JPS6047848A - Piston - Google Patents

Abstract

PURPOSE:To prevent the generation of non-uniform strain on the circumferential section of the piston and contrive to facilitate the manufacture and reduce the cost of the piston by a method wherein the main body of the piston is formed by the forming work of a metallic plate and the boss section for a piston pin is attached to the top section of the piston. CONSTITUTION:The main body 1 of the piston, consisting of the top section 1a and the circumferential section 1b, are formed by the forming work or press forming, for example, of the metallic plate. The boss sections 8, 9 for the piston pin are attached to the rear surface of the top section 1a of the piston. Respective bosses 8, 9 are bored with holes 11 for inserting the piston pin 10 while the piston pin 10 is pivotably connected to a connecting rod 18 through bearings. According to this method, a structure, in which no force is applied from the boss sections 8, 9 to the circumferential section 1b of the piston, may be obtained and the ununiform thermal stress will never be applied to the circumferential section 1b of the piston by the existence of the boss sections 8, 9.

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD The present invention relates to a piston structure formed by molding a metal plate, and also relates to a related cooling structure around piston rings and at the top of the piston.

BACKGROUND OF THE INVENTION Pistons for internal combustion engines for passenger cars have conventionally been made of cast or forged materials such as cast iron or aluminum. However, casting or forging screws have the same problems as conventional methods.

First of all, casting and forging have a lot of excess material, which hinders the reduction in weight of internal combustion engines and vehicle agitation.

In addition, since the piston pin boss is connected to the circumference of the screw, if combustion gas pressure or inertial force is applied to the screw 1 boss, the entire piston will deform and become distorted. In addition, since the heat flow is biased toward the screw 1 hembin boss, a difference in thermal expansion occurs, which may cause uneven distortion of the piston circumference.In order to deal with these unrestricted distortions, the piston circumference is usually The piston has a barrel shape in the axial direction and an elliptical shape in the radial direction, which complicates the manufacture of the piston.

Purpose of the Invention In order to eliminate or reduce the above-mentioned problems, the present invention has a structure in which no force is applied from the piston pin boss to the piston circumference, and the presence of the screw boss prevents unevenness on the piston circumference. The purpose of the present invention is to provide a piston with a structure that does not cause thermal distortion.

Structure and operation of the invention In order to achieve this object, in the piston of the present invention, the piston body consisting of the piston top and the piston circumference is formed by molding a metal plate, and is made of a metal plate. A piston pin boss part is joined to the back surface of the top of the piston.

In such a piston, the combustion gas pressure is transmitted directly from the top of the piston to the piston pin boss and then to the connecting rod, and no load is applied to the circumference of the piston, so the circumference of the piston receives the explosive force of combustion. [There is no chance of distortion. Also, the piston pin boss part is screw 1.
Since it is not attached to the circumferential portion of the piston, distortion of the circumferential portion of the piston due to uneven thermal expansion is also suppressed.

EXAMPLES Below, preferred examples of the piston of the present invention will be described with reference to the drawings.

1 to 3 show a piston according to a first embodiment of the invention. In the figure, 1 is a piston main body, which is composed of a piston top portion 1a and a piston circumferential portion 1b. The piston body 1 is formed by forming a metal plate, for example, by press forming.

Therefore, the piston body 1 is made of a bottomed cylindrical body that is thinner than the conventional piston top portion 1a and the piston circumferential portion 1b and has approximately the same thickness.

A piston ring groove 2.3 is formed in an annular shape on the outer peripheral surface of the piston body 1 near the top, and an oil ring groove 4 is formed in an annular shape on the outer peripheral surface of the piston body 1 below the piston ring groove 2.3. 7 is inserted. These piston ring grooves 2.3 and oil ring grooves 4
may be processed by machining or the like after the piston body 1 is molded.

A piston pin boss portion 8.9 is provided on the back surface of the piston top portion 1a.
are joined. The screw boss portion 8.9 is not joined to the screw circumferential portion 1b.

This joining is done by welding 1 such as laser welding or electron beam welding.
4. Bonded using means and methods that minimize distortion.

