JP2004353773A - Piston - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piston capable of securing high sealing performance when a compression chamber becomes high pressure and securing small sliding resistance when the compression chamber becomes low pressure. <P>SOLUTION: The piston 1 is provided with a piston body 2 reciprocating inside a cylinder 5 and partitioning the compression chamber 7 between an inner face of the cylinder 5 and the piston body 2, a pressure receiving part 3 arranged on a top part of the piston body 2, and a seal part 4 arranged adjacent to the pressure receiving part 3 and abutted on an inner peripheral face of the cylinder 5. The pressure receiving part 3 is transformed or moved by receiving pressure from the compression chamber 7, and the seal part 4 is energized in the inner peripheral face direction of the cylinder 5 by the transformation or motion of the pressure receiving part 3 and secures the sealing performance. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a piston that reciprocates in a cylinder such as an engine, a reciprocating compressor, a fluid pressure cylinder, and defines a compression chamber between the cylinder and an inner surface of the cylinder.
[0002]
[Prior art]
FIG. 13 shows an axial cross-sectional view of the piston (for example, see Patent Document 1). The piston 100 is arranged in the cylinder 101 so as to be able to reciprocate. The combustion chamber 102 is defined between the top surface of the piston 100 and the inner surface of the cylinder 101. Three rows of ring grooves 103 are formed on the outer peripheral surface of the piston 100. Among them, a compression ring 104 made of carbon steel is installed in each of the two rows of ring grooves 103 in the upper and middle stages. The outer peripheral surface of the compression ring 104 is in contact with the inner peripheral surface of the cylinder 101.
[0003]
FIG. 14 shows an enlarged view of circle B in FIG. In the compression stroke and the combustion stroke, the pressure from the combustion chamber acts on the compression ring 104 as shown by the white arrow in the figure. That is, the compression ring 104 is pressed against the inner peripheral surface of the cylinder 101 by the pressure from the combustion chamber. On the other hand, the pressure from the combustion chamber does not act on the compression ring 104 in the exhaust stroke and the intake stroke. Therefore, in the compression stroke and the combustion stroke, the contact force of the compression ring 104 against the inner peripheral surface of the cylinder 101 is larger than in the exhaust stroke and the suction stroke. In the compression stroke and the combustion stroke, the sealing force of the combustion chamber 102 is ensured by this contact force.
[0004]
Returning to FIG. 13, an oil ring 105 is mounted in the lower ring groove 103. The oil ring 105 scrapes off excess oil from the inner peripheral surface of the cylinder 101. An oil film having an appropriate thickness is formed on the inner peripheral surface of the cylinder 101.
[0005]
[Patent Document 1]
JP-A-2002-115759
[0006]
[Problems to be solved by the invention]
However, conventionally, the contact force of the compression ring 104 in the compression stroke and the combustion stroke has not been much larger than the contact force of the compression ring 104 in the exhaust stroke and the suction stroke. The reason is that, as shown in FIG. 14, the compression ring 104 is pressed against not only the inner peripheral surface of the cylinder 101 but also the ring groove lower surface 106 by the pressure from the combustion chamber. That is, the compression ring 104 was in contact with the inner peripheral surface of the cylinder 101 while sliding on the ring groove lower surface 106. Therefore, the contact force on the inner peripheral surface of the cylinder 101 is reduced by the sliding resistance with the ring groove lower surface 106.
[0007]
If the contact force against the inner peripheral surface of the cylinder 101 is small, the sealing performance between the compression ring 104 and the inner peripheral surface of the cylinder 101 is deteriorated, and blow-by gas may leak from this gap.
[0008]
Therefore, conventionally, the compression ring 104 has been brought into contact with the inner peripheral surface of the cylinder 101 with a relatively large force from the beginning when the piston 100 is assembled to the cylinder 101. And the contact force of the compression ring 104 in the compression stroke and the combustion stroke was ensured.
