WO2016021201A1 - レシプロエンジンのクランク軸 - Google Patents
レシプロエンジンのクランク軸 Download PDFInfo
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- WO2016021201A1 WO2016021201A1 PCT/JP2015/003952 JP2015003952W WO2016021201A1 WO 2016021201 A1 WO2016021201 A1 WO 2016021201A1 JP 2015003952 W JP2015003952 W JP 2015003952W WO 2016021201 A1 WO2016021201 A1 WO 2016021201A1
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- crankshaft
- cross
- sectional
- arm portion
- section
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
- F16C3/00—Shafts; Axles; Cranks; Eccentrics
- F16C3/04—Crankshafts, eccentric-shafts; Cranks, eccentrics
- F16C3/06—Crankshafts
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
- F16C3/00—Shafts; Axles; Cranks; Eccentrics
- F16C3/04—Crankshafts, eccentric-shafts; Cranks, eccentrics
- F16C3/06—Crankshafts
- F16C3/08—Crankshafts made in one piece
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
- F16C3/00—Shafts; Axles; Cranks; Eccentrics
- F16C3/04—Crankshafts, eccentric-shafts; Cranks, eccentrics
- F16C3/20—Shape of crankshafts or eccentric-shafts having regard to balancing
Definitions
- the present invention relates to a crankshaft mounted on a reciprocating engine such as an automobile engine, a marine engine, or a general-purpose engine such as a generator.
- crankshafts are roughly classified into those manufactured by die forging and those manufactured by casting.
- the former type forged crankshaft excellent in strength and rigidity is often used for a multi-cylinder engine having two or more cylinders.
- FIG. 1 is a side view schematically showing an example of a general multi-cylinder engine crankshaft.
- the crankshaft 1 shown in FIG. 1 is mounted on a four-cylinder engine, and includes five journals J1 to J5, four pins P1 to P4, a front part Fr, a flange Fl, and journals J1 to J5.
- eight crank arm portions (hereinafter, also simply referred to as "arm portions”) A1 to A8 that respectively connect the pin and the pin portions P1 to P4.
- the crankshaft 1 has a counterweight portion (hereinafter, also simply referred to as a "weight portion”) W1 to W8 integrally formed on all eight arm portions A1 to A8, and a 4-cylinder-8-piece counterweight crankshaft It is called.
- the journal portion J, the front portion Fr and the flange portion Fl are disposed coaxially with the rotation center of the crankshaft 1.
- the pin portion P is eccentrically disposed from the rotation center of the crankshaft 1 by a half distance of the piston stroke.
- the journal portion J is supported on the engine block by a slide bearing and serves as a rotation center axis.
- a slide bearing connects a large end of a connecting rod (hereinafter also referred to as a "con-rod”) to the pin portion P, and a piston is connected to a small end of the connecting rod by a piston pin.
- Lubricating oil is present in the bearing that supports the journal portion of the crankshaft. According to the elastic deformation of the crankshaft, the oil film pressure and the oil film thickness in the bearing change in correlation with the bearing load and the axial center locus of the journal portion. Furthermore, depending on the surface roughness of the journal portion of the bearing and the surface roughness of the bearing metal, not only oil film pressure occurs but also local metal contact also occurs. Ensuring oil film thickness is important to prevent bearing seizure due to oil shortage and to prevent local metal contact. It is because it affects the fuel efficiency performance.
- the elastic deformation accompanying the rotation of the crankshaft and the axial center locus of the journal portion moving in the clearance in the bearing affect the engine vibration (mount vibration) to cause a shift of the rotation center. Further, the vibration is transmitted to the vehicle body to affect noise in the passenger compartment, ride comfort and the like.
- crankshaft In order to improve such engine performance, the crankshaft is required to be high in rigidity and difficult to deform. In addition to this, the weight reduction of the crankshaft is required.
- a load of in-cylinder pressure (combustion pressure in the cylinder) is loaded on the crankshaft, and a load of rotational centrifugal force is loaded on the other.
- main specifications such as the diameter of the journal, the diameter of the pin, the piston stroke and the like are determined.
- the shape design of the arm portion becomes the design area left. For this reason, it is first important to improve both the torsional rigidity and the bending rigidity by the shape design of the arm portion.
- the arm portion referred to here is strictly an oval shaped portion limited to the region connecting the journal portion and the pin portion, and does not include the portion of the region of the counterweight portion.
