JP3984673B2 - Connecting rod - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a connecting rod that converts a reciprocating motion of a piston into a rotational motion of a crankshaft in an internal combustion engine, an air compressor, or the like.
[0002]
[Prior art]
In an internal combustion engine, an air compressor, etc., a connecting rod used as a joint that converts a reciprocating motion of a piston into a rotational motion of a crankshaft has a small end portion for mounting the piston on one end side of the rod portion, and on the other end side. A large end portion is provided, and a crank pin is fixed to the large end main body of the large end portion by a large end cap and a rod bolt via a large end bearing or the like. Further, in the connecting rod in which the split surface of the large end portion is formed obliquely, the split surface and the axis of the rod bolt are configured perpendicularly. Alternatively, there is an example in which the rod bolt is formed to bend inward. For example, this is the technique described in Japanese Patent Application Laid-Open No. 7-243433.
[0003]
Recently, as the internal combustion engine has become smaller and lighter, the connecting rod itself has been required to be smaller and lighter. The connecting rod has a minimum required rigidity and is compact in size. The size and weight are reduced. However, in such a connecting rod, when the rotational speed is increased, bending stress acts on the large end body and the large end cap, and bending deformation to the outside of the large end body and large end cap occurs. To do. That is, the opening of the split surface occurs and the reliability durability of the connecting rod is reduced.
[0004]
As a countermeasure against the opening of this split surface, that is, the joint of the large end main body and the large end cap, the axial force is increased by changing the size and material of the rod bolt, and the surface pressure of the entire joint surface is increased. The surface pressure of the mouth opening portion was increased by raising it. In addition, the rod bolt is arranged on the outer edge of the connecting rod as much as possible to increase the area of the joint surface between the large end body and the large end cap to achieve uniform surface pressure, and to reduce the surface pressure at the mouth opening. It was increasing.
[0005]
[Problems to be solved by the invention]
However, if the above countermeasures are taken, the weight and dimensions of the connecting rod and rod bolt will increase and the cost will be increased, so the connecting rod itself and rod bolt will become smaller and lighter. There was no room for strength and dimensions, and it was not possible to implement. Therefore, the present invention increases the safety factor of the mouth opening while maintaining the same axial force and the same shape as before, and improves the reliability durability of the connecting rod.
[0006]
[Means for Solving the Problems]
The problems to be solved by the present invention are as described above. Next, means for solving the problems will be described.
The split surface that divides the large end portion (7) into the large end portion main body (3) and the large end portion cap (4) has an obliquely divided two-part structure, and the split surface of the large end portion main body (3); The angle (A) formed by the line connecting the arc center of the small end portion (2) of the rod portion (1) and the arc center of the large end body (3) is configured to be smaller than 90 degrees, Two rod bolts inserted into the connecting rod (3b, 3b ′) side of the large end body (3) and the mounting surface (4b, 4b ′) side of the large end cap (4) of the connecting rod ( 5 and 5) , only the rod bolt (5) on the mounting surface (3b) and mounting surface (4b) side of the rod bolt (5) is connected to the tip end of the rod bolt (5). The mounting surfaces (3b, 3b ′) and the mounting surfaces (4b, 4b ′) and the axis of the rod bolt (5) are tilted in the direction toward the outer edge of the rod bolt (5). The inclination angle (θ) to be formed is configured to satisfy 90 ° <θ <95 ° .
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Next, an embodiment of the present invention will be described. FIG. 1 is an overall front view showing a connecting rod of the present invention, FIG. 2 is a partial cross-sectional view showing a fastening portion by a rod bolt between a large end body and a large end cap, and FIG. 3 is a view of a rod bolt with respect to a connecting rod split surface. It is a graph which shows the relationship between inclination-angle (theta) and a mouth opening safety factor.
[0008]
First, the connecting rod of the present invention will be described with reference to FIGS. A small end portion 2 is provided on one end side of the rod portion 1, and a through-hole portion 2a for attachment of the small end portion 2 is connected to a piston (not shown). On the other end side of the rod portion 1, a large end portion 7 connected to a crank pin (not shown) is disposed. The large end 7 is divided into a large end main body 3 and a large end cap 4, and the large end main body 3 and the large end cap 4 are connected and fixed by rod bolts 5.
