Gas injector with reduced wear

Abstract

The invention relates to a gas injector for injecting gaseous fuel, comprising: - a magnetic actuator (2) with an armature (20), an inner pole (21) and a coil (22), - a closing element (3) which releases and closes a gas path (14) at a valve seat (90), wherein the armature (20) is connected with the closing element (3), - a closed lubricant chamber (4) which is filled with a lubricant and in which the armature (20) is arranged, wherein the lubricant ensures lubrication of the armature (20), and - a flexible sealing element (5) which seals the lubricant chamber (4) against the gas path (14).

Description

Background Technology

[0001] This invention relates to a gas injector for injecting gaseous fuels, particularly hydrogen or natural gas or the like, which reduces wear, and is particularly suitable for internal combustion engines. The gas injector is specifically designed for direct injection into the combustion chamber of an internal combustion engine.

[0002] Various configurations of gas injectors are known in the prior art. A problem inherent in gas injectors, determined by their principle, is that lubrication via a medium, as is the case in fuel injectors for injecting gasoline or diesel fuel, is not feasible due to the gaseous nature of the injectable medium. This results in excessive wear during operation compared to fuel injectors used for liquid fuels. Therefore, gas injectors with improved wear behavior are desirable. Summary of the Invention

[0003] The gas injector for injecting gaseous fuel according to the present invention has the advantage of significantly reducing wear on the gas injector. This extends the service life of the gas injector and is substantially equivalent to the service life of a fuel injector for liquid fuel. This is achieved according to the invention by having a lubricant located in a closed lubricant chamber, in which the moving parts of the gas injector are arranged. The gas injector includes a magnetic actuator having an armature, an inner pole, and a coil.

[0004] Here, the armature is mechanically connected to a shut-off element that releases and closes the gas path at the valve seat, enabling movement for opening and / or closing the injector. The armature, located within the lubricant chamber, is thus situated inside the chamber and continuously supplied with and lubricated by lubricant. When the coil is energized, the armature is pulled towards the inner pole of the magnetic actuator by electromagnetic force. Consequently, wear at the armature is significantly reduced compared to gas injectors known to date in the prior art. To ensure the lubricant chamber's airtightness, a flexible sealing element is provided, which seals the lubricant chamber relative to the shut-off element in a partial area. Therefore, by using a closed lubricant chamber filled with lubricant, the service life of the gas injector can be significantly extended. Preferably, the lubricant chamber is completely filled with lubricant.

[0005] The preferred embodiments illustrate preferred extensions of the invention.

[0006] A further preferred embodiment is a braking device arranged in the lubricant chamber, configured to brake the closing element during its reset process. This reduces wear at the valve seat because braking the closing element during reset reduces the impact of the closing element on the valve body seat. The braking device also reduces the impact when the closing element strikes the valve body, especially since the valve seat is typically very dry and located in a hot combustion chamber atmosphere.

[0007] The braking device preferably includes a brake pin and a resilient braking element, such as a spring or elastic member. During the reset process, the brake pin can be engaged in an operative connection with the armature and / or the closing element, causing the armature to strike the brake pin before it actually stops at the stop portion, and causing the brake pin to move against the force of the elastic element, thereby achieving damping of the armature during the reset process. In particular, it reduces the armature speed. This is further supported by the additional mass acceleration provided by the braking device. Furthermore, further braking is achieved by the compression of lubricant between the armature and the brake pin. The reset speed of the closing element can be further reduced by the friction between the guide element or the like and the brake pin. All of this reduces the impact force on the armature at the stop portion, thus further extending the service life of the armature.

[0008] Particularly preferred is the arrangement of a brake guide element on the brake pin, which ensures stable movement of the guide pin. Furthermore, the brake guide element can additionally generate friction during the reset process of the closing element, providing additional damping.

[0009] Preferably, in the closed state of the injector, the axial clearance B between the brake guide element and the brake pin is less than the axial clearance C between the armature and the inner pole. Here, the axial clearance B between the brake guide element and the brake pin is in the range of 1% to 90% of the axial clearance C between the armature and the inner pole. Particularly preferably, the axial clearance B between the brake guide element and the brake pin is less than 25% of the axial clearance C, and more preferably in the range of 3% to 10% of the axial clearance C. The axial clearance C preferably has a size of 0.05 mm to 3 mm, especially 0.3 mm.

[0010] Preferably, oil, especially mineral oil, is used as a lubricant. Alternatively, liquid fuels, especially diesel or gasoline, may be used. Further alternatively, grease may be used as a lubricant.

[0011] More preferably, the flexible sealing element is a single-layer or multi-layer bellows. The bellows is preferably made of metal or, alternatively, of plastic. The bellows is preferably fixed directly to the closing element at one end and to the housing member of the gas injector at the other end. This fixing can be achieved, for example, by means of a weld in the case of a metal bellows.

[0012] Alternatively, the flexible sealing element is a membrane. The membrane can be single-layered or multi-layered and is fixed to the corresponding component, for example by laser welding, to seal the lubricant chamber.

[0013] Preferably, a gas path for the gaseous fuel is provided in the region between the valve housing and the actuator housing of the gas injector. This allows the actuator to be arranged within the housing and pre-assembled, at least partially, as a component. It also allows the lubricant chamber to be arranged within the actuator housing in a relatively simple manner.