- the crankshaft requires a balanced mass balance of static and dynamic balance. The reason is that it is possible to perform smooth rotation as a rotating body kinetically. In order to balance these static balance and dynamic balance, it is important to adjust the mass on the weight side in consideration of the weight reduction with respect to the mass on the arm side determined from the requirements of bending rigidity and torsional rigidity. It becomes.
- the static balance is adjusted so that the sum of all of the mass moment (mass ⁇ center of gravity) of each portion of the arm portion and the weight portion becomes zero.
- Dynamic balance is based on one point with the rotational axis of the crankshaft, and the distance in the axial direction from the reference point to the center of gravity of each part is multiplied by the mass moment of each part (mass ⁇ center of gravity ⁇ axial direction distance ), It is adjusted so that all these sums become zero.
- the balance ratio is adjusted to balance the combustion pressure load within one throw (the area of the crankshaft corresponding to one cylinder).
- the balance ratio is the ratio of the mass moment on the weight portion side to the mass moment on the arm portion side including the pin portion of the crankshaft (strictly, also including a part of the connecting rod).
- the balance ratio is adjusted to be within a certain range.
- Patent Document 1 is a straight line connecting the axis of the journal and the axis of the pin on the surface of the arm on the side of the pin and the surface on the side of the journal An arm portion provided with a concentrated and greatly recessed concave groove on the line (also referred to as “line”) is disclosed.
- the arm portion disclosed in Patent Document 1 aims to reduce the weight and improve the rigidity.
- the concave groove on the surface on the journal side contributes to weight reduction due to the reduction of mass, and the thick part around this concave groove contributes to the improvement of the torsional rigidity.
- improvement in bending rigidity can not be expected much.
- JP-A-2004-538429 discloses an arm portion provided with a large deep recessed hole on the center line of the arm portion on the surface of the arm portion on the side of the journal portion.
- the arm portions disclosed in Patent Documents 2 to 5 also achieve weight reduction and improvement in torsional rigidity. However, due to the presence of a large and deeply recessed hole on the center line of the arm, the bending rigidity actually decreases.
- the present invention has been made in view of such circumstances, and it is an object of the present invention to provide a crankshaft of a reciprocating engine which can realize weight reduction of the crankshaft and improvement in torsional rigidity and bending rigidity.
- a crankshaft of a reciprocating engine which is an embodiment of the present invention is It has a journal portion which is a rotation center shaft, a pin portion eccentric to the journal portion, a crank arm portion connecting the journal portion and the pin portion, and a counterweight portion integral with the crank arm portion.
- the crankshaft is mounted on a reciprocating engine.
- a recess is formed along the edge on the inner side of each edge along the contour of the surface.
- the recess may be connected at the position of the rotation center of the crankshaft.
- the concave portion may be connected at a position closer to the pin portion than the rotational center of the crankshaft.
- the recess may be connected along the contour of the journal at a position closer to the counterweight than the rotational center of the crankshaft.
- the recess be configured to be symmetrical with respect to a straight line connecting an axial center of the journal portion and an axial center of the pin portion.
- the recess is formed on the surface on the pin portion side of the arm portion.
- the edges on both sides of the arm portion are thickened, and the inner side is thinned by the recess.
- the center part inside the recess is thickened, weight reduction of the crankshaft and improvement in torsional rigidity and bending rigidity can be realized.
- FIG. 1 is a side view schematically showing an example of a general multi-cylinder engine crankshaft.
- FIG. 2 is a schematic view for explaining an evaluation method of bending rigidity of the arm portion.
- FIG. 3 is a schematic view for explaining an evaluation method of the torsional rigidity of the arm portion, and FIG. 3 (a) is a side view of one throw and FIG. 3 (b) is a front view in the axial direction. It shows each.
- FIG. 4 is a view showing a typical example in which the arm portion is regarded as a simple disk from the viewpoint of material mechanical torsional rigidity, and FIG. 4 (a) shows a rectangular cross-sectional disk, FIG. ) Shows a convex cross-sectional disc, and FIG.
- FIG. 4 (c) shows a concave cross-sectional disc, respectively.
- FIG. 5 is a view showing a typical example where the cross-sectional shape of the arm portion is simplified from the viewpoint of material mechanical rigidity and the arm portion is regarded as a simple beam, and FIG. FIG. 5 (b) shows a convex cross-sectional beam, and FIG. 5 (c) shows a concave cross-sectional beam.
