JP2021095939A - Oil lubrication bearing structure - Google Patents

Abstract

To provide an oil lubrication bearing structure that can suppress slide resistance between a main journal 11 and a metal bearing 30 even when a lubrication film V with a film thickness capable of preventing shortage of oil film is interposed therebetween.SOLUTION: An oil lubrication bearing structure includes: a substantially columnar main journal 11; a metal bearing 30 for supporting the main journal 11 in a radial direction of the main journal 11; and an oil supply part 5 for supplying lubricant to a gap between the main journal 11 and the metal bearing 30. The metal bearing 30 has a slide surface formed of an oil repellent coating film 30b having oil repellency as a whole.SELECTED DRAWING: Figure 5

Description

The present invention relates to an oil-lubricated bearing structure in which a rotating shaft such as an engine crankshaft is supported by lubricating oil and a slide bearing.

As a bearing that rotatably supports the rotating shaft body, a sliding bearing having a sliding surface facing the outer peripheral surface of the rotating shaft body and a fluid bearing composed of a lubricating film interposed in a gap between the sliding bearings are known. ing.
For example, in Patent Document 1, as a fluid bearing that supports a crankshaft, which is a rotating shaft body, in a floating state, it is interposed between a slide bearing that receives a radial load along the radial direction of the crankshaft and a slide bearing. A bearing structure composed of a lubricating oil (lubricating film) is disclosed.

By the way, in Patent Document 1, when the thickness of the lubricating oil (lubricating film) is thin, the larger the radial load applied to the crankshaft, the more easily the oil film breaks. When the oil film runs out, the crankshaft and the slide bearing slide in direct contact with each other, which may cause wear of the crankshaft and the slide bearing.

Therefore, it is conceivable to increase the thickness of the lubricating oil (lubricating film), but as the film thickness increases, the shear stress of the lubricating oil increases, so the sliding resistance between the crankshaft and the slide bearing increases. There was a problem of doing.

Japanese Unexamined Patent Publication No. 2018-155381

In view of the above problems, the present invention provides oil lubrication capable of suppressing sliding resistance between the rotating shaft body and the slide bearing even when a lubricating film having a thickness capable of preventing the occurrence of oil film breakage is interposed. It is an object of the present invention to provide a bearing structure.

The present invention is an oil-lubricated bearing structure including a substantially columnar rotating shaft body and a slide bearing that supports the rotating shaft body in the radial direction of the rotating shaft body, wherein the rotating shaft body and the slide bearing are provided. The sliding surface of the rotating shaft body or the sliding surface of the slide bearing is provided with an oil supply unit that supplies lubricating oil to the gap between the two, and one of the sliding surfaces has oil repellency on the entire surface. It is characterized by being formed on an oil level.

The oil supply unit refers to a supply unit that supplies lubricating oil from the radial direction to the gap between the rotary shaft body and the slide bearing, or a supply unit that supplies lubricating oil from the axial direction of the rotary shaft body. ..
According to the present invention, it is possible to suppress the sliding resistance between the rotating shaft body and the slide bearing even when a lubricating film having a film thickness capable of preventing the occurrence of oil film breakage is interposed.

Specifically, the oil-repellent surface can separate only the oil while allowing contact with air contained in the oil. Therefore, when lubricating oil containing air is supplied to the gap between the rotating shaft body and the sliding bearing due to the relative rotation between the rotating shaft body and the slide bearing, the oil-lubricated bearing structure is contained in the lubricating oil. Lubricating oil can be separated from one sliding surface by leaving the air to be on one sliding surface side.

That is, in the oil-lubricated bearing structure, the air contained in the lubricating oil can be separated as the rotating shaft body and the slide bearing rotate relative to each other. Therefore, in the oil-lubricated bearing structure, an air supply unit is separately provided with a lubricating film composed of a thin film air layer in contact with one sliding surface which is an oil-repellent surface and an oil layer in contact with the other sliding surface. It can be formed in the gap between the rotating shaft body and the slide bearing without any problem.

As a result, the oil-lubricated bearing structure can form a lubricating film in which the film thickness of the oil layer is suppressed as compared with the case where the lubricating film is formed only with the lubricating oil, so that the shear stress of the oil layer can be suppressed.

Further, for example, when the radial load is relatively small, the oil-lubricated bearing structure supports the rotating shaft body in a floating state by the oil layer and the air layer. In this case, the oil-lubricated bearing structure can suppress the sliding resistance between the rotating shaft body and the slide bearing by the air layer having a lower viscous resistance than the lubricating oil.

Furthermore, even when the radial load is relatively large and it is difficult to maintain the air layer, the oil-lubricated bearing structure can reduce the frictional resistance between the oil layer and one of the sliding surfaces by the oil-repellent surface. , The sliding resistance between the rotating shaft body and the slide bearing can be suppressed.

Therefore, the oil-lubricated bearing structure can suppress the sliding resistance between the rotating shaft body and the slide bearing even when a lubricating film having a thickness capable of preventing the occurrence of oil film breakage is interposed.

As an aspect of the present invention, the oil discharging portion for discharging the lubricating oil interposed between the rotating shaft body and the sliding bearing is provided, and the oil supply portion is the one sliding surface which is the oil repellent surface. The oil discharge portion may be formed with an opening in the other sliding surface.

According to this configuration, the oil-lubricated bearing structure can reliably flow the lubricating oil from the oil supply unit to the oil discharge unit.
Specifically, the oil layer in contact with the other sliding surface is hindered by the oil-repellent surface and the air layer even when pressed toward one sliding surface, and the flow of the oil layer is hindered by the air layer. I can't touch.

Therefore, for example, when the oil supply portion is formed with an opening on the other sliding surface and the oil discharge portion is formed with an opening on one sliding surface which is an oil-repellent surface, the lubricating oil supplied from the oil supply portion is formed. , Cannot flow into the oil discharge section beyond the air layer.

