JP2008095882A - Piston oil ring structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piston oil ring structure effectively utilizing an existing side rail for improving oil scraping performance and reducing oil consumption while suppressing a cost increase with a change of a material into new one. <P>SOLUTION: An oil ring consists of an upper side rail and a lower side rail 232 provided on the upper and lower sides of a piston in the axial direction, and a coil expander combined with the side rails and provided therebetween. At predetermined positions of certain circumferential intervals on the lower side rail 232, a plurality of low rigidity portions 232b are provided for partially lowering the rigidity of the side rail 232. Each low rigidity portion 232b is constituted of a through-hole passing through the lower side rail 232 in the axial direction of the piston. The through-hole is an oblong hole long in the circumferential direction of the lower side rail 232. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an oil ring structure of a piston, and in particular, relates to a measure for achieving follow-up performance against deformation of a cylinder bore by effectively utilizing an existing oil ring.

  Generally, as an oil ring of a piston of an internal combustion engine, a pair of upper and lower side rails in the axial direction of the piston are combined between the pair of side rails and the pair of side rails. A three-piece type including an expander that applies tension to each side rail is used (see, for example, Patent Document 1). Such an oil ring has a function of evenly applying the lubricant to the cylinder bore and a function of recovering excess lubricant. If there is no lubricant, the pressure ring and the piston are seized against the cylinder bore immediately. Will be caused.

In this case, if the amount of lubricating oil applied to the cylinder bore is large or is not recovered, the lubricating oil will be carried to the combustion chamber and burned, resulting in an increase in the amount of lubricating oil consumed. Therefore, in order to reduce the consumption of lubricating oil, it is important to keep the amount of lubricating oil applied to the cylinder bore thin as long as the cylinder, piston and pressure ring do not seize, and to recover excess lubricating oil efficiently. Therefore, it is necessary to increase the ring tension that is the basis of the force with which the side rail presses the cylinder bore as compared with the pressure ring.
JP-A-6-249341

  By the way, the cylinder bore receives the fastening force of the bolt when the bolt is fastened to the cylinder block of the cylinder head, and the upper part of the cylinder bore in the vicinity of the bolt expands outward in the radial direction. If the cylinder bores are subject to secondary deformation (shape having two protruding parts on the circumference) due to thermal deformation, and these overlap, then the sixth deformation (2nd, 4th, and 6th orders are representative and have large influences). For this reason, the outer periphery of the oil ring cannot contact the cylinder bore over the entire periphery, and excess lubricant that adheres to the cylinder bore can be efficiently recovered by a gap formed between a part of the outer periphery of the oil ring and the cylinder bore. As a result, the scraping performance of the lubricating oil deteriorates and the consumption of the lubricating oil increases.

  In this case, the side rail is made of a material that is easily elastically deformed instead of the existing material, thereby improving the followability of the side rail against the deformation of the cylinder bore and efficiently recovering excess lubricating oil adhering to the cylinder bore. It is conceivable to improve the scraping performance of the lubricating oil and reduce the consumption of the lubricating oil.

  However, in the above-mentioned proposal, since the material of the side rail itself must be changed and dealt with, there is a risk that the cost of the oil ring may increase, and an inexpensive oil ring can be used by effectively utilizing the existing side rail. There is a request to provide.

  The present invention has been made in view of the above points, and the object of the present invention is to effectively follow the deformation of the cylinder bore while suppressing the cost increase associated with a new material change by effectively using the existing side rail. To provide an oil ring structure of a piston that can improve and efficiently recover excess lubricating oil adhering to the cylinder bore, improve the scraping performance of the lubricating oil, and reduce the consumption of the lubricating oil is there.

  In order to achieve the above object, in the present invention, a pair of upper and lower side rails in the piston axial direction are combined between a pair of substantially annular side rails, and the pair of side rails. A piston oil ring structure including an expander that applies tension to the side rail is assumed. A plurality of low-rigidity portions that partially reduce the rigidity of the siderails are provided at predetermined positions in the circumferential direction of the siderails.

  Because of this specific matter, the side rail itself is partially lowered at the predetermined position in the circumferential direction due to the plurality of low rigidity portions provided at the predetermined position in the circumferential direction. Although it is a side rail made of a material, the structure is easily elastically deformed. For this reason, the side rail effectively follows the deformation of the cylinder bore caused by the bolt fastening force between the cylinder head and the cylinder block, and the deformation of the cylinder bore caused by the thermal deformation, so that the gap between the outer periphery of the oil ring and the cylinder bore There is no gap in the oil ring, and the outer periphery of the oil ring contacts the cylinder bore over the entire periphery. As a result, the followability of the side rail with respect to the deformation of the cylinder bore is improved, and excess lubricant adhering to the cylinder bore can be efficiently recovered, and the scraping performance of the lubricant can be improved. It is also possible to reduce consumption.

