WO2015190117A1

WO2015190117A1 - Crankshaft of reciprocating engine

Info

Publication number: WO2015190117A1
Application number: PCT/JP2015/002958
Authority: WO
Inventors: 吉野　健; 訓宏薮野; 広一郎石原; 位直石井
Original assignee: 新日鐵住金株式会社
Priority date: 2014-06-12
Filing date: 2015-06-12
Publication date: 2015-12-17

Abstract

　A crankshaft (1) is provided with a journal part (J) as a rotational center axis, a pin part (P) eccentric from the journal part (J), and a crank arm part (A) joining the journal part (J) and the pin part (P). The arm part (A) includes a journal thrust part (Jt) and a pin thrust part (Pt). In the arm part (A), the maximum diametrical length (y) from the rotational center (CL) to the outer periphery of a pin top part (Apt) is less than the combined length of the crank radius (Rc) and the radius (Rpt) of the pin thrust part (Pt). The weight can thereby be reduced while the rigidity of the crank arm part is ensured, and the gravity center radius of the crank arm part can be dramatically reduced. Additionally, the crankshaft can be easily manufactured.

Description

Reciprocating engine crankshaft

The present invention relates to a crankshaft mounted on a reciprocating engine.

In reciprocating engines such as automobiles, motorcycles, agricultural machinery, and ships, a crankshaft is indispensable for converting the reciprocating motion of a piston in a cylinder into a rotational motion to extract power. Crankshafts are roughly classified into those manufactured by die forging and those manufactured by casting. In particular, when high strength and high rigidity are required, the former forged crankshaft having excellent characteristics is often used.

1A and 1B are diagrams schematically showing an example of a conventional crankshaft. FIG. 1A is a side view of the entire crankshaft, and FIG. 1B is a plan view when the crank arm portion is viewed from the pin portion side. Respectively. A crankshaft 1 illustrated in FIGS. 1A and 1B is mounted on a four-cylinder engine. The crankshaft 1 has five journal portions J1 to J5, four pin portions P1 to P4, a front portion Fr, a flange portion Fl, and eight crank arms connecting the journal portions J1 to J5 and the pin portions P1 to P4, respectively. Part (hereinafter also simply referred to as “arm part”) A1 to A8. Such a crankshaft 1 is a crankshaft of a four-cylinder-8-counterweight having counterweights on all eight arm portions A1 to A8.

Hereinafter, when each of the journal portions J1 to J5, the pin portions P1 to P4, and the arm portions A1 to A8 are collectively referred to, the reference numerals are “J” for the journal portion, “P” for the pin portion, and “P” for the arm portion. Also referred to as “A”. The pin portion P, the pair of arm portions A connected to the pin portion P, and the journal portion J connected to each of the arm portions A are collectively referred to as “slow”.

The journal part J, the front part Fr, and the flange part Fl are arranged coaxially with the rotation center CL of the crankshaft 1. Further, the pin portion P is arranged eccentric from the rotation center CL of the crankshaft 1 by a length that is half the piston stroke, that is, the length of the crank radius Rc. The journal portion J is supported by the engine block via a sliding bearing (also referred to as “metal”) and serves as a rotation center shaft. A large end portion of a connecting rod (hereinafter also referred to as “connecting rod”) is connected to the pin portion P via a sliding bearing, and a piston is connected to a small end portion of the connecting rod.

The arm part A is provided with a journal thrust part Jt concentrically with the journal part J, and the journal thrust part Jt is adjacent to the journal part J. The journal thrust part Jt mainly contributes to the axial positioning of the crankshaft 1 in the engine block. The arm portion A is provided with a pin thrust portion Pt concentrically with the pin portion P, and the pin thrust portion Pt is adjacent to the pin portion P. The pin thrust part Pt mainly contributes to the positioning of the connecting rod in the axial direction.

In recent years, reciprocating engines for automobiles in particular have been required to be lighter in order to improve fuel efficiency. For this reason, the crankshaft, which is a basic part of a reciprocating engine, is also required to be lighter. Examples of conventional techniques for reducing the weight of the crankshaft include the following.

