JP3346068B2 - Internal combustion engine piston - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piston for an internal combustion engine.

[0002]

2. Description of the Related Art A piston for an internal combustion engine having a compression ring and an oil ring arranged on a peripheral surface of a piston in order from the top surface side of the piston is known (see Japanese Utility Model Application Laid-Open No. 60-89462). Normally, the compression ring and the oil ring are received in a compression ring receiving groove and an oil ring receiving groove formed on the peripheral surface of the piston, respectively. The compression ring is usually made of metal, and the compression ring contacts the top surface of the compression ring receiving groove and the inner wall surface of the cylinder bore to radiate heat from the piston to the inner wall surface of the cylinder bore via the compression ring. The piston is cooled as much as possible.

[0003]

On the other hand, the compression ring and the oil ring also have a sealing function to prevent the combustion gas in the combustion chamber, that is, the so-called blow-by gas from leaking into the crank chamber. However, a small blow-by gas leakage path is formed between the compression groove and the oil ring and the corresponding receiving groove and the inner wall surface of the cylinder bore, and the blow-by gas leaks into the crank chamber through the blow-by gas leakage path. In particular, a normal metal compression ring is provided with an abutment for receiving the compression ring in the compression ring receiving groove, so that the flow area of the blow-by gas leakage path formed around the compression ring is reduced. Is relatively large. In this case, if the blow-by gas leaked through the blow-by gas leakage path around the compression ring leaks relatively easily through the blow-by gas leakage path formed around the oil ring, the top surface of the compression ring is located inside the combustion chamber. Although a high pressure close to the pressure acts, a relatively low pressure acts on the bottom surface of the compression ring. However,
When the pressure acting on the top surface of the compression ring becomes significantly greater than the pressure acting on the bottom surface, the compression ring is maintained in a state of not contacting the top surface of the compression ring receiving groove. However, if the compression ring is kept out of contact with the top surface of the compression ring receiving groove where the temperature is high, it is impossible to satisfactorily dissipate heat from the piston to the inner wall surface of the cylinder bore through the compression ring. There's a problem. The above publication does not suggest this problem at all.

[0004]

According to a first aspect of the present invention, at least one compression ring made of metal is arranged on a peripheral surface of a piston in order from a top surface side of the piston. In the piston of the internal combustion engine equipped with an oil ring, the flow path resistance of the blow-by gas leakage path formed around the compression ring,
Make the oil ring smaller than the flow path resistance of the blow-by gas leakage path formed around the oil ring,
Formed from a resin annular body that extends continuously without having

In order to solve the above problem, a second
According to the invention, the top surface side of the piston is
At least one metal complex arranged in order from
Of an internal combustion engine equipped with a shock ring and an oil ring.
Formed around the compression ring in the piston
The flow resistance of the blow-by gas leakage path
Flow resistance of the blow-by gas leakage path formed around the
Of the piston that receives the oil ring
Install the oil ring in the cylinder bore in the oil ring receiving groove
An urging member for urging toward the wall surface is provided, and the urging member is
Compression ring made of thermally expandable material
Fits at least one compression ring
Compression forming the mouth and defining the abutment
Both ends of the ring overlap each other after assembly
It is sea urchin.

Further , according to the third invention, the first or
In the second invention, the oil ring is formed from a fiber composite resin. According to the fourth invention,
In the eye or the second invention, an abutment is formed in the oil ring, and both ends of the oil ring defining the abutment overlap each other after the assembly.

Further , according to the fifth aspect, the first or second aspect is provided.
In the second invention, a lubricating oil release passage for releasing the lubricating oil scraped off by the oil ring from the peripheral surface of the piston is provided, and the lubricating oil release passage is opened in an oil ring receiving groove of the piston for receiving the oil ring. The opening is formed in the piston peripheral surface between the oil ring receiving groove and the bottom end of the piston without causing the oil ring to be opened.

[0008]

According to the first or second aspect of the present invention, the flow path resistance of the blow-by gas leakage path around the compression ring is made smaller than the flow path resistance of the blow-by gas leakage path around the oil ring. The blow-by gas leaked through the blow-by gas leak path is sealed by an oil ring. In this case, the pressure difference between the top side and the bottom side of the compression ring is reduced, so that the compression ring moves up and down with respect to the piston in the compression ring receiving groove, that is, so-called fluttering is likely to occur. When the compression ring causes fluttering, the frequency of contact of the top surface of the compression ring with the top surface of the compression ring receiving groove increases, so that good heat radiation from the piston to the inner wall surface of the cylinder bore is ensured.

