JP4177173B2 - Piston for internal combustion engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The invention of this application relates to a piston for an internal combustion engine used in a vehicle or the like.
[0002]
[Prior art]
When the operation of the internal combustion engine is stopped, the internal combustion engine piston drops into the oil pan from the sliding gap between the outer peripheral surface and the cylinder hole, and sufficient lubrication with the lubricating liquid is performed at the next engine start. It may not be possible.
[0003]
The following has been devised as a piston for an internal combustion engine to cope with this (see Patent Document 1).
[0004]
This piston is used for an internal combustion engine in which the axis of the piston is oriented in the vertical direction, but an oil reservoir groove is provided at a position below the oil ring groove in the outer peripheral surface of the piston body, and during operation of the internal combustion engine, The lubricating liquid can be stored in the oil reservoir groove portion. When the engine is restarted after the internal combustion engine is stopped, the lubricating liquid is supplied to the gap between the piston body and the cylinder hole from the oil reservoir groove.
[0005]
[Patent Document 1]
Japanese Utility Model Publication No. 61-37448 [0006]
[Problems to be solved by the invention]
However, in this conventional piston for an internal combustion engine, the vertical lower end portion of the oil sump groove formed on the outer peripheral surface of the piston main body is in contact with the sliding gap along the vertical direction of the piston main body and the cylinder hole. When the operation of the internal combustion engine is stopped for a long period of time, the lubricating liquid stored in the oil reservoir groove gradually drops to the oil pan side through the sliding gap.
[0007]
Therefore, the invention of this application reduces the sliding resistance when starting the engine by ensuring that the lubricating liquid can be kept between the piston body and the cylinder hole even when the internal combustion engine is stopped for a long period of time. It is an object of the present invention to provide a piston for an internal combustion engine that can be used.
[0008]
[Means for Solving the Problems]
As a means for solving the above-described problems, the invention described in claim 1 includes a thick disc-shaped piston head portion located at the top portion and an oil ring groove for accommodating the oil ring , A piston used in an internal combustion engine whose axis is inclined with respect to a vertical direction,
An oil reservoir that can store lubricating liquid is continuously formed from the oil ring groove to the outer peripheral surface side of the skirt portion at the upper position in the vertical direction of the outer peripheral surface of the piston body that is in sliding contact with the cylinder hole. And an oil discharge hole that connects the inside of the oil ring groove and the back side of the piston head portion in the circumferential direction of the oil ring groove. It is characterized by being spaced apart on both sides.
[0009]
In the case of this invention, since the oil reservoir is provided at the upper position in the vertical direction of the outer peripheral surface of the piston body, the lubrication stored in the oil reservoir even when the internal combustion engine is stopped for a long period of time. The liquid does not flow down to the oil pan through the gap with the cylinder hole. Therefore, when the internal combustion engine is started, the sliding portion between the piston body and the cylinder hole can be reliably lubricated by the lubricating liquid in the oil reservoir. Further, the lubricating liquid is easily retained at the lower position in the vertical direction of the outer peripheral surface of the piston body by the surface tension of the lubricating liquid in the oil reservoir at the upper position. At this time, even if the lubricating liquid at the lower position in the vertical direction flows down, the lubricating liquid in the oil reservoir flows at the start of the engine, so that the lower side in the vertical direction can be sufficiently lubricated.
[0013]
Further, since the oil reservoir is formed continuously in the oil ring groove, the lubricating liquid scraped off by the oil ring during operation of the internal combustion engine can be supplied to the oil reservoir more reliably, Since the oil ring is almost in close contact with the inner surfaces of both sides of the oil ring groove in the axial direction, there is no problem that the lubricating liquid stored in the oil reservoir flows down through the oil ring groove when the engine is stopped.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Next, an embodiment of the invention of this application will be described with reference to FIGS.
[0015]
As shown in FIG. 2, the internal combustion engine of this embodiment has a V-shaped configuration in which a plurality of cylinder holes 1 (cylinders) are arranged in a V shape around a crankshaft (not shown). An internal combustion engine, each cylinder hole 1 and a piston 2 accommodated in the cylinder hole 1 are inclined at a predetermined angle with respect to the vertical direction. In FIG. 2, 3 indicates a connecting rod, and 4 indicates an oil pan.
[0016]
As shown in FIGS. 1, 3, and 4, the piston 2 includes a thick disc-shaped piston head portion 5 positioned at the top of the piston body, and extends from the piston head portion 5 along the axial direction. A protruding skirt portion 6 and a pin boss portion 7 that rotatably supports a piston pin (not shown) on the back side of the piston head portion 5 are provided.
[0017]
On the outer peripheral surface of the piston head portion 5, two ring grooves 9 and 10 for accommodating and arranging the compression ring 8 and one oil ring groove 12 for accommodating the oil ring 11 are arranged along the axial direction. An oil discharge hole 13 is formed at the bottom of the oil ring groove 12 to connect the inside of the groove 12 and the back side of the piston head part 5. As shown in an enlarged view in FIG. 1, the oil ring 11 is formed by connecting a pair of side rails 14 and 14 by a resilient ring 15 having a resilient force in the width direction. Due to the action, both side rails 14, 14 are brought into pressure contact with opposing side surfaces 16, 16 (both inner surfaces in the axial direction) of the oil ring groove 12.
