A piston with asymmetric skirt and engine

Abstract

The invention discloses an asymmetric skirt piston and an engine, which relate to the field of engine pistons and include a piston skirt. The side surface of the piston skirt is evenly divided into a thrust side surface and a reverse thrust side surface. The invention has a simple and novel structure. According to the different amounts of thermal expansion of the thrust side surface and the reverse thrust side surface of the piston skirt during the operation of the engine, the invention designs the arc formed by the thrust side surface and the reverse thrust side surface of the piston skirt into an asymmetric form, thereby increasing the reduction amount of the piston thrust side skirt, so that during the operation of the engine, the reduction amount of the piston thrust side surface is offset by the expansion amount after heating, so that the gap between the thrust side surface of the piston skirt and the cylinder barrel can be within a reasonable range, thereby reducing the possibility of contact between the thrust side surface of the piston skirt and the cylinder barrel, thereby reducing the friction generated by the contact between the piston and the cylinder barrel and the combustion load of the engine.

Description

Technical Field

[0001] The invention relates to the field of engine pistons, in particular to an asymmetric skirt piston and an engine. Background Art

[0002] When the piston is running in the engine cylinder, the skirt expands due to heat and its diameter increases. In order to prevent the skirt from coming into strong contact with the cylinder and to avoid the deterioration of the piston's running posture or even cylinder pulling, a profile is often designed for the skirt. The profile design is generally symmetrical.

[0003] In some cases where the temperature is too high or the piston swings too much, when a symmetrical profile design is used, the gap between the piston and the cylinder will appear to be too small on the thrust side, resulting in strong contact between the piston thrust side skirt and the cylinder, excessive friction, deterioration of the piston running posture, and heavy engine combustion load. Summary of the invention

[0004] The object of the present invention is to provide a piston with an asymmetric skirt and an engine, which solves the problems raised in the above-mentioned background technology by designing the arc formed by the thrust side and the reverse thrust side of the piston skirt into a partially asymmetric form.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A skirt asymmetric piston comprises a piston skirt, wherein the side surface of the piston skirt is evenly divided into a thrust side surface and a reverse thrust side surface, wherein the horizontal distance between the highest point of the arc formed by the thrust side surface and the highest point of the arc formed by the reverse thrust side surface in the piston skirt is the basic diameter D0 of the piston, wherein the straight line where the basic diameter is located divides the arc of the thrust side surface into a first profile line and a second profile line connected to the front and rear sections, wherein the straight line where the basic diameter is located divides the arc of the reverse thrust side surface into a third profile line and a fourth profile line connected to the front and rear sections, wherein the first profile line satisfies the equation x=0.00043y 2 -0.00129y-D0 / 2, the x-axis in the equation is the straight line where the basic diameter of the piston is located, the y-axis is the radial center line of the piston perpendicular to the basic diameter of the piston, the value range of y in the equation is 3≤y≤21, the second profile line and the fourth profile line are symmetrical about the y-axis, and the first profile line and the third profile line are asymmetrical about the y-axis.

[0007] As a further solution of the present invention: when the points on the first mold line and the points on the third mold line are at the same distance from the x-axis, the distance L1 between the points on the first mold line and the y-axis is smaller than the distance between the points on the third mold line and the y-axis.

[0008] As a further solution of the present invention: the value range of D0 is 73mm≤D0≤86mm.

[0009] An engine comprises the above-mentioned asymmetric piston with skirt.

[0010] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention has a novel structure, and according to the different amounts of thermal expansion of the thrust side and the reverse thrust side of the piston skirt during the operation of the engine, the present invention designs the arc formed by the thrust side and the reverse thrust side of the piston skirt into an asymmetric form, thereby increasing the reduction of the piston thrust side skirt, so that during the operation of the engine, the reduction of the thrust side of the piston skirt is offset by the expansion after heating, so that the gap between the thrust side of the piston skirt and the cylinder barrel can be within a reasonable range, reducing the possibility of contact between the thrust side of the piston skirt and the cylinder barrel, thereby reducing the friction generated by the contact between the piston and the cylinder barrel and the combustion load of the engine. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a front view of a piston with an asymmetric skirt;

