JP2010014142A - Crankshaft - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a crankshaft reducing bearing hitting noises involved in torsional vibration, and adapted to an internal combustion engine of an in-line four-cylinder type. <P>SOLUTION: The crankshaft 1 has five journal portions. Of these journal portions, the fourth journal portion 2D, which is located in the fourth position from the starting point of the end of the side opposite to the flywheel-mounted side, is structured in a hollow shape in such a way that its stiffness in the second direction D2 perpendicular to the first direction D1 becomes lower than that in the first direction D1 perpendicular to each of the axis of rotation Ax and the center line CL of a crank pin 3. The journal portions other than the fourth journal portion 2D are structured in a solid state. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a crankshaft applied to an in-line four-cylinder internal combustion engine.

  A crankshaft applied to an in-line four-cylinder internal combustion engine is configured as a so-called single plane type in which the phases of the crankpins are shifted by 180 degrees and the center lines of the four crankpins are located in the same plane. As such a crankshaft, the journal part has a hollow structure, and ribs are provided in the hollow part to increase rigidity, thereby reducing the bearing hitting sound of the journal part due to bending vibration while reducing the weight. Known (Patent Document 1). Also known is a technique in which the crankshaft is configured in the same manner as in Patent Document 1 to reduce the uneven wear of the sliding portion of the crankpin and the journal portion, and to suppress the generation of noise due to the uneven wear. (Patent Document 2). In addition, Patent Documents 3 to 5 exist as prior art documents related to the present invention.

Japanese Patent Publication No. 3-40247 Japanese Utility Model Publication No. 63-20520 JP-A-7-139538 JP 2006-125446 A Japanese Utility Model Publication No. 61-133115

  Generally, each journal portion is rotatably supported by a cylinder block of an internal combustion engine with a sliding bearing interposed. This bearing has a half member on the cylinder block side located on the upper side in the center line direction of the cylinder with respect to the rotation axis of the journal portion, and a half member on the crank cap side located on the lower side in the center line direction of the cylinder. An oil groove extending in the circumferential direction is formed on the inner circumferential surface of the upper half member that is combined and extends so as to avoid both ends in the circumferential direction. It is known that due to the presence of the oil groove, the oil surface pressure of the lubricating oil generated between the journal portion and the bearing exhibits a distribution in which both end portions are higher than other portions.

  Incidentally, the vibration of the crankshaft generates torsional vibration in addition to bending vibration. In the case of torsional vibration of a crankshaft applied to an in-line four-cylinder internal combustion engine, the vibration level of the fourth fourth journal part is the highest starting from the end opposite to the side on which the flywheel is mounted. found. The vibration direction of the fourth journal portion vibrates in the upper left direction when viewed from the end portion side serving as the starting point with reference to the center line direction of the cylinder.

  When such torsional vibration occurs, the vibration direction of the fourth journal portion is in the upper left direction and crosses the oil groove of the upper half member. For this reason, the fourth journal portion hits a portion where the oil surface pressure is low due to the torsional vibration of the fourth journal portion, and there is a problem that the bearing hitting sound of the fourth journal portion hitting the bearing is increased.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a crankshaft that is applied to an in-line four-cylinder internal combustion engine that can reduce bearing noise caused by torsional vibration.

  The crankshaft of the present invention is applied to an in-line four-cylinder internal combustion engine, and is a crankshaft in which the center lines of the four crankpins are located in the same plane, the halving member on the cylinder block side and the crankcap side A bearing which is combined with a half member and has an oil groove extending in the circumferential direction so as to avoid both ends in the circumferential direction of the half member on the inner circumferential surface of the half member on the cylinder block side is interposed. In this state, five journal parts rotatably supported by the cylinder block around the rotation axis are provided, and the end of the five journal parts opposite to the side on which the flywheel is mounted is a starting point. The fourth journal portion located at the fourth position is orthogonal to the first direction rather than the rigidity in the first direction orthogonal to the rotation axis and the center line of the crankpin. It is configured in a hollow shape so as to reduce the rigidity in the second direction, and the remaining journal portions other than the fourth journal portion are configured in a solid shape, thereby solving the above-described problem (claims). Item 1).

  According to this crankshaft, the fourth journal portion is hollow so that the rigidity in the second direction orthogonal to this direction is lower than the rigidity in the first direction orthogonal to each of the rotation axis and the center line of the crankpin. The other journal parts are configured in a solid state. With such a configuration, when the crankshaft of the present invention is incorporated in an internal combustion engine, the vibration direction of the fourth journal portion during torsional vibration is when all the journal portions are configured to be uniformly hollow or solid. In comparison, it has been found that the direction approaches the direction perpendicular to the cylinder center line (or the horizontal direction when the cylinder center line direction matches the vertical direction). Thereby, the vibration direction of the fourth journal portion can be brought close to both end portions of the half member in which no oil groove is formed. Both end portions of the half member have higher oil surface pressure than the other portions. For this reason, the collision of the fourth journal portion with the bearing, which is caused by the torsional vibration, can be received at the portion where the oil surface pressure is relatively high. As a result, it is possible to reduce bearing hitting sound caused by the fourth journal portion hitting the bearing.