Japanese Patent Application Laid-Open No. 2012-7726 (Patent Document 1) and Japanese Patent Application Laid-Open No. 2010-230027 (Patent Document 2) describe an arm portion in which a hole is formed on the surface on the journal portion side. The hole portion is recessed deeply and deeply toward the pin portion, and is formed on a straight line (hereinafter also referred to as “arm portion center line”) connecting the axis of the journal portion and the axis of the pin portion. In the arm part described in the document, the volume of the hole part is reduced in weight. The weight reduction of the arm part leads to a reduction in the weight of the counterweight, which in turn leads to a reduction in the weight of the entire crankshaft. Further, since the arm portion disclosed in the same document is maintained thick at both side portions in the vicinity of the pin portion sandwiching the arm portion center line, rigidity (torsional rigidity and bending rigidity) is also ensured.

JP 2012-7726 A JP 2010-230027 A

Since the crankshaft disclosed in

Patent Documents

1 and 2 has the above-mentioned unique shape of the arm portion, it is not easy to manufacture by a general manufacturing method. For example, in the manufacturing method using die forging, when a hole is formed on the surface of the arm portion in the die forging process, the die cutting gradient of the die is reversed at the portion corresponding to the hole, and the formed forging A situation occurs in which the material cannot be removed from the mold. For this reason, in the die forging process, a forged material is formed without forming a hole on the surface of the arm part, and after the deburring process, an additional process is required in which a punch is pushed into the surface of the arm part to form a hole. Become. Alternatively, after the deburring process, additional processing for forming the hole by machining using a drill or the like is required. Similarly, the manufacturing method by casting requires additional processing.

Also, when considering reducing the weight of the crankshaft, it is required not only to reduce the weight while ensuring the rigidity of the arm portion, but also to reduce the mass moment. In order to reduce the mass moment, the center of gravity radius of the arm portion may be reduced in consideration of appropriateness of static balance, dynamic balance, and balance ratio. However, in the crankshaft in which a hole is formed on the surface of the arm as described in

Patent Documents

1 and 2, there is a limit to reducing the center of gravity radius of the arm, and its technical innovation is strongly desired.

The present invention has been made in view of such circumstances, can reduce the weight while ensuring the rigidity of the arm portion, and can dramatically reduce the center-of-gravity radius of the arm portion. An object of the present invention is to provide a crankshaft of a reciprocating engine that can be easily manufactured.

A crankshaft of a reciprocating engine according to an embodiment of the present invention includes a journal part serving as a rotation center axis, a pin part eccentric with respect to the journal part, a crank arm part connecting the journal part and the pin part, Is provided. The crank arm portion includes a journal thrust portion and a pin thrust portion. Further, the crank arm portion is configured such that the maximum radial length from the rotation center to the outer periphery of the pin top portion is smaller than the crank radius plus the radius of the pin thrust portion.

In the above crankshaft, the crank arm portion has a configuration in which a maximum radial length from the rotation center to the outer periphery of the pin top portion coincides with a length obtained by adding the radius of the pin portion to the crank radius. can do.

In the above crankshaft, the top portion of the pin thrust portion is centered on the axis of the pin thrust portion with respect to an arm centerline connecting the axis of the journal portion and the axis of the pin portion. A configuration lacking within an angle range of ± 75 ° is preferable.

In the crankshaft described above, it is preferable that a linear oil hole is formed from the pin portion to the journal portion through the arm portion. In this case, the diameter of the oil hole is preferably 5 mm or less.

According to the crankshaft of the present invention, the volume is reduced at the pin top portion of the arm portion as compared with the conventional arm portion. Accordingly, it is possible to reduce the weight while ensuring the rigidity of the arm portion, and it is possible to dramatically reduce the center-of-gravity radius of the arm portion. Moreover, it can also be manufactured easily without requiring additional processing.

FIG. 1A is a diagram schematically showing an example of a conventional crankshaft, and shows a side view of the entire crankshaft. FIG. 1B is a diagram schematically showing an example of a conventional crankshaft, and shows a plan view when the crank arm portion is viewed from the pin portion side. FIG. 2A is a diagram schematically showing an example of the crankshaft of the first embodiment, and shows a side view of the entire crankshaft. FIG. 2B is a diagram schematically showing an example of the crankshaft of the first embodiment, and shows a plan view when the crank arm portion is viewed from the pin portion side. FIG. 3A is a diagram schematically illustrating an example of the crankshaft of the second embodiment, and shows a side view of the entire crankshaft. FIG. 3B is a diagram schematically showing an example of the crankshaft of the second embodiment, and shows a plan view when the crank arm portion is viewed from the pin portion side. FIG. 4 is a schematic view for explaining a chipped range of the top portion of the pin thrust portion in the crankshaft of each embodiment. FIG. 5 is a diagram schematically illustrating the correlation between the chipping range of the top portion of the pin thrust portion, the mass moment, and the torsional rigidity of the crankshaft of each embodiment. FIG. 6A is a schematic diagram showing a preferred mode of oil holes in the crankshaft of each embodiment, and shows a one-throw side view of the crankshaft. FIG. 6B is a schematic diagram showing a preferred aspect of the oil hole in the crankshaft of each embodiment, and shows a plan view when the crank arm portion is viewed from the pin portion side.

