Quick return cylinder sleeve

Abstract

The present invention provides a quick oil return cylinder liner as an accessory of an automobile engine, which enhances the durability and reliability of high-explosion pressure and high-power engines. The present invention is designed with an oil groove design on the inner diameter surface of the cylinder liner below the lower dead center position of the oil ring. The oil scraped off by the oil ring will be quickly released along the oil groove on the cylinder liner, greatly reducing the risk of the oil remaining on the cylinder liner being scraped up. The design of the oil groove is preferentially concentrated in the direction of the pin hole of the piston, rather than a design in which the oil groove is arranged in a circle, to prevent the increase in skirt contact surface pressure, uneven wear of the piston skirt, increased wear, and even cylinder pulling caused by the reduced contact area between the piston skirt and the oil groove when the piston runs to the lower dead center position. This design does not affect the performance of the piston and is also beneficial to the oil return effect of the engine oil.

Description

Technical Field

[0001] The invention relates to the technical field of engine accessories, in particular to an engine cylinder liner with a quick oil return groove. Background Art

[0002] In recent years, 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 high power have put forward more stringent requirements on engine durability. As one of the core components of the engine, the engine cylinder liner will face higher durability and reliability challenges, such as Figure 1 This is the existing cylinder liner design. The inner diameter of the cylinder liner is a relatively smooth design with a certain honing pattern. The disadvantage of this design is that when the oil ring scrapes the oil to the bottom dead center, the oil accumulated under the oil ring cannot be released well, which will cause the risk of further oil remaining on the cylinder liner being scraped up. As an improvement, there is a solution in the prior art to set an oil return groove below the bottom dead center of the cylinder liner, such as the attached Figure 2 As shown, when the engine oil is scraped to the bottom dead center, it flows into the oil return groove to avoid being brought back to the combustion chamber by the piston. Summary of the invention

[0003] In view of the above problems, the present invention aims to solve at least one of the technical problems in the related art to a certain extent. To this end, the present invention provides a quick oil return cylinder sleeve, which can solve the technical problems in the prior art that the oil cannot be returned to the oil pool in time after being scraped to the bottom dead center position and accumulated.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0005] The rapid oil return cylinder liner is configured as an elongated cylinder having a cylinder liner outer surface and a cylinder liner inner surface. The cylinder liner central axis defined by the cylinder liner inner surface extends between the first cylinder liner axial end and the second cylinder liner axial end. The cylinder liner inner surface is configured to form a combustion chamber together with the piston and the engine housing. The piston is located in the cylinder liner and can move between the top dead center position and the bottom dead center position relative to the cylinder liner. A rapid oil return portion is provided on the cylinder liner inner surface corresponding to the non-skirt portion of the piston, that is, the oil return groove is only provided on the inner surface of the cylinder liner on the side corresponding to the piston pin shaft, and no oil return groove is provided on the cylinder liner inner surface corresponding to the piston skirt. Further, the oil return portion is located: when the piston is at the bottom dead center position, below the position of the cylinder liner inner surface corresponding to the piston oil ring oil blade; and the rapid oil return portion extends to the second cylinder liner axial end and forms an opening at the second cylinder liner axial end. This can effectively avoid the prior art where the swinging piston collides with the oil return groove, causing the piston skirt to be worn.

[0006] Further, the oil return portion is configured as a plurality of oil return grooves extending along the central axis of the cylinder sleeve to the axial end of the second cylinder sleeve. This is the main form of the oil return portion.

[0007] Further, the main cross-section of the oil return groove is set as a rectangle with a depth of a and a width of b, and the distance between two adjacent oil return grooves is c. As a preference, the depth a of the oil return groove > 0.050 mm, the width b > 1.0 mm, and the distance c between two adjacent oil return grooves is set as:

[0008] 1.0 mm < c < 4.3 mm.

[0009] Further, the front view cross-section shape of the oil return groove on the side close to the combustion chamber should be set as semi-circular, square, oval, and other shapes that are conducive to the collapse of the accumulated lubricating oil into the oil return groove, so that the accumulated lubricating oil can more easily collapse into the oil return groove.

[0010] Further, in order to enable the lubricating oil to flow into the oil return groove immediately when it flows in drops or in a stream, it is particularly important to set the distance d between the lower oil edge line of the oil scraping ring blade (i.e., the lowest side circular line formed by the contact between the blade and the cylinder liner) at the lower stop point and the vertex of the oil return groove. After repeated verification, setting the size of d as: 1.75 mm < d < 4.3 mm is most conducive to the return of the lubricating oil.