[0009]
However, in this case, the contact force of the compression ring 104 in the exhaust stroke and the suction stroke must be increased. That is, the contact force of the compression ring 104 against the inner peripheral surface of the cylinder 101 was relatively large during the entire stroke of compression, combustion, exhaust, and suction. When the piston 100 reciprocates in the cylinder 101, the compression ring 104 is in sliding contact with the cylinder inner peripheral surface 101. The sliding resistance at this time is proportional to the contact force of the compression ring 104. Therefore, conventionally, the sliding resistance of the compression ring 104 was large. For this reason, the compression ring 104 and the inner peripheral surface of the cylinder 101 were easily worn. Further, the output of the engine may be reduced.
[0010]
The piston of the present invention has been completed in view of the above problems. Therefore, according to the present invention, when the compression chamber (corresponding to the combustion chamber 102 in FIG. 13) such as the compression stroke and the combustion stroke has a high pressure, high sealing performance can be ensured, and the compression chamber such as the exhaust stroke and the suction stroke has a low pressure. It is an object of the present invention to provide a piston capable of securing a small sliding resistance when the above condition is satisfied.
[0011]
[Means for Solving the Problems]
(1) In order to solve the above problems, a piston according to the present invention reciprocates in a cylinder to partition a compression chamber between the piston and an inner surface of the piston, and a pressure receiving portion disposed on the top of the piston body. And a seal portion disposed adjacent to the pressure receiving portion and abutting on the inner peripheral surface of the cylinder, wherein the pressure receiving portion deforms or moves by receiving a pressure from the compression chamber, and the seal portion is The pressure receiving portion is urged in the direction of the inner peripheral surface of the cylinder by the deformation or movement of the pressure receiving portion to secure the sealing property.
[0012]
That is, the piston of the present invention includes the pressure receiving portion and the seal portion. When the pressure in the compression chamber becomes high (for example, in a compression stroke and a combustion stroke in an engine), the pressure receiving portion transmits the pressure from the compression chamber to the seal portion. The seal portion is in contact with the inner peripheral surface of the cylinder. The seal portion converts the pressure transmitted from the pressure receiving portion into a contact force on the inner peripheral surface of the cylinder. By adding this conversion, the contact force of the seal portion on the inner peripheral surface of the cylinder becomes relatively large. On the other hand, when the pressure in the compression chamber becomes low (for example, in an engine, an exhaust stroke and a suction stroke), the pressure in the compression chamber hardly acts on the pressure receiving portion. For this reason, the contact force of the seal portion on the inner peripheral surface of the cylinder becomes relatively small.
[0013]
As described above, according to the piston of the present invention, it is possible to increase the difference between the contact force of the seal portion when the compression chamber has a high pressure and the contact force of the seal portion when the compression chamber has a low pressure. Therefore, it is possible to reduce the sliding resistance against the inner peripheral surface of the cylinder when the pressure in the compression chamber is low, while ensuring high sealing performance when the pressure in the compression chamber is high. Therefore, according to the piston of the present invention, the seal portion and the inner peripheral surface of the cylinder are less likely to be worn.
[0014]
(2) Preferably, a ring step is formed on an outer peripheral edge of a top portion of the piston body, and an inner peripheral edge of the pressure receiving portion is fixed to the ring step edge, and a ring groove is formed between the inner peripheral edge and the ring step. Wherein the seal portion is an elastic seal ring which is mounted in the ring groove and abuts on the inner peripheral surface of the cylinder, wherein the pressure receiving ring receives the pressure from the compression chamber and receives the pressure. A configuration in which the elastic seal ring is elastically deformed in an inward direction of the ring groove, and the elastic seal ring is urged in the inner circumferential surface direction of the cylinder by the elastic deformation of the pressure receiving ring to reduce the groove width of the ring groove, thereby ensuring sealing performance It is better to do.
[0015]
The inner peripheral edge of the pressure receiving ring is fixed to the ring step edge. On the other hand, the outer peripheral edge of the pressure receiving ring is open. That is, the pressure receiving ring is fixed in a cantilever cross section. A ring groove is defined between the pressure receiving ring and the ring step. An elastic seal ring is mounted in the ring groove. The elastic seal ring is in contact with the inner peripheral surface of the cylinder.