Hereinafter, embodiments of the crankshaft of the reciprocating engine of the present invention will be described in detail.

[First Embodiment]
2A and 2B are diagrams schematically illustrating an example of the crankshaft according to the first embodiment. FIG. 2A is a side view of the entire crankshaft, and FIG. 2B is a view of the crank arm portion as viewed from the pin portion side. Each of the plan views is shown. The crankshaft 1 illustrated in FIGS. 2A and 2B is mounted on a four-cylinder engine, similar to the conventional crankshaft 1 shown in FIGS. 1A and 1B. In the following, parts common to the conventional crankshaft 1 shown in FIGS. 1A and 1B are denoted by the same reference numerals, and redundant description will be omitted as appropriate.

2A and 2B, the arm portion A connects the journal portion J, which is the rotation center axis, and the pin portion P that is eccentric from the rotation center CL by the length of the crank radius Rc. The arm part A is provided with a journal thrust part Jt and a pin thrust part Pt. The journal thrust part Jt is adjacent to the journal part J and is concentric with the journal part J. The pin thrust portion Pt is adjacent to the pin portion P and is concentric with the pin portion P.

In the arm part A in the present embodiment, the maximum radial length y from the rotation center CL to the outer periphery of the pin top part Apt is smaller than the crank radius Rc plus the radius Rpt of the pin thrust part Pt. The maximum length y here is the length from the rotation center CL to the outer periphery of the pin top portion Apt of the arm portion A in the direction along the arm portion center line Ac in a cross section perpendicular to the rotation center CL of the crankshaft 1. That's it. The arm part center line Ac is a straight line that connects the axis (rotation center CL) of the journal part J and the axis of the pin part P. As a result, the arm portion A enters a state in which the outline of the outer periphery of the pin top portion Apt enters the region of the top portion of the pin thrust portion Pt and a part of the pin thrust portion Pt (the region of the top portion) is missing.

The volume of the arm portion A having such a shape is reduced in the pin top portion Apt including the region of the top portion of the pin thrust portion Pt as compared with the conventional arm portion A. Since the volume change of the pin top part Apt of the arm part A does not affect the rigidity (torsional rigidity and bending rigidity), the rigidity of the arm part A can be ensured. Further, the portion where the volume of the arm part A is reduced is the pin top part Apt farthest from the rotation center CL. For this reason, the weight reduction in the pin top part Apt accompanying the volume reduction can dramatically reduce the center-of-gravity radius of the arm part, and as a result, the mass moment can be reduced. Accordingly, the weight of the counterweight can be greatly reduced based on the appropriateness of the static balance, dynamic balance, and balance ratio. As a result, the overall weight of the crankshaft 1 is significantly reduced.

Moreover, the crankshaft 1 of the present embodiment can be easily manufactured by a general forging or casting manufacturing method. This is because the arm portion A in the present embodiment has a shape in which the contour of the outer periphery of the pin top portion Apt has just entered the region of the top portion of the pin thrust portion Pt, so that the situation where the die cutting gradient becomes a reverse gradient does not occur. For this reason, the additional process like the case where the crankshaft disclosed by the said

patent documents

1 and 2 is manufactured is not required at all.

[Second Embodiment]
3A and 3B are diagrams schematically showing an example of the crankshaft according to the second embodiment. FIG. 3A is a side view of the entire crankshaft, and FIG. 3B is a view of the crank arm portion as viewed from the pin portion side. Each of the plan views is shown. The crankshaft 1 illustrated in FIGS. 3A and 3B is a modification of the crankshaft 1 of the first embodiment shown in FIGS. 2A and 2B. Below, the same code | symbol is attached | subjected to the part which is common in the crankshaft 1 of 1st Embodiment shown to the said FIG. 2A and FIG. 2B, and the overlapping description is abbreviate | omitted suitably.

