JP2010059842A - Piston structure and oil jet system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piston structure and an oil jet system capable of preventing oil from reversely flowing out without disturbing flow-in of oil. <P>SOLUTION: This structure includes: an inlet channel 11 into which oil jetted from an oil jet flows and which extends in an oil flow direction; and the channel 12 of the back of crown surface including a slope part 121 formed on the back of a piston crown surface continuously to the inlet channel 11 and of which channel width expands as it gets closer to the inlet channel 11 in a longitudinal cross section view and a reverse flow prevention wall part 122 continuing the slope part 121 and changing a flow direction of oil reversely flowing along the slope part 121. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a piston structure and an oil jet system.

2. Description of the Related Art A piston having a cooling channel through which oil jetted from an oil jet flows is known. For example, in Patent Document 1, a guide wall is provided above the inlet passage so that oil flows smoothly into the cooling channel. Further, a step portion for preventing the oil from flowing backward is provided at the periphery of the inlet opening.
JP 2005-90448 A

  However, in the conventional piston structure described above, the flow passage cross-sectional area of the cooling channel is reduced by a guide wall or step provided near the oil inlet passage. For this reason, the inflow of oil was hindered, and the amount of oil supplied was reduced.

  The present invention has been made paying attention to such conventional problems, and a piston structure and an oil jet system that are capable of preventing the oil from flowing back and flowing without being inhibited. The purpose is to provide.

  The present invention solves the above problems by the following means. In addition, in order to make an understanding easy, although the code | symbol corresponding to embodiment of this invention is attached | subjected, it is not limited to this.

  The present invention includes an inlet channel (11) extending in the oil flow direction, in which oil injected from an oil jet flows, and a back surface of a piston crown formed continuously to the inlet channel (11). A slope portion (121) that expands the width of the flow passage as it approaches the inlet flow passage (11) when viewed in a plane, and the oil that flows back along the slope portion (121) continuously to the slope portion (121). It has a backflow prevention wall part (122) which changes a flow direction, and a coronal back surface flow path (12) containing it, It is characterized by the above-mentioned.

  According to the present invention, the crown-side back channel is formed with the slope portion that expands the channel width as it approaches the inlet channel, and the backflow prevention wall portion that continues to the slope portion. Therefore, the oil that has flowed back along the slope portion collides with the backflow prevention wall portion and changes the flow direction, so that it is difficult for oil to flow out of the inlet channel even if there is backflow oil.

Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings.
(First embodiment)
FIG. 1 is a view showing a first embodiment of a piston structure according to the present invention. FIG. 1 (A) is a cross-sectional view taken along the line A-A in FIG. 1 (C), and FIG. -B sectional drawing, FIG.1 (C) is a front view, FIG.1 (D) is a longitudinal cross-sectional view of FIG.1 (C).

  The piston 10 includes an inlet channel 11, a crown surface back channel 12, and an outlet channel 13.

  The oil injected from the oil jet flows into the inlet channel 11. The inlet channel 11 extends in the oil flow direction. In this embodiment, the piston 10 is formed so as to pass through from the bottom to the top.

  The coronal back channel 12 is formed continuously with the inlet channel 11. The crown surface back channel 12 is formed behind the piston crown surface 10a. The coronal back channel 12 is formed along the outer periphery of the piston 10. As shown in FIG. 1B, the coronal back surface flow path 12 includes a slope portion 121 and a backflow prevention wall portion 122.

  The slope portion 121 is an inclined surface that increases the width of the channel as it approaches the inlet channel 11 when viewed in a vertical cross section (FIG. 1B).

  The backflow prevention wall portion 122 is continuous with the slope portion 121. The backflow prevention wall 122 is an inclined wall surface connecting the slope end 121a and the inlet flow path end 11a. The backflow prevention wall 122 rises so as to reduce the channel width as it approaches the inlet channel end 11a.

  The outlet channel 13 is formed continuously with the crown surface back channel 12. The oil that flows through the coronal back channel 12 flows out from the outlet channel 13.

  FIG. 2 is a diagram for explaining the operation of the piston structure of the first embodiment. FIG. 2 (A) shows the main flow of oil injected from the oil jet, and FIG. 2 (B) shows the oil flow in the comparative embodiment. FIG. 2C shows the flow of oil in this embodiment.

