JP3138083U - Crankshaft for automobile engine - Google Patents

Abstract

A lightweight and high-quality assembly-type crankshaft applicable to a multi-cylinder engine is provided.
A crankshaft for an automobile engine in which pins connected to a piston of each cylinder by a connecting rod are rotated by a predetermined angle with respect to a central axis, journals 2K, 2L, 2M, 2N, pins 3K, 3L, 3N, and arms 10A to 10F are separately manufactured and assembled by fixing them by shrinkage.
A connecting portion having a pyramidal surface is extended at both ends of the journal and the pin, and the arm is provided with a pyramid hole in which a balance weight is integrally formed and the connecting portion is fitted. The journal and pin connection portions are symmetrical, and a pyramid hole corresponding to the journal connection portion is formed by rotating a predetermined angle.
[Selection] Figure 1

Description

  The present invention relates to a crankshaft used for an automobile engine, particularly a multi-cylinder engine.

A crankshaft for an automobile engine is a part for changing a reciprocating motion into a rotational motion, and includes a journal (main shaft), a pin to which a piston is connected via a connecting rod, an arm for connecting a balance weight and an integrated journal and pin. It consists of
The crankshaft is an important part of the engine and is required to be lightweight and inexpensive as well as quality and durability. Some small ones are made by casting. , And the forging die in which the arm is integrated.

The crankshaft of a multi-cylinder engine such as a 6-cylinder or 8-cylinder engine rotates each pin by a predetermined angle (60 degrees or 120 degrees for a 6-cylinder engine) so that a smooth rotation can be obtained. Arranged.
When a crankshaft with pins arranged in this way is manufactured by forging, it can not be die-cut with the finished shape, so it is manufactured by twist forging that forges in a shape that is easy to die-cut and then twists to a predetermined angle at high temperatures. Has been.
The crankshaft made in this one-piece structure has to have a two-part structure for the bearing mounted on the journal and pin, which not only increases the manufacturing cost and weight, but also slides the sliding surface between the shaft and the bearing. Increased dynamic resistance tends to cause deterioration in driving performance and fuel consumption. In addition, twist forging requires a large dedicated hydraulic press and has a problem that it takes a long processing time.

The applicant first manufactured an assembled crankshaft for an automobile engine in which a journal, a pin, and an arm are separately manufactured, a ring-shaped bearing is incorporated in the journal and the pin, and then fixed to the arm. Developed (Patent Document 1).
This crankshaft has a journal and pin as a hollow shaft, and connecting shafts are provided at both ends. The arm is integrally formed with a balance weight and is fitted on a conical surface to which the connecting shaft is fitted. A shaft hole is provided. And assembling, after attaching a ring-shaped bearing to the journal and the pin, the connecting shaft is fixed to the shaft hole for fitting by shrinking.

Utility Model Registration No. 3129273

The crankshaft disclosed in Patent Document 1 has not only been mass-produced with high quality but also significantly reduced weight by making the journal and the pin into a hollow shaft shape and accurately making the arm by die forging. However, in the case of a crankshaft of a multi-cylinder engine, there is a problem that it is difficult to align the arms when the arms are shifted by a predetermined angle, and skill is required.
Naturally, the alignment is performed using a jig, but the journal and pins are fixed by shrinkage, so the position must be aligned when the arm is heated, and it is difficult to do it reliably in a short time. . Furthermore, there is a slight concern about the reliability of fixing due to shrinkage, and further weight reduction is desired.

  Accordingly, an object of the present invention is to provide a lightweight and high-quality assembled crankshaft that can be applied to a multi-cylinder engine.

