JP2018054041A - Bush of connecting rod - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bush capable of restricting occurrence of seizure between the bush of a connecting rod and a piston pin even in the case of an engine in which an inner pressure of a cylinder is increased.SOLUTION: A bush 40 which is provided along the inner peripheral surface of a small end hole of a connecting rod, and into which a piston pin is slidably inserted, comprises: an oil guide groove 43 which communicates with an oil guide hole 42 for introducing lube oil into the small end hole and is provided on a sliding surface with the piston pin while including a part along a circumferential direction; and a microstructure portion 44 provided in a main load portion L occupying a fixed range of the sliding surface and provided with a plurality of minute oil grooves along a first direction. An extending direction of at least a part of the oil guide groove 43 and the first direction are not parallel to each other. The oil guide groove 43 and at least a part of the minute oil grooves communicate with each other. The main load portion L includes at least a region which is a part of the sliding surface and where a load by a piston pin based on an operation of the piston in a descending stroke acts.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a bush of a connecting rod.

  Conventionally, in an internal combustion engine such as a vehicle, a piston pin is slidably inserted into both an insertion hole of a piston and a small end hole of a connecting rod, whereby the piston is swingably connected to a small end portion of the connecting rod. It has been known. In this structure, in order to prevent seizure of the sliding surface between the piston pin and the connecting rod, lubricating oil is supplied to the sliding surface to form an oil film. For example, in the connecting rod described in Patent Document 1, a large number of oil grooves are provided on the inner surface of a bush provided along the inner periphery of the connecting rod, thereby introducing lubricating oil.

Japanese Utility Model Publication No. 57-141228

  In recent years, in order to improve the fuel consumption of the engine, it is required to increase the in-cylinder pressure of the engine or to reduce the rotation speed. When the cylinder internal pressure is increased, the force to push down the piston pin increases, so the pressure of the piston pin against the inner peripheral surface of the bush provided along the inner periphery of the small end hole of the connecting rod increases, and the piston in the bush Lubricating oil is difficult to be guided to the sliding surface with the pin, and the oil film on the sliding surface may be cut and seizure may occur. In the engine, the lubricating oil is guided to the clearance between the piston pin and the bush that is generated due to the inertia of the piston, but the clearance is hardly generated by reducing the rotation of the engine.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a bush capable of suppressing the occurrence of seizure between the connecting rod bush and the piston pin even in an engine having an increased in-cylinder pressure. To do.

  A bush according to the present invention is a bush provided along an inner peripheral surface of a small end hole of a connecting rod, and a piston pin is slidably inserted therein. Lubricating oil supplied from a large end side of the connecting rod is provided. The main load occupying a certain range of the sliding surface and the oil guiding groove that is in communication with the oil guiding hole for guiding into the small end hole, including the portion along the circumferential direction on the sliding surface with the piston pin Provided with a microtexture portion provided with a plurality of micro oil grooves along the first direction, the direction in which at least a part of the oil guide groove extends and the first direction are not parallel, The oil guide groove and at least a part of the minute oil groove communicate with each other, and the main load portion is a part of the sliding surface, and is a region where a load by the piston pin based on the operation of the piston in the downward stroke is applied. At least.

  In this bush, the lubricating oil supplied from the oil guide hole is introduced along the circumferential direction of the inner peripheral surface via the oil guide groove and reaches the main load portion. Then, the lubricating oil passes through the micro oil groove of the micro texture portion and reaches the main load portion. As a result, the lubricating oil is supplied to the main load portion, which is a region where the load from the piston pin acts on the sliding surface of the bush. Therefore, even in an engine with increased in-cylinder pressure, the bush and piston pin The occurrence of seizure can be suppressed.

  Further, in the bush according to the present invention, the main load portion includes a region corresponding to a range of change in the operation direction relative to the inner peripheral surface of the bush of the piston in the downward stroke accompanying the swing of the connecting rod. Also good.

  According to this bush, the area where the load by the piston pin acts is expanded as the connecting rod swings. However, since a minute oil groove is provided over the entire area, lubricating oil can be applied. It can supply over the whole area where the load by the piston pin acts.