Furthermore the invention set forth in claim 1, the oil ring, flow resistance of the blow-by gas leakage path is very large around the oil ring so to form an annular body extending continuously without having split end Is done. Claim 2
In the invention described in the above, further provided in the oil ring receiving groove
The oil ring is moved by the biasing member
Because it is urged toward the surface, the oil ring and
Blow-by gas leakage formed between cylinder bore inner wall surfaces
The flow path resistance of the road is extremely increased. Moreover, the urging member
Is formed from a heat-expandable material, so it is energized during cold operation.
The oil ring and cylinder bore
The frictional resistance between the inner wall surfaces is reduced. In this case,
Sealing effect is reduced, but compression
The two ends of the ring
The amount of blow-by gas reaching the cooling chamber is reduced. According to the third aspect of the present invention, since the oil ring is formed of a fiber composite resin having a small coefficient of linear thermal expansion, even when a joint is formed in the oil ring, a blow-by gas leakage path around the oil ring is formed. The flow path resistance is extremely increased.

According to the fourth aspect of the present invention, since both ends of the oil ring overlap each other, the flow path resistance of the blow-by gas leakage path around the oil ring is extremely increased .

[0011]

According to the fifth aspect of the present invention, since the lubricating oil release passage is opened in the peripheral surface of the piston between the oil ring receiving groove and the bottom end of the piston, the oil ring always contacts the bottom surface of the oil ring receiving groove. Even if it does, the excess lubricating oil is satisfactorily removed.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG.
, A combustion chamber formed between the top surface 1a of the piston 1 and a cylinder head (not shown), and 5 represents a crank chamber. On the peripheral surface 1a of the piston 1, the piston 1
A first compression ring receiving groove 6, a second compression ring receiving groove 7, and an oil ring receiving groove 8, which are arranged in order from the top surface 1b. Each of the first compression ring receiving groove 6, the second compression ring receiving groove 7, and the oil ring receiving groove 8 has an annular shape, and has a rectangular cross section.

In the first compression ring receiving groove 6, a first compression ring 9 formed of metal, for example, stainless steel, is received. The first compression ring 9 is provided with an abutment 10 as shown in FIG.
In this case, a pair of end faces 11, 12 facing each other without overlapping each other are provided at both ends of the first compression ring 9 defining the abutment 10. The first compression ring 9 is provided with
It becomes easy to insert the compression ring 9 into the first compression ring receiving groove 6. In the following, the abutment as shown in FIG. 2 is referred to as a normal abutment.

A second compression ring 13 similar to the first compression ring 9 is received in the second compression ring receiving groove 7. That is, the second compression ring 13 is formed from metal and usually has an abutment.

On the other hand, in the oil ring receiving groove 8, resin,
For example, an oil ring 14 formed of a fluororesin such as polytetrafluoroethylene is received. This oil ring 14 is formed of an annular body that extends continuously without having an abutment. When the oil ring 14 is formed of resin, the oil ring 14 can be relatively easily inserted into the oil ring receiving groove 8 without providing an abutment.

After the piston 1 is inserted into the cylinder bore 3, the first and second compression rings 9, 13 and the oil ring 14 are held in a press-fit state. Therefore, the first and second compression rings 9, 13 and the oil ring 14 are urged toward the cylinder bore inner wall surface 3a by their own tension.

Still referring to FIG. 1, the skirt portion 1d of the piston 1 formed between the oil ring receiving groove 8 and the bottom end portion 1c of the piston 1 penetrates the skirt portion 1d and has a peripheral surface 1a of the piston 1. A lubricating oil release passage 15 extending from the crankcase 5 to the crank chamber 5 is formed.