  The crankshaft for an automobile engine of the present invention employs the following means in order to achieve the above object. That is, in a crankshaft of an automobile engine in which pins connected to pistons of cylinders by connecting rods are rotated by a predetermined angle in a plane perpendicular to the center axis, the journal and the pins have pyramidal surfaces at both ends. Each connecting part extends, and the arm is provided with a pyramid hole in which the balance weight is integrally formed and the connecting part is fitted, and the connecting part of the journal and the pin is fixed to the pyramid hole by shrinking. The connecting portion of the journal and the pin is symmetrically formed so that the pyramid hole corresponding to the connecting portion of the journal is rotated by the predetermined angle, or the connecting portion of the journal of each arm is connected. All the pyramid holes that fit into the part are the same, and the connecting part at one end of the journal is rotated by the predetermined angle relative to the connecting part at the other end Is characterized in that form was.

The present invention is an assembly-type crankshaft that is manufactured by individually manufacturing a journal, a pin, and an arm and fixing them, and is particularly applicable to a multi-cylinder engine.
The pin is arranged by being rotated by a predetermined angle in a plane perpendicular to the central axis of the crankshaft. There are various angles depending on the type of engine and the number of cylinders. In the present invention, the journal, the pin, and the arm are automatically aligned by fitting a connecting portion having a pyramid surface into the pyramid hole. It can also be applied to any angle.
The fitting pyramid surface and the pyramid hole are not strictly defined, and may be, for example, a part of a conical shape that is cut flat.

The journals are formed symmetrically and the pyramid holes of the arm are rotated by a predetermined angle so that the arms fixed to the connection parts at both ends of the journal are fitted in a state rotated by a predetermined angle around the center of the journal. To do. Alternatively, all the pyramid holes fitted to the connecting portions of the journal of each arm may be the same, and the connecting portion at one end of the journal may be rotated by the predetermined angle with respect to the connecting portion at the other end.
The journal and pin may be cut from a round bar. Further, it is desirable that the arm with an integrated balance weight is subjected to coining immediately after hot forging and trimming to have high dimensional accuracy so that cutting with a machine tool is minimized. In addition, the pyramid surface and the pyramid hole to which the shrinkage is fixed are manufactured with high accuracy by machining.

  When the journal is positioned directly above the pin, the balance weight is an arc centered on the journal axis, and has a fan shape with the vicinity of the center line in the horizontal direction of the journal as the base. And the lower end of the arm is shaped to be inscribed in a circular arc of the outer edge of the balance weight with the axis of the journal as the center (Claim 2). ) Is desirable. In order to prevent stress concentration from thick to thin, it is preferable to have a continuous curved surface or slope.

The crankshaft for an automobile engine according to the present invention has a journal and pin connecting portion fixed to a pyramid hole by shrinkage and assembled, and the journal and pin connecting portion is symmetrical and connected to the journal. Since the pyramid hole corresponding to is formed by rotating a predetermined angle, the arm can be assembled easily and accurately with the arm rotated by a predetermined angle. Further, the assembled product has no slip in the rotating direction, and there is no concern about the reliability of the shrinkage.
The same effect can be obtained when the pyramid holes fitted to the journal connecting portions of each arm are all the same, and the connecting portion at one end of the journal is rotated by a predetermined angle with respect to the connecting portion at the other end.

  The balance weight of the arm is an arc centered on the journal axis, and is formed in a fan shape with the vicinity of the center line in the horizontal direction of the journal as the base end. If it is formed thin (Claim 2), it can be made light, compact and well-balanced.

Hereinafter, embodiments of the crankshaft of the present invention will be described with reference to FIGS. FIG. 1 is a perspective view showing a schematic configuration of a crankshaft for a V-type 6-cylinder engine according to the present invention, and FIG. 2 is a plan view in the vicinity of the arms 10C and 10D, which are a part thereof.
3 to 7 show details of the constituent members. FIGS. 3 and 4 are a front view and a side view of the journal and the pin, and FIGS. 5 and 6 are a side view and a front view of the arm. 7 is an AA view, a BB view, and a CC view in FIG.
As shown in FIG. 1, the crankshaft 1 connects six arms 10A, 10B, 10C, 10D, 10E, and 10F with journals 2K, 2L, 2M, and 2N and pins 3K, 3L, and 3M. An end shaft is fixed, and a flywheel is connected to the other end.

