JPS5891917A - Crankshaft - Google Patents

Abstract

PURPOSE:To change reciprocating inertial mass balance and moment of inertia, by providing a mounting fixture to a crankshaft, whereby a U-shaped web is parallelly fitted to the crank center line and its both ends are tightened to a crank arm then forcibly attached to said arm. CONSTITUTION:A U-shaped web 10 in thickness almost equal to or slightly larger than a thickness of a crank arm 3, further having an internal peripheral surface of equal radius to a circumferential surface of the arm 3 and a circumferential peripheral surface of radius B from the center of a shaft part 2, is formed, and a hole 12 inserted with a bolt 13 is provided in a notch stepped part 11 formed in both end parts of the web 10, while a semi-circular arc 4a fitted with a shaft part of the bolt 13 is formed in a chord part 4 of the arm 3, and the bolt 13 is fitted to the hole 12 of the part 11 and fitted also to a groove 4a of the part 4, then a nut 14 is screwed to a bolt screwed part 13a protruded from said part 11.

Description

DETAILED DESCRIPTION OF THE INVENTION In an internal combustion engine, in order to balance the inertial force of reciprocating masses such as pistons and connecting rods, conventionally, as shown in FIGS. The web C is fixed to the crank 7-m b with two poles d so that the web C is located at However, in a crankshaft with such a structure, as the weight of the web changes, the balance of the reciprocating mass described above also changes, making it difficult to use a common shaft in the center of the crankshaft. Ta.

The present invention relates to an improvement of a crankshaft that overcomes these difficulties, and its purpose is to provide an inexpensive crankshaft that balances the inertial force of the reciprocating mass and can appropriately change the moment of inertia.

An embodiment of the present invention illustrated in FIGS. 3 and 4 will be described below.

1 is the crankshaft of a single-cylinder engine, and its shaft portion 2
A crank bin 4 is integrally formed on the coaxial part 2 via a crank arm 3 so that the crank bin 5 is located at a position eccentric by R1 from the shaft part 2. It is formed into a disk shape with a radius A centered at a point that is centered by R7 toward the installation location 5.

Furthermore, one of the pair of left and right crank arms 3 (second
Is the crank arm 3 on the left side in the figure facing towards the crank bin 5? A hole 6 is provided, an oil passage 7 is communicated from the outer peripheral surface of the shaft portion 2 toward the opening 6, and an oil passage 8 is provided from the circular hole 6 toward the outer peripheral surface of the crank pin 5. 6
A blind plug 9 is fitted to the crank pin 5 , and a portion of the oil injected into the shaft portion 2 from the crank casing (not shown) passes through the oil passage 7 , the hole 6 and the oil passage 8 to the crank pin 5 .
It is designed to be supplied to the outer peripheral surface of the

Furthermore, an inner circumferential surface approximately equal to or somewhat thicker than the crank arm 3 and having the same radius as the circumferential surface of the crank arm 3, and an outer circumferential surface having a radius B from the center of the shaft portion 2. A horse-shaped web 10 is formed.

Moreover, cutout steps 1 are provided at both ends of the horse frame shaped web 10.
1 is formed, and a hole 2 into which a bolt 13 is inserted is provided in the stepped notch 11.
A semi-circular groove 4a into which the shaft portion of the bolt 13 can fit is formed in the crank arm portion 4, and when the bolt 13 is fitted into the hole 12 of the notch step portion 11, both crank arm grooves 4a are formed. A nut 14 is screwed onto a bolt thread part 13 a which is fitted into a groove 4 a of the part 4 and protrudes from the stepped notch part 11 .

A circular hole 15 is formed across the outer circumferential surface of the rank arm 3 and the inner circumferential surface of the horse-shaped web 10, and a positioning pin 16 is fitted into the circular hole 15.

The embodiment shown in FIGS. 3 and 4 is constructed as described above, so that the moment of inertia that matches the rotational speed of the single-cylinder engine and the inertial force of the reciprocating mass of the piston pin and connecting rod (not shown) are maintained. A horse-shaped web 10 having a mass sufficient for balance is selected, and the web 1
0 to the left and right pair of crank arms 3, positioning pins 16 are fitted into the circular holes 15 for positioning, and the holes 12 of the web notch stepped portion 11 and the crank arm technical parts 4 are fitted.
The horse-shaped web 10 can be integrally attached to the crank arm 3 by inserting the bolt 13 into the groove 4a and tightening the nut 14 onto the threaded portion 13a of the bolt 13.

The crankshaft constructed in this way can always balance the inertial force of the reciprocating mass by appropriately selecting the horse-shaped web 10 to match the characteristics of the engine.

Moreover, the thickness of the horse-shaped web 10 can be formed thick without being restricted by the thickness of the notched disc-shaped crank arm 3.

Furthermore, since the outer diameter of the crank arm 3 is small, when forging the crankshaft 1, there is no need to reduce the drafting slope and the forging depth is also shallow, improving workability and reducing costs.

In the embodiment described above, the notched step portions 11 at both ends of the horse-shaped web 10 are tightened with bolts 13 and nuts 14, but both the ends 11 may be tightened with stud bolts.

As described above, the present invention provides a crank fastening tool that tightens both ends of a horse frame-shaped web that is fitted onto a crank arm in a direction parallel to the crank center line, and press-fits the web to the crank arm. By appropriately selecting the horse-strain-shaped mob provided on the shaft, it is possible to manufacture a rank shaft that balances the inertial force of the reciprocating mass and selects a moment of inertia that matches the rotational speed of the engine. .

In addition, in the present invention, the crank arm 3 and the paralyzed web 10, which serves as a weight, are constructed separately, making it possible to easily create a draft angle when machining the crankshaft. In addition, the machining depth can be reduced, and as a result, machinability can be improved and costs can be reduced.

Although the present invention has been described above in detail with respect to the embodiments shown in the drawings and the embodiments not shown in the drawings, the present invention is not limited to these embodiments and examples, and may be implemented without departing from the spirit of the invention. The design can be freely modified as necessary.

[Brief explanation of the drawing]

1 is a partially longitudinal side view of a conventional crankshaft, FIG. 2 is a partially sectional front view of FIG. 1, and FIG. 3 is a side view illustrating an embodiment of the crankshaft according to the present invention. FIG. 4 is a longitudinal sectional view taken along the line IV--IV in FIG. 3. 1... Crankshaft, 2... M section, 3°...
Crank arm, 4... Crank arm technical department, 5...
・Crank pin, 6... Hole, 7.8... Oil passage, 9... Blind plug, 10... Horseshoe shaped web, 11...
・Notch step, 12...hole, 13...bolt, 14
... Nut, 15...", circular hole, 16... positioning pin. Leather 1 Figure 2

Claims (1)

[Claims] It is characterized by comprising a horseshoe-shaped web that is fitted onto the crank arm along a direction parallel to the crank center line, and a fastener that tightens both ends of the horseshoe-shaped web and press-fits the web to the crank arm. Crankshaft.