On the other hand, since the oil supply portion is formed with an opening on one of the sliding surfaces which is the oil-repellent surface, the oil-lubricated bearing structure makes the lubricating oil supplied to the air layer relative to the rotary shaft body and the slide bearing. By the rotation and the cooperation with the oil-repellent surface, the contained air can be separated and flowed to the oil layer.

Further, since the oil discharge portion formed with an opening on the other sliding surface is in contact with the oil layer, the oil-lubricated bearing structure can smoothly discharge the lubricating oil of the oil layer to the oil discharge portion.
Therefore, in the oil-lubricated bearing structure, the lubricating oil can be reliably flowed from the oil supply portion to the oil discharge portion, and a stable lubricating film can be formed between the rotating shaft body and the slide bearing.

Further, as an aspect of the present invention, the oil-repellent surface may be formed of a fluororesin film.
According to this configuration, the oil-lubricated bearing structure can form an oil-repellent surface that exhibits higher oil repellency. Therefore, the oil-lubricated bearing structure can more reliably form a lubricating film composed of an air layer and an oil layer.
Therefore, the oil-lubricated bearing structure can surely suppress the sliding resistance between the rotating shaft body and the slide bearing.

Further, as an aspect of the present invention, the fluororesin coating may be formed of a crosslinked fluororesin.
According to this configuration, the oil-lubricated bearing structure can further improve the wear resistance of the oil-repellent surface. Therefore, the oil-lubricated bearing structure can secure an oil-repellent surface for a long period of time.
Therefore, the oil-lubricated bearing structure can suppress the sliding resistance between the rotating shaft body and the slide bearing for a long period of time.

Further, as an aspect of the present invention, the rotating shaft body may be a crankshaft of an engine.
According to this configuration, the oil-lubricated bearing structure stably suppresses sliding resistance by the cooperation between the lubricating film having an air layer and the oil-repellent surface even for a crankshaft having a large fluctuation range of the radial load. be able to.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide an oil-lubricated bearing structure capable of suppressing sliding resistance between a rotating shaft body and a slide bearing even when a lubricating film having a thickness capable of preventing the occurrence of oil film breakage is interposed. Can be done.

Sectional drawing which shows the cross section of a multi-cylinder engine. A cross-sectional view taken along the line AA in FIG. FIG. 1 is a cross-sectional view taken along the line BB in FIG. The external perspective view which shows the appearance of a metal bearing and a block oil passage. An explanatory view of the bearing structure of the main journal in the cross section taken along the line AA. Explanatory drawing of the bearing structure of the main journal in the cross section taken along the line CC in FIG. Explanatory drawing of bearing structure of pin journal in BB arrow cross section.

An embodiment of the present invention will be described below with reference to the drawings.
The oil-lubricated bearing structure of the present embodiment is a so-called fluid bearing structure in which a rotating shaft body is supported in a floating state by a lubricating film and a slide bearing. A multi-cylinder engine to which such an oil-lubricated bearing structure is applied will be described in detail with reference to FIGS. 1 to 7.

Note that FIG. 1 shows a cross-sectional view of the multi-cylinder engine 1, FIG. 2 shows a cross-sectional view taken along the line AA in FIG. 1, and FIG. 3 shows a cross-sectional view taken along the line BB in FIG. Reference numeral 4 denotes an external perspective view of the metal bearing 30 and the block oil passage 24.
Further, FIG. 5 is an explanatory view of the bearing structure of the main journal 11 in the cross section taken along the line AA, FIG. 5 (a) shows a cross section in the cross section along the radial direction, and FIG. 5 (b) is FIG. An enlarged cross-sectional view of a main part of the part D surrounded by the alternate long and short dash line in (a) is shown.

Furthermore, FIG. 6 is an explanatory view of the bearing structure of the main journal 11 in the cross section taken along the line CC in FIG. 1, and FIG. 6 (a) shows a cross section in the cross section along the radial direction. b) shows an enlarged cross-sectional view of a main part of the part E surrounded by the alternate long and short dash line in FIG. 6 (a).

In addition, FIG. 7 is an explanatory view of the bearing structure of the pin journal 12 in the cross section taken along the line BB, FIG. 7 (a) shows a cross section in the cross section along the radial direction, and FIG. 7 (b) is a view. An enlarged cross-sectional view of a main part of the F part surrounded by the alternate long and short dash line in 7 (a) is shown.
Further, the arrow X in the figure indicates a direction along the rotation center of the crankshaft 10 (hereinafter, referred to as “axial direction X”).

Further, in FIG. 1, the multi-cylinder engine 1 is illustrated in a vertical cross section along the axial direction X of the crankshaft 10, and the detailed illustration of the engine block 20 and the piston 2 is omitted in order to clarify the illustration. ing.
Further, in order to clarify the illustration, the oil groove portion 31a of the metal bearing 30 is omitted in FIGS. 5A and 6A. In addition, in FIG. 2, the branch oil passage 24b and the supply hole 30a extending in the direction intersecting the vertical direction are shown in the shape extending in the vertical direction in FIGS. 5 and 6 in order to clarify the illustration. There is.

First, the multi-cylinder engine 1 in the present embodiment is a 4-cylinder engine as shown in FIG. As shown in FIG. 1, the multi-cylinder engine 1 is rotatably connected to a crankshaft 10, an engine block 20, five metal bearings 30 that rotatably support the crankshaft 10, and a crankshaft 10. It is equipped with four connecting rods 40.

The crankshaft 10 is, for example, a rotary shaft body in which one end in the axial direction X is connected to a crank pulley (not shown) and the other end is connected to a transmission (not shown). As shown in FIG. 1, the crankshaft 10 is assumed to rotate in the clockwise rotation direction R1 when viewed from one end side (left side in FIG. 1) of the axial direction X.

As shown in FIG. 1, the crankshaft 10 includes a main journal 11 rotatably supported by the engine block 20, four pin journals 12 rotatably supporting the connecting rod 40, and four sets connecting them. It is integrally formed with the crank arm 13.

