阅读说明：本技术 具有油孔的连杆部件 (Connecting rod component with oil hole ) 是由 杉本刚 浜田孝浩 于 2018-01-31 设计创作，主要内容包括：本发明提供一种连杆部件(150),其安装于内燃机E的曲轴(106)且具有从外侧连通到所述曲轴(106)侧的油孔(150E),其中,该连杆部件(150)中,油孔(150E)在曲轴(106)侧的开口部周缘具有倾斜面(150F),油孔(150E)以外的表面的碳浓度为0.5wt％以上,倾斜面(150F)的碳浓度为0.7wt％以上且0.9wt％以下的范围,抑制制造成本,并且,提高容易产生应力集中的油孔部分的耐性,实现破损的防止。(The invention provides a connecting rod part (150) which is mounted on a crankshaft (106) of an internal combustion engine E and is provided with an oil hole (150E) communicated with the crankshaft (106) side from the outside, wherein in the connecting rod part (150), the oil hole (150E) is provided with an inclined surface (150F) at the opening periphery of the crankshaft (106), the carbon concentration of the surface except the oil hole (150E) is more than 0.5 wt%, the carbon concentration of the inclined surface (150F) is more than 0.7 wt% and less than 0.9 wt%, the manufacturing cost is inhibited, the resistance of the oil hole part which is easy to generate stress concentration is improved, and the damage is prevented.)

1. A connecting rod member having an oil hole, which is attached to a crankshaft of an internal combustion engine and has an oil hole communicating from the outside to the crankshaft side,

the oil hole has an inclined surface at the periphery of the opening part on the crankshaft side,

the carbon concentration of the surface other than the oil hole is 0.5 wt% or more,

the carbon concentration of the inclined surface is in the range of 0.7 wt% to 0.9 wt%.

2. The connecting rod part having the oil hole as set forth in claim 1,

the inclined surface has an arithmetic surface roughness Ra of 1.7 [ mu ] m or less and a maximum height Ry of 9.8 [ mu ] m or less.

3. The connecting rod part having the oil hole according to claim 1 or 2,

the Rockwell hardness of the inclined surface is more than 58 HRC.

4. A connecting rod part having an oil hole according to any one of claims 1 to 3,

the thickness of the grain boundary oxide layer on the surface of the inclined surface is 5 [ mu ] m or less.

5. A method of manufacturing a connecting rod member, characterized in that,

in manufacturing the connecting rod part with an oil hole according to any one of claims 1 to 4,

comprises a step of subjecting the connecting rod member to a carburizing treatment,

the carburizing treatment is vacuum carburizing treatment.

Technical Field

The present invention relates to a connecting rod member attached to a crankshaft of an internal combustion engine, and more particularly to a connecting rod member having an oil hole communicating from the outside to the crankshaft side.

Background

The link member is, for example, an intermediate link having a double action link mechanism for a variable compression ratio engine. The intermediate link is formed of a pair of link members divided at an insertion portion of the crankpin so as to be attached to the crankpin of the crankshaft. Each link member has an oil hole communicating from the outside to the crank shaft side, i.e., the crank pin side. The intermediate link is attached to the crankpin by connecting link members joined to each other with the crankpin interposed therebetween with a bolt. Further, other links constituting the double action link mechanism are connected to the respective link members.

Since the intermediate link repeatedly receives bending input during operation of the engine, a material and a reinforcing process having high bending fatigue strength are required in manufacturing. A connecting rod that ensures high hardness and high toughness includes a member described in patent document 1. Patent document 1 describes a steel material to which Si, Al, Cr, Mo, V, W, Ni and Co are appropriately added, the steel material being a high-hardness high-toughness steel having a hardness of HRC50 or more by high-temperature tempering at 600 ℃. The carburizing and quenching treatment is a technique for improving the bending fatigue resistance of a steel member by immersing carbon in the surface of the member and rapidly cooling the carbon to form a dense martensite structure on the surface.

Patent document 1 Japanese patent laid-open publication No. 2003-328078

However, when the link member of the intermediate link receives a bending input, particularly bending stress is concentrated on a portion where the oil hole is provided, and therefore, the portion may become a starting point of breakage. However, in the normal carburizing and quenching treatment, the oil hole portion and the other portions have the same heat treatment quality, and therefore, it is difficult to respond to a large bending stress in the oil hole portion. As a countermeasure, the method described in patent document 1 may be adopted, but the technique described in patent document 1 has a problem in that the tempering temperature is high and the amount of additive elements of the material is large, which increases the production cost.

