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US-12624650-B2 - Tapered engine exhaust valve

US12624650B2US 12624650 B2US12624650 B2US 12624650B2US-12624650-B2

Abstract

An exhaust valve for an internal combustion engine may comprise a body, including an upper portion, a lower portion, and a tapered portion between an upper end and a lower end of the body, wherein a ratio of (a) a length between an upper end of the upper portion and an upper end of the tapered portion to (b) a length between the upper end of the upper portion and a lower end of the tapered portion is in a range of 0.73 to 0.76, and a taper of the tapered portion is in a range of 0.0012/mm to 0.0030/mm. The exhaust valve may also comprise a head portion extending from a bottom of the lower portion of the body.

Inventors

  • Rachel M. Goldman Taylor
  • Adam D. Patrick
  • James D. Peltier
  • Abram M. Ingold

Assignees

  • CATERPILLAR INC.

Dates

Publication Date
20260512
Application Date
20240515

Claims (20)

  1. 1 . An exhaust valve for an internal combustion engine, the exhaust valve comprising: a body, including an upper portion, a lower portion, and a tapered portion between an upper end and a lower end of the body, wherein a ratio of (a) a length between an upper end of the upper portion and an upper end of the tapered portion to (b) a length between the upper end of the upper portion and a lower end of the tapered portion is in a range of 0.73 to 0.76, and a taper of the tapered portion, measured as a difference between a maximum diameter of the tapered portion and a minimum diameter of the tapered portion, divided by a length of the tapered portion, is in a range of 0.0012/mm to 0.0030/mm; and a head portion extending from a bottom of the lower portion of the body.
  2. 2 . The exhaust valve according to claim 1 , wherein an angle of the tapered portion is in a range of 0.03° to 0.09°.
  3. 3 . The exhaust valve according to claim 1 , wherein the body further includes a weld located within the tapered portion.
  4. 4 . The exhaust valve according to claim 1 , wherein the body has a guided length along which the exhaust valve is configured to move within a valve guide, and an upper end of the tapered portion is within the guided length and a lower end of the tapered portion coincides with a lower end of the guided length.
  5. 5 . The exhaust valve according to claim 4 , wherein a ratio of the guided length to a valve length is in a range of 0.2 to 0.5.
  6. 6 . The exhaust valve according to claim 1 , wherein the body is formed of one or more alloys.
  7. 7 . The exhaust valve according to claim 6 , wherein each alloy, of the one or more alloys, is selected from the group consisting of: 23-8N, an Inconel® alloy, and SIL1.
  8. 8 . An exhaust valve for an internal combustion engine, the exhaust valve comprising: a body including an upper portion, a lower portion, and a tapered portion between an upper end and a lower end, wherein a ratio of (a) a length between an upper end of the upper portion and an upper end of the tapered portion to (b) a length between the upper end of the upper portion and a lower end of the tapered portion is in a range of 0.77 to 0.79, and a taper of the tapered portion, measured as a difference between a maximum diameter of the tapered portion and a minimum diameter of the tapered portion, divided by a length of the tapered portion, is in a range of 0.0012/mm to 0.0031/mm; and a head portion extending from bottom of the lower portion of the body, wherein the exhaust valve is formed of one or more alloys, each alloy being selected from the group consisting of: 23-8N, an Inconel® alloy, and SIL1.
  9. 9 . The exhaust valve according to claim 8 , wherein an angle of the tapered portion is in a range of 0.05° to 0.12°.
  10. 10 . The exhaust valve according to claim 8 , wherein the body further includes a weld located within the tapered portion.
  11. 11 . The exhaust valve according to claim 8 , wherein the body has a guided length along which the body is configured to move within a valve guide, and both an upper end and a lower end of the tapered portion are within the guided length.
  12. 12 . The exhaust valve according to claim 11 , wherein a ratio of the guided length to a valve length is in a range of 0.25 to 0.50.
  13. 13 . The exhaust valve according to claim 8 , wherein the body and the head portion are formed of different alloys.
  14. 14 . A method of manufacturing an exhaust valve for an internal combustion engine, the method comprising: forging an exhaust valve to have: a body, including an upper portion, a lower portion, and a tapered portion between an upper end and a lower end, wherein a ratio of (a) a length between an upper end of the upper portion and an upper end of the tapered portion to (b) a length between the upper end of the upper portion and a lower end of the tapered portion is in a range of 0.73 to 0.76, and a taper of the tapered portion, measured as a difference between a maximum diameter of the tapered portion and a minimum diameter of the tapered portion, divided by a length of the tapered portion, is in a range of 0.0012/mm to 0.0031/mm; and a head portion extending from bottom of the lower portion of the body, wherein the exhaust valve is formed of one or more alloys.
  15. 15 . The method according to claim 14 , wherein an angle of the tapered portion is in a range of 0.03° to 0.09°.
  16. 16 . The method according to claim 14 , further comprising attaching at least two parts of the exhaust valve together, at an attachment point located within the tapered portion of the body of the exhaust valve.
  17. 17 . The method according to claim 16 , wherein the at least two parts are attached using welding, and the attachment point located within the tapered portion is a weld.
  18. 18 . The method according to claim 14 , wherein the body has a guided length along which the body is configured to move within a valve guide, and an upper end of the tapered portion is formed to be within the guided length and a lower end of the tapered portion is formed to coincide with a lower end of the guided length.
  19. 19 . The method according to claim 18 , wherein a ratio of the guided length to a valve length is in a range of 0.2 to 0.5.
  20. 20 . The method according to claim 14 , wherein each alloy, of the one or more alloys, is selected from the group consisting of: 23-8N, an Inconel® alloy, and SIL1.