- FIG. 6 is a diagram summarizing the magnitude relation between the sectional second moment and the pole second moment directly related to the bending rigidity and the torsional rigidity according to the sectional shape.
- FIG. 7 is a view schematically showing an example of the arm portion shape in the crankshaft of the first embodiment, and FIG.
- FIG. 7 (a) is a front view in an axial direction from the pin portion side; 7A shows a sectional view taken along the line AA, FIG. 7C shows a sectional view taken along the line BB, FIG. 7D shows a sectional view taken along the line CC, and FIG. 7E shows a sectional view taken along the line DD.
- FIG. 8 is a view schematically showing an example of the shape of the arm portion in the crankshaft of the second embodiment, and FIG. 8 (a) is a front view in an axial direction from the pin portion side. 8 shows an EE cross sectional view, FIG. 8C shows an FF cross sectional view, FIG. 8D shows a GG cross sectional view, and FIG. 8E shows an HH cross sectional view.
- FIG. 8 shows an EE cross sectional view
- FIG. 8C shows an FF cross sectional view
- FIG. 8D shows a GG cross sectional view
- FIG. 8E shows an HH cross sectional view.
- FIG. 9 is a view schematically showing an example of the shape of the arm portion in the crankshaft of the third embodiment, and FIG. 9 (a) is a front view in an axial direction from the pin portion side.
- 9 shows an I-I cross-sectional view
- FIG. 9C shows a J-J cross-sectional view
- FIG. 9D shows a K-K cross-sectional view
- FIG. 9E shows an L-L cross-sectional view.
- FIG. 10 is a view schematically showing an example of an arm portion shape in the crankshaft of the fourth embodiment
- FIG. 10 (a) is a front view in an axial direction from the pin portion side; 10) shows an MM sectional view
- FIG. 10 (c) shows an NN sectional view
- FIG. 10 (d) shows an OO sectional view
- FIG. 10 (e) shows a PP sectional view.
- crankshaft of the reciprocating engine of the present invention is explained in full detail about the crankshaft of the reciprocating engine of the present invention.
- FIG. 2 is a schematic view for explaining a method of evaluating the bending stiffness of the arm portion.
- the load F of the combustion pressure due to the explosion in the cylinder is applied to the pin portion P via the connecting rod.
- the journals J at both ends are supported by the bearings at each throw, the load F is transmitted from the pin P to the journal bearings via the arm A.
- arm part A will be in the load loading state of 3-point bending, and bending moment M will act on arm part A.
- a compressive stress is generated in the arm portion A on the outer side (journal portion J side) in the plate thickness direction
- a tensile stress is generated on the inner side (pin portion P side) in the plate thickness direction.
- the bending rigidity of the arm portion A depends on the arm portion shape of each throw.
- the weight portion W hardly contributes to the bending rigidity.
- the displacement u in the combustion pressure load direction at the axial center of the pin portion P is proportional to the load F of the combustion pressure applied to the pin portion P, as shown by the following equation (1). It is inversely proportional. u ⁇ F / (bending stiffness) ... (1)
- FIG. 3 is a schematic view for explaining the evaluation method of the torsional rigidity of the arm part, and FIG. 3 (a) shows a side view of one throw and FIG. 3 (b) shows its one throw.
- the front view in the axial direction view of is shown. Since the crankshaft rotates about the journal portion J, as shown in FIG. 3, a twisting torque T is generated. Therefore, it is necessary to increase the torsional rigidity of the arm portion A. This is to ensure smooth rotation without causing resonance with respect to torsional vibration of the crankshaft.
- the torsional rigidity of the arm portion A depends on the shape of the arm portion of each throw.
- the weight portion W hardly contributes to the torsional rigidity.
- the twist angle ⁇ of the journal portion J is proportional to the twisting torque T and inversely proportional to the twisting rigidity. ⁇ ⁇ T / (torsion stiffness) ... (2)
- crankshaft of the present invention 2-1.
- the weight portion hardly contributes to the bending rigidity and the torsional rigidity. So, in this embodiment, the arm part shape which is lightweight and simultaneously improves bending rigidity and torsional rigidity is presented.
- FIG. 4 is a view showing a typical example in which the arm portion is regarded as a simple disk from the viewpoint of material rigidity in terms of torsional rigidity.