A hole through which the piston pin 10 is inserted is formed in the piston pin boss portion 8.9, and this hole is machined to penetrate from the outer periphery of the piston body 1. And in this hole, piston pin 1
0 is inserted. A hole 11 is also made in the piston body 1 for machining the piston pin hole. The piston pin 10 is swingably connected to a connecting rod 18 via a bearing.

By installing the piston pin boss portion 8.9 on the piston top portion 1a, the piston circumferential portion 1b does not have to consider the influence of the piston pin boss portion 8.9, and therefore the piston circumferential portion 11) is It can be manufactured into a perfectly circular cylindrical body, and in this example, the cross section is formed to be perfectly circular.

Next, the operation of the piston of the first embodiment will be explained.

First, since the entire piston body 1 is made of a metal plate, it can be made thinner and lighter. Although pistons in which part of the piston is made of metal plates have been proposed in the past (for example, Utility Model Application No. 57-137752), as in the present invention, both the piston top 1a and the piston circumference 1b are made of metal. There is no one made of board. By making it made of metal plate, excess internal sag is removed, resulting in a significant weight reduction, contributing to improved barrier performance and fuel efficiency. Further, by using a pressed metal plate structure, the manufacturing process can be simplified and costs can be reduced.

The combustion gas pressure is transmitted directly from the piston top 1a to the piston pin 10 via the piston pin boss 8.9, so no load is applied to the piston circumference 1b, and the distortion of the piston circumference 1b is minimal. be converted into Further, since the piston pin boss portion 8.9 is not attached to the piston circumferential portion 1b, the thermal expansion in the piston circumferential portion 11) is made uniform, and thermal strain is small. Under these conditions, as described above, the piston circumferential portion 1b can be processed to have a perfect circle in cross section.

Machining costs for perfect circles are significantly lower than traditional barrel machining.

In addition, due to the small thermal strain and uniform expansion, the clearance between the outer circumferential surface of the cylinder and the cylinder bore can be made small, and the blow-by gas color and exhaust emissions, especially HC, can be kept small.

Furthermore, by selecting a material similar to that of the liner for the piston material, it is possible to reduce the difference in thermal expansion between the cylinder and the piston at cold temperatures, reducing slap noise and reducing noise. It is measured.

In addition, by shortening the distance of the piston pin boss portion 8.9, the bending force applied to the piston pin 10 can be reduced, and even if the piston pin 1o is made of a thin cylindrical material, it can maintain its strength. 10(7) Iffi conversion can also be achieved.

This in turn leads to improved locking performance and weight reduction.

4 and 5 show a piston according to a second embodiment of the invention. In d3 of this embodiment, an oil reservoir 12 is formed on the back side of the piston top 1a. An oil reservoir bottom plate 13 is disposed on the back side of the piston top portion 1a with a gap from the back surface of the piston top portion 1a.
is fixed to the piston pin boss portion 8.9 by means such as welding 14 or screws. Therefore, no R effect is exerted on the piston circumferential portion 1b.

The oil reservoir bottom plate 13 is inclined upward toward the outer periphery, making it difficult for oil to accumulate in the center. An oil hole 15 is bored near the outer periphery of the oil reservoir bottom plate 13, through which oil from the oil jet does not pass. Further, a gap 16 is partially provided in the joint surface of the piston bin boss portion 8.9 to the piston body 1, and serves as a relief hole for cooling oil. By forming the gap 16, it is also possible to equalize the load of the combustion gas pressure transmitted from the piston body 1 to the piston bin boss portion 8.9. Since the other configurations are similar to those of the first embodiment, corresponding parts are given the same reference numerals as those of the first embodiment.

The piston of the second embodiment configured as described above has the first
In addition to the above-described effects of the embodiment, the present invention has the following effects.

That is, oil jetted upward from the oil jet passes through the oil hole 15 and enters the oil reservoir 12. The oil entering the oil reservoir 12 bounces between the oil reservoir bottom plate 13 and the back surface of the piston top 1a due to the vertical movement of the piston, thereby effectively cooling the top 1a of the piston. Therefore, the humidity on the top surface of the piston that defines the combustion seedlings decreases, and knocking is suppressed. Suppressing knocking enables higher compression ratios and improves fuel efficiency.

