JP2007064346A - Pressure ring and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pressure ring capable of exhibiting suppression effects of increase in contact pressure in an abutment part, securing ring-assembling performance without being dropped out from a ring groove, easily processed, preventing fluttering and having excellent sealing performance, and a method for manufacturing the pressure ring. <P>SOLUTION: Thickness of an opposite abutment part in the diametrical direction of the pressure ring 1 passing through the abutment part end face in the state where the abutment part 5 is closed is 2.5 to 5.0% of the diameter of the pressure ring 1. In the state where the abutment part 5 is closed, the outer periphery 2 and inner periphery 3 of the pressure ring 1 are circular. The center 8 of the outer periphery 3 is shifted from the center 9 of the inner periphery 2 to the opposite abutment part side, in the diametrical direction of the pressure ring 1 passing through the abutment part end face. The abutment part side is set thinnest, and the opposite abutment part side is set thickest. Thickness of the abutment part in the diametrical direction is 50 to 70% of that of the opposite abutment part in the diametrical direction. The pressure ring 1 can be manufactured only by cutting or grinding an outer peripheral face of a ring material body having constant thickness in the diametrical direction. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a pressure ring and a method for manufacturing the same, and more particularly to a pressure piston ring for an internal combustion engine such as a diesel engine, a gasoline engine, and a gas engine, and a method for manufacturing the same.

  Conventional pressure rings generally have the same radial thickness over the entire circumference. Here, it is known that in a high-power diesel engine or the like that has a particularly high thermal load during actual operation, the joint portion is stretched due to thermal expansion, and the surface pressure in the vicinity of the joint portion increases. For this reason, partial wear, scuffing, cracks, and peeling of the surface treatment film are likely to occur. Therefore, in order to obtain a low-point piston ring whose surface pressure in the vicinity of the abutment part is severe compared to other parts, the predetermined surface with the end face of the abutment part on the inner peripheral surface side of the pressure ring. A notch that forms a part of the inner peripheral surface is formed over the circumferential length portion, and the radial thickness of the predetermined circumferential length portion is compared with the radial thickness of the portion other than the predetermined circumferential length portion. Thin piston rings have been proposed. However, it is generally difficult to process the inner periphery of the piston ring, and there is a problem that it becomes difficult to process particularly as the ring becomes smaller.

In Patent Document 1, in order to increase the strength and durability of the pressure ring without increasing the weight of the piston ring, the radial thickness of the piston ring is thinner in the vicinity of the abutment portion and gradually increases as the distance from the abutment portion increases. A pressure ring is proposed in which the portion on the opposite side of the ring diameter direction with respect to the abutment portion is maximized. Compared with a conventional ring having a constant radial thickness, such a ring has a smaller thickness at the abutment portion in the piston ring radial direction, and the thickness of the portion opposite to the diameter direction of the abutment portion (the anti-abutment portion) is It is thicker.
JP-A-9-196171

  However, since the pressure ring of Patent Document 1 has the same weight as a conventional ring having a constant radial thickness, the weight is still heavy, and the ring is lifted in the piston groove by the inertial force received from the piston vertical movement. The fluttering phenomenon is likely to occur, and therefore the sealing performance is deteriorated, and there are problems of oil consumption and an increase in blow-by gas.

  Furthermore, since the thickness of the ring on the side of the counter opening is thicker than the thickness of a conventional ring having a constant thickness in the radial direction, the depth of the ring groove in which the ring is mounted is increased accordingly. Normally, a plurality of pressure rings are mounted on the piston side by side in the piston axial direction. When the ring groove becomes deeper, the protruding length in the piston radial direction of the piston land portion between the first ring groove and the second ring groove increases. Therefore, there is a risk of breakage in the vicinity of the base portion, and if broken, the pressure ring may be broken. In addition, since the thickness in the ring radial direction is not uniform, the processing method is expected to be difficult, but no specific processing method is proposed.