[0016]
When the pressure in the compression chamber becomes high, the pressure receiving ring bends in the ring groove direction due to the pressure from the compression chamber. Due to this bending, the groove width of the ring groove is reduced. When the groove width is reduced, the elastic seal ring is deformed just to protrude from the ring groove. Due to this deformation, the contact force of the elastic seal ring against the inner peripheral surface of the cylinder becomes relatively large. On the other hand, when the pressure in the compression chamber becomes low, the pressure from the compression chamber hardly acts on the pressure receiving ring. For this reason, the groove width of the ring groove does not easily become narrow. Therefore, the contact force of the elastic seal ring against the inner peripheral surface of the cylinder becomes relatively small.
[0017]
According to this configuration, with a relatively simple structure, it is possible to achieve both high sealing performance when the compression chamber is at high pressure and small sliding resistance when the compression chamber is at low pressure.
[0018]
Further, no abutment gap is formed in the elastic seal ring. Therefore, at least one of the compression rings becomes unnecessary. For this reason, the number of parts of the piston is reduced. Also, the number of assembling steps is reduced.
[0019]
(3) Preferably, a configuration is adopted in which a seal convex portion that is in contact with the inner peripheral surface of the cylinder is disposed on an outer peripheral edge of the seal portion. According to this configuration, when the pressure in the compression chamber becomes low, the seal projection makes line contact with the inner peripheral surface of the cylinder. For this reason, the sliding resistance is further reduced. On the other hand, when the pressure in the compression chamber is high, the seal convex portion is deformed so as to be crushed and pressed against the inner peripheral surface of the cylinder. That is, the state of contact of the seal projection with the inner peripheral surface of the cylinder changes from line contact to surface contact. For this reason, not only does the contact force of the seal projection against the cylinder inner peripheral surface increase, but also the contact area, that is, the seal area increases. Therefore, the sealing performance is further improved.
[0020]
(4) Preferably, the seal portion is an elastic seal plate covering a top portion of the piston main body, and the pressure receiving portion covers the elastic seal plate and slides in the piston reciprocating direction with respect to the piston main body. The pressure receiving plate is slidably moved in the direction of the piston body by receiving the pressure from the compression chamber, and the elastic seal plate is moved by the sliding movement of the pressure receiving plate. It is preferable that the clearance between the receiving portion and the piston main body is reduced so as to be urged toward the inner peripheral surface of the cylinder to secure the sealing property.
[0021]
That is, in this configuration, the elastic seal plate and the pressure receiving plate are mounted on the top of the piston main body in a stacked manner. When the pressure from the compression chamber is applied to the pressure receiving plate when the pressure in the compression chamber becomes high, the pressure receiving plate slides toward the piston body. For this reason, the width of the gap between the pressure receiving plate and the piston body is reduced. An elastic seal plate is interposed in this gap. Therefore, the elastic seal plate is pressed against the inner peripheral surface of the cylinder.
[0022]
According to this configuration, the pressure receiving plate is mounted so as to cover the top of the piston body. Therefore, the pressure receiving area of the pressure receiving plate (the area receiving the pressure from the compression chamber) is relatively large. Therefore, the pressure from the compression chamber can be used more efficiently.
[0023]
Further, according to this configuration, the pressure receiving plate itself slides to urge the elastic seal plate. Therefore, the pressure receiving plate itself is not required to have flexibility. Therefore, the degree of freedom in selecting the material of the pressure receiving plate is relatively high.
[0024]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment using a piston of the present invention for an engine will be described.
[0025]
(1) First embodiment
First, the configuration of the piston of the present embodiment will be described. FIG. 1 shows an assembly diagram of the piston of the present embodiment. FIG. 2 shows a perspective view of the piston of the present embodiment. FIG. 3 shows an exploded perspective view of the piston of the present embodiment.