[0011] Further, the distribution of the oil return part is limited numerically. The direction of the piston pin shaft is set as 0 - 180°. According to the distribution of the piston skirt, the distribution range of the oil return part or the oil return groove is 0 - 45°, 135° - 225°, 315° - 360°, and the number of oil grooves ≥ 2.

[0012] Furthermore, it may relate to a cylinder liner and piston assembly, and the assembly includes:

[0013] The fast oil return cylinder liner as described above;

[0014] A piston, the piston is located in the cylinder liner and can move relative to the cylinder liner between the top dead center position and the bottom dead center position, and includes an upper piston surface and a lower piston surface that form a combustion surface.

[0015] Implementing the technical solution of the present invention has at least the following beneficial effects:

[0016] 1) Below the bottom dead center position of the oil ring, the oil groove design on the inner surface of the cylinder liner enables the oil scraped by the oil ring to quickly flow back along the oil groove, greatly reducing the risk of the oil remaining on the cylinder liner being scraped upward.

[0017] 2) The oil groove is arranged in the direction of the piston pin hole. Since there is no contact between the piston and the cylinder liner in the direction of the piston pin hole, when the piston runs to the bottom dead center position, the design of the piston pin hole direction is hollow, and there will be no contact between the piston and the cylinder liner in this direction, which has no impact on the piston performance. On the other hand, it is also beneficial to the oil return effect of the lubricating oil.

[0018] 3) The oil groove is arranged on the cylinder liner in the direction of the pin control, which avoids the contact between the piston skirt and the oil groove when the entire circumference is filled with oil grooves. Due to the reduction of the contact area at the oil groove, the contact surface pressure of the piston skirt at the bottom dead center will increase, the piston skirt will wear unevenly, and the piston skirt will be scratched over time, which may cause the risk of cylinder pulling.

[0019] 4) The oil tank is connected to the bottom of the cylinder liner, and the oil in the oil tank can be released into the crankcase without accumulating in the oil tank, thus avoiding the risk of the piston and crankshaft rushing up the oil accumulated at the bottom of the oil tank.

[0020] Additional aspects and advantages of the present application will be given in part in the following description, and in part will become obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a side cross-sectional view of an existing cylinder liner design.

[0022] Figure 2 It is a side cross-sectional view of an embodiment of the present invention.

[0023] Figure 3 It is the layout of the cylinder liner oil groove.

[0024] Figure 4 This is the oil tank dimension drawing.

[0025] FIG. 5( a ) shows the state of lubricating oil without the setting of the oil return groove in the prior art.

[0026] FIG. 5( b ) shows the state of the lubricating oil after setting the oil return groove without opening.

[0027] FIG5(c) shows the state of the lubricating oil after the oil return groove is set in this embodiment.

[0028] Description of reference numerals:

[0029] 1-cylinder liner; 10-cylinder liner center axis; 11-cylinder liner outer surface; 12-cylinder liner inner surface; 13-first axial cylinder liner end; 14-second axial cylinder liner end; 15 flange;

[0030] 2- oil return groove; 3- piston; 4- oil ring; 5- piston pin;

[0031] a-depth of the main cross section of the oil return groove; b-width of the main cross section of the oil return groove;

[0032] c- the distance between two adjacent oil return grooves; d- the distance between the lower ring line where the oil edge of the oil ring contacts the cylinder liner and the apex of the oil return groove. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] Those skilled in the art understand that in the cylinder liner and piston assembly, the cylinder liner is an elongated cylinder having a cylinder liner outer surface and a cylinder liner inner surface, the cylinder liner inner surface defining a cylinder liner central axis extending between a first axial cylinder liner end and a second axial cylinder liner end, and the piston moves between a bottom dead center (BDC) position and a top dead center (TDC) position in the engine cylinder liner. In order to achieve lubrication and avoid dry grinding, an oil inlet gap is formed between the top ring and the cylinder liner. In order to prevent the lubricating oil from entering the combustion chamber and causing carbon deposits, an oil ring is provided on the piston. When the piston moves to the bottom dead center, the lubricating oil is scraped back to the crankcase oil pool, thereby limiting the migration of oil from the gap to the combustion chamber.