During operation of the engine, the first and second compression rings 9 and 13 and the oil ring 14 prevent the combustion gas in the combustion chamber 4 from leaking into the crank chamber 5 as much as possible. The sealing function prevents the lubricating oil from flowing into the combustion chamber 4 due to the pressure. In particular, the first and second compression rings 9, 13 dissipate heat from the piston 1 to the inner wall surface 3a of the cylinder bore via them, thereby acting to cool the piston 1. Furthermore, especially the oil ring 14
Cylinder bore inner wall surface 3 by lubricating oil supply device not shown
It works to reduce consumption of lubricating oil by scraping off excess lubricating oil out of the lubricating oil supplied on a.

As described above, the first and second compression rings 9 and 13 have a sealing function to seal the combustion gas in the combustion chamber 4, that is, the blow-by gas from leaking. However, a minute gap is formed between the first compression ring 9 and the inner wall surface 3a of the cylinder bore or between the first compression ring 9 and the first compression ring receiving groove 6, and blow-by gas leaks through these gaps. . Therefore, these gaps formed around the first compression ring 9 constitute a blow-by gas leakage path. Similar blow-by gas leakage paths are also formed around the second compression ring 13 and around the oil ring 14. In particular, when the first and second compression rings 9 and 13 are each provided with a normal opening as in the embodiment shown in FIG. 1, these first and second compression rings 9 and 1 are used.
The flow passage area of the blow-by gas leakage path around the three becomes relatively large.

However, the flow path resistance of the blow-by gas leakage path around the oil ring 14 is larger than the flow path resistance of the blow-by gas leakage path around the first compression ring 9 and the second path.
If it is smaller than the sum of the flow path resistance of the blow-by gas leakage path around the compression ring 13, for example, the second
The blow-by gas leaked through the blow-by gas leak path around the compression ring 13 leaks into the crank chamber 5 in a relatively short time, and therefore, a relatively low pressure acts on the bottom surface of the second compression ring 13. become. On the other hand, a relatively high pressure close to the pressure in the combustion chamber 4 acts on the top surface of the second compression ring 13, so that the second compression ring 13 is placed on the top surface of the second compression ring receiving groove 7. It will be kept in a non-contact state.

On the other hand, as described above, the first and second compression rings 9 and 13 function to cool the piston 1 by radiating heat from the piston 1 to the inner wall surface 3a of the cylinder bore. In this case, the first and second compression rings 9 and 13 dissipate heat by contacting the wall surfaces of the corresponding compression ring receiving grooves 6 and 7, respectively.
In this case, the first and second compression rings 9,
13 is a corresponding compression ring receiving groove 6, 7
The heat dissipating action is performed more favorably when the top wall close to the combustion chamber 4 is contacted. However, as described above, when the first and second compression rings 9 and 13 are kept out of contact with the top surfaces of the corresponding compression ring receiving grooves 6 and 7, the heat radiating action from the piston 1 to the cylinder bore inner wall surface 3a is reduced. It does not work well. Therefore, in the embodiment according to the present invention, the flow path resistance of the blow-by gas leakage path around the first and second compression rings 9 and 13 is made smaller than the flow path resistance of the blow-by gas leakage path around the oil ring 14. In other words, the first
Also, by providing a normal opening in the second compression rings 9 and 13 and forming the oil ring 14 from an annular body having no opening, the flow of the blow-by gas leakage path around the first and second compression rings 9 and 13 is improved. The passage area is larger than the passage area of the blow-by gas leakage passage around the oil ring 14. As a result, it is possible to prevent the blow-by gas from leaking from the blow-by gas leakage path around the oil ring 14 in a short time, for example, to prevent the pressure acting on the bottom surface of the second compression ring 13 from decreasing. The pressure difference between the pressure acting on the top surface of the second compression ring 13 and the pressure acting on the bottom surface of the second compression ring 13 can be reduced. When the pressure difference between the pressure acting on the top surface and the pressure acting on the bottom surface of the second compression ring 13 becomes small, the second compression ring 13 moves up and down with respect to the piston 1 in the second compression ring receiving groove 7, that is, so-called. Fluttering is likely to occur. When the second compression ring 13 generates fluttering, the frequency of contact between the top surface of the second compression ring 13 and the top surface of the second compression ring receiving groove 7 increases. Therefore, good heat radiation from the piston 1 to the cylinder bore inner wall surface 3a can be ensured. First
Since the same applies to the compression ring 9, the description is omitted.

