JPS6237218B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION FIELD OF INDUSTRIAL APPLICATION The present invention relates to a piston for an internal combustion engine.

BACKGROUND OF THE INVENTION A conventional piston used in an internal combustion engine has a piston head, a piston pin bore, and a skirt extending around the entire circumference of the piston. In this case, the skirt does not function to seal the gas, but the piston ring attached to the piston works to seal the gas. On the contrary, the skirt has the disadvantage of transmitting the lateral forces exerted on the piston by the connecting rod during the reciprocating movement of the piston to the corresponding cylinder or liner.

Although the weight of the above-mentioned pistons has certainly been reduced in recent years by the use of aluminum or aluminum alloys, the above-mentioned pistons are still quite heavy, and the area of the skirt in contact with the cylinder or liner is less likely to be affected by internal combustion. This creates considerable frictional forces that must be overcome by the engine and thus reduce the power output of the internal combustion engine. Various proposals have already been made with the aim of reducing such skirt range; however, these proposals have generally not been commercially successful due to lubrication problems and skirt stiffness.

OBJECTS OF THE INVENTION Therefore, an object of the present invention is to significantly reduce the weight of the skirt area compared to conventional ones;
Moreover, the aim is to provide a piston in which the skirt region has sufficient rigidity and is also satisfactory in terms of lubrication.

Means for Solving the Problem In order to solve this problem, the configuration of the present invention includes:
A piston for an internal combustion engine having a piston head, a pair of piston pin holes, and a pair of piston pin bosses is provided with a support reinforced by a flange, the support being aligned with the axis of the piston pin hole. The supports extend perpendicularly from each piston pin boss toward both sides of the piston on sides facing each other across a plane containing the piston axis and the piston pin hole axis; The piston has ends on its sides and is provided with first and second bearing surfaces acting as skirts on each side of the piston, the bearing surfaces extending over only a portion of the circumference of the piston. A first supporting surface provided on each side of the piston is located at the lower end of the piston head, and the lower edge of the first supporting surface forms the entire supporting surface of the piston. is located in a plane perpendicular to the piston axis, and a second support surface, provided on each side of the piston, extends from the associated end of the support and is supported by the support. the upper and lower edges of the second supporting surface each extend in the circumferential direction from the end of the associated support in planes perpendicular to the piston axis and parallel to each other; the plane in which the lower edge of the first support surface is located is spaced apart in the axial direction from the plane in which the upper edge of the second support surface is located; In between, a large axially and circumferentially extending gap is formed which guides the lubricating oil to the corresponding cylinder wall.

Effects of the Invention With the structure of the present invention, the support surface acting as a skirt is composed of two support surfaces each extending over only a portion of the entire circumference of the piston. The range and thus the overall weight of the piston is significantly reduced compared to the conventional one. Moreover, in this case the first support surface is arranged at the lower end of the piston head, and
Because the second support surface extends from the piston pin hub and is supported by a flange-reinforced support, the support surface has sufficient strength.

In addition, a large amount of lubricating oil is supplied from inside the piston to the cylinder or liner through the large gap located between both supporting surfaces when viewed in the piston axial direction, so there is always sufficient lubricating oil between the supporting surface and the cylinder during the movement of the piston. A good lubricating oil film is present, thus ensuring that direct contact between the bearing surface and the cylinder, i.e. metal-to-metal contact, and thus also jamming of the piston is avoided.

Example Next, embodiments of the present invention will be described with reference to the drawings.

As shown in FIGS. 1, 2 and 4, the piston 1 includes a piston head 2 surrounded by a piston land 3 for receiving a piston ring (not shown), and a piston head 2 surrounded by a piston land 3 for receiving a piston ring (not shown). It has a pair of piston pin bosses 6 forming a piston pin hole (see FIG. 2) into which a pin (not shown) is inserted.

