JPH0322534Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a piston for an internal combustion engine, and particularly to a piston used in an internal combustion engine equipped with an oil injection type piston cooling device.

[Prior Art] As the output of internal combustion engines increases, the top wall of the piston, which is located inside the cylinder bore and forms part of the wall of the combustion chamber, is exposed to a severe thermal load and requires forced cooling. It's coming.

As a piston cooling device that forcibly cools the top wall of the piston, engine lubricating oil is injected from the inner space of the piston body having a cup-like structure toward the top wall of the piston, and the engine lubricating oil cools the piston. An oil injection piston cooling device that cools the top wall has already been proposed, and in order to more effectively cool the piston top wall with such an oil injection piston cooling device, a In order to temporarily catch the injected lubricating oil and spray it again toward the top wall of the piston as the piston reciprocates,
It is known in Japanese Utility Model Publication No. 54-26424 and the earlier Utility Model Application No. 1983-1983 to install a shelf-shaped oil reservoir member forming an oil reservoir in the inner space of the piston body, facing the inner surface of the top wall of the piston. No. 185184 (Actual Publication No. 18518-
90055).

As described above, by inserting the shelf plate-shaped oil reservoir constituent member into the inner space of the piston body and configuring the oil reservoir facing the top wall of the piston body, the oil injection device can spray the top wall of the piston body The lubricating oil injected toward the inner surface of the top wall is received by the oil reservoir after once cooling the top wall, and when the piston reaches its top dead center again, the inertial force acting on the oil pushes the lubricating oil back to the top of the piston. The lubricating oil is sprayed onto the inner surface of the wall, and by spraying or spraying the lubricating oil again, better cooling of the piston top wall is achieved.

In the above-mentioned Japanese Utility Model Publication No. 54-26424, the oil reservoir is a groove cut into the inner surface of the peripheral wall of the piston body, with a shelf-like member having an oil reservoir recess facing it at both ends. The shelf plate-like member is attached to the piston body by being fitted into the piston body, or the central part of the shelf-like member is sandwiched between the central part of the top wall of the piston body and the end of the connecting rod opposite thereto. is attached to the piston body.

Moreover, in the above-mentioned Utility Model Application No. 57-185184, the oil reservoir constituent members are a shelf plate section disposed facing the back surface of the piston top wall section and a pair of leg sections bent from both side edges of the shelf section. The piston pin connecting the piston and the connecting rod is passed through the hole drilled in the leg portion, so that the piston pin can be attached to the piston body via the piston pin. .

[Problem to be solved by the invention] As the piston reciprocates, a fairly large force acts on the oil reservoir component due to the inertial force acting on its own mass at its top dead center and bottom dead center. In addition, especially at the bottom dead center of the piston, a force due to inertia acting on the oil stored in the oil reservoir is also applied, so the attachment of the oil reservoir component to the piston body must have a sturdy structure. Regarding this point, in the above-mentioned Japanese Utility Model Publication No. 54-26424, both ends of the shelf-shaped oil reservoir component are fitted into grooves cut into the inner peripheral surface of the peripheral wall of the piston body. In this case, it seems that there is a problem in the strength of the attachment of the oil reservoir component to the piston body. In addition, the same publication describes a structure in which a shelf-shaped oil reservoir constituent member is sandwiched at its center between the center of the top wall of the piston body and the end of the connecting rod opposite thereto. Because relative displacement occurs between the top wall of the piston body and the connecting rod as the piston reciprocates, this structure allows the shelf-shaped oil reservoir component to be mounted at a predetermined mounting position relative to the piston body. It appears that it is difficult to maintain this level stably.

As in the above-mentioned Utility Model Application No. 57-185184, the shelf plate portion of the oil reservoir component is supported by a pair of leg portions, and the leg portions are attached to the piston body by a piston pin passed through the hole. Although the structure appears to have sufficient mounting strength, in this case the oil sump component must be installed at the same time as the piston and connecting rod are assembled together.
Assembling the piston pin may be a complicated task that requires alignment of the piston body, connecting rod, and oil reservoir component, and it is difficult to assemble the piston pin each time the piston and connecting rod are disassembled. There is an inconvenience that the oil reservoir components are also disassembled at the same time.