[0035] As mentioned in the background art, the cylinder liner and piston assembly in the prior art still have certain defects. For example, after the piston oil ring scrapes the lubricating oil back to the bottom dead center position, the lubricating oil flows back by gravity. However, when the engine is just started or the cylinder liner and lubricating oil temperature is not high, the lubricating oil has poor flow performance and accumulates on the cylinder liner at the bottom dead center position, and is easily sucked back into the combustion chamber.

[0036] In the prior art, there are Figure 1 The cylinder liner structure in the embodiment of the present invention, although it is an improvement on the lubricating oil film, actually has a certain impact on the oil return effect. As shown in FIG5(b), the lubricating oil flows back into the groove, and the groove stores the lubricating oil. Compared with FIG5(a) in the prior art without an oil return groove, the risk of back-suction is avoided to a certain extent. However, since the amount of oil contained in the groove is limited, after the groove structure is filled with oil, the oil droplets accumulate again and protrude from the inner surface of the cylinder liner. At this time, when the piston rises from the bottom dead center, it is easy to bring the oil droplets protruding from the bottom of the oil groove back to the inner wall of the cylinder liner, which is not conducive to the lubricating oil returning to the crankcase oil pool.

[0037] In view of the above problems, the present invention improves the cylinder liner structure, ensures the lubrication effect, makes the oil return smoothly in the cylinder liner, and avoids the problem of lubricating oil rising to the combustion chamber and causing carbon deposition. The specific technical solution is described below.

[0038] Please refer to the attached Figure 1 to Figure 2 As shown, in some embodiments of the present application, a cylinder liner with rapid oil return is provided, which is applied to the cylinder liner and piston assembly of the engine to further improve the oil return condition of the engine cylinder liner.

[0039] The cylinder liner 1 comprises an elongated cylindrical body having a liner outer surface 11 and a liner inner surface 12, the liner inner surface 12 defining a liner central axis 10 extending between a first axial liner end 13 and a second axial liner end 14. The elongated cylindrical body further comprises a flange 15 projecting radially outwardly on the first axial liner end 13. Figure 1 In the figure, the inner surface 12 of the cylinder liner 1 provides a surface to support the reciprocating movement of the piston. The upper limit position of the piston is the top dead center (TDC) position, and the lower limit position is the bottom dead center (BDC). An oil inlet gap is formed between the piston and the cylinder liner. An oil ring is provided on the piston to scrape the lubricating oil back to the crankcase oil pool.

[0040] During the operation of the piston, the lubricating oil is scraped to the bottom dead center position, and the lubricating oil flows back to the crankcase oil pool along the cylinder liner wall by gravity. However, the fluidity of the lubricating oil at a low temperature is not sufficient to flow completely and smoothly and drip back to the oil pool.

[0041] As a solution, in order to smoothly guide the scraped lubricating oil back to the oil pool, such as Figure 1 In this embodiment, a groove structure oil return groove 2 is provided at the bottom of the cylinder liner. The highest point of the oil return groove 2 in the direction of the central axis 10 is located at a distance d below the lower ring line where the oil edge of the oil ring contacts the inner surface 12 of the cylinder liner when the piston is at the bottom dead center position. That is to say, the highest point of the oil return groove 2 can just receive the lubricating oil scraped off the inner surface 12 of the cylinder liner by the oil ring.

[0042] In this way, the technical problem of lubricating oil back-absorption can be effectively solved. However, it should be emphasized that the oil return grooves arranged on the cylinder sleeve reduce the contact area between the piston skirt and the cylinder sleeve during the reciprocating operation of the piston, and when the piston swings during operation, the piston skirt contacts the non-smooth surface, which easily causes damage to the piston skirt, resulting in the shedding of the coating. The damaged piston skirt contacts the cylinder sleeve and further scratches the cylinder sleeve, which seriously causes cylinder pulling. Therefore, in the present embodiment, a quick oil return portion is provided on the inner surface of the cylinder sleeve corresponding to the non-skirt portion of the piston, that is, the oil return groove 2 is only provided on the inner surface 12 of the cylinder sleeve corresponding to the side of the piston pin shaft, and no oil return groove is provided on the inner surface of the cylinder sleeve corresponding to the piston skirt, and the oil return groove 2 is directly connected to the second axial cylinder sleeve end surface 14 of the cylinder sleeve to guide the lubricating oil to drip smoothly into the crankcase oil pool.

