CA1175312A - Piston for an internal combustion engine - Google Patents
Piston for an internal combustion engineInfo
- Publication number
- CA1175312A CA1175312A CA000381026A CA381026A CA1175312A CA 1175312 A CA1175312 A CA 1175312A CA 000381026 A CA000381026 A CA 000381026A CA 381026 A CA381026 A CA 381026A CA 1175312 A CA1175312 A CA 1175312A
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- Canada
- Prior art keywords
- piston
- set forth
- piston rings
- lubricant oil
- groove
- Prior art date
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- Pistons, Piston Rings, And Cylinders (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
An improved sealing structure of the piston for an internal combustion engine, in which two piston rings are disposed within a groove freely movable with respect to one another and with respect to the groove. One of the piston rings is adapted to introduce lubricant oil into the groove during the piston up-stroke and the other is adapted to introduce the oil into the groove in the piston down-stroke. The piston rings reduce the space therebetween to force the lubricant oil in the groove in to the space between the piston ring and the cylinder wall.
An improved sealing structure of the piston for an internal combustion engine, in which two piston rings are disposed within a groove freely movable with respect to one another and with respect to the groove. One of the piston rings is adapted to introduce lubricant oil into the groove during the piston up-stroke and the other is adapted to introduce the oil into the groove in the piston down-stroke. The piston rings reduce the space therebetween to force the lubricant oil in the groove in to the space between the piston ring and the cylinder wall.
Description
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PISTON FOR AN INTERNAL COMBUSTION ENGI~E
BAC~GROUND OF T~E~ INVENTION
The present invention relates generally to a piston for an internal combustion engine. More specifically, the invention relates to an improvement in the sealing structure of the piston for sealing between the piston and the cylinder wall of the engine cylinder.
It has been known to provide a piston ring onto the periphery of the piston. Generally, the piston ring is received within a circumferential groove of the piston and serves for sealing between the piston and the cylinder wall of the engine cylinder so that blow-by is prevented.
Usually, two piston rings are used on the piston to reduce the pressure drop across each ring. An oil-control ring preventing too much lubricant oil from working up into the combustion chamber is also mounted on the periphery of the piston.
As is well known, the piston ring is mounted on the piston in a plane perpendicular to the piston axis.
; Thus, the frictional force applied to the piston ring corresponding to the motion of the piston is directed substantially in the axial direction. In this result, the piston and the piston ring move up and down together. The piston ring is normally prevented from moving in the circumferential direction with respect to the cylinder wall.
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Further, the relative speed of the piston ring with respect to the cylinder wall becomes zero at the points of the piston stroke adjacent the top and bottom stops. As theoretically apparent, this leads to disadvantageous for establishing lubricant oil layer on the cylinder wall. Also, the piston is subjected to the high heat of combustion and high pressure of the compressed mixture at the top stop of the piston stroke. This will cause the piston ring to be urged toward the cylinder wall with a substantial force. As a result, in the conventional sealing structure of the piston, the lubricant oil layer may not established around the top and bottom dead centers of the piston stroke. This tends to cause a large frictional force between the piston ring and the cylinder wall to decrease the engine output and thereby degrade the fuel economy, particularly in low load conditions of the engine operation.
SUMMARY_OF T~E INVENTION
Therefore, it is an object of the present
PISTON FOR AN INTERNAL COMBUSTION ENGI~E
BAC~GROUND OF T~E~ INVENTION
The present invention relates generally to a piston for an internal combustion engine. More specifically, the invention relates to an improvement in the sealing structure of the piston for sealing between the piston and the cylinder wall of the engine cylinder.
It has been known to provide a piston ring onto the periphery of the piston. Generally, the piston ring is received within a circumferential groove of the piston and serves for sealing between the piston and the cylinder wall of the engine cylinder so that blow-by is prevented.
Usually, two piston rings are used on the piston to reduce the pressure drop across each ring. An oil-control ring preventing too much lubricant oil from working up into the combustion chamber is also mounted on the periphery of the piston.
As is well known, the piston ring is mounted on the piston in a plane perpendicular to the piston axis.
; Thus, the frictional force applied to the piston ring corresponding to the motion of the piston is directed substantially in the axial direction. In this result, the piston and the piston ring move up and down together. The piston ring is normally prevented from moving in the circumferential direction with respect to the cylinder wall.
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Further, the relative speed of the piston ring with respect to the cylinder wall becomes zero at the points of the piston stroke adjacent the top and bottom stops. As theoretically apparent, this leads to disadvantageous for establishing lubricant oil layer on the cylinder wall. Also, the piston is subjected to the high heat of combustion and high pressure of the compressed mixture at the top stop of the piston stroke. This will cause the piston ring to be urged toward the cylinder wall with a substantial force. As a result, in the conventional sealing structure of the piston, the lubricant oil layer may not established around the top and bottom dead centers of the piston stroke. This tends to cause a large frictional force between the piston ring and the cylinder wall to decrease the engine output and thereby degrade the fuel economy, particularly in low load conditions of the engine operation.
SUMMARY_OF T~E INVENTION
Therefore, it is an object of the present
2~ invention to provide a piston having a sealing structure which effectively supplies lubricant oil between the piston ring and the cylinder wall and thus prevents large frictional forces between the piston ring and the cylinder wall, particularly at the point of the piston stroke adjacent the top dead center.