As shown in FIG. 2, this connection is performed by assembling the journals 2L and 2M and the pin 3L by arranging the respective axes in a stepped manner via the arms 10C and 10D integrated with the balance weight 11. It has been. In assembly, ring-shaped bearings are preliminarily fitted onto the journals 2L and 2M and the pins 3L.
In FIG. 1, pins 3K, 3L, and 3M are connected to pistons of respective cylinders of the engine by connecting rods, but each of them has a predetermined angle (120 degrees in this case) in a plane perpendicular to the central axis of the crankshaft 1. They are staggered.
Next, details of the components shown in FIG. 2 will be described.
First, as shown in FIG. 3, the journals 2L and 2M have connecting portions 2b having pyramidal surfaces at both ends of the pin portion 2a, and the pins 3L have both ends of the pin portion 3a as shown in FIG. Has a connecting portion 3b having a pyramidal surface. The journals 2L and 2M and the pin 3L are manufactured by machining steel bars.

As shown in FIGS. 5 and 6, the arm 10 </ b> D is integrally formed with a balance weight 11, and is provided with pyramid holes 15 and 16 into which the connecting portions 2 b and 3 b of the journal 2 </ b> M and the pin 3 </ b> L are fitted.
The overall size is a size that fits in a circle of R (about 150 mm) centered on the axis of the journal 2M, and the thickness is about 16 mm.
When the connecting portion 16 of the pin 3L is positioned directly below the center of the pyramid hole 15 to which the journal 2M is fixed (axial center of the journal 2M), the balance weight 11 is positioned at the upper part, and the Japanese hair is almost It is shaped like the face of a tied woman.

  The balance weight 11 is formed in a fan shape of approximately 150 degrees, and the fan-like base end is on the horizontal center line of the journal 2M. The fan-shaped outer edge portion is formed to have a cross section of approximately 16 mm square, and the inner side (near the journal 2M) is formed as a 5 mm thin wall that is recessed on both the front and back sides to form a recess 12. In addition, the recessed part 12 is connected with the inclination of about 30 degree | times from the outer edge part.

The lower part of the arm 10D has a shape that is curved from the center of the pin 3L to the arc of a radius of about 30 mm and the base end of the fan-shaped balance weight 11, and the lower end is about 150 mm of the arc of the outer edge of the balance weight 11. Inscribed in a circle.
Boss portions 13 and 14 having a thickness of about 3.5 mm are formed on the surface on which the journal 2M and the pin 3L are fixed.
The balance weight 11 is provided with bosses 17a, 17b, and 17c at the upper end, the front surface at the upper end, and the left and right ends, and boss 17d at the left and right ends of the arm 10D. This is for stamping the oil passage and the markings for identification.

The arm 10D is made by performing a coining process in which the arm 10D is immediately placed in a closed mold and pressed after hot forging and then trimmed. According to this, the concavo-convex shape of the mold forming surface can be efficiently and accurately transferred, so that a high dimensional accuracy can be achieved. Thereafter, the pyramidal holes 15, 16 are machined.
As for the assembly of the crankshaft, the journal 2M and the pin 3L are fitted into the pyramid holes 15 and 16 of the arm 10D after extrapolating a ring-shaped bearing (not shown) from the shaft end. As a result, the position of the arm 10D with respect to the axis of the journal 2M is automatically determined, and is fixed by shrinkage.
Shrinking is for rapidly cooling the arm 10D by fitting the journal 2M and the pin 3L into the pyramid holes 15 and 16 which are expanded by heating the arm 10D.

In the crankshaft 1 shown in FIG. 1, the pins 3K and 3M are the same as the pin 3L, and the journals 2K and 2N have a connecting portion 2b on the side fixed to the arm, but the opposite side is different. To do. The arms 10A, 10B, 10C, 10D, 10E, and 10F are the same except for the pyramid hole 15. If the pyramid hole 15 is based on the arms 10C and 10D, the arms 10A and 10B and the arms 10E and F are respectively opened by being inclined 30 degrees to the left and right.
That is, as shown in FIG. 7A, the arm 10D in FIG. 1 is located right side as viewed in FIG. 7A, and the arm 10B is as shown in FIG. 7B in BB view. The pin 3K is assembled at a position rotated 120 degrees counterclockwise. Further, the arm 10F is assembled so that the pin 3M is rotated 120 degrees clockwise as shown in FIG. 7C in CC view.