As shown in FIGS. 1 and 2, the main journal 11 has a substantially cylindrical shape extending in the axial direction X, and is composed of five rotating shaft bodies coaxially arranged at predetermined intervals in the axial direction X. .. The outer peripheral surface of the main journal 11 faces the metal bearing 30, which will be described later, in the radial direction via the lubricating film V (see FIG. 5), and is formed as a lipophilic sliding surface.

Specifically, as shown in FIG. 1, the main journal 11 has the first main journal 111, the second main journal 112, and the third main journal 113 in order from one end side (left side in FIG. 1) in the axial direction X. It is composed of five rotating shafts, a fourth main journal 114 and a fifth main journal 115.
Of these, the second main journal 112, the third main journal 113, and the fourth main journal 114 are located between the cylinders (not shown).

Further, as shown in FIGS. 1 and 2, the inside of the second main journal 112 and the inside of the fourth main journal 114 extend in the radial direction through the radial center and in the gap with the metal bearing 30. A through hole for communication is formed as an opening. The through hole is formed as a discharge path 11a for discharging the lubricating oil interposed in the gap with the metal bearing 30.

Further, as shown in FIGS. 1 and 3, the four pin journals 12 are substantially columnar rotating shafts extending in the axial direction X between the five rotating shafts constituting the main journal 11. It is arranged in a state of being offset radially outward with respect to the main journal 11.

The outer peripheral surface of the pin journal 12 is formed on a sliding surface facing the connecting rod 40, which will be described later, in the radial direction via a lubricating film W (see FIG. 7).
When the main journal 11 rotates in the rotation direction R1, the four pin journals 12 are clockwise when viewed from one end side (left side in FIG. 1) in the axial direction X with the main journal 11 as the center of rotation. It rotates in the rotation direction R1.

As shown in FIGS. 1 and 3, a through hole is formed inside the four pin journals 12 so as to extend in the radial direction through the radial center and communicate with the gap between the connecting rod 40 and the connecting rod 40. There is. This through hole is formed as a supply path 12a for supplying lubricating oil to the gap between the connecting rod 40 and the connecting rod 40.

Further, on the outer peripheral surface of the pin journal 12, an oil-repellent coating 12b (see FIG. 7B) having an oil-repellent property is formed on the entire peripheral surface excluding the supply path 12a. The oil-repellent coating 12b is composed of an oil-repellent fluororesin coating, more preferably a crosslinked fluororesin coating having oil repellency and high wear resistance.
Here, "having oil repellency" means that the oil repellency is higher than the base material surface (outer peripheral surface of the pin journal 12) on which the oil repellent coating 12b is formed.

Of the four pin journals 12, the pin journal 12 located between the first main journal 111 and the second main journal 112 is referred to as the first pin journal 121, and the second main journal 112 and the third main journal 113 are used. The pin journal 12 located between and is referred to as a second pin journal 122.

Further, the pin journal 12 located between the third main journal 113 and the fourth main journal 114 is referred to as the third pin journal 123, and the pin journal located between the fourth main journal 114 and the fifth main journal 115. Let 12 be the 4th pin journal 124.

Further, in the four sets of crank arms 13, as shown in FIG. 1, four pairs of crank arms 13 connecting one pin journal 12 to the main journal 11 are arranged at predetermined intervals in the axial direction X. It is configured.
Specifically, as shown in FIG. 1, the four sets of crank arms 13 include a pair of first crank arms 131, a pair of second crank arms 132, a pair of third crank arms 133, and a pair of fourth cranks. It is composed of an arm 134.

As shown in FIG. 1, the pair of first crank arms 131 are formed in a substantially flat plate shape extending radially outward from the first main journal 111 and the second main journal 112, respectively. The pair of first crank arms 131 support both ends of the first pin journal 121 in the axial direction X in a state in which relative rotation is not possible.

As shown in FIG. 1, the pair of second crank arms 132 are formed in a substantially flat plate shape extending radially outward from the second main journal 112 and the third main journal 113, respectively. The pair of second crank arms 132 support both ends of the second pin journal 122 in the axial direction X in a state in which relative rotation is not possible.

As shown in FIG. 1, the pair of third crank arms 133 are formed in a substantially flat plate shape extending outward in the radial direction from the third main journal 113 and the fourth main journal 114, respectively. The pair of third crank arms 133 support both ends of the third pin journal 123 in the axial direction X in a state in which relative rotation is not possible.

As shown in FIG. 1, the pair of fourth crank arms 134 are formed in a substantially flat plate shape extending radially outward from the fourth main journal 114 and the fifth main journal 115, respectively. The pair of fourth crank arms 134 support both ends of the fourth pin journal 124 in the axial direction X in a state in which relative rotation is not possible.

As shown in FIG. 1, four connecting oil passages 13a for connecting the discharge passage 11a of the main journal 11 and the supply passage 12a of the pin journal 12 are formed inside the four sets of crank arms 13. ing.
More specifically, as shown in FIG. 1, the four connecting oil passages 13a have a first crank arm 131 and a second crank arm 132 adjacent to the second main journal 112, and a second crank arm 132 adjacent to the fourth main journal 114. It is formed on the 3 crank arm 133 and the 4th crank arm 134.

Further, as shown in FIG. 1, the engine block 20 is a portion having a portion for accommodating and supporting the crankshaft 10 and four cylinders (not shown) accommodating the piston 2 connected to the connecting rod 40.
As shown in FIG. 1, the engine block 20 includes a support portion 21 that supports the main journal 11 of the crankshaft 10.

As shown in FIG. 2, the support portion 21 is composed of a saddle portion 22 integrally formed with a block body provided with a cylinder or the like and a separate body from the saddle portion 22, and is a cap fastened and fixed to the saddle portion 22. It is composed of a part 23.
As shown in FIG. 2, the saddle portion 22 and the cap portion 23 have a substantially circular bearing hole extending in the axial direction X with an inner diameter substantially the same as the outer diameter of the metal bearing 30 described later in the fastened state. It constitutes 21a.

