Gas injector with a magnetic actuator

Abstract

The present invention relates to a gas injector (1), comprising a magnetic actuator (2) which comprises a coil (21) and an armature (22), a closing element (3) which is connected mechanically to the armature (22) and is configured to open and to close a through-opening (4), a restoring element (5) which resets the closing element (4) into a closed state after an opening operation, and a sleeve (6) which is closed on the circumferential side and is configured to receive the closing element (3) with the armature (22) and the restoring element (5) in the interior. The coil (21) is arranged here radially outside the sleeve (6).

Description

[0001] Description

[0002] title

[0003] Gas injector with magnetic actuator

[0004] State of the art

[0005] The present invention relates to a gas injector and in particular to a gas injector which is designed for direct injection of a gaseous fuel into a combustion chamber of an internal combustion engine.

[0006] Gas injectors are known from the state of the art in various designs. Due to cost advantages and the high availability of gaseous fuels, such gaseous fuels have recently become increasingly popular. However, the gaseous medium makes it difficult to seal the gas injector from the outside. The use of highly volatile hydrogen, in particular, makes sealing the gas injector difficult. Furthermore, hydrogen can diffuse into metals, causing them to become brittle and leading to premature material fatigue. At the same time, gas injectors require highly dynamic actuators that enable the precise injection of large volumes of the gaseous medium. This requires high magnetic forces acting on an armature. However, the control of the gas injector can be significantly impaired by a leak-proof seal.

[0007] Disclosure of the invention

[0008] The gas injector according to the invention with the features of claim 1 has the advantage that it enables reliable sealing of the gas to be injected from the environment. At the same time, the gas injector also enables fast and powerful opening and closing processes. This is made possible according to the invention in that the gas injector comprises a magnetic actuator having a coil and an armature. Furthermore, the gas injector comprises a closing element which is mechanically connected to the armature and is designed to open and close a through opening. A restoring element, which is in particular a spring, holds the closing element in the closed state through a restoring force. The coil generates a magnetic field which exerts a magnetic force on the armature.This magnetic force allows the armature to overcome the restoring force and open the closing element, allowing gas to be injected through the through-opening. Furthermore, the gas injector has a circumferentially closed sleeve. At least the closing element, the armature, and the restoring element are located inside the sleeve. The coil of the magnetic actuator is mounted outside the sleeve. Thus, the sleeve provides a simple and reliable seal for the gas injector against escaping gas. At the same time, a thin sleeve enables dynamic control of the closing element by the coil of the magnetic actuator. Furthermore, the sleeve can protect parts of the gas injector, such as the coil, from hydrogen embrittlement.

[0009] The subclaims show preferred developments of the invention.

[0010] Preferably, the sleeve extends over the entire axial length of the gas injector. In particular, one axial end of the gas injector forms the injection end, and the other end of the gas injector forms the connection end. Thus, the gas flows along the entire length of the gas injector within the circumferentially closed sleeve, effectively preventing any lateral escape of the gas.

[0011] The gas injector further preferably comprises a first and a second annular pole disk, each with an L-shaped cross-section. The pole disks are arranged coaxially to one another, separated from one another by an intermediate region and at a distance A. The arrangement results in a cross-section of the two pole disks which describes a U-shape that is open radially outwards. The U-shape has a gap at a distance A. The windings of the coil run within the U-shaped cross-section. The pole disks are designed to conduct the magnetic field generated by the coil and to focus it in the gap between the first pole disk and the second pole disk. The sleeve can have a low magnetic permeability and attenuate the permeability of the magnetic field, so that the field strength acting on the armature decreases.Alternatively, the sleeve can be made of a ferromagnetic material with very high magnetic permeability, for example, so that the field lines are redirected past the armature and reduce the field strength at the armature. However, by focusing the field lines with the help of the pole discs, it is possible to direct the magnetic field in such a way that, despite a sealing sleeve between the coil and the armature, a sufficiently strong magnetic force acts on the armature, allowing it to dynamically open and close the gas injector. Preferably, the first and second pole discs have an identical inner diameter, which corresponds to the outer diameter of the sleeve.

[0012] The axial end of the first pole disk and / or the second pole disk preferably has an outward-facing chamfer. The chamfer further focuses the magnetic field toward the flattened end of the pole disk and the armature. This further increases the magnetic field strength acting on the armature, resulting in improved switching dynamics of the gas injector.

[0013] Further preferably, an axial end of the armature is arranged in the intermediate region between the first pole disc and the second pole disc in an open and / or closed state. When the upper or lower axial end of the armature is located in the intermediate region, the magnetic field generated by the coil and focused by the pole discs exerts a greater axial force on the armature than if no axial end were located between the pole discs. Thus, the arrangement of an axial end of the armature results in improved dynamics of the closing element.

[0014] Preferably, the gas injector has an axial stop, which is made in particular of a material with high magnetic permeability and forms an axial extension of the armature. A gap exists between the armature in the closed state and the axial stop, the height of which defines the maximum opening stroke H of the armature. The gap creates an increased magnetic resistance. The magnetic field of the coil thus generates a reluctance force on the armature in the direction of the axial stop.