However, when the first and second compression rings 9 and 13 cause fluttering, a relatively large space is formed between the first and second compression rings 9 and 13 and the corresponding wall surfaces of the compression ring receiving grooves 6 and 7. A blow-by gas leak path is formed. That is,
For example, the second compression ring 13 may be brought into contact with neither the top surface nor the bottom surface of the second compression ring receiving groove 7, and as a result, as shown by an arrow A in FIG. Through which a relatively large amount of blow-by gas can leak. However, in this embodiment, since the oil ring 14 is formed of an annular body having no abutment, even if the blow-by gas leaks through the first and second compression rings 9 and 13, The gas can be extremely reduced. Therefore, it is possible to reduce the deterioration of the blow-by gas due to contact with the lubricating oil.

On the other hand, if the flow area of the blow-by gas leakage path around the first and second compression rings 9 and 13 is made larger than the flow area of the blow-by gas leakage path around the oil ring 14, The pressure acting on the surface becomes higher than the pressure acting on the bottom surface of the oil ring 14, so that the oil ring 14 is kept in contact with the bottom surface of the oil ring receiving groove 8 as shown in FIG. Become. For this reason, the oil ring 14
Thus, a better sealing effect of the blow-by gas is secured.

Conventionally, a lubricating oil release passage is opened in the oil ring receiving groove 8. However, when the oil ring 14 is held in contact with the bottom surface of the oil ring receiving groove 8 as in this embodiment, and the lubricating oil escape passage is opened into the oil ring receiving groove 8, the oil ring 14 This prevents the lubricating oil from flowing into the lubricating oil escape passage. Further, blow-by gas leaked from the blow-by gas leak path around the second compression ring 13 reaches the crank chamber 5 via the lubricant oil release passage.
Therefore, in the embodiment shown in FIG. 1, the lubricating oil release passage 15 is opened in the piston peripheral surface 1a in the skirt portion 1d without opening in the oil ring receiving groove 8. As a result, excess lubricating oil scraped off by the oil ring 14 can be easily released from the piston peripheral surface 1a, and therefore, consumption of lubricating oil can be reduced. Moreover, it is possible to prevent the blow-by gas from reaching the crank chamber 5 through the lubricating oil release passage 15.

Further, in this embodiment, since the oil ring 14 is formed of a resin, the frictional resistance between the oil ring 14 and the inner wall surface 3a of the cylinder bore can be reduced, thereby contributing to an improvement in engine output. . Further, since the resin oil ring 14 is excellent in heat resistance, the durability of the oil ring 14 can be improved.

Next, another embodiment of the oil ring will be described with reference to FIGS. Referring to FIG. 4, in the present embodiment, a biasing member 16 is disposed between the oil ring receiving groove 8 and the oil ring 14. In the example shown in FIG.
6 is plate-shaped, and the biasing member 16 is an oil ring 14.
To the cylinder bore inner wall surface 3a, thereby acting to minimize the blow-by gas leakage path formed between the cylinder bore inner wall surface 3a and the oil ring 14. Therefore, the amount of blow-by gas that reaches the inside of the crank chamber 5 through the blow-by gas leakage path around the oil ring 14 can be further reduced. Note that the biasing member 16 may be formed of a wire or a spring.

The oil ring 14 of the present embodiment is provided with an abutment 17 as shown in FIG. In the oil ring 14 shown in FIG. 5, a concave portion is formed at one end of the oil ring 14 that defines the abutment 17, and a convex portion having a shape corresponding to the concave portion is formed at the other end of the oil ring 14. The concave and convex portions overlap each other. In the example shown in FIG. 5A, both ends of the oil ring 14 overlap each other in the axial direction of the piston 1, and in the example shown in FIG. 5B, they overlap each other in the radial direction of the piston 1. In the example shown in (C), the pistons 1 overlap each other in the axial direction and the radial direction. Such an abutment is hereinafter referred to as a polymerization abutment. By providing the overlapping opening 17 as shown in FIG. 5 on the oil ring 14, the flow resistance of the blow-by gas leakage path around the oil ring 14 can be extremely increased as compared with the case where the ordinary opening is provided.