FIG. 6 shows a piston according to a third embodiment of the invention. In this embodiment, the top land portion 1C of the piston body 1 is connected to other piston body portions. By adopting such a joining structure,
It is possible to employ a piston ring 5- with no cut in the screw 1 ring fitted into the uppermost piston ring groove 2, that is, the first piston ring groove 2. The continuous piston ring 5- is made of a hollow pipe-shaped annular screw ring in order to provide some elasticity in the radial direction, for example. The top land portion 1C is joined by welding 17, such as laser welding or electron beam welding, which locally suppresses thermal distortion, and the outer periphery is processed later if necessary. The other configurations are similar to the first embodiment or the second embodiment.

The piston of the third embodiment has the following functions in addition to the functions of the piston of the first or second embodiment. In other words, with a seamless piston ring 5-, there is no phenomenon in which the abutment between the upper and lower piston rings 5.6 aligns in the vertical direction, so combustion gas and oil can flow through the abutment between the combustion chamber and the lower part of the piston. Mutual leakage between the space and the space is prevented, thereby reducing blow-by gas and oil consumption. Furthermore, since leakage of combustion gas is suppressed, the effective compression pressure is also increased, which naturally improves engine performance. Incidentally, such a continuous annular piston ring 5'' structure can be easily adopted in the piston of the present invention in which the piston body 1 has the piston circumferential portion 1b having a perfectly circular cross section.

Effects of the Invention As is clear from the above explanation, the piston of the present invention has the following effects:
Since the piston body is formed by molding a metal plate and a screw boss is attached to the top of the piston, the present invention prevents uneven distortion in the piston circumference due to combustion gas pressure and thermal expansion difference. It is possible to prevent this from occurring, and by machining the circumference of the piston into a perfect circle, manufacturing can be facilitated and costs can be reduced.
The benefits include light weight, improved fuel efficiency, reduced exhaust emissions, and reduced noise.

In addition, by supporting the oil reservoir bottom plate with a screw 1 hembin boss and installing an oil reservoir on the back side of the piston top, it is possible to reduce the humidity on the top surface of the piston without causing any adverse thermal effects on the piston circumference, thereby preventing knocking. The secondary effect of improving fuel efficiency through the suppression of
'□7 will be received.

Furthermore, if the top land of the piston is joined (i! 3 blue), a seamless piston ring can be used as the first piston ring, reducing blow-by gas, reducing oil consumption, and increasing effective compression pressure. You can get the side effect of being able to do it.

[Brief explanation of drawings]

FIG. 1 is a front view showing the left half of the piston according to the first embodiment of the present invention in cross section, FIG. 2 is a sectional view of the piston in FIG. 1, FIG. 4 is a sectional view of a portion of the piston according to the second embodiment of the present invention corresponding to FIG. 2, FIG. 5 is a bottom view of the piston in FIG. 4, and FIG. 6 is a bottom view of the piston in FIG. FIG. 3 is a partial cross-sectional view of the vicinity of the piston top land portion of a piston according to a third embodiment of the present invention. 1...Piston body 1a...Piston top 1b...Piston circumferential part 1C...1-Twin brand part 2...1st Piston ring vortex 3... Piston ring groove 4... Oil ring groove 5... First piston ring 6... Piston ring 7... Oil ring 8.9...Piston pin boss part 10...
・Piston bin 11... Hole 12... Oil reservoir 13... Oil reservoir bottom plate 14... Welding 15... Oil hole 16... ...Gap 17...Welding Fig. 4＼ 0 Fig. 6

Claims (4)

[Claims] (1) A piston characterized in that a screw 1 hen main body consisting of a screw 1 hen top and a piston circumference is formed by molding a metal plate, and a piston pin boss is joined to the piston top. (2) The piston according to claim 1, wherein the piston circumferential portion is formed into a perfect circle. (3) The piston according to claim 1, wherein an oil reservoir bottom plate is disposed on the back side of the top of the piston with a gap from the back surface of the piston top, and the oil reservoir bottom plate is supported by the piston screw boss. . (4) The screw according to claim 0, wherein the top land portion of the piston body has a joining structure, and the top land portion is joined after a continuous annular piston ring is assembled into the M1 piston ring groove. 1 hen.