JPH0447172B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for forming a plain bearing that is press-fitted into the large end of a connecting rod and arranged between the connecting rod and a crank pin.

[Prior Art] Generally, in an engine, the large end of a connecting rod is connected to the crank pin of the crankshaft via a large end bearing, and the piston is connected to the small end of the connecting rod via a piston pin. This allows the reciprocating motion of the piston caused by the explosion pressure within the cylinder to be converted into rotational motion of the crankshaft via the connecting rod. Here, a large load is applied to the crank pin of the crankshaft due to the explosion pressure inside the cylinder, and
During high-speed rotation, a large inertial force acts due to the mass of the crank pin itself, the connecting rod, the piston pin, and the piston. Further, a large load due to the explosion pressure within the cylinder acts on the big end bearing, and a large inertial force based on the respective masses of the connecting rod, piston pin, and piston acts on the large end bearing during high-speed rotation.

Therefore, in conventionally known engines, the large end of the connecting rod using a plain bearing is divided into two, and the plain bearing serving as the large end bearing is also divided into two, and the large end of each of these two halves is divided into two. There is a type (hereinafter referred to as a first conventional example) in which a flat bearing is mounted on the outer circumference of a crank pin, and the two divided large ends are integrated by bolting.

In addition, there is a prefabricated crankshaft in which an undivided large end of a connecting rod is connected via a needle bearing to a crankpin that can be press-fitted into a web (hereinafter referred to as a second conventional example).

Furthermore, conventionally, in connection bearings for trailer connection rods, the boring process of the inner diameter of the bushing is configured in the form of a continuous ellipse, and the long axis of the ellipse is arranged perpendicularly to the axis of the connection rod (for example, the bearing of the USSR Invention Patent No. 224966).
There is also a third conventional example) (refer to the specification of the No.

By applying the technology of this third conventional example to the flat bearing inserted into the large end of the connecting rod, the weight of the connecting rod can be reduced, and the inertial force that acts on the crank pin, flat bearing, etc. during high-speed rotation can be reduced. It becomes possible to make it small,
In addition, even if the flat bearing inserted into the large end of the connecting rod is pulled and deformed in the direction of the reciprocating movement of the piston, the inner diameter of the inner circumference of the flat bearing is maximum at the part perpendicular to the axis connecting the small end and the large end, so there is no rubbing area between the inner periphery of the plain bearing and the outer periphery of the crank pin, and there is no friction between the two. Since sufficient lubricating oil is supplied and seizure does not occur, it is possible to expect effects such as a significant extension of the service life of the plain bearing.

[Problems to be Solved by the Invention] By the way, in the above-mentioned known engine, the first
In the conventional example, the weight of the large end of the connecting rod increases by the weight of the bolt, increasing the inertia weight.
Not suitable for high-speed rotating engines. In addition, in the second conventional example, since the outer diameter of the needle bearing is relatively large, the shape of the large end of the connecting rod must be large, and the weight of the large end becomes large. Not suitable for use in engines such as
There is a problem with this.

Furthermore, in the third conventional example, it is very difficult to perform boring into a continuous ellipse. That is,
It is conceivable to use a single-axis boring machine or a two-axis boring machine. In the case of a single-axis boring machine, after some machining has been completed, the boring axis must be accurately shifted slightly in the long axis direction to continue machining, so it is necessary to manage the dimension of this shift and to adjust the tool. This work is extremely difficult as it is necessary to always accurately manage dimensions to accommodate changes in the amount of boring due to wear. Also, in the case of a two-axis boring machine with two axes that are offset in the major axis direction from the beginning, the inner diameter (ellipse or ellipse) is measured because the tool wears out during machining and the inner diameter gradually becomes smaller. However, since the wear of each tool on the two shafts is not the same, the result is an irregular ellipse or ellipse, and even if this dimension is measured, the normal bearing clearance cannot be maintained. It is difficult to form accurate inner diameter dimensions for Furthermore, it is necessary to replace the tool when it wears out to a certain extent, but there is a problem in that it is troublesome and takes a lot of time to replace the tool with two biaxial tools.

This invention has been made in view of the problems of the prior art, and its purpose is to reduce the weight and inertial mass of the large end of the connecting rod, and to prevent seizure. The purpose of this invention is to provide a plain bearing for a connecting rod, which is conventionally available, by a simple molding method.

[Means for Solving the Problems] In order to achieve the above object, the method for forming a plain bearing in a connecting rod of the present invention is as follows: The inner diameter of the intermediate molded product is machined into a perfect circle in this state, and the processed product is press-fitted into the hole of the hole with an oval or elliptical opening. The connecting rod is press-fitted into a perfect circular hole at the large end of the connecting rod so that the press-fitting direction of the short axis coincides with the direction perpendicular to the axis connecting the large and small ends of the connecting rod.