  In the bush according to the present invention, the cross-sectional area of the oil guide groove may be reduced toward the most central load portion in the circumferential direction of the main load portion.

  According to this bush, since the cross-sectional area of the oil guide groove becomes smaller toward the most loaded portion, the pressure of the lubricating oil passing through the oil guide groove is increased. Thereby, lubricating oil can be effectively supplied to the main load part and the most load part.

  In the bush according to the present invention, the oil guide groove may have a width on the order of 1 to 10 mm, and the micro oil groove may have a width on the order of 1 to 1000 μm on the order of micrometers.

  According to this bush, the capillary tube is provided by the fact that the pressure of the lubricating oil supplied to the micro oil groove is increased due to the difference in the cross sectional area between the oil guide groove and the micro oil groove, and that the cross section of the micro oil groove is small. Due to the phenomenon, the lubricating oil can be effectively supplied over the entire main load portion.

  In the bush according to the present invention, the first direction may be substantially orthogonal to the extending direction of the oil guide groove in the main load portion.

  According to this bush, the lubricating oil from the oil guide groove can be uniformly supplied to the fine oil groove of the microtexture portion.

  Further, in the bush according to the present invention, the oil guiding groove may be an endless groove extending along the circumferential direction so as to make one round around the axis of the bush.

  According to this bushing, the lubricating oil is effectively supplied over the entire inner circumference, and at the main load portion, the lubricating oil is effectively supplied from the oil guide groove over the entire micro oil groove of the microtextured portion. Is supplied.

  Further, in the bush according to the present invention, the oil guiding groove is an endless groove extending so as to make one round around the axis, and at least a part of the oil guiding groove in the main load portion is predetermined in the circumferential direction. It is good also as extending at an angle.

  According to this bush, since the oil guide groove in the main load portion extends at a predetermined angle with respect to the circumferential direction of the piston pin and the bush, the range in which the oil guide groove slides is the axial direction of the piston pin. Will have a width. Thus, the lubricating oil is more effectively supplied over the entire surface of the main load portion as the piston pin rotates.

  In the bush according to the present invention, the oil guide groove has an end portion in the main load portion, and at least a part of the oil guide groove in the main load portion extends at a predetermined angle with respect to the circumferential direction. It is good to be.

  According to this bush, since the oil guide groove in the main load portion extends at a predetermined angle with respect to the circumferential direction of the piston pin and the bush, the range in which the oil guide groove slides has a width in the axial direction. Will have. Thus, the lubricating oil is more effectively supplied over the entire surface of the main load portion as the piston pin rotates. In addition, the lubricating oil is more reliably supplied to the minute oil groove communicated with the oil guide groove at two locations.

  In the bush according to the present invention, the oil guide groove includes a main oil groove including a portion along the circumferential direction, and a parallel oil groove. The parallel oil groove communicates with the main oil groove, and the circumferential direction A pair is provided in the vicinity of both ends in the circumferential direction of the main load portion, and both ends of the parallel oil groove do not reach one end and the other end of the opening edge of the bush, and the cross-sectional area of the parallel oil groove May be equal to or less than the cross-sectional area at the communicating portion of the oil guide groove with the parallel oil groove.

  According to this bush, the parallel oil groove extending in the direction intersecting the circumferential direction is provided, and the cross-sectional area of the parallel oil groove is equal to or less than the cross-sectional area of the communicating portion with the parallel oil groove in the oil guide groove. The pressure does not decrease as it advances from the oil guide groove to the parallel oil groove. Therefore, the lubricating oil is effectively supplied over the axial direction of the bush. Since the parallel oil grooves are provided in the vicinity of both ends in the circumferential direction of the main load portion, the lubricating oil can be effectively supplied from the both ends in the circumferential direction of the main load portion to the fine oil grooves in the microtexture portion. Moreover, since the parallel oil groove does not reach the opening edge of the bush, the lubricating oil does not leak excessively.

