Piston design features that minimize periodic second land pressure variations

Abstract

The piston includes an annular body including a crown defining a longitudinal axis, a radial direction perpendicular to the longitudinal axis, and a circumferential direction. The crown includes a top extrusion surface and a circumferential annular wall extending axially downward from the top extrusion surface, and a skirt. A first piston ring receiving groove is spaced apart from the top extrusion surface, upper and lower groove ridges extend from the first piston ring receiving groove, and a bottom blend connects the lower groove ridge to the first piston ring receiving groove.

Description

Technical Field

[0001] This invention generally relates to pistons used in internal combustion engines, which have piston ring grooves and groove ridges between these grooves. More specifically, this invention relates to a piston having design features that minimize pressure variations in the second groove ridge. Background Technology

[0002] Internal combustion engines are commonly used in various industries to power machinery and equipment. Examples of industries using such machinery and equipment include shipbuilding, earthmoving, construction, mining, locomotives, and agriculture. In certain markets and market segments, there is a demand for cleaner, more efficient, and less maintenance-intensive internal combustion engines.

[0003] More specifically, piston rings need frequent replacement because engine problems can occur when they wear out. In compression-ignition engines, this can lead to load-induced rapid combustion (LIRC, a phenomenon similar to knocking in gas turbine engines), as well as higher emissions from fuel combustion, higher fuel consumption, and increased piston deposits.

[0004] CN104421037A discloses a piston having grooves for removing material (see...). Figure 2 This creates gaps that can trap debris and other contaminants over time.

[0005] It can be seen that the piston design of CN104421037A does not adequately address issues such as reducing maintenance. Summary of the Invention

[0006] A piston, configured to reciprocate within a bore of an engine according to an embodiment of the invention, is provided. The piston may include an annular body comprising a crown defining a longitudinal axis, a radial direction perpendicular to the longitudinal axis, and a circumferential direction. The annular body may include a top pressing surface of the crown, a circumferential annular wall extending axially downward from the top pressing surface, and a skirt extending axially downward from the circumferential annular wall. The circumferential annular wall may define a first groove and a second groove, the first groove being axially spaced from the top pressing surface to form a first ridge, and the second groove being axially spaced from the first groove to form a second ridge. A bottom blending portion extends axially and radially from the second groove.

[0007] A piston, configured to reciprocate within a bore of an engine according to another embodiment of the invention, is provided. The piston may include an annular body comprising a crown defining a longitudinal axis, a radial direction perpendicular to the longitudinal axis, and a circumferential direction. The annular body may include a top pressing surface of the crown, a circumferential annular wall extending axially downward from the top pressing surface, and a skirt extending axially downward from the circumferential annular wall. The circumferential annular wall defines a first groove and a second groove, the first groove being axially spaced from the top pressing surface to form a first ridge, and the second groove being axially spaced from the first groove to form a second ridge. A first blending portion extends axially and radially from the second groove.

[0008] A piston, configured to reciprocate within a bore of an engine according to another embodiment of the invention, is provided. The piston may include an annular body comprising a crown defining a longitudinal axis, a radial direction perpendicular to the longitudinal axis, and a circumferential direction. The annular body may further include a top pressing surface of the crown, a circumferential annular wall extending axially downward from the top pressing surface, and a skirt extending axially downward from the circumferential annular wall. The circumferential annular wall may define a first piston ring receiving groove spaced apart from the top pressing surface, an upper groove ridge extending from the first piston ring receiving groove, and a lower groove ridge extending from the first piston ring receiving groove. A bottom blending portion may connect the lower groove ridge to the first piston ring receiving groove. Attached Figure Description

[0009] Figure 1 This is a perspective view of an internal combustion engine with a piston that can be used according to various embodiments of the present invention.

[0010] Figure 2 yes Figure 1 A cross-sectional side view of an internal combustion engine shows a piston according to an embodiment of the invention, which is arranged in a cylinder bore for reciprocating motion therein.

[0011] Figure 3 According to embodiments of the present invention, it is possible to... Figure 1 and 2 A front view of a piston used in an engine, including chamfered grooves. A skirt on the thrust or counter-thrust side of the piston is also shown.

[0012] Figure 4 yes Figure 3 An enlarged front sectional view of the piston taken along line 4-4 shows the geometry of the chamfered groove more clearly.