[0026]
As shown in these figures, the piston 1 is arranged in a cylinder 5 of the engine. A combustion chamber 7 is defined between the top surface of the piston 1 and the inner surface of the cylinder 5. The combustion chamber 7 is included in the compression chamber of the present invention. The piston 1 is pivotally supported at the upper end of the connecting rod 6. The lower end of the connecting rod 6 is pivotally supported by a crank pin (not shown). The piston 1 includes a piston main body 2, a pressure receiving ring 3, and an elastic seal ring 4. The piston body 2 is made of an aluminum alloy, and has a cylindrical shape with a bottom opening downward, that is, a cup shape. A boss 21 is formed on the body of the piston body 2 to protrude inward. The boss 21 is pivotally supported on the upper end of the connecting rod 6.
[0027]
FIG. 4 is a sectional view taken along line II of FIG. FIG. 5 shows an enlarged view of circle A in FIG. FIG. 5 shows the state of the piston in the suction stroke and the exhaust stroke.
[0028]
As shown in these figures, a ring step 20 having an L-shaped cross section is formed on the outer peripheral edge of the top of the piston body 2. The pressure receiving ring 3 is made of spring steel. The inner peripheral edge of the pressure receiving ring 3 is welded to the edge of the ring step 20. The pressure receiving ring 3 covers the ring step 20 from above. A ring groove 22 opening toward the outer peripheral side is defined between the lower surface of the pressure receiving ring 3 and the ring step 20. The elastic seal ring 4 is made of silicone rubber. The elastic seal ring 4 is mounted around the ring groove 22 by outsert molding. The outer peripheral surface of the elastic seal ring 4 is in contact with the inner peripheral surface of the cylinder 5.
[0029]
Next, the movement of the piston according to the present embodiment will be described. FIG. 6 is an enlarged view of the vicinity of the elastic seal ring in the compression stroke and the combustion stroke. In the figure, as indicated by a white arrow C, the pressure from the combustion chamber 7 (compression pressure accompanying the rise of the piston in the compression stroke, combustion pressure due to mixture combustion in the combustion stroke) is applied to the pressure receiving ring 3 from above. Join. The inner peripheral edge of the pressure receiving ring 3 is fixed. On the other hand, the outer peripheral edge of the pressure receiving ring 3 is open in a cantilever cross section. For this reason, the outer peripheral portion of the pressure receiving ring 3 bends downward with the fixed inner peripheral edge as a fulcrum. When the pressure receiving ring 3 bends, the vertical groove width of the ring groove 22 decreases. For this reason, the elastic seal ring 4 that has been disposed over the entire groove width is deformed so as to be pushed out from the inside of the ring groove 22 toward the outer peripheral side, that is, toward the inner peripheral surface of the cylinder 5, as indicated by the outline arrow D. Due to the deformation of the elastic seal ring 4, the contact force of the elastic seal ring 4 against the inner peripheral surface of the cylinder 5 increases.
[0030]
As described above, in the compression stroke and the combustion stroke, the pressure from the upper direction to the lower direction is converted by the pressure receiving ring 3 and the elastic seal ring 4 into the contact force from the inner circumference to the outer circumference. The contact force of the elastic seal ring 4 with respect to the inner peripheral surface of the cylinder 5 is increased by the amount of the conversion.
[0031]
On the other hand, as shown in FIG. 5 described above, in the exhaust stroke and the suction stroke, no upward-downward pressure is applied to the pressure receiving ring 3 from the combustion chamber 7. Therefore, the elastic seal ring 4 deformed in the compression stroke and the combustion stroke is restored by its own elastic restoring force. Specifically, it expands upward. This expansion, together with the elastic restoring force of the pressure receiving ring 3 itself, also restores the pressure receiving ring 3. Specifically, the outer peripheral portion of the pressure receiving ring 3 rises. Further, as the elastic seal ring 4 expands, the contact force of the elastic seal ring 4 against the inner peripheral surface of the cylinder 5 decreases. Therefore, the contact force of the elastic seal ring 4 on the inner peripheral surface of the cylinder 5 in the exhaust stroke and the suction stroke is smaller than the contact force of the elastic seal ring 4 on the inner peripheral surface of the cylinder 5 in the compression stroke and the combustion stroke.
