JPH0674237A - Bearing structure for internal cobustion engine - Google Patents

Abstract

PURPOSE:To prevent the occurrence of fretting abrasion between the large end parts of a connecting rod and the outer peripheral surface of a bearing metal. CONSTITUTION:Large end holes 17 are provided on the large end parts 15 of a connecting rod 13, and here, connecting rod metals 18 and 19 are engaged. The crank pin of a crank shaft is supported by the connecting rod metals 18 and 19. Communicating holes 28, guiding lubricating oil supplied from the crank pin side to the connecting rod metals 18 and 19 and the engaged parts of the large end parts 15, are provided on the connecting rod metals 18 and 19. Oil grooves 31, having a ratio of the area of them to the surface area of the large end part 15 in an engaged part of 0.1-0.4 and a width of 30-100mum, are formed on the nearly whole surface of the inner peripheral surface of the large end holes 17. Both the ends of the oil grooves 31 are opened in the axis line direction end surface 15a of the large end parts 15 in order to guide the lubrication oil, introduced into the oil grooves 31 via the communicating holes 28, outside the engaged part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bearing structure for connecting a large end portion of a connecting rod to a crankpin of a crankshaft in an internal combustion engine.

[0002]

2. Description of the Related Art Generally, in a connecting rod connected to a crankshaft of an internal combustion engine, a bearing metal (sliding bearing) is interposed between the crankpin and a large end portion which is the connecting portion. The bearing metal has a semicircular shape on the side surface and is used as a pair of upper and lower pairs. In order to improve the lubricity of the inner peripheral surface of the bearing metal on which the crankpin slides, various techniques have been conventionally proposed.

For example, in Japanese Utility Model Laid-Open No. 3-91515, as shown in FIG. 9, a large number of striation oil grooves 52, a large number of serrated oil grooves 53, and a flat surface are formed on the inner peripheral surface of a bearing metal 51. And 54. According to this technique, the flow of the lubricating oil as shown by the arrow in the figure is generated, the oil film pressure between the crank pin and the bearing metal 51 is made substantially uniform, and the lubricity and wear resistance can be improved. Further, the serrated oil groove 53 can hold the lubricating oil and prevent seizure.

[0004]

With the recent development of high-speed, high-load engines, fretting wear between the large end of the connecting rod and the bearing metal has become a problem. Fretting wear is wear that occurs when minute vibrations are applied to a contact surface that is in macroscopically stationary contact. In this case, it is considered that slight sliding occurs between the large end of the connecting rod and the outer peripheral surface of the bearing metal, and the two adhere to each other, resulting in fretting wear. Therefore, it is necessary to prevent this fretting wear.

However, in the above-mentioned prior art, although lubricity between the crank pin and the inner peripheral surface of the bearing metal, wear resistance, etc. can be improved, no consideration is given to the prevention of the above fretting wear. Therefore, the above fretting wear is likely to occur. When fretting wear occurs, the connecting rod may be broken starting from the location where the fretting wear occurs. Such a phenomenon becomes a problem particularly in the case of a connecting rod whose rigidity is not sufficiently high due to weight reduction.

The present invention has been made in view of the above circumstances, and an object thereof is to prevent the occurrence of fretting wear between the large end portion of the connecting rod and the outer peripheral surface of the bearing metal. To provide a bearing structure for an engine.

[0007]

In order to achieve the above object, the present invention provides a large-end hole at the large-end portion of a connecting rod of an internal combustion engine, and a bearing metal is fitted into the large-end hole to enable rotation. In a bearing structure of an internal combustion engine in which a crankpin of a crankshaft provided on an inner peripheral surface of the bearing metal is supported, the inner and outer peripheral surfaces of the bearing metal communicate with each other, and the crankpin side The lubricating oil supplied from the bearing metal is provided with a through hole for guiding the same to the fitting portion of the large end portion, and at least one of the outer peripheral surface of the bearing metal and the inner peripheral surface of the large end hole is provided. On the entire surface, the area ratio of the oil groove to the surface area of the large end in the fitting portion is 0.1 to 0.4, and the width is 30 μm.
A large number of oil grooves of m to 100 μm are formed, and both ends of the oil groove are connected to the fitting portion in order to guide the lubricating oil introduced into the oil groove through the through hole to the outside of the fitting portion. It is open to the axial end.