  ADVANTAGE OF THE INVENTION According to this invention, even if it is an engine in which the cylinder pressure was raised, the bush which can suppress generation | occurrence | production of seizing with the bush of a connecting rod and a piston pin can be provided.

It is sectional drawing which shows the structure of a part of engine provided with the bush concerning one Embodiment of this invention, Comprising: It is sectional drawing which shows a piston, a connecting rod, and a piston pin. It is a figure which shows a connecting rod, (a) is a side view, (b) is the BB sectional drawing of (a). It is a figure which shows the 1st example of the bush of this embodiment, Comprising: It is an expanded view which shows a part of inner surface of a bush. It is a perspective view which shows a micro texture part. It is a figure which shows the 2nd example of the bush of this embodiment, Comprising: It is an expanded view which shows a part of inner surface of a bush. It is a figure which shows the 3rd example of the bush of this embodiment, Comprising: It is an expanded view which shows a part of inner surface of a bush. It is a figure which shows the 4th example of the bush of this embodiment, Comprising: It is an expanded view which shows a part of inner surface of a bush.

  Hereinafter, embodiments according to the present invention will be described in detail with reference to the drawings. In the following description, the same or equivalent elements will be denoted by the same reference numerals, and redundant description will be omitted. In the present specification, directions such as “up” and “down” are for convenience based on the state shown in the drawings.

  FIG. 1 is a cross-sectional view showing a part of an engine provided with a bush according to an embodiment. Specifically, FIG. 1 is a cross-sectional view illustrating a lubricating structure 1 including a piston, a connecting rod, and a piston pin. 2A and 2B are diagrams showing a connecting rod, in which FIG. 2A is a side view and FIG. 2B is a cross-sectional view taken along line BB in FIG. Drawing 3 is a figure showing the 1st example of the bush of this embodiment, and is a development view showing a part of the inner side of a bush. The lubrication structure 1 is provided in an internal combustion engine such as a gasoline engine or a diesel engine. The lubrication structure 1 includes a piston 10, a connecting rod 20, and a piston pin 30.

  The piston 10 is a member that reciprocates in a cylinder of the internal combustion engine. The piston 10 is made of metal and is made of, for example, an aluminum alloy. The piston 10 has a substantially cylindrical outer shape, for example. The piston 10 has at least a head part 12 positioned on the top side and a pin boss part 14 projecting downward from the head part 12.

  A cavity 16 constituting the bottom surface of the combustion chamber is formed on the top surface of the head portion 12. A pair of pin bosses 14 are provided so as to face each other. Each of the pin boss portions 14 is formed with an insertion hole 18 having a circular cross section. A piston pin 30 is slidably inserted into the insertion hole 18. A connecting rod housing recess 19 that is recessed upward is formed between the pair of pin boss portions 14 on the lower side of the head portion 12. The connecting rod housing recess 19 houses the small end 22 of the connecting rod 20.

  The connecting rod 20 is a member that connects the piston 10 and a crankshaft (not shown) and converts the reciprocating motion of the piston 10 into the rotational motion of the crankshaft. The connecting rod 20 is made of metal, and is formed of, for example, steel. The connecting rod 20 has, for example, a rod shape. The connecting rod 20 has a small end portion 22 formed on one end side and a large end portion (not shown) formed on the other end side. The small end portion 22 has a tapered shape. The small end portion 22 is formed with a small end hole 24 having a circular cross section extending in the extending direction of the insertion hole 18 (the axial direction PD of the piston pin 30). A piston pin 30 is slidably inserted into the small end hole 24. A large end hole is formed in the large end portion, and the crankshaft is connected to the large end hole. Although not shown in FIG. 1, a bush is provided along the inner peripheral surface of the small end hole 24, and the piston pin 30 is slidably inserted into the bush.