[0032]
As described above, in the piston 1 of the present embodiment, the operation of bending the pressure receiving ring 3 → deforming the elastic seal ring 4 → restoring the elastic seal ring 4 → restoring the pressure receiving ring 3 is repeatedly performed.
[0033]
Next, effects of the piston of the present embodiment will be described. According to the piston 1 of this embodiment, the difference between the contact force of the elastic seal ring 4 in the compression stroke and the combustion stroke and the contact force of the elastic seal ring 4 in the exhaust stroke and the suction stroke can be increased. Therefore, the sliding resistance against the inner peripheral surface of the cylinder 5 can be reduced in the exhaust stroke and the suction stroke while ensuring high sealing performance in the compression stroke and the combustion stroke. Therefore, according to the piston 1 of the present embodiment, the inner peripheral surface of the elastic seal ring 4 and the cylinder 5 is less likely to be worn. In addition, the possibility that the output of the engine will decrease is small.
[0034]
Further, according to the piston 1 of the present embodiment, the pressure receiving ring 3 and the elastic seal ring 4 can achieve both high sealing performance in the compression stroke and the combustion stroke and small sliding resistance in the exhaust stroke and the suction stroke. it can. That is, with a relatively simple structure, both high sealing performance and small sliding resistance can be achieved.
[0035]
Further, according to the piston 1 of the present embodiment, the compression ring 104 and the oil ring 105 of FIG. That is, the elastic seal ring 4 has both the function of a compression ring to secure the sealing performance and the function of an oil ring to form an appropriate oil film. Therefore, the number of parts of the piston 1 is reduced. Also, the number of assembling steps is reduced.
[0036]
The elastic seal ring 4 is not made of metal but made of silicon rubber. Therefore, the elastic seal ring 4 is lightweight, and the inertial force of the elastic seal ring 4 is small. Therefore, even when the piston 1 reciprocates in the cylinder 5 at a high speed, the followability of the elastic seal ring 4 to the ring groove 22 is high.
[0037]
(2) Second embodiment
The difference between this embodiment and the first embodiment is that a seal projection is arranged on the outer peripheral edge of the elastic seal ring. Therefore, only the differences will be described here.
[0038]
FIG. 7 is an enlarged view of the vicinity of the elastic seal ring in the exhaust stroke and the suction stroke. Parts corresponding to those in FIG. 5 are denoted by the same reference numerals. As shown in the figure, the outer peripheral surface of the elastic seal ring 4 has a tapered shape that narrows from downward to upward. That is, at the lower end of the outer periphery of the elastic seal ring 4, the seal projection 40 is formed. In the exhaust stroke and the suction stroke, only the tip of the seal projection 40 contacts the inner peripheral surface of the cylinder 5. That is, the seal projection 40 is in line contact with the inner peripheral surface of the cylinder 5.
[0039]
FIG. 8 is an enlarged view of the vicinity of the elastic seal ring in the compression stroke and the combustion stroke. Parts corresponding to those in FIG. 6 are denoted by the same reference numerals. In the compression stroke and the combustion stroke, the direction of the pressure from the combustion chamber 7 is changed from the upper direction to the lower direction by the pressure receiving ring 3 and the elastic seal ring 4 from the inner circumference to the outer circumference. Due to the converted pressure, the seal convex portion 40 is deformed so as to be crushed and pressed against the inner peripheral surface of the cylinder 5.
[0040]
The piston 1 of the present embodiment has the same effect as the piston of the first embodiment. According to the piston 1 of the present embodiment, the seal projection 40 is in line contact with the inner peripheral surface of the cylinder 5 during the exhaust stroke and the suction stroke. For this reason, the sliding resistance is further reduced. In addition, the seal projection 40 has a tapered shape that narrows from downward to upward. For this reason, surplus oil can be scraped off relatively easily from the inner peripheral surface of the cylinder 5. Therefore, an oil film having an appropriate thickness can be formed on the inner peripheral surface of the cylinder 5.