Description

TECHNICAL FIELD The present disclosure relates generally to a tapered exhaust valve for an internal combustion engine, and, more particularly, to an engine exhaust valve having a body with a tapered portion. BACKGROUND In an internal combustion engine, exhaust valves move within valve guides in a head of the engine, between a closed position, in which the exhaust valve retains an air and fuel mixture in the combustion chamber during compression and combustion of the mixture, and an open position, in which the exhaust valve releases exhaust gases generated during combustion from the combustion chamber. The exhaust valves are subjected to extreme temperatures and extreme temperature changes, as well as corrosive exhaust gases generated during combustion. The extreme temperatures and extreme temperature changes cause the exhaust valves to change in size, including diameter or thickness, during operation. Specifically, when exhaust valves are exposed to the extremely high engine exhaust gas temperatures, the valves expand or increase in size. The temperature changes are also concentrated towards one end of the exhaust valve, that is, towards the end of the exhaust valve in contact with the exhaust gases and located nearest to a combustion chamber of the engine. Therefore, the exhaust valve is subjected to varying temperatures from one end to another. In addition, exhaust valves are sized to ensure a slight positive diametric clearance between the exhaust valve and the valve guide during operation, to allow for movement of the exhaust valve within the valve guide, while preventing the exhaust valve from sticking to the valve guide. At a start of engine operation, a valve guide may be at a relatively low temperature (i.e., a “cold guide”), whereas the exhaust valve may be at a relatively high temperature (i.e., “hot valve”), which could result in a reduction of diametrical clearance between the valve guide and the exhaust valve, and, in some cases, a negative diametrical clearance. Due to the relatively low diametrical clearance between exhaust valves and valve guides, and due to the extreme temperatures, extreme temperature changes and the resulting change in size, and the potential for a cold guide and hot valve, known exhaust valves are liable to thermally expand in size, and therefore stick to valve guides, which reduces the efficiency and performance of the engine, and in some cases, the exhaust valves may fail or break. Exhaust valves are also subjected to tensile forces applied by valve springs at upper ends of the exhaust valves, which can also cause exhaust valves to fail. Chinese Patent No. 212454567U (the '567 patent) provides for an exhaust valve for a diesel engine, the valve having a rod part and a disc part. The rod part includes first, second and third sections, with the second section decreasing in diameter from a minimum diameter, nearest the third section, to a maximum diameter nearest the first section. The rod sections are connected to adjacent rod sections and/or to the disc part using a circular arc transition connection. In addition, the rod sections are formed of nickel-based alloys, specifically, alloys having a nickel content between 20 and 40. However, the exhaust valve of the '567 patent may be improved with respect to one or more of sticking-prevention, manufacturing, and material. The tapered exhaust valves and related method of manufacture of the present disclosure may solve one or more of the problems set forth above and/or other problems in the art. The scope of the current disclosure, however, is defined by the attached claims, and not by the ability to solve any specific problem. SUMMARY In one aspect of the present disclosure, an exhaust valve for an internal combustion engine may comprise a body, including an upper portion, a lower portion, and a tapered portion between an upper end and a lower end of the body, wherein a ratio of (a) a length between an upper end of the upper portion and an upper end of the tapered portion to (b) a length between the upper end of the upper portion and a lower end of the tapered portion is in a range of 0.73 to 0.76, and a taper of the tapered portion is in a range of 0.0012/mm to 0.0030/mm; and a head portion extending from a bottom of the lower portion of the body. In another aspect of the disclosure, an exhaust valve for an internal combustion engine may comprise a body including an upper portion, a lower portion, and a tapered portion between an upper end and a lower end, wherein a ratio of (a) a length between an upper end of the upper portion and an upper end of the tapered portion to (b) a length between the upper end of the upper portion and a lower end of the tapered portion is in a range of 0.77 to 0.79; and a head portion extending from bottom of the lower portion of the body, wherein the exhaust valve is formed of a nickel-based alloy having a nickel content of 60% to 80%. In still another aspect of the present disclosure, a method