  The piston pin 30 is a member that pivotably connects the piston 10 and the small end portion 22 of the connecting rod 20. The piston pin 30 is made of metal and is formed of, for example, chrome molybdenum steel. The piston pin 30 has a rod shape having a circular outer peripheral surface, and is formed in a hollow cylindrical shape here. The piston pin 30 may be formed in a solid cylindrical shape. Both end portions of the piston pin 30 are slidably inserted into the insertion holes 18 of the piston 10. The central portion of the piston pin 30 is slidably inserted into the small end hole 24 of the connecting rod 20. That is, the piston pin 30 is rotatable around the axis in the insertion hole 18 and the small end hole 24. The axial direction PD of the piston pin 30 coincides with both the extending direction of the insertion hole 18 and the extending direction of the small end hole 24. As shown in FIG. 1, the outer diameter of the piston pin 30 is set slightly smaller than the inner diameters of the insertion hole 18 and the small end hole 24. For this reason, a slight gap (clearance) exists between the piston pin 30 and the insertion hole 18 and between the piston pin 30 and the small end hole 24.

  In the present embodiment, as shown in FIG. 2, the connecting rod 20 has a bush 40 (not shown in FIG. 1). The bush 40 is a member that is interposed between the piston pin 30 and slidably accommodates the piston pin 30. The bush 40 is formed in a hollow cylindrical shape and has an outer peripheral surface on the inner surface of the small end hole 24. It is provided along. The inner surface of the bush 40 constitutes a sliding surface with the piston pin 30. The bush 40 is made of metal, and is formed of an alloy based on copper, for example. Lubricating oil supplied from the large end side of the connecting rod 20 passes through the communication hole 28 and the oil guide hole 42 of the bush 40 and is supplied into the small end hole 24.

  As shown in FIG. 3, the bush 40 </ b> A (40) includes an oil guiding groove 43 </ b> A (43) provided including a portion along the circumferential direction on the sliding surface with the piston pin 30. The oil guide groove 43A communicates with an oil guide hole 42A (42) for guiding the lubricating oil supplied from the large end side of the connecting rod 20 into the small end hole. The axial direction PD of the piston pin 30 and the axial direction of the bush 40 correspond to the longitudinal direction shown in FIG. 3, and the circumferential direction of the piston pin 30 and the bush 40 corresponds to the lateral direction shown in FIG.

  For example, the oil guide groove 43A has a rectangular cross section. In the example shown in FIG. 3, the oil guide groove 43 </ b> A is an endless groove extending along the circumferential direction so as to make one round around the axis of the bush 40. The oil guide groove 43A has a so-called millimeter order width of 1 to 10 mm. Further, the oil guide groove 43A has a depth on the order of millimeters.

  The bush 40A (40) includes a microtexture portion 44A (44) provided with a plurality of minute oil grooves. The micro-texture portion 44A is provided in the main load portion L that occupies a certain range of the sliding surface with the piston pin 30.

  The main load portion L is a part of the inner peripheral surface of the bush 40 and a sliding surface with the piston pin 30 and includes at least a region where a load is applied by the piston pin 30 based on the operation of the piston 10 in the downward stroke. In this specification, the intake stroke and the combustion stroke of the engine are referred to as a downward stroke. The descending direction depends on the engine layout and is not limited to the direction of gravity. In the example shown in FIGS. 1 and 2, the main load portion L is located below the inner peripheral surface of the bush 40.

  More specifically, since the connecting rod 20 swings with respect to the piston, the load direction by the piston pin 30 with respect to the inner peripheral surface of the bush 40 changes with the swing. Therefore, the main load portion L includes a region corresponding to a range of change in the operation direction of the piston 10 in the downward stroke relative to the inner peripheral surface of the bush 40 as the connecting rod 20 swings. The most loaded portion Lx is a substantially central portion of the main load portion L in the circumferential direction. In the example shown in FIGS. 1 and 2, the most loaded portion Lx is located at the lowermost position on the inner peripheral surface of the bush 40.

  FIG. 4 is a perspective view showing the microtexture portion in detail. As shown in FIG. 4, the microtexture portion has a plurality of minute oil grooves V provided along the first direction D1. The plurality of minute oil grooves V are separated by the protrusion M. The width W of the minute oil groove V is a so-called micrometer order and is, for example, 1 to 1000 μm. Further, the depth T of the minute oil groove V is also in the order of 1 to 1000 μm, for example.

