A double-edge positive-twist oil ring assembly

Abstract

The present application provides a double-edge positive-twist oil ring assembly. By setting the radial thickness of the upper oil edge to be larger than that of the lower oil edge, and the distance from the central axis of the support spring to the upper surface of the oil ring is greater than the distance to the lower surface of the oil ring, and further optimizing this scheme, the torsional stress state of the oil ring is greatly improved, thus well ensuring that the oil ring can produce the effects of positive twist and large contact surface pressure of the lower oil scraping edge, greatly improving the oil scraping effect; further facilitating oil sealing, reducing the risk of oil creeping upwards, and reducing oil consumption.

Description

Technical Field

[0001] This application belongs to the field of automotive engine parts, and particularly relates to a double-edge positive-twist oil ring assembly. Background Art

[0002] High burst pressure and high power will be one of the main features of the next-generation engine technology upgrade, and high burst pressure and power pose more stringent requirements for engine durability. As one of the core components of the engine, the engine piston ring will face challenges of higher durability and reliability requirements.

[0003] As shown in Figure 1(a), which is a cross-sectional view of the existing one-piece double-edge oil ring. It can be seen that the upper scraping edge and the lower scraping edge are designed with equal distances in the radial thickness direction. Due to the deformation of the cylinder liner during engine operation, when the oil ring fits with the cylinder liner, it will be affected by the deformation of the cylinder liner, resulting in uncontrollable tilting during movement. In this case, the scraping effect of the scraping edge will be affected. Moreover, the upper side of the two-piece oil ring and the upper side of the ring groove are designed to be parallel. Affected by the deformation of the ring groove and the movement deformation of the ring, the fit between the ring and the ring groove will be affected, and the side seal between the ring and the ring groove will also be affected.

[0004] As an improvement, an improved double-edge oil ring is proposed in the prior art. As shown in Figure 1(b), the radial thicknesses of the upper and lower scraping edges are unequal, generating unequal surface pressures and causing the oil ring to twist. In actual operating conditions, due to the rigidity of the oil ring and the good lubrication of the cylinder liner, generally, the frictional force between the scraping edge and the cylinder liner is not sufficient to achieve the torsion of the single-piece double-edge ring. If the radial thickness difference Δr of the two scraping edges is designed according to the working conditions of each type of engine, the process is complex and cumbersome. And if the radial thickness difference Δr of the scraping edge is unreasonable, it will instead cause only one scraping edge to work. Therefore, this simple setting of changing the radial height of the scraping edge will greatly reduce the scraping effect because the torsion effect fails to meet the expectations. Summary of the Invention

[0005] To solve or improve the problems mentioned in the background art, this application provides a double-edge positive-twist oil ring assembly, including a double-edge oil ring and a support spring. The oil ring includes an upper oil edge, a lower oil edge, and a ring body. The upper oil edge and the lower oil edge respectively have radial thicknesses r1 and r2. The distance from the central axis of the support spring to the upper surface of the oil ring is h1, and the distance to the lower surface of the oil ring is h2. Among them, the relationship between the radial thickness r1 of the upper oil edge and the radial thickness r2 of the lower oil edge is: r1 > r2, and the relationship between the distance h1 from the central axis of the support spring to the upper surface of the oil ring and the distance h2 to the lower surface is: h1 > h2.

[0006] According to the above solution, further, the relationship between the radial thickness r1 of the upper oil edge and the radial thickness r2 of the lower oil edge is: r1 ≥ r1 + 0.01 mm, or r1 / r2 ≥ 1.002.

[0007] According to the above solution, further, when the height difference Δh between the distance h1 from the central axis of the support spring to the upper surface of the oil ring and the distance h2 to the lower surface is 0.3 mm - 0.7 mm, the radial thickness difference Δr between the radial thickness r1 of the upper oil edge and the radial thickness r2 of the lower oil edge is set to 0.012 - 0.030 mm. Preferably, when the height difference Δh is 0.6 mm, the radial thickness difference Δr of the radial thickness r2 is set to 0.02 mm.