[0043] In order to better understand the distribution position of the oil return groove 2, as shown in the attached Figure 4As shown, the setting range of the oil return groove is described in terms of angle: with the piston pin axis direction being 0-180°, according to the distribution of the piston skirt, the preferred distribution range of the oil return groove 2 is 0-45°, 135°-225°, 315°-360°. According to different designs of the piston skirt, this range can be appropriately adjusted. For example, the main thrust surface and the secondary thrust surface of some pistons are of different sizes, so that the size of the piston skirt is designed differently. The position range of the oil return groove can be flexibly adjusted according to the size of the piston skirt, for example, 0-55°, 125°-215°, 325°-360°. The maximum range is limited based on not causing wear to the piston skirt.

[0044] In order to obtain more reasonable parameter data, reasonable experimental verification is essential. In this embodiment, the distance between the lower ring line where the oil ring oil blade contacts the inner surface 12 of the cylinder liner at the bottom dead center and the top of the oil return groove 2 is set to d, and the front cross-sectional shape of the oil return groove close to the combustion chamber side is semicircular, square, or elliptical, so as to form a shape setting that is easy to guide the lubricating oil to return, and experimental verification is carried out for the size of d and the top shape of the oil return groove. Considering the low-temperature fluidity and high-temperature viscosity of the lubricating oil, the most commonly used motor oil in automobiles, 5W-30, is used as the experimental lubricating oil. According to the fluidity research of the lubricating oil in strands and drops at low and high temperatures, further, according to the thickness of the lubricating oil film and the experimental results of the thickness that can be affected by the reciprocating motion of the piston (the experimental process will not be repeated), the size of d is set within the range of 1.75mm-4.3mm. When d is 1.75mm, the lubricating oil is scraped back and accumulated by the oil ring. After the oil film is formed, the redundant height forms a flowing liquid flow, and the stranded and droplet-forming lubricating oil flow is promptly collapsed into the groove. At the same time, when the piston moves to the upper dead center, since the distance of 1.75mm between the oil ring and the remaining ring bank is reasonably set, the scraped lubricating oil has flowed into the oil return groove when it forms oil droplets or strands, that is, at the moment when the piston stops at the lower dead center, and will not accumulate or the accumulation height will touch the side of the piston. Therefore, the generated suction airflow will suck back and bring back a very small amount of lubricating oil. However, when it is less than 1.75mm, since the position of the oil return groove 2 is close to the oil ring and far from the edge of the remaining ring bank, although the scraped lubricating oil has flowed into the oil return groove 2, the back-carrying airflow generated by the piston and the negative pressure generated by the oil ring cause obvious back-carrying phenomenon. The closer to the bottom dead center oil ring, the more serious the back-carrying phenomenon.

[0045] Continue to move downward back to the upper apex of the oil groove 2, when it is 4.3mm away from the bottom dead center oil ring position on the inner surface of the cylinder liner, the scraped lubricating oil has formed oil droplets higher than the oil film on the inner surface 12 of the cylinder liner, or the lubricating oil that has flowed in streams has reached the piston surface. In these two states, the lubricating oil accumulated on the cylinder liner can easily be brought back to the top dead center or even sucked back into the combustion chamber by the negative pressure generated by the oil ring seal.

[0046] Considering the properties of lubricating oil in forming oil film and droplets, in order to make it easier for lubricating oil to flow into the oil return groove 2, it should be clear that the depth a and width b of the oil return groove 2 and the spacing c between two adjacent oil grooves should be further set. The setting of the oil groove parameters depth a and width b and the spacing c of the oil grooves is still mainly based on the means of controlling the accumulation of lubricating oil into droplets, so that it collapses and gathers into strands in time and flows down from the oil return groove 2 before accumulating into droplets. Figure 4 The cross-sectional view of the oil return groove 2 is shown, wherein the oil groove dimensions are defined as follows:

[0047] a>0.050mm;

[0048] b>1.0mm.

[0049] The distance c between two adjacent oil return grooves is set as:

[0050] 1.0mm <c<4.3mm。

[0051] <Industrial Applicability>

[0052] For an overall comparison of the experiments, please refer to the attached Figure 5(a)-5(c) The diagram shows the accumulation and flow of lubricating oil when the piston without an oil return groove and with an oil return groove runs to the bottom dead center. FIG5(a) shows the prior art without the provision of an oil return groove. It can be seen that the lubricating oil scraped back from the inner surface of the cylinder liner accumulates on the lower side of the oil ring at the bottom dead center and is easily sucked back and entrained when the oil ring moves upward.