Further, as shown in FIGS. 2 and 4, the engine block 20 is formed with a block oil passage 24 for supplying lubricating oil to the bearing hole 21a, and an oil pump 25 for pumping the lubricating oil to the block oil passage 24. Is provided.

More specifically, as shown in FIG. 4, the block oil passage 24 has a main oil passage 24a extending in the axial direction X from one end connected to the oil pump 25 and a saddle portion 22 branching from the main oil passage 24a. It is composed of four branch oil passages 24b extending to the bearing holes 21a.

As shown in FIG. 2, the branch oil passage 24b has a tip communicating with the supply hole 30a of the metal bearing 30, which will be described later.
Further, as shown in FIGS. 1 and 2, the metal bearing 30 is a slide bearing that supports the main journal 11 of the crankshaft 10 in the radial direction. As shown in FIGS. 1, 2, and 4, the metal bearing 30 is substantially opposed to the outer peripheral surface (sliding surface) of the main journal 11 in the radial direction and has an inner peripheral surface forming the sliding surface. It is formed in an annular shape.

As shown in FIGS. 5A and 6A, the metal bearing 30 has substantially the same outer diameter as the bearing hole 21a of the engine block 20 and the outer diameter of the main journal 11 in the cross section along the radial direction. It is formed in a substantially annular shape having an inner diameter slightly larger than the diameter.
Specifically, as shown in FIGS. 2 and 4, the metal bearing 30 is configured by assembling a first metal bearing 31 and a second metal bearing 32, which are substantially semicircular when viewed from the axial direction X, in the radial direction. Has been done.

As shown in FIG. 2, when the metal bearing 30 is mounted in the bearing hole 21a of the engine block 20, the outer peripheral surface of the first metal bearing 31 comes into contact with the saddle portion 22, and the outer peripheral surface of the second metal bearing 32 comes into contact with the saddle portion 22. Is arranged so as to come into contact with the cap portion 23.

Further, as shown in FIGS. 2 and 4, an oil groove portion 31a is formed on the inner peripheral surface of the first metal bearing 31 so that the substantially center of the axial direction X is recessed outward in the radial direction. As shown in FIG. 2, the oil groove portion 31a is formed with a supply hole 30a communicating with the branch oil passage 24b of the engine block 20. That is, the supply hole 30a of the metal bearing 30 is a block oil passage 24 and constitutes a supply passage for supplying lubricating oil to the gap between the main journal 11 and the metal bearing 30.

In addition, as shown in FIGS. 5 (b) and 6 (b), an oil-repellent coating 30b having oil repellency is formed on the entire peripheral surface of the metal bearing 30 including the oil groove portion 31a. ing. The oil-repellent coating 30b is composed of an oil-repellent fluororesin coating, more preferably a crosslinked fluororesin coating having oil repellency and high wear resistance.
Here, "having oil repellency" means that the oil repellency is higher than the base material surface (inner peripheral surface of the metal bearing 30) on which the oil repellent coating 30b is formed.

With the above-described configuration, the multi-cylinder engine 1 has a first oil supply unit that supplies lubricating oil to the inner peripheral surface of the metal bearing 30, and a second oil supply unit that supplies lubricating oil to the outer peripheral surface of the pin journal 12. An oil supply unit 5 connected to the oil supply unit is configured.

Specifically, as shown in FIG. 2, the oil supply unit 5 is provided with the inner peripheral surface of the metal bearing 30, that is, the main journal 11 by means of the oil pump 25, the block oil passage 24, and the supply hole 30a of the metal bearing 30. It constitutes a first oil supply unit that supplies lubricating oil to the gap between the metal bearing 30 and the metal bearing 30.

Further, as shown in FIGS. 2 and 3, the oil supply unit 5 is provided with a pin journal by the first oil supply unit, the discharge passage 11a of the main journal 11, the connecting oil passage 13a, and the supply passage 12a of the pin journal 12. It constitutes a second oil supply unit that supplies lubricating oil to the outer peripheral surface of 12, that is, the gap between the pin journal 12 and the connecting rod 40.

Further, as shown in FIGS. 1 and 3, the connecting rod 40 is a connecting member that connects the pin journal 12 of the crankshaft 10 and the piston 2. As shown in FIG. 3, the connecting rod 40 is composed of a rod body 41 whose one end is connected to the piston 2 via a piston pin 3 and a cap portion 42 which is fastened and fixed to the rod body 41.

As shown in FIGS. 1 and 3, the rod body 41 and the cap portion 42 are configured to support the pin journal 12 in the radial direction and function as a slide bearing in the fastened state. ..

When the main journal 11 rotates in the rotation direction R1, the connecting rod 40 with respect to the pin journal 12 is pinned when viewed from one end side in the axial direction X (left side in FIG. 1) as shown in FIG. It rotates in the clockwise rotation direction R2 with the journal 12 as the center of rotation.

Specifically, as shown in FIGS. 3 and 7A, the rod body 41 and the cap portion 42 have a diameter slightly larger than the outer diameter of the pin journal 12 and a shaft in a state of being fastened to each other. It constitutes a substantially circular bearing hole 40a extending in the direction X.
The peripheral surface of the bearing hole 40a faces the outer peripheral surface of the pin journal 12 in the radial direction via the lubricating film W (see FIG. 7), and is formed as a lipophilic sliding surface.

Further, as shown in FIGS. 1 and 7A, an opening of a discharge path 41a for discharging the lubricating oil in the gap between the bearing hole 40a and the pin journal 12 is formed on the peripheral surface of the bearing hole 40a.
The discharge path 41a extends the inside of the rod body 41 toward the other end side and communicates with the pin hole 41b through which the piston pin 3 is inserted. In other words, the discharge path 41a is formed as a supply path for supplying lubricating oil to the pin hole 41b.