- Fig. 4 (a) shows a rectangular cross-sectional disk
- Fig. 4 (b) shows a convex cross-sectional disk
- Fig. 4 (c) shows a concave cross-sectional disk.
- the respective weights of the rectangular cross-sectional disk shown in FIG. 4 (a), the convex cross-sectional disk shown in FIG. 4 (b), and the concave cross-sectional disk shown in FIG. It is considered identical. That is, although these discs differ in cross-sectional shape from a rectangle, a convex type, and a concave type, the volumes of these discs are the same.
- the cross-sectional shape of the rectangular cross-sectional disk shown in FIG. 4A is rectangular, the thickness is H 0 , and the diameter is B 0 .
- the cross-sectional shape of the convex cross-sectional disk shown in FIG. 4B is a convex shape in which the central portion protrudes more than the outer peripheral portion, and the diameter of the outermost periphery is B 0 .
- the central portion has a thickness of H 2 and a diameter B 2 for the protruding portion, and the outer peripheral portion has a thickness of H 1 .
- the cross-sectional shape of the concave section disc shown in FIG. 4 (c) the central portion is a concave recessed from the outer peripheral portion, the outermost diameter of B 0. Its central portion has a thickness of depth H 3 of the recess in the H 1, the diameter of the recess is B 3.
- pole secondary moment of each of the three types of disks is represented by the following equations (7) to (9) in consideration of the thickness.
- Pole second moment of rectangular cross section disc: J (A) ( ⁇ / 32) ⁇ H 1 ⁇ B 0 4 (7)
- each dimensional parameter is set as follows.
- B 0 100 mm
- H 0 20 mm
- H 1 10 mm
- the torsional rigidity increases in the order of the convex cross-sectional disc, the rectangular cross-sectional disc, and the concave cross-sectional disc, and it can be said that the concave cross-sectional disc is the most preferable shape.
- FIG. 5 is a view showing a typical example in the case where the cross-sectional shape of the arm portion is simplified from the viewpoint of material mechanical bending stiffness and the arm portion is regarded as a simple beam.
- 5 (a) shows a rectangular cross-section beam
- FIG. 5 (b) shows a convex cross-section beam
- FIG. 5 (c) shows a concave cross-section beam.
- Each weight of the rectangular cross section beam shown in FIG. 5 (a), the convex cross section beam shown in FIG. 5 (b), and the concave cross section beam shown in FIG. 5 (c) is the same in consideration of maintaining the weight reduction. . That is, although these beams differ in cross-sectional shape from a rectangle, a convex type, and a concave type, the cross-sectional areas of these beams are the same.
- the cross-sectional shape of the rectangular cross-section beam shown in FIG. 5A is rectangular, and the thickness is H 0 and the width is B 3 .
- Cross-sectional shape of the convex section beam shown in FIG. 5 (b), the central portion is a convex protruding than both side portions, the total width is B 3.
- the central portion has a thickness of H 2 and a width of B 2 , and both side portions each have a thickness of H 1 and a width of B 1/2 .
- This equation (21) is a conclusion theoretically derived from material dynamics. Qualitatively speaking, this conclusion is based on material mechanics considerations that the moment of inertia of the cross section is higher in the cross sectional shape where many members are placed at a distance from the neutral plane of bending. Understandable.
- each dimension parameter is set as follows.
- B 3 100mm
- H 0 20mm
- H 1 10mm
- H 2 30mm.
- E 1 12.5 mm
- E 2 17.5 mm
- H 3 7.5 mm.
- the cross-sectional secondary moment I (E) of the convex cross-sectional beam is determined from the above equation (19) as shown by the following equation (23).
- I (E) 2.04 x 10 5 ... (23)
- the cross-sectional secondary moment I (F) of the concave cross-section beam is obtained from the above equation (20) as shown by the following equation (24).
- I (F) 2.04 x 10 5 ... (24)
- the convex cross-section beam and the concave cross-section beam have the same bending rigidity with respect to the bending load.
- a convex cross-section beam or a concave cross-section beam in which a part of the arm portion is thickened has a higher bending rigidity and a preferable shape than a rectangular cross-section beam.
- FIG. 6 is a diagram summarizing the magnitude relation between sectional second moment and pole second moment directly related to bending rigidity and torsional rigidity according to the sectional shape.