Further, in the present embodiment, the oil ring 14 is formed of a fiber composite resin formed by mixing fibers into a fluorine resin, for example. Generally, the coefficient of linear expansion of such a fiber composite resin is small, so that an increase in the opening clearance during operation of the engine is prevented.
Even in the case where the abutment 17 is provided in the 4, the flow path area of the blow-by gas leakage path can be reduced. The oil ring 14 may be formed of a metal or resin annular body that extends continuously without having an abutment, and the urging member 16 may be applied. The other configuration and operation of the piston 1 are the same as those of the embodiment of FIG.

FIG. 6 shows another embodiment of the biasing member 16.
In this embodiment, the biasing member 16 is formed of a rubber O-ring. This O-ring 16 is
4 is urged toward the inner wall surface 3a of the cylinder bore to minimize the blow-by gas leakage path between the inner wall surface 3a of the cylinder bore and the oil ring 14, and at the same time, the blow-by gas formed between the wall surface of the oil ring receiving groove 8 and the oil ring 14. It also acts to seal the leak path. Therefore, the flow path resistance of the blow-by gas leakage path around the oil ring 14 can be further increased.

When the urging member 16 is formed of a rubber O-ring as in the embodiment of FIG. 6, the urging member 16 receives heat from the piston 1 and expands thermally when the engine is operating. Therefore, the urging member 1 is designed so that the sealing action of the oil ring 14 is ensured even during the cold operation.
When the size or the material of 6 is determined, a large urging force acts on the oil ring 14 by the urging member 16 after the completion of the warm-up operation. As a result, the blow-by gas leak path between the oil ring 14 and the cylinder bore inner wall surface 3a can be further reduced.

However, if an excessive urging force acts on the oil ring 14 by the urging member 16 after the completion of the warm-up operation, the frictional resistance between the oil ring 14 and the inner wall surface 3a of the cylinder bore increases. Therefore, the size or material of the urging member 16 may be determined so that an appropriate urging force acts on the oil ring 14 after the completion of the warm-up operation. In this case, since the urging member 16 contracts during the cold operation, the frictional resistance between the oil ring 14 and the inner wall surface 3a of the cylinder bore can be reduced, so that a good engine start or warm-up operation during the cold operation can be ensured. can do.

However, during the cold operation, the oil ring 14
When the frictional resistance between the oil ring 14 and the cylinder bore inner wall surface 3a is reduced, blow-by gas may leak into the crank chamber 5 through the blow-by gas leakage path between the oil ring 14 and the cylinder bore inner wall surface 3a. Therefore, in this case, the second compression ring 13 is provided with an overlapping port as shown in FIG. As a result, the flow path resistance of the leakage path around the second compression ring 13 can be increased, so that the amount of blow-by gas that reaches the inside of the crank chamber 5 can be reduced. After the warm-up operation is completed, for example, the same operation as the embodiment shown in FIG. 1 is obtained.

In the above-described embodiment, the first and second compression rings 9 and 13 are usually provided with the opening 10. However, the first and second compression rings 9 and 13 may be provided with overlapping ports. In particular, the second compression ring 13 may be formed from an annular body that extends continuously without having an abutment.
In the above-described embodiment, the second compression ring 1
Although 3 is made of metal, the second compression ring 13 may be made of resin or fiber composite resin. Further, the urging member 16 is applied to the first and second compression rings 9 and 13 so that
Alternatively, the second compression rings 9 and 13 may be urged toward the cylinder bore inner wall surface 3a. In the above-described embodiment, the compression ring is formed from the pair of compression rings 9 and 13. However, the compression ring may be formed from one compression ring, or may be formed from three or more compression rings. Is also good.

[0035]

In the invention according to claim 1 or 2, according to the present invention, the flow resistance of the blow-by gas leakage path around the compression ring, is made smaller than the flow resistance of the blow-by gas leakage path around the oil ring Compression The blow-by gas leaked through the blow-by gas leak path around the ring can be sealed by an oil ring,
Therefore, the amount of blow-by gas reaching the crank chamber can be reduced. In this case, the pressure difference between the top side and the bottom side of the compression ring is reduced, so that the compression ring tends to flutter. As a result, the frequency of contact of the top surface of the compression ring with the top surface of the compression ring receiving groove increases, so that good heat radiation from the piston to the inner wall surface of the cylinder bore can be ensured.