  The fourth journal portion may have any shape as long as the rigidity in the second direction is lower than that in the first direction. For example, an elliptical hollow portion may be provided in the fourth journal portion, and the thickness of the fourth journal portion in the first direction may be smaller than the thickness in the second direction. A hollow portion may be formed in the fourth journal portion, and a rib extending in the first direction may be provided in the hollow portion. In this case, since the rigidity in the first direction is reinforced by the rib provided in the hollow portion, the rigidity in the second direction can be made lower than the rigidity in the first direction.

  As described above, according to the present invention, the fourth journal is configured such that the rigidity in the second direction orthogonal to this direction is lower than the rigidity in the first direction orthogonal to each of the rotation axis and the center line of the crankpin. Since the part is formed in a hollow shape and each other journal part is formed in a solid form, the vibration direction of the fourth journal part during torsional vibration is determined by the both end parts of the half member in which no oil groove is formed. Can be approached. Thereby, the collision with respect to the bearing of a 4th journal part can be received in the part whose oil surface pressure is relatively high. As a result, it is possible to reduce bearing hitting sound caused by the fourth journal portion hitting the bearing.

  FIG. 1 shows a crankshaft according to an embodiment of the present invention. The crankshaft 1 is applied to an in-line four-cylinder internal combustion engine, and is used by being rotatably incorporated in the internal combustion engine. The crankshaft 1 includes five journal portions 2 arranged in the direction of the rotation axis Ax, four crankpins 3 positioned between the journal portions 2, a crank arm 4 connecting the journal portion 2 and the crankpin 3, A balance weight 5 extending from each crank arm 4 to the opposite side of the crank pin 3 is provided. These components of the crankshaft 1 are integrally formed by casting. As can be seen from FIG. 1, the crankshaft 1 is a single plane type in which the phases of the crankpins 3 are shifted by 180 degrees, and the center line CL of each crankpin 3 is located in the same plane (in the plane of FIG. 1). It is configured as a full counter crankshaft. When the crankshaft 1 is incorporated into the internal combustion engine, a flywheel (not shown) is mounted on the right end 1a in FIG. Hereinafter, in order to distinguish the five journal parts 2 from each other, the first journal part 2A is the first and the second is the first one, starting from the end 1b on the side opposite to the side on which the flywheel is mounted (left side in FIG. 1). In some cases, the second journal part 2B, the third journal part 2C, the fourth journal part 4D, the fifth journal part 4E, and the fifth journal part 4E may be displayed.

  FIG. 2 is a view showing a state in which the crankshaft of FIG. 1 is incorporated in an internal combustion engine. FIG. 2 shows a cross section of the peripheral configuration of the fourth journal portion 2D. The peripheral configuration of the journal portions 2A to 2C and 2E other than the fourth journal portion 2D is substantially the same as that in FIG. Each journal portion 2 is sandwiched between a journal receiver 10a formed in a cylinder block 10 of the internal combustion engine and a crank cap 11, and a cylinder block around a rotation axis Ax with a bearing 12 interposed therebetween. 10 is rotatably supported. The crank cap 11 is fixed to the cylinder block 10 by fastening means such as a bolt (not shown).

  The bearing 12 is configured as a well-known sliding bearing of a half type. The bearing 12 is a combination of a half member 15 on the cylinder block 10 side and a half member 16 on the crank cap 11 side, which is divided into two parts on the basis of a center line direction (vertical direction in FIG. 2) of a cylinder (not shown). It is mounted in the state that was done. An oil groove 18 having a predetermined width extending in the circumferential direction is formed on the inner circumferential surface of the upper half member 15 so as to avoid both end portions 15a in the circumferential direction. The half member 15 is formed with an oil hole 19 that opens into the oil groove 18. Between the journal portion 2 and the bearing 12, the lubricating oil is provided from the cylinder block 10 side through the oil hole 19. Is supplied. The cylinder block 10 is provided with a predetermined oil passage for supplying lubricating oil to the oil hole 19, but the illustration is omitted.

  3 shows a cross section of the fourth journal portion 2D taken along line III-III in FIG. 1, and FIG. 4 shows a cross section of the third journal portion 2C taken along line IV-IV in FIG. As shown in FIG. 3, the 4th journal part 2D is comprised by the hollow shape hollowed, and the 3rd journal part 2C is comprised by the solid state which is not thinned as shown in FIG. Note that the journal portions 2A, 2B, and 2E, whose cross-sectional illustration is omitted, are configured in a solid state in the same manner as the third journal portion 2C shown in FIG. As shown in FIG. 3, a hollow portion 20 is formed in the fourth journal portion 2 </ b> D, and in the hollow portion 20, a first direction orthogonal to each of the rotation axis Ax and the center line CL of the crankpin 3. Ribs 21 extending in D1 are formed. The rib 21 also extends in the direction of the rotation axis Ax (direction perpendicular to the paper surface) so as to completely separate the hollow portion 20. For this reason, the 4th journal part 2D has the rigidity of the 2nd direction D2 orthogonal to a 1st direction lower than the rigidity of the 1st direction D1. On the other hand, since the journal portions 2A to 2C and 2E other than the fourth journal portion 2D are configured in a solid state, the respective stiffnesses in the first direction D1 and the second direction D2 are substantially equal. In addition, the rigidity said here means bending rigidity.