Disclosure of Invention

The present invention has been made in view of the above-described circumstances, and an object of the present invention is to provide a connecting rod member with an oil hole, which is attached to a crankshaft of an internal combustion engine, and which has an oil hole, and which can suppress manufacturing costs, and can improve resistance of an oil hole portion where stress concentration is likely to occur, thereby preventing breakage.

A connecting rod member having an oil hole is attached to a crankshaft of an internal combustion engine and has an oil hole communicating from the outside to the crankshaft side. The connecting rod member is characterized in that the oil hole has an inclined surface at the periphery of the opening on the crankshaft side, the carbon concentration of the surface other than the oil hole is 0.5 wt% or more, and the carbon concentration of the inclined surface is in the range of 0.7 wt% or more and 0.9 wt% or less.

The connecting rod component with the oil hole is provided with an inclined surface at the periphery of an opening part of the oil hole on the crankshaft side, and the carbon concentration of the inclined surface is higher than that of other parts, so that the initial cracking strength is improved, and the breakage of the oil hole part which is easy to generate stress concentration is prevented.

In this case, the carbon concentration of the surface of the connecting rod member other than the oil hole is set to 0.5 wt% or more, and the lower limit of the carbon concentration of the inclined surface is set to 0.7 wt%, whereby the material durability is ensured. In addition, the upper limit of the carbon concentration of the inclined surface of the connecting rod member is set to 0.9 wt%, so that generation of cementite causing breakage is suppressed, and breakage of the cementite base point, which may not be considered in a normal case, is prevented. The connecting rod component does not need a large amount of added elements and high-temperature tempering.

Thus, the connecting rod member having the oil hole according to the present invention can suppress the manufacturing cost, and can improve the resistance of the oil hole portion where stress concentration is likely to occur, thereby preventing damage.

Drawings

Fig. 1 is a sectional view illustrating a variable compression ratio engine to which a link member can be applied in a first embodiment of the link member of the present invention;

fig. 2 is a side view illustrating an intermediate link as a link member in a disassembled state;

FIG. 3 is a perspective view of a link as a link component;

FIG. 4 is a perspective view of the oil hole portion of the connecting rod part;

fig. 5 is a sectional view of the oil hole portion of the connecting rod part.

Description of the marks

E: variable compression ratio engine (internal combustion engine)

150: connecting rod parts (connecting rod)

150E: oil hole

150F: inclined plane

106: crankshaft

Detailed Description

First embodiment

Fig. 1 is a sectional view illustrating a variable compression ratio engine to which a connecting rod member having an oil hole (hereinafter, simply referred to as "connecting rod member") of the present invention is applicable. In the variable compression ratio engine E shown in the figure, the upper end portion of an upper connecting rod 104 is connected to a piston 102 that reciprocates inside a cylinder 101 via a piston pin 103. The lower end of the upper link 104 is connected to one end of the intermediate link 105 via a first link pin P1 and a first bushing B1.

The intermediate link 105 has a crank pin 107 of the crankshaft 106 inserted through the center thereof, and the other end thereof is connected to the upper end of the lower link 108 via a second link pin P2 and a second bushing B2. The lower link 108 is connected to a control rod 109 at a lower end portion thereof, and is connected to an actuator (not shown) that reciprocates the control rod 109 in parallel.

The variable compression ratio engine E having the above-described configuration moves the control lever 109 to rotate the lower link 108 about the crank pin 107. Thus, the variable compression ratio engine E changes the length from the crank pin 107 to the piston pin 103, i.e., the connecting rod length L, changes the stroke of the piston 102, and changes the compression ratio.

Here, the intermediate link 105 is configured by a pair of link members 150 and 150 divided at an insertion portion of the crankpin 107 as shown in fig. 2 in order to be attached to the crankpin 107 of the crankshaft 106. The 2 link members 150 and 150 have the same configuration and have a rotationally symmetrical shape about the crank pin 107 on the side shown in fig. 2.

Further, the intermediate link 105 has a link member 150 rotatably coupled to the lower end portion of the upper link 104 via a first link pin P1 and a first bushing B1. The other link member 150 is coupled to the upper end portion of the lower link 108 via a second link pin P2 and a second bushing B2.