[0008] According to the above solution, further, the relationship between the thickness rh1 of the upper oil edge and the thickness rh2 of the lower oil edge is set as: rh1 < rh2.

[0009] According to the above solution, further, a PVD or DLC coating is provided on the lower oil edge.

[0010] For the single-piece double-edge positive-twist oil ring provided in this application, when setting the radial height difference Δh between the upper and lower oil edges, the position of the support spring is adjusted, greatly improving the torsional stress state of the oil ring. Thus, there are at least the following verified technical effects:

[0011] 1. The downward oil scraping of the oil ring is mainly affected by the lower oil scraping edge. The contact surface pressure of the lower oil scraping edge is large. Compared with the design of equal surface pressure for the upper and lower oil scraping edges, to a certain extent, the oil ring with non-equal surface pressure has a better oil scraping effect on the ring. Further, by optimizing the position of the spring and combining with the spacing difference of the oil scraping edges, the positive twist of the oil ring and the large contact surface pressure of the lower oil scraping edge can be well ensured, greatly improving the oil scraping effect;

[0012] 2. The positive-twist two-piece oil ring will form a side sealing effect between the ring and the ring groove, which is beneficial for sealing oil, reducing the risk of engine oil leaking upwards, and reducing engine oil consumption;

[0013] 3. Since the contact surface pressure of the lower oil scraping edge of the oil ring is larger than that of the upper oil scraping edge, and with the protection of coatings such as PVD and DLC, the oil scraping effect and the oil sealing effect are more significant. Description of the Drawings

[0014] Figure 1(a) shows an integral double-edge oil ring according to the prior art.

[0015] Figure 1(b) shows a positive-twist oil ring improved according to the prior art.

[0016] Figure 2 Shows the positive-twist oil ring of the embodiment of this application.

[0017] Figure 3 Shows the deflection state of the positive-twist oil ring of the embodiment of this application during operation.

[0018] Figure 4Shows the relationship between the twist angle of the ring and the radial distance between the upper and lower oil scraping edges.

[0019] Description of Reference Numerals

[0020] 1 Oil ring; 11 Upper oil scraping edge; 12 Lower oil scraping edge;

[0021] 2 Supporting spring; 3 Cylinder liner; 4 Piston; Detailed Embodiment

[0022] The exemplary embodiments of the present application will be described below with reference to the accompanying drawings. It should be understood that these specific descriptions are only used to teach those skilled in the art how to implement the present application, rather than to exhaust all feasible ways of the present application, nor to limit the scope of the present application.

[0023] The function of the piston ring is to ensure the sealing effect of the engine, prevent the leakage of fuel gas, and has a great impact on the engine performance. The piston ring is divided into two types: air ring and oil ring. The function of the air ring is to ensure the seal between the piston and the cylinder, and is used to seal the compressed air in the combustion chamber; the oil ring is used to scrape off the excess engine oil on the cylinder, which can prevent the engine oil from entering the cylinder and being sintered into carbon deposits. High explosion pressure and high power will be one of the main features of the next-generation engine technology upgrade, and high explosion pressure and power pose more stringent requirements for the engine durability. As one of the core components of the engine, the engine piston ring will face challenges of higher durability and reliability requirements.

[0024] As is well known, the existing oil scraping rings are of integral type and combined type. The integral double-edge oil ring includes upper and lower oil scraping edges to ensure the oil scraping effect. As shown in Fig. 1(a), it is a cross-sectional view of the currently existing two-piece oil ring. The upper oil scraping edge and the lower oil scraping edge are designed to be equidistant in the radial thickness direction. During the operation of the engine, the cylinder liner is deformed. Therefore, when the oil ring runs in contact with the cylinder liner, it will be affected by the deformation of the cylinder liner and tilt uncontrollably, which will affect the oil scraping effect of the lower oil scraping edge. Furthermore, the fit between the ring and the ring groove will be affected, and the side seal between the ring and the ring groove will be affected.