- the thickness of the arm portion may be increased as a common means to efficiently improve both the bending rigidity and the torsional rigidity.
- the bending rigidity is enhanced, while when the cross-sectional shape is concave, the torsional rigidity is enhanced. From this, by combining these cross sectional shapes, both bending rigidity and torsional rigidity are improved.
- the crankshaft according to the present embodiment in the surface on the pin portion side of the arm portion, the recess is formed along the edge on the inner side of each edge along the contour of the surface It is a thing. Thereby, the outer edge of the recess of the arm portion is thickened, and the inner side of the edge is thinned by the recess. Furthermore, the inside of the recess is thickened. Therefore, the crankshaft according to the present embodiment can realize weight reduction and improvement in torsional rigidity and bending rigidity.
- FIG. 7 is a view schematically showing an example of an arm portion shape in the crankshaft of the first embodiment.
- 7 (a) shows a front view in an axial view from the pin portion side
- FIG. 7 (b) shows an AA sectional view
- FIG. 7 (c) shows a BB sectional view
- 7 (d) shows a CC sectional view
- FIG. 7 (e) shows a DD sectional view.
- the cross section AA in FIG. 7B is a cross section on the arm center line Ac.
- FIG. 7C is a cross-sectional view taken along line B-B of FIG.
- the CC cross section in FIG. 7 (d) is a cross section parallel to the BB cross section and closer to the pin portion than the rotation center of the crankshaft
- the DD cross section in FIG. 7 (e) is a BB cross section. Parallel to the weight section with respect to the rotational center of the crankshaft.
- the recess 10 is formed on the surface on the pin portion P side symmetrically with respect to the arm portion center line Ac.
- the arm portion A has edges 11 on both sides along the contour of the surface on the pin portion P side.
- a recess 10 is formed along each edge 11 inside each edge 11.
- the edge portions 11 on both sides of the arm portion A are thickened, and the inner side of the edge portions 11 is thinned by the recess 10.
- the center part inside the recessed part 10 is thickened.
- FIG. 8 is a view schematically showing an example of an arm portion shape in the crankshaft of the second embodiment.
- 8 (a) shows a front view in an axial view from the pin portion side
- FIG. 8 (b) shows an EE sectional view
- FIG. 8 (c) shows an FF sectional view
- 8 (d) shows a GG sectional view
- E-E cross section, F-F cross section, G-G cross section, and HH cross section of FIG. 8 are positions of the A-A cross section, the B-B cross section, the C-C cross section, and the D-D cross section of FIG. Corresponds to
- the arm portion A of the second embodiment shown in FIG. 8 is based on the configuration of the arm portion A of the first embodiment shown in FIG. 7, and a part of the configuration is modified.
- the recess 10 formed on the surface of the arm portion A on the side of the pin portion P extends to the arm portion center line Ac.
- the recess 10 is connected at the rotational center of the crankshaft, that is, at the position of the axial center Jc of the journal portion J.
- the edge portions 11 on both sides of the arm portion A are thickened, and the inner side of the edge portions 11 is thinned by the recess 10. Furthermore, the center part inside the recessed part 10 is thickened. Further, in the second embodiment, as compared with the first embodiment described above, since the recesses 10 on both sides of the arm portion A are connected, the area of the recess 10 is wider. Therefore, in the arm portion A of the second embodiment, the weight reduction of the crankshaft and the improvement of the torsional rigidity and the bending rigidity can be realized as in the first embodiment. In particular, the shape of the arm portion A of the second embodiment is effective in reducing the weight of the entire crankshaft.
- FIG. 9 is a view schematically showing an example of an arm portion shape in the crankshaft of the third embodiment.
- 9 (a) shows a front view in an axial view from the pin portion side
- FIG. 9 (b) shows an II cross-sectional view
- FIG. 9 (c) shows a JJ cross-sectional view
- 9 (d) shows a K-K cross-sectional view
- FIG. 9 (e) shows an L-L cross-sectional view.
- the positions of the II cross section, the JJ cross section, the KK cross section, and the L-L cross section in FIG. 9 are the positions of the AA cross section, the BB cross section, the CC cross section, and the DD cross section in FIG. Corresponds to
- the arm portion A of the third embodiment shown in FIG. 9 is a modification of a part of the configuration of the arm portion A of the first embodiment shown in FIG.