[0012] Figure 2 A schematic diagram of a partial top view cross section of a piston with an asymmetric skirt;

[0013] Figure 3 The distribution diagram of the skirt surface pressure test of an asymmetric skirt piston with a D0 of 73 mm;

[0014] Figure 4 It is a distribution diagram of skirt surface pressure test of a skirt symmetrical piston with DO of 73 mm in the prior art;

[0015] Figure 5 The distribution diagram of the skirt surface pressure test of an asymmetric skirt piston with a D0 of 77 mm;

[0016] Figure 6 It is a distribution diagram of skirt surface pressure test of a skirt symmetrical piston with DO of 77 mm in the prior art;

[0017] Figure 7 The distribution diagram of the skirt surface pressure test of an asymmetric skirt piston with a D0 of 82 mm;

[0018] Figure 8 It is a distribution diagram of skirt surface pressure test of a skirt symmetrical piston with DO of 82 mm in the prior art;

[0019] Fig. 9 The distribution diagram of the skirt surface pressure test of an asymmetric skirt piston with a D0 of 86 mm;

[0020] Fig.10 It is a distribution diagram of skirt surface pressure test of a skirt symmetrical piston with DO of 86 mm in the prior art;

[0021] In the figure: 10-piston, 20-thrust side, 21-first profile, 22-second profile, 30-reverse thrust side, 31-third profile, 32-fourth profile. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only 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.

[0023] See also Figure 1 In an embodiment of the present invention, a skirt asymmetric piston and an engine include a piston skirt, wherein the side surface of the piston skirt is evenly divided into a thrust side surface 20 and a reverse thrust side surface 30, the arc formed by the thrust side surface of the piston skirt has a highest point, and similarly, the arc formed by the non-thrust side surface of the piston skirt also has a highest point, the horizontal distance between the highest point of the thrust side arc line and the highest point of the reverse thrust side arc line is the basic diameter D0 of the piston, the straight line where the basic diameter of the piston is located divides the thrust side arc line into a first profile line 21 and a second profile line 22 connected to each other in front and back sections, and the straight line where the basic diameter is located divides the reverse thrust side arc line into a third profile line 31 and a fourth profile line 32 connected to each other in front and back sections.

[0024] The second profile 22 and the fourth profile 32 are symmetrical about the radial center line of the piston perpendicular to the basic diameter of the piston, and the first profile 21 and the third profile 31 are asymmetrical about the radial center line of the piston perpendicular to the basic diameter of the piston, which is specifically manifested in that when the points on the first profile 21 and the points on the third profile 31 are at the same distance from the x-axis, the distance L1 between the points on the first profile and the y-axis is smaller than the distance between the points on the third profile and the y-axis.

[0025] The first profile satisfies the equation x=0.00043y 2 -0.00129y-D0 / 2, the x-axis in the equation is the straight line where the piston basic diameter is located, the y-axis is the radial center line of the piston perpendicular to the piston basic diameter, the value range of y in the equation is 3mm≤y≤21mm, and D0 can be but is not limited to 73mm, 77mm, 82mm, 86mm.

[0026] The thrust side and reverse thrust side profiles of the above-mentioned piston skirt are asymmetrical, and the curvature of the arc formed by the thrust side is smaller than the curvature of the arc formed by the reverse thrust side, which is mainly manifested in that when the points on the first profile 21 and the points on the third profile 31 are at the same distance from the x-axis, the distance L1 between the points on the first profile and the y-axis is smaller than the distance between the points on the third profile and the y-axis. During the operation of the engine, the diameter of the piston skirt increases due to thermal expansion, while the expansion amounts of the thrust side and the reverse thrust side of the piston skirt due to thermal expansion are different, the thrust side expanding by thermal expansion is larger, and the reverse thrust side expanding by thermal expansion is smaller. Therefore, during the operation of the engine, the thrust side has a gap too small with the inner wall of the cylinder due to the large expansion, which will cause strong contact between the thrust side of the piston skirt and the inner wall of the cylinder, affecting the normal operation of the engine. Based on the above-mentioned characteristics of the piston skirt, the present invention arranges the thrust side and the reverse thrust side of the piston skirt in an asymmetric form, so that the curvature of the arc formed by the thrust side of the piston skirt is smaller than the curvature of the arc formed by the reverse thrust side of the piston. When the engine is running, the portion of the thrust side of the piston skirt that is reduced compared to the reverse thrust side can offset the expansion amount of the thrust side of the piston skirt due to thermal expansion, so that a reasonable gap is maintained between the thrust side and the inner wall of the cylinder, reducing the possibility of strong contact between the thrust side and the inner wall of the cylinder.