[0013] Figure 5 It is possible Figure 1 and Figure 2 A front view of a piston used in an engine, the piston including a chamfered groove according to another embodiment of the invention. A skirt on the thrust or counter-thrust side of the piston is also shown.

[0014] Figure 6 yes Figure 5 An enlarged front sectional view of the piston taken along line 6-6 shows the geometry of the double chamfered groove more clearly.

[0015] Figure 7 It is a graph showing the reduction of pressure in the top groove and the second groove ridge according to various embodiments of the present invention.

[0016] Figure 8 This is a graph illustrating the ring lift of various embodiments of the present invention and the comparable performance of other existing designs. Detailed Implementation

[0017] Reference will now be made in detail to embodiments of the invention, examples of which are illustrated in the accompanying drawings. Throughout the drawings, the same reference numerals are used wherever possible to denote the same or similar parts. In some cases, reference numerals will be indicated in this specification, and the drawings will display reference numerals followed by letters such as 100a, 100b, or principal indicators such as 100', 100", etc. It should be understood that the use of letters or principal indicators immediately after the reference numerals indicates that these features have similar shapes and functions similarly to those typically seen when the geometry is mirrored about a plane of symmetry. For ease of explanation in this specification, letters or principal indicators are generally not included herein but may be shown in the drawings to indicate repetition of features discussed in this written specification.

[0018] Various embodiments of pistons that can be used in internal combustion engines according to various embodiments of the invention will now be described. More specifically, removing the corner material at the bottom and / or top of the groove can reduce the variation in the effective clearance area when the piston is on the thrust or counter-thrust side, thereby allowing for a more consistent second groove ridge pressure at the critical time of the engine cycle.

[0019] For example, Figure 1 The internal combustion engine 100 shown may employ various embodiments of pistons constructed according to the principles described herein. The engine 100 may include an engine block 102 and a cylinder head 104, in which a piston (not shown) reciprocates, and the cylinder head 104 may contain various engine components for introducing fluid into orifices / combustion chambers located in the engine block 102.

[0020] Turn Figure 2A portion of an engine 100 is shown, including a combustion chamber 106, which may have a generally cylindrical shape defined within a cylinder bore 108 formed within a crankcase or engine block 102 of the engine 100. The combustion chamber 106 is also defined at one end by a flame plate surface 110 of a cylinder head 104 and at the other end by a crown 202 of a piston 200 reciprocatingly disposed within the bore 108 and connected to a connecting rod 124, which in turn is connected to a crankshaft (not shown). A fuel injector 112 is mounted in the cylinder head 104. The injector 112 has a tip 114 protruding through the flame plate surface 110 into the combustion chamber 106, allowing it to inject fuel directly into the combustion chamber 106.

[0021] During operation of engine 100, air is allowed to enter combustion chamber 100 via intake passage 115 when one or more intake valves 117 (one shown) open during the intake stroke. In a known configuration, high-pressure fuel is allowed to flow through nozzle openings (hereinafter referred to as orifices) in tip 114 to form a fuel jet entering combustion chamber 106. Each nozzle opening produces a fuel jet 118 that is generally dispersed to produce a predetermined fuel / air mixture that is automatically ignited and combusted in a compression-ignition engine. Fuel jet 118 may be supplied from the injector at an angle β between 110 and 150 degrees, but other angles may also be used. After combustion, exhaust gas is discharged from combustion chamber through exhaust passage 120 when one or more exhaust valves 122 (one shown) open during the exhaust stroke.

[0022] The uniformity and degree of fuel / air mixing in the combustion cylinder are related to combustion efficiency and the amount and type of combustion byproducts formed. For example, a fuel-rich mixture that exists locally in the combustion chamber 106 due to insufficient mixing during combustion can lead to higher soot emissions and lower combustion efficiency.

[0023] See Figures 3 to 6 Now we will discuss pistons 200 and 300, which are configured for use in engine 100 (e.g. Figure 2 The piston reciprocates within the hole 108, and the piston is generally constructed according to the principles of the invention.

[0024] from Figure 3 and Figure 5 Initially, pistons 200 and 300 may include annular bodies 202 and 302 (e.g., cylindrical, conical, etc.), the annular bodies including crowns 204 and 304 defining longitudinal axes 206 and 306, radial directions 208 and 308 perpendicular to the longitudinal axes 206 and 306, and circumferential directions 210 and 310.