[0025] As an improvement, in Fig. 1(b), the radial thickness of the upper and lower oil scraping edges is adjusted, and the radial thickness of the lower oil scraping edge is reduced, so that the two oil edges have unequal surface pressures and generate twists. In the actual operating conditions, due to the rigidity of the oil ring and the good lubrication of the cylinder liner, generally, it is very difficult to grasp this radial thickness difference Δr, and relying on the friction force between the oil edge and the cylinder liner is not enough to achieve the torsion of the single-piece double-edge ring. Instead, it will cause only one oil edge to work. Therefore, this setting that simply changes the radial height of the oil edge, due to the torsion effect not reaching the expected value, greatly reduces the oil scraping effect.

[0026] Therefore, in view of the technical problems existing in the above solutions, through the exploration of the actual working conditions of the piston ring, the present application provides a double-edge oil ring that can generate effective positive twist. The specific solution is as follows:

[0027] As a double-edge positive-twist oil ring assembly in the prior art: it includes a double-edge oil ring 1 and a support spring 2. The oil ring 1 mainly includes an upper oil edge 11, a lower oil edge 12, and a ring body 13. The upper oil edge 11 and the lower oil edge 12 have radial thicknesses r1 and r2 respectively. During the operation of the oil ring, when the piston moves downward to scrape oil, due to the action of friction, it twists and deflects, causing the upper oil edge to be suspended, seriously affecting the oil scraping effect. To alleviate or avoid this situation, as an improvement, the radial thicknesses of the two oil edges are set as: the radial thickness r1 of the upper oil edge 11 is greater than the radial thickness r2 of the lower oil edge 12, that is, r1 > r2. However, experiments have found that this improvement is greatly affected by different working conditions. Simply put, different cylinder bores will cause the recalculation of the interpolation of r1 and r2, and this calculation and verification process is cumbersome and it is difficult to form a relatively simple adaptation design. Further research has found that the main reason for the difficult adaptation is that the working conditions of the piston oil ring under different working conditions are different. Thus, in some working conditions, when the oil ring moves downward, the friction force is insufficient to cause the oil ring to flip or deflect, and the lower oil edge 12 cannot contact the cylinder liner, resulting in the loss of oil scraping ability and affecting the oil scraping effect.

[0028] To further improve the deflection or flipping ability of the oil ring, the solution of this embodiment further proposes an improvement. As shown in the attached Figure 2 structure, the distance from the central axis of the support spring 2 to the upper surface of the oil ring 1 is set as h1, and the distance to the lower surface of the oil ring 2 is set as h2. Since the support spring provides a supporting force for the oil ring, enabling it to fit on the cylinder liner with a certain pre-tightening force. Therefore, in order to provide a prestress to help the oil ring flip, so that it can deflect under the action of a small friction force in a well-lubricated state, and the good oil scraping effect in the deflected state is as shown in the attached Figure 3 figure. According to the setting of the oil ring assembly, this prestress is provided by the support spring 2.

[0029] In the prior art, the distances from the center line of the support spring 2 of the oil ring 1 to the upper and lower surfaces of the oil ring are the same, that is, h1 = h2. Although the prestress provided by the support spring 2 in this state can also apply a torsional torque to the oil ring 1, due to the stiffness of the oil ring, the setting of h1 = h2 cannot cause the oil ring to produce a deflection effect. To provide sufficient deflection torque for the deflection of the oil ring, move the position of the support spring 2 relative to the oil ring 1 downward, so that the distance h1 from the center line of the support spring to the upper surface of the oil ring 1 is greater than the distance h2 to the lower surface, that is, h1 > h2.