[Operation] If the hole shape is finished into an oblong or elliptical shape, it is only necessary to press fit a cylindrical flat bearing intermediate molded product into it and process its inner diameter into a perfect circle using a single-axis boring machine. This simplifies the adjustment work. Moreover, if the hole pattern is made sufficiently accurately and has wear resistance, a large number of bearings can be machined with one hole pattern.

[Examples] Examples of the present invention will be described below with reference to the drawings.

In the motorcycle shown in Fig. 1, frame 1
1 is equipped with a V-type 4-cylinder engine 12, a front wheel 14 is pivotally supported at the front part of the frame 11 via a front fork 13, and a steering handle 15 is provided, and a rear suspension 16 is installed at the rear part of the frame 11. A rear wheel 18 is pivotally supported by a rear arm 17 that is urged downward by a rear arm 17 . frame 1
A fuel tank 19 and a seat 20 are attached to the upper part of the vehicle 1, and a passenger can sit on the seat 20.

As shown in FIG. 2, in the engine 12, a crankshaft 22 is rotatably supported by a crankcase 21, and pistons 22 are installed in cylinder liners 23 provided for each of the four cylinders, two front and rear.
4 is housed so that it can be reciprocated by the explosion pressure. The reciprocating motion of the piston 24 rotates the crankshaft 22 via a connecting rod 25, and further enables the rear wheel 18 to rotate via a crank gear 26, a clutch gear 27, a clutch 28, a transmission, etc.

The connecting rod 25 is connected to the main body 2 as shown in FIG.
9, consisting of a small end 30 and a large end 31. A bearing 32 is press-fitted into the small end 30 of the connecting rod 25, and the piston 24 is connected to the piston 24 via a piston pin pivotally supported by the bearing 32. Connecting rod 25
The large end portion 31 of is integrally formed in an undivided manner, a flat bearing 33 is press-fitted therein, and the large end portion 31 is connected to the crank pin of the crankshaft 22 as will be described in detail below.

Here, the flat bearing 33 press-fitted into the large end 31 of the connecting rod 25 is manufactured according to the manufacturing process shown in FIGS. 4A to 4E. That is, the material 33A is made by cutting a bimetallic material with white metal, kelmet metal, etc. placed on the back metal of an iron plate.
After forming into a cylindrical shape as shown in FIG. 4A to FIG. 4B and determining the width, the outer periphery is polished, and the intermediate molded product 3
Get 3B. This intermediate molded product 33B is then press-fitted into an oblong or elliptical hole mold 34 with a major axis L1 and a minor axis L2, as shown in FIG. 4C. The intermediate molded product 33B press-fitted into the hole mold 34 is
As shown in FIG. 4D, the inner diameter portion is bored and the inner diameter d is finished into a perfect circle.
That is, the bored workpiece 33 shown in FIG. 4D has a large wall thickness in the vertical direction and a small wall thickness in the lateral direction. By removing this processed product 33 from the hole mold 34, the restriction of the hole mold 34 is removed, and as shown in FIG. In the figure, the inner peripheral shape is an oval or elliptical shape in which the inner diameter d2 in the horizontal direction is larger than the inner diameter d1 in the vertical direction, and is further subjected to necessary treatments such as plating to form the plain bearing 33 as a final product. Become.

When the flat bearing 33 is press-fitted into the perfectly circular inner diameter portion of the large end 31 of the connecting rod 25, as shown in FIG. It is set to be larger than the inner diameter d1 in the direction. That is, in the case of the large end bearing of the connecting rod 25, the inner diameter of the inner circumferential portion thereof is the same as that of the small end portion 3 of the connecting rod 25.
d2 is maximum at a portion perpendicular to the axis connecting the large end portion 31 and the large end portion 31. Therefore, when the plain bearing 33 is connected to the crank pin as described later, there is a gap between the bearing and the crank pin with the maximum inner diameter d2.
A large oil clearance is formed in the horizontal direction, and even when the plain bearing 33 is deformed in the vertical direction under the action of an excessive bearing load, this clearance in the horizontal direction does not disappear.