[0008]

In the fitting portion between the large end hole of the connecting rod and the bearing metal, they are macroscopically in contact with each other in a static state, and a minute vibration is applied to the contact surface as the crankshaft rotates. Fretting wear may occur due to this vibration.

However, when the crankshaft rotates,
The lubricating oil supplied from the crankpin side passes through the through hole of the bearing metal and is guided to the bearing metal and the fitting portion of the large end portion. The lubricating oil passes through an oil groove formed on one of the outer peripheral surface of the bearing metal and the inner peripheral surface of the large end hole and is led out to the outside from the axial end portion of the fitting portion. Since the oil groove is formed on almost the entire outer peripheral surface of the bearing metal or the inner peripheral surface of the large end portion, the lubricating oil is evenly distributed to the fitting portion. Therefore, the lubricating oil always flows through the fitting portion. This lubricating oil prevents direct contact between the bearing metal and the large end.

Here, from the viewpoint of suppressing fretting wear, the area ratio of the oil groove to the surface area of the large end in the fitting portion is 0.1 to 0.4, and the width of the oil groove is 30 μm. It should be ˜100 μm.

If the area ratio is less than 0.1, a sufficient amount of lubricating oil is not supplied from the oil groove to the fitting portion, and the frequency of fretting wear and the amount of wear increase rapidly. On the contrary, when the area ratio exceeds 0.4, the contact area between the bearing metal and the large end portion becomes small. As a result, the frequency of fretting wear can be reduced, but the surface pressure becomes high, and the wear of the bearing metal and the large end portion increases.

If the width of the oil groove is less than 30 μm, foreign matter in the lubricating oil will clog the oil groove, and this foreign matter will hinder the circulation of the lubricating oil. On the contrary, if the width of the oil groove exceeds 100 μm, a sufficient amount of lubricating oil cannot be supplied to the portion of the large end of the connecting rod that bears the load.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment embodying the present invention will now be described with reference to FIGS.
It will be described with reference to FIG. As shown in FIG. 2, a crankshaft 1 is arranged in the internal combustion engine. The crankshaft 1 has a crank journal 2 and a crank pin 3
And a crank arm 4 connecting the two and 3, and a counterweight 5 for balancing the rotation. The crank journal 2 is rotatably attached to a cylinder block 7 of an internal combustion engine by a bearing cap 6. That is, side surface semicircular crankshaft metals 8 and 9 are fitted to the cylinder block 7 and the bearing cap 6, respectively, and these rotatably support the crank journal 2.

A cylinder 11 as shown in FIG. 3 is formed on the cylinder block 7 above the crankshaft 1. A piston 12 is housed in the cylinder 11 so as to be vertically reciprocable. The piston 12 and the crank pin 3 of the crank shaft 1 are connected by a connecting rod 13.

The connecting rod 13 has a small end 14 and a large end 15. The small end portion 14 is connected to the piston 12 via a piston pin 16. Large end 1
5 has a large end hole 17 having a diameter slightly larger than that of the crankpin 3. The large end 15 including the large end hole 17 is vertically divided into two. Connecting rod metals 18 and 19 as bearing metals are fitted in the large end hole 17. The connecting rod metals 18 and 19 are paired up and down to form a set. Each upper and lower connecting rod metal 18, 19 is about 20m wide
The side surface is formed in a semicircular shape by a plate material of m. Then, on the outer periphery of the crank pin 3, both the upper and lower connecting rod metal 1
The large end portion 15 is externally fitted via 8 and 19. The large end 15 divided into two is fastened to each other by a pair of bolts 21. In this way, the crankshaft 1 and the piston 12 are connected by the connecting rod 13.

By the above connection, the reciprocating motion of the piston 12 in the vertical direction is transmitted to the crankshaft 1 via the connecting rod 13, and is converted into a rotational motion in the process of transmission.