[0030] Based on the above structural adjustment, further experimental verification and optimization of the rationality of the above adjustment were carried out. The experiment was designed by the method of controlling variables. First, the known settings were that the radial thickness r1 of the upper oil edge was greater than the radial thickness r2 of the lower oil edge, and the distance h1 from the central axis of the support spring 2 to the upper surface of the oil ring 1 was greater than the distance h2 to the lower surface of the oil ring 2. Then, according to the commonly used materials of piston oil rings, theoretical calculations and simulations were carried out. In order to ensure the twisting space, r1 = r2 + 0.01 mm was set to remain unchanged. Starting from h1 = h2 as the control experimental group, with the center line of the support spring displaced downward by 0.05 mm as the unit and Δh as the difference of 0.1 mm, ten groups of oil rings with h1 = h2 + 0.1 mm, h1 = h2 + 0.2 mm, h1 = h2 + 0.3 mm......h1 = h2 + 1 mm were designed as simulation objects in turn. The torque provided by the pre-tightening force of the support spring 2 increased linearly in turn. That is to say, the closer to the lower surface, the better the twisting effect. Keeping h1 = h2 + 0.6 mm with the best twisting effect unchanged, the difference between r1 and r2 was adjusted, with the difference changed by Δr = 0.002 mm. r1 = r2 + 0.008 mm, r1 = r2 + 0.01 mm, r1 = r2 + 0.012 mm, r1 = r2 + 0.018 mm......r1 = r2 + 0.05 mm were set. It was found that when r1 - r2 < 0.01 mm, due to the small difference between the two oil edges, when the piston moved downward, the deformation generated by the twisting of the oil ring was greater than the budget value of the upper oil edge breaking away from the cylinder liner in theory, making this kind of optimization meaningless. When r1 = r2 + 0.04 mm, the twisting deformation still could not make the lower oil edge 12 contact with the cylinder liner. That is, when the difference between the two was greater than 0.04 mm, this kind of design also did not work. Therefore, during the actual experimental verification, with r1 = r2 + 0.01 mm as the reference limit, r1 = r2 + 0.008 mm, r1 = r2 + 0.01 mm, r1 = r2 + 0.014 mm, r1 = r2 + 0.018 mm, r1 = r2 + 0.022 mm, r1 = r2 + 0.026 mm, r1 = r2 + 0.030 mm, r1 = r2 + 0.033 mm, r1 = r2 + 0.036 mm were designed as the verification scheme.

[0031] When the combination of the radial thickness difference Δr of the oil edge and the height difference Δh of the position distance of the center line of the supporting spring occurs, since the height difference Δh between h1 and h2 is set to 1 mm, the supporting spring groove on the oil ring is too close to the bottom of the oil ring, making the overall structural rationality of the oil ring poor, resulting in great difficulty in manufacturing the sample parts, and the strength performance cannot meet the actual working conditions. Therefore, the upper limit of this difference is set to 0.7 mm, and the experimental verification values are set to h1 = h2 + 0.1 mm, h1 = h2 + 0.2 mm... h1 = h2 + 0.7 mm, a total of 7 groups. So far, the number of oil ring sample parts actually experimentally verified is 9 values of the radial thickness difference Δr and 7 values of the height difference Δh. As the effect control group, with the height difference Δh being 0, that is, without changing the middle position of the center axis of the supporting spring as the reference group, there are a total of 72 groups of verification experiments.

[0032] The process of experimental verification will not be elaborated here. After the experimental set time of the engine standard experimental conditions, check the remaining situation of the marks on the inner wall of the cylinder liner. The remaining amount of the marker can be obtained by the area obtained through image processing of the image obtained by photographing the circumferential direction of the cylinder liner ring, and the verification effect can be obtained. After comparing the results, when the radial thickness difference Δr is determined, the greater the height difference Δh of the center line of the supporting spring 2, the less the remaining amount of the marker on the inner wall of the cylinder liner, that is, the better the oil scraping effect. This further confirms the pre-tightening force of the supporting spring 2 on the oil scraping ring 1 in the simulation result, thus generating the prestress for the torsion or deflection of the oil ring.