Furthermore, the piston 1 has two supporting surfaces 4 and 5 on both sides of a plane including the piston pin hole axis and the piston axis, and both supporting surfaces 4 and 5, which act as skirts, extend in the axial direction and the circumferential direction. They are separated by a large gap. An upper bearing surface 4 located at the lower end of the piston head 2 extends downwardly from the piston land 3 (see FIG. 2), while the other lower bearing surface 5 is located on a mating support. 7 (which may have the shape shown in FIGS. 7A and 7B) is connected to the piston pin boss 6. The lower support surface 5 is therefore only supported in a cantilevered manner by the support 7 extending from the piston pin boss 6. The supporting surfaces 4, 5 are arranged symmetrically near a plane (i.e., the cross section in FIG. 2) containing the piston axis and a line perpendicular to the piston pin hole axis, and are located only on the circumferential surface of the piston 1. It is only partially extended. For example, the bearing surfaces 4, 5 extend over 45° on either side of said plane.

In another embodiment (not shown), the support 7 may carry not only the lower bearing surface 5 but also the upper bearing surface 4.

The bearing surfaces 4, 5 have approximately the shape of a cylindrical segment, the lower edge of the upper bearing surface 4 and the two circumferentially extending edges of the lower bearing surface 5 being relative to the piston axis. They are located in planes that are perpendicular and parallel to each other, and chamfers 8 are provided on their edges.

The advantageous shape of the lower support surface 5 and the associated chamfer 8 is shown enlarged in FIG. The bearing surface 5 is curved in the plane containing the piston axis and has a maximum radial depth (see x in FIG. 6) of, for example, 0.02 mm. Chamfered part 8
is flat in the plane containing the piston axis,
In this case, the length of the chamfered portion 8 is 1 mm and the chamfered portion 8 is inclined at an angle of 15° with respect to the vertical direction, or the length of the chamfered portion 8 is 1 mm and the radial depth (the sixth
(see y in the figure) is 0.04mm. However, it is also possible for the double-sided bevel 8 to be curved and for the bevel 8 and the support surface 5 to have another corresponding shape. It is also possible for the chamfer 8 on the lower edge of the upper support surface 4 to have dimensions equal to the advantageous shape described above.

In use, lateral forces on the piston are transferred to the corresponding cylinder or liner 20 by the support surfaces 4,5.
transmitted to. The fact that the chamfer 8 forms a passage leading to the associated bearing surface and reducing its dimensions ensures a sufficient supply of lubricating oil to the bearing surfaces 4, 5 during the reciprocating movement of the piston, so that The lubricating oil reaches the bearing surfaces 4, 5 under pressure, thus ensuring sufficient hydrodynamic lubrication. With the lower bearing surface 5 being curved as shown in FIG. 6, the curvature of this bearing surface 5 also serves to ensure sufficient lubrication. The reduction in the dimensions of the bearing surfaces 4, 5 and the windows thereby formed in the skirt reduce the weight of the piston, which is responsible for the reduction in power. Furthermore, frictional losses due to contact between the piston and the corresponding cylinder or liner are reduced due to the fact that the extent of the bearing surfaces 4, 5 is small compared to conventional pistons with a continuous skirt. I am forced to do it. The bearing surfaces 4, 5 are sufficiently lubricated so that the bearing surfaces 4, 5 can be
The gap can always be kept at a maximum. Furthermore, due to the dimensions of the bearing surfaces 4, 5, the manufacturing costs of the piston are reduced and the performance of the engine in which it is installed is also improved.

The piston of the second embodiment shown in FIGS. 3 and 5 is substantially the same as the piston of the first embodiment shown in FIGS. 1, 2, and 4; Components common to the piston have the same reference numerals plus an a. Further, detailed explanation of common parts will be omitted here. In the second embodiment shown in FIGS. 3 and 5, instead of the bearing surface 5 remote from the piston head 2, the bearing surface 9 is spaced apart in the circumferential direction and is approximately rectangular in the form of a sector. One pair of each is provided. Each support surface 9 of each support surface pair is connected via a support 7a (which may have the shape shown in FIGS. 7A and 7B) to the associated piston pin boss 6a. The support surface 9 has a chamfer similar to the support surface 5 and may have cross-sectional dimensions as described above with reference to FIG. The bearing surface 9 is axially aligned with the upper bearing surface.