  As shown by the arrow in FIG. 2A, the oil jetted from the oil jet 20 flows into the crown surface back channel 12 via the inlet channel 11 and flows out from the outlet channel 13.

  At this time, when the coronal back channel 12 has a smooth shape as shown in FIG. 2B, oil flows from the inlet channel 11 into the coronal back channel 12 as indicated by thin arrows. For example, when the piston is lifted, it flows backward from the inlet flow path 11 as shown by a thick arrow due to the influence of inertial force. For this reason, the amount of oil flowing through the crown surface back channel 12 is reduced.

  On the other hand, in this embodiment, the coronal back surface flow path 12 is formed so as to include a slope portion 121 and a backflow prevention wall portion 122. For this reason, when the oil flowing into the coronal back channel 12 as shown by a thin arrow flows backward, it flows along the slope portion 121 as shown by a thick arrow. The backflow prevention wall 122 is an inclined wall surface connecting the slope end 121a and the inlet channel end 11a, and rises so as to reduce the channel width as it approaches the inlet channel end 11a. For this reason, the oil that has flowed back along the slope portion 121 collides with the backflow prevention wall portion 122 and changes its flow direction. Therefore, even if there is backflow oil, it is difficult for the oil to flow out of the inlet channel 11.

  FIG. 3 is a view showing the inflow / outflow amount of oil flowing through the inlet channel. The crank angles 360 deg and 720 deg on the horizontal axis are the top dead center (TDC), and the crank angle 540 deg is the bottom dead center (BDC). The vertical axis shows the inflow and outflow of oil, with the amount of inflow increasing from the top to zero and the amount of outflow decreasing from the bottom. The oil jet ejects a certain amount of oil regardless of the crank angle.

  When the piston descends from TDC to BDC, the direction of movement of the piston and the direction of oil ejection are opposite, so that oil tends to enter from the inlet channel.

  Also, when the piston rises from BDC to TDC, the direction of movement of the piston and the direction of oil ejection coincide with each other, so that it is difficult for oil to enter from the inlet flow path, and the oil flows backward due to the influence of inertia and the inlet flow path 11 It becomes easy to flow out from. It can be seen from FIG. 3 that a large amount of oil has flowed out particularly near the crank angle of 600 deg.

  On the other hand, according to the crown surface back flow path 12 of the present embodiment including the slope portion 121 and the backflow prevention wall portion 122, the backflow oil flowing out from the inlet flow path 11 can be reduced by the hatched area in FIG. is there. Therefore, good piston cooling performance can be obtained, and as a result, knock resistance can be improved.

  Moreover, according to this embodiment, the slope part 121 and the backflow prevention wall part 122 were formed in the lower side (inlet flow path side) of the crown surface back flow path 12. In this way, a sufficient thickness can be ensured without reducing the thickness from the crown surface back flow path 12 to the piston crown surface 10a. In the crown wall thickness, a lower limit wall thickness that should be secured at least in order to secure performance such as strength is defined. If the lower limit thickness cannot be ensured, measures such as lowering the coronal back channel 12 as a whole are required to ensure the lower limit thickness. If the crown back channel 12 is lowered as a whole, the distance from the crown surface is increased and the cooling effect is reduced. However, according to the structure of the present embodiment, such a countermeasure is unnecessary, and good piston cooling performance can be obtained.

(Second Embodiment)
FIG. 4 is a view showing a second embodiment of the piston structure according to the present invention, FIG. 4 (A) is an enlarged sectional view showing the structure of the second embodiment, and FIG. It is a figure explaining the effect | action of 2 embodiment.

  As shown in FIG. 4A, the backflow prevention wall portion 122 of the present embodiment is connected to the inlet flow channel end 11a via a curved portion 123 that protrudes upward from the coronal back channel 12. The backflow prevention wall portion 122 rises so as to reduce the flow path width as it approaches the curved portion 123.

  Even in such a structure, the backflow oil flows along the slope portion 121 as shown by a thick arrow as shown in FIG. 4B, and the flow direction is changed by the backflow prevention wall portion 122. Therefore, the backflow oil is difficult to flow out from the inlet flow path 11.