To accomplish the above-mentioned and other objects, there is provided an improved sealing structure ~ 17~312 for the piston for the internal combustion engine, in which two piston rings are disposed within a groove in a freely mov-~ble position with respect to one another and with respect to the groove. The piston rings scrape off the lubricant oil constructing the lubricant oil layer on the cylinder wall to introduce the same into a space therebetween during the expan-sion and compression piston strokes. Due to the substantially high gas pressure applied adjacent to the top dead center. The piston rings reduces the space therebetween to force the lubri-cant oil out from between the piston rings to the sliding clearance between the piston ring and the cylinder wall.
In accordance with one aspect of the present invention, there is provided an improved sealing structure for a piston of an internal combustion engine comprising: a piston formed with a plurality of grooves on the periphery thereof, and said piston including means for providing a lubricant oil to esta-blish a lubricant oil layer between said piston and cylinder wall of the engine cylinder; an oil-control ring, mounted in the groove in the lowermost position in said grooves; and a pair of piston rings disposed in the uppermost groove, being spaced apart from each other and movable independently of each other with respect to one another and with respect to said cylinder wall.
In another aspect, there is provided an improvement in a sealing structure for a piston of an internal combustion en-gine comprising: a piston disposed within an engine cylinder for reciprocation therewithin and being formed with first and second grooves on the peripherv thereof and e~tending circum-ferentially; an oil-control ring mounted on said second groove to control the amount of lubricant oil to be supplied between the piston and the cylinder wall of the engine cylinder; and a pair of piston rings disposed within the upyermost first groove and bein~ spaced from each other, each of said piston rings is so constructed as to be freely movable independently , -~, ~
~ 175312 of each other within said uppermost first groove in vertical direction, and each of said piston rings being variable of the diametPr thereof to var~ the clearance defined between said cylinder wall depending upon the pressure applied thereto.
In a further aspect of the invention, an improvement in a sealing structure for a piston of an internal combustion engine comprises: a piston disposed within an engine cylin-der for reciprocation therewithin and being formed with first and second grooves on the periphery thereof and extending circumferentially; an oil-control ring mounted on said second groove to control the amount of lubricant oil to be supplied between the piston and the cylinder all of the engine cylin-der; and a pair of piston rings disposed within the uppermost first groove and being spaced apart from each other, each of said piston being of size for free movement in said first groove in the vertical direction and defining therebetween a space to introduce lubricant oil during the piston stro~e, and the space between said piston rings being variable accord-ing to the relative position of the piston rings depending upon the lubricant oilpressure a~plied thereto so that thelubricant oil is introduced into sàid space as a pressure in a combustion chamber is relatively low and is pushed out as reducing said space by increasing of said pressure in the combustion chamber for establishmentof the lubricantoil layeron saidcylinder wall.
BRIEF DESCRIPTION OF THE DRAWINGS
. _ The present invention will be more fully understood from the detailed description given herebelow and from the ac-companyins drawings of the preferred embodiment of the present invention, which, however, should not be understood as limitive to the invention but are for elucidation and explanation only.
In the drawings:
~ 17~312 Fig. 1 is a longit~dinal section of an engine cylin-der including the first embodiment of a piston according to the present invention;
Fig. 2 is an enlarged section of the piston of ~ig. 1 showing the compression, stroke of the piston;
Fig. 3 is a similar view to Fig. 2 but showing the expansion stroke of the piston;
Fig. 4 is a further enlarged section showing the function of the sealing structure according to the first em-bodiment;
Fig. 5 is a section of the second embodiment of the piston according to the present invention, which illustrates the piston as in the compression stroke;
Fig. 6 is a similar view to Fig. 5 but showing the expansion stroke of the piston;
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~ 17~312 Fig. 7 is an enlarged section of the piston of Fig. 5 showing function of the sealing structure adjacent the top stop in the expansion stroke;
Fig. 8 is a section of the third embodiment of the piston according to the present invention, in which the piston is in the compression stroke;
Fig. 9 is a similar view to Fig. 8 but showing the expansion stroke of the piston;
~ ig. 10 is an enlarged section of the piston of Fig. 5 showing the function of the sealing structure adjacent the top dead center in the expansion stroke;
Figs. 11 to 14 are enlarged sections respectively showing variations of the sealing structure of the piston of Fig. 9.
It should be noted that the section of the piston ring, the space between the piston ring and the groove of the piston and so on are exaggerated for better understanding.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to the drawings, particularly to Fig. 1, there is illustrated an engine cylinder 10 in which a piston 12 is disposed in a slidable position. The piston 12 is constructed as a well known structure and has grooves 14, 16 and 18 respectively circumferential direction. Respective grooves 14, 16 and 18 extend parallelly to one another and are spaced apart from each other. Piston rings 20, 22 are received within the .
`~75312 groove 14 and piston ring 24 within groove 16. An oil-control ring 26 is received in the groove 18.
The piston 12 is pivotably secured on the top of a connecting rod 28 in a ~ se well known manner. The connecting rod 28 is attached at the lower end thereof to a crank pin of a crankshaft 30 to be driven by the engine revolution. The piston 12 is thus slidable along the axis of the engine cylinder 10. The lubricant oil is provided between the piston rings 20, 22 and 24 and the cylinder wall 32 of the engine cylinder 10 to allow smooth motion of the piston.
