. For this reason, the piston pin hole is provided below the piston ring groove on the lowermost side so as not to interfere with these piston ring grooves, and the center of the piston pin hole is the same as the radius of the piston pin hole. Furthermore, it is located on the lower end side.

  The piston of an internal combustion engine is thick because the top side faces the combustion chamber, and the weight of the piston is heavier on the top side than on the lower end side, and the center of gravity of the piston is located on the top side. is doing. In general, the center of gravity of the piston is positioned on the upper side (top surface side) of the center axis of the piston pin.

  Thus, in the conventional internal combustion engine, the center axis of the piston pin is located on the lower end side of the piston with respect to the center of gravity of the piston, that is, is in an offset state. Therefore, during engine operation, for example, there is a problem that a moment around the piston pin is generated near the piston top dead center position, and the piston collides against the cylinder wall surface to generate a slap sound.

  It is considered that such slap noise can be reduced to some extent by bringing the central axis of the piston pin closer to the center of gravity of the piston. However, in the conventional piston structure, it is difficult to bring the central axis of the piston pin close to the center of gravity of the piston due to the relationship with the piston ring groove and the like as described above.

  Various proposals have been made for the purpose of reducing the slap noise. For example, by forming an oil ring groove below the piston pin hole, the piston pin hole position (piston pin (The center axis) of the piston is close to the center of gravity of the piston (for example, see Patent Document 1).

JP-A-9-119523

  By changing the position of the oil ring groove in this way, the center axis of the piston pin can be brought close to the center of gravity of the piston, and slap noise can be reduced. However, in order to change the position of the oil ring groove, it is necessary to significantly change the structure of the piston, which may deteriorate the characteristics of the internal combustion engine and increase the cost.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a connecting structure between a piston and a connecting rod that can reliably reduce slap noise and obtain good characteristics.

  A first aspect of the present invention that solves the above-described problem is a connection structure that connects a piston and a connecting rod of an internal combustion engine, and is inserted into a small end portion of the connecting rod to become a swing center of the piston. A piston pin, two shafts arranged substantially parallel to both sides of the piston pin at the side of the small end of the connecting rod and having both ends fixed to the piston, and a first through which the piston pin is inserted And a support plate having a second through hole disposed on both sides of the first through hole and into which the shaft is inserted, and the connecting rod is supported by the piston pin through the piston pin. And the support plate is connected to the piston via the shaft. In the coupling structure between.

  In the first aspect, since the piston pin is not directly connected to the piston but connected to the shaft fixed to the piston and the support plate connected to the shaft, the position of the piston ring groove is taken care of. The position of the piston pin can be set. Accordingly, it is possible to reduce the slap noise during engine operation by bringing the center axis of the piston pin closer to the center of gravity of the piston.

  In the second aspect of the present invention, a plurality of piston ring grooves are formed on the outer periphery of the piston, and the uppermost portion of the piston pin is located on the piston more than the lower end of the piston ring groove disposed on the lowermost side. The connecting structure of the piston and the connecting rod according to claim 1, wherein the piston is connected to the connecting rod.

  In the second aspect, the center axis of the piston pin can be reliably brought close to the center of gravity of the piston.

  According to a third aspect of the present invention, the piston and connecting portion according to the first or second aspect are characterized in that the central axis of the piston pin is located on the top surface side of the piston with respect to the central axis of the shaft. It is connected to the rod.

  In the third aspect, the center axis of the piston pin can be reliably brought closer to the center of gravity of the piston.

  According to a fourth aspect of the present invention, there is provided the coupling structure of the piston and the connecting rod according to any one of the first to third aspects, wherein the shaft has a smaller diameter than the piston pin.

  In the fourth aspect, by making the shaft smaller in diameter than the piston pin, the center of the piston pin can be reliably and easily brought close to the center of gravity of the piston, which can contribute to weight reduction.

  According to a fifth aspect of the present invention, there is provided the piston and the connecting rod according to any one of the first to fourth aspects, wherein the support plate is disposed as a pair on both sides in the axial direction of the connecting rod. It is in a connected structure.

  In the fifth aspect, since the piston pin and the connecting rod are supported in a well-balanced manner by the pair of support plates, the piston and the connecting rod can be well connected through the support plate.

  In a sixth aspect of the present invention, a slit portion that divides the small end portion in the axial direction is formed in the small end portion of the connecting rod, and the support plate is disposed in the slit portion. It is in the connection structure of the piston and connecting rod of any one of the aspects 1-4.

  In the sixth aspect, the positional relationship between the support plate and the connecting rod is not displaced, and the piston and the connecting rod can be well connected via the support plate.

  In the present invention, since the degree of freedom of the arrangement position of the piston pin is increased as compared with the conventional connection structure in which the piston and the connecting rod are directly connected by the piston pin, the central axis of the piston pin is set to the head portion side (top surface side). ) Can be arranged. Therefore, the slap noise generated when the piston collides against the cylinder wall surface can be greatly reduced by bringing the center axis of the piston pin close to the center of gravity of the piston.

  Hereinafter, the present invention will be described in detail based on embodiments.