Next, in the above-described configuration, the lubricating film interposed between the main journal 11 and the metal bearing 30 and the gap between the pin journal 12 and the bearing hole 40a of the connecting rod 40 will be described with reference to FIGS. 5 to 7. .. The lubricating film is formed as the crankshaft 10 rotates.

As shown in FIGS. 5 (b) and 6 (b), the lubricating film V formed in the gap between the main journal 11 and the metal bearing 30 is composed of two layers adjacent to each other in the radial direction. More specifically, as shown in FIGS. 5 (b) and 6 (b), the lubricating film V includes an oil layer Vo in contact with the outer peripheral surface of the main journal 11 and an inner peripheral surface (oil repellent film 30b) of the metal bearing 30. ) Is in contact with the air layer Va.

The oil layer Vo is composed of the lubricating oil S supplied through the supply hole 30a of the metal bearing 30. On the other hand, the air layer Va is composed of air separated from the lubricating oil S.
Such a lubricating film V is formed by the oil-repellent coating film 30b of the metal bearing 30 and the shear stress acting on the lubricating oil S.

More specifically, the lubricating oil S flowing out from the supply hole 30a of the metal bearing 30 flows from the supply hole 30a so as to adhere to the inner peripheral surface of the metal bearing 30. However, due to the oil-repellent coating 30b continuous with the supply hole 30a and the shear stress acting on the lubricating oil S, the lubricating oil S cannot continue to adhere to the inner peripheral surface of the metal bearing 30. Therefore, the lubricating oil S moves to the main journal 11 side so as to be repelled by the oil-repellent coating 30b as the crankshaft 10 rotates.

At this time, since the lubricating oil S contains a small amount of air, the lubricating oil S moves to the main journal 11 side so as to leave the contained air on the metal bearing 30 side. Therefore, an air layer (air layer Va) separated from the lubricating oil S is formed in the gap between the lubricating oil S and the oil-repellent coating 30b of the metal bearing 30.
In this way, a lubricating film V composed of an oil layer Vo in contact with the main journal 11 and an air layer Va in contact with the metal bearing 30 is formed in the gap between the main journal 11 and the metal bearing 30.

Further, as shown in FIG. 7B, the lubricating film W formed in the gap between the pin journal 12 and the bearing hole 40a of the connecting rod 40 is composed of two layers adjacent to each other in the radial direction. More specifically, as shown in FIG. 7B, the lubricating film W has an air layer Wa in contact with the outer peripheral surface (oil repellent film 12b) of the pin journal 12 and an oil layer in contact with the peripheral surface of the bearing hole 40a of the connecting rod 40. It is composed of Wo.

The oil layer Wo is composed of the lubricating oil S supplied through the supply path 12a of the pin journal 12. On the other hand, the air layer Wa is composed of air separated from the lubricating oil S.
Such a lubricating film W is formed by the oil-repellent coating film 12b of the pin journal 12 and the shear stress acting on the lubricating oil S.

More specifically, the lubricating oil S flowing out from the supply path 12a of the pin journal 12 flows from the supply path 12a so as to adhere to the outer peripheral surface of the pin journal 12. However, due to the oil-repellent coating 12b continuous with the supply path 12a and the shear stress acting on the lubricating oil S, the lubricating oil S cannot continue to adhere to the outer peripheral surface of the pin journal 12. Therefore, the lubricating oil S moves toward the connecting rod 40 so as to be repelled by the oil-repellent coating 12b as the crankshaft 10 rotates.

At this time, since the lubricating oil S contains a small amount of air, the lubricating oil S moves to the connecting rod 40 side so as to leave the contained air on the pin journal 12 side. Therefore, an air layer (air layer Wa) separated from the lubricating oil S is formed in the gap between the lubricating oil S and the oil-repellent coating 12b of the pin journal 12.
In this way, in the gap between the pin journal 12 and the bearing hole 40a of the connecting rod 40, a lubricating film W composed of an air layer Wa in contact with the pin journal 12 and an oil layer Wo in contact with the bearing hole 40a of the connecting rod 40 is formed. It is formed.

Subsequently, the flow of the lubricating oil S in the state where the above-mentioned lubricating films V and W are formed will be described in detail with reference to FIGS. 5 to 7.
First, in the gap between the main journal 11 on which the lubricating film V is formed and the metal bearing 30, the lubricating oil S passes through the supply hole 30a as shown by the arrow L1 in FIGS. 5 (b) and 6 (b). Then, it flows into the air layer Va.

At this time, the lubricating oil S that has flowed into the air layer Va cannot adhere to the oil-repellent coating 30b. Therefore, the lubricating oil S that has flowed into the air layer Va joins the oil layer Vo while separating the contained air, as shown by the arrows L2 in FIGS. 5 (b) and 6 (b), and joins the main journal. It flows along the outer peripheral surface of 11.

Then, as shown by the arrow L3 in FIG. 5B, the lubricating oil S flowing through the oil layer Vo is discharged from the gap between the main journal 11 and the metal bearing 30 via the discharge path 11a.
In the first main journal 111, the third main journal 113, and the fifth main journal 115 in which the discharge path is not formed, the lubricating oil S flows in the axial direction X through the gap between the main journal 11 and the metal bearing 30. Is discharged to the outside.

Further, in the gap between the pin journal 12 on which the lubricating film W is formed and the bearing hole 40a of the connecting rod 40, as shown by the arrow L4 in FIG. 7B, the lubricating oil S passes through the supply path 12a and air. It flows into the layer Wa. At this time, the lubricating oil S flowing into the air layer Wa cannot adhere to the oil-repellent coating 12b.