[0041]
Further, according to the piston 1 of the present embodiment, in the compression stroke and the combustion stroke, the seal projection 40 is deformed so as to be crushed and pressed against the inner peripheral surface of the cylinder 5. That is, the state of contact of the seal projection 40 with the inner peripheral surface of the cylinder 5 changes from line contact to surface contact. For this reason, not only does the contact force of the seal projection 40 against the inner peripheral surface of the cylinder 5 increase, but also the contact area, that is, the seal area increases. Therefore, the sealing performance is further improved.
[0042]
(3) Third embodiment
The difference between the present embodiment and the second embodiment is that a chamfered portion is formed at the step edge of the ring. Therefore, only the differences will be described here.
[0043]
FIG. 9 is an enlarged view of the vicinity of the elastic seal ring in the exhaust stroke and the suction stroke. Parts corresponding to those in FIG. 7 are denoted by the same reference numerals. FIG. 10 is an enlarged view of the vicinity of the elastic seal ring in the compression stroke and the combustion stroke. Parts corresponding to those in FIG. 8 are denoted by the same reference numerals. As shown in these figures, a chamfered portion 23 is formed at the edge of the ring step 20.
[0044]
The piston 1 of the present embodiment has the same effect as the piston of the second embodiment. Further, a chamfered portion 23 is formed at the edge of the ring step 20 of the piston 1 of the present embodiment. In the compression stroke and the combustion stroke, the pressure receiving ring 3 bends along the radius of curvature of the chamfered portion 23. For this reason, the pressure receiving ring 3 is easily bent downward. Therefore, the seal projection 40 of the elastic seal ring 4 is further deformed. As described above, according to the piston 1 of the present embodiment, the contact force and the seal area of the seal projection 40 in the compression stroke and the combustion stroke are further increased. For this reason, the sealing performance is further improved.
[0045]
(4) Fourth embodiment
The difference between the present embodiment and the first embodiment is that an oil ring is mounted around the piston body. Therefore, only the differences will be described here.
[0046]
FIG. 11 shows an axial sectional view of the piston of the present embodiment. Parts corresponding to those in FIG. 4 are denoted by the same reference numerals. As shown in the figure, an oil ring groove 24 is formed in the body of the piston body 2. The oil ring 8 is mounted in the oil ring groove 24.
[0047]
The piston 1 of the present embodiment has the same effect as the piston of the first embodiment. Further, the piston 1 of the present embodiment includes an oil ring 8. For this reason, the surplus oil can be more reliably scraped off from the inner peripheral surface of the cylinder 5. Therefore, an oil film having an appropriate thickness can be formed on the inner peripheral surface of the cylinder 5.
[0048]
(5) Fifth embodiment
The difference between the present embodiment and the first embodiment is that a pressure receiving plate is disposed instead of the pressure receiving portion ring. Another point is that the pressure receiving plate moves, not deforms, due to the pressure from the combustion chamber. Another difference is that an elastic seal plate is provided instead of the elastic seal ring. Therefore, only the differences will be described here.
[0049]
FIG. 12 shows an axial sectional view of the piston of the present embodiment. Parts corresponding to those in FIG. 4 are denoted by the same reference numerals. As shown in the figure, a pressure receiving plate 30 and an elastic seal plate 41 are laminated on the top of the piston body 2. The pressure receiving plate 30 is made of spring steel and has a disk shape. A bolt portion 300 protrudes from the lower surface of the pressure receiving plate 30.
[0050]
The elastic seal plate 41 is made of silicone rubber and has a disk shape. At substantially the center of the elastic seal plate 41, a through hole 410 is formed. The outer peripheral surface of the elastic seal plate 41 is in contact with the inner peripheral surface of the cylinder 5. Further, a bolt locking hole 200 is formed in the top of the piston body 2.
[0051]
The bolt part 300 penetrates the through hole 410 and the bolt part locking hole 200. A nut 301 made of an aluminum alloy is screwed to the tip of the bolt part 300.
[0052]
In the compression stroke and the combustion stroke, the pressure from the combustion chamber 7 causes the entire pressure receiving plate 30 to slide downward. Due to this sliding movement, the elastic seal plate 41 is deformed so as to be crushed and pressed against the inner peripheral surface of the cylinder 5.