Furthermore the invention set forth in claim 1, the oil ring, a very large flow resistance of the blow-by gas leakage path around the oil ring because it made without continuously extending annular member having a split end can do. Therefore, the amount of blow-by gas reaching the crank chamber can be further reduced. Claim 2
In Ming, there is also a bias provided in the oil ring receiving groove.
Point the oil ring to the inner surface of the cylinder bore with the member
The oil ring and cylinder
A) The flow path resistance of the blow-by gas leakage path formed between the inner wall surfaces
The resistance can be extremely large. Moreover, the urging member
Is formed from a heat-expandable material, so it is energized during cold operation.
The oil ring and cylinder bore
The frictional resistance between the inner wall surfaces can be reduced. This place
So that both ends of the compression ring overlap
The amount of blow-by gas that reaches the crankcase
Can be further reduced. According to the third aspect of the present invention, since the oil ring is formed from a fiber composite resin having a small coefficient of linear thermal expansion, even when a joint is formed in the oil ring, a blow-by gas leakage path around the oil ring is formed. The flow path resistance can be extremely increased.

According to the fourth aspect of the present invention, since both ends of the oil ring overlap each other, the flow resistance of the blow-by gas leakage path around the oil ring can be extremely increased .

[0038]

According to the fifth aspect of the present invention, since the lubricating oil escape passage is opened in the peripheral surface of the piston between the oil ring receiving groove and the bottom end of the piston, the oil ring always contacts the bottom surface of the oil ring receiving groove. Even in the case where the lubricating oil is removed, excess lubricating oil can be satisfactorily removed. Therefore, the consumption of lubricating oil can be reduced.

[Brief description of the drawings]

FIG. 1 is a partial sectional view of a piston according to an embodiment of the present invention.

FIG. 2 is a partially enlarged perspective view of a normal abutment.

FIG. 3 is a partially enlarged cross-sectional view of the piston, for explaining the operation of the piston shown in FIG. 1;

FIG. 4 is a partially enlarged cross-sectional view of a piston showing another embodiment of the oil ring.

FIG. 5 is a partially enlarged perspective view of an overlapping portion provided in the oil ring of FIG. 4;

FIG. 6 is a partially enlarged sectional view of a piston showing another embodiment of the biasing member.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Piston 3 ... Cylinder bore 4 ... Combustion chamber 5 ... Crank chamber 9 ... 1st compression ring 13 ... 2nd compression ring 14 ... Oil ring 15 ... Lubricating oil release passage 16 ... Biasing member

──────────────────────────────────────────────────続 き Continued on front page (51) Int.Cl. ⁷ Identification code FI F16J 9/16 F16J 9/16 9/28 9/28

Claims (5)

(57) [Claims] 1. A blow-by formed around a compression ring in a piston of an internal combustion engine having at least one metal compression ring and an oil ring arranged on a peripheral surface of the piston in order from the top surface side of the piston. The flow path resistance of the gas leak path is smaller than the flow path resistance of the blow-by gas leak path formed around the oil ring, and the oil ring has an abutment.
And a piston made of a resin-made annular body extending continuously . 2. A blow-by formed around a compression ring in a piston of an internal combustion engine including at least one metal compression ring and an oil ring arranged on a peripheral surface of the piston in order from a top surface side of the piston. The flow path resistance of the gas leakage path is made smaller than the flow path resistance of the blow-by gas leakage path formed around the oil ring, and the piston of the piston that receives the oil ring is turned off.
Oil ring inside cylinder bore inside oil ring receiving groove
An urging member for urging the surface is provided, and the urging member is heated.
Formed from an intumescent material, the compression ring
Fits at least one compression ring
Compression that forms
Make sure both ends of the ring overlap each other after assembly
Piston you. 3. A piston according to claim 1 or 2 the oil ring formed from a fiber composite resin. 4. A piston according to claim 1 or 2 as overlap each other after assembling both ends of the oil ring defining said abutment to form the abutments on the oil ring. 5. A lubricating oil escape passage for letting lubricating oil scraped off by the oil ring escape from the peripheral surface of the piston, and the lubricating oil escape passage is opened in an oil ring receiving groove of the piston for receiving the oil ring. oil ring receiving groove and the piston according to claim 1 or 2 was opened to the piston peripheral surface in between the piston bottom end without.