Piston head for combustion cylinder and cooling channel for piston head of combustion cylinder

Abstract

A piston head includes a piston head lower portion and a piston head upper portion coupled to the piston head lower portion. The piston head upper portion includes an end wall, an outer wall, and an inner wall. The end wall includes an outer portion and an inner portion angled relative to the outer portion. The outer wall extends axially away from the end wall in a first direction. The inner wall extends axially away from the end wall in a first direction and is separated from the outer wall such that an outer chamber is defined between the outer wall and the inner wall and an inner chamber is defined within the inner wall. The inner wall defines one or more openings fluidly connecting the inner chamber to the outer chamber. An axis of each of the one or more openings is substantially parallel to the inner portion.

Description

[0001] Cross - reference to related applications

[0002] This application is a PCT application that claims the benefit of Indian Provisional Patent Application No. 202241066203, filed on November 18, 2022, titled "PISTON FOR COMBUSTION CYLINDER", the content of which is incorporated herein by reference in its entirety. This application generally relates to pistons for use in combustion cylinders.

[0003] Field

[0004] This application generally relates to pistons for use in combustion cylinders.

[0005] Background

[0006] Internal combustion engines typically burn a mixture of fuel (e.g., diesel, gasoline, natural gas, etc.) and air in a combustion chamber. The combustion of the air - fuel mixture causes the piston to move, thereby generating power (e.g., for moving a vehicle, powering a device, etc.). The combustion of the air - fuel mixture also increases the temperature of the piston. A fluid such as oil can be provided at the piston to dissipate the heat generated by combustion, thereby cooling the piston.

[0007] Summary

[0008] Various embodiments provide a piston for a combustion cylinder. The piston includes a piston head having a lower piston head portion and an upper piston head portion coupled to the lower piston head portion. The upper piston head portion includes an end wall, an outer wall, and an inner wall. The end wall includes an outer portion and an inner portion angled relative to the outer portion. The outer wall extends axially away from the end wall in a first direction. The inner wall extends axially away from the end wall in the first direction and is separated from the outer wall such that an outer chamber is defined between the outer wall and the inner wall and an inner chamber is defined within the inner wall. The inner wall defines one or more openings fluidly connecting the inner chamber to the outer chamber. The axis of each of the one or more openings is substantially parallel to the inner portion.

[0009] Various other embodiments provide a piston head. The piston head includes a lower piston head portion and an upper piston head portion coupled to the lower piston head portion. The upper piston head portion includes an end wall, an outer wall, and an inner wall. The end wall includes an outer portion and an inner portion angled relative to the outer portion. The outer wall extends axially away from the end wall in a first direction. The inner wall extends axially away from the end wall in the first direction and is separated from the outer wall such that an outer chamber is defined between the outer wall and the inner wall and an inner chamber is defined within the inner wall. The inner wall defines one or more openings fluidly connecting the inner chamber to the outer chamber. The axis of each of the one or more openings is substantially parallel to the inner portion.

[0010] Various other embodiments provide a cooling gallery for a piston head of a combustion cylinder. The cooling gallery includes an end wall that includes an outer portion and an inner portion angled relative to the outer portion. The cooling gallery also includes an outer wall and an inner wall. The outer wall extends axially away from the end wall in a first direction. The inner wall extends axially away from the end wall in the first direction and is separated from the outer wall such that an outer chamber is defined between the outer wall and the inner wall and an inner chamber is defined within the inner wall. The inner wall defines one or more openings that fluidly connect the inner chamber to the outer chamber. The axis of each of the one or more openings is substantially parallel to the inner portion.

[0011] These and other features, along with the organization and manner of their operation, will become apparent from the following detailed description when taken in conjunction with the accompanying drawings, in which like elements have like numerals in several of the drawings described below. Brief Description of the Drawings

[0013] Figure 1 is a cross-sectional view of a combustion chamber assembly according to an exemplary embodiment.

[0014] Figure 2 is Figure 1 another cross-sectional view of the combustion chamber assembly.