  FIG. 1 is an exploded perspective view showing a connecting structure of a piston and a connecting rod according to an embodiment of the present invention, FIG. 2 is an assembled cross-sectional view thereof, and FIG. It is sectional drawing.

  In the coupling structure of the piston and the connecting rod according to the present invention, as shown in the figure, the piston 10 of the internal combustion engine and the small end portion 21 of the connecting rod 20 are composed of the piston pin 30, the support plate 40, and the piston pin 30. Are also connected by a small-diameter shaft 50.

  The support plate 40 is composed of a plate-like member, and a first through hole 41 into which the piston pin 30 is inserted is formed at the center thereof, and the shaft 50 is formed on both sides of the first through hole 41. A second through hole 42 to be inserted is formed. In the present embodiment, the support plate 40 is disposed on both outer sides (both sides in the axial direction of the piston pin 30) of the small end portion 21 of the connecting rod 20.

  The first through-hole 41 is formed with the same inner diameter as the piston pin hole 22 provided in the small end portion 21 of the connecting rod 20, and the first through-hole 41 of the pair of support plates 40 is interposed therebetween. The piston pin 30 is inserted into the piston pin hole 22 of the connecting rod 20 that is arranged, and the support plate 40 and the connecting rod 20 are connected.

  The piston pin 30 is rotatably inserted into the small end portion 21 (piston pin hole 22) of the connecting rod 20 and serves as a swing center of the piston 10. In other words, the connecting rod 20 is connected to the support plate 40 via the piston pin 30 so as to be rotatable, and is configured such that the piston 10 can swing (turn) with respect to the connecting rod 20. Further, at both ends of the piston pin 30, a regulating member such as a clip (not shown) is provided so that the connecting rod 20 and the support plate 40 do not come off.

  As described above, the support plate 40 is formed with the second through holes 42 into which the shafts 50 are fitted on both sides of the first through holes 41. In the present embodiment, the second through hole 42 is formed such that its center 42 a is at the same height as the center 41 a of the first through hole 41, as shown in FIG. 3. That is, the central axis of the shaft 50 and the central axis of the piston pin 30 are set to have the same height. Then, the two shafts 50 are fitted into the second through holes 42 of the support plate 40 and both ends of the shaft 50 are fixed to the piston 10 so that the support plate 40 and the piston 10 are connected. Yes.

  At this time, the shaft 50 is arranged in parallel with the piston pin 30 on both sides of the piston pin 30 that is the side of the connecting rod 20. Further, the support plate 40 is disposed across the two shafts 50.

  The piston 10 is forged with, for example, an aluminum alloy, and is fixed to which a head portion 11 that mainly forms a combustion chamber in a cylinder, a skirt portion 12 provided below the head portion 11, and a shaft 50 are inserted and fixed. It is comprised from the pin boss | hub part 14 in which the hole 13 is provided. A plurality (for example, three) of piston ring grooves 15 in which piston rings (not shown) are mounted are formed on the outer peripheral surface of the head portion 11.

  As shown in FIGS. 2 and 3, the central portion of the head portion 11 is formed thinner than the outer peripheral portion, and the connecting rod 20 connected to the support plate 40 is accommodated in this portion. It has become. Further, the pin boss part 14 is formed thicker than the skirt part 12, and the fixing hole 13 is provided through the thick pin boss part 14. In the present embodiment, since the two shafts 50 are fixed to the piston 10, four fixing holes 13 (pin boss portions 14) are formed in the piston 10. These fixing holes 13 need to be provided on the lower side of the piston ring groove 15 so as not to interfere with the piston ring groove 15, but may be formed on the top surface side of the head portion 11 of the piston 10 as much as possible. preferable.

  The shaft 50 is fitted into the second through hole 42 of the support plate 40 in a state where the connecting rod 20 connected to the support plate 40 is accommodated in such a piston 10, and both ends thereof are fixed holes 13. As a result, the support plate 40 and the piston 10 are connected. That is, the connecting rod 20 and the piston 10 are connected by supporting the piston pin 30 on the support plate 40 that is passed between the two shafts 50 fixed to the piston 10. Note that both ends of the shaft 50 are fixed by clips or the like (not shown) so as not to come out of the fixing hole 13 of the piston 10.

  Thus, in the connection structure according to the present invention, the piston 10 and the connecting rod 20 are not directly connected by the piston pin 30 as in the prior art, but the piston pin 30, the support plate 40, and the shaft. 50 to be connected to each other.

  Therefore, in the connection structure according to the present invention, the piston 10 is not provided with a hole for fixing the piston pin 30, and is provided with a fixing hole 13 for fixing the shaft 50 having a smaller diameter than the piston pin 30. Yes.

  Since the diameter of the shaft 50 is smaller than the diameter of the piston pin 30, the diameter of the fixing hole 13 is naturally smaller than the diameter of the hole for supporting the piston pin provided in the conventional piston. Therefore, the center of the fixing hole 13 can be formed on the top surface side (head portion 11 side) of the piston 10 with respect to the hole for supporting the conventional piston pin. Further, since the piston pin 30 is not directly fixed to the piston 10, it is not necessary to consider the position of the piston ring groove 15, and the piston pin 30 can be arranged close to the top surface side of the piston 10. it can.