As shown in FIG. 2, an oil passage 22 is provided in the cylinder block 7. One end of the oil passage 22 (Fig. 2
The upper end of the) communicates with the main oil gallery and the other end (Fig. 2).
The lower end) of the upper crankshaft metal 8 through hole 2
It communicates with 3. Then, the lubricating oil in the oil pan passes through the strainer, the oil pump, the main oil gallery, the oil passage 22 and the through hole 23 in this order, and the outer peripheral surface of the crank journal 2 and the inner peripheral surfaces of the upper and lower crankshaft metals 8 and 9 are connected. Is supplied to the gap. By this supply, an oil film is formed and lubrication is performed.

An oil passage 24 is provided inside the crankshaft 1. The oil passage 24 includes a first oil hole 25 extending in the radial direction of the crank journal 2, a second oil hole 26 extending in the radial direction of the crank pin 3, and a communication hole 27 connecting the both oil holes 25, 26. Consists of. First oil hole 2
Both ends of 5 are open to the outer peripheral surface of the crank journal 2. Further, both ends of the second oil hole 26 are connected to the crank pin 3
Has an opening on the outer peripheral surface. Therefore, a part of the lubricating oil supplied between the crank journal 2 and both the upper and lower crankshaft metals 8 and 9 is part of the first oil hole 25 and the communication hole 2.
7 and the second oil hole 26, and is guided to the gap between the crank pin 3 and the upper and lower connecting rod metals 18, 19. By introducing this lubricating oil, an oil film is formed and lubrication is performed.

As shown in FIG. 1, the upper and lower connecting rod metals 18 and 19 are provided with a plurality of through holes 28 for communicating the inner and outer peripheral surfaces thereof with each other at substantially equal angles in the circumferential direction. These through holes 28 guide the lubricating oil between the upper and lower connecting rod metals 18 and 19 and the large end portion 15 when they coincide with the opening ends of the second oil holes 26 (see FIG. 2). Further, a guide groove 29 having a width w of about 2 mm and a depth d of about 1.5 mm is formed on the outer peripheral surfaces of the upper and lower connecting rod metals 18, 19. This guide groove 29 is used for all the through holes 2 described above.
8 are connected to guide the lubricating oil introduced from the through hole 28 in the circumferential direction of the upper and lower connecting rod metals 18, 19.

Corresponding to the guide groove 29, a concave portion 30 extending in the circumferential direction is formed on the inner peripheral surface of the large end portion 15, and the lubricating oil from the guide groove 29 forms the concave portion 3.
It is temporarily stored at 0.

A large number of oil grooves 31 are formed on almost the entire inner peripheral surface of the large end hole 17. Each oil groove 31
Intersect diagonally with the axis L of the large end hole 17 and form a mesh shape as a whole. A part of the oil groove 31 crosses the recess 30. Then, both ends of the oil groove 31 have large ends 15
To the axial end surface 15a or the circumferential end surface 15b of the large end portion 15. Here, the circumferential end surface 15b is
This is a joint between the upper and lower connecting rod metals 18, 19.
At this location, there is usually a gap through which lubricating oil can flow. Therefore, if this gap is included, both ends of the oil groove 31 are open to both ends of the large end 15 in the axial direction.

As shown in FIG. 4, the oil groove 31 has a semicircular cross section. This is because if the oil groove 31 has a cross-sectional shape with a sharp bottom such as a triangular cross section, so-called edge loading is likely to occur and the strength of the large end portion 15 may be reduced.

Further, the area ratio occupied by the oil groove 31 on the inner peripheral surface of the large end hole 17 (the fitting portions of the upper and lower connecting rod metals 18, 19 and the large end portion 15) is C, and the width of the oil groove 31 is B. Then, the oil groove 31 is formed so as to satisfy the following two conditions. (1) C = 0.1 to 0.4 (2) B = 30 μm to 100 μm The above conditions are necessary to prevent fretting wear. That is, in order to prevent fretting wear, upper and lower connecting rod metals 18, 19 and the large end portion 1
The surface pressure between 5 and the amount of lubricating oil retained are important factors. Both of the above conditions are the conditions obtained by experiments from this viewpoint.