[0027] In order to verify the above theoretical derivation, this embodiment conducts an experimental verification on the above-mentioned asymmetric piston with skirt:

[0028] When D0=73mm, the relevant parameters in the verification experiment are: engine explosion pressure: 11MPa, engine power: 103KW; engine displacement: 1.5L; compression ratio: 10; cylinder diameter: 73mm; stroke: 86mm; speed: 4000rpm; pin hole diameter: 19mm; pin length: 50mm; pin connection method: semi-floating; pin hole eccentricity: 0.6mm; connecting rod end width: 19mm; connecting rod center distance: 130mm; crankshaft radius: 69.5mm; crankshaft eccentricity: 0.6mm.

[0029] When D0=73 mm, the first profile satisfies the equation x=0.00043y 2 -0.00129y-38.5, and 3mm≤y≤21mm, the shape of the first profile of the piston skirt is determined, and after the shape of the piston skirt is determined, 3D models are designed for the asymmetric piston with skirt and the symmetric piston with skirt in the prior art, and the skirt surface pressure tests are performed on the asymmetric piston with skirt and the symmetric piston with skirt, respectively, to obtain Figure 3 and Figure 4The surface pressure test distribution diagram, in which the surface pressure values ​​decrease from the inside to the outside, and the surface pressure values ​​from the inside to the outside are 45-50, 40-45, 35-40, 30-35, 25-30, 20-25, 15-20, 10-15, 5-10, and 0-5, where the unit is: MPa.

[0030] From the final experimental data diagram, it can be seen that when the piston skirt adopts an asymmetric form and the piston basic diameter D0 = 73mm, and the first profile line of the piston skirt thrust side meets x = 0.00043y 2 -0.00129y-D0 / 2, 3mm≤y≤21mm, the contact surface pressure on the asymmetric piston with skirt as a whole is significantly smaller than the contact surface pressure on the symmetric piston with skirt as a whole, which is mainly manifested in that the skirt area of ​​the asymmetric piston with skirt within the contact surface pressure range of 40-50MPa is smaller than the skirt area of ​​the symmetric piston with skirt within the contact surface pressure range of 40-50MPa. By setting the piston skirt to an asymmetric form, the contact pressure between the piston thrust side skirt and the cylinder barrel is reduced, thereby reducing the friction between the piston and the cylinder barrel, and reducing the combustion load of the engine.

[0031] When D0=77mm, the relevant parameters in the verification experiment are: engine explosion pressure: 11MPa; engine power: 115KW; engine displacement: 1.5L; compression ratio: 11.1; cylinder diameter: 77mm; stroke: 79.82mm; speed: 4000rpm; pin hole diameter: 20mm; pin length: 51mm; pin connection method: semi-floating; pin hole eccentricity: 0.5mm; connecting rod end width: 19.5mm; connecting rod center distance: 142.15mm; crankshaft radius: 76.9mm; crankshaft eccentricity: 8mm.

[0032] When D0=77 mm, the first profile satisfies the equation x=0.00043y 2 -0.00129y-41, and 3≤y≤21, the shape of the first profile of the piston skirt is determined, and after the shape of the piston skirt is determined, 3D models are designed for the asymmetric piston with skirt and the symmetric piston with skirt in the prior art, and the skirt surface pressure tests are performed on the asymmetric piston with skirt and the symmetric piston with skirt, respectively, to obtain Figure 5 and Figure 6 The surface pressure test distribution diagram, in which the surface pressure values ​​decrease from the inside to the outside, and the surface pressure values ​​from the inside to the outside are 45-50, 40-45, 35-40, 30-35, 25-30, 20-25, 15-20, 10-15, 5-10, and 0-5, where the unit is: MPa.