[0015] Preferably, the axial distance A between the first pole disc and the second pole disc is greater than the maximum opening stroke H of the armature. This ensures that the axial end of the armature is always located in the intermediate area between the pole discs and that the actuator can exert a maximum opening force on the closing element.

[0016] In a further preferred embodiment of the invention, the sleeve in the intermediate region has a first wall thickness W1 that is thinner than a second wall thickness W2 at the axial height of the first and / or second pole disk. Thus, the sleeve is thinner in the intermediate region than in the surrounding region. By narrowing the sleeve in the intermediate region, the sleeve has a reduced shielding effect on the magnetic field lines that are concentrated in the intermediate region by the pole disks. Thus, by locally reducing the wall thickness, the field strength in the region of the armature can be increased, resulting in faster and more powerful opening and closing processes.

[0017] The sleeve is also preferably made of a metallic material. Metallic materials have low permeability to gases, which means that a metallic sleeve ensures reliable sealing of gas from the environment with minimal material requirements. Furthermore, metallic materials are easy to process and exhibit good mechanical and thermal properties.

[0018] In a further preferred embodiment of the invention, the sleeve is made of a ferromagnetic material, in particular a soft magnetic material. Ferromagnetic materials have high magnetic permeability, which redirects the magnetic field along the sleeve. By focusing the magnetic field with the help of the pole discs, a sufficiently strong field is present in the area of ​​the actuator to dynamically actuate it, despite the redirection of the magnetic field.

[0019] Preferably, the armature is a rotationally symmetrical body with a through-hole. The through-hole enables efficient gas flow through the gas injector and low pressure loss, thus enabling a high injection volume in a short time. The rotationally symmetrical shape with the through-hole places more material radially outside the rotation axis, close to the coil, allowing the magnetic field generated by the coil to act directly on the armature and generate a higher force.

[0020] Further preferably, the gas injector is configured to inject hydrogen.

[0021] Furthermore, the present invention relates to a gas internal combustion engine with at least one gas injector according to the invention, which injects gaseous medium directly into a combustion chamber of the gas internal combustion engine.

[0022] Short description of the drawings

[0023] Embodiments of the invention are described in detail below with reference to the accompanying drawings. In the drawing:

[0024] Figure 1 is a schematic sectional view of a gas injector according to a preferred embodiment of the invention, and

[0025] Figure 2 is a schematic, enlarged partial sectional view of the

[0026] Gas injector from Figure 1.

[0027] Embodiment of the invention

[0028] A gas injector 1 according to a preferred embodiment of the invention is described in detail below with reference to Figures 1 and 2.

[0029] As can be seen from Figure 1, the gas injector 1 comprises a circumferentially closed sleeve 6, which extends from an injection-side end 61 to a connection-side end 62 over the entire length of the gas injector. The sleeve is rotationally symmetrical about the axis X-X.

[0030] The gas injector is actuated by a magnetic actuator 2. The magnetic actuator 2 comprises a coil 21 and an armature 22. A closing element 3 is connected to the armature 22 and is designed to open and close a through-opening 4. The armature 22 is preferably made of a material with high magnetic permeability. The closing element 3 is released by energizing the coil 21, generating a magnetic field. The magnetic field exerts a magnetic force on the armature 22, which, together with the closing element 3, is set into axial movement and opens the through-opening 4. When the through-opening 4 is opened, the gas flows from the connection-side end 62 past the armature 22 and closing element 3, through the through-opening 4 and into a combustion chamber 8.

[0031] A return element 5 holds the closing element 3 in the closed state shown in Figure 1 and returns the closing element 3 to the closed state after an opening operation.

[0032] The armature 22, the closing element 3, and the return element 5 are arranged inside the sleeve 6 and are surrounded by the gas to be injected. The coil 21 of the magnetic actuator 2 is arranged outside the sleeve 6 and thus protected from the gas. The coil 21 is wound around the sleeve 6.

[0033] The armature 22 is a rotationally symmetrical component with a through-opening, which is arranged coaxially with the sleeve 6. The outer diameter of the armature 22 corresponds approximately to the inner diameter of the sleeve 6, with a clearance fit between the sleeve 6 and the armature 22 so that the armature 22 can move within the sleeve 6 with as little resistance as possible. Towards the exhaust-side end 61, the armature 22 tapers and has holes so that the gas can flow to the closing element both inside and outside the armature.

[0034] A first pole disk 7a and a second pole disk 7b are arranged between the coil 21 and the sleeve 6. The first pole disk 7a is arranged toward the connection-side end 62, and the second pole disk 7b is arranged toward the injection-side end 62. The inner diameter of the first pole disk 7a and the second pole disk 7b corresponds to the outer diameter of the sleeve 6 in the overlap area.