- the recess 10 formed on the surface of the arm portion A on the side of the pin portion P is connected at a position closer to the pin portion P than the rotational center of the crankshaft.
- the edge portions 11 on both sides of the arm portion A are thickened, and the inner side of the edge portion 11 is thinned by the recess 10. Furthermore, the center part inside the recessed part 10 is thickened. In addition to this, the area of the recess 10 is wider than in the first embodiment. For this reason, the arm part A of 3rd Embodiment has an effect similar to said 2nd Embodiment.
- FIG. 10 is a view schematically showing an example of an arm portion shape in the crankshaft of the fourth embodiment.
- 10 (a) shows a front view in an axial view from the pin portion side
- FIG. 10 (b) shows an MM cross section
- FIG. 10 (c) shows an MN cross section
- 10 (d) shows an OO cross sectional view
- FIG. 10 (e) shows a PP cross sectional view.
- the arm portion A of the fourth embodiment shown in FIG. 10 is a modification of a part of the configuration of the arm portion A of the first embodiment shown in FIG.
- the recess 10 formed on the surface of the arm portion A on the side of the pin portion P is connected at a position closer to the weight portion W than the rotational center of the crankshaft.
- the recess 10 shown in FIG. 10 leads along the contour of the journal portion J.
- the edge portions 11 on both sides of the arm portion A are thickened, and the inside of the edge portion 11 is thinned by the recess 10. Furthermore, the center part inside the recessed part 10 is thickened. In addition to this, the area of the recess 10 is wider than in the first embodiment. For this reason, the arm part A of 4th Embodiment has an effect similar to said 2nd, 3rd embodiment.
- the crankshaft of this embodiment is intended for a crankshaft mounted on any reciprocating engine. That is, the number of cylinders of the engine may be any of two cylinders, three cylinders, four cylinders, six cylinders, eight cylinders, ten cylinders, or more.
- the arrangement of the engine cylinders may also be in series arrangement, V-shaped arrangement, opposed arrangement, etc.
- the fuel for the engine may also be 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.
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Abstract
Description
回転中心軸となるジャーナル部と、このジャーナル部に対して偏心したピン部と、前記ジャーナル部と前記ピン部をつなぐクランクアーム部と、前記クランクアーム部と一体のカウンターウエイト部と、を備える。前記クランク軸は、レシプロエンジンに搭載される。