If the area ratio C is less than 0.1, a sufficient amount of lubricating oil is not supplied from the oil groove 31 between the upper and lower connecting rod metals 18 and 19 and the large end portion 15, which causes fretting wear. The occurrence rate and the amount of wear increase sharply. On the contrary,
When the area ratio C exceeds 0.4, the contact area between the upper and lower connecting rod metals 18, 19 and the large end hole 17 becomes small. As a result, although the occurrence rate of fretting wear can be suppressed, the surface pressure becomes high and the upper and lower connecting rod metal 1
The wear of 8, 19 and the large end portion 15 increases.

If the width B of the oil groove 31 is less than 30 μm, foreign matter in the lubricating oil will clog the oil groove, and this foreign matter will hinder the circulation of the lubricating oil. On the contrary, when the width B of the oil groove 31 exceeds 100 μm, the lubricating oil is not sufficiently supplied to the portion supporting the load in the large end portion 15. The load here is a force that is generated as the piston 12 moves up and down and is applied to the large end portion 15.

Further, in order to surely prevent the fretting wear, the depth N of the oil groove 31 is 30 μm to 200 μm.
It is preferably m. If the depth N is less than 30 μm, foreign matter in the lubricating oil may clog the oil groove 31, and a sufficient amount of lubricating oil may not be secured. On the contrary, the depth N is 200
If it exceeds μm, the strength of the large end 15 is suddenly reduced.

In consideration of the above points, the oil groove 3 is used in this embodiment.
The area ratio C, width B, and depth N of 1 are C = 0.2 and B = 10.
It is set to 0 μm and N = 60 μm, respectively. Next, the operation and effect of this embodiment configured as described above will be described.

The large end hole 17 of the connecting rod 13 and the upper and lower connecting rod metals 18 and 19 are macroscopically in contact with each other in a static state, and a minute vibration is applied to the contact surface as the crankshaft 1 rotates. . Fretting wear may occur due to this vibration.

However, as shown in FIG. 5, when the through holes 28 of the upper and lower connecting rod metals 18 and 19 coincide with the open ends of the second oil holes 26 of the crankshaft 1, the lubrication pressurized by the oil pump is performed. Oil is supplied to the outer peripheral surface sides of the upper and lower connecting rod metals 18, 19 through the through holes 28. This lubricating oil is guided in the circumferential direction of both the upper and lower connecting rod metals 18, 19 through the guide groove 29 and is temporarily stored in the recess 30. The lubricating oil in the recess 30 is guided to the oil groove 31 formed on the inner peripheral surface of the large end hole 17.

Here, unless both ends of the oil groove 31 are opened to the axial end surface 15a of the large end portion 15, the lubrication supplied to the fitting portion between the upper and lower connecting rod metals 18, 19 and the large end portion 15 is performed. Oil does not flow out from the mating part. As a result, the lubricating oil becomes hot and becomes sludge, which reduces the lubricating action and causes fretting wear.

On the other hand, in this embodiment, since both ends of the oil groove 31 are open to the axial end surface 15a, the lubricating oil flows along the oil groove 31, and the both ends of the oil groove 31 are vertically opened. It is led out to the outside of both connecting rod metals 18, 19. Then, the lubricating oil flows down to the oil pan. Therefore, it is possible to prevent the lubricating oil from becoming sludge and prevent the deterioration of the lubricating action.

Further, in this embodiment, since the oil groove 31 is formed on almost the entire inner peripheral surface of the large end hole 17, the upper and lower connecting rod metals 18, 19 and the large end portion 15 are fitted to each other. As described above, the lubricating oil that has entered the respective oil grooves 31 is evenly distributed. This lubricating oil receives the load generated as the piston 12 moves up and down, and lubricates between the upper and lower connecting rod metals 18, 19 and the large end portion 15. Therefore, the upper and lower connecting rod metals 18, 19 and the large end portion 1
The direct contact of No. 5 is prevented, and the occurrence of fretting wear due to the contact is suppressed.