  Further, in the present embodiment, the curved portion 123 that is continuous with the inlet channel end 11a is formed, so that the oil that flows from the inlet channel 11 as indicated by a thin arrow does not peel along the curved portion 123 and is crowned. It flows smoothly into the back surface flow path 12.

(Third embodiment)
FIG. 5 is a view showing a third embodiment of the piston structure according to the present invention, FIG. 5 (A) is an enlarged sectional view showing the structure of the third embodiment, and FIG. It is a figure explaining the effect | action of 3 embodiment.

  As shown in FIG. 5 (A), the backflow prevention wall portion 122 of the present embodiment is connected to the inlet flow channel end 11a via a curved portion 123 that protrudes upward from the coronal back channel 12. The curved portion end 123a protrudes more to the crown surface back flow passage oil flow direction side than the slope end 121a when viewed in a longitudinal section.

  Since it comprised in this way, backflow oil flows along the slope part 121 like a thick arrow as shown in FIG.5 (B), and a flow direction is changed by the backflow prevention wall part 122. FIG. And since especially the curved part edge 123a protrudes in the crown surface back flow path oil flow direction side rather than the slope end 121a, the backflow prevention wall part 122 has a reverse slant shape, so that the backflow oil flows from the inlet flow path 11. It becomes even more difficult to flow out.

  Without being limited to the embodiments described above, various modifications and changes are possible within the scope of the technical idea, and it is obvious that these are also included in the technical scope of the present invention.

  In the above description, the case where the slope portion 121 and the backflow prevention wall portion 122 are formed on the lower side (inlet channel side) of the crown surface back channel 12 is described as an example. However, as shown in FIG. The slope part 121 and the backflow prevention wall part 122 may be formed on the upper side of the flow path 12 (opposite the inlet flow path).

  Even in this way, the backflowed oil flows along the slope portion 121 and collides with the backflow prevention wall portion 122 to change the flow direction. Therefore, even if there is backflow oil, it is difficult for the oil to flow out from the inlet channel 11.

It is a figure which shows 1st Embodiment of the piston structure by this invention. It is a figure explaining the effect | action of the piston structure of 1st Embodiment. It is the figure which showed the inflow / outflow amount of the oil which flows through an entrance flow path. It is a figure which shows 2nd Embodiment of the piston structure by this invention. It is a figure which shows 3rd Embodiment of the piston structure by this invention. It is a figure which shows other embodiment of the piston structure by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Piston 10a Piston crown surface 11 Inlet flow path 11a Inlet flow path end 12 Crown surface back flow path 121 Slope part 121a Slope end 122 Backflow prevention wall part 123 Curved part 20 Oil jet

Claims (5)

Oil injected from the oil jet flows in, and an inlet flow path extending in the oil flow direction;
A slope part that is formed on the back surface of the piston crown continuously to the inlet channel, and that expands the channel width as it approaches the inlet channel when viewed in a longitudinal section, and along the slope part continuously to the slope part A reverse flow prevention wall portion that changes the flow direction of the oil that has flowed backward,
Piston structure having The backflow prevention wall portion connects the slope end and the inlet flow path end, and rises so as to reduce the flow path width as it approaches the inlet flow path end.
The piston structure according to claim 1. The backflow prevention wall portion is connected to the inlet channel end through a curved portion when viewed in a longitudinal section, and rises to reduce the channel width as the curved portion is approached,
The piston structure according to claim 1. The backflow prevention wall is connected to the inlet channel end via a curved portion when viewed in a longitudinal section,
The end of the curved portion protrudes to the coronal back channel oil flow direction side from the slope end when viewed in a longitudinal section,
The piston structure according to claim 1. An oil jet that injects engine oil onto the lower surface of the piston;
A piston including an annular cooling channel formed in the circumferential direction of the piston and circulating engine oil supplied from the oil jet;
In an oil jet system with
The annular cooling channel is formed with an inlet channel that opens in the direction of the lower surface of the piston in order to supply engine oil supplied from the oil jet into the piston.
In the annular cooling channel, the flow passage cross section is expanded in the vicinity of the inlet flow passage in comparison with the flow passage cross section far from the inlet flow passage in order to change the flow direction of the backflowing oil.
An oil jet system characterized by that.

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