As shown in Fig. 2, the piston rings 20 and 22 have substantially the same configurations and have tapered faces 34 and 36 respectively opposing the cylinder wall 32.
The piston ring 20 directs its tapered face 34 upward and ; the piston ring 22 directs its tapered face 36 downward.
Both piston rings 20 and 22 are received within the groove 14 and have facing plane surfaces 38 and 40 respectively. Each of the piston rings 20 and 22 is .: .
,~ 20 movable with respect to the other according to the motion of the piston. Also, both piston rings 20 and 22 are movable back and forth with respect to the cylinder wall 32.
I ~The piston ring 24 and the oil-control ring 26 are received within the grooves 16 and 18 respectively in a per se welL-known manner and with functions the same as those of their conventional counterparts.
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` ~7~312 Fig. 2 shows the state where the piston 12 is travelling upward. During this upward compression stroke of the piston, the piston ring 20 faces its tapered face 34 against the lubricant oil layer established on the cylinder wall 32 to maintain a relatively thick lubricant oil layer between the piston ring 20 and the cylinder wall 32. On the other hand, since the piston ring 22 faces the horizontal plane 40 against the lubricant oil layer the lubricant oil layer is scraped off the cylinder wall to make the layer thinner than that established by the piston ring 20. Therefore, the scraped lubricant oil is forced into the space between the piston rings 20 and 22. The lubricant oil introduced into the groove 14 is stored in the space between the piston rings 20 and 22 and carried along with the piston rings 20 and 22. During high speed motion the relative position of piston rings 20 and 22 with respect to one another and with respect to the groove 14 is maintained as shown in Fig. 2. Adjacent the top dead center of the piston stroke, the relative speed of the piston rings 20 and 22 with respect to the cylinder wall 32 becomes approximately zero to stop scraping of the lubricant oil layer and to start and re-introducing the scraped lubricant oil. And by the high pressure of the gas in the combustion chamber the piston ring 20 is forced toward the piston ring 22 to reduce the space therebetween.
Due to the reduction of the space between the piston rings 20 and 22, the lubricant oil in the space is forced toward ' ~ 1753 ~ 2 the cylinder wall 32 to establish a lubricant oil layer on-the cylinder wall. By the establishment of the lubricant oil layer on the cylinder wall, the piston ring 22 is forced away from the cylinder wall 32. The lubricant oil layer established on the cylinder wall is thus pressurized according to ~he gas pressure applied to the piston rings 20 and 22 and has a sufficient thickness to prevent the piston rings and the cylinder wall from touching and cause friction losses during engine operation.
In the downward piston compression stroke, the lower piston ring 22 is subjected to the relatively thick lubricant oil layer to guide the lubricant oil into the space between the piston rings 20 and 22 and the lower piston ring 22 is pushed away from the cylinder wall 32, as shown in Fig. 3. The introduced lubricant oil is stored in the space between the upper and lower piston rings 20 and 22 and moves downward together with the piston 12 and piston rings 20 and 22.
Referring to Figs. 5 to 7, there is shown the second embodiment of the piston sealing structure according to the present invention. Similar to the foregoing first embodiment, the piston 50 is formed with circumferentially extending grooves 52, 54 and 56. The piston rings 58 and i 60 are received within the groove 52. The piston ring 62 `I 25 and the oil-control ring 64 are respectively received ¦ within the grooves 54 and 56 in per se well-known manner.
On the upper horizontal portion 66 of the groove ~7~3~ ~
52 is formed a circumferentially extending recess 68. A
cross-sectionally substantially hollow cicular ring 70 is received in the recess 68. The ring 70 contacts the piston ring 58 adjacent the inner end to elastically urge the inner end of the piston ring 58 toward the piston ring 60.
Similar to the foregoing first embodiment, the piston rings 58 and 60 have the same configuration and have tapered faces 72 and 74 respectively. The piston rings 58 and 60 are positioned to direct the tapered faces 72 and 74 up- and downwardly respectively. As shown in Figs. 5 to 7, the inner end of the piston ring 58 is urged by the ring 70 to contact with the inner end of the piston ring 600 In the compression stroke of the piston, the piston ring 58 maintains a relatively thick lubricant oil layer on the cylinder wall 76 and the piston ring 60 scrapes the lubricant oil to introduce the same into the space between the piston rings 58 and 60. According to the second embodiment, the piston rings 58 and 60 contact at their inner ends to prevent the lubricant oil from entering behind the inner end of the piston rings. Thus, even ¦ though the thickness of the lubricant oil layer is not remarkably varied, the sealing effect adjacent the top dead center of the piston stroke is sufficiently provided to effectively prevent blow by.
Figs. 8 to 10 show the third embodiment of the piston sealing structure according to the present invention. The piston 80 is formed with grooves 82, 84 and g L75~3 2 86. The groove 82 receives piston rings ~8 and 90 therein~
in a position directing the tapered faces 92 and 94 up- and downwardly, respectively. On the inner ends of the piston rings 88 and 9O, a sealing ring 96 is attached to close the inner end of the space 98 formed between the piston rings ~8 and 90. By closing the inner end of the space 98, the lubricant oil introduced into the space 98 is prevented from entering behind the inner end of the piston rings 88 and 90, similar to the foregoing second embodiment.
In Figs. 8 to 10, the reference numerals 100 and 102 represent the piston ring and the oil-control ring respectively received within the grooves 84 and 84 respectively in a per se well-known manner.