  Therefore, the present invention can exhibit the effect of suppressing the increase in surface pressure at the abutment portion, and can be easily assembled and processed without fluttering, since there is no breakage near the base portion of the piston land portion or breakage of the pressure ring. An object of the present invention is to provide a pressure ring with good sealing performance and a method for manufacturing the same.

  In order to achieve the above object, the present invention has an abutment portion, and in the diametrical direction of the ring passing through the abutment portion end surface, the diametric thickness of the ring is the diametrically opposite portion from the abutment portion. In the pressure ring that gradually increases toward the counter-abutting part and has the maximum thickness at the counter-abutting part, the counter-current in the diametrical direction of the pressure ring that passes through the end face of the abutment part in a state where the abutment part is closed. The thickness of the joint portion is 2.5 to 5.0% of the outer diameter of the pressure ring, and the outer periphery and the inner periphery of the pressure ring are both round when the joint portion is closed. The center of the outer periphery is shifted to the side of the counter-abutting part from the center of the inner periphery in the diameter direction of the pressure ring that passes through the end surface of the joint part, and the thickness in the diameter direction of the joint part is the diameter of the counter-joint part A pressure ring is provided that is 50-70% of the directional thickness.

  The present invention further includes a step of manufacturing a pressure ring material having an outer periphery and an inner periphery such that the thickness in the diametrical direction is substantially constant and having a joint portion, and the joint portion of the pressure ring material is closed. In addition, the center of rotation is displaced by a predetermined amount in the diameter direction of the pressure ring material passing through the end face of the joint portion from the center position of the closed pressure ring material in the direction opposite to the joint portion in the diameter direction of the pressure ring material. Holding the pressure ring material in a cutting machine or a grinding machine in a state where the pressure ring material is held, and rotating the pressure ring material held by the cutting machine or the grinding machine around a rotation center where the pressure ring material is displaced. The predetermined amount corresponds to 1/2 of the cutting allowance or grinding allowance on the side of the joint portion, the cutting amount or grinding amount at the joint portion is the maximum, and the anti-joint portion The pressure at which the cutting amount or grinding amount is substantially zero It provides a method of manufacturing a ring.

  According to the pressure ring of claim 1, since not only the outer periphery of the ring but also the inner periphery of the ring is a perfect circle, the entire inner periphery of the ring can be in good contact with the ring groove to improve the sealing performance. Ring processing by grinding or the like is also easy.

  Further, since the thickness in the diameter direction of the pressure ring gradually increases from the abutment portion toward the counter-abutment portion, and the thickness in the diameter direction of the abutment portion is 70% or less of the thickness in the diameter direction of the anti-abutment portion, The effect of suppressing an increase in surface pressure at the abutment when a thermal load acts can be exhibited. Furthermore, since the thickness in the diameter direction of the joint portion is 50% or more of the thickness in the diameter direction of the anti-joint portion, the portion near the joint portion does not fall out of the ring groove, and the assembling property of the ring can be secured.

  Moreover, since the thickness of the counter opening is 2.5 to 5.0% of the outer diameter of the pressure ring, the thickness of the opposite side portion is equivalent to the thickness of the conventional pressure ring having a constant thickness. . Therefore, compared with a ring having a constant thickness over the entire circumference of the ring and a ring of Patent Document 1 in which the joint portion side is thin and the counter-joint portion side is thickened to have the same weight as the constant thickness ring, the joint portion Since the weight of the part is reduced, the inertia force can be reduced, fluttering due to the inertia force can be suppressed, sealing performance can be improved, oil consumption can be reduced, and blow-by gas can be reduced. In addition, since it is not necessary to make the thickness of the counter opening portion thicker than the conventional ring having a constant thickness, it is not necessary to form a deep ring groove, and a plurality of piston rings are mounted on the piston side by side in the piston axial direction. In this case, it is not necessary to increase the protruding length in the piston radial direction of the piston land portion between the first ring groove and the second ring groove, and breakage of the piston land portion can be prevented.

  According to the method for manufacturing a pressure ring according to claim 2, since a conventional pressure ring having an outer periphery and an inner periphery in which the thickness in the diameter direction is substantially constant and having an abutment portion is used as a pressure ring material, There is no special requirement for the dimensions of the material, and it can be manufactured at low cost.