  In addition, the side rail is configured by providing a plurality of low-rigidity portions at predetermined positions at predetermined intervals in the circumferential direction, so that the existing side rail can be used effectively and the cost is increased due to new material changes. This makes it possible to provide an inexpensive oil ring.

  Further, when the plurality of low-rigidity parts are formed by through holes that penetrate the side rail in the piston axial direction, the low-rigidity parts are formed simply by penetrating the through-holes in the piston axial direction. Can be further reduced.

  And, when the through hole is formed in an oblong hole shape or a circular hole shape that is long in the circumferential direction of the side rail, it becomes a shape in which local stress concentration around the through hole is easily avoided, The durability of the side rail can be improved.

  Further, a predetermined circumferential direction of the side rail corresponding to a convex deformation portion protruding inward and outward in the radial direction when the cylinder bore is deformed by a bolt fastening force to the cylinder block of the cylinder head and when the cylinder bore is deformed due to thermal deformation. When the plurality of low rigidity portions are provided at the position, the side rail effectively follows the deformation of the cylinder bore caused by the bolt fastening force or the deformation of the cylinder bore caused by the thermal deformation, and the outer periphery of the oil ring and the cylinder bore The outer circumference of the oil ring makes smooth contact with the cylinder bore over the entire circumference, recovering the excess lubricating oil adhering to the cylinder bore more efficiently, and improving the scraping performance of the lubricating oil. In addition to being able to improve further, the consumption of lubricating oil can be further reduced. It is possible.

  Further, when the plurality of low-rigidity portions are provided only on the side rail on the lower side in the piston axial direction, the lubricating oil is closed between the side rail on the upper side in the piston axial direction and the upper side surface of the oil ring groove of the piston. As a result, the scraping performance of the lubricating oil can be further improved, and the consumption amount of the lubricating oil can be further reduced.

  In short, by providing a plurality of low-rigidity parts that partially reduce the rigidity at predetermined positions in the circumferential direction of the siderail, it becomes a structure that is easily elastically deformed despite being a siderail made of existing materials. Enhances the side rail followability to cylinder bore deformation, efficiently recovers excess lubricant adhering to the cylinder bore, improves the scraping performance of the lubricant, and reduces the amount of lubricant consumed It can also be made. In addition, it is possible to provide an inexpensive oil ring by effectively using existing side rails and suppressing an increase in cost.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a cross-sectional view of the vicinity of a piston having an oil ring structure according to a first embodiment of the present invention. A top ring groove 11, a second ring groove 12, and a third ring groove 13 are formed on an upper outer peripheral surface of the piston 1. The compression rings 21 and 22 and the oil ring 23 are mounted in the ring grooves 11 to 13 respectively.

  Here, the compression rings 21 and 22 block the gap between the piston 1 and the cylinder bore 31 of the cylinder 3, and suppress the leakage of compressed gas and high-pressure fuel gas from the combustion chamber 10 to the crankcase (not shown) as blow-by gas. The heat received by the piston 1 is transmitted to the cylinder bore 31 to perform a heat dissipation function.

  On the other hand, the oil ring 23 includes a pair of upper and lower side rails 231 and 232 provided vertically in the piston 1 axial direction, and a coil expander 233 combined between the upper and lower side rails 231 and 232 ( A so-called three-piece type equipped with an expander). Each side rail 231, 232 has an abutment 232 a (only the abutment of the lower side rail 232 is shown in FIG. 2) and is formed in a substantially annular shape, and is made of a conventionally known thin metal. The coil expander 233 is formed in a substantially annular shape so as to press the side rails 231 and 232 combined with the coil expander 233 from the inner peripheral side to apply tension to the side rails 231 and 232. And has a plurality of through holes penetrating from the inner circumference side to the outer circumference side at predetermined intervals in the circumferential direction. The oil ring 23 is responsible for controlling the formation of the lubricating oil film in the cylinder bore 31. That is, the oil ring 23 is combined with the upper and lower side rails 231 and 232 and the coil expander 233 so that the oil (lubricating oil) can be easily scraped off. The oil scraped off from 31 is guided from each through hole of the coil expander 233 to the inner peripheral surface of the ring groove (third ring groove) 13, and an oil drain hole formed in the inner peripheral surface of the third ring groove 13. It is dropped into the inside of the piston 1 via 234 and collected.

