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EP-4739899-A1 - GAS INJECTOR, IN PARTICULAR FOR HIGH COMBUSTION CHAMBER PRESSURES

EP4739899A1EP 4739899 A1EP4739899 A1EP 4739899A1EP-4739899-A1

Abstract

The present invention relates to a gas injector for injecting a gaseous medium, said gas injector comprising: an outwardly open valve needle (2); a valve body (3); a sealing seat (4) on the valve body (3), against which sealing seat the valve needle (2) forms a seal when the gas injector is in the closed state, the valve body (3) being hollow-cylindrical with a combustion-chamber-side end face (30), an outer lateral region (31), and an inner lateral region (32), the sealing seat (4) being arranged on the end surface (30) of the valve body (3), the valve body (3) having a combustion-chamber-side end region (33) on the outer lateral region (31), and a first recess (5) being formed in the outer lateral region (31) of the combustion-chamber-side end region (33) so that a wall thickness of the valve body (3) in the region of the first recess (5) is reduced to a first wall thickness (W1) which is the smallest wall thickness of the combustion-chamber-side end region (33).

Inventors

  • MUELLER, MARTIN
  • KOENINGER, ANDREAS

Assignees

  • Robert Bosch GmbH

Dates

Publication Date
20260513
Application Date
20240515

Claims (13)

  1. 1. Gas injector for injecting a gaseous medium, comprising: - an outward opening valve needle (2), - a valve body (3), - a sealing seat (4) on the valve body (3) to which the valve needle (2) seals when the gas injector is closed, - wherein the valve body (3) is hollow-cylindrical with a combustion chamber-side end surface (30), an outer jacket region (31) and an inner jacket region (32), - wherein the sealing seat (4) is arranged on the end face (30) of the valve body (3), - wherein the valve body (3) has an end region (33) on the combustion chamber side, and - wherein the end region (33) on the combustion chamber side is designed such that during a closing process of the gas injector no or at most a minimal tangential force occurs between the valve body (3) and the valve needle (2).
  2. 2. Gas injector according to claim 1, wherein the valve body (3) has a first recess (5) in the outer casing region (31), so that a wall thickness of the valve body (3) in the region of the first recess (5) is reduced to a first wall thickness (W1), which is the smallest wall thickness of the combustion chamber-side end region (33).
  3. 3. Gas injector for injecting a gaseous medium, comprising: - an outward opening valve needle (2), - a valve body (3), - a sealing seat (4) on the valve body (3) to which the valve needle (2) seals when the gas injector is closed, - wherein the valve body (3) is hollow-cylindrical with a combustion chamber-side end surface (30), an outer jacket region (31) and an inner jacket region (32), - wherein the sealing seat (4) is arranged on the end face (30) of the valve body (3), - wherein the valve body (3) has a combustion chamber-side end region (33) on the outer jacket region (31), and - wherein a first recess (5) is formed in the outer casing region (31) of the combustion chamber-side end region (33), so that a wall thickness of the valve body (3) in the region of the first recess (5) is reduced to a first wall thickness (W1), which is the smallest wall thickness of the combustion chamber-side end region (33).
  4. 4. Gas injector according to claim 2 or 3, wherein the first recess (5) is a circumferential groove, in particular with a constant depth.
  5. 5. Gas injector according to one of the preceding claims, wherein the combustion chamber-side end region (33) has an outer partial region (33a) and an inner partial region (33b), wherein the outer partial region (33a) forms an end of the valve body (3) directed towards the combustion chamber, wherein the first recess (5) is formed in the outer partial region (33a).
  6. 6. Gas injector according to one of the preceding claims, wherein the inner jacket region (32) is cylindrical.
  7. 7. Gas injector according to one of the preceding claims, wherein the valve needle (2) has a needle (20) with a valve plate (20a), wherein the valve plate (20a) seals at the sealing seat (4) of the valve body (3) when the gas injector is in the closed state.
  8. 8. Gas injector according to claim 7, wherein the valve plate (20a) has a second recess (50) on a combustion chamber side of the valve plate (20a).
  9. 9. Gas injector according to claim 8, wherein the second recess (50) is a circumferential groove and/or a central depression whose center lies in a central axis of the gas injector.
  10. 10. Gas injector according to one of the preceding claims, wherein the end surface (30) of the valve body (3), on which the sealing seat (4) is formed, is conical with a seat angle (a) in a range of 90° to 130°, in particular 100° to 120°, further in particular 105° to 117°, further in particular 110° to 112° and further in particular 111°.
  11. 11. Gas injector according to one of claims 7 to 10, wherein the valve plate (20a) is formed on an outer circumference in an arcuate section with a radius (R1), so that in the closed state of the gas injector a cone-ball seal is produced at the sealing seat.
  12. 12. Gas injector according to one of claims 7 to 11, wherein the valve needle (2) has a conical valve plate (20a), wherein the conical valve plate (20a) is designed such that in the closed state of the gas injector a free space (8) is present between an inner side of the valve plate (20a) facing away from the combustion chamber and a valve seat plane (E), wherein the valve seat plane (E) is perpendicular to an axial direction X-X and the sealing seat (4) is arranged in the valve seat plane.
  13. 13. Gas injector according to one of the preceding claims, wherein the first wall thickness (W1) satisfies the following equation: - 0.5 x W2 < W1 < 0.75 x W2, - where W2 is a constant, second wall thickness of the valve body at an outer portion (33a) in which the first recess (5) is formed.