[0015] Figure 3 is a perspective view of a piston head that can be used in the combustion chamber assembly for Figure 1 according to an exemplary embodiment.

[0016] Figure 4 is Figure 3 a side cross-sectional view of the piston head.

[0017] Figure 5 is Figure 3 another side cross-sectional view of the piston head.

[0018] Figure 6 is Figure 3 yet another side cross-sectional view of the piston head.

[0019] Figure 7 is Figure 3 a top cross-sectional view of the piston head.

[0020] Figure 8 is a perspective view of the piston head according to an exemplary embodiment of Figure 3 showing a drain plug.

[0021] Figure 9 is Figure 8 a perspective view of the drain plug.

[0022] Figure 10 is according to an exemplary embodiment of Figure 3Perspective view of a piston head, shown with a discharge plug.

[0023] Figure 11 is Figure 10 Perspective view of the discharge plug.

[0024] Figure 12 is Figure 3 Perspective view of the piston head, shown without a discharge plug.

[0025] Detailed description

[0026] The embodiments described herein generally relate to a piston head for a combustion chamber assembly. According to various embodiments, the combustion chamber assembly includes a piston head that is configured to transfer heat from the piston head to a fluid such as oil. The piston head can advantageously improve heat transfer by providing an increased surface area for fluid contact with the piston head.

[0027] Before turning to the drawings, various embodiments of the combustion chamber assembly and its components are described herein. It should be understood that although the individual components are described in detail, these details should be considered only as examples. In addition, the details may include variations described herein. Thus, it should be understood that although individual components may be described with respect to an embodiment, any component may be used in any other embodiment described herein unless otherwise stated.

[0028] The embodiments of the piston used in an internal combustion engine described herein are exposed to high temperatures during operation. To mitigate the temperature, the piston may include cooling channels. When the piston reciprocates along the cylinder bore of the engine, fluid is injected into the cooling channels. The fluid flows along the inner surface of the piston and dissipates heat from the inner surface of the piston. Advantageously, the embodiments described herein always provide sufficient fluid flow to control (e.g., reduce) the piston temperature during operation. The reduced piston temperature can advantageously reduce fluid degradation caused by the high temperature of the internal combustion engine. In addition, the reduced piston temperature can reduce carbon deposition on the surface of the cooling channels caused by high piston temperatures (e.g., piston temperatures greater than 330 °C).

[0029] The embodiments described herein relate to a piston head for a combustion chamber assembly that advantageously improves heat transfer from the combustion chamber to a fluid, such that the operating temperature of the piston is reduced. The reduced operating temperature can improve engine brake thermal efficiency and / or reduce fluid degradation by advantageously reducing oxidation / cooking of the fluid within the cooling channels.

[0030] Reference Figure 1 and Figure 2, which shows a cross-sectional view of a combustion chamber assembly 100 according to an exemplary embodiment. The combustion chamber assembly 100 can be part of an internal combustion engine (such as a spark-ignition engine or a compression-ignition engine). In some embodiments, the combustion chamber assembly 100 is configured to burn fuel, such as gasoline, diesel, propane, hydrogen, etc., to generate power. As shown, the combustion chamber assembly 100 includes a cylinder 102 and a piston 106. It should be understood that the combustion chamber assembly 100 can include more or fewer components than Figure 1 and Figure 2 shown.

[0031] A fluid injection system 120 can be positioned near the combustion chamber assembly 100. The fluid injection system 120 includes a nozzle 122 for supplying fluid. The nozzle 122 can extend towards the piston 106 such that the nozzle 122 supplies fluid to the piston 106. The fluid can include oil used as a coolant and / or lubricant.

[0032] The cylinder 102 includes a cylinder liner 104 that at least partially defines an internal volume. The cylinder 102 is configured to receive an air-fuel mixture within the internal volume. The air-fuel mixture can be burned within the internal volume of the cylinder 102.