[0009]
The large end body 3 includes a mounting portion 3a formed in a substantially semicircular arc shape for mounting a crankpin on the tip side thereof, and mounting surfaces 3b and 3b for mounting the large end cap 4 on both sides of the mounting portion 3a. 'And have. As shown in FIG. 2 (only the attachment surface 3b side is shown in FIG. 2), fixing holes 3c and 3c ′ formed in a cylindrical shape are formed in the attachment surfaces 3b and 3b ′. Female screw portions 3d and 3d 'are formed on the inner peripheral walls of the holes 3c and 3c' so that they can be screwed into the screw portion 5a of the rod bolt 5.
[0010]
The large end cap 4 has a semicircular mounting portion 4a for attaching a crank pin to one end side thereof, and mounting surfaces 4b and 4b 'provided on both sides of the mounting portion 4a. The mounting surface 4b -4b 'is arrange | positioned facing the said mounting surface 3b * 3b'. Cylindrical fixing holes 4c and 4c ′ penetrating from the mounting surfaces 4b and 4b ′ to the shoulder portions 4e and 4e ′ are formed in the mounting surfaces 4b and 4b ′, and the fixing holes 4c and 4c ′ are formed. The rod bolt 5 can be inserted freely.
[0011]
When the mounting surfaces 3b and 3b 'and the mounting surfaces 4b and 4b' are serrated and the large end cap 4 is connected and fixed to the large end body 3 by the rod bolt 5 via the crank pin. The fitting surfaces 3b and 3b ′ and the mounting surfaces 4b and 4b ′ are configured so as not to shift. Further, the split surface that divides the large end portion 7 into the large end portion main body 3 and the large end portion cap 4 is obliquely divided. That is, the mounting surfaces 3b and 3b ′ and the center line of the rod portion 1 (a line connecting the center of the mounting through-circular portion 2a of the small end portion 2 and the arc center of the mounting portion 3a of the large end body 3). The formed angle A is smaller than 90 degrees, which facilitates the removal of the large end cap 4 when performing maintenance from the side cover of the engine.
[0012]
Then, the mounting and fixing of the large end cap 4 to the large end body 3 when the crank pin is attached to the large end 7 of the connecting rod is performed as follows. That is, the mounting surfaces 3b and 3b 'of the large end body 3 and the mounting surfaces 4b and 4b' of the large end cap 4 are joined to each other, and the rod is viewed from the shoulder 4e and 4e 'side of the large end cap 4. The bolts 5 and 5 are inserted through the washers 6 and 6, and the screw portions 5a of the rod bolts 5 and 5 are screwed into the female screw portions 3d and 3d 'of the large-end portion main body 3, so that the large-end portion main body 3 is inserted. The large end cap 4 is attached and fixed.
[0013]
In the connecting rod configured as described above, the shaft center of the rod bolt 5 inserted into the mounting surface 3b side of the large end body 3 and the mounting surface 4b side of the large end cap 4 is The tip of the rod bolt 5 is inclined in a direction toward the outer edge of the large end main body 3 with respect to the perpendicular of the mounting surfaces 3 b and 3 b ′ and the mounting surfaces 4 b and 4 b ′ of the large end cap 4. In FIGS. 1 and 2, the tip end of the rod bolt 5 is inclined only in the direction of the attachment surfaces 3 b and 4 b toward the outer edge of the large end body 3 .
[0014]
That is, the inclination angle θ formed by the mounting surfaces 3b and 3b ′ and the mounting surfaces 4b and 4b ′ and the axis of the rod bolt 5 is configured to be larger than 90 degrees. This inclination angle θ determines an optimum value depending on the material, size and shape of the connecting rod and rod bolt 5 and the shape of the serration. If a predetermined value is appropriately adopted for each connecting rod, Although it is not particularly limited, 90 ° <θ <95 ° is preferable.
[0015]
By configuring as described above, the axial force acting center line of the rod bolt 5 is brought close to the outer end portion of the mounting surface 3b serving as a mouth opening action point, thereby increasing the surface pressure of the mouth opening portion. It is possible to increase the opening safety factor and improve the reliability durability of the connecting rod. Here, the opening safety factor is expressed by the opening safety factor = (the lowest surface pressure of the partial surface pressures in the entire joint surface of the mounting surfaces 3b and 4b) / (1 kg / cm @ 2). As this value increases, the reliability durability of the connecting rod increases.