FIG. 6 is a graph showing the relationship between the area ratio C of the oil groove 31 and the occurrence rate of fretting wear, and the relationship between the area ratio C of the oil groove 31 and the wear amount at the fitting portion. is there. The value in the graph is 100 μ when the width B of the oil groove 31 is 100 μm.
It is a value when it is set to m and the depth N of the oil groove 31 is set to 100 μm. As can be seen from FIG. 6, when the area ratio C of the oil groove 31 is in the range of 0.1 to 0.4, both the fretting wear occurrence rate and the wear amount are small. The most preferable range is the area ratio C = 0.2 to 0.3. On the other hand, when the area ratio C is smaller than 0.1, the occurrence rate of fretting wear and the wear amount increase rapidly. The oil groove 31 is provided between the upper and lower connecting rod metals 18, 19 and the large end portion 15.
This is because a sufficient amount of lubricating oil is not supplied from. vice versa,
When the area ratio C of the oil groove 31 exceeds 0.4, the occurrence rate of fretting wear decreases but the wear amount increases.
This is the upper and lower connecting rod metal 18, 19 and the large end hole 1
This is because the contact area with 7 is small and the surface pressure is high.

Next, in order to confirm the effect of preventing fretting by the oil groove 31, the following test was carried out and the area ratio of fretting wear was measured. The generated area ratio here is a ratio of a portion (area) where fretting wear occurs to the surface area of the large end portion in the fitting portion of the connecting rod metal and the large end portion. This test was conducted on the example and the comparative example. In the embodiment, the oil groove 31 described above is formed in the large end portion 15 of the connecting rod 13. In the comparative example, no oil groove is formed on either the large end hole of the connecting rod or the outer peripheral surface of the connecting rod metal.

In the test, as shown in FIG.
The test tank 34 in which the lubricating oil 35 of 5W-30 was stored was used. A connecting rod metal 33 was attached to the large end portion 32a of the connecting rod 32, a pin 36 having an oil passage 40 was inserted into the connecting rod metal 33, and lower grippers 37 were attached to both ends thereof. Similarly, the pin 38 was inserted through the small end 32b of the connecting rod 32, and the upper gripper 39 was attached to both ends thereof. The large end 32a of the connecting rod 32, the pin 36, and the lower gripper 37 were immersed in the lubricating oil 35.

Then, the upper and lower gripping machines 39, 37 were moved up and down to apply a tensile load of 2 tons and a compressive load of 4 tons to the connecting rod 13 alternately. here,
Given that the application of tensile load and the application of compressive load are one cycle, in this test, at a rate of 15 cycles per second,
× 10 ⁶ cycles were repeated for tension and compression. Furthermore, the temperature of the lubricating oil of the internal combustion engine is about 130 ° C. at maximum under normal conditions, and the connecting rod metal 33 and the large end portion 32a are
It becomes about 150 ° C at the fitting part with. From this point, in the test, the lubricating oil 35 in the test tank 34 is heated to
When the temperature of 5 reached 150 ° C, the oil pump 4
1 was operated to supply the lubricating oil 35 at 150 ° C. from the oil passage 40 between the connecting rod metal 33 and the large end portion 32a.

As a result of the above test, in the comparative example having no oil groove,
While the fretting wear occurrence area ratio was 0.7, the same occurrence area ratio decreased to 0.06 in the example. The reason for this decrease is that in the embodiment, the large end 32 is
The lubricating oil is supplied between a and the connecting rod metal 33,
It is considered that adhesion was prevented. . According to the experiment,
In the connecting rod 32, fretting wear is likely to occur in the range of 30 to 45 ° with respect to the line connecting the large end 32a and the small end 32b. From this,
It is considered that the oil grooves formed in the above range particularly contribute to the suppression of fretting wear.

As described above, in this embodiment, the oil groove 3 having a shape suitable for the large end 15 of the connecting rod 13 is formed.
Since No. 1 is provided, it is possible to effectively prevent fretting wear from occurring between the large end hole 17 and the upper and lower connecting rod metals 18 and 19. Along with this, the durability and reliability of the internal combustion engine can be greatly improved.