As shown in fig. 3, each link member 150 has a semicircular attachment portion 150A corresponding to a half turn of the crank pin 107 on the side of the joint surface Sa with the other side (lower side in fig. 3).

Each link member 150 has a bolt insertion hole 150B whose axis is perpendicular to the joint surface Sa on one side (left side in fig. 3) and a pair of ribs 150C, 150C on the other side, on the opposite side (upper side in fig. 3) to the joint surface Sa. Each rib 150C is provided with a mounting hole 150D for mounting the first link pin P1 and the bushing B1 (or the second link pin P2 and the bushing B2).

Each link member 150 has an oil hole 150E communicating from the outside to the crankshaft side. The oil hole 150E communicates with the mounting portion 150A of the crank pin 107 from a position between the bolt through hole 150B and the rib 150C on the outer side. The oil hole 150E continuously supplies the lubricating oil from the outside of the connecting rod member 150 to the crank pin 107 side.

The intermediate link 105 is brought into a state of sandwiching the crank pin 107, and the link members 150 and 150 are joined to each other and, as shown in fig. 2, coupled by a bolt BT screwed to the link member 150 on the other side through a link member 150. Thereby, the intermediate link 105 is attached to the crank pin 107.

The connecting rod part having the oil hole of the present invention is suitable for constituting the connecting rod part 150 of the intermediate connecting rod 150. The connecting rod member 150 as a connecting rod member is attached to the crankshaft 106 of the variable compression ratio engine (internal combustion engine) E, and has an oil hole 150E communicating with the crankshaft 106 side from the outside. Further, the connecting rod member 150 is directly attached to the crank pin 107, but it goes without saying that the crank pin 107 is a part of the crankshaft 106.

When the variable compression ratio engine E is operated, the intermediate connecting rod 105 performs an operation of rotating the crank pin 107 about the central axis of the crankshaft 106 in accordance with the reciprocating movement of the piston 102, and therefore, repeatedly receives a bending input. At this time, the link member 150 constituting the intermediate link 150 is likely to concentrate bending stress at a portion where the oil hole 150E is provided.

Therefore, as shown in fig. 4, the connecting rod member 150 has a chamfered inclined surface 150F at the periphery of the opening of the oil hole 150E on the crankshaft 106 side and the crank pin 107 side. The connecting rod member 150 has a carbon concentration of 0.5 wt% or more on the surface other than the oil hole 150E, and a carbon concentration of 0.7 wt% or more and 0.9 wt% or less on the inclined surface 150F.

In the production of the connecting rod member 150, it is not necessary to add a large amount of elements and to temper at high temperature as in the conventional case, and a desired carbon concentration and hardness can be controlled by the angle and area of the inclined surface 150F, the carburizing treatment, and the quenching.

The connecting rod member 150 has an inclined surface 150F formed on the periphery of the opening of the oil hole 105E on the crankshaft 106 side, and the carbon concentration of the inclined surface 150F is higher than that of the other portions, thereby increasing the initial crack strength and preventing the breakage of the portion of the oil hole where stress concentration is likely to occur.

That is, the material strength of the connecting rod member 150 is ensured by setting the carbon concentration of the surface other than the oil hole 150E to 0.5 wt% or more and setting the lower limit of the carbon concentration of the inclined surface 150F to 0.7 wt%. In the connecting rod member 150, the upper limit of the carbon concentration of the inclined surface 150F is set to 0.9 wt%, so that generation of cementite causing breakage is suppressed, and breakage of the cementite base point, which is not considered in a normal case, is prevented.

That is, in the connecting rod member 150, when it is considered that there is no inclined surface at the opening peripheral edge of the oil hole 150E and the opening peripheral edge is an angle, the opening surface and the inner surface of the oil hole 150E are carburized at the time of the carburizing treatment, and therefore, the carburization concentration of the angle becomes significantly high. As a result, cementite is likely to be generated in the structure around the opening of the oil hole 150E.

Therefore, in the above-described link member 150, the inclined surface 150F is provided at the opening peripheral edge of the oil hole 150E, so that the carburized concentration at the opening peripheral edge is suppressed from becoming excessively high, and the upper limit of the carbon concentration of the inclined surface 150F is set to 0.9 wt%. Thus, the link member 150 suppresses the generation of cementite at the opening peripheral edge of the oil hole 150E, and prevents the breakage of the cementite base point.

