JP2008175390A - Crankshaft - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve rigidity and wear resistance of a crankshaft. <P>SOLUTION: The crankshaft used for an internal combustion engine or a reciprocating air compressor and comprising a crank journal, a crank pin and a crank arm which is a connection part between the crank journal and the crank pin, is provided with a reinforcing groove part formed at the outer peripheral edges of the crank pin and crank journal; an outer diameter member formed of metal different from the crank pin and the crank journal and cast to be fitted and fusion-joined to the reinforcing groove part; and a stepped groove part formed inside the reinforcing groove part. The outer diameter member is formed of nodular graphite cast iron. The crankshaft has an effect of maintaining product safety even under use for a long time and being usable as an excellent product by joining particularly the outer diameter member by a fitting structure. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a hollow crankshaft that converts a reciprocating motion into a rotational motion. More specifically, a reinforcing groove is formed on the outer peripheral surface of the crankpin and the crank journal, and the rigidity different from the crankpin and the crank journal is formed in the reinforcing groove. The present invention relates to a crankshaft cast so as to fit and melt-bond metals.

  The crankshaft according to the present invention is greatly increased in rigidity against bending load, shear load and torsional load due to different rigid metals, and accordingly, the reliability of the crankshaft parts is improved, and for the joining provided in the mold. The cast iron (cast steel and ductile cast iron) structure of the joint becomes dense due to the rapid quenching structure of the metal, and by removing defects on the casting surface, it is superior in productivity compared to existing forged crankshafts and at low cost It is a very useful invention that has various functional effects such as being able to be made.

  As is well known, a conventional ordinary crankshaft is mainly supported by a main bearing in a crankcase, and a linear motion of a piston obtained by a power stroke of each cylinder is converted into a rotational motion via a connecting rod. It is an important member that conveys the output of. The crankshaft includes a crank journal, a crankpin, and a crank arm that connects the crank journal and the crankpin. The crankshaft is connected to the large end of the connecting rod at the clamp pin, and is supported by the main bearing in the crankcase at the crank journal, and receives the force of the piston through the crankpin and converts it into rotational motion.

  However, the conventional forged die crankshaft requires a forging process in several stages as necessary after ingot casting, and the process becomes complicated. There is a drawback in that the productivity is low due to the difficulty in processing, and the cost is also increased.

  In addition, there is a method to manufacture a crankshaft in an integral type using spheroidal graphite cast iron with improved rigidity. However, due to the characteristics of cast iron, it has lower rigidity than forged steel and is less susceptible to impacts. Cast steel and ductile cast iron In both cases, the defect rate of the material was increased due to casting defects formed in the parts of the crank journal and the crankpin, and surface heat treatment for enhancing wear resistance was difficult.

  The present invention has been made in view of the above-described problems, and an object thereof is to improve the rigidity and wear resistance of the crankshaft.

  As a result of repeated research on crankshafts, the present applicant has manufactured a dissimilar metal joint type crankshaft that can improve rigidity while simplifying the manufacturing process by joining outer diameter members to the outer peripheral surface of the crankshaft. The inventors have found that this is possible and have completed the present invention.

  Specifically, the crankshaft according to the present invention is used in an internal combustion engine or a reciprocating air compressor, and includes a crank journal, a crankpin, and a crank arm that is a joint portion between the crank journal and the crankpin. In the crankshaft, the crank pin and the reinforcing groove formed on the outer peripheral edge of the crank journal and the crank pin and the upper crank journal are made of different metals, and are cast so as to fit into the reinforcing groove and melt-bond. An outer diameter member and a stepped groove portion inside the reinforcing groove portion, and the outer diameter member is made of spheroidal graphite cast iron.

  The present invention can improve the rigidity and wear resistance of the crankshaft by forming reinforcing groove portions on the outer periphery of the crankpin and the crank journal, and melt-bonding and casting different metals as outer diameter members in the reinforcing groove portions.

