JPH04244671A - Piston for internal combuation engine - Google Patents

Abstract

PURPOSE:To reduce the extent of friction between a skirt and a cylinder or liner without entailing any damage to rigidity of a skirt part. CONSTITUTION:A pin boss 4 is installed in the central part of the back 3 of a piston top face. A skirt 5 is installed as halved in both thrust and opposite directions. In the skirt 5, its upper part 5a is broad as extending in the circumferential direction, and the lower part 5b is formed into a T-shaped from extended downward. Moreover, this skirt 5 is supported by a supporter 8 which connects the pin boss 4 and the skirt 5.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piston for an internal combustion engine that has reduced friction in its skirt portion.

0002

2. Description of the Related Art The skirt portion of a piston supports the thrust force generated by combustion pressure, inertia force, rod ratio, and the like.

However, the contact of the skirt with the cylinder or liner is a source of high frictional losses.

[0004] Therefore, by reducing friction,
It is possible to increase output and also reduce fuel consumption. For this reason, pistons in which the frictional force of the skirt portion is reduced have been proposed.

[0005] As a conventional piston for such an internal combustion engine, for example, there is a piston as shown in FIG.
8-38357, etc.).

That is, the plate-like raised portions 15 are separately provided in the contact area with the cylinder or liner (not shown) of the skirt 5, and are divided into two similar groups of three each. This reduces the contact area with the material and reduces friction loss.

[0007]

However, in such a conventional piston for an internal combustion engine, the shape of the skirt portion 5 is complicated, and in order to form the raised portion 15,
There is a problem in that it is necessary to introduce a three-dimensional NC device, which increases the cost.

[0008] Furthermore, since the lubricating oil is dragged by the raised portions 15, there is a problem that the friction may increase instead.

The present invention has been made in view of these conventional problems, and it is an object of the present invention to provide a piston for an internal combustion engine that reduces frictional force without complicating the shape of the skirt portion. It is an object.

0010

[Means for Solving the Problems] Therefore, the present invention provides a single pin boss provided at the center of the piston crown surface independently of the piston skirt, and a pin boss provided on the thrust side and anti-thrust side of the piston that extends from the piston crown surface. A T-shaped piston skirt divided into two and a piston skirt support that is substantially perpendicular to the pin boss direction and connects the T-shaped piston skirt and the pin boss are provided.

[0011]

[Operation] Since the skirt is T-shaped, the contact area with the cylinder or liner is small and the surface pressure is constant.

Furthermore, since the skirt is supported by a support connected to the pin boss, it has sufficient rigidity, and the support itself may have a simple shape such as a plate.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained below based on the drawings. 1 to 4 are diagrams showing a first embodiment of the present invention.

First, the configuration will be explained. Crown surface 2 of piston 1
A single pin boss 4 is formed on the back surface 3 of the skirt 5, independently of the skirt 5, and protruding downward from the center thereof.

As shown in FIG. 3, the upper part 5a of the skirt 5 is wider than the lower part 5b in the circumferential direction, and the upper part 5a includes the piston pin axis 7, and the lower part 5b extends downward and has a T-shape. It becomes.

The T-shaped skirt 5 is arranged on both sides (the thrust direction and the anti-thrust direction) of a plane including the piston axis 6 and the piston pin axis 7.

Further, the skirt 5 and the pin boss 4 are supported by a support body 8 extending from the pin boss 4 in the thrust direction and the anti-thrust direction of the piston 1.

As shown in FIG. 4, the piston 1 is constructed by press-fitting the bifurcated small ends 11 of the connecting rod 9 into both ends of the piston pin 10, which is disposed through the pin boss 4. is combined with

Next, the operation will be explained. piston skirt 5
calculates the maximum thrust force under all engine operating conditions and has an area determined by its value and the allowable contact pressure of the piston material. Further, in general, the input to the skirt portion above the piston pin axis 7 is greater than the input below. Furthermore, the support of the so-called neck swing of the piston 1 is naturally more effective as it moves downward.