  Further, since the center of rotation is eccentrically set in a predetermined direction in a predetermined direction on a cutting machine or a grinding machine, and then only the outer periphery is processed, the processing of the outer peripheral surface is extremely easy. Note that the amount of cutting or grinding at the counter-abutting portion is substantially zero includes the case where the counter-aperture portion is slightly inevitably cut or ground by a cutting machine or a grinding machine.

  A pressure ring according to an embodiment of the present invention will be described with reference to FIG. The pressure ring 1 is a ring made of iron, preferably steel, and has a shape defined by an inner periphery 2 and an outer periphery 3, and includes a joint portion 5. In the diameter direction of the pressure ring 1 passing through the end face of the joint portion 5 in a state where the joint portion 5 is closed, the thickness of the portion opposite to the joint portion (referred to as the anti-joint portion 6) is 2 of the outer diameter of the pressure ring 1. .5 to 5.0%. This ratio is equal to the ratio of the outer diameter to the thickness in a conventional pressure ring with a constant radial thickness. For example, in the case of a pressure ring for an automobile having an outer diameter of 60 mm to 150 mm, the thickness of the counter opening is in the range of 2.5 mm to 6.0 mm.

  Further, in the diameter direction 7 of the ring passing through the end face of the joint portion, the thickness in the diameter direction of the ring gradually increases from the joint portion 5 toward the reaction joint portion 6 on the diametrically opposite portion of the joint portion. At the maximum thickness. In other words, the thickness in the vicinity of the abutment portion 5 is smaller than the thickness of the conventional pressure ring having a constant radial thickness. Furthermore, since the counter-aperture part side is the same as the thickness of a conventional ring having a constant radial thickness, the mass of the entire ring is smaller than that of a conventional ring having a constant radial thickness. Therefore, compared with a ring having a constant thickness over the entire circumference of the ring and a ring of Patent Document 1 in which the joint portion side is thin and the counter-joint portion side is thickened to have the same weight as the constant thickness ring, the joint portion Since the weight of the part is reduced, the inertia force can be reduced, fluttering due to the inertia force can be suppressed, sealing performance can be improved, oil consumption can be reduced, and blow-by gas can be reduced. Further, since it is not necessary to make the thickness of the counter-joining portion 6 thicker than that of a conventional ring having a constant thickness, there is no need to form a deep ring groove, and a plurality of piston rings are mounted on the piston side by side in the piston axial direction. In this case, it is not necessary to increase the protruding length in the piston radial direction of the piston land portion between the first ring groove and the second ring groove, and the piston land portion can be prevented from being broken. In addition, since the thickness of the ring in the radial direction gradually decreases from the counter-abutting portion 6 toward the abutting portion 5, it is the maximum that leads to ring breakage with the same tension as a conventional ring having a constant thickness. It is possible to reduce the weight while maintaining the same operating stress.

  And the thickness of the diameter direction of the abutment part 5 is 50 to 70% of the thickness of the diameter direction of the anti-abutment part 6. If it is less than 50%, the thickness is too small, and the assembling property, which is the performance that the part on the side of the abutment part 5 is held in the ring groove, may be lowered, and the part on the side of the abutment part may fall off the ring groove. is there. On the other hand, if it exceeds 70%, the effect of suppressing the increase in the surface pressure at the joint portion cannot be exhibited.

  Further, the outer periphery 3 and the inner periphery 2 of the pressure ring 1 are both perfect circles in a state in which the joint portion 5 is closed, and the center 8 of the outer periphery 3 is the center of the inner periphery 2 in the diameter direction 7 of the pressure ring passing through the end surface of the joint portion. It is shifted by X / 2 from 9 to the counter opening 6 side. Here, X is the difference between the outer diameter d2 of the conventional ring having a constant thickness at the center 9 and the outer diameter d1 of the ring 1 of the present embodiment at the center 8 and is a cutting allowance for a joint portion described later. The center 9 of the inner periphery 2 is also the center of the outer periphery of a conventional ring having a constant radial thickness (the wavy line in FIG. 1).