  The microtexture portion 44 is provided so that the direction in which the oil guide groove 43 extends and the first direction D1 are not parallel. That is, the oil guide groove 43 and the micro oil groove V of the microtexture portion 44 intersect at least partially and communicate with each other.

  In the example shown in FIG. 3, specifically, the microtexture portion 44A is provided such that the first direction D1 that is the extending direction of the minute oil groove V is along the direction rA in FIG. That is, the first direction D1 that is the extending direction of the minute oil groove V is substantially orthogonal to the extending direction of the oil guiding groove 43A in the main load portion L.

  As shown in FIG. 3, the cross-sectional area of the oil guiding groove 43 </ b> A (43) is provided so as to decrease toward the maximum load portion Lx. Thus, the pressure of the lubricating oil passing through the oil guide groove 43 is increased toward the maximum load portion Lx by decreasing the cross-sectional area of the oil guide groove 43 toward the maximum load portion Lx.

  In the bush 40 of this embodiment, the lubricating oil supplied from the oil guide hole 42 is introduced along the circumferential direction of the inner peripheral surface via the oil guide groove 43 and reaches the main load portion L. Then, the lubricating oil reaches the main load portion L through the micro oil groove V of the micro texture portion 44. As a result, the lubricating oil is supplied to the main load portion L, which is a region where the load from the piston pin 30 acts on the sliding surface of the bush 40. Therefore, even in an engine with an increased in-cylinder pressure, the bush The occurrence of seizure between 40 and the piston pin 30 can be suppressed.

  Further, the region where the load by the piston pin 30 acts is expanded as the connecting rod 20 swings. However, according to the bush 40 of the present embodiment, the minute oil groove V is provided over the entire region. Therefore, the lubricating oil can be supplied over the entire region where the load by the piston pin 30 acts.

  Moreover, in the bush 40 of this embodiment, since the cross-sectional area of the oil guide groove 43 becomes smaller toward the most loaded portion, the surface pressure with the piston pin 30 with respect to the bush 40 is high, and the clearance between them is extremely small. Even under such circumstances, the lubricating oil can be effectively supplied to the main load portion L and the maximum load portion Lx.

  Further, since the oil guide groove 43 has a width on the order of millimeters and the minute oil groove V has a width on the order of micrometers, in the bush 40 of this embodiment, the oil guide groove 43 and the minute oil groove V are disconnected. The difference in area becomes very large. As a result, the pressure of the lubricating oil supplied to the fine oil groove is increased, and the lubricating oil is effectively effectively applied to the entire main load portion L due to the capillary phenomenon due to the small cross-sectional area of the fine oil groove. Can supply.

  Further, in the bush 40A shown in FIG. 3, the first direction D1, which is the extending direction of the minute oil groove V, is provided so as to be substantially orthogonal to the extending direction of the oil guiding groove 43A in the main load portion L. Therefore, the lubricating oil from the oil guide groove 43A can be uniformly supplied to the micro oil groove V of the microtexture portion 44A. Further, in the bush 40A shown in FIG. 3, since the oil guide groove 43A is an endless groove extending along the circumferential direction so as to make one round around the axis of the bush 40A, the effect over the entire inner circumference of the bush 40A. In the main load portion L, the lubricating oil is effectively supplied from the oil guide groove 43A over the entire micro oil groove V of the microtexture portion 44A.

  FIG. 5 is a diagram showing a second example of the bush of the present embodiment, and is a development view showing a part of the inner surface of the bush. As shown in FIG. 5, the bush 40 </ b> B (40) includes an oil guiding groove 43 </ b> B (43) provided including a portion along the circumferential direction on the sliding surface with the piston pin 30.

  Similar to the bush 40A shown in FIG. 3, the oil guide groove 43B is provided so that its cross-sectional area becomes smaller toward the maximum load portion Lx. As described above, the pressure of the lubricating oil passing through the oil guide groove 43B is increased toward the maximum load portion Lx by decreasing the cross-sectional area of the oil guide groove 43B toward the maximum load portion Lx. Can effectively supply lubricating oil.