Also, during reciprocating movement of the piston, the conventionally shaped skirt does not have its entire outer circumference in contact with the cylinder or liner. Although the exact shape of the contact area varies from piston to piston, the contact area is generally confined to the vicinity of either side of the thrust face-skirt intersection line.

[0021] Taking these into consideration, the present invention has developed a skirt 5.
In order to reduce the area to the minimum required area and to keep the contact surface pressure constant, the upper part 5a that receives a large force is wide in the circumference, and the lower part 5b to suppress neck swing is extended downward to form a T-shape. It has become.

On the other hand, if the skirt 5 is formed into such a T-shape, the rigidity of the skirt lower part 5b will be weakened, and this portion will not be able to support the thrust force.

Therefore, a support 8 is provided extending from the pin boss 4 in the thrust direction and the anti-thrust direction to connect the pin boss 4 and the skirt 5.

[0024] As described above, since the support body 8 extends from the pin boss 4 having high rigidity, the support body 8 itself does not require much rigidity. Therefore, it can be made into a simple shape such as a plate or a rod.

With the structure described above, according to this embodiment, the skirt 5 has the minimum necessary area, so that the frictional force between the skirt 5 and the cylinder or liner (not shown) can be reduced. Can be made smaller. Moreover, the weight of the piston 1 can also be reduced.

[0026] Since the support body 8 may have a simple shape, the support body 8
The weight increase due to the installation is small. Further, since the skirt is T-shaped, the swinging of the piston 1 can be effectively suppressed.

FIG. 5 shows a second embodiment of the present invention. In this embodiment, a plurality of (two in the figure) supports 12a and 12b extend from the pin boss 4 in the thrust direction and the anti-thrust direction of the piston 1 to connect the pin boss 4 and the T-shaped skirt 5. Thus, the skirt 5 is supported.

According to this embodiment, the supports 12a, 12b
Since a plurality of are provided, the skirt 5 can be supported with higher rigidity. Further, since the rigidity of the supports 12a, 12b itself does not need to be large,
The weight increase due to 2b may be small.

FIG. 6 shows a third embodiment of the present invention. In this embodiment, a hole 1 is provided in the support 13 in the axial direction of the piston pin.
4 is opened, and the lower part 5b of the T-shaped skirt 5 is supported by the support body 13.

According to this embodiment, it is possible to effectively support the skirt lower part 5b, which poses a problem in terms of rigidity, and
The weight of the support body 13 can be further reduced.

[0031]

As explained above, according to the present invention, since the skirt is T-shaped and has the minimum necessary area, the frictional force of the skirt portion can be reduced, and
The weight of the piston can be reduced. Furthermore, since the pin boss and the skirt are connected with the support body to support the skirt, the skirt can be effectively supported, and a support body with a simple shape can be used.

[Brief explanation of the drawing]

FIG. 1 is a plan view of the back of the crown surface of a piston, looking up from below, showing a first embodiment of the present invention.

FIG. 2 is a side view of a piston seen from the piston pin axial direction, also showing the first embodiment.

FIG. 3 is a side view of a piston seen from a direction perpendicular to the piston pin axis, also showing the first embodiment.

FIG. 4 is a sectional view showing a state of connection with a connecting rod, also showing the first embodiment.

FIG. 5 is a plan view of the back of the piston crown surface showing a second embodiment of the present invention.

FIG. 6 is a side view of a piston showing a third embodiment of the present invention.

FIG. 7 is a side view showing a conventional example.

[Explanation of symbols]

3...Behind the crown surface 4...Pin boss 5...Skirt 7...Piston pin axis 8...Support 12a, 12b...Support 13...Support 14...hole

Claims (1)

[Claims] Claim 1: One pin boss provided at the center of the piston crown surface independently of the piston skirt, and a T which extends from the piston crown surface and is divided into two parts, the thrust side and the anti-thrust side of the piston.
The piston skirt is approximately perpendicular to the direction of the pin boss,
A piston for an internal combustion engine, comprising a T-shaped piston skirt and a piston skirt support that connects a pin boss.