Figs. 11 to 14 respectively show the modifications of the third embodiment as set forth the above. In these modifications, variations of the piston rings are shown for the sealing structures of the piston.
In Fig. 11, there is shown the modification in which the piston rings 110 and 112 are received within the groove 113 to direct the tapered faces 114 and 116 upwardly~ The piston ring 110 has a tension larger than that of the piston ring 112.
In this construction, the lubricant oil is mainly scratched from the cylinder wall in the piston expansion stroke and brought into the space 11)3 between the piston rings 110 and 112. This may serve to reduce lubricant oil consumption. However, the tension of the piston rings 110 - -.
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and 112 can be alternated from the foregoing. Namely, if the larger tension is provided for the piston ring 112 with respect to the piston ring 110, the lubricant oil is introduced between the space of the piston rings in the piston compression stroke.
In Fig. 12, another modification o~ the third embodiment is illustrated. In this modification, the piston rings 120 and 122 are barrel ring having rounded outer contacting surfaces. The piston rings 120 and 122 are provide different tensions similar to the foregoing modification. The thickness of the lubricant layer is varied depending on the difference of the tension provided for the piston rings. Therefore, particularly in this modification, the tension of the piston ring 120 is preferable larger than that of the piston ring 122.
Fig. 13 shows a further modification of the third embodiment in which the piston rings 130 and 132 of different shapés are combined. In the specific construction, the barrel ring 130 and the tapered ring 132 are combined and received within the groove 134 of the piston. The tension of piston rings 130 and 132 can be set equal to one another or can be varied depending on the engine operating characteristics. Of course, it is possible to alternate the position of the piston rings 130 and 132u Also, the shapes of the piston rings to be provided in the piston groove can be varied or combined, in any way. For example, Fig. 14 shows one variation of the ~1~53~2 combination of the different-shaped piston rings 140 and 142. In this ma~ification, the piston ring 140 has a tapered face 144 ~irected upwardly and the piston ring 142 has plane contact ~ace 146 substantially parallel to the cylinder wall.
It shou~d be noted that since the piston ring located the other ~one is subject to substantially higher heat of the combustion gas, thus raising its temperature and reducing its tension, difference the tensions of the upper and lower pIston rings depends on engine operation.
Therefore, it i5 not essential to provide the difference of the tension for the piston rings.
According to the present invention, since there are provided two p~ston rings in the upper sealing groove, a better sealing e~ect can be expected. Since two piston ; rinys can provide a sufficient sealing effect, it is possible to remove the piston ring received in the lower sealing groove.
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Thus~ the present invention fulfills all of the objects and advantages sought thereto.
While the ;nvention has been illustrated in terms of the specific em~odiments of the invention for better understanding, it should be understood that the invention is not limited to the shown embodiments. It should be understood that any possible modifications upon the foregoing description and the principle of the invention are to be regarded as within the scope of the invention~
'' ' ~75312 For example, the shape or form of the piston rings can be modified in any way without departing from the principles as set forth hereabove.
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To accomplish the above-mentioned and other objects, there is provided an improved sealing structure ~ 17~312 for the piston for the internal combustion engine, in which two piston rings are disposed within a groove in a freely mov-~ble position with respect to one another and with respect to the groove. The piston rings scrape off the lubricant oil constructing the lubricant oil layer on the cylinder wall to introduce the same into a space therebetween during the expan-sion and compression piston strokes. Due to the substantially high gas pressure applied adjacent to the top dead center. The piston rings reduces the space therebetween to force the lubri-cant oil out from between the piston rings to the sliding clearance between the piston ring and the cylinder wall.
In accordance with one aspect of the present invention, there is provided an improved sealing structure for a piston of an internal combustion engine comprising: a piston formed with a plurality of grooves on the periphery thereof, and said piston including means for providing a lubricant oil to esta-blish a lubricant oil layer between said piston and cylinder wall of the engine cylinder; an oil-control ring, mounted in the groove in the lowermost position in said grooves; and a pair of piston rings disposed in the uppermost groove, being spaced apart from each other and movable independently of each other with respect to one another and with respect to said cylinder wall.
In another aspect, there is provided an improvement in a sealing structure for a piston of an internal combustion en-gine comprising: a piston disposed within an engine cylinder for reciprocation therewithin and being formed with first and second grooves on the peripherv thereof and e~tending circum-ferentially; an oil-control ring mounted on said second groove to control the amount of lubricant oil to be supplied between the piston and the cylinder wall of the engine cylinder; and a pair of piston rings disposed within the upyermost first groove and bein~ spaced from each other, each of said piston rings is so constructed as to be freely movable independently , -~, ~
~ 175312 of each other within said uppermost first groove in vertical direction, and each of said piston rings being variable of the diametPr thereof to var~ the clearance defined between said cylinder wall depending upon the pressure applied thereto.
In a further aspect of the invention, an improvement in a sealing structure for a piston of an internal combustion engine comprises: a piston disposed within an engine cylin-der for reciprocation therewithin and being formed with first and second grooves on the periphery thereof and extending circumferentially; an oil-control ring mounted on said second groove to control the amount of lubricant oil to be supplied between the piston and the cylinder all of the engine cylin-der; and a pair of piston rings disposed within the uppermost first groove and being spaced apart from each other, each of said piston being of size for free movement in said first groove in the vertical direction and defining therebetween a space to introduce lubricant oil during the piston stro~e, and the space between said piston rings being variable accord-ing to the relative position of the piston rings depending upon the lubricant oilpressure a~plied thereto so that thelubricant oil is introduced into sàid space as a pressure in a combustion chamber is relatively low and is pushed out as reducing said space by increasing of said pressure in the combustion chamber for establishmentof the lubricantoil layeron saidcylinder wall.