Therefore, as shown by the arrow L5 in FIG. 7B, the lubricating oil S flowing into the air layer Wa joins the oil layer Wo while separating the contained air, and is along the peripheral surface of the bearing hole 40a. Flows.
Then, as shown by the arrow L6 in FIG. 7B, the lubricating oil S flowing through the oil layer Wo is discharged from the gap between the pin journal 12 and the bearing hole 40a of the connecting rod 40 via the discharge path 41a. It is supplied to the gap between the pin hole 41b of the connecting rod 40 and the crank pin 3.

As described above, in the gap between the main journal 11 and the metal bearing 30 and the gap between the pin journal 12 and the bearing hole 40a of the connecting rod 40, the lubricating oil S is radiated in the radial direction until the rotation of the crankshaft 10 is stopped. By continuously flowing toward the air layer Va, the lubricating film V having the air layer Va and the lubricating film W having the air layer Wa are continuously formed.

As described above, the oil-lubricated bearing structure includes a substantially columnar main journal 11 and a metal bearing 30 that supports the main journal 11 in the radial direction of the main journal 11. This oil-lubricated bearing structure includes an oil supply unit 5 that supplies lubricating oil to a gap between the main journal 11 and the metal bearing 30. The entire surface of the sliding surface of the metal bearing 30 is formed of an oil-repellent coating 30b having oil-repellent properties.

As a result, the oil-lubricated bearing structure suppresses the sliding resistance between the main journal 11 and the metal bearing 30 even when the lubricating film V having a film thickness capable of preventing the occurrence of oil film breakage is interposed. Can be done.

Specifically, the oil-repellent coating 30b can separate only the oil while allowing contact with air contained in the oil. Therefore, when lubricating oil containing air is supplied to the gap between the main journal 11 and the metal bearing 30 due to the relative rotation between the main journal 11 and the metal bearing 30, the oil-lubricated bearing structure becomes lubricating oil. The lubricating oil can be separated from the inner peripheral surface of the metal bearing 30 by leaving the air contained in the metal bearing 30 on the inner peripheral surface side of the metal bearing 30.

That is, the oil-lubricated bearing structure can separate the air contained in the lubricating oil as the main journal 11 and the metal bearing 30 rotate relative to each other. Therefore, the oil-lubricated bearing structure includes a lubricating film V composed of a thin film air layer Va in contact with the inner peripheral surface of the metal bearing 30 which is an oil-repellent film 30b and an oil layer Vo in contact with the outer peripheral surface of the main journal 11. , It can be formed in the gap between the main journal 11 and the metal bearing 30 without separately providing an air supply unit.

As a result, the oil-lubricated bearing structure can form the lubricating film V in which the film thickness of the oil layer Vo is suppressed as compared with the case where the lubricating film is formed only with the lubricating oil, so that the shear stress of the oil layer Vo can be suppressed.

Further, for example, when the radial load is relatively small, the oil-lubricated bearing structure supports the main journal 11 in a floating state by the oil layer Vo and the air layer Va. In this case, the oil-lubricated bearing structure can suppress the sliding resistance between the main journal 11 and the metal bearing 30 by the air layer Va having a lower viscous resistance than the lubricating oil.

Furthermore, even when the radial load is relatively large and it is difficult to maintain the air layer Va, the oil-lubricated bearing structure provides an oil-repellent coating on the frictional resistance between the oil layer Vo and the inner peripheral surface of the metal bearing 30. Since it can be reduced by 30b, the sliding resistance between the main journal 11 and the metal bearing 30 can be suppressed.

Therefore, the oil-lubricated bearing structure can suppress the sliding resistance between the main journal 11 and the metal bearing 30 even when the lubricating film V having a film thickness capable of preventing the occurrence of oil film breakage is interposed. it can.

Further, the oil-lubricated bearing structure includes a substantially columnar pin journal 12 and a bearing hole 40a of a connecting rod 40 that supports the pin journal 12 in the radial direction of the pin journal 12. This oil-lubricated bearing structure includes an oil supply unit 5 that supplies lubricating oil to the gap between the pin journal 12 and the bearing hole 40a of the connecting rod 40. The entire surface of the sliding surface of the pin journal 12 is formed of an oil-repellent coating 12b having oil-repellent properties.

As a result, the oil-lubricated bearing structure provides sliding resistance between the pin journal 12 and the bearing hole 40a of the connecting rod 40 even when a lubricating film W having a film thickness that can prevent the occurrence of oil film breakage is interposed. It can be suppressed.

Specifically, the oil-repellent coating 12b can separate only the oil while allowing contact with air contained in the oil. Therefore, when lubricating oil containing air is supplied to the gap between the pin journal 12 and the bearing hole 40a of the connecting rod 40 as the pin journal 12 and the bearing hole 40a of the connecting rod 40 rotate relative to each other, oil lubrication is performed. The bearing structure can separate the lubricating oil from the outer peripheral surface of the pin journal 12 by leaving the air contained in the lubricating oil on the outer peripheral surface side of the pin journal 12.

That is, the oil-lubricated bearing structure can separate the air contained in the lubricating oil as the pin journal 12 and the bearing hole 40a of the connecting rod 40 rotate relative to each other. Therefore, the oil-lubricated bearing structure includes a lubricating film W composed of an air layer Wa of a thin film in contact with the outer peripheral surface of the pin journal 12 which is an oil-repellent coating 12b and an oil layer Wo in contact with the peripheral surface of the bearing hole 40a. It can be formed in the gap between the pin journal 12 and the bearing hole 40a of the connecting rod 40 without separately providing an air supply unit.

As a result, the oil-lubricated bearing structure can form the lubricating film W in which the film thickness of the oil layer Wo is suppressed as compared with the case where the lubricating film is formed only with the lubricating oil, so that the shear stress of the oil layer Wo can be suppressed.

Further, for example, when the radial load is relatively small, the oil-lubricated bearing structure supports the pin journal 12 in a floating state by the oil layer Wo and the air layer Wa. In this case, in the oil-lubricated bearing structure, the sliding resistance between the pin journal 12 and the bearing hole 40a of the connecting rod 40 can be suppressed by the air layer Wa having a lower viscous resistance than the lubricating oil.