Next, another embodiment will be described with reference to FIGS.
In the above embodiment, the connecting portions at the left and right ends of the journal are all the same symmetrically, and the pyramid hole of the arm into which the journal is fitted is formed in a state rotated by a predetermined angle.
Another embodiment is solved by changing the connecting portion of the journal without changing the pyramid hole of the arm.
That is, the arm is only one type of arm 10D shown in FIG. 6, and the journal 2L in FIG. 1 is changed to the journal 22L shown in FIG. 8, and the journal 2M is changed to the journal 22M shown in FIG. The journal 22L has a pyramidal surface with the left end connecting portion 22c rotated counterclockwise by 30 degrees with respect to the right end connecting portion 22b, and the journal 22M has a right end connecting portion 22d with respect to the left end connecting portion 22b. Is a pyramid surface rotated clockwise by 30 degrees.

  Thus, the journal 22L can be easily assembled into the positional relationship between the arms 10B and 10C in FIG. 1, and the journal 22M can be easily assembled into the positional relationship between the arms 10D and 10E.

  In the above description of the embodiment, the arm is shown with specific dimensions so that the contents of the invention can be understood well. However, it goes without saying that the present invention is not limited to this dimension. Absent.

The embodiment of the crankshaft for the automobile engine of the present invention is shown, and is a model perspective view for a 6-cylinder engine. FIG. 2 is a plan view showing details of the portion (arms 10C, 10D) of FIG. It is the front view and side view which show the journal 2L and 2M. It is the front view and side view which show pins 3L and 3M same as the above FIG. 3 is a side view of the arm in the AT-AT view of FIG. 2. FIG. 2 is a front view of the arm. FIG. 2 is a front view of arms 10D, 10B, and 10F in FIG. It is the front view and side view of the journal 22L which show another embodiment same as the above. It is the front view and side view of the journal 22M which show another embodiment same as the above.

Explanation of symbols

1 Crankshaft 2K, 2L, 2M, 2N Journal 3K, 3L, 3M Pin 2a Journal 2b Connection 3a Pin 3b Connection 10A, 10B, 10C Arm 10D, 10E, 10F Arm 11 Balance weight 12 Recess 13, 14 Boss Part 15 Pyramid hole 16 Pyramid hole 17a, 17b, 17c, 17d Boss 22L, 22M Journal 22a Pin part 22b, 22c, 22d Connecting part

Claims (2)

  In a crankshaft of an automobile engine in which pins connected to pistons of cylinders by connecting rods are rotated by a predetermined angle in a plane perpendicular to the central axis, a connecting portion having pyramid surfaces at both ends of the journal and the pins The arm is provided with a pyramid hole in which a balance weight is integrally formed and the connecting part is fitted, and the connecting part of the journal and the pin is fixed to the pyramid hole by shrinking and assembled. The connecting portion of the journal and the pin is symmetrically formed by rotating a predetermined pyramid hole corresponding to the connecting portion of the journal by the predetermined angle, or with the connecting portion of the journal of each arm. All of the pyramid holes to be fitted are the same and formed by rotating the connecting portion at one end of the journal to the connecting portion at the other end by the predetermined angle. Crankshafts for automobile engines, wherein.   When the journal is positioned directly above the pin, the arm has a circular arc centered on the journal axis, and a fan shape with the vicinity of the horizontal center line of the journal as a base. The outer edge of the arm is formed thicker and the journal side is formed thinner. Further, the lower end of the arm is inscribed in a circle of the arc of the outer edge of the balance weight centered on the axis of the journal. The crankshaft for an automobile engine according to claim 1.

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