[0025] Crowns 204, 304 may include top extrusion surfaces 212, 312 and circumferential annular walls 214, 314 extending axially downward from the top extrusion surfaces 212, 312 (see...). Figure 4 and Figure 6 ), and skirts 216 and 316 extending axially downward from the circumferential annular walls 214 and 314 (see Figure 3 and Figure 5 In use, the skirt typically faces the thrust side or the reverse thrust side of the cylinder bore.

[0026] To prevent them from being blown out during the combustion cycle, the crowns 204, 304 include first piston ring receiving grooves 218, 318, which are axially spaced from the top compression surfaces 212, 312. It should be understood that during operation, the piston rings will be present in these grooves, but they are not shown in the drawings for clarity. Figure 4 and Figure 6 As shown, the upper groove ridges 220 and 320 extend axially upward from the first piston ring receiving grooves 218 and 318, and the lower groove ridges 222 and 322 extend axially downward from the first piston ring receiving grooves 218 and 318.

[0027] To reduce groove ridge pressure, etc., at least one bottom blending portion 224, 324 is provided to connect the lower groove ridge 222 to the first piston ring receiving grooves 218, 318 (which can be any transition surface, such as a conical surface, a constant blending portion, a variable blending portion known in computer-aided drawing software, an arcuate surface, etc.). More specifically, the bottom blending portion 224, 324 can take the form of a bottom chamfer 224a, 324a (i.e., it is in the plane containing the radial direction and the longitudinal axis (e.g., Figure 4 and Figure 6 (The cross-sectional plane appears flat, but in three dimensions it will be at least partially tapered). Similarly, the top blending portion 326 can connect the upper groove ridge 320 to the first piston ring receiving groove 318 (see...). Figure 6 ).

[0028] See Figure 4 and 6 It is understood that the circumferential annular walls 214, 314 also define second piston ring receiving grooves 228, 328, which are axially arranged between the top extrusion surfaces 212, 312 and the first piston ring receiving grooves 218, 318. Similarly, the circumferential annular walls 214, 314 may further define oil grooves 230, 330, which are axially arranged below the first piston ring receiving grooves 218, 318. These auxiliary grooves may not exist in other embodiments of the invention.

[0029] When present, the second piston ring receiving grooves 228, 328 can be axially spaced from the top extrusion surfaces 212, 312 by a first axial distance 232, 332, which can be in the range of 3.0 mm to 12.0 mm, forming a first cylindrical groove ridge surface 234, 334, which defines a first diameter 236, 336 (see...). Figure 3 and Figure 5 The first diameters 236 and 336 can be in the range of 168.0 mm to 170.0 mm in some embodiments. Furthermore, in some embodiments, the second piston ring receiving grooves 228 and 328 can define an axial width 238 and 338 of the second piston ring receiving groove, which can be in the range of 2.0 mm to 5.0 mm (see...). Figure 4 and Figure 6 And the minimum diameter of the second piston ring receiving groove, 240 or 340, can be in the range of 154.0 mm to 161.0 mm (see...). Figure 3 and Figure 5 ).

[0030] See Figure 4 and Figure 6 The first piston ring receiving grooves 218 and 318 can be axially spaced from the second piston ring receiving grooves 228 and 328 by a second axial distance 242 and 342, respectively. This second axial distance 242 and 342 can be in the range of 3.0 mm to 12.0 mm, thereby forming a second cylindrical groove ridge surface 244 and 344. In some embodiments, a second diameter 246 and 346 are defined (see...). Figure 3 and Figure 5 The second diameter can be in the range of 168.0 mm to 170.0 mm. Furthermore, in some embodiments, the first piston ring receiving grooves 218, 318 can define the axial widths of the first piston ring receiving grooves 248, 348 (see...). Figure 4 and Figure 6 The diameter of the first piston ring receiving groove can be in the range of 2.0mm to 5.0mm, and the minimum diameter of the groove is 250mm or 350mm, which can be in the range of 154.0mm to 161.0mm (e.g.). Figure 3 and 5 (As shown in the best example).