Furthermore, even when the radial load is relatively large and it is difficult to maintain the air layer Wa, the oil-lubricated bearing structure provides an oil-repellent coating 12b for frictional resistance between the oil layer Wo and the outer peripheral surface of the pin journal 12. Therefore, the sliding resistance between the pin journal 12 and the bearing hole 40a of the connecting rod 40 can be suppressed.

Therefore, the oil-lubricated bearing structure suppresses the sliding resistance between the pin journal 12 and the bearing hole 40a of the connecting rod 40 even when the lubricating film W having a film thickness capable of preventing the occurrence of oil film breakage is interposed. can do.

Further, the oil-lubricated bearing structure includes a discharge path 11a for discharging lubricating oil interposed between the main journal 11 and the metal bearing 30. The oil supply unit 5 is formed with an opening on the inner peripheral surface of the metal bearing 30 which is the oil-repellent coating 30b. On the other hand, the discharge path 11a is formed with an opening on the outer peripheral surface of the main journal 11.

According to this configuration, the oil-lubricated bearing structure can reliably flow the lubricating oil from the oil supply unit 5 (first oil supply unit) to the discharge passage 11a.
Specifically, the oil layer Vo in contact with the outer peripheral surface of the main journal 11 is hindered by the oil repellent coating 30b and the air layer Va even when pressed toward the inner peripheral surface of the metal bearing 30. , Cannot contact the inner peripheral surface of the metal bearing 30.

Therefore, for example, when the oil supply section is formed with an opening on the outer peripheral surface of the main journal 11 and the discharge path is formed on the inner peripheral surface of the metal bearing 30 having the oil-repellent coating 30b, the oil is supplied from the oil supply section. Lubricating oil cannot flow into the discharge path beyond the air layer Va.

On the other hand, the oil-lubricated bearing structure is supplied to the air layer Va by forming an opening in the inner peripheral surface of the metal bearing 30 having the oil-repellent coating 30b in the oil supply unit 5 (first oil supply unit). The lubricating oil can be flowed to the oil layer Vo while separating the contained air by the relative rotation of the main journal 11 and the metal bearing 30 and the cooperation with the oil-repellent coating 30b.

Further, since the discharge path 11a having an opening formed on the outer peripheral surface of the main journal 11 is in contact with the oil layer Vo, the oil-lubricated bearing structure can smoothly discharge the lubricating oil of the oil layer Vo to the discharge path 11a.
Therefore, in the oil-lubricated bearing structure, the lubricating oil can be reliably flowed from the oil supply unit 5 (first oil supply unit) to the discharge path 11a, and stable lubrication is performed between the main journal 11 and the metal bearing 30. A film V can be formed.

Further, the oil-lubricated bearing structure includes a discharge path 41a for discharging lubricating oil interposed between the pin journal 12 and the bearing hole 40a of the connecting rod 40. The oil supply unit 5 is formed with an opening on the outer peripheral surface of the pin journal 12 which is the oil-repellent coating 12b. On the other hand, the discharge path 41a is formed with an opening on the peripheral surface of the bearing hole 40a.

According to this configuration, the oil-lubricated bearing structure can reliably flow the lubricating oil from the oil supply unit 5 (second oil supply unit) to the discharge path 41a.
Specifically, the oil layer Wo in contact with the peripheral surface of the bearing hole 40a is hindered by the oil repellent coating 12b and the air layer Wa even when pressed toward the outer peripheral surface of the pin journal 12. It cannot touch the outer peripheral surface of the pin journal 12.

Therefore, for example, when the oil supply portion is formed with an opening on the peripheral surface of the bearing hole 40a and the discharge path is formed on the outer peripheral surface of the pin journal 12 having the oil-repellent coating 12b, the lubrication supplied from the oil supply portion is formed. Oil cannot flow into the discharge channel beyond the air layer Wa.

On the other hand, the oil-lubricated bearing structure was supplied to the air layer Wa by forming an opening on the outer peripheral surface of the pin journal 12 which is the oil-repellent coating 12b in the oil supply unit 5 (second oil supply unit). The lubricating oil can be flowed to the oil layer Wo while separating the contained air by the relative rotation of the bearing holes 40a of the pin journal 12 and the conrod 40 and the cooperation with the oil-repellent coating 12b.

Further, since the discharge path 41a having an opening formed in the peripheral surface of the bearing hole 40a is in contact with the oil layer Wo, the oil-lubricated bearing structure can smoothly discharge the lubricating oil of the oil layer Wo to the discharge path 41a.
Therefore, in the oil-lubricated bearing structure, the lubricating oil can be reliably flowed from the oil supply unit 5 (second oil supply unit) to the discharge path 41a, and between the pin journal 12 and the bearing hole 40a of the conrod 40. A stable lubricating film W can be formed.

Further, since the oil-repellent coatings 30b and 12b are composed of the fluororesin coating, the oil-lubricated bearing structure can form the oil-repellent coatings 30b and 12b exhibiting higher oil repellency. Therefore, in the oil-lubricated bearing structure, the lubricating film V composed of the air layer Va and the oil layer Vo and the lubricating film W composed of the air layer Wa and the oil layer Wo can be more reliably formed.

Therefore, the oil-lubricated bearing structure can surely suppress the sliding resistance between the main journal 11 and the metal bearing 30 and the sliding resistance between the pin journal 12 and the bearing hole 40a of the connecting rod 40.

Further, since the fluororesin coating is formed of the crosslinked fluororesin, the oil-lubricated bearing structure can further improve the wear resistance of the oil-repellent coatings 30b and 12b. Therefore, in the oil-lubricated bearing structure, the oil-repellent coatings 30b and 12b can be secured for a long period of time.
Therefore, the oil-lubricated bearing structure can suppress the sliding resistance between the main journal 11 and the metal bearing 30 and the sliding resistance between the pin journal 12 and the bearing hole 40a of the connecting rod 40 for a long period of time.