[0033] The piston 106 includes a connecting rod 110, a piston pin 112, and a piston head 140. The connecting rod 110 is configured to be coupled to the crankshaft of the internal combustion engine. The piston pin 112 is configured to couple the connecting rod 110 to the piston head 140. The piston head 140 is configured to at least partially define an internal volume such that when the air-fuel mixture burns, the piston head 140 axially translates within the cylinder 102 by the force of combustion. One or more piston rings, shown as a first piston ring 114, a second piston ring 116, and a third piston ring 118, can be disposed between the piston head 140 and the cylinder liner 104. The first piston ring 114, the second piston ring 116, and the third piston ring 118 are expandable rings configured to form a seal between the piston head 140 and the cylinder liner 104. The piston head 140 is described in more detail herein.

[0034] Figure 3 is a perspective view of a piston head 140 that can be used in the Figure 1 combustion chamber assembly 100 according to an exemplary embodiment. In the exemplary embodiment, the piston 106 for the combustion cylinder 100 includes a piston head 140, a connecting rod 110, and a piston pin 112. The piston pin 112 couples the connecting rod 110 to the piston head 140.

[0035] The piston head 140 includes a lower piston head portion 190 and an upper piston head portion 142 coupled to the lower piston head portion 190. The upper piston head portion 142 includes an end wall 144 having an outer portion 146 and an inner portion 148 angled relative to the outer portion 146. The upper piston head portion 142 includes an outer wall 152 axially extending away from the end wall 144 in a first direction. The upper piston head portion 142 includes an inner wall 154 axially extending away from the end wall 142 in the first direction and separated from the outer wall 152 such that an outer chamber 156 is defined between the outer wall 152 and the inner wall 154 and an inner chamber 158 is defined within the inner wall 154. The inner wall 154 defines one or more openings 168 fluidly connecting the inner chamber 158 to the outer chamber 156. The axis of each of the one or more openings 168 is substantially parallel to the inner portion 148.

[0036] The upper piston head portion 142 may be coupled to the lower piston head portion 190 by a welding operation, such as a friction welding operation.

[0037] The outer wall 152 surrounds the perimeter of the end wall 144 and extends axially away from the end wall 144 in the first direction toward the lower piston head portion 190. The end wall 144 includes an outer portion 146 and an inner portion 148. The outer portion 146 extends radially inward from the outer wall 152 toward the inner portion 148 and axially extends toward the lower piston head portion 190 in the first direction such that the outer portion 146 defines a substantially concave shape. The inner portion 148 extends radially inward away from the outer portion 146 toward the center 150 of the end wall 144 and axially extends away from the lower piston head portion 190 in a second direction. The inner portion 148 defines a substantially convex shape such that the apex of the inner portion 148 is located at the center 150. Thus, the inner portion 148 is angled relative to the outer portion 146.

[0038] The outer wall 152 extends toward the lower piston head portion 190 such that when the upper piston head portion 142 is welded to the lower piston head portion 190, the lower piston head portion 190 contacts the outer wall 152. The upper piston head portion 142 includes one or more annular passages shown as a first annular passage 160, a second annular passage 162, and a third annular passage 164. The annular passages 160, 162, 164 extend around the perimeter of the outer wall 152 in a radially outward direction. The annular passages 160, 162, 164 are configured to receive piston rings 114, 116, 118.

[0039] In some embodiments, the lower portion 190 of the piston head includes a piston head body 190 that defines a first inlet port 166 and a first outlet port 167. In some embodiments, the lower portion 190 of the piston head includes a skirt 194 that extends away from the piston head body 190. The skirt 194 defines a pin port 196. The inner cavity 158 is in fluid-providing communication with the pin port 196.

[0040] In some embodiments, the piston 106 includes a piston pin 112 and a connecting rod 110. The piston pin 112 couples the connecting rod 110 to the piston head 140. The piston pin 112 is received by the pin port 196.

[0041] The lower portion 190 of the piston head includes a piston head body 192, a skirt 194, and a pin port 196. The skirt 194 surrounds the perimeter of the piston head body 192 and axially extends away from the piston head body 192 and away from the upper portion 142 of the piston head in a first direction. The skirt 194 at least partially defines the pin port 196. The pin port 196 is configured to receive the piston pin 112 such that when the pin port 196 receives the piston pin 112, the connecting rod 110 is coupled to the piston head 140 via the piston pin 112.