BRIEF DESCRIPTION OF THE DRAWINGS
. _ The present invention will be more fully understood from the detailed description given herebelow and from the ac-companyins drawings of the preferred embodiment of the present invention, which, however, should not be understood as limitive to the invention but are for elucidation and explanation only.
In the drawings:
~ 17~312 Fig. 1 is a longit~dinal section of an engine cylin-der including the first embodiment of a piston according to the present invention;
Fig. 2 is an enlarged section of the piston of ~ig. 1 showing the compression, stroke of the piston;
Fig. 3 is a similar view to Fig. 2 but showing the expansion stroke of the piston;
Fig. 4 is a further enlarged section showing the function of the sealing structure according to the first em-bodiment;
Fig. 5 is a section of the second embodiment of the piston according to the present invention, which illustrates the piston as in the compression stroke;
Fig. 6 is a similar view to Fig. 5 but showing the expansion stroke of the piston;
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~ 17~312 Fig. 7 is an enlarged section of the piston of Fig. 5 showing function of the sealing structure adjacent the top stop in the expansion stroke;
Fig. 8 is a section of the third embodiment of the piston according to the present invention, in which the piston is in the compression stroke;
Fig. 9 is a similar view to Fig. 8 but showing the expansion stroke of the piston;
~ ig. 10 is an enlarged section of the piston of Fig. 5 showing the function of the sealing structure adjacent the top dead center in the expansion stroke;
Figs. 11 to 14 are enlarged sections respectively showing variations of the sealing structure of the piston of Fig. 9.
It should be noted that the section of the piston ring, the space between the piston ring and the groove of the piston and so on are exaggerated for better understanding.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to the drawings, particularly to Fig. 1, there is illustrated an engine cylinder 10 in which a piston 12 is disposed in a slidable position. The piston 12 is constructed as a well known structure and has grooves 14, 16 and 18 respectively circumferential direction. Respective grooves 14, 16 and 18 extend parallelly to one another and are spaced apart from each other. Piston rings 20, 22 are received within the .
`~75312 groove 14 and piston ring 24 within groove 16. An oil-control ring 26 is received in the groove 18.
The piston 12 is pivotably secured on the top of a connecting rod 28 in a ~ se well known manner. The connecting rod 28 is attached at the lower end thereof to a crank pin of a crankshaft 30 to be driven by the engine revolution. The piston 12 is thus slidable along the axis of the engine cylinder 10. The lubricant oil is provided between the piston rings 20, 22 and 24 and the cylinder wall 32 of the engine cylinder 10 to allow smooth motion of the piston.
As shown in Fig. 2, the piston rings 20 and 22 have substantially the same configurations and have tapered faces 34 and 36 respectively opposing the cylinder wall 32.
The piston ring 20 directs its tapered face 34 upward and ; the piston ring 22 directs its tapered face 36 downward.
Both piston rings 20 and 22 are received within the groove 14 and have facing plane surfaces 38 and 40 respectively. Each of the piston rings 20 and 22 is .: .
,~ 20 movable with respect to the other according to the motion of the piston. Also, both piston rings 20 and 22 are movable back and forth with respect to the cylinder wall 32.
I ~The piston ring 24 and the oil-control ring 26 are received within the grooves 16 and 18 respectively in a per se welL-known manner and with functions the same as those of their conventional counterparts.
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` ~7~312 Fig. 2 shows the state where the piston 12 is travelling upward. During this upward compression stroke of the piston, the piston ring 20 faces its tapered face 34 against the lubricant oil layer established on the cylinder wall 32 to maintain a relatively thick lubricant oil layer between the piston ring 20 and the cylinder wall 32. On the other hand, since the piston ring 22 faces the horizontal plane 40 against the lubricant oil layer the lubricant oil layer is scraped off the cylinder wall to make the layer thinner than that established by the piston ring 20. Therefore, the scraped lubricant oil is forced into the space between the piston rings 20 and 22. The lubricant oil introduced into the groove 14 is stored in the space between the piston rings 20 and 22 and carried along with the piston rings 20 and 22. During high speed motion the relative position of piston rings 20 and 22 with respect to one another and with respect to the groove 14 is maintained as shown in Fig. 2. Adjacent the top dead center of the piston stroke, the relative speed of the piston rings 20 and 22 with respect to the cylinder wall 32 becomes approximately zero to stop scraping of the lubricant oil layer and to start and re-introducing the scraped lubricant oil. And by the high pressure of the gas in the combustion chamber the piston ring 20 is forced toward the piston ring 22 to reduce the space therebetween.
Due to the reduction of the space between the piston rings 20 and 22, the lubricant oil in the space is forced toward ' ~ 1753 ~ 2 the cylinder wall 32 to establish a lubricant oil layer on-the cylinder wall. By the establishment of the lubricant oil layer on the cylinder wall, the piston ring 22 is forced away from the cylinder wall 32. The lubricant oil layer established on the cylinder wall is thus pressurized according to ~he gas pressure applied to the piston rings 20 and 22 and has a sufficient thickness to prevent the piston rings and the cylinder wall from touching and cause friction losses during engine operation.