前記クランクアーム部の前記ピン部側の表面において、この表面の輪郭に沿った両側それぞれの縁部の内側にこの縁部に沿って凹部が形成されている。
1-1.アーム部の曲げ剛性
図2は、アーム部の曲げ剛性の評価法を説明するための模式図である。図2に示すように、クランク軸の各スローについて、シリンダ内での爆発による燃焼圧の荷重Fは、コンロッドを経由してピン部Pに負荷される。このとき、各スローは両端のジャーナル部Jが軸受けによって支持されるので、荷重Fはピン部Pからアーム部Aを介してジャーナル軸受けに伝わる。これにより、アーム部Aは3点曲げの荷重負荷状態となり、アーム部Aに曲げモーメントMが作用する。これに伴って、アーム部Aには、板厚方向の外側(ジャーナル部J側)で圧縮応力が発生し、板厚方向の内側(ピン部P側)では引張応力が発生する。
u ∝ F/(曲げ剛性) …(1)
図3は、アーム部のねじり剛性の評価法を説明するための模式図であり、図3(a)は1スローの側面図を示し、図3(b)はその1スローの軸方向視での正面図を示す。クランク軸はジャーナル部Jを中心に回転運動をしているので、図3に示すように、ねじりトルクTが発生する。そこで、アーム部Aのねじり剛性を高めることが必要である。クランク軸のねじり振動に対し、共振を起こすことなくスムーズな回転を確保するためである。
γ ∝ T/(ねじり剛性) …(2)
2-1.アーム部剛性向上のための考え方
上述のとおり、ウエイト部は曲げ剛性とねじり剛性にほとんど寄与しない。そこで、本実施形態では、軽量で曲げ剛性とねじり剛性が同時に向上するアーム部形状を提示する。
ここでは、材料力学の理論に基づいて、ねじり剛性を向上させるための典型的な形状を検討する。前記図3に示すアーム部Aについて、軽量化を維持しつつねじり剛性を向上させるには、極2次モーメントを大きくすることが有効である。
極2次モーメント:J=(π/32)×d4 …(4)
ねじれ角:γ=T×L/(G×J) …(5)
式(3)~式(5)中、Lは軸方向長さ、Gは横弾性率、dは丸棒の半径、Tはねじりトルクである。
(π/4)×B0×B0×H0=(π/4)×(B0×B0×H1+B2×B2×H2)=(π/4)×{B0×B0×(H1+H3)-B3×B3×H3)} …(6)
矩形断面円板の極2次モーメント:
J(A)=(π/32)×H1×B0 4 …(7)
J(B)=(π/32)×(H1×B0 4+H2×B2 4) …(8)
J(C)=(π/32)×{(H1+H3)×B0 4-H3×B3 4} …(9)
J(B) < J(A) < J(C) …(10)
B0=100mm、H0=20mm、H1=10mm、H2=H3=20mm、B2=B3=100/√2=70.71mm。
J(A)=1.96×108 …(11)
J(B)=1.47×108 …(12)
J(C)=2.45×108 …(13)
ここでは、材料力学の理論に基づいて、曲げ剛性を向上させるための典型的な形状を検討する。前記図2に示すアーム部Aについて、軽量化を維持しつつ曲げに対する曲げ剛性を向上させるには、断面形状の曲げ断面2次モーメントを大きくすることが効率的である。
断面2次モーメント:I=(1/12)×b×h3 …(15)
たわみ変位:u=k(M/(E×I)) …(16)
式(14)~式(16)中、bは幅、hは厚み、Eは縦弾性率、Mは曲げモーメント、kは形状係数である。
B3×H0=(H2×B2+B1×H1)=(H2×B2+B1×H1) …(17)
矩形断面梁の断面2次モーメント:
I(D)=(1/12)×B3×H0 3 …(18)
I(E)=1/3×(B3×E2 3-B1×H3 3 +B2×E1 3) …(19)
式(19)中、
E2は「(B2×H2 2+B1×H1 2)/{2×(B2×H2+B1×H1)}」、
E1は「H2-E2」、
H3は「E2-H1」である。
I(F)=1/3×(B3×E2 3-B1×H3 3 +B2×E1 3) …(20)
式(20)中、
E2は「(B2×H2 2+B1×H1 2)/{2×(B2×H2+B1×H1)}」、
E1は「H2-E2」、
H3は「E2-H1」である。
I(D) < I(E) = I(F) …(21)
B1=B2=50mm、B3=100mm、H0=20mm、H1=10mm、H2=30mm。このとき、E1=12.5mm、E2=17.5mm、H3=7.5mmとなる。
I(D)=6.67×104 …(22)
I(E)=2.04×105 …(23)
I(F)=2.04×105 …(24)
図6は、曲げ剛性とねじり剛性に直接関連する断面2次モーメント及び極2次モーメントについて、断面形状に応じて大小関係をまとめた図である。図6では、前記図4及び図5に示す矩形断面、凸型断面及び凹型断面の断面形状ごとに、極2次モーメント及び断面2次モーメントを、矩形断面を基準「1」とした比率で表示する。
上述したように、曲げ剛性とねじり剛性を共に向上させるには、アーム部の断面形状を凸型と凹型を組み合わせた形状に設計することが有効である。すなわち、アーム部の輪郭に沿った両側の縁部を厚肉化し、この縁部の内側を薄肉化する。更にその薄肉化された部分の内側である中央部(アーム部中心線上でジャーナル部寄りの部分)を厚肉化する。アーム部のねじり中心から遠い縁部を厚肉化すると同時に、その内側を薄肉化することにより、軽量化を実現しつつ、ねじり剛性を高く確保できる。アーム部の縁部の厚肉化は、曲げ剛性の確保に寄与する。加えて、曲げ剛性の確保には、アーム部の中央部の厚肉化が寄与する。