[0031] In addition, such as Figure 4 and Figure 6As best shown, oil grooves 230 and 330 can be axially spaced from the first piston ring receiving grooves 218 and 318 by a third axial distance 252 and 352, respectively. This third axial distance 252 and 352 can be in the range of 3.0 mm to 12.0 mm, forming a third cylindrical groove ridge surface 254 and 354. This third cylindrical groove ridge surface 254 and 354 defines a third diameter 256 and 356, which in some embodiments can be in the range of 168.0 mm to 170.0 mm (see [reference needed]). Figure 3 and Figure 5 Furthermore, in some embodiments, oil grooves 230 and 330 may define an axial width of 258 and 358 and a minimum diameter of 260 and 360, respectively, with the axial width of 258 and 358 ranging from 2.0 mm to 5.0 mm (see [link to relevant documentation]). Figure 4 and 6 The minimum diameter of the oil tank (260mm and 360mm) is in the range of 154.0mm to 162.0mm (see...). Figure 3 and Figure 5 ).

[0032] In addition, Figure 3 and Figure 5 In the middle, the circumferential annular walls 214, 314 further define the bottom cylindrical surfaces 262, 362, which are axially arranged below the oil grooves 230, 330, defining the fourth diameters 264, 364. In some embodiments, the fourth diameters 264, 364 can be in the range of 165.0 mm to 170.0 mm.

[0033] It is conceivable that these different features may be configured and sized differently from those described only in other embodiments of the invention.

[0034] Now refer to Figures 3 to 6 The discussion focuses on pistons 200 and 300, which can be provided as alternative components for specific applications.

[0035] exist Figure 4 and Figure 6 In the design, circumferential annular walls 214 and 314 define first grooves 228a and 328a and second grooves 218a and 318a. The first grooves 228a and 328a are axially spaced from the top extrusion surfaces 212 and 312, forming first ridges 268 and 368. The second grooves 218a and 318a are axially spaced from the first grooves 228a and 328a, forming second ridges 220a and 320a. Furthermore, at least bottom chamfers 224a and 324a extend axially and radially from the second grooves 218a and 318a.

[0036] Similarly, Figure 3 and Figure 5As shown, the connecting rod attachment portions 270 and 370 can extend axially downward from the crown portions 204 and 304. The connecting rod attachment portions 270 and 370 typically have holes for receiving pins passing through the hole and through the connecting rod. This connection is not shown in the figures, but should be understood to exist. Figure 2 In operation.

[0037] exist Figure 4 and Figure 6 In the middle, the crown portions 204 and 304 may further define the third grooves 230a and 330a, which are axially spaced from the second grooves 218a and 318a, forming the third groove ridges 222a and 322a. The bottom chamfers 224a and 324a extend radially and axially from the third groove ridges 222a and 322a to the second grooves 218a and 318a.

[0038] exist Figure 3 and Figure 5 In this configuration, skirt portions 216 and 316 may define circumferential ranges 216a and 316a, and bottom chamfers 224a and 324a may be axially arranged above skirt portions 216 and 316. In this case, bottom chamfers 224a and 324a may extend circumferentially at least as much as the circumferential ranges 216a and 316a of the skirt portions.

[0039] exist Figure 3 In the middle, the bottom chamfer 224a extends 360 degrees circumferentially around the longitudinal axis 206. Figure 5 In the piston 300, the bottom chamfer 324a extends circumferentially around the longitudinal axis 306 by an angle of less than 180 degrees. It should be understood that one or more chamfers may be present on the other side (blind side) of the piston 300. In this case, the piston may define two planes of symmetry (one of which could be...). Figure 4 and Figure 6 The two symmetrical planes (the cross-sectional planes) contain a radial direction and a longitudinal axis and are perpendicular to each other. This may not be the case in other embodiments of the invention.

[0040] like Figure 4 and Figure 6 As shown, the cross-sectional plane includes radial directions 208, 308 and longitudinal axes 206, 306. Furthermore, the bottom chamfers 224a, 324a define angles 272, 372 with the radial directions in the plane, ranging from 40 to 50 degrees (e.g., 45 degrees). In this case, the bottom chamfers 206, 306 (or the top chamfer 326a) define radial distances 280, 380 (i.e., distances measured in the radial direction) ranging from 0.25 mm to 0.75 mm (e.g., 0.5 mm) in the plane. In other embodiments of the invention, other configurations and dimensional ranges are possible. Figure 6In this case, the top chamfer 326a has a geometry that is mirror or symmetrical with respect to the geometry of the plane 374 in the groove perpendicular to the longitudinal axis 306 and the bottom chamfers 206, 306. This may not be the case in other embodiments of the invention.