In the arm portion A in the present embodiment, the maximum radial length y from the rotation center CL to the outer periphery of the pin top portion Apt coincides with the crank radius Rc plus the radius Rp of the pin portion P. As a result, as in the first embodiment, the arm portion A has a contour of the outer periphery of the pin top portion Ap entering the region of the top portion of the pin thrust portion Pt and a part of the pin thrust portion Pt (the region of the top portion). ) Is missing. In particular, in the pin top part Apt of the arm part A, the pin thrust part Pt does not exist as long as it is on the arm part center line Ac.

Even in the arm portion A having such a shape, the volume of the pin top portion Apt including the region of the top portion of the pin thrust portion Pt is reduced as compared with the conventional arm portion A. The same effect is produced.

[Suitable matters in the first and second embodiments]
(1) Top notch range of pin thrust part FIG. 4 is a schematic diagram for explaining the notch range of the top part of the pin thrust part in the crankshaft of each embodiment. As shown in FIG. 4, the situation where the top portion of the pin thrust portion Pt is missing in the range of an angle of ± θ ° centered on the axis of the pin thrust portion Pt with respect to the arm center line Ac is examined. To do.

FIG. 5 is a diagram schematically showing the correlation between the chipping range of the top portion of the pin thrust portion, the mass moment, and the torsional rigidity of the crankshaft of each embodiment. The correlation shown in FIG. 5 summarizes the results of FEM analysis. In the FEM analysis, the mass range and the torsional rigidity of the arm portion were calculated by changing various chipping ranges (angle ± θ ° range) of the top portion of the pin thrust portion shown in FIG.

As shown in FIG. 5, the mass moment of the arm portion decreases as the chipped range (angle ± θ ° range) of the top portion of the pin thrust portion increases. Particularly, the tendency of decreasing the mass moment of the arm portion is remarkable until the chipped portion of the top portion of the pin thrust portion is in the range of angle ± 75 °. On the other hand, the torsional rigidity of the arm part does not change until the chipping range of the top part of the pin thrust part is within the range of angle ± 75 °, and significantly decreases when the chipping range exceeds the range of angle ± 75 °.

For this reason, the notch range of the top portion of the pin thrust portion is preferably within an angle range of ± 75 ° from the viewpoint of simultaneously ensuring the rigidity of the arm portion and reducing the mass moment. It should be noted that if the chipping range of the top portion of the pin thrust part is too small, the effect of reducing the mass moment is not effectively exhibited, and therefore the chipping range preferably exceeds the range of angle ± 3 °.

(2) Aspect of oil hole due to chipping of top part of pin thrust part As described above, a part of the pin thrust part is missing in the crankshaft of each embodiment. Since the chipping of the pin thrust portion is limited to the region of the top portion, there is no hindrance to the positioning of the connecting rod in the axial direction. However, there are the following concerns.

The connecting rod is connected to the pin portion of the crankshaft via a sliding bearing, and lubricating oil exists between the outer peripheral surface of the pin portion and the sliding bearing to ensure the lubricity of both. Lubricating oil is supplied to the pin part through oil holes formed from the pin part to the journal part through the arm part. At that time, the lubricating oil is first discharged from the engine block toward the journal portion by the driving force of the oil pump. Lubricating oil discharged toward the journal part becomes lubricating oil between the outer peripheral surface of the journal part and the sliding bearing of the engine block, and enters the oil hole from the inlet of the oil hole opened in the outer peripheral surface of the journal part. Inflow. The lubricating oil that has flowed into the oil hole flows out of the outlet of the oil hole that opens in the outer peripheral surface of the pin portion due to the driving force of the oil pump and the centrifugal force that accompanies the rotation of the crankshaft. Supplied between the bearings.

Here, when a part of the pin thrust part is missing like the crankshaft of each of the above-described embodiments, the lubricating oil existing between the outer peripheral surface of the pin part and the sliding bearing is a part where the pin thrust part is missing. There is a risk of leakage. When the amount of leakage of the lubricating oil is large, the driving force of the oil pump is increased to compensate for the amount of leakage. As a result, the fuel consumption of the engine deteriorates. This is because the driving force of the oil pump is brought about by utilizing the rotational force of the crankshaft.