Description

Description title gas injector, especially for high combustion chamber pressures State of the art The present invention relates to a gas injector for injecting a gaseous medium, such as hydrogen, natural gas, methane, LPG, ammonia or the like, into a combustion chamber of an internal combustion engine. Gas injectors are known from the state of the art in various designs. In comparison with injectors for liquid fuels, gas injectors require significantly larger flow cross-sections, since the volume of the gaseous medium is significantly larger than that of liquid fuels for the same energy content. This larger volume therefore actually requires larger diameters at the end of the gas injector near the combustion chamber, but this is difficult due to efforts to downsize internal combustion engines. In conventional internal combustion engines, at least two inlet and two outlet valves and, if necessary, an ignition source are arranged in the combustion chamber, which means that the installation space for the gas injector is very small. It should also be noted that in turbocharged internal combustion engines, compression is high during the injection period, so that the injection period is relatively short. The high pressures in the combustion chamber can also lead to geometric deformations on a valve body or a valve needle of the gas injector during operation, which can lead to undesirable sliding contacts between the valve needle and the valve body, particularly during the closing process of the gas injector, which can lead to undesirable disruption or wear with possible subsequent leaks. disclosure of the invention The gas injector according to the invention for blowing in a gaseous medium with the features of claim 1 has the advantage that wear, in particular on a sealing seat between a valve needle and a valve body of the gas injector, is significantly reduced. This can be achieved even at very high combustion chamber pressures, for example in turbocharged internal combustion engines. Furthermore, a predetermined, exact closing time can be reliably maintained during operation. This is achieved according to the invention in that the gas injector has a valve needle that opens outwards and a valve body. A sealing seat is formed on the valve body, against which the valve needle seals when the gas injector is closed. Furthermore, the valve body is hollow-cylindrical with an end face on the combustion chamber side. The sealing seat is arranged on the end face on the combustion chamber side. Furthermore, the valve body has an inner and an outer casing region, with an end region on the combustion chamber side being formed on the outer casing region, which is designed to be connected to the combustion chamber when the gas injector is mounted in a cylinder head or the like. The end region of the outer casing region of the valve body on the combustion chamber side is thus exposed to the combustion chamber gases and the high combustion chamber pressure. Furthermore, the end region on the combustion chamber side is designed in such a way that when the gas injector closes, no or at most a minimal tangential force, preferably a maximum of 5 N, in particular a maximum of 2 N, occurs between the valve body and the valve needle. This tangential force is defined as a thrust force in the valve seat plane that is perpendicular to the axial axis of the gas injector. Thus, no sliding takes place between the valve needle and the valve body during the closing process. This results in less disruption and reduced wear at this point. The gas injector according to the invention for blowing in a gaseous medium with the features of claim 3 has the advantage that wear, in particular on a sealing seat between a valve needle and a valve body of the gas injector, is significantly reduced. This can be achieved even at very high combustion chamber pressures, for example in turbocharged internal combustion engines. Furthermore, a predetermined, exact closing time can be reliably maintained during operation. This is achieved according to the invention in that the gas injector has a valve needle that opens outwards and a valve body. A sealing seat is formed on the valve body, against which the valve needle seals when the gas injector is closed. Furthermore, the valve body is designed as a hollow cylinder with an end face on the combustion chamber side. The sealing seat is arranged on the end face on the combustion chamber side. Furthermore, the valve body has an inner and an outer casing region, with a combustion chamber side end region being formed on the outer casing region, which is designed to be connected to the combustion chamber when the gas injector is mounted in a cylinder head or the like. The combustion chamber side end region of the outer casing region of the valve body is thus exposed to the combustion chamber gases and the high combustion chamber pressure. Furthermore, the combustion chamber side end region of the valve body has a fir