  Further, the present invention has a trapezoidal cross-section formed with an inclined surface having an outer narrow inner width that narrows as the stepped groove portion progresses from the outside to the inside, and the outer diameter member is arranged outside the crankpin. It may be formed to a thickness of 4% to 12% of the diameter.

  Further, the inner corner portion of the outer diameter member may be rounded to prevent cracking.

  According to the present invention, the cost of a crankshaft manufactured by conventional forging is high because the cost of the product increases due to the cost of expensive molds, and it is difficult to produce a variety of products in small quantities, and the production process is complicated. On the other hand, the crankshaft according to the present invention is a crankshaft in which dissimilar metals are joined to the outer peripheral surface, and can be produced in a wide variety and in small quantities. Can be manufactured.

  As described above, the safety of the product is improved by preventing cracking by dissimilar metal fusion bonding, and in particular, since the outer diameter member is joined by the fitting structure, it can be used for a long time depending on the material selection of the member. Even if it is used, the lifetime can be maintained for a long time, and an excellent product can be produced.

  Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a perspective view of the present invention. As shown in FIG. 1, a crankshaft A according to the present invention is connected to a large end portion of a connecting rod and receives the force of a piston to rotate it. A crankpin 1 to be converted, a crank journal 2 that is a portion serving as a central axis of rotational motion in the crankcase, and a crank arm 3 that is a joint portion between the crank journal 2 and the crankpin 1 are provided.

  A reinforced groove portion 4 is formed on the outer periphery of the crankpin 1 and the crank journal 2 of the crankshaft A, and an outer diameter member 40 made of a metal different from the metal material of the crankpin 1 and the crank journal 2 is fitted into the reinforced groove portion 4. They are cast so that they are fused and joined. The crankpin 1 of the crankshaft A is a shaft having a circular cross section connected to the large end of the connecting rod. The crank arm 3 has a main surface formed in an elliptical shape. The outer diameter member 40 formed on the outer peripheral edge portion of the crankpin 1 is formed over the peripheral surface of the crankpin 1, and the main surface and the peripheral edge of the crank arm 3 connected at the end of the crankpin 1. It is stretched to a part.

  FIG. 2 is a front sectional view of the present invention. As shown in FIG. 2, when casting the crankshaft A according to the present invention, an outer diameter member 40 is interposed outside the crankpin 1 and the crank journal 2, and along the central axis inside the crankpin 1. A hollow portion 31 is formed, and a pipe-shaped hollow portion 30 along the central axis of the main shaft is formed inside the crank journal 2 and is cast as a whole.

  At this time, when the outer diameter member 40 is fitted into the reinforced groove portion 4, in order to prevent detachment from the reinforced groove portion 4, a taper that becomes wider toward the central axis at both end faces, that is, A gradient is provided inward. Further, the corner portion of the outer diameter member 40 is rounded before fitting so as not to cause a resinous structure on the molten material side due to the sharp corner portion during casting joining. In order to ensure high-precision joining of the crankshaft A and sufficient rigidity, the thickness of the outer diameter member 40 is suitably about 4% to 12% in proportion to the outer diameters of the crankpin 1 and the crank journal 2. is there.

  The material of the outer diameter member 40 described above is preferably spheroidal graphite cast iron, cast steel, and ash cast iron. Among them, spheroidal graphite cast iron and cast steel are particularly preferable.

  As shown in the enlarged view of the main part of FIG. 2, the outer diameter member 40 is joined to the reinforced groove portion 4 formed on the outer side of the crankshaft A. In order to prevent the outer diameter member 40 from coming off, In the reinforced groove portion 4, an inclined surface is formed from the inside toward the outside corresponding to the taper of the outer diameter member 40, and the inclined portion forms a stepped groove portion 41. That is, the stepped groove portion 41 is formed so as to have an inner and outer inclined surface.