[0041] Another embodiment of pistons 200 and 300, which can be provided as alternative components, may have the following features.

[0042] exist Figure 4 and Figure 6 In the design, circumferential annular walls 214 and 314 define first grooves 228a and 328a and second grooves 218a and 318a, respectively. The first grooves 228a and 328a are axially spaced from the top extrusion surfaces 212 and 312 to form first ridges 268 and 368, respectively. The second grooves 218a and 318a are axially spaced from the first grooves 228a and 328a to form second ridges 220a and 220b, respectively. At least a first chamfer (e.g., 224a, 324a, 326a) extends axially and radially from the second grooves 218a and 318a.

[0043] exist Figure 6 In the middle, there are a first chamfer and a second chamfer (e.g., bottom chamfer 324a, top chamfer 326a). Both can extend axially and radially from the second grooves 218a, 318a, and both can extend around the longitudinal axis 306 with the same circumferential range 327, ranging from 110 degrees to 130 degrees (e.g., 120 degrees).

[0044] More specifically, such as in Figure 5 As best seen, the top chamfer 326a and the bottom chamfer 324a are axially arranged above the skirt 316, and in a plane including the radial and longitudinal axes (e.g., Figure 6 The cross-sectional plane has the largest dimension, and the dimension decreases as it approaches the end of the circumferential range 327 376 (see...). Figure 5 This can be modeled using computer-aided drafting software via a variable blending function. Other configurations are possible in other embodiments of the invention.

[0045] As used herein, “arch” includes any shape that is not straight or flat, including radii, ellipses, polynomials, splines, etc. As used herein, the term “blend” can include any suitable geometry, including chamfers (having a flat or conical shape), radii, or other arched curve segments that function as chamfers to break edges as described herein. In any embodiment discussed herein, a chamfer may be used instead of a blend, and vice versa.

[0046] The configurations and size ranges of any of the embodiments discussed herein may vary depending on the application.

[0047] The piston can be made of steel, cast aluminum alloy, forged aluminum alloy, or other suitable durable, corrosion-resistant materials. The geometry of the crown can be formed during casting or forging, and then rough and / or finish machined if necessary. Suitable machining processes can include milling, turning, electrical discharge machining, etc.

[0048] Industrial applicability

[0049] In practice, pistons, piston crowns, and / or engine assemblies using such pistons or piston crowns according to any embodiment described herein may be offered, sold, manufactured, and purchased as needed or desired in the aftermarket or in the context of an OEM (Original Equipment Manufacturer). For example, a crown or piston may be used to retrofit an existing engine already in the field, or may be sold at the first point of sale of the engine or equipment using the engine.

[0050] Figure 7 Instructions for use in engines such as Figures 3 to 6 In the various embodiments of the piston shown, the pressure at the second groove ridge decreases due to the discharge of material from the chamfered groove. Therefore, the LIRC cycle becomes a cycle in which this phenomenon does not occur. More specifically, the vertical axis represents pressure, while the horizontal axis represents crank angle. Peak pressure decreases in the crank angle range of 0 to 100 degrees.

[0051] Similarly, Figure 8 The diagram shows the ring lift at various crank angles throughout the engine cycle (the top shows the top ring lift, while the bottom shows the lower or second ring lift). As can be seen, Figure 8 The diagram shows the top piston ring in the top piston ring groove rising simultaneously with the second piston ring in the second piston ring groove. This can be attributed to the reduced pressure at the second groove ridge of the piston.

[0052] In view of these results, those skilled in the art will anticipate that different embodiments of the piston of the present invention will reduce the likelihood of LIRC (Liquidity-Induced Reduction), as well as the associated higher emissions, higher oil consumption, and increased piston deposits from oil combustion. In other words, various embodiments of the piston of the present invention can reduce these detrimental effects.