[0042] Now referring Figures 4 - 7 , there is shown Figure 3 various cross-sectional views of the piston head 140. In an exemplary embodiment, the cooling channels of the piston head 140 for the combustion cylinder 100 include an end wall 144 that includes an outer portion 146 and an inner portion 148 that is angled relative to the outer portion 146. The cooling channels include an outer wall 152 that axially extends away from the end wall 144 in a first direction. The cooling channels include an inner wall 154 that axially extends away from the end wall 144 in the first direction and is separated from the outer wall 152 such that an outer cavity 156 is defined between the outer wall 142 and the inner wall 154, and an inner cavity 158 is defined within the inner wall 154. The inner wall 154 defines one or more openings 168 that fluidly connect the inner cavity 158 to the outer cavity 156. The axis of each of the one or more openings 168 is substantially parallel to the inner portion 148.

[0043] As shown, the upper portion 142 of the piston head includes an inner wall 154 disposed radially inwardly from the outer wall 152. As shown, the inner wall 154 has a non-uniform cross-section. More specifically, the width of the inner wall 154 can be non-uniform along the height of the inner wall 154. The non-uniform cross-section achieves improved structural stiffness of the inner wall 154. The outer chamber 156 is at least partially defined by the outer wall 152, the outer portion 146, and the inner wall 154 and extends around the central axis of the piston head 140. The inner chamber 158 is at least partially defined by the inner wall 154 and the inner portion 148 and extends around the central axis of the piston head 140. The outer chamber 156 and the inner chamber 158 together define the internal volume and surface area of the cooling passage. The cooling passage is configured to enable heat transfer from the piston head 140 to a fluid such as oil. In a particular embodiment, the value of the total volume of the cooling passage is equal to a reference value between 251% and 350% of the square of the inner diameter of the cylinder 102. The value of the surface area of the cooling passage is equal to a reference value between 20.5% and 25% of the square of the inner diameter of the cylinder 102 multiplied by the compression height. The compression height is defined as the distance between the centerline of the pin port 196 and the top surface of the piston head 140.

[0044] The piston head 140 includes one or more inlet ports 166 and one or more outlet ports 167. As Figure 7 shown, the piston head body 140 includes two inlet ports 166 and two outlet ports 167. The inlet ports 166 are configured to enable fluid to flow from the fluid injection system 120 to the outer chamber 156 such that the outer chamber is in fluid receiving communication with the fluid injection system 120 via the inlet ports 166. For example, the inlet ports 166 can receive a fluid such as oil from the fluid injection system 120 (e.g., via the nozzle 122) and provide the fluid to the outer chamber 156. The outlet ports 167 are configured to provide fluid from the outer chamber 156 to a downstream device such that the outer chamber 156 is in fluid providing communication with the downstream device via the outlet ports 167. For example, the outlet ports 167 can receive fluid from the outer chamber 156 and provide the fluid to the downstream device.

[0045] In an exemplary embodiment, the piston head 140 includes one or more inlet ports that are configured to receive fluid and provide the fluid to the outer chamber. The piston head 140 includes one or more outlet ports that are configured to receive fluid from the outer chamber and provide the fluid to a downstream device.

[0046] The inner wall 154 includes one or more openings 168. For example, the inner wall 154 may include from six to twelve openings 168. In some embodiments, the one or more openings 168 are equally spaced from each other. In some embodiments, each of the one or more openings 168 has a diameter between 1.5% and 7% of the inner diameter of the cylinder 102.

[0047] The openings 168 fluidly connect the outer chamber 156 and the inner chamber 158. As Figures 4 - 6 shown, the openings 168 are defined through the top of the inner wall 154 proximate the end wall 146. The openings 168 are inclined with respect to the inner wall 156 such that the central axis of the openings 168 is substantially parallel to the inner portion 148. For example, in some embodiments, the openings may be at an angle between 20° and 50° with respect to the horizontal axis. The openings 168 are configured to receive fluid from the outer chamber 156 and provide the fluid to the inner chamber 158 such that the inner chamber 158 is in fluid receiving communication with the outer chamber 156 via the openings 168. When fluid is provided to the inner chamber 158, the fluid is directed toward the inner portion 148 of the end wall 144 such that at least a portion of the fluid flowing through the openings 168 contacts the inner portion 148.