  FIG. 3 is a cut perspective view of the present invention. As shown in FIG. 3, the hollow portions 31 and 30 formed along the respective central axes of the crankpin 1 and the crank journal 2 function as an oil sump. The hollow portion 31 is formed along the central axis of the crankpin 1 and passes through the crank arm 3 connected to both ends of the crankpin 1, and the through holes at both ends are closed by caps. The crankpin 1 and the outer diameter member 40 are formed with a through hole 32 that is communicated with the hollow portion 31 at substantially the center in the central axis direction and supplies oil inside the hollow portion 31 to the surface of the outer diameter member 40. Yes. The hollow portion 30 is formed along the central axis of the crank journal 2, passes through the crank arm 3 connected to the crank journal 2, and the through hole at the end on the crank arm 3 side is closed by a cap. The crank journal 2 is supported by a main bearing via an outer diameter member 40, supplies oil from the main bearing side to the hollow portion 30, and is provided in a direction orthogonal to the central axis at the end of the crank journal 2. A groove 33 is formed to supply oil to the surface of the outer diameter member 40 of the crank journal 2. Further, the crank arm 3 is formed with a through hole 34 that penetrates the central axis of the crank pin 1 from the outer surface and communicates with the central axis of the crank journal 2. The through hole 34 can supply oil supplied to the hollow portion 30 to the hollow portion 31 and supply oil to the entire surface of the crankshaft A.

  As described above, the crankshaft A according to the present invention significantly increases the strength of the crankshaft A by joining the outer peripheral member 40 with high rigidity to the outer peripheral edge portions of the crankpin 1 and the crank journal 2. Hereinafter, the operating state of the present invention will be described.

  In general, the crankshaft A is provided in the crankcase, converts the linear motion of the piston obtained in the power stroke of each cylinder into a rotational motion, and transmits the output of the engine to the outside. In the process, the movement is transmitted to the piston. The crankshaft is required to have the following characteristics. That is, 1) rotating smoothly while maintaining a balance between dynamic and static, 2) particularly high rigidity to rotate at high speed while receiving a large load and impact, and 3) long life. It has excellent wear resistance.

  That is, the crankshaft A in which dissimilar metals are joined to the outer peripheral surface according to the present invention is manufactured by fitting the outer diameter member 40 to the crankpin 1 and the crank journal 2, and thus is manufactured from the cast steel spheroidized cast iron. Compared to a crankshaft, it is superior in rigidity and wear resistance, and can be manufactured at a lower cost than a forged crankshaft.

  Further, in the crankshaft A in which the dissimilar metal is joined to the outer peripheral surface, in addition to the above-described features, the joining metal (outer diameter member 40) provided in the mold functions as cold metal.

  In addition, the crankshaft A according to the present invention can be easily subjected to surface heat treatment of the crankpin and the crank journal as compared with those manufactured entirely from cast steel or spheroidal graphite cast iron.

  Although the present invention has been described in detail with reference to the accompanying drawings, the present invention is not limited to this, and various modifications and changes are possible as long as they are within the scope of the claims. Needless to say.

It is a perspective view of a crankshaft to which the present invention is applied. It is a front sectional view of a crankshaft to which the present invention is applied. It is an incision perspective view of a crankshaft to which the present invention is applied.

Explanation of symbols

A Crankshaft 1 Crankpin 2 Crank journal 3 Crank arm 4 Reinforcing groove 40 Outer diameter member 41 Stepped groove

Claims (4)

In a crankshaft used for an internal combustion engine or a reciprocating air compressor, comprising a crank journal, a crankpin, and a crank arm that is a joint portion of the crank journal and the crankpin.
Reinforcing groove formed on the outer peripheral edge of the crank pin and the crank journal,
An outer diameter member made of a metal different from the crank pin and the upper crank journal, and cast so as to be fitted into the reinforcing groove and melt-bonded;
A stepped groove is provided inside the reinforced groove,
The crankshaft characterized in that the outer diameter member is made of spheroidal graphite cast iron.   The crankshaft according to claim 1, wherein the stepped groove portion has a trapezoidal cross-section in which an inclined surface having an outer width and an inner width is formed.   The crankshaft according to claim 1 or 2, wherein the outer diameter member is formed to have a thickness of 4% to 12% of an outer diameter of the crankpin.   The crankshaft according to claim 3, wherein the inner corner portion of the outer diameter member is rounded.

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