  As a characteristic part of the present invention, as shown in FIG. 2, the lower side rail 232 has a plurality of low positions that partially reduce the rigidity of the side rail 232 at predetermined positions at predetermined intervals in the circumferential direction. Rigid portions 232b, 232b,... Are provided. Each of the low-rigidity portions 232b includes a through hole that penetrates the lower side rail 232 in the direction of the axis of the piston 1, and the through hole is formed in an oblong hole shape that is long in the circumferential direction of the lower side rail 232. Yes. In this case, each low-rigidity part 232b is provided only on the lower side rail 232, and the upper-side side rail 231 has no low-rigidity part.

  Therefore, in the first embodiment, the lower side rail 232 has a circular rigidity of the lower side rail 232 itself by the plurality of low rigidity portions 232b, 232b,... Provided at predetermined positions at predetermined intervals in the circumferential direction. Since it is partially lowered at predetermined positions at predetermined intervals in the circumferential direction, it has a structure that is easily elastically deformed despite the lower side rail 232 made of an existing material. For this reason, the lower side rail 232 effectively follows the deformation of the cylinder bore 31 caused by the bolt fastening force between the cylinder head and the cylinder block 3 and the deformation of the cylinder bore 31 caused by thermal deformation. No gap is created between the outer periphery of the oil ring 23 and the cylinder bore 31, and the outer periphery of the oil ring 23 smoothly contacts the cylinder bore 31 over the entire periphery. As a result, the followability of the lower side rail 232 to the deformation of the cylinder bore 31 is improved, the excess oil adhering to the cylinder bore 31 can be efficiently recovered, and the oil scraping performance can be improved. Consumption can also be reduced.

  Moreover, the lower side rail 232 is configured by providing a plurality of low-rigidity portions 232b, 232b,... At predetermined positions at predetermined intervals in the circumferential direction, so that the existing lower side rail 232 is effective. It is possible to provide an inexpensive oil ring 23 while suppressing an increase in cost associated with a new material change.

  Further, since the plurality of low-rigidity portions 232b, 232b,... Are formed by through holes that penetrate the lower side rail 232 in the piston 1 axial direction, the low rigidity portions 232b, 232b,. The rigid portion 232b is formed, and the cost can be further reduced. In addition, since the through hole is formed in the shape of an oblong hole that is long in the circumferential direction of the lower side rail 232, it is easy to avoid local stress concentration with respect to the periphery of the through hole. The durability of 232 can be improved.

  Furthermore, since the plurality of low-rigidity portions 232b, 232b,... Are provided only on the lower side rail 232, the oil is closed between the upper side rail 231 and the upper side surface of the third ring groove 13. Therefore, it is very advantageous for improving the oil scraping performance and reducing the oil consumption.

  Next, a second embodiment of the present invention will be described with reference to FIG.

  In this embodiment, the configuration of the lower side rail is changed. In addition, the structure other than a lower side rail is the same as that of the case of the said Example 1, The same code | symbol is attached | subjected about the same part and the detailed description is abbreviate | omitted.

  That is, in the present embodiment, as shown in FIG. 3, the lower side rails 235 are circularly arranged at predetermined positions at predetermined intervals in the circumferential direction so that the rigidity of the lower side rails 235 is partially reduced. A plurality of low-rigidity portions 235b, 235b,... Formed in a hole shape are provided. Each of the low-rigidity portions 235b includes a through hole that penetrates the lower side rail 235 in the direction of the axis of the piston. The lower side rail 235 has an abutment 235a, is formed in a substantially annular shape, and is made of a conventionally known thin metal.

  In this case, since each low-rigidity portion 235b has a circular hole shape, a large number of low-rigidity portions 235b are provided in a dense arrangement in the circumferential direction, and are more easily elastically deformed than those having a long circular hole shape in the circumferential direction. It has become. Each low-rigidity portion 235b is provided only on the lower side rail 235.

  Therefore, in the second embodiment, the lower side rail 235 is formed by the plurality of low-rigidity portions 235b, 235b,... Having a circular hole provided at predetermined positions at predetermined intervals in the circumferential direction. Is partially reduced at predetermined positions at predetermined intervals in the circumferential direction, so that the structure is easily elastically deformed despite the lower side rail 235 made of an existing material. For this reason, the lower side rail 235 effectively follows the deformation of the cylinder bore 31 caused by the bolt fastening force between the cylinder head and the cylinder block 3 and the deformation of the cylinder bore 31 caused by thermal deformation, and the oil ring 23. No gap is generated between the outer periphery of the oil ring 23 and the cylinder bore 31, and the outer periphery of the oil ring 23 is smoothly contacted by the cylinder bore 31 over the entire periphery. As a result, the followability of the lower side rail 235 to the deformation of the cylinder bore 31 is further improved, and excess oil adhering to the cylinder bore 31 can be recovered more efficiently, and the oil scraping performance can be further improved. In addition, the oil consumption can be further reduced.