In the downward piston compression stroke, the lower piston ring 22 is subjected to the relatively thick lubricant oil layer to guide the lubricant oil into the space between the piston rings 20 and 22 and the lower piston ring 22 is pushed away from the cylinder wall 32, as shown in Fig. 3. The introduced lubricant oil is stored in the space between the upper and lower piston rings 20 and 22 and moves downward together with the piston 12 and piston rings 20 and 22.
Referring to Figs. 5 to 7, there is shown the second embodiment of the piston sealing structure according to the present invention. Similar to the foregoing first embodiment, the piston 50 is formed with circumferentially extending grooves 52, 54 and 56. The piston rings 58 and i 60 are received within the groove 52. The piston ring 62 `I 25 and the oil-control ring 64 are respectively received ¦ within the grooves 54 and 56 in per se well-known manner.
On the upper horizontal portion 66 of the groove ~7~3~ ~
52 is formed a circumferentially extending recess 68. A
cross-sectionally substantially hollow cicular ring 70 is received in the recess 68. The ring 70 contacts the piston ring 58 adjacent the inner end to elastically urge the inner end of the piston ring 58 toward the piston ring 60.
Similar to the foregoing first embodiment, the piston rings 58 and 60 have the same configuration and have tapered faces 72 and 74 respectively. The piston rings 58 and 60 are positioned to direct the tapered faces 72 and 74 up- and downwardly respectively. As shown in Figs. 5 to 7, the inner end of the piston ring 58 is urged by the ring 70 to contact with the inner end of the piston ring 600 In the compression stroke of the piston, the piston ring 58 maintains a relatively thick lubricant oil layer on the cylinder wall 76 and the piston ring 60 scrapes the lubricant oil to introduce the same into the space between the piston rings 58 and 60. According to the second embodiment, the piston rings 58 and 60 contact at their inner ends to prevent the lubricant oil from entering behind the inner end of the piston rings. Thus, even ¦ though the thickness of the lubricant oil layer is not remarkably varied, the sealing effect adjacent the top dead center of the piston stroke is sufficiently provided to effectively prevent blow by.
Figs. 8 to 10 show the third embodiment of the piston sealing structure according to the present invention. The piston 80 is formed with grooves 82, 84 and g L75~3 2 86. The groove 82 receives piston rings ~8 and 90 therein~
in a position directing the tapered faces 92 and 94 up- and downwardly, respectively. On the inner ends of the piston rings 88 and 9O, a sealing ring 96 is attached to close the inner end of the space 98 formed between the piston rings ~8 and 90. By closing the inner end of the space 98, the lubricant oil introduced into the space 98 is prevented from entering behind the inner end of the piston rings 88 and 90, similar to the foregoing second embodiment.
In Figs. 8 to 10, the reference numerals 100 and 102 represent the piston ring and the oil-control ring respectively received within the grooves 84 and 84 respectively in a per se well-known manner.
Figs. 11 to 14 respectively show the modifications of the third embodiment as set forth the above. In these modifications, variations of the piston rings are shown for the sealing structures of the piston.
In Fig. 11, there is shown the modification in which the piston rings 110 and 112 are received within the groove 113 to direct the tapered faces 114 and 116 upwardly~ The piston ring 110 has a tension larger than that of the piston ring 112.
In this construction, the lubricant oil is mainly scratched from the cylinder wall in the piston expansion stroke and brought into the space 11)3 between the piston rings 110 and 112. This may serve to reduce lubricant oil consumption. However, the tension of the piston rings 110 - -.
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and 112 can be alternated from the foregoing. Namely, if the larger tension is provided for the piston ring 112 with respect to the piston ring 110, the lubricant oil is introduced between the space of the piston rings in the piston compression stroke.
In Fig. 12, another modification o~ the third embodiment is illustrated. In this modification, the piston rings 120 and 122 are barrel ring having rounded outer contacting surfaces. The piston rings 120 and 122 are provide different tensions similar to the foregoing modification. The thickness of the lubricant layer is varied depending on the difference of the tension provided for the piston rings. Therefore, particularly in this modification, the tension of the piston ring 120 is preferable larger than that of the piston ring 122.
Fig. 13 shows a further modification of the third embodiment in which the piston rings 130 and 132 of different shapés are combined. In the specific construction, the barrel ring 130 and the tapered ring 132 are combined and received within the groove 134 of the piston. The tension of piston rings 130 and 132 can be set equal to one another or can be varied depending on the engine operating characteristics. Of course, it is possible to alternate the position of the piston rings 130 and 132u Also, the shapes of the piston rings to be provided in the piston groove can be varied or combined, in any way. For example, Fig. 14 shows one variation of the ~1~53~2 combination of the different-shaped piston rings 140 and 142. In this ma~ification, the piston ring 140 has a tapered face 144 ~irected upwardly and the piston ring 142 has plane contact ~ace 146 substantially parallel to the cylinder wall.
It shou~d be noted that since the piston ring located the other ~one is subject to substantially higher heat of the combustion gas, thus raising its temperature and reducing its tension, difference the tensions of the upper and lower pIston rings depends on engine operation.
Therefore, it i5 not essential to provide the difference of the tension for the piston rings.