[0035] The pole disks 7a; 7b are arranged in a ring around the sleeve 6 and each have an L-shaped cross-section. One side is arranged parallel to the sleeve 6, and the other side is arranged perpendicularly. The sides of the first and second pole disks 7a; 7b, which are arranged parallel to the sleeve 6, form an axial end 73 at their ends. The axial ends 73 of the first pole disk 7a and the second pole disk 7b are arranged relative to one another. An intermediate region 71 is located between the first pole disk 7a and the second pole disk 7b. The intermediate region 71 separates the pole disks 7a; 7b from one another by a constant distance A.

[0036] Figure 2 shows a schematic, enlarged partial sectional view of the gas injector 1 from Figure 1. The partial sectional view shows the intermediate region 71 with sleeve 6, armature 22, return element 5, first pole disk 7a, second pole disk 7b and coil 21.

[0037] The first pole disk 7a and the second pole disk 7b have a chamfer 71 at their axial ends 73, which faces radially outward. The pole disks are preferably made of a material with high magnetic permeability, such as iron alloys. The pole disks 7a; 7b bundle the field lines of the magnetic field generated by the coil 21 and focus it between the axial ends 73 in the intermediate region 72.

[0038] Between the axial ends 73 of the pole disks 7a; 7b, the sleeve 6 has a reduced first wall thickness W1 compared to a thicker second wall thickness W2 at the axial height of the first and second pole disks 7a; 7b. The reduced first wall thickness W1 improves the permeability of the sleeve 6 to the magnetic field, so that the highest possible magnetic field strength is present in the region of the armature 22.

[0039] Figure 2 shows the armature 22 of the gas injector 1 in the closed state. The armature 22 has a maximum opening stroke H, which is limited by an axial stop 9. The axial stop 9 is preferably made of a material with high magnetic permeability. The connection-side axial end of the armature 22 is located between the axial ends 73 of the pole disks 7a; 7b in both the open and closed states. The magnetic field generated by the coil 21 flows through the second pole disk 7b, then through the sleeve 6 and the armature 22. The magnetic field then bridges a gap 10 between the armature 22 and the axial stop 9, before flowing from the axial stop 9 through the sleeve 6 to the first pole disk 7a. Alternatively, the magnetic field can also be directed in the opposite direction.

[0040] The magnetic resistance through the gap 10 results in a reluctance force on the armature 22 in the direction of the axial stop 9, so that the gap 10 is closed and the magnetic resistance is reduced.

[0041] Due to the high field strength of the magnetic field between the pole disks 7a; 7b and the reduced first wall thickness W1, it is possible to use a sleeve 6 made of a metallic or ferromagnetic material, which significantly reduces the permeability of the magnetic field into the interior of the sleeve 6, since the magnetic field strength is still large enough to dynamically actuate the armature 22 with the closing element 3.

Claims

Claims 1. Gas injector (1), comprising: a magnetic actuator (2) which comprises a coil (21) and an armature (22), a closing element (3) which is mechanically connected to the armature (22) and is designed to open and close a through-opening (4), a return element (5) which returns the closing element (4) to a closed state after an opening process, and a circumferentially closed sleeve (6) which is designed to receive the closing element (3) with the armature (22) and the return element (5) in its interior, - wherein the coil (21) is arranged radially outside the sleeve (6).

2. Gas injector (1) according to claim 1, wherein the sleeve (6) extends over the entire axial length of the gas injector (1).

3. Gas injector (1) according to one of the preceding claims, wherein the gas injector (1) has a first annular pole disk (7a) and a second annular pole disk (7b), each with an L-shaped cross-section, which are separated by an intermediate region (72) and arranged coaxially to one another at a distance (A), so that the two pole disks (7a; 7b) describe a U-shape open radially outwards.

4. Gas injector (1) according to claim 3, wherein the axial end (73) of the first pole disc (7a) and / or the second pole disc (7b) has a radially outwardly directed chamfer (71).

5. Gas injector (1) according to one of claims 3 or 4, wherein an axial end of the armature (22) is arranged in an open and / or closed state in the intermediate region (72) between the first pole disc (7a) and the second pole disc (7b).

6. Gas injector (1) according to one of claims 3 to 5, wherein the axial distance (A) between the first pole disc (7a) and the second pole disc (7b) is greater than the maximum opening stroke (H) of the armature (22).

7. Gas injector (1) according to one of claims 3 to 6, wherein the sleeve (6) in the intermediate region (72) has a first wall thickness (W1) which is thinner than a second wall thickness (W2) at the axial height of the first and / or second pole disk (7a; 7b).

8. Gas injector (1) according to one of the preceding claims, wherein the sleeve (6) is made of a metallic material.

9. Gas injector (1) according to one of the preceding claims, wherein the sleeve (6) is ferromagnetic.

10. Gas injector (1) according to one of the preceding claims, wherein the armature (22) is a rotationally symmetrical body with a through-opening along the axis of rotation (X - X).

11. Gas injector (1) according to one of the preceding claims, wherein the gas injector (1) is arranged to inject hydrogen.

12. Gas internal combustion engine, comprising a gas injector (1) according to one of the preceding claims, wherein the gas injector (1) blows directly into a combustion chamber (8) of the gas internal combustion engine.

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