  Further, at least a part of the oil guide groove 43B extends to the main load portion L at a predetermined angle θB with respect to the circumferential direction of the inner peripheral surface of the bush 40B. Thus, by providing the oil guide groove 43B, the range in which the oil guide groove 43B slides has a width with respect to the axial direction of the piston pin. Thereby, it becomes easy to supply lubricating oil more effectively over the whole surface of the main load part L with rotation of a piston pin.

  Further, the micro-texture portion 44B (44) of the bush 40B is provided such that the first direction D1, which is the direction of the minute oil groove V, is along a direction rB substantially orthogonal to the oil guide groove 43B in the main load portion L. ing. Thereby, lubricating oil can be uniformly supplied to the minute oil groove V from the communication part with the oil guide groove 43B. The minute oil groove V may be provided along the axial direction of the bush 40 </ b> B and the piston pin 30.

  FIG. 6 is a diagram showing a third example of the bush of the present embodiment, and is a development view showing a part of the inner surface of the bush. As shown in FIG. 6, the bush 40 </ b> C (40) includes an oil guiding groove 43 </ b> C (43) provided including a portion along the circumferential direction on the sliding surface with the piston pin 30.

  Similarly to the bush 40A shown in FIG. 3, the oil guide groove 43C is provided so that its cross-sectional area becomes smaller toward the maximum load portion Lx. Thus, since the cross-sectional area of the oil guiding groove 43C decreases toward the most loaded portion Lx, the pressure of the lubricating oil passing through the oil guiding groove 43C increases as it moves toward the most loaded portion Lx. Can effectively supply lubricating oil.

  The oil guiding groove 43C has an end portion in the main load portion L. Further, at least a part of the oil guide groove 43C in the main load portion L extends at a predetermined angle θC with respect to the circumferential direction of the inner peripheral surface of the bush 40C. Thus, by providing the oil guide groove 43B, the range in which the oil guide groove 43B slides has a width with respect to the axial direction of the piston pin. Thereby, it becomes easy to supply lubricating oil more effectively over the whole surface of the main load part L with rotation of a piston pin.

  Further, the micro-texture portion 44C (44) of the bush 40C is provided such that the first direction D1 that is the direction of the minute oil groove V is along a direction rC that is substantially orthogonal to the oil guide groove 43C in the main load portion L. ing. Thereby, lubricating oil can be uniformly supplied to the minute oil groove V from the communication part with the oil guide groove 43B.

  Further, at least a part of the minute oil groove V has two communication portions with the oil guiding groove 43C, and the lubricating oil is more reliably supplied to the minute oil groove V. The minute oil groove V may be provided along the axial direction of the bush 40C and the piston pin 30.

  FIG. 7 is a diagram showing a fourth example of the bush of the present embodiment, and is a development view showing a part of the inner surface of the bush. As shown in FIG. 7, the bush 40 </ b> D (40) includes oil guide grooves 43 </ b> D (43) and 45 </ b> D (43) on the sliding surface with the piston pin 30. The oil guide groove 43 includes a main oil groove 43D and a parallel oil groove 45D. The main oil groove 43D is provided including a portion along the circumferential direction. Like the oil guide groove 43A of the bush 40A shown in FIG. 3, the main oil groove 43D is provided so that its cross-sectional area becomes smaller toward the maximum load portion Lx. Thus, since the cross-sectional area of the main oil groove 43D becomes smaller toward the maximum load portion Lx, the pressure of the lubricating oil passing through the main oil groove 43D increases as it goes toward the maximum load portion Lx. Can effectively supply lubricating oil.

