JP2704723B2 - Crankshaft - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Object of the Invention (1) Industrial Field of the Invention The present invention relates to a crankshaft used for a reciprocating internal combustion engine or the like. (2) Prior Art It is conventionally known to divide the above-mentioned crankshaft into several elements by means of a divided joining surface crossing the axis thereof and to weld these divided joining surfaces to each other. In this case, if the divided joint surface is provided on the journal portion or crank pin portion where relatively high processing accuracy is required and a large load is applied, it is necessary to sufficiently perform post-processing after the welding operation of the divided joint surfaces. Therefore, the work is troublesome, and the load on the welded portion is large, which is disadvantageous in terms of strength. Such a problem can be solved, for example, by providing a split joint surface of a crankshaft in a crank arm as disclosed in Japanese Utility Model Laid-Open No. Sho 59-181321. (3) Problems to be Solved by the Invention However, in the above-described proposal, the crankshaft axis is orthogonal to the split joint surface of the crank arm so that the counterweight extending to the crank arm is also bisected. The welding area is long and the joint is susceptible to thermal strain, which reduces the welding accuracy (for example, it is difficult to ensure linearity), or increases the number of welding steps and time There are problems such as poor work efficiency.In addition, since the crank arm half and the journal or crank pin are separately manufactured and integrally connected by retrofitting, there is a disadvantage in strength and accuracy. Therefore, there is a problem that the assembling work is troublesome. The present invention has been proposed in view of the above, and an object of the present invention is to provide a crankshaft that can solve the above-described problems of the conventional one. B. Configuration of the Invention (1) Means for Solving the Problems According to the present invention, in order to achieve the above object, at least a part of a crank arm portion is divided into a first and a second crank arm half. And a first and second crank arm halves welded to each other on the divided joint surface, wherein the first crank arm half and the first crank arm half are connected to each other. A seamless first crankshaft element including a crankpin portion connected to a side portion, the second crank arm half, a journal portion connected to a side portion of the second crank arm half, and the second crank arm A seamless second crankshaft element including a counterweight portion extending from the outer periphery of the half-side journal portion side to the opposite side to the crankpin portion; The crank axis extends so as to extend over the outer periphery of the end portion of the rank arm portion on the crank pin side and the outer periphery of the end portion on the journal portion, and further away from the counterweight portion as approaching the outer periphery of the end portion on the journal portion side. Formed diagonally across. (2) Operation According to the above configuration, the split joint surface for splitting the crankshaft into the plurality of crankshaft elements is provided on the crank arm portion, and includes the first crank arm half and the crank pin portion connected to the side portion thereof. A second crankshaft element including a first crankshaft element or a second crank arm half and a journal portion connected to a side portion thereof and a counterweight portion connected to an end of the second crank arm half portion on the journal portion side is provided. Since each is manufactured as a seamless single part, it is not only advantageous in terms of strength and accuracy compared to a structure in which the crank arm half, the crank pin portion, the journal portion, etc. are individually manufactured and then joined later. Also, the number of assembly steps is reduced. In particular, the split joint surface extends over the outer periphery of the end of the crank arm portion on the side of the crank pin and the outer periphery of the end of the crank portion, and furthermore, as it approaches the outer periphery of the end of the crank portion, the counterweight becomes smaller. It is formed obliquely across the crank axis so as to be farther from the part, so that the divided joint surface (and thus the welded part) can be prevented from becoming too long to divide the counterweight part into two parts, and the number of welding steps and time can be reduced. It is possible to reduce as much as possible, and it is also possible to suppress as much as possible a decrease in welding accuracy due to the influence of thermal strain caused by welding. Further, since the outer peripheral edge of the split joining surface goes around the outer peripheral surface instead of the side surface of the crank arm portion and is arranged to escape from the counter weight portion, the counter weight portion is not disturbed. The outer peripheral portion of the divided joining surface can be easily and accurately welded over the entire periphery. (3) Embodiment Hereinafter, an embodiment in which the present invention is applied to a crankshaft for an internal combustion engine will be described with reference to the drawings. In FIGS. 1 and 2, a main part of a steel crankshaft 1 is rotatable to a crankcase (not shown). Journal part 2 supported by a shaft and a crankpin part 3 to which a connecting rod (not shown) is rotatably connected.