Further, since the rotating shaft is the crankshaft 10 of the multi-cylinder engine 1, the oil-lubricated bearing structure has a lubricating film V having an air layer Va even if the crankshaft 10 has a large fluctuation range of the radial load. The sliding resistance can be stably suppressed by the cooperation with the oil-repellent film 30b and the cooperation between the lubricating film W having the air layer Wa and the oil-repellent film 12b.

In the correspondence between the configuration of the present invention and the above-described embodiment,
The rotating shaft body of the present invention corresponds to the main journal 11 and the pin journal 12 of the embodiment.
Similarly below
The plain bearing corresponds to the bearing hole 40a of the metal bearing 30 and the connecting rod 40.
One sliding surface corresponds to the inner peripheral surface of the metal bearing 30 and the outer peripheral surface of the pin journal 12.
The oil-repellent surface corresponds to the oil-repellent coating 30b and the oil-repellent coating 12b.
The oil discharge section corresponds to the discharge path 11a and the discharge path 41a.
The other sliding surface corresponds to the outer peripheral surface of the main journal 11 and the peripheral surface of the bearing hole 40a.
The engine corresponds to the multi-cylinder engine 1,
The present invention is not limited to the configuration of the above-described embodiment, and many embodiments can be obtained.

For example, in the above-described embodiment, the oil-lubricated bearing structure has been described using the crankshaft 10 of the multi-cylinder engine 1, but the present invention is not limited to this, and oil that supports an appropriate rotating shaft body with a lubricating film and a slide bearing. It may be applied to a lubricated bearing structure. For example, it may be applied to an oil-lubricated bearing structure having a camshaft, a piston pin, an oil pump shaft of a multi-cylinder engine, a turbine shaft of a supercharger, or the like as a rotating shaft.

Further, the present invention is not limited to the oil-lubricated bearing structure in a multi-cylinder engine, and may be applied to an appropriate device in which the rotating shaft body is supported by a lubricating film and a slide bearing. For example, it may be applied to an internal combustion engine or a transmission such as a vehicle, an aircraft, or a ship.

Further, it may be applied to a bearing structure that supports a rotating shaft body in a machine tool, an assembly machine, a test facility, or the like. The rotating shaft and the slide bearing may be relatively rotatable. For example, the slide bearing is non-rotating and the rotating shaft is relatively rotating, or the rotating shaft is non-rotating and the sliding bearing is rotating. It may be.

Further, the oil supply unit 5 to which the oil pump 25 is connected to one end supplies lubricating oil to the gap between the main journal 11 and the metal bearing 30 and the gap between the pin journal 12 and the bearing hole 40a of the conrod 40. However, if the lubricating oil can be supplied, the present invention is not limited to this.
For example, it may be an oil supply unit that supplies lubricating oil from the axial direction X to the gap between the main journal 11 and the metal bearing 30 or / and the gap between the pin journal 12 and the bearing hole 40a of the connecting rod 40. ..

Further, the lubricating oil interposed in the gap between the pin journal 12 and the bearing hole 40a of the connecting rod 40 is discharged through the discharge path 41a provided in the connecting rod 40, but the lubricating oil is not limited to this, and the lubricating oil is discharged in the axial direction X. It may be configured to be discharged. More specifically, the connecting rod may not be provided with a discharge path, and the lubricating oil may be discharged in the axial direction X through the gap between the pin journal 12 and the bearing hole 40a of the connecting rod 40.

Further, the main journal 11 is supported by the metal bearing 30, but the present invention is not limited to this, and any slide bearing may be a bearing formed of an appropriate material.
Further, the bearing hole 40a of the connecting rod 40 is configured to function as a slide bearing, but the present invention is not limited to this, and a metal bearing is interposed between the pin journal 12 and the bearing hole 40a as in the main journal 11. You may. In this case, the metal bearing is formed with an opening that communicates with the discharge path 11a of the connecting rod 40.

Further, the oil-repellent coatings 30b and 12b made of a fluororesin or a crosslinked fluororesin coating are used, but the present invention is not limited to this, and any configuration can be used as long as an oil-repellent surface having high oil repellency can be formed. There may be. For example, it may be an oil-repellent film made of a film made of a material different from that of a fluororesin, or an oil-repellent surface whose oil-repellent property is enhanced by uneven processing applied to the peripheral surface.

1 ... Multi-cylinder engine 5 ... Oil supply unit 10 ... Crankshaft 11 ... Main journal 11a ... Discharge passage 12 ... Pin journal 12b ... Oil repellent coating 30 ... Metal bearing 30b ... Oil repellent coating 40a ... Bearing hole 41a ... Discharge passage S ... Lubricant

Claims (5)

Approximately columnar rotating shaft and
An oil-lubricated bearing structure including a slide bearing that supports the rotating shaft body in the radial direction of the rotating shaft body.
An oil supply unit for supplying lubricating oil to the gap between the rotating shaft body and the slide bearing is provided.
Of the sliding surface of the rotating shaft body or the sliding surface of the slide bearing, one of the sliding surfaces is
An oil-lubricated bearing structure whose entire surface is formed of an oil-repellent surface having oil-repellent properties. An oil discharge portion for discharging the lubricating oil interposed between the rotating shaft body and the slide bearing is provided.
The oil supply unit
An opening is formed on one of the sliding surfaces, which is the oil-repellent surface.
The oil discharge part is
The oil-lubricated bearing structure according to claim 1, wherein an opening is formed in the other sliding surface. The oil-lubricated bearing structure according to claim 1 or 2, wherein the oil-repellent surface is formed of a fluororesin film. The oil-lubricated bearing structure according to claim 3, wherein the fluororesin coating is formed of a crosslinked fluororesin. The oil-lubricated bearing structure according to any one of claims 1 to 4, wherein the rotating shaft body is a crankshaft of an engine.

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