The present invention provides an oil reservoir component that is inserted into the inner space of a cup-shaped piston body and forms an oil reservoir facing the inner surface of the top wall of the piston body. An object of the present invention is to provide a piston for an internal combustion engine that has a structure that can be directly and firmly assembled.

[Means for Solving the Problems] According to the present invention, the problem is solved by the present invention, which includes a top wall portion, a peripheral wall portion, and a pair of boss portions that protrude inwardly facing each other, and a piston pin hole is formed in the boss portions. a piston body having an open space, a shelf plate portion inserted into the inner space of the piston body and providing an oil reservoir recess facing on the inner surface of the top wall portion, and a pair bent from both side edges of the shelf plate portion. an oil reservoir component having leg portions, and the oil reservoir component has an engagement formed by a press-formed cylindrical portion in which the pair of leg portions extend in directions facing each other. The legs engage with a cylindrical engaging part whose diameter is reduced in steps around the inner end of the boss part in the hole, and the legs are opened by the elastic force that causes the pair of leg pieces to open in the direction away from each other. A piston for an internal combustion engine, characterized in that the cylindrical portion of the piece is held in the engaged state with the cylindrical engaging portion of the boss portion, so that the piston is attached to the piston body. achieved.

[Operation of the device] According to the structure of the present invention as described above, the oil reservoir component has an engagement hole formed in the pair of leg portions by a cylindrical portion that is press-formed and overhangs in directions facing each other. is attached to the piston body while being engaged with the cylindrical engaging part whose diameter is reduced in steps around the inner end of the pair of boss parts that provide the piston pin holes in the piston body, so that the oil sump Since the component is rigidly attached to the piston body, and in this case the attachment does not depend on the piston pin in any way, the oil sump component is attached to the piston body before the piston is connected to the connecting rod by the piston pin. Even when the piston pin is removed after assembly and the piston and connecting rod are disassembled, the oil reservoir component remains assembled to the piston body.

[Embodiments] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 to 3 show one embodiment of a piston for an internal combustion engine according to the present invention. The piston for an internal combustion engine according to the present invention is composed of a piston body 1 and an oil reservoir forming member 10.

The piston body 1 is cast into a cup shape having a cylindrical peripheral wall part 2 and a top wall part 3 provided at one end of the peripheral wall and closing the one end. A pair of boss portions 4 are formed on the inside of the peripheral wall portion 2 to bulge out toward the inner space of the piston body 1 so as to face each other.
Piston pin holes 5 are provided in the pair of boss portions 4 on the same axis. A piston pin that connects the piston body 1 to a connecting rod (not shown) is inserted into the piston pin hole 5. Two piston ring grooves 6 are provided on the outer periphery of the top wall 3 and the side wall 2.
and one oil ring groove 7 are provided.
The oil ring groove 7 communicates with the inner space of the piston body 1 via a slit hole 8.

The boss portions 4 each include a cylindrical engaging portion 9a whose diameter is reduced in steps so as to have a smaller diameter than the outer periphery of the root portion on the outer periphery of the tip portion, and an end portion on the root side of the cylindrical engaging portion. It has a stepped portion 9 consisting of an annular end surface 9b.
The piston pin hole 5 on the inner peripheral surface of the piston body 1
Relatively wide grooves 2a are formed along the axis of the piston body 1 from the tip edges of the skirt parts, which face each other in a direction perpendicular to the axis of the piston body.