  Since not only the ring outer periphery 3 but also the ring inner periphery 2 is a perfect circle, the entire inner periphery can be in good contact with the ring groove to improve the sealing performance, and the ring can be easily processed by cutting or grinding. The degree of freedom of the construction method is increased and processing at low cost is possible. In addition, a perfect circle means the circle | round | yen provided with the roundness of the grade obtained when a workpiece is rotated centering | focusing on a predetermined | prescribed rotation axis | shaft here and it cuts or grinds.

  The conventional ring 20 having a constant radial thickness, the pressure ring 30 of Patent Document 1, and the pressure ring 1 according to the present embodiment were compared with the cross-sectional view of FIG. As apparent from FIG. 2, the pressure ring 1 according to the present embodiment is the same as the thickness of the conventional ring 20 having a constant radial thickness on the side of the counter-joining portion 6, but the thickness of the joint portion 5 is The thickness in the conventional pressure ring 20 having a constant radial direction is thinner. On the other hand, the pressure ring 30 of Patent Document 1 is thicker on the side opposite to the joint portion than the thickness of the ring 20 having a constant radial thickness, and the wall thickness of the joint portion 5 is constant in the conventional radial direction. Less than the thickness of the pressure ring 20. Therefore, it is clear that the pressure ring 1 according to the present embodiment has a smaller mass than the conventional pressure rings 20 and 30.

Next, the manufacturing method of the pressure ring 1 by this Embodiment is demonstrated. First, a steel pressure ring material having an outer periphery 4 and an inner periphery 2 in which the thickness in the diametrical direction (a1 dimension) is substantially constant and having a joint portion is manufactured. This pressure ring material has an outer diameter of d2 and a center of 9 with the joint portion closed.
Next, the joint portion of the pressure ring material is brought into a closed state, and the center of rotation 9 in the diameter direction 7 of the pressure ring material passing through the end face of the joint portion rather than the center position 9 of the closed pressure ring material. The pressure ring material is held in a cutting machine (not shown) in a state where is displaced by a predetermined amount X / 2. Here, X is a cutting allowance for the outer periphery on the side of the joint portion 5.

  Next, the outer peripheral surface is cut by rotating the pressure ring material held by the cutting machine around the displaced rotation center 8. Accordingly, the radial thickness of the joint portion is a1-X, the radial thickness of the counter-joint portion is still a1, and as a result, the outer diameter when the pressure ring 1 is closed is d1 (d2> d1). ). In this way, since the center of rotation is eccentrically set in a predetermined direction in a predetermined direction on the cutting machine and then only the outer periphery is processed, the processing of the peripheral surface is extremely easy.

Next, the performance test of the pressure ring according to this embodiment will be described. The test materials are as follows.
Material: Gas nitride sliding surface treatment on SUS440: PVD coating (Cr-N system)
Ring outer diameter: 112mm
Ring axial height (h1): 2.5 mm
Radial thickness of anti-mating part: 4.15 mm
The size of the joint part of each test material is as follows.
Specimen A (Conventional product) Auxiliary dimension a1 = 4.15mm (constant radial thickness)
Specimen B (Comparative Example 1) Joint part size a1 = 3.32 mm
(80% of the thickness in the diameter direction of the anti-mating part)
Specimen C (Invention product 1) Joint portion dimension a1 = 2.905 mm
(70% of the thickness in the diameter direction of the anti-joint part)
Specimen D (Invention Product 2) Joint Size A1 = 2.075mm
(50% of the thickness in the diameter direction of the anti-mating part)
Specimen E (Comparative Example 2) Joint part size a1 = 1.245 mm
(30% of the thickness in the diameter direction of the anti-joint part)
Specimen F (Comparative Example 3) Joint part size a1 = 0.830 mm
(20% of the thickness in the diameter direction of the anti-mating part)