  A pair of parallel oil grooves 45D are provided so as to extend in a direction intersecting the circumferential direction. Since the parallel oil grooves 45D extend in the direction intersecting the circumferential direction, they communicate with the main oil grooves 43D extending along the circumferential direction. Further, the cross-sectional area of the parallel oil groove 45D is adjusted to be equal to or smaller than the cross-sectional area of the main oil groove 43D at the communication portion with the parallel oil groove 45D. Thereby, the pressure of the lubricating oil does not decrease as it proceeds from the main oil groove 43D to the parallel oil groove 45D. Accordingly, the lubricating oil is effectively supplied in the main load portion L in the axial direction.

  Further, the parallel oil grooves 45D are provided so that both ends thereof do not reach one end and the other end of the opening edge of the bush 40D. Accordingly, excessive leakage of the lubricating oil from the opening edge of the bush 40D is prevented.

  The parallel oil grooves 45D are provided in the vicinity of both ends in the circumferential direction of the main load portion L. Accordingly, the microtexture portion 44D (44) is positioned between the pair of parallel oil grooves 45D. The microtexture portion 44D is provided such that the first direction D1 that is the direction of the minute oil groove V is along a direction rD substantially orthogonal to the parallel oil groove 45D. Thereby, lubricating oil can be uniformly supplied to the minute oil groove V from the communicating part with the parallel oil groove 45D. The direction of the minute oil groove V (first direction D1) is not limited to the direction orthogonal to the parallel oil groove 45D, and may not be parallel to the parallel oil groove 45D.

  As described above, in the bush 40 of the present embodiment, the lubricating oil supplied from the oil guide hole 42 is introduced along the circumferential direction of the inner peripheral surface via the oil guide groove 43, and is introduced into the main load portion L. To reach. Then, the lubricating oil reaches the main load portion L through the micro oil groove V of the micro texture portion 44. As a result, the lubricating oil is supplied to the main load portion L, which is a region where the load from the piston pin 30 acts on the sliding surface of the bush 40. Therefore, even in an engine with an increased in-cylinder pressure, the bush The occurrence of seizure between 40 and the piston pin 30 can be suppressed.

  The present invention has been described in detail based on the embodiments. However, the present invention is not limited to the above embodiment. The present invention can be variously modified without departing from the gist thereof.

  DESCRIPTION OF SYMBOLS 1 ... Lubrication structure, 10 ... Piston, 12 ... Head part, 14 ... Pin boss part, 16 ... Cavity, 18 ... Insertion hole, 19 ... Connecting rod accommodation recessed part, 20 ... Connecting rod, 22 ... Small end part, 24 ... Small end hole, 28 ... Communication hole, 30 ... Piston pin, 40, 40A, 40B, 40C, 40D ... Bush, 42, 42A ... Oil guide hole, 43, 43A, 43B, 43C ... Oil guide groove, 43D ... Main oil groove, 44, 44A, 44B, 44C, 44D ... micro-texture portion, 45D ... parallel oil groove, L ... main load portion, Lx ... maximum load portion, V ... minute oil groove.

Claims (4)

A bush provided along the inner peripheral surface of the small end hole of the connecting rod, into which a piston pin is slidably inserted,
The connecting rod communicates with an oil guide hole for guiding the lubricating oil supplied from the large end side of the connecting rod into the small end hole, and is provided including a portion along the circumferential direction on the sliding surface with the piston pin Oil guide groove,
A micro-texture portion provided in a main load portion occupying a certain range of the sliding surface, and provided with a plurality of minute oil grooves along a first direction,
The direction in which at least a part of the oil guide groove extends is not parallel to the first direction,
The oil guide groove communicates with at least a part of the minute oil groove,
The main load portion is a part of the sliding surface, and includes at least a region where a load is applied by a piston pin based on the operation of the piston in the downward stroke.
bush. The main load portion includes a region corresponding to a change range of a movement direction relative to an inner peripheral surface of the bush of a piston in a downward stroke accompanying swinging of the connecting rod.
The bush according to claim 1.   3. The bush according to claim 1, wherein a cross-sectional area of the oil guide groove decreases toward a most central load portion in a circumferential direction of the main load portions. The oil guide groove has a width of the order of 1 to 10 mm,
The fine oil groove has a width of micrometer order of 1-1000 μm,
The bush as described in any one of Claims 1-3.

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