The present invention is not limited to the configuration of the above-mentioned embodiment, and may be arbitrarily modified within the scope not departing from the spirit of the invention as follows. (1) In the above embodiment, the oil groove 31 is formed in the large end hole 17 of the connecting rod 13, but the oil groove may be formed in the outer peripheral surfaces of the upper and lower connecting rod metals 18, 19. According to the experiment, the guide groove 29 of the connecting rod metal 18, 19 in the above-described embodiment is provided on the large end hole 17 side, and the same condition as the mesh oil groove 31 of the large end hole 17 in the above embodiment (area ratio C = 0. ．
When an oil groove having a width of B = 100 μm and a depth of N = 60 μm was provided in the connecting rod metal 18 and 19, the area ratio of fretting wear was 0.06. Therefore, even when the oil grooves are formed in the connecting rod metals 18 and 19, the occurrence of fretting wear can be greatly reduced as in the above-described embodiment.

(2) The oil groove 31 extends in the direction of the large end hole 17
There is no particular limitation as long as it is not in a direction orthogonal to the axis L of. For example, as shown in FIGS. 8A and 8B, all the oil grooves 31 may be parallel to each other and obliquely intersect the axis L. Further, as shown in FIG. 8C, all the oil grooves 31 may be parallel to the axis L.

[0041]

As described above in detail, according to the present invention, the bearing metal and the large end portion are fitted to each other on substantially the entire outer peripheral surface of the bearing metal or the inner peripheral surface of the large end hole. The area ratio of the oil groove to the surface area of the large end is 0.1 to
Since a large number of oil grooves having a width of 0.4 and a width of 30 μm to 100 μm were formed and both ends of the oil grooves were opened to the axial ends of the fitting portion, the large end of the connecting rod and the connecting rod were formed. It is possible to prevent fretting wear from occurring with the outer peripheral surface of the metal. Along with this, the durability and reliability of the internal combustion engine can be greatly improved.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of a connecting rod, upper and lower connecting rod metals and the like in an embodiment embodying the present invention.

FIG. 2 is a partially enlarged cross-sectional view of a crankshaft, a large end portion of a connecting rod, and the like in one embodiment.

FIG. 3 is a cross-sectional view showing a state in which a crankshaft and a piston are connected by a connecting rod in one embodiment.

FIG. 4 is a cross-sectional view taken along line DD of FIG. 5, showing a connecting portion of a connecting rod metal and a large end portion in one embodiment.

5 is an enlarged cross-sectional view taken along the line AA in FIG.

FIG. 6 is a graph showing a relationship between an oil groove area ratio and an occurrence rate of fretting wear, and a relationship between an oil groove area ratio and a wear amount at a fitting portion in one example.

FIG. 7 is a schematic configuration diagram of a test apparatus in one example.

8A, 8B, and 8C are development views showing another example of the oil groove.

FIG. 9 is a plan view of a conventional bearing metal.

[Explanation of symbols]

1 ... Crank shaft, 3 ... Crank pin, 13 ... Connecting rod, 15 ... Large end, 17 ... Large end hole, 1
8, 19 ... Connecting rod metal as bearing metal, 28
... through hole, 31 ... oil groove, B ... width of oil groove, C ... area ratio occupied by oil groove in fitting portion

Claims (1)

[Claims] 1. A large end hole is provided in a large end portion of a connecting rod of an internal combustion engine, and a bearing metal is fitted in the large end hole,
In a bearing structure of an internal combustion engine, wherein a crank pin of a rotatably provided crankshaft is supported by an inner peripheral surface of the bearing metal, the bearing metal has its inner and outer peripheral surfaces communicated with each other, and
A through hole for guiding the lubricating oil supplied from the crank pin side to the bearing metal and the fitting portion of the large end portion is provided, and either the outer peripheral surface of the bearing metal or the inner peripheral surface of the large end hole is provided. On almost one surface, the ratio of the area occupied by the oil groove to the surface area of the large end in the fitting portion is 0.1 to 0.1.
In order to form a large number of oil grooves having a width of 0.4 and a width of 30 μm to 100 μm, and further to guide the lubricating oil introduced into the oil grooves through the through holes to the outside of the fitting portion, A bearing structure for an internal combustion engine, characterized in that both ends of the oil groove are opened to axial ends of a fitting portion.