  The surface pressure distribution of each test material was measured and compared using the surface pressure distribution measuring apparatus shown in FIG. As shown in FIG. 3, a part of the cylinder 101 was cut out, a strain gauge 102 was attached to the notch 101a (the thinnest part) of the cylinder 101, and the strain due to contact load of the test material was measured as a surface pressure. While the heaters 104 are attached to the upper and lower sides of the piston 103 that holds the pressure ring to heat the pressure ring, cooling water is supplied to the outer periphery of the cylinder 101 to cool the cylinder 101, and the piston 103 to the cylinder 101 are operated during actual operation. A close temperature gradient was distributed. The test results are shown in Table 1 and graphically shown in FIG. In FIG. 4, the vertical axis represents the surface pressure, and the horizontal axis represents the circumferential angle from the joint portion. In addition, it represented with the surface pressure ratio on the basis of the surface pressure of the joint part of the test material A.

  As can be seen from Table 1 and FIG. 4, the specimens C and D can exhibit the effect of suppressing the increase of the surface pressure that occurs near the joint part during actual operation, and uneven wear, scuff, cracks that are likely to occur near the joint part. It is possible to prevent the peeling of the hard film. Specimen A and Specimen B have large surface pressure ratio ranges of 0.2 to 1.0 and 0.2 to 0.93. Due to the effect of thermal load, sudden surface pressure fluctuations occur near the joint. occured. This tendency is expected to become more prominent when the temperature is raised. On the other hand, the test materials C and D have narrow surface pressure ratio ranges of 0.21 to 0.81 and 0.24 to 0.68, respectively, and the degree of surface pressure fluctuation in the vicinity of the abutment portion is low. Recognize. In addition, the specimens E and F have extremely narrow surface pressure ratio ranges of 0.33 to 0.48 and 0.38 to 0.42, and are excellent in the effect of suppressing the increase in surface pressure, but will be described later. There are problems in assembly.

Next, the stress at the time of mounting was measured about test material AF. The stress at the time of mounting means the stress at the counter-abutting portion when the gap between the abutting end surfaces of the abutting portion is expanded eight times the ring radial direction thickness, and is expressed by the following equation. f ₁ = E · a ₁ (8a ₁ ―m) /2.35 (d? a ₁ ) ² (MPa)
Here, E is the Young's modulus, a ₁ is the thickness in the ring diameter direction at the joint portion, m is the free joint gap, and d is the outer diameter of the ring. Details of the stress at the time of mounting are described in detail in “Piston Ring for Automobile” (author: Editorial Committee for Piston Ring for Automobile) issued by Sankaido Co., Ltd. on October 6, 1997.

  The measurement results are shown in Table 2 and the graph of FIG. In addition, it represented as a stress ratio on the basis of the maximum stress in the anti-abutting part of the test material A. As apparent from Table 2 and FIG. 5, the test materials C and D can keep the maximum stress low compared to the test materials A and B. Although the maximum stresses of the specimens E and F are the lowest, there are problems in assemblability as will be described later.

Next, Table 3 shows the assemblability of the test materials A to E and the test materials G and H. Table 3 also shows the weight ratio based on the weight of the specimen A. The test materials G and H are as follows, and the materials, the sliding surface treatment, the ring outer diameter, the ring axial height, and the radial thickness of the anti-joint portion are the same as those of the test materials A to E. .
Specimen G (Comparative Example 3) Joint portion dimension a1 = 1.922 mm
(48% of the thickness in the diameter direction of the counter joint)
Specimen H (Comparative Example 4) Joint part size a1 = 1.66 mm
(40% of the thickness in the diameter direction of the anti-mating part)

  As can be seen from Table 3, the specimens A to D could be mounted in the ring groove of the piston, but for the specimens G, H, and E, the ring inner circumference inscribed circle is a ring. It became larger than the groove diameter, and the specimen fell off without fitting in the ring groove. Therefore, considering the ease of assembly in the ring groove, the test materials G, H, E and the test material F having a smaller joint portion than the test material E are inappropriate in terms of assembly properties. It can be seen that the assembling property requires that the minimum value of the thickness in the diameter direction of the joint portion is 50% of that of the counter joint portion. The same test was performed for the outer diameter of the ring 86 mm, the radial thickness of the anti-mating portion 2.5 mm, the outer diameter of the ring 135 mm, and the radial thickness of the anti-mating portion 5.4 mm. The test result similar to the said test was obtained by making the thickness of the diameter direction of a joint part into 50 to 70% with respect to the thickness of a diameter direction.