[0053] It should be understood that the foregoing description provides examples of the disclosed components and techniques. However, it is conceivable that other implementations of the invention may differ in detail from the foregoing examples. All references to the invention or examples thereof are intended to refer to the specific examples discussed at that point and are not intended to imply any limitation on the scope of the invention in a more general sense. All distinctions and inconsistencies in language regarding certain features are intended to indicate a lack of preference for those features, but not to exclude them entirely from the scope of the invention, unless otherwise specified.

[0054] Unless otherwise stated herein, the descriptions of numerical ranges herein are intended only as a shorthand for individually referring to each individual value falling within the range, and each individual value is incorporated into the specification as if it were described separately herein.

[0055] It will be apparent to those skilled in the art that various modifications and variations can be made to the embodiments of the apparatus and assembly methods discussed herein without departing from the scope or spirit of the invention. Other embodiments of the invention will be apparent to those skilled in the art upon consideration of the description and practice of the various embodiments disclosed herein. For example, some parts of the apparatus may be configured and operated differently from those described herein, and certain steps of any method may be omitted, performed in a different order than specifically mentioned, or in some cases performed simultaneously or in sub-steps. Furthermore, variations or modifications may be made to certain aspects or features of the various embodiments to create further embodiments, and features and aspects of the various embodiments may be added to or replaced in other features or aspects of other embodiments to provide even more further embodiments.

[0056] Therefore, this invention includes all modifications and equivalents of the subject matter described in the appended claims as permitted by applicable law. Furthermore, any combination of the foregoing elements in all possible variations is covered by this invention, unless otherwise stated herein or clearly contradicted by the context.

Claims

1. A piston configured to reciprocate within a bore of an engine, the piston comprising: An annular body includes a crown defining a longitudinal axis, a radial direction perpendicular to the longitudinal axis, and a circumferential direction; the annular body includes: The crown portion has a top extrusion surface, and a circumferential annular wall extending axially downward from the top extrusion surface; and The skirt extends axially downward from the circumferential annular wall; The circumferential annular wall defines a first groove and a second groove, the first groove being axially spaced from the top extrusion surface to form a first ridge, the second groove being axially spaced from the first groove to form a second ridge, a bottom blend portion extending axially and radially from the second groove, and the skirt defining a skirt circumference, the bottom blend portion being axially arranged above the skirt and extending circumferentially at least as much as the skirt circumference and less than 180 degrees.

2. The piston of claim 1, further comprising a connecting rod attachment portion extending from the crown, wherein the crown further defines a third groove axially spaced from the second groove to form a third groove ridge, and the bottom blending portion extends radially and axially from the third groove ridge to the second groove.

3. The piston of claim 1, wherein the annular body defines a plane including the radial direction and the longitudinal axis, and the bottom blend portion is a bottom chamfer, the bottom chamfer defining an angle of 40 to 50 degrees with the radial direction in the plane.

4. The piston of claim 3, wherein the bottom chamfer defines a radial distance of 0.08 mm to 1.5 mm in the plane.

5. A piston configured to reciprocate within a bore of an engine, the piston comprising: An annular body includes a crown defining a longitudinal axis, a radial direction perpendicular to the longitudinal axis, and a circumferential direction; the annular body includes: The crown portion has a top extrusion surface, and a circumferential annular wall extending axially downward from the top extrusion surface; and A skirt portion that extends axially downward from the circumferential annular wall and defines the circumferential range of the skirt portion; The circumferential annular wall defines a first groove and a second groove, the first groove being axially spaced from the top extrusion surface to form a first ridge, the second groove being axially spaced from the first groove to form a second ridge, and the first blending portion extending axially from the second groove and radially around the longitudinal axis for a circumferential range of 110 to 130 degrees.

6. The piston of claim 5, wherein the annular body further defines a second blending portion extending axially and radially from the second groove.

7. The piston of claim 6, wherein the first blending portion is a top chamfer extending axially and radially from the second groove ridge, and the second blending portion is a bottom chamfer extending axially and radially from the third groove ridge.

8. The piston of claim 7, wherein the top chamfer and the bottom chamfer both extend around the longitudinal axis in the same circumferential range, ranging from 110 degrees to 130 degrees, and the top chamfer and the bottom chamfer are axially arranged above the skirt and have a maximum size in a plane including the radial direction and the longitudinal axis, and the size decreases as they approach the end of the circumferential range.

Images