[0033] From the final experimental data diagram, it can be seen that when the piston skirt adopts an asymmetric form and the piston basic diameter D0 = 77mm, and the first profile line of the piston skirt thrust side meets x = 0.00043y 2 -0.00129y-D0 / 2, 3mm≤y≤21mm, the contact surface pressure on the asymmetric piston of the skirt as a whole is significantly smaller than the contact surface pressure on the symmetric piston of the skirt as a whole, which is mainly manifested in that the skirt area of ​​the asymmetric piston of the skirt within the contact surface pressure range of 45-50MPa is smaller than the skirt area of ​​the symmetric piston of the skirt within the contact surface pressure range of 45-50MPa. By setting the piston skirt to an asymmetric form, the contact pressure between the piston thrust side skirt and the cylinder barrel is reduced, thereby reducing the friction between the piston and the cylinder barrel, and reducing the combustion load of the engine.

[0034] When D0=82mm, the relevant parameters in the verification experiment are: engine explosion pressure: 11MPa; engine power: 140KW; engine displacement: 2.0L; compression ratio: 11.3; cylinder diameter: 82mm; stroke: 93mm; speed: 4800rpm; pin hole diameter: 21mm; pin length: 53mm; pin connection method: semi-floating; pin hole eccentricity: 0.5mm; connecting rod end width: 16.8mm; connecting rod center distance: 143.8mm; crankshaft radius: 75mm; crankshaft eccentricity: 6mm.

[0035] When D0=82 mm, the first profile satisfies the equation x=0.00043y 2 -0.00129y-43, and 3≤y≤21, the shape of the first profile of the piston skirt is determined, and after the shape of the piston skirt is determined, 3D models are designed for the asymmetric piston with skirt and the symmetric piston with skirt in the prior art, and the skirt surface pressure tests are performed on the asymmetric piston with skirt and the symmetric piston with skirt, respectively, to obtain Figure 7 and Figure 8 The surface pressure test distribution diagram, in which the surface pressure values ​​decrease from the inside to the outside, and the surface pressure values ​​from the inside to the outside are 45-50, 40-45, 35-40, 30-35, 25-30, 20-25, 15-20, 10-15, 5-10, and 0-5, where the unit is: MPa.

[0036] From the final experimental data diagram, it can be seen that when the piston skirt adopts an asymmetric form and the piston basic diameter D0 = 82mm, and the first profile line of the piston skirt thrust side meets x = 0.00043y 2-0.00129y-D0 / 2, 3mm≤y≤21mm, the contact surface pressure on the asymmetric piston of the skirt as a whole is significantly smaller than the contact surface pressure on the symmetric piston of the skirt as a whole, which is mainly manifested in that the skirt area of ​​the asymmetric piston of the skirt within the contact surface pressure range of 35-50MPa is smaller than the skirt area of ​​the symmetric piston of the skirt within the contact surface pressure range of 35-50MPa. By setting the piston skirt to an asymmetric form, the contact pressure between the piston thrust side skirt and the cylinder barrel is reduced, thereby reducing the friction between the piston and the cylinder barrel, and reducing the combustion load of the engine.

[0037] When D0=86mm, the relevant parameters in the verification experiment are: engine explosion pressure: 12MPa; engine power: 170KW; engine displacement: 2.0L; compression ratio: 10; cylinder diameter: 86mm; stroke: 84.7mm; speed: 4000rpm; pin hole diameter: 22mm; pin length: 62mm; pin connection method: semi-floating; pin hole eccentricity: 0.6mm; connecting rod end width: 23mm; connecting rod center distance: 141.2mm; crankshaft radius: 76mm; crankshaft eccentricity: 9mm.