A metal ring 10, shown in broken lines in FIGS. 3 and 5, connects the four sector-shaped support surfaces 9 to one another and serves to control the extent of the support surfaces 9 in the radial direction.

The piston according to the second embodiment operates in substantially the same manner as the piston according to the first embodiment and has substantially the same advantages. However, because the sector-shaped support surface 9 has a smaller area than the support surface 5, both weight and friction are further advantageously reduced.

Further, an embodiment in which three or more supporting surfaces are provided on both sides of a plane including the piston axis and the piston pin hole axis is also possible. It is also possible to provide three or more bearing surfaces on each side, for example in the manner shown in FIGS. 3 and 5.

[Brief explanation of the drawing]

FIG. 1 is a side view showing a first embodiment of a piston according to the present invention, FIG. 2 is a sectional view taken along the line - - in FIG. 1, and FIG. 3 is a side view showing a second embodiment of a piston according to the present invention. 4 is a bottom view of the piston shown in FIGS. 1 and 2, and FIG. 5 is a view of the piston shown in FIGS.
FIG. 6 is a sectional view taken along the line - in FIG. 1 or 3, and FIGS. 7A and 7B are sectional views showing the cross-sectional shape of the support body. It is. 1... Piston, 2, 2a... Piston head, 3, 3a... Piston land, 4, 5, 9...
...Supporting surface, 6, 6a...Piston pin boss, 7,
7a...Support, 8...Chamfer, 10...Metal ring, 20...Liner, x...Maximum radial depth of support surface curvature, y...Radial depth of chamfer.

Claims (1)

[Claims] 1. A piston head, a pair of piston pin holes, and 1.
A piston for an internal combustion engine having a pair of piston pin bosses, the support being reinforced by a flange, the support extending from each piston pin boss perpendicularly to the axis of the piston pin hole. , extending toward both side surfaces of the piston on opposite sides of a plane containing the piston axis and the piston hole axis, each support having an end on the side surface of the piston, First and second support surfaces are provided on each side of the piston, each serving as a skirt, and the support surfaces extend over only a portion of the circumference of the piston and cover the entire support surface of the piston. The first support surfaces provided on both sides of the piston are located at the lower end of the piston head, and the lower edge of the first support surface is located at a point perpendicular to the piston axis. a second support surface located in a plane and provided on each side of the piston extends from the associated end of the support;
The second support surface is supported exclusively by the support, and the upper and lower edges of the second support surface each extend circumferentially from the end of the associated support and are perpendicular to the piston axis. and are located on planes parallel to each other, and the plane on which the lower edge of the first support surface is located is the second plane.
The upper edge of the supporting surface of the cylinder is located at an interval in the axial direction from the plane in which the upper edge of the support surface is located, and a gap is formed between the two planes that extends in the axial and circumferential directions to guide lubricating oil to the corresponding cylinder wall. A piston for internal combustion engines that is characterized by: 2. At least one of the edges of the second support surface is provided with a chamfered portion for guiding lubricating oil to the second support surface during reciprocating movement of the piston.
A piston according to claim 1. 3. The piston according to claim 2, wherein the chamfer is flat or curved in a plane containing the piston axis. 4. Claims in which the second support surface is barrel-shaped and curved in a plane containing the piston axis in order to guide lubricating oil to the second support surface during reciprocating movement of the piston. The piston according to item 2 or 3. 5. The support according to any one of claims 1 to 4, wherein the support has a T-shaped or cross-shaped cross section and is cast integrally with the other parts of the piston. piston.