  Moreover, the lower side rail 235 is configured by providing a plurality of low-rigidity portions 235b, 235b,... At predetermined positions at predetermined intervals in the circumferential direction, so that the existing lower side rail 235 is effective. It is possible to provide an inexpensive oil ring 23 while suppressing an increase in cost associated with a new material change.

  Further, since the plurality of low-rigidity portions 235b, 235b,... Are formed by circular hole-shaped through holes that penetrate the lower side rail 235 in the piston 1 axial direction, The low-rigidity portion 235b is formed only by penetrating the through-hole, and the cost can be further reduced in combination with the ease of processing. Moreover, since the through hole is formed in a circular hole shape, local stress concentration with respect to the periphery of the through hole is more easily avoided, and the durability of the lower side rail 235 can be further improved. it can.

In addition, this invention is not limited to said each Example, The other various modifications are included. For example, in each of the above-described embodiments, the plurality of low-rigidity portions 232b and 235b are provided at predetermined positions at predetermined intervals in the circumferential direction of the lower side rails 232 and 235. However, this is caused by the bolt fastening force of the cylinder head to the cylinder block. Even if a plurality of low-rigidity portions are provided at positions corresponding to the circumferential direction of the lower side rail corresponding to the convex deformation portion that protrudes radially inward and outward when the cylinder bore is deformed and when the cylinder bore is deformed due to thermal deformation Well, in that case, the side rail effectively follows the deformation of the cylinder bore caused by the bolt fastening force and the deformation of the cylinder bore caused by the thermal deformation, and a gap is generated between the outer periphery of the oil ring and the cylinder bore. No, the outer circumference of the oil ring smoothly contacts the cylinder bore over the entire circumference and attached to the cylinder bore. Further efficiently recover excess oil that, on it is possible to further improve the scraping performance of the oil, it is possible to further reduce the consumption of oil.
In each of the above embodiments, the plurality of low-rigidity portions 232b and 235b are formed by an oblong hole shape or a circular hole shape through hole that penetrates the lower side rails 232 and 235 in the axial direction of the piston. Each low-rigidity part may be formed by a rectangular hole shape or a polygonal hole shape through hole that penetrates the lower side rail in the piston axial direction.

  Furthermore, in each said embodiment, although each low-rigidity part 232b, 235b was provided only in the lower side rail 232,235, each low-rigidity part may be provided also in the upper side rail.

It is sectional drawing of the oil ring vicinity of the piston which concerns on Example 1 of this invention. It is a top view of the lower side rail of an oil ring similarly. It is a top view of the lower side rail of the oil ring which concerns on Example 2 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Piston 23 Oil ring 231 Upper side rail 232 Lower side rail 232b Low rigidity part 233 Coil expander (expander)
235 Lower side rail 235b Low rigidity part 3 Cylinder block 31 Cylinder bore

Claims (5)

A pair of upper and lower side rails in the piston axial direction, and an expander that is combined between the pair of side rails and presses the side rails from the inner peripheral side to apply tension to the side rails. An oil ring structure of a piston provided,
A piston oil ring structure characterized in that a plurality of low-rigidity portions for partially lowering the rigidity of the siderails are provided at predetermined positions in the circumferential direction of the siderails. The oil ring structure of the piston according to claim 1,
The plurality of low-rigidity portions are formed by through holes that penetrate the side rails in the piston axial direction. The oil ring structure of the piston according to claim 2,
The oil ring structure of a piston, wherein the through hole is formed in an oblong hole shape or a circular hole shape that is long in a circumferential direction of the side rail. In the oil ring structure of the piston according to any one of claims 1 to 3,
The plurality of low-rigidity portions correspond to convex deformation portions that protrude radially inward and outward when the cylinder bore is deformed by a bolt fastening force to the cylinder block of the cylinder head and when the cylinder bore is deformed by thermal deformation. The piston oil ring structure is provided at predetermined positions in the circumferential direction. In the oil ring structure of the piston according to any one of claims 1 to 4,
The piston oil ring structure, wherein the plurality of low-rigidity portions are provided only on a side rail on a lower side in the piston axial direction.

Images