[0053]
On the other hand, in the exhaust stroke and the suction stroke, no upward-downward pressure is applied to the pressure receiving plate 30. Therefore, the elastic seal plate 41 deformed in the compression stroke and the combustion stroke is restored by its own elastic restoring force. Specifically, it expands upward. Due to this expansion, the pressure receiving plate 30 slides up. Further, as the elastic seal plate 41 expands, the contact force of the elastic seal plate 41 on the inner peripheral surface of the cylinder 5 decreases.
[0054]
As described above, in the piston 1 of the present embodiment, the movement of sliding down the pressure receiving plate 30 → deforming the elastic seal plate 41 → restoring the elastic seal plate 41 → sliding up the pressure receiving plate 30 is repeatedly performed.
[0055]
The piston 1 of the present embodiment has the same effect as the piston of the first embodiment. Further, according to the piston 1 of the present embodiment, the pressure receiving plate 30 is mounted over the entire top surface of the piston main body 2. For this reason, the pressure receiving area of the pressure receiving plate 30 (the area receiving the pressure from the combustion chamber 7) is larger than the pressure receiving area of the pressure receiving ring 3 in FIG. Therefore, according to the piston 1 of the present embodiment, the pressure from the combustion chamber 7 can be used more efficiently.
[0056]
Further, according to the piston 1 of the present embodiment, it is not necessary to form the ring step 20 in the piston main body 2 as shown in FIG. For this reason, the manufacturing cost of the piston main body 2 is reduced.
[0057]
Further, according to the piston 1 of the present embodiment, the elastic seal plate 41 is locked by the bolt portion 300 at substantially the center in the radial direction. For this reason, the possibility that the elastic seal portion 40 falls off from the piston main body 2 during the reciprocating movement of the piston 1 is small.
[0058]
Further, according to the piston 1 of the present embodiment, the pressure receiving plate 30 is locked by the nut 301. For this reason, the possibility that the pressure receiving plate 30 falls off from the piston body 2 during the reciprocating movement of the piston 1 is small.
[0059]
Further, according to the piston 1 of the present embodiment, the pressure receiving plate 30 itself slides. Therefore, the pressure receiving plate 30 is not required to have flexibility. Therefore, the pressure receiving plate 30 has a higher degree of freedom in material selection than the pressure receiving ring 3 of FIG.
[0060]
(6) Other
The embodiment of the piston of the present invention has been described above. However, the embodiments are not particularly limited to the above embodiments. Various modifications and improvements that can be made by those skilled in the art are also possible.
[0061]
For example, in the above embodiment, the piston body 2 made of an aluminum alloy is used, but a piston body made of, for example, PI (polyimide) or PPS (polyphenylene sulfide) may be used. Thus, the weight of the piston body 2 can be reduced.
[0062]
Further, in the above embodiment, the pressure receiving ring 3 and the pressure receiving plate 30 made of spring steel are used, but a pressure receiving ring and a pressure receiving plate made of, for example, carbon steel or stainless steel may be used.
[0063]
In the above embodiment, the elastic seal ring 4 and the elastic seal plate 41 made of silicon rubber are used. However, an elastic seal ring or an elastic seal plate made of modified PPS or fluorine rubber may be used.
[0064]
The combination of the material of the pressure receiving ring 3 and the material of the elastic seal ring 4 determines the conversion efficiency when converting the pressure from the compression chamber (combustion chamber 7) into the contact force against the inner peripheral surface of the cylinder 5. Contributes. Therefore, the material of the pressure receiving ring 3 and the material of the elastic seal ring 4 may be combined in accordance with a desired contact force. Similarly, the material of the pressure receiving plate 30 and the material of the elastic seal plate 41 may be combined.
[0065]
In the second and third embodiments, the tapered seal projection 40 is arranged, but a step-shaped or curved seal projection may be arranged. Further, a plurality of seal projections may be arranged.
[0066]
Further, in the above-described embodiment, the piston of the present invention is used for an engine. In this case, the heat resistance required for the piston is relatively low. Therefore, the degree of freedom in selecting the material of the piston is increased.