[0016]
FIG. 3 shows the relationship between the inclination angle θ of the rod bolt 5 with respect to the connecting rod split surface and the opening safety factor, and the opening safety factor increases as the inclination angle θ becomes larger than 90 degrees. . That is, if the axis of the rod bolt 5 is tilted with respect to the perpendicular of the mating surfaces of the mounting surfaces 3b and 3b 'and the mounting surfaces 4b and 4b', the opening safety factor is increased and the reliability of the connecting rod is improved. To do.
[0017]
In this way, by increasing the axial center of the rod bolt 5 with respect to the perpendicular of the split surface of the large end 7, the surface pressure of the opening portion is increased while maintaining the same axial force and the same shape as the conventional one. With this, the opening safety rate can be increased and the reliability and durability of the connecting rod can be improved.
[0018]
【The invention's effect】
Since the present invention is configured as described above, the following effects can be obtained.
The split surface that divides the large end portion (7) into the large end portion main body (3) and the large end portion cap (4) has an obliquely divided two-part structure, and the split surface of the large end portion main body (3); The angle (A) formed by the line connecting the arc center of the small end portion (2) of the rod portion (1) and the arc center of the large end body (3) is configured to be smaller than 90 degrees, Two rod bolts inserted into the connecting rod (3b, 3b ′) side of the large end body (3) and the mounting surface (4b, 4b ′) side of the large end cap (4) of the connecting rod ( 5 and 5) , only the rod bolt (5) on the mounting surface (3b) and mounting surface (4b) side of the rod bolt (5) is connected to the tip end of the rod bolt (5). The mounting surfaces (3b, 3b ') and the mounting surfaces (4b, 4b') and the axis of the rod bolt (5) are tilted in the direction toward the outer edge of the rod bolt (5). Since the inclination angle (θ) to be formed is 90 ° <θ <95 °, the axial force acting center line of the rod bolt 5 is set in the direction of the outer end portion of the mounting surface 3b serving as the opening opening acting point. However, by increasing the surface pressure of the mouth opening as close as possible, the mouth opening safety factor can be increased and the reliability durability of the connecting rod can be improved. FIG. 3 shows the relationship between the inclination angle θ of the rod bolt 5 with respect to the connecting rod split surface and the opening safety factor, and the opening safety factor increases as the inclination angle θ becomes larger than 90 degrees. . That is, if the axis of the rod bolt 5 is tilted with respect to the perpendicular of the mating surfaces of the mounting surfaces 3b and 3b 'and the mounting surfaces 4b and 4b', the opening safety factor is increased and the reliability of the connecting rod is improved. To do. By configuring as described above, while maintaining the same axial force and the same shape as the conventional one, it is possible to increase the mouth opening safety factor by increasing the surface pressure of the mouth opening part and improve the reliability durability of the connecting rod. did it. Moreover, since only one side is inclined, processing is simple.
[Brief description of the drawings]
FIG. 1 is an overall front view showing a connecting rod of the present invention.
FIG. 2 is a partial cross-sectional view showing a fastening portion by a rod bolt between a large end body and a large end cap.
FIG. 3 is a graph showing the relationship between the inclination angle θ of the rod bolt with respect to the connecting rod split surface and the opening safety factor.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Rod part 2 Small end part 3 Large end main part 3b * 3b 'Mounting surface 3c * 3c' Fixing hole 4 Large end cap 4b * 4b 'Mounting plane 4c * 4c' Fixing hole 5 Rod bolt 7 Large end part

Claims (1)

The split surface that divides the large end portion (7) into the large end portion main body (3) and the large end portion cap (4) has an obliquely divided two-part structure, and the split surface of the large end portion main body (3); The angle (A) formed by the line connecting the arc center of the small end portion (2) of the rod portion (1) and the arc center of the large end body (3) is configured to be smaller than 90 degrees, Two rod bolts inserted into the connecting rod (3b, 3b ′) side of the large end body (3) and the mounting surface (4b, 4b ′) side of the large end cap (4) of the connecting rod ( 5 and 5) , only the rod bolt (5) on the mounting surface (3b) and mounting surface (4b) side of the rod bolt (5) is connected to the tip end of the rod bolt (5). The mounting surfaces (3b, 3b ′) and the mounting surfaces (4b, 4b ′) and the axis of the rod bolt (5) are tilted in the direction toward the outer edge of the rod bolt (5). A connecting rod characterized in that an inclination angle (θ) to be formed is 90 ° <θ <95 ° .

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