The pressure ring according to the present invention is not limited to the above-described embodiment, and various modifications are possible within the scope described in the claims. For example, in the above-described embodiment, the outer peripheral surface processing is performed by cutting, but grinding by a grinder may be performed instead of cutting.
Further, as the surface treatment, after the outer periphery of the pressure ring material is processed, the entire periphery is subjected to nitriding treatment, and the PVD coating is further formed on the outer peripheral surface side to form the PVD coating on the nitriding treatment layer, or the entire ring material is processed. A nitriding treatment may be applied to the periphery, and then outer periphery processing may be performed to remove the outer nitriding layer, and then a PVD coating may be applied to the outer periphery. The present invention is not limited to a piston ring having a rectangular cross section, but a half keystone ring having a taper only on the upper surface of the ring on the combustion chamber side, and a full keystone ring having a taper on both sides of the combustion chamber side and the anti-combustion chamber side. It can be applied to various rings.

Further, although the steel pressure ring has been described, when the pressure ring is a casting ring, after finishing the pressure ring of a desired shape with a mold in advance, the outer peripheral surface and the inner peripheral surface may be finished.

The top view which shows the pressure ring by embodiment of this invention. Sectional drawing which each shows the conventional pressure ring with constant radial direction thickness, the pressure ring which changed the thickness of the conventional radial direction, and the pressure ring by this Embodiment. Sectional drawing which shows the surface pressure distribution measuring apparatus used for the measurement of the surface pressure distribution of pressure ring sample materials AF. The graph which shows the surface pressure distribution of test material AF. Graph showing stress when mounting test materials A to E, G, H

Explanation of symbols

1: Pressure ring, 2: Inner circumference, 3: Outer circumference, 5: Joint part, 6: Counter-joint part, 8: Center of outer circumference, 9: Center of inner circumference

Claims (2)

The diameter of the ring in the diametric direction of the ring that passes through the end surface of the abutment portion gradually increases from the abutment portion toward the opposite abutment portion that is the diametrically opposite portion of the abutment portion, In the pressure ring with the maximum thickness at the anti-mating part,
In the diametrical direction of the pressure ring passing through the end face of the joint part in a state where the joint part is closed, the thickness of the counter joint part is 2.5 to 5.0% of the outer diameter of the pressure ring,
When the joint portion is closed, the outer periphery and the inner periphery of the pressure ring are both perfect circles, and the center of the outer periphery is more than the center of the inner periphery in the diameter direction of the pressure ring passing through the end face of the joint portion. A pressure ring which is shifted to a counter-abutment portion side, and the thickness in the diameter direction of the abutment portion is 50 to 70% of the thickness in the diameter direction of the counter-abutment portion. Producing a pressure ring material having an outer periphery and an inner periphery such that the thickness in the diametrical direction is substantially constant and having a joint portion; and
The joint portion of the pressure ring material is in a closed state, and in the diameter direction of the pressure ring material passing through the end face of the joint portion from the center position of the closed pressure ring material, Holding the pressure ring material in a cutting machine or a grinding machine in a state where the center of rotation is displaced by a predetermined amount in the direction of a certain abutment portion;
A step of cutting or grinding the outer peripheral surface by rotating the pressure ring material held by the cutting machine or the grinding machine around a rotational center where the pressure ring material is displaced, and the predetermined amount is shaved on the abutment portion side. Pressure corresponding to 1/2 of the machining allowance or grinding allowance, the cutting amount or grinding amount at the abutment portion being the maximum, and the cutting amount or grinding amount at the counter-abutting portion being substantially zero Ring manufacturing method.

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