[0033] When the height difference Δh of the center line of the supporting spring remains unchanged, the oil scraping effect does not change linearly with the increase of the thickness difference Δr of the radial thickness. In the experimental results, it is combined with the radial thickness difference Δr. As shown in the appendix Figure 4 As shown, where the vertical axis is the standard area converted from the remaining amount of the marker. It can be clearly seen from the image that the oil scraping effect curves obtained by various combinations all overlap. The reason for the intersection may be the real intersection of the oil scraping effect or the area measurement error, but the overall law conforms to the simulation calculation expectation. When the height difference Δh is 0.6 mm, between the values of the radial thickness difference Δr of 0.014 - 0.026 mm, the lowest point is obtained. Therefore, the data of the radial thickness difference Δr is set to 0.02 mm to manufacture the sample parts for further verification. Under the same experimental parameters, as shown in the appendix Figure 4 At the position marked by the asterisk after four verifications, the expected better effect is indeed obtained.

[0034] When the height difference Δh is 0.1 mm, that is, when the center axis of the supporting spring moves down 0.05 mm, when the radial thickness difference is 0.008 mm, due to the deflection of the piston ring, the upper oil edge disengages from the cylinder liner, and the oil scraping effect is not good. As the radial thickness difference Δr increases, the two oil edges cooperate to scrape oil, and the effect is good. Continuing to increase the radial thickness difference Δr, due to the insufficient deflection torque provided by the supporting spring, during operation, the lower oil edge 12 cannot contact the cylinder liner, and the oil scraping effect becomes worse.

[0035] As the height difference Δh increases, the provided torque increases, and the trend of the oil scraping effect with the change of the radial thickness difference Δr is not very different. However, when the height difference Δh exceeds 0.6 mm, that is, when the central axis of the support spring moves downward by 0.3 mm, when the radial thickness difference Δr exceeds 0.033 mm, the oil scraping effect becomes worse, even worse than when the height difference is 0.5, and when the height difference Δh is 0.7, the focus even advances to a radial thickness difference of 0.014 mm. The reason is that the greater the height difference, the greater the torque provided by the support spring. During operation, the lower oil edge 12 is squeezed against the cylinder wall, and the upper oil edge 11 disengages from the cylinder wall under the torque provided by the frictional force, resulting in a worse oil scraping effect.

[0036] It can be determined that when the height difference Δh between the distance h1 from the central axis of the support spring to the upper surface of the oil ring and the distance h2 to the lower surface is 0.3 mm - 0.7 mm, that is, when the central axis of the support spring moves downward by 0.2 mm - 0.35 mm, and the radial thickness difference Δr between the radial thickness r1 of the upper oil edge and the radial thickness r2 of the lower oil edge is set to 0.01 - 0.03 mm, it is considered that a better oil scraping effect can be obtained. Preferably, when the height difference Δh is 0.6 mm, the radial thickness difference Δr of the radial thickness r2 is set to 0.014 - 0.026 mm. As a general setting, further, r1 ≥ r2 + 0.01 mm, or r1 / r2 ≥ 1.002.

[0037] For further optimization, in this embodiment, it is further proposed that since the oil ring deflects and swings during operation, therefore, the thickness of the upper oil edge 11 affects the deflection and swing effect of the oil ring. Therefore, in this embodiment, the thickness of the upper oil edge 11 is further reduced. In order to ensure the strength of the oil edge, only the thickness of the upper oil edge 11 can be reduced, while keeping the thickness of the lower oil edge 12, or reducing the thickness of the upper oil edge 11 and increasing the thickness of the lower oil edge 12. But as a general solution, the relationship between the thickness rh1 of the upper oil edge and the thickness rh2 of the lower oil edge is set as:

[0038] rh1 < rh2.

[0039] The advantage of this setting is that it further matches the magnitude of the torque generated by the downward movement of the central axis of the support spring. In the limited space for setting the downward movement of the central axis of the support spring, a greater torque is provided.