[第1実施形態]
図7は、第1実施形態のクランク軸におけるアーム部形状の一例を模式的に示す図である。図7(a)はピン部側からの軸方向視での正面図を示し、図7(b)はA-A断面図を示し、図7(c)はB-B断面図を示し、図7(d)はC-C断面図を示し、図7(e)はD-D断面図を示す。図7(b)のA-A断面は、アーム部中心線Ac上の断面である。図7(c)のB-B断面図は、アーム部中心線Acに直角でクランク軸の回転中心(ジャーナル部の軸心Jc)を通る断面である。図7(d)のC-C断面は、B-B断面と平行でクランク軸の回転中心よりもピン部寄りの断面であり、図7(e)のD-D断面は、B-B断面と平行でクランク軸の回転中心よりもウエイト部寄りの断面である。
図8は、第2実施形態のクランク軸におけるアーム部形状の一例を模式的に示す図である。図8(a)はピン部側からの軸方向視での正面図を示し、図8(b)はE-E断面図を示し、図8(c)はF-F断面図を示し、図8(d)はG-G断面図を示し、図8(e)はH-H断面図を示す。図8のE-E断面、F-F断面、G-G断面、H-H断面は、それぞれ前記図7のA-A断面、B-B断面、C-C断面、D-D断面の位置に対応する。
図9は、第3実施形態のクランク軸におけるアーム部形状の一例を模式的に示す図である。図9(a)はピン部側からの軸方向視での正面図を示し、図9(b)はI-I断面図を示し、図9(c)はJ-J断面図を示し、図9(d)はK-K断面図を示し、図9(e)はL-L断面図を示す。図9のI-I断面、J-J断面、K-K断面、L-L断面は、それぞれ前記図7のA-A断面、B-B断面、C-C断面、D-D断面の位置に対応する。
図10は、第4実施形態のクランク軸におけるアーム部形状の一例を模式的に示す図である。図10(a)はピン部側からの軸方向視での正面図を示し、図10(b)はM-M断面図を示し、図10(c)はN-N断面図を示し、図10(d)はO-O断面図を示し、図10(e)はP-P断面図を示す。図10のM-M断面、N-N断面、O-O断面、P-P断面は、それぞれ前記図7のA-A断面、B-B断面、C-C断面、D-D断面の位置に対応する。
J、J1~J5:ジャーナル部、 Jc:ジャーナル部の軸心、
P、P1~P4:ピン部、 Pc:ピン部の軸心、
Fr:フロント部、 Fl:フランジ部、
A、A1~A8:クランクアーム部、 Ac:アーム部中心線、
W、W1~W8:カウンターウエイト部、
2:ダンパプーリ、 3:フライホイール、
10:凹部、 11:縁部
Claims (5)
- 回転中心軸となるジャーナル部と、このジャーナル部に対して偏心したピン部と、前記ジャーナル部と前記ピン部をつなぐクランクアーム部と、前記クランクアーム部と一体のカウンターウエイト部と、を備え、レシプロエンジンに搭載されるクランク軸であって、
前記クランクアーム部の前記ピン部側の表面において、この表面の輪郭に沿った両側それぞれの縁部の内側にこの縁部に沿って凹部が形成されている、レシプロエンジンのクランク軸。 - 請求項1に記載のレシプロエンジンのクランク軸であって、
前記凹部は、クランク軸の回転中心の位置でつながる、レシプロエンジンのクランク軸。 - 請求項1に記載のレシプロエンジンのクランク軸であって、
前記凹部は、クランク軸の回転中心よりも前記ピン部寄りの位置でつながる、レシプロエンジンのクランク軸。 - 請求項1に記載のレシプロエンジンのクランク軸であって、
前記凹部は、クランク軸の回転中心よりも前記カウンターウエイト部寄りの位置で前記ジャーナル部の輪郭に沿ってつながる、レシプロエンジンのクランク軸。 - 請求項1~4のいずれかに記載のレシプロエンジンのクランク軸であって、
前記凹部は、前記ジャーナル部の軸心と前記ピン部の軸心とを結ぶ直線に対して対称である、レシプロエンジンのクランク軸。
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BR112017002187A BR112017002187A2 (pt) | 2014-08-07 | 2015-08-06 | virabrequim para motores alternativos |
US15/501,013 US10330142B2 (en) | 2014-08-07 | 2015-08-06 | Crankshaft for reciprocating engine |
CN201580042108.XA CN106574650B (zh) | 2014-08-07 | 2015-08-06 | 往复式发动机的曲轴 |
EP15829623.6A EP3179116A4 (en) | 2014-08-07 | 2015-08-06 | Crankshaft of reciprocating engine |
MX2017001685A MX2017001685A (es) | 2014-08-07 | 2015-08-06 | Cigüeñal para motor reciprocante. |
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CN106574650A (zh) | 2017-04-19 |
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US10330142B2 (en) | 2019-06-25 |
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