And a crank arm part 4 connecting the two. Each journal part 2 and crank pin part 3
Are formed with hollow holes 2a and 3a for lightening, and each of the crank arms 4 is provided with a divided joining surface S crossing the same. Crankshaft 1 Thus is divided into a plurality of crankshaft elements P ₁ to P ₉ by the dividing joint surface S, by their elements P ₁ to P ₉ are cast or forged and machined, fabricated individually as seamless Is done. Each of the crankshaft elements P _1-
P ₉ to each other is phase Tonariru those are bound to each other by coupling structures, such as described below. As shown in FIGS. 3 and 4, each of the crank arm portions 4 includes a first crank arm half 6 in which the crank pin portion 3 is continuously connected to a side portion and a journal portion 2 by the divided joint surface S. It is divided into a second crank arm half 5 continuously connected to the side portion, and the outer periphery of the end portion of the second crank arm half 5 on the journal portion 1 side is opposite to the crank pin portion 3. A counterweight portion W extending to the side extends seamlessly, and an auxiliary weight 9 is integrally provided at one end of the counterweight portion W to protrude therefrom. The end surfaces 6a, 5a of the first and second crank arm halves 6, 5 which abut against each other (therefore, the split joint surface S) are formed by the outer periphery of the end of the crank arm portion 4 on the side of the crank pin 3 and the journal. It is formed in a circular surface obliquely crossing the crank axis so as to extend over the outer periphery of the end on the side of the portion 2 and further away from the counterweight W as it approaches the outer periphery of the end on the side of the journal 2. In addition, the end faces 6a, 5a of the two crank arm halves 6, 5 are fitted with each other so as to be able to be inserted and removed in the axial direction of the crankshaft. That is, the end face 5a of the second crank arm halves 5 semicircular recesses 5b ₁ in its lower half portion, also semi-circular protrusions on half portion thereon 5
b ₂ are formed respectively, the end face of the semi-circular recess 5b ₁ of the bottom surface and the semi-circular protrusions 5b ₂ are continuous with each other are formed on the same plane perpendicular to the crank axis l. Wherein the end face of the semi-circular protrusions 5b ₂ of the crank arm portion 4 lightening holes 4a
But also hollow hole 2a of the journal portion 2 on the bottom surface of the semi-circular recess 5b ₁ are opened, respectively. The end surface 6a of the first crank arm half 6 has a semicircular projection 6b ₁ on the lower half of the end surface 6a which fits into the semicircular recess 5b ₁ of the second crank arm half 5.
But also the semi-circular recess 6b ₂ which fits into the semicircular convex portion 5b ₂ are formed respectively, end faces and semicircular recesses of semicircular protrusions 6b ₁ of the second crank arm halves 5 half section thereon bottom of 6b ₂ be formed on the same plane perpendicular to the crank axis l are continuous with each other. Wherein the bottom surface of the semi-circular recess 6b ₂ is opened hollow hole 3a of the crank pin 3 and the cylindrical fitted into the hollow hole 2a semicircular protrusions 6b ₁ of the end face journal portion 23 small The protrusion 7 is formed. Thus, the first and second crank arm halves 6 and 5 are connected to each other by a suitable welding means such as a laser welding means or an electronic welding means around the periphery of the crank arm part 4 in the fitting state. It is welded over the entire circumference by beam welding means. Thus, the crankshaft 1 includes a plurality of crankshaft elements P ₁ to
First crankshaft elements P ₂ , P are provided on the crank arm portion 4 with a split joint surface S for splitting the crankshaft P ₉ , and include the first crank arm half 6 and the crank pin portion 3 connected to the side thereof.
₄ , P ₆ , P ₈ , a second crank arm half 5, a journal portion 2 connected to a side thereof, and a counterweight portion W connected to an end of the second crank arm half 5 on the journal side. second crank shaft element _{P 1, P 3, P 5} , P 7, P 9 is manufactured as each seam no single part. Therefore, the crank arm halves 6,5, the crank pin 3 and the journal 2
This is advantageous not only in strength and accuracy but also in the number of assembling steps, as compared with a structure in which components are individually manufactured and then joined later. In FIGS. 1 and 2, reference numeral 10 denotes an oil passage for communicating the hollow holes 2a and 3a to the outside, and 11 denotes an oil passage for communicating between the hollow holes 2a and 3a. FIG. 5 is a graph showing an example of the axial stress distribution of the crankshaft 1 during the operation of the crankshaft. Points A to G on the horizontal axis show the axial positions of the corresponding crankshaft cross-sections, respectively. I have. According to this graph, the generated stress of the crank arm portion (corresponding to the point D) is significantly smaller than that of the crank pin portion (corresponding to the points A to C) and that of the journal portion (corresponding to the points E to G). Is clear, and thus the crank arm 4