Therefore, in the crankshaft of each of the above-described embodiments, it is desirable to reduce the supply amount of the lubricating oil to the pin portion in order to suppress an increase in driving force of the oil pump and suppress deterioration in fuel consumption. As a measure for this, it is preferable to limit the mode of the oil hole as follows.

6A and 6B are schematic views showing a preferred aspect of the oil hole in the crankshaft of each embodiment, FIG. 6A is a side view of one throw of the crankshaft, and FIG. 6B is the pin side of the crank arm portion. Plan views when viewed from above are shown.

As shown in FIGS. 6A and 6B, in the crankshaft of each embodiment, a linear oil hole 2 is formed from the pin portion P to the journal portion J through the arm portion A. This oil hole 2 is called I-type, and one end serving as an outlet opens to the outer peripheral surface of the top portion of the pin portion P, and the other end serving as an inlet opens to the outer peripheral surface of the journal portion J at one location. On the other hand, a general-purpose oil hole called V-type is the same as I-type in that one end serving as an outlet opens to the outer peripheral surface of the top portion of the pin portion P, but the other end serving as an inlet is a journal. There are two openings in the outer peripheral surface of the part J.

In the crankshaft of each embodiment, if the I-type oil hole 2 is employed, the inlet of the oil hole 2 is one place. Therefore, the inflow place of the lubricating oil into the oil hole 2 is compared with the V-type oil hole. Decrease. For this reason, if the I-type oil hole 2 is employed, the supply amount of the lubricating oil to the pin portion P can be reduced. Thereby, an increase in driving force of the oil pump can be suppressed and deterioration of fuel consumption can be suppressed.

Furthermore, in the crankshaft of each embodiment, the diameter of the oil hole 2 is preferably limited to 5 mm or less. This is because the supply amount of the lubricating oil to the pin portion P can be further reduced. However, if the diameter of the oil hole 2 is too small, the supply amount of the lubricating oil to the pin portion P may be insufficient. Therefore, the diameter is preferably 3 mm or more.

Others The present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the present invention. For example, the crankshaft of the present invention is intended for a crankshaft mounted on any reciprocating engine. That is, the number of cylinders of the engine may be any of one cylinder, two cylinders, three cylinders, six cylinders, eight cylinders, and ten cylinders in addition to four cylinders, or may be larger. The arrangement of the engine cylinders is not particularly limited, such as an in-line arrangement, a V-type arrangement, and an opposed arrangement. The fuel for the engine is not limited to gasoline, diesel, biofuel, etc. The engine also includes a hybrid engine formed by combining an internal combustion engine and an electric motor.

The present invention can be effectively used for a crankshaft mounted on any reciprocating engine.

1: crankshaft,
J, J1 to J5: Journal part, Jt: Journal thrust part,
P, P1 to P4: Pin part, Pt: Pin thrust part,
Fr: front part, Fl: flange part,
A, A1-A8: Crank arm part,
Ac: arm part center line, Apt: pin top part,

y: maximum length,
CL: center of rotation, Rc: crank radius,
Rpt: Pin thrust radius, Rp: Pin radius,
2: Oil hole

Claims

A journal part which becomes a rotation center axis;
A pin part eccentric with respect to the journal part;
Including a journal thrust part and a pin thrust part, and comprising a crank arm part connecting the journal part and the pin part,
The crankshaft of a reciprocating engine, wherein the crank arm portion has a maximum radial length from the center of rotation to the outer periphery of the pin top portion that is smaller than the crank radius plus the radius of the pin thrust portion.
The crankshaft according to claim 1, wherein
The crankshaft of the reciprocating engine, wherein the crank arm portion has a maximum radial length from the rotation center to the outer periphery of the pin top portion that matches a length obtained by adding the radius of the pin portion to the crank radius.
The crankshaft according to claim 1 or 2,
The top portion of the pin thrust portion is within a range of an angle of ± 75 ° about the axis of the pin thrust portion with respect to an arm center line connecting the axis of the journal portion and the axis of the pin portion. The crankshaft of the reciprocating engine that is missing inside.
The crankshaft according to any one of claims 1 to 3,
A crankshaft of a reciprocating engine, wherein a linear oil hole is formed from the pin part to the journal part through the arm part.
The crankshaft according to claim 4, wherein
A crankshaft of a reciprocating engine, wherein the oil hole has a diameter of 5 mm or less.