[0048] The lower portion 170 of the inner wall 154 defines a discharge opening 172. The discharge opening 172 enables fluid communication between the inner chamber 158 and the pin port 196 such that the pin port is in fluid receiving communication with the inner chamber 158 via the discharge opening 172.

[0049] The inner wall 154 defines an internal passage 178. The internal passage 178 is configured to receive a portion of the discharge plug 200. The discharge plug 200 is described in more detail herein with reference to Figures 8 - 11 more detail.

[0050] In some embodiments, during operation of the combustion chamber assembly 100, the piston head 140 translates axially within the cylinder 102. For example, combustion of the air-fuel mixture causes the piston head 140 to translate axially toward the connecting rod 110, and the connecting rod 110 causes the piston head 140 to translate axially away from the connecting rod 110. The piston head 140 may be heated by combustion of the air-fuel mixture in the cylinder 102.

[0051] A fluid (such as oil) is provided by a fluid injection system 120 to a piston head 140 to cool the piston head 140. The fluid may flow along a first flow path or a second flow path. For example, the fluid flowing along the first flow path enters the outer chamber 156 via an inlet port 166 and exits the outer chamber via an outlet port 167. The fluid flowing along the second flow path enters the outer chamber 156 via the inlet port 166, flows into the inner chamber 158 through an opening 168, and flows into a pin port 196 through a discharge opening 172. In some embodiments, an internal passage 178 is provided upstream of the discharge opening 172 such that a discharge plug 200 is located upstream of the discharge opening 172 and the fluid flows through the discharge plug 200 before flowing through the discharge opening 172.

[0052] In some embodiments, a first portion of the fluid is caused to flow along the first flow path (e.g., by gravity). The "sloshing" effect caused by the axial movement of the piston head 140 causes a second portion of the fluid to flow along the second flow path. More specifically, after the fluid enters the outer chamber 156, at least a portion of the fluid (e.g., the second portion of the fluid) sloshes due to the axial movement of the piston head 140 such that the second portion of the fluid flows through the opening 168 and into the inner chamber 158. The second portion of the fluid may contact the lower surface of the end wall 144 such that heat transfer from the end wall 144 to the fluid can be achieved. For example, since the central axis of the opening 168 is substantially parallel to the inner portion 148, the fluid can be directed toward the lower surface of the end wall 144. In some embodiments, the volume and / or mass of the second portion of the fluid is less than that of the first portion of the fluid.

[0053] In some embodiments, when the second portion of the fluid enters the pin port 196, the second portion of the fluid is also capable of achieving heat transfer from the connecting rod 110 and / or the pin 112 to the fluid. In some embodiments, the fluid may coat at least a portion of the connecting rod 110 and / or the pin 112 such that the fluid lubricates the connecting rod 110 and / or the pin 112.

[0054] Figure 8 is a perspective view of a piston head 140 according to another exemplary embodiment. Figure 8 The illustrated piston head 140 includes a discharge plug 200. The discharge plug 200 includes a mesh disk 204 and a retaining member shown as a snap ring 202. The retaining member (e.g., the snap ring 202) is configured to couple the mesh disk 204 to the piston head 140 at the internal passage 178 such that the discharge plug 200 is positioned upstream of the discharge opening 172.

[0055] Figure 9is a perspective view of the grid disk 204. As shown, the grid disk 204 includes an annular body 206, a grid portion 207, and an opening 208. The annular body 206 is configured to be received by the internal passage 178 such that the snap ring 202 couples the grid disk to the internal passage. The grid portion 207 includes a grid material, such as steel, plastic, or other suitable material, and allows fluid to flow through the grid portion 207. The grid portion 207 extends radially inwardly from the annular body 206. The grid portion 207 defines an opening 208 at the center of the grid disk 204. Fluid can also flow through the opening 208.