According to the present invention, since there are provided two p~ston rings in the upper sealing groove, a better sealing e~ect can be expected. Since two piston ; rinys can provide a sufficient sealing effect, it is possible to remove the piston ring received in the lower sealing groove.
:
Thus~ the present invention fulfills all of the objects and advantages sought thereto.
While the ;nvention has been illustrated in terms of the specific em~odiments of the invention for better understanding, it should be understood that the invention is not limited to the shown embodiments. It should be understood that any possible modifications upon the foregoing description and the principle of the invention are to be regarded as within the scope of the invention~
'' ' ~75312 For example, the shape or form of the piston rings can be modified in any way without departing from the principles as set forth hereabove.
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Claims (35)
1. A sealing structure for a piston of an inter-nal combustion engine comprising: a piston formed with a plurality of grooves on the periphery thereof, and said piston including means for providing a lubricant oil to establish a lubricant oil layer between said piston and cylinder wall of the engine cylinder; an oil-control ring, mounted in the lowermost groove; and a pair of piston rings disposed in the uppermost groove, being spaced apart from each other and movable independently of each other to move with respect to one another and with respect to said cylinder wall.
2. A structure as set forth in claim 1, wherein said pair of piston rings are so arranged in said groove that the piston ring located trailing with respect to the motion direction of the piston serves to scrape the lubricant oil from the cylinder wall and introduce the scraped lubricant oil into the space defined between said piston rings.
3. A structure as set forth in claim 1, wherein the uppermost groove is dimenioned so as to permit free motion of the piston rings in axial and radial directions.
4. A structure as set forth in claim 1, which further comprises means for sealingly closing the inner end of the space defined between said piston rings.
5. A structure as set forth in claim 2 or 3, which further comprises means for sealingly closing the inner end of the space.
6. A structure as set forth in claim 3, wherein said pair of piston rings defines a space therebetween in such a manner that said space is variable according to relative motion of the piston rings and is filled with the lubricant oil.
7. A structure as set forth in claim 4, wherein said closing means is a sealing ring disposed within said uppermost groove in a position sealingly contacting to the inner ends of said piston rings.
8. A structure as set forth in claim 6, which further comprises means for sealingly closing the inner end of the space defined between said piston rings.
9. A structure as set forth in claim 8, wherein said closing means is an elastic member disposed within said uppermost groove to urge one of the piston rings towards the other piston ring to elastically contact the inner ends of said piston rings.
10. A structure as set forth in claim 7, wherein said piston rings have different tensions.
11. A structure as set forth in claim 7, wherein said piston rings define the space therebetween in such a manner that said space is variable according to relative motion thereof and said space is filled with the lubricant oil.
12. A structure as set forth in claim 10, wherein said piston rings have different tensions.
13. A structure as set forth in claim 10, wherein said piston rings have different configuration with respect to each other.
14. A sealing structure for a piston of an internal combustion engine comprising:
a piston disposed within an engine cylinder for reciprocation therewithin and being formed with first and second grooves on the periphery thereof and extending circumferentially;
an oil-control ring mounted on said second groove to control the amount of lubricant oil to be supplied between the piston and the cylinder wall of the engine cylinder; and a pair of piston rings disposed within the uppermost first groove and being spaced apart from each other, each of said piston rings is so constructed as to be freely movable independently of each other within said uppermost first groove in vertical direction, and each of said piston rings being variable of the diameter to vary the clearance between said cylinder wall depending on the pressure applied thereto.
a piston disposed within an engine cylinder for reciprocation therewithin and being formed with first and second grooves on the periphery thereof and extending circumferentially;
an oil-control ring mounted on said second groove to control the amount of lubricant oil to be supplied between the piston and the cylinder wall of the engine cylinder; and a pair of piston rings disposed within the uppermost first groove and being spaced apart from each other, each of said piston rings is so constructed as to be freely movable independently of each other within said uppermost first groove in vertical direction, and each of said piston rings being variable of the diameter to vary the clearance between said cylinder wall depending on the pressure applied thereto.
15. A sealing structure for a piston of an internal combustion engine comprising:
a piston disposed within an engine cylinder for reciprocation therewithin and being formed with first and second grooves on the periphery thereof and extending circumferentially;
an oil-control ring mounted on said second groove to control the amount of lubricant oil to be supplied between the piston and the cylinder wall of the engine cylinder; and a pair of piston rings disposed within the uppermost first groove and being spaced apart from each other, each of the piston rings being of size for free movement in said first groove in the vertical direction and defining therebetween a space to introduce the lubricant oil during the piston stroke, and the space between said piston rings being variable depending upon the lubricant oil pressure applied thereto so that the lubricant oil is introduced into said space as a pressure in the combustion chamber is relatively low and is pushed out as reducing said space by increasing of the pressure in the combustion chamber for establishment of the lubricant oil layer on said cylinder wall,
a piston disposed within an engine cylinder for reciprocation therewithin and being formed with first and second grooves on the periphery thereof and extending circumferentially;
an oil-control ring mounted on said second groove to control the amount of lubricant oil to be supplied between the piston and the cylinder wall of the engine cylinder; and a pair of piston rings disposed within the uppermost first groove and being spaced apart from each other, each of the piston rings being of size for free movement in said first groove in the vertical direction and defining therebetween a space to introduce the lubricant oil during the piston stroke, and the space between said piston rings being variable depending upon the lubricant oil pressure applied thereto so that the lubricant oil is introduced into said space as a pressure in the combustion chamber is relatively low and is pushed out as reducing said space by increasing of the pressure in the combustion chamber for establishment of the lubricant oil layer on said cylinder wall,
16. A structure as set forth in claim 14, which further comprises a closing means for sealingly closing the inner end of said space.