As shown better in FIGS. 4 and 5, the oil reservoir component 10 includes a substantially rectangular shelf section 12 having an oil reservoir recess 11, and one side from both side edges of the shelf section 12. It has a pair of leg pieces 13 that are bent in a straight line, and a pair of abutment pieces 14 that are bent toward one side from both end edges of the shelf board 12, and the whole is made of a suitable material such as spring steel. It is press-molded from a metal plate with elasticity. The leg sections 13 each include a relatively small first section 13a bent along the first folding line A relative to the shelf section 12, and a first section 1
A relatively large second piece 13 that is bent along the second folding line B relative to 3a and forms the majority of the leg piece 13.
b, and the distance La between the first folding lines A of the pair of leg portions 13 is equal to the tip surface 4 of the pair of boss portions 4.
The distance between a is equal to or slightly smaller than Lb,
Distance Lc between the second folding lines B of the pair of leg pieces 13
is approximately equal to the distance Ld between the annular end surfaces 9b of the stepped portions 9 of the pair of boss portions 4, and the pair of leg portions 13 in the free state before installation are as shown in FIGS. 4 and 5. As shown in the figure, their legs are spread apart toward each other. Second piece 13b of leg piece 13
Each of the legs is provided with an overhanging cylindrical portion 15 formed to protrude toward the other leg portion, that is, inwardly, by flange press molding from the second leg portion, and the overhang cylindrical portion An engagement hole 16 is formed, and the engagement hole is connected to the cylindrical engagement portion 9a of the boss portion 4.
It is designed to be circumscribed and engaged with.

A pair of contact pieces 14 are grooves 2a of the piston body 1.
In the free state before installation, as shown in FIG. 4, the distance Le between the tips is equal to the distance Lf between the bottoms of the pair of grooves 2a (see FIG. 2). It's a little bigger than that.

As shown in FIG. 5, the oil reservoir component 10 has a shelf plate portion 12 located on the side closer to the piston body 1, a pair of leg portions 13 corresponding to the boss portion 4, and a pair of abutting portions. The piston body 1 is moved with the piece 14 in the direction and posture corresponding to the groove 2a and with the pair of leg parts 13 being elastically deformed in the direction toward each other as shown by the imaginary lines in FIG. By being inserted toward the inner space, it can be attached to the piston body 1 with one touch by a spring action.

When the pair of leg portions 13 are elastically deformed in the direction toward each other as described above, the leg portions 13 are elastically bent along each of the first folding line A and the second folding line B. By doing so, a pair of leg pieces 1
The maximum outer distance between the two legs is equal to or smaller than the distance Lb between the tip surfaces 4a of the boss portions 4, and as a result, the cylindrical portion 15 protrudes toward the inside of the leg portions 13. The piece part 13 is inserted between the boss parts 4 without any force. When the oil reservoir component 10 is inserted into the inner space of the piston body 1 from the open end thereof, at the same time, the pair of contact pieces 14 are elastically deformed and engage with the groove 2a to slide therein. As a result, the oil reservoir component 10 is inserted into the piston 1 reliably and easily without wobbling as it is guided by the engagement between the pair of contact pieces 14 and the groove 2a.

When the pair of leg portions 13 are inserted between the boss portions 4 and the holes 16 are aligned with the cylindrical engagement portion 9a of the boss portion 4, the pair of leg portions 13 are elastically moved away from each other due to their own spring force. The outer surface of the second piece 13b around the hole 16 is pressed against the annular end surface 9b of the boss portion 4, and at the same time, the inner peripheral surface of the overhanging cylindrical portion 15 collapses over its entire surface and engages in a cylindrical shape. It is joined to the outer peripheral surface of the portion 9a. As a result, the piston pin hole 5
The oil reservoir component 10 is fixedly connected to the piston body 1 even if the piston pin is not passed through.

From the above explanation, in the piston according to the present invention, the oil sump structure can be improved without making major changes to the piston body for attaching the oil sump component, only by providing a stepped part on the outer periphery of the tip of the boss part. The member can be easily attached to the piston body with one touch, without requiring any special attachment parts or attachment tools, and without relying on the attachment of a piston pin. In particular, as in the illustrated embodiment, when the oil reservoir constituent member engages in a cylindrical manner with the outer periphery of the tip end of the boss portion at the overhanging cylindrical portion, the contact engagement area is relatively large, and this causes the oil The reservoir constituent member can be securely and reliably attached to the piston body. Since the overhanging cylindrical portion is easily formed by the collar overhanging process of sheet metal processing, this does not deteriorate the manufacturability of the oil reservoir component.
Further, since the projecting cylindrical portion is formed to protrude inside the leg portion, the projecting cylindrical portion does not get in the way when the oil reservoir component is inserted between the pair of boss portions.