Even if the divided joint surface S is provided, the load on the welded portion on the divided joint surface S can be relatively small. In particular, the split joint surface S of the crankshaft 1 extends over the outer periphery of the end of the crank arm portion 4 on the side of the crank pin 3 and the outer periphery of the end of the crank portion 2 on the side of the journal 2, and moreover, on the side of the journal 2. Since it is formed obliquely across the crankshaft so as to become farther from the counterweight portion W as it approaches the outer periphery of the end portion, the divided joint surface S (therefore, the welded portion) is so long that it divides the counterweight portion W into two parts. In addition to reducing welding man-hours and time as much as possible, work efficiency can be increased, as well as reducing welding accuracy due to the effects of thermal strain due to welding. Securing is also easy. Further, since the outer peripheral edge of the split joining surface S is arranged not to be on the side surface of the crank arm portion 4 but around the outer peripheral surface and to escape from the counterweight portion W, the counterweight portion W It is possible to easily and accurately weld the outer peripheral portion of the divided joining surface S over the entire periphery without being disturbed by the welding. In the above embodiment, the shape of the divided joint surface S in the crank arm portion 4 is circular. However, in the present invention, the shape of the divided joint surface S is formed into, for example, an elliptical shape as shown in FIG. Or a rectangle. Further, in the above-described embodiment, all the crank arms 4
In the present invention, it is a matter of course that the divided joint surface S may be provided only in some of the crank arms 4 as shown in FIG. 7, for example. C. Effects of the Invention As described above, according to the present invention, a split joint surface for splitting a crankshaft into a plurality of crankshaft elements is provided in a crank arm portion, and the first crank arm half and a crank connected to its side portion are provided. A first crankshaft element including a pin portion;
The second crankshaft element including the crank arm half, the journal part connected to the side part thereof, and the counterweight part connected to the end part on the journal part side of the second crank arm half is manufactured as a seamless single part. Therefore, not only is it advantageous in terms of strength and accuracy, but also the number of assembling steps is reduced, which contributes to cost reduction and improvement in assembling work efficiency. In particular, the split joint surface extends over the outer periphery of the end of the crank arm portion on the side of the crank pin and the outer periphery of the end of the crank portion. Since it is formed obliquely across the crank axis so as to be farther away from the part, it is possible to avoid that the divided joint surface (and thus the welded part) becomes too long to divide the counterweight part into two parts. Not only can the work efficiency be reduced as much as possible, but also the welding accuracy can be reduced by the influence of thermal distortion due to welding, and the linearity can be easily ensured by minimizing the welding accuracy. Further, since the outer peripheral edge of the split joint surface is arranged so as to go around the outer peripheral surface instead of the side surface of the crank arm portion and escape from the counterweight portion, the counterweight portion is disturbed. In addition, the outer peripheral portion of the divided joining surface can be easily and accurately welded over the entire periphery.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows an embodiment of the present invention. FIG. 1 is an overall front view of a crankshaft, FIG.
FIG. 3 is an exploded view of a main part of the crankshaft, and FIG. 4 is FIG.
IV view, FIG. 5 is a graph showing the axial stress distribution of the crankshaft, FIG. 6 shows a modification of the crank arm portion,
FIG. 7 is a view similar to FIG. 4, and FIG. 7 shows a modification of the crankshaft.
FIG. 3 is an overall vertical sectional view similar to FIG. 2. P ₂ , P ₄ , P ₆ , P ₈ … First crankshaft element, P ₁ , P ₃ , P ₅ , P ₇ , P ₉
... Second crankshaft element, S.... Split joint surface, W ..... Counterweight part,..., Crankshaft,. ... second crank arm half, 6 ... first crank arm half

   ────────────────────────────────────────────────── ─── Continuation of front page    (56) References JP-A-64-3312 (JP, A)                 Actual opening sho 59-181321 (JP, U)                 Tokiko 49-38217 (JP, B2)

Claims (1)

(57) [Claims] At least a part of the crank arm portion (4) is provided with a divided joint surface (S) for dividing the crank arm portion (4) into first and second crank arm halves (6, 5). In a crankshaft formed by welding and joining a first and a second crank arm half (6, 5) to each other, a first crank arm half (6) and a side portion of the first crank arm half (6) are provided. A series of crank pins (3)
And the first crankshaft element (P ₂ , P ₄ , P ₆ , P
₈ ), the second crank arm half (5), and a journal portion (2) connected to a side of the second crank arm half (5).
And a counterweight portion (W) extending from the outer periphery of the end of the second crank arm half (5) on the journal (2) side to the opposite side to the crankpin portion (3). A crankshaft element (P ₁ , P ₃ , P ₅ , P ₇ , P ₉ ), and the split joint surface (S) is an end of the crank arm (4) on the side of the crank pin (3). The crank axis extends obliquely so as to extend over the outer periphery of the portion and the outer periphery of the end portion on the journal portion (2) side, and further away from the counterweight portion (W) as it approaches the outer periphery of the end portion on the journal portion (2) side. A crankshaft characterized in that it is formed transversely to the crankshaft.