[0056] Figure 10 is a perspective view of the piston head 140 according to another exemplary embodiment. Figure 10 The illustrated piston head 140 includes a discharge plug 200. The discharge plug 200 includes a disk 210 and a retaining member shown as a snap ring 202. The snap ring 202 is configured to couple the disk 210 to the piston head 140 at the internal passage 178 such that the discharge plug 200 is positioned upstream of the discharge opening 172.

[0057] Figure 11 is a perspective view of the disk 210. The disk 210 includes an annular body 212 that includes a central opening 216 and one or more peripheral openings 214. The annular body 212 is configured to be received by the internal passage 178 such that the snap ring 202 couples the disk 210 to the internal passage. The one or more peripheral openings 214 are defined to axially pass through the annular body 212 and allow fluid to flow through the one or more peripheral openings 214. The annular body 212 also defines a central opening 216 at the center of the disk 212. Fluid can also flow through the central opening 212.

[0058] Figure 12 is a perspective view of the piston head 140 according to another exemplary embodiment. Figure 12 The illustrated piston head 140 does not include a discharge plug 200. The inner wall 154 does not include an internal passage 178.

[0059] It should be noted that the term "exemplary" as used herein to describe various embodiments is intended to indicate that such embodiments are possible examples, representatives, and / or illustrations of possible embodiments (and such term is not intended to mean that such embodiments must be particular or excellent examples).

[0060] The terms "couple", "connect", and similar terms as used herein mean that two members are joined to each other either directly or indirectly. Such joining can be fixed (e.g., permanent) or movable (e.g., removable or releasable). Such joining can be achieved by integrally forming the two members or the two members and any additional intermediate members into a single integral body or by attaching the two members or the two members and any additional intermediate members to each other.

[0061] References in this document to element positions (such as "top", "bottom", "above", "below", etc.) are for the purpose of describing the orientation of the various elements in the drawings only. It should be noted that, according to other exemplary embodiments, the orientations of different elements may be different, and such variations are intended to be covered by the present disclosure.

[0062] It is important to note that the construction and arrangement of the various exemplary embodiments are merely illustrative. Although only a few embodiments are described in detail in this disclosure, those skilled in the art who review this disclosure will readily recognize that many modifications (such as changes in the size, dimensions, structure, shape and proportions of the various elements, the values of parameters, the mounting arrangements, the use of materials, color, orientation, etc.) are possible without materially departing from the novel teachings and advantages of the subject matter described herein. For example, elements shown as integrally formed may be composed of multiple parts or elements, the positions of the elements may be reversed or otherwise changed, and the nature or number or position of discrete elements may be altered or varied. According to alternative embodiments, the order or sequence of any process or method steps may be changed or rearranged. Other substitutions, modifications, variations and omissions may also be made in the design, operating conditions and arrangements of the various exemplary embodiments without departing from the scope of the concepts provided herein.

[0063] Although this specification contains many details of specific embodiments, these should not be construed as limiting the scope of any invention or what may be claimed, but rather as descriptions of features specific to particular embodiments of a particular invention. Certain features described in the context of separate embodiments in this specification may also be implemented in combination in a single embodiment. Conversely, the various features described in the context of a single embodiment may also be implemented separately or in any suitable sub-combination in multiple embodiments. Additionally, although features may be described above as acting in a particular combination and even initially claimed as such, one or more features from the claimed combination may in some cases be deleted from the combination, and the claimed combination may be directed to a sub-combination or a variation of a sub-combination.

Claims

1. A piston head for a combustion cylinder, the piston head comprising: a lower portion of the piston head; and an upper portion of the piston head, the upper portion of the piston head being coupled to the lower portion of the piston head, the upper portion of the piston head comprising: --- an end wall including an outer portion and an inner portion angled relative to the outer portion; --- an outer wall axially extending away from the end wall in a first direction; and --- an inner wall axially extending away from the end wall in the first direction and separated from the outer wall such that an outer chamber is defined between the outer wall and the inner wall and an inner chamber is defined within the inner wall, the inner wall defining one or more openings fluidly connecting the inner chamber to the outer chamber, wherein an axis of each of the one or more openings is substantially parallel to the inner portion.