[0067]
【The invention's effect】
According to the present invention, it is possible to provide a piston that can secure a high sealing property when the compression chamber has a high pressure and can secure a small sliding resistance when the compression chamber has a low pressure.
[Brief description of the drawings]
FIG. 1 is an assembly diagram of a piston according to a first embodiment.
FIG. 2 is a perspective view of a piston according to the first embodiment.
FIG. 3 is an exploded perspective view of a piston according to the first embodiment.
FIG. 4 is a sectional view taken along a line II of FIG. 2;
FIG. 5 is an enlarged view of circle A in FIG. 4;
FIG. 6 is an enlarged view of the vicinity of an elastic seal ring in a compression stroke and a combustion stroke of the piston of the first embodiment.
FIG. 7 is an enlarged view of the vicinity of an elastic seal ring in an exhaust stroke and a suction stroke of the piston according to the second embodiment.
FIG. 8 is an enlarged view of the vicinity of an elastic seal ring in a compression stroke and a combustion stroke of the piston according to the second embodiment.
FIG. 9 is an enlarged view of the vicinity of an elastic seal ring in an exhaust stroke and a suction stroke of the piston according to the third embodiment.
FIG. 10 is an enlarged view of the vicinity of an elastic seal ring in a compression stroke and a combustion stroke of the piston according to the third embodiment.
FIG. 11 is an axial sectional view of a piston according to a fourth embodiment.
FIG. 12 is an axial sectional view of a piston according to a fifth embodiment.
FIG. 13 is an axial sectional view of a conventional piston.
FIG. 14 is an enlarged view of FIG.
[Explanation of symbols]
1: piston, 2: piston body, 20: ring step, 200: bolt locking hole, 21: boss, 22: ring groove, 23: chamfered part, 24: oil ring groove, 3: pressure receiving ring, 30: pressure receiving plate, 300: bolt portion, 301: nut, 4: elastic seal ring, 40: seal convex portion, 41: elastic seal plate, 410: through hole, 5: cylinder, 6: connecting rod, 7: combustion chamber (Compression chamber), 8: oil ring.

Claims (4)

A piston body reciprocating in a cylinder and defining a compression chamber between the cylinder and an inner surface of the cylinder, a pressure receiving portion disposed at the top of the piston body, and an inner periphery of the cylinder disposed adjacent to the pressure receiving portion; And a seal portion abutting the surface,
The pressure receiving portion is deformed or moved by receiving a pressure from the compression chamber, and the seal portion is urged in the direction of the inner circumferential surface of the cylinder by the deformation or movement of the pressure receiving portion to secure the sealing property. And the piston. A ring step is formed on the top outer peripheral edge of the piston body,
The pressure receiving portion is a pressure receiving ring having an inner peripheral edge fixed to the ring step edge and defining a ring groove with the ring step,
The seal portion is an elastic seal ring that is mounted in the ring groove and abuts on the inner peripheral surface of the cylinder,
The pressure receiving ring is elastically deformed inwardly of the ring groove by receiving pressure from the compression chamber, and the elastic seal ring is elastically deformed by the pressure receiving ring so that the groove width of the ring groove is reduced. The piston according to claim 1, wherein the piston is urged in an inner circumferential direction to secure a sealing property. 2. The piston according to claim 1, wherein a seal protruding portion that is in contact with the inner peripheral surface of the cylinder is disposed on an outer peripheral edge of the seal portion. 3. The seal portion is an elastic seal plate that covers a top portion of the piston body,
The pressure receiving portion is a pressure receiving plate that covers the elastic seal plate and is slidably engaged with the piston body in a reciprocating direction of the piston.
The pressure receiving plate slides in the direction of the piston body under the pressure from the compression chamber, and the elastic seal plate has a small gap width between the pressure receiving portion and the piston body due to the sliding movement of the pressure receiving plate. The piston according to claim 1, wherein the piston is urged in the direction of the inner circumferential surface of the cylinder to secure sealing properties.

Images