[0053] Figure 5(b) shows the state of the lubricating oil after the oil return groove without opening is set. After the engine is running, the oil ring scrapes the lubricating oil down to the position below the oil ring at the bottom dead center of the piston. Due to the setting of the oil return groove, the lubricating oil accumulates and flows into drops or streams and flows back to the oil return groove, and accumulates in the oil return groove. When the fluidity of the lubricating oil does not meet the expected requirements, the accumulation protrudes from the cylinder liner. The lubricating oil droplets in this suspended and attached state will inevitably be scraped back and carried back under the negative pressure generated by the rising of the piston and the scraper ring.

[0054] FIG5(c) shows the state of the lubricating oil after the oil return groove of this embodiment is set. After the engine is running, the oil ring scrapes the lubricating oil down to the position below the oil ring at the bottom dead center of the piston. Due to the reasonable setting, when the lubricating oil accumulates into drops or flows into streams, its volume has covered the oil return groove, causing the oil droplets to collapse into the oil return groove, and after accumulation, they smoothly flow into the oil return groove and flow back to the crankcase along the oil return groove by gravity. This solution also avoids the scraping and carrying back caused by the solution of FIG5(b).

[0055] The parts of the present invention that are not described in detail are well-known technologies for those skilled in the art. Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention is described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some of the technical features therein by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A quick oil return cylinder liner, the cylinder liner (1) being an elongated cylinder having a cylinder liner outer surface (11) and a cylinder liner inner surface (12), the cylinder liner inner surface (12) defining a cylinder liner central axis (10) extending between a first cylinder liner axial end (13) and a second cylinder liner axial end (14), the cylinder liner inner surface (12) being configured to form a combustion chamber together with a piston (3) and an engine housing, the piston (3) being located in the cylinder liner (1) and being movable relative to the cylinder liner between a top dead center position and a bottom dead center position, the piston (3) being provided with an oil ring (4), characterized in that: A quick oil return portion is provided on the inner surface of the cylinder sleeve corresponding to the non-skirt portion of the piston, wherein the oil return portion is located below the inner surface of the cylinder sleeve corresponding to the oil blade of the piston oil ring (4) when the piston (3) is at the bottom dead center position; The rapid oil return portion extends to the axial end (14) of the second cylinder liner and forms an opening at the axial end (14) of the second cylinder liner; The oil return portion is a plurality of oil return grooves (2) extending along the central axis (10) of the cylinder liner to the axial end (14) of the second cylinder liner.

2. The rapid oil return cylinder sleeve according to claim 1, characterized in that: The main cross-section of the oil return groove (2) is set to be a rectangle with a depth of a and a width of b, and there is a distance c between two adjacent oil return grooves.

3. The rapid oil return cylinder sleeve according to claim 2, characterized in that: The depth a of the oil return groove (2) is greater than 0.050 mm, the width b is greater than 1.0 mm, and the distance c between two adjacent oil return grooves is set to: 1.0mm <c<4.3mm。 4. The rapid oil return cylinder sleeve according to claim 2, characterized in that: The front cross-sectional shape of the oil return groove (2) close to the combustion chamber side is semicircular, square or elliptical.

5. The rapid oil return cylinder sleeve according to claim 2, characterized in that: When the piston is at the bottom dead center, the distance between the lower ring line where the oil edge of the oil ring contacts the inner surface (12) of the cylinder sleeve and the vertex of the oil return groove (2) is d, and the size of d is set to: 1.75mm <d<4.3mm。 6. The rapid oil return cylinder sleeve according to any one of claims 2 to 5, characterized in that: The piston pin axis direction is 0-180°. According to the distribution of the piston skirt, the distribution range of the oil return groove (2) or the oil return part is 0-45°, 135°-225°, 315°-360°, and the number of oil grooves is ≥2.

7. A cylinder liner and piston assembly, characterized in that: The components include: A cylinder liner, wherein the cylinder liner is a rapid oil return cylinder liner according to any one of claims 1 to 6; The piston is located in the cylinder sleeve and can move between a top dead center position and a bottom dead center position relative to the cylinder sleeve, and includes an upper piston surface and a lower piston surface forming a combustion surface.

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