2. The piston head according to claim 1, wherein the lower portion of the piston head comprises: a piston head body; a skirt extending axially away from the piston head body and away from the upper portion of the piston head around a perimeter of the piston head body; and a pin port at least partially defined by the skirt.

3. The piston head according to claim 1, wherein the inner wall has a non-uniform cross-section.

4. The piston head according to claim 1, wherein the outer chamber is also defined by the outer portion of the end wall, wherein the outer chamber extends around a central axis of the piston head.

5. The piston head according to claim 1, further comprising: one or more inlet ports configured to receive fluid and supply the fluid to the outer chamber; and one or more outlet ports configured to receive fluid from the outer chamber and supply the fluid to a downstream device.

6. The piston head according to claim 1, wherein the one or more openings are defined through a top end of the inner wall near the end wall, and wherein the one or more openings are angled between 20° and 50° relative to a horizontal axis.

7. The piston head according to claim 1, wherein the upper portion of the piston head includes one or more annular passages extending around a perimeter of the outer wall in a radially outward direction.

8. A piston, comprising: the piston head according to any one of claims 1-7; a connecting rod; and a piston pin coupling the connecting rod to the piston head.

9. The piston according to claim 8, wherein the lower portion of the piston head includes a piston head body defining a first inlet port and a first outlet port.

10. The piston according to claim 9, wherein the lower portion of the piston head includes a skirt extending away from the piston head body, the skirt defining a pin port, wherein the inner chamber is in fluid communication with the pin port.

11. The piston according to claim 10, wherein the piston pin is received by the pin port.

12. The piston according to claim 10, wherein The lower portion of the inner wall defines a discharge opening that enables fluid communication between the inner cavity and the pin port such that the pin port is in fluid receiving communication with the inner cavity via the discharge opening.

13. The piston according to claim 12, wherein, the inner wall defines an internal passage configured to receive at least a portion of a discharge plug, and wherein the internal passage is disposed upstream of the discharge opening such that the discharge plug is located upstream of the discharge opening.

14. The piston according to claim 13, wherein, the discharge plug includes a grid disk and a retaining member configured to couple the grid disk to the piston head at the internal passage.

15. A cooling passage for a piston head of a combustion cylinder, the cooling passage comprising: an end wall including an outer portion and an inner portion angled relative to the outer portion; an outer wall axially extending away from the end wall in a first direction; and an inner wall axially extending away from the end wall in the first direction and separated from the outer wall such that an outer cavity is defined between the outer wall and the inner wall and an inner cavity is defined within the inner wall, the inner wall defining one or more openings fluidly connecting the inner cavity to the outer cavity, wherein an axis of each of the one or more openings is substantially parallel to the inner portion.

16. The cooling passage according to claim 15, wherein, the inner wall defines: a discharge opening; and an internal passage configured to receive a portion of a discharge plug, wherein the internal passage is disposed upstream of the discharge opening.

17. The cooling passage according to claim 16, wherein, the discharge plug includes: a grid disk including: --- an annular body configured to be received by the internal passage, --- a grid portion including grid material allowing the fluid to flow through the grid portion, and --- an opening, wherein the grid portion defines the opening at the center of the grid disk; and a retaining member configured to couple the grid disk to the piston head at the internal passage.

18. The cooling passage according to claim 16, wherein, the discharge plug includes: a disk including an annular body having a central opening and one or more peripheral openings; and a retaining member configured to couple the disk to the piston head at the internal passage.

19. The cooling passage according to claim 15, wherein, a value of a total volume of the cooling passage is equal to a reference value between 251% and 350% of a square of an inner diameter of the combustion cylinder.

20. The cooling passage according to claim 15, wherein, a value of a surface area of the cooling passage is equal to a reference value between 20.5% and 25% of a product of a square of an inner diameter of the combustion cylinder and a compression height of the combustion cylinder.

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