The connecting rod 25 is connected to the crankshaft as shown in FIG. That is, as shown in FIG. 5, the crankshaft 22 has an intermediate journal part 35 and webs 36 on both sides thereof integrally formed, and each journal part 37 at both ends, each crank pin 38, and a web 39 are integrally formed. , a web 36 integrally formed with the intermediate journal portion 35
Each crank pin 3 is inserted into the insertion hole 40 provided in the
By press-fitting the end portions of 8, the entire structure is integrated, and the intermediate journal portion 35 and each journal portion 37 at both ends are pivotally supported by a main bearing 41 formed in the crankcase 21. Further, before each crank pin 38 is press-fitted into a fitting hole 40 of a web 36 integrally formed in an intermediate journal portion 35 of the crankshaft 22, the connecting rod 2
5 is connected to each crank pin 38 via a press-fitted plain bearing 33. That is, the undivided large end portion 31 of the connecting rod 25 and the flat bearing 33 can be attached to each crank pin 38 of the crankshaft 22 . Furthermore, this engine 12
is V-shaped, so each crank pin 3
8 to which two connecting rods 25 can be connected. Furthermore, the intermediate journal portion 3 of the crankshaft 22
5 is formed with an oil passage 42, and each crank pin 38 is formed with an oil passage 43 on its axis.
The oil passage 42 and the oil passage 43 are communicated with each other. Also,
An oil passage 44 is formed in the intermediate journal portion 35,
The oil passage 44 allows lubricating oil, which is pumped by an oil pump, to be introduced into the oil passage 42 from an oil passage formed in the crankcase 21 . Each crank pin 38 has a large end 3 of each of the two connecting rods 25.
An oil passage 45A and an oil passage 45B respectively corresponding to the flat bearing 33 press-fitted into the bearing 1 are provided, and each of the flat bearings 33 can be lubricated via each oil passage 45A, 45B.

According to this embodiment, as the engine 12 operates, the piston 24, the connecting rod 25, the crankshaft 2
2. The rear wheel 18 is driven via the crank gear 26, clutch gear 27, clutch 28, transmission, etc., and is inserted into the large end 31 of the connecting rod 25 by the reciprocating motion of the piston 24. Plain bearing 33
Even if it is pulled and deformed in the reciprocating direction of the piston 24, the inner diameter of the inner circumferential portion of the plain bearing 33 reaches its maximum at a portion perpendicular to the axis connecting the small end and the large end. Therefore, there is no friction between the inner periphery of the plain bearing 33 and the outer periphery of the crank pin 38, and sufficient lubricating oil is supplied between the two, so that seizure does not occur.

In addition, although the embodiment described above is applied to a V-type engine, the present invention is also applicable to an in-line engine.

[Effects of the Invention] This invention makes it possible to reduce the weight and inertial mass of the large end of the connecting rod, thereby increasing the speed of the engine. A simple method of forming the flat bearings to be charged is to press fit the cylindrical flat bearing intermediate molded product into a hole finished in an oval or elliptical shape, and then make the inner diameter a perfect circle using a single-axis boring machine. Since only processing is required, the adjustment work is greatly simplified. Furthermore, if the hole shape is made sufficiently accurately and has wear resistance, a large number of bearings can be easily machined with one hole shape, and manufacturing costs can be kept low.

[Brief explanation of drawings]

Fig. 1 is a side view showing a motorcycle to which this invention is applied, Fig. 2 is a plan view showing an embodiment to which this invention is applied, with main parts cut away, and Fig. 3 is a connection in the same embodiment. Front view showing the rod taken out, No. 4
Figures A to E are process diagrams showing the process of manufacturing the large end bearing of the connecting rod in the same embodiment, and Fig. 5 is a sectional view showing the state of connection between the crankshaft and the connecting rod in the same embodiment. 22...Crankshaft, 24...Piston, 25
...Connecting rod, 30...Small end, 31...Big end,
33...Flat bearing, 33B...Flat bearing intermediate molded product,
34...Hole type, 38...Crank pin, L1...
Long axis, L2... Short axis, d1, d2... Inner diameter.

Claims (1)

[Claims] 1. In a method for forming a plain bearing in a connecting rod, which has a small end that is pivotally supported at one end on a piston pin and a large end that is pivotally supported on the other end on a crank pin of a crankshaft, a cylindrical plain bearing intermediate molded product is used. , the intermediate molded product is press-fitted into a hole having an elongated or elliptical opening in directions perpendicular to each other, and the inner diameter of the intermediate molded product is machined into a perfect circle, and the processed product is The connecting rod is press-fitted into the perfect circular hole at the large end of the connecting rod so that the short axis press-fitting direction when the connecting rod is press-fitted into the hole in the hole is aligned with the direction perpendicular to the axis connecting the large and small ends of the connecting rod. Forming method for plain bearings in connecting rods.