[0038] When D0=86 mm, the first profile satisfies the equation x=-0.00043y 2 -0.00129y-36.5, and 3≤y≤21, the shape of the first profile of the piston skirt is determined, and after the shape of the piston skirt is determined, 3D models are designed for the asymmetric piston with skirt and the symmetric piston with skirt in the prior art, and the skirt surface pressure tests are performed on the asymmetric piston with skirt and the symmetric piston with skirt, respectively, to obtain Figure 3 and Figure 4 The surface pressure test distribution diagram, in which the surface pressure values ​​decrease from the inside to the outside, and the surface pressure values ​​from the inside to the outside are 45-50, 40-45, 35-40, 30-35, 25-30, 20-25, 15-20, 10-15, 5-10, and 0-5, where the unit is: MPa.

[0039] From the final experimental data diagram, it can be concluded that when the piston skirt adopts an asymmetric form and the piston basic diameter D0 = 73mm, and the first profile line of the piston skirt thrust side meets x = 0.00043y 2-0.00129y-D0 / 2, 3mm≤y≤21mm, the contact surface pressure on the asymmetric piston of the skirt as a whole is significantly smaller than the contact surface pressure on the symmetric piston of the skirt as a whole, which is mainly manifested in that the skirt area of ​​the asymmetric piston of the skirt within the contact surface pressure range of 45-50MPa is smaller than the skirt area of ​​the symmetric piston of the skirt within the contact surface pressure range of 45-50MPa. By setting the piston skirt to an asymmetric form, the contact pressure between the piston thrust side skirt and the cylinder barrel is reduced, thereby reducing the friction between the piston and the cylinder barrel, and reducing the combustion load of the engine.

[0040] During the operation of the engine, the expansion amount of the thrust side and the reverse thrust side of the piston skirt due to heat is different. The expansion amount of the thrust side due to heat is larger, and the expansion amount of the reverse thrust side due to heat is smaller. In view of the above characteristics, the present invention sets the first profile of the thrust side of the piston skirt to satisfy the equation x=0.00043y 2 -0.00129y-D0 / 2 and 3mm≤y≤21mm, so that the curvature of the arc formed by the thrust side of the piston skirt is smaller than the curvature of the arc formed by the reverse thrust side of the piston, and the portion of the thrust side of the piston skirt that is reduced compared to the reverse thrust side can offset the expansion of the thrust side of the piston skirt due to heat, so that a reasonable gap is maintained between the thrust side and the inner wall of the cylinder. The above four groups of experiments can verify that: when the basic diameter D0 is in the range of 73-86mm, the piston skirt in the present invention can effectively reduce the contact surface pressure on the piston skirt through the above arrangement, which further proves that the piston skirt can reduce the contact between the piston skirt and the cylinder through the above arrangement, thereby reducing the friction generated between the piston and the cylinder and the combustion load of the engine.

[0041] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0042] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A piston with an asymmetric skirt, comprising a piston skirt, wherein the side surface of the piston skirt is evenly divided into a thrust side surface (20) and a reverse thrust side surface (30), characterized in that: The horizontal distance between the highest point of the arc formed by the thrust side and the highest point of the arc formed by the reverse thrust side in the piston skirt is the basic diameter D0 of the piston (10). The straight line where the basic diameter is located divides the thrust side arc into a first profile line (21) and a second profile line (22) connected to each other in front and back. The straight line where the basic diameter is located divides the reverse thrust side arc into a third profile line (31) and a fourth profile line (32) connected to each other in front and back. The first profile line satisfies the equation x=0.00043y 2 -0.00129y-D0 / 2, the x-axis in the equation is the straight line where the basic diameter of the piston is located, the y-axis in the equation is the radial center line of the piston perpendicular to the basic diameter of the piston, the value range of the y-axis in the equation is 3mm≤y≤21mm, the second type line and the fourth type line are symmetrical about the y-axis, and the first type line and the third type line are asymmetrical about the y-axis.

2. A skirt asymmetric piston according to claim 1, characterized in that: When the points on the first profile (21) and the points on the third profile (31) are at the same distance from the x-axis, the distance L1 between the points on the first profile and the y-axis is smaller than the distance between the points on the third profile and the y-axis.

3. The asymmetric skirt piston according to claim 1, characterized in that: The value range of D0 is 73mm≤D0≤86mm.

4. An engine, characterized in that: A piston with an asymmetric skirt comprising any one of claims 1-3.

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