[0040] In order to further improve the service life of the oil ring and make the positive-twist oil ring of the above embodiment applicable to various working conditions, the contact surface pressure of the lower oil scraping edge of the oil ring is greater than that of the upper oil scraping edge. As an improvement, a coating is used to protect the lower oil edge, and PVD, DLC and other coatings are preferably used for the oil scraping edge of the oil ring.

[0041] The one-piece positive-twist oil ring provided by this application has the following advantages:

[0042] 1. The downward oil scraping of the oil ring is mainly affected by the lower oil scraping edge. The contact surface pressure of the lower oil scraping edge is large. Compared with the design with equal surface pressure for the upper and lower oil scraping edges, to a certain extent, the oil ring with unequal surface pressure has a better oil scraping effect on the ring. Further, by optimizing the position of the spring and combining with the spacing difference of the oil scraping edges, the positive twist of the oil ring and the large contact surface pressure of the lower oil scraping edge can be well ensured, greatly improving the oil scraping effect.

[0043] 2. The positive twist two-piece oil ring will form a side sealing effect between the ring and the ring groove, which is beneficial to sealing oil, reducing the risk of oil leaking upwards, and reducing oil consumption.

[0044] 3. Since the contact surface pressure of the lower oil scraping edge of the oil ring is larger than that of the upper oil scraping edge, and with the protection of coatings such as PVD and DLC, the oil scraping effect and the oil sealing effect are more remarkable.

[0045] The above is the preferred embodiment of the present application. It should be noted that for those skilled in the art, without departing from the principle of the present application, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present application.

Claims

1. A double-edge positive-twist oil ring assembly: It includes a double-edge oil ring (1) and a supporting spring (2). The double-edge oil ring (1) comprises an upper oil edge (11), a lower oil edge (12), and a ring body (13). The upper oil edge (11) and the lower oil edge (12) have radial thicknesses r1 and r2 respectively. The distance from the central axis of the supporting spring (2) to the upper surface of the oil ring (1) is h1, and the distance to the lower surface of the oil ring (1) is h2. It is characterized in that, The relationship between the radial thickness r1 of the upper oil edge (11) and the radial thickness r2 of the lower oil edge (12) is: r1>r2， And the outer peripheral surface of the upper oil edge (11) exceeds the outer peripheral surface of the lower oil edge (12) in the radial direction of the oil ring; The relationship between the distance h1 from the central axis of the supporting spring (2) to the upper surface of the oil ring (1) and the distance h2 to the lower surface of the oil ring (1) is: h1 > h2.

2. The double-edge positive-twist oil ring assembly according to claim 1, wherein The relationship between the radial thickness r1 of the upper oil edge (11) and the radial thickness r2 of the lower oil edge (12) is: r1 ≥ r2 + 0.01 mm, or r1 / r2 ≥ 1.

002.

3. The double-edge positive-twist oil ring assembly according to claim 1, wherein When the height difference Δh between the distance h1 from the central axis of the supporting spring (2) to the upper surface of the oil ring (1) and the distance h2 to the lower surface of the oil ring (1) is 0.3 mm - 0.7 mm, the radial thickness difference Δr between the radial thickness r1 of the upper oil edge (11) and the radial thickness r2 of the lower oil edge (12) is set to 0.012 - 0.030 mm.

4. The double-edge positive-twist oil ring assembly according to claim 3, wherein, The height difference Δh between the distance h1 from the central axis of the supporting spring (2) to the upper surface of the oil ring (1) and the distance h2 to the lower surface of the oil ring (1) is 0.6 mm.

5. The double-edge positive-twist oil ring assembly according to claim 4, characterized in that, The radial thickness difference Δr is set to 0.02 mm.

6. The double-edge positive-twist oil ring assembly according to any one of claims 1-5, characterized in that, Set the relationship between the thickness rh1 of the upper oil edge and the thickness rh2 of the lower oil edge as: rh1 < rh2.

7. The double-edge positive-twist oil ring assembly according to any one of claims 1-5, characterized in that, Apply a PVD or DLC coating to the lower oil edge.

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