[0018]
The skirt portion 6 is formed by an arc surface continuous to the outer peripheral surface of the piston head portion 5, but the two regions where the pin boss portions 7 are present are cut out over a predetermined angle range. The two regions a and b of the skirt portion 6 that extend in the axial direction without being cut out are respectively an upper region and a lower region when the piston 2 is accommodated in the cylinder hole 1 in an inclined posture. Become.
[0019]
And the recessed part 17 as an oil reservoir part is formed in the position corresponding to the said upper area | region a in the outer peripheral surface of the skirt part 6, ie, a vertical direction upper side position. The concave portion 17 is formed continuously from the edge of the oil ring groove 12 to the skirt portion 6 side.
[0020]
As described above, the internal combustion engine piston 2 has a concave portion 17 formed continuously from the lower edge of the piston ring groove 12 at the upper position in the vertical direction of the outer peripheral surface of the skirt portion 6. During operation of the internal combustion engine, a sufficient amount of lubricating liquid flows into the recess 17. Since the piston 2 is attached to the V-type internal combustion engine so that the concave portion 17 is positioned vertically upward, when the internal combustion engine stops from this state, the lubricating liquid flowing into the concave portion 17 flows downward. It is stored as it is.
[0021]
The recess 17 communicates with the oil ring groove 12 extending over the outer periphery of the piston head portion 5, and the side rail 14 of the oil ring 11 is pressed against the side surface 16 of the oil ring groove 12 by a resilient ring 15. Therefore, the leakage of the lubricating liquid through the oil ring groove 12 is reliably prevented by the pressure contact action of the side rail 14.
[0022]
Further, as described above, a sufficient amount of lubricating liquid is stored in the vertical upper position of the outer peripheral surface of the skirt portion 6 by the concave portion 17 as described above. The retention of the lubricating liquid is maintained by the surface tension.
[0023]
Therefore, even when the internal combustion engine is stopped for a long period of time, when the internal combustion engine is restarted, the piston operation with less friction can be obtained by the recess 17 and the lubricating liquid staying therearound. At the lower position in the vertical direction on the outer periphery of the skirt portion 6, there is a possibility that it will flow downward depending on the stop period of the internal combustion engine. However, if the piston 1 starts a stroke when the engine is restarted, The lubricating liquid flows down to the lower side in the vertical direction on the outer periphery of the skirt portion 6, so that this portion can be quickly lubricated.
[0024]
The embodiment of the present invention is not limited to that described above. For example, in the above embodiment, the piston according to the present invention is applied to a V-type internal combustion engine, but as shown in FIG. The present invention can also be applied to a horizontally opposed internal combustion engine in which pistons 1 are disposed on both sides in the horizontal direction with a crankshaft interposed therebetween.
[0025]
Next, inventions other than those described in the claims that can be grasped from the above-described embodiment will be described together with the effects thereof.
[0026]
(A) The internal combustion engine is a V-type internal combustion engine, and the piston for an internal combustion engine according to any one of claims 1 to 3.
[0027]
(B) The piston for an internal combustion engine according to any one of claims 1 to 3, wherein the internal combustion engine is a horizontally opposed internal combustion engine.
[0028]
In any of these internal combustion engines, the piston operating stroke is short, and the supply of lubricating fluid from the crankshaft side to the piston tends to be insufficient when the engine is started. The problem of insufficient lubrication can be solved reliably.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a piston showing a first embodiment of the invention of this application.
FIG. 2 is a partial cross-sectional front view of the internal combustion engine showing the embodiment.
FIG. 3 is a side view of a piston showing the embodiment.
4 is a cross-sectional view taken along line AA of FIG. 3 showing the embodiment.
FIG. 5 is a partial cross-sectional front view of an internal combustion engine showing another embodiment of the invention of this application.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Cylinder hole 2 ... Piston 6 ... Skirt part 11 ... Oil ring 12 ... Oil ring groove | channel 16 ... Side surface (Axial direction both sides inner surface)
17 ... concave portion (oil reservoir)

Claims (1)

A piston for use in an internal combustion engine having a thick disc-shaped piston head portion located at the top and an oil ring groove for accommodating an oil ring, the axis of the piston being inclined with respect to the vertical direction. ,
An oil reservoir capable of storing lubricating liquid is formed continuously from the oil ring groove to the outer peripheral surface side of the skirt portion at the upper position in the vertical direction of the outer peripheral surface of the piston body that is in sliding contact with the cylinder hole ,
The oil ring is in pressure contact with both axial inner surfaces of the oil ring groove;
An internal combustion engine characterized in that an oil discharge hole for connecting the inside of the oil ring groove and the back side of the piston head portion is provided on both sides of the oil reservoir in the circumferential direction of the oil ring groove. Piston.

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