17. A structure as set forth in claim 15, which further comprises a closing means for sealingly closing the inner end of said space.
18. A structure as set forth in claim 16, wherein said closing means is a sealing ring disposed within said groove in a position sealingly contacting to the inner ends of said piston rings.
19. A structure as set forth in claim 17, wherein said closing means is a sealing ring disposed within said groove in a position sealingly contacting to the inner end of said piston rings.
20. A structure as set forth in claim 16 or 17, wherein said closing means is an elastic member disposed within said groove to urge one of said piston rings towards the other piston ring to elastically contact the inner ends of said piston rings.
21. A structure as set forth in claim 18 or 19, wherein said piston rings have different tension.
22. A structure as set forth in claim 18 or 19, wherein said piston rings have different configurations with respect to each other.
23. A piston assembly for an internal combustion engine comprising:
a piston head having ring grooves respectively extending circumferentially on the outer periphery thereof;
an oil-control ring disposed within one of said ring grooves;
a pair of piston rings disposed within another of said ring grooves and respectively being of size freely movable in said another groove in axial and radial directions, said piston rings being movable independently of each other and radially expandable of the diameter thereof;
first means for defining a clearance between said pair of pistons, which clearance is variable of axial dimension;
second means for introducing a lubricant oil into said clearance during piston compression stroke;
third hydraulic means, responsive to increasing of a pressure in and engine combustion chamber, for operating said second means so that said second means introduces the lubricant oil into said clearance; and four means, responsive to increasing of the pressure in said engine combustion chamber, for biasing said piston rings to move in a direction reducing said axial dimension of said clearance for pushing out the lubricant oil therein.
a piston head having ring grooves respectively extending circumferentially on the outer periphery thereof;
an oil-control ring disposed within one of said ring grooves;
a pair of piston rings disposed within another of said ring grooves and respectively being of size freely movable in said another groove in axial and radial directions, said piston rings being movable independently of each other and radially expandable of the diameter thereof;
first means for defining a clearance between said pair of pistons, which clearance is variable of axial dimension;
second means for introducing a lubricant oil into said clearance during piston compression stroke;
third hydraulic means, responsive to increasing of a pressure in and engine combustion chamber, for operating said second means so that said second means introduces the lubricant oil into said clearance; and four means, responsive to increasing of the pressure in said engine combustion chamber, for biasing said piston rings to move in a direction reducing said axial dimension of said clearance for pushing out the lubricant oil therein.
24. The piston assembly as set forth in claim 23, wherein said third hydraulic means is operable according to a hydraulic pressure within said another groove and operates said second means for scraping extra lubricant oil at an engine cylinder wall for introducing into said clearance.
25. The piston assembly as set forth in claim 23, wherein said second means radially moves said piston rings for variation of the diameters of said piston rings to adapt the piston rings for introducing the lubricant oil into said clearance.
26. The piston assembly as set forth in any one of claims 23 or 24, wherein said fourth means is active on said upper piston ring in response to the pressure in the combustion chamber higher than a given value to reduce said clearance to push out the lubricant oil to establish lubricant oil layer at the cylinder wall.
27. The piston assembly as set forth in claim 25, wherein said second means is active in response to the operation of said third hydraulic means for increasing diameters of said pistons, said second means varies the increasing rate of the piston ring diameters so that the lower piston ring expands the diameter at larger rate than that of the upper piston ring.
28. The piston assembly as set forth in claim 27, wherein said fourth means is active on said upper piston ring in response to the pressure in the combustion chamber higher than a given value to reduce said clearance to push out the lubricant oil to establish lubricant oil layer at the cylinder wall.
29. The piston assembly as set forth in claim 28, wherein said fourth means is active in a region where said piston is positioned adjacent a top dead center thereof.
30. The piston assembly as set forth in claim 28, which further includes a closure means for closing inner end of said clearance.
31. The piston assembly as set forth in claim 30, wherein said closure means comprises an annular ring which is variable the diameter corresponding to the pressure of the lubricant oil.
32. The piston assembly as set forth in claim 30, wherein each of said piston rings is provided different tension force in relation to each other.
33. The piston assembly as set forth in claim 30, wherein said closure means is a resilient member resiliently biasing the inner end of at least one of said piston rings toward the other piston ring.
34. The piston assembly as set forth in claim 32, wherein said piston rings are of the identical shape.
35. The piston assembly as set forth in claim 32, wherein said piston rings are of different shapes to each other.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000381026A CA1175312A (en) | 1981-07-02 | 1981-07-02 | Piston for an internal combustion engine |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000381026A CA1175312A (en) | 1981-07-02 | 1981-07-02 | Piston for an internal combustion engine |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1175312A true CA1175312A (en) | 1984-10-02 |
Family
ID=4120350
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000381026A Expired CA1175312A (en) | 1981-07-02 | 1981-07-02 | Piston for an internal combustion engine |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1175312A (en) |
-
1981
- 1981-07-02 CA CA000381026A patent/CA1175312A/en not_active Expired
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