The rotation around the piston pin hole 5 of the oil reservoir component 10 is prevented from rotating by the shelf plate part 1 as shown in FIG.
This is achieved by the two ends being adapted to just engage corresponding shoulders in the inner wall of the inner space of the piston body, such engagement being achieved by inserting the oil sump component into the piston body. This is easily and reliably achieved by each of the pair of contact pieces 14 sliding along the bottom of the groove 2a while being pressed by its own spring force.

When the oil reservoir component 10 is fixed in the inner space of the piston body 1 as described above, the shelf plate portion 12 is a plane (horizontal plane) perpendicular to the axis of the piston body 1.
An oil sump depression 1 is provided near the top wall 3.
1 constitutes an oil reservoir.

As clearly shown in FIGS. 3 and 4, the shelf portion 12 of the oil reservoir component 10 has wing portions 17 extending from the side edges in the vicinity of both ends, and the wing portions hold the oil. It acts to receive the water, and is provided only on one side near one end, and only on the other side near the other end.
As a result, a relatively large opening 18 is formed on the other side of the oil reservoir component 10 near the one end, and a relatively large opening 18 is formed between the piston body 1 and the other side near the other end. A relatively large opening 19 is provided between the piston body 1 and the piston body 1, one of which is used as an oil supply passage and the other as an oil discharge passage.

[Effects of the invention] As described above, according to the invention, the shelf plate portion of the oil sump component is inserted into the inner space of the cup-shaped piston body, faces the inner surface of the top wall of the piston body, and provides an oil sump. is directly attached to the piston body by a pair of leg pieces bent from both side edges, and the engaging part between the pair of leg pieces and the piston body is connected to the hub part provided on the piston body. Since the cylindrical parts formed by overhanging press-forming on the pair of leg pieces are designed to engage with the cylindrical engaging parts provided around the legs, the contact area between the two engaging parts is sufficiently large. In addition, the engagement between these cylindrical portions and the cylindrical engagement portion is a cylindrical engagement, and the engagement margin is large enough to maintain stable engagement. Since the distance is maintained by the elasticity of the pair of legs, the engaged state is maintained stably for a long period of time, and the engagement and disengagement are also easy. This can be easily achieved by elastically deforming the pair of leg pieces.
Attachment and detachment of the oil reservoir component to and from the piston body can be performed by extremely simple operations.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing one embodiment of a piston for an internal combustion engine according to the present invention, FIG. 2 is a sectional view taken along the line - of FIG. 1, and FIG. 3 is a sectional view taken along the line - of FIG.
4 is a perspective view of an oil reservoir component incorporated in the piston for an internal combustion engine according to the present invention shown in FIGS. 1 to 3, and FIG. 5 is a cross-sectional view of the piston for an internal combustion engine according to the present invention. FIG. DESCRIPTION OF SYMBOLS 1... Piston body, 2... Surrounding wall part, 2a... Groove, 3
...Top wall part, 4...Boss part, 4a...Top surface, 5...Piston pin hole, 6...Piston ring groove, 7...Oil ring groove, 8...Slit hole, 9...Stepped part, 9a...
Cylindrical engaging portion, 9b...Annular end surface, 10...Oil pool forming member, 11...Oil pool depression, 12...Shelf plate portion, 13
... Leg piece part, 13a... First piece part, 13b... Second piece part, 14... Leg piece part, 15... Overhanging cylindrical part, 16
...Engagement hole, 17... Wing part, 18, 19... Opening.

Claims (1)

[Scope of utility model registration request] A piston body having a top wall portion, a peripheral wall portion, and a pair of boss portions protruding inwardly facing each other, the boss portions having a piston pin hole, and a piston body inserted into the inner space of the piston body. an oil sump constituting member comprising a shelf plate section providing an oil sump recess facing the inner surface of the top wall section and a pair of leg pieces bent from both side edges of the shelf section; The oil reservoir component has a diameter reduced in steps around the inner end of the boss portion at an engagement hole formed by a press-formed cylindrical portion in which the pair of leg portions extend in directions facing each other. The cylindrical portion of the leg portion engages with the cylindrical engaging portion of the boss portion due to the elastic force that causes the pair of leg portions to open in the direction in which they separate from each other. A piston for an internal combustion engine, characterized in that the piston is attached to the piston body by being maintained in a state of engagement with the piston body.