  In the present invention, the top surface of the head portion 11 is L1 above the lower end of the piston ring groove 15 in which the uppermost portion of the piston pin 30 is disposed on the lowermost end side (skirt portion 12 side) among the plurality of piston ring grooves 15. It is located on the side. Thereby, since the center axis | shaft of piston pin 30 approaches the gravity center of piston 10, the slap sound which a piston 10 collides with a cylinder wall surface can be reduced significantly.

  Although one embodiment of the present invention has been described above, the present invention is of course not limited to this embodiment. For example, in the present embodiment, the centers 41a and 42a of the first through hole 41 and the second through hole 42 formed in the support plate 40 are set to the same height, and the central axis of the piston pin 30 and the shaft 50 are Although it is formed so that the central axis has the same height, it is not limited to this. For example, as shown in FIG. 4, the center 41a of the first through hole 41 through which the piston pin 30 is inserted is more top than the center 42a of the second through hole 42 into which the shaft 50 is fitted. You may form so that it may be located in the side. Thereby, for example, even when the center of gravity of the piston is close to the top surface of the piston, the center axis of the piston pin 30 can be reliably brought close to the center of gravity of the piston 10.

  Moreover, although this embodiment demonstrated the example which arranged the support plate 40 on both the outer sides (axial direction outer side) of the small end part 21 of the connecting rod 20, the connection structure of this invention has this. It is not limited. For example, as shown in FIG. 5, a slit portion 25 that divides the small end portion in the axial direction is formed in the small end portion 21 of the connecting rod 20A, and the support plate 40A is arranged in the slit portion 25. May be. Even in such a configuration, of course, the slap noise can be suppressed as described above, and further, the position of the support plate 40A and the connecting rod 20A can be prevented from being displaced, and the connection with the piston 10 side can be kept good. In addition, since the number of parts is reduced, the cost can be reduced. In the case of this configuration, it is preferable that the thickness of the support plate 40A is greater than that of the above-described embodiment in consideration of strength.

  In the above-described configuration, the piston pin 30 is rotatably inserted into the small end portion 21 (piston pin hole 22) of the connecting rod 20, 20A, but the piston pin 30 is the first of the support plates 40, 40A. Therefore, the connecting rods 20 and 20A may be fixed to the connecting rods 20 and 20A. Of course, even in such a configuration, the piston 10 is slidably connected to the connecting rods 20 and 20A by the piston pin 30.

  Moreover, the structure of this invention demonstrated above is applicable to the connection part of the piston and connecting rod of all internal combustion engines, such as a gasoline engine and a diesel engine, for example.

It is a disassembled perspective view which shows the connection structure of the piston and connecting rod which concern on one Embodiment of this invention. It is an assembly sectional view showing the connection structure of the piston and connecting rod concerning one embodiment of the present invention. It is an assembly sectional view showing the connection structure of the piston and connecting rod concerning one embodiment of the present invention. It is an assembly sectional view showing the connection structure of the piston and connecting rod concerning one embodiment of the present invention, and is a figure showing the modification of a support plate. It is an assembly sectional view showing the modification of the connection structure of the piston and connecting rod concerning one embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Piston 11 Head part 12 Skirt part 13 Fixing hole 14 Pin boss part 15 Piston ring groove 20 Connecting rod 21 Small end part 22 Piston pin hole 25 Slit part 30 Piston pin 40 Support plate 41 1st through-hole 42 2nd through-hole 50 shaft

Claims (6)

A connecting structure for connecting a piston and a connecting rod of an internal combustion engine,
A piston pin inserted into the small end of the connecting rod and serving as a swing center of the piston;
Two shafts arranged substantially parallel to both sides of the piston pin on the side of the small end of the connecting rod and fixed at both ends to the piston;
A support plate having a first through-hole through which the piston pin is inserted and a second through-hole arranged on both sides of the first through-hole and into which the shaft is respectively fitted;
A connecting structure of a piston and a connecting rod, wherein the connecting rod is connected to a support plate via the piston pin, and the support plate is connected to the piston via the shaft.   Plural piston ring grooves are formed on the outer periphery of the piston, and the uppermost part of the piston pin is located on the top surface side of the piston with respect to the lower end of the piston ring groove disposed on the lowermost side. The connecting structure of a piston and a connecting rod according to claim 1.   The piston / connecting rod connection structure according to claim 1, wherein a central axis of the piston pin is located on a top surface side of the piston with respect to a central axis of the shaft.   The said shaft is made into the diameter smaller than the said piston pin, The connection structure of the piston and connecting rod as described in any one of Claims 1-3 characterized by the above-mentioned.   The said support plate is arrange | positioned in a pair by the axial direction both sides of the small end part of the said connecting rod, The connection structure of the piston and connecting rod as described in any one of Claims 1-4 characterized by the above-mentioned.   The slit part which divides | segments the small end part to an axial direction is formed in the small end part of the said connecting rod, The said support plate is distribute | arranged in the said slit part, Any one of Claims 1-4 characterized by the above-mentioned. A connecting structure of the piston according to claim 1 and a connecting rod.

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