Thus, the link member 150 can prevent damage by improving the resistance of the portion of the oil hole 150F where stress concentration is likely to occur while suppressing the manufacturing cost. The inclined surfaces 150F may be provided on the opening peripheral edges of the oil holes 150E. However, in the connecting rod member 150, the crankshaft side serves as an input side for a bending load, and therefore, the inclined surface 150F is provided on the crankshaft side to define the carbon concentration.

Therefore, in the cross section shown in fig. 5, the length R from the intersection of the extension line LE of the inner surface of the oil hole 150E and the member surface to the inclined surface 150F of the link member 150 is preferably in the range of 0.05 to 0.2 mm. The length R can also be interpreted as a chamfer amount. Fig. 5 shows, as an example, a slant surface 150F inclined at an angle of 45 degrees with respect to the axis of the oil hole 150E.

That is, since the inclined surface 150F determines the area by defining the length R (the amount of chamfering), the function of suppressing the generation of cementite is ensured by setting the lower limit value to 0.05 mm. In addition, the inclined surface 150F can reliably obtain a higher carbon concentration than other portions by setting the upper limit value of the length R to 0.2 mm.

Further, the link member 150 may be a member having an arithmetic surface roughness Ra of the inclined surface 150F of 1.7 μm or less and a maximum height Ry of 9.8 μm or less as a more desirable embodiment.

The link member 150 can prevent the generation of an initial crack of the inclined surface 150F by defining the surface roughness of the inclined surface 150F and the upper limit of the maximum height. That is, if the arithmetic surface roughness Ra is larger than 1.7 μm, there is a possibility that damage may occur starting from the concave portions of the irregularities. In the case where there are fine protrusions having a maximum height Ry exceeding 9.8 μm, the carburized concentration may be concentrated on the protrusions during the carburizing treatment, and cementite may be generated, as described above with reference to the opening peripheral edge of the oil hole 150E.

Therefore, the connecting rod member 150 can prevent the damage from the recess as the starting point by defining the upper limits of the surface roughness and the maximum height of the inclined surface 150F of the oil hole 150E to smooth the surface, and prevent the damage from the cementite base point by preventing the concentration of the minute carbon concentration.

Further, the link member 150 may be formed such that the rockwell hardness of the inclined surface 150F is 58HRC or more as a more desirable embodiment.

That is, the inclined surface 150F can define the amount of retained austenite in the surface after the carburizing and quenching treatment by defining the hardness of the surface in addition to the definition of the carbon concentration described above. Therefore, the connecting rod member 150 improves the temper softening resistance, toughness, and bending fatigue strength around the oil hole 150E by defining the hardness, the amount of retained austenite, and the carbon concentration of the inclined surface 150F.

In addition, the link member 150 may be formed such that the grain boundary oxide layer on the surface of the inclined surface 150F has a thickness of 5 μm or less as a more desirable embodiment. In manufacturing such a connecting rod member 150, it is desirable that the carburizing process be a vacuum carburizing process as a manufacturing method including a step of performing the carburizing process.

In general, when a grain boundary oxide layer is generated by a carburizing process, the grain boundary oxide layer may serve as a base point of breakage. Since the link member 150 prevents the generation of an initial crack on the inclined surface 150F, it is desirable that at least the inclined surface 150F has no grain boundary oxide layer.

Therefore, in the production of the connecting rod member 150, by performing the vacuum carburizing treatment as the carburizing treatment, it is possible to suppress the generation of the grain boundary oxide layer at least on the inclined surface 150F, and to control the carbon concentration, the residual austenite amount, and the hardness while limiting the above. Thus, the link member 150 has a larger carbon concentration difference between the inclined surface 150F and the surface around the inclined surface 150F.

Example (embodiment)

Here, the link members of examples 1 to 12 and comparative examples 1 to 3 were manufactured by the following processing procedure. The material of the link member was SCr420H (JIS), and the amount of chamfering of the inclined surface (length R shown in fig. 5) was 0.1mm, except for comparative example 3. Comparative example 3 is an example without an inclined surface. Further, a tool mark (tool mark) generated when the oil hole is formed is removed by grinding. The tool mark may become a starting point of the breakage.