  FIG. 5 is an explanatory view for explaining the operation of the crankshaft 1 when the crankshaft 1 is operated by being incorporated in an internal combustion engine, and shows the peripheral configuration of the fourth journal portion 2D. In FIG. 5, the center line direction of the cylinder of the internal combustion engine is defined as the Y direction, and the direction orthogonal thereto is defined as the X direction. Needless to say, when the Y direction, which is the center line direction of the cylinder, is made to coincide with the vertical direction, the X direction becomes the horizontal direction. Further, P in the figure indicates the distribution of the oil surface pressure of the lubricating oil during operation of the internal combustion engine.

  As described above, it has been found that the crankshaft applied to the in-line four-cylinder internal combustion engine also generates torsional vibration in addition to bending vibration, and the vibration level of the torsional vibration is the highest in the fourth journal portion. . In the crankshaft 1 of this embodiment, the rigidity of the fourth journal part 2D is lower in the second direction D2 than the first direction D1, and the rigidity of the other journal parts is substantially equal in these directions. As a result, as shown in FIG. 5, the vibration direction F of the fourth journal portion 2 </ b> D approaches the X direction as compared with the comparative example in which all the journal portions are configured uniformly in a hollow shape or a solid shape. In other words, in the crankshaft 1, the inclination of the vibration direction of the fourth journal portion 2D with respect to the X direction is smaller than that in the comparative example. Thereby, the vibration direction of the fourth journal portion 2D can be brought close to both end portions 15a of the half member 15 in which the oil groove 18 is not formed. As is apparent from the distribution P in FIG. 5, the oil surface pressure of the lubricating oil is higher at both ends 15a of the half member 15 than at the other portions. For this reason, the collision of the fourth journal portion 2D with the bearing 12 caused by the torsional vibration can be received at a portion where the oil surface pressure is relatively high. Thereby, the bearing sound caused by the fourth journal portion 2D hitting the bearing 12 can be reduced.

  The present invention is not limited to the above embodiments, and can be implemented in various forms within the scope of the gist of the present invention. The fourth journal portion according to the present invention is not limited to the form shown in FIG. 3, and may be various forms as long as it is hollowed out and has a rigidity in the second direction lower than the rigidity in the first direction. May be realized. FIG. 6 is a cross-sectional view showing another form of the fourth journal portion. An elliptical hollow portion 30 is formed in the fourth journal portion 2D ′ of FIG. 6, and the thickness t1 in the first direction D1 is smaller than the thickness t2 in the second direction D2. Accordingly, the crankshaft having the fourth journal portion 2D ′ has the same effect as the crankshaft 1 shown in FIG. 1 and the like because the rigidity in the second direction D2 is lower than the rigidity in the first direction D1. Can do.

The figure which showed the crankshaft which concerns on one form of this invention. The figure which showed the state in which the crankshaft of FIG. 1 was integrated in the internal combustion engine. Sectional drawing of the 4th journal part regarding the III-III line of FIG. Sectional drawing of the 3rd journal part regarding the IV-IV line of FIG. Explanatory drawing explaining the effect | action at the time of driving | operating by incorporating the crankshaft of FIG. 1 in an internal combustion engine. Sectional drawing which showed the other form of the 4th journal part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Crankshaft 1b End part 2A-2E on the opposite side to the side where a flywheel is mounted Journal part 3 Crank pin 10 Cylinder block 11 Crank cap 12 Bearing 15 Half member 15a End part 16 Half member 18 Oil groove 20 Hollow part 21 Rib 30 Hollow portion Ax Rotation axis CL Centerline of crank pin D1 First direction D2 Second direction

Claims (2)

A crankshaft which is applied to an in-line four-cylinder internal combustion engine and whose center lines are located in the same plane,
The cylinder block-side half member and the crank cap-side half member are combined, and the inner circumferential surface of the cylinder block-side half member is arranged so as to avoid both ends in the circumferential direction of the half member. Including five journal portions rotatably supported by the cylinder block around the rotation axis, with a bearing formed with an oil groove extending in the direction interposed,
Of the five journal parts, the fourth journal part located fourth from the end opposite to the side on which the flywheel is mounted is orthogonal to the rotation axis and the center line of the crank pin. It is configured in a hollow shape so that the rigidity in the second direction orthogonal to the first direction is lower than the rigidity in the first direction, and the remaining journal parts other than the fourth journal part are configured in a solid shape. Crankshaft characterized by being made.   The crankshaft according to claim 2, wherein a hollow portion is formed in the fourth journal portion, and a rib extending in the first direction is provided in the hollow portion.

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