[0014] Alternatively, the gas path of the gaseous fuel is formed through the region of the magnetic actuator, particularly through a coil chamber in which the coil of the magnetic actuator is arranged. This eliminates the need for a separate actuator housing for the magnetic actuator. It is particularly preferred that electrical contact be made through the gas path of the gaseous fuel. This significantly reduces the complexity of the gas injector structure. It should be noted that the electrical contact guided through the gas chamber must obviously be sealed relative to the outside.

[0015] Further preferably, a filter is arranged in the gas path for the gaseous fuel to filter out solid particles that may be present in the gaseous fuel, or to filter out solid particles that are determined by manufacturing or assembly. Further preferably, a guide member is also provided on the shut-off element, especially when the shut-off element is an elongated valve needle.

[0016] The gas injector is preferably an outward-opening injector. More preferably, the gas injector is pressure-balanced. Therefore, the force used to open the gas injector via the magnetic actuator is independent of the gas pressure. Consequently, the time used to open and close the injector after energization is also independent of the gas pressure. This allows operation at different gas pressures. The gas pressure can be reduced when the expected injection volume is small and increased when the expected injection volume is large. The injector is pressure-balanced when the average diameter of the bellows is equal to the diameter of the seat contact line between the closing element and the valve body. However, the average diameter of the bellows can also be smaller or larger than the seat diameter. In the first case, the total closing force acting on the valve needle is reduced when the gas pressure is higher, and the injector opens faster upon energization and closes more slowly after energization. This results in an increased gas injection volume. In the second case, the closing force acting on the valve needle is increased when the gas pressure is higher. This, in turn, compensates for the increased valve seat leakage due to the higher gas pressure.

[0017] Reset is preferably performed using a return spring. In pressure-balanced injectors, especially in the closed state of the gas injector, there is no pressure acting on the valve needle due to gaseous fuel, which significantly reduces the load on the closing element. Attached Figure Description

[0018] Embodiments of the present invention will now be described in detail with reference to the accompanying drawings. The drawings show:

[0019] Figure 1A schematic cross-sectional view of a gas injector according to a first embodiment of the present invention is shown;

[0020] Figure 2 Show Figure 1 A schematic enlarged partial cross-sectional view of a gas ejector;

[0021] Figure 3 Show Figure 1 Another schematic enlarged cross-sectional view of the gas injector;

[0022] Figure 4 A schematic partial cross-sectional view of a gas injector according to a second embodiment of the present invention is shown. Detailed Implementation

[0023] The following reference Figures 1 to 3 A gas injector 1 according to a first preferred embodiment of the present invention is described in detail.

[0024] from Figure 1 As can be seen from the image, the gas injector 1 includes a magnetic actuator 2 for introducing gaseous fuel, which causes the closing element 3, in this embodiment, an outwardly opening valve needle, to move from a closed state to an open state. Figures 1 to 3 This shows the gas injector in the off state.

[0025] The magnetic actuator 2 includes an armature 20, which is attached to the closing element 3 by means of an armature pin 24. In addition, the magnetic actuator 2 includes an inner pole 21, a coil 22, and a magnetic housing 23, which ensures the magnetic return of the magnetic actuator.

[0026] Furthermore, the gas injector 1 includes a body 7 having a connecting pipe 70 through which gaseous fuel is supplied. A valve housing 8 is fixed to the body 7, and a magnetic actuator 2 is arranged in the valve housing. The valve housing 8 is connected to a valve body 9 having a valve seat 90 at its free end, in which a closing element 3 releases and closes the passage for gaseous fuel.

[0027] exist Figures 1 to 3 The electrical connector 13 is schematically shown, which is guided to the magnetic actuator 2 via the body 7.

[0028] A retainer 12 is provided to secure the inner pole 21 to the valve body 9.

[0029] Reference numeral 10 marks the reset element for closing element 3, so that the closing element is reset again after the opening process. Figure 1 It is in the off state shown.

[0030] Figure 1The gas flow is also shown as a gas path 14 passing through the gas injector 1. Here, the gas flow begins at the connecting pipe and is then diverted 90° to the annular chamber 80 between the valve housing 8 and the main body 7. The gas flow 14 continues through the outer region of the magnetic actuator 2, through the filter 11 in the region of the closing element 3, until it reaches the valve seat 90. Here, corresponding openings not shown in the figure are provided in each component.

[0031] When the gas injector 1 opens, gaseous fuel flows through the outer periphery of the magnetic actuator 2 and the opened sealing seat 90 into the combustion chamber of the internal combustion engine. Figure 1 It is indicated by arrow A in the middle.

[0032] Therefore, the shut-off element 3 releases the gas path at the valve seat 90 and closes the gas path. For guidance, there is a first guide region 31 and a second guide region 32 between the shut-off element 3 and the valve body 9, which is... Figure 2 You can see the details in the middle.

[0033] In addition, the gas injector 1 includes a closed lubricant chamber 4. The lubricant chamber 4 is composed of... Figure 2 and Figure 3 As can be seen in detail, the closed lubricant chamber 4 is completely or partially filled with lubricant.

[0034] Depend on Figure 2 As can be seen, the lubricant chamber 4 is enclosed by the main body 7, the magnetic housing 23, the inner pole 21, and the flexible sealing element 5 in the form of a bellows. The flexible sealing element 5 provides a seal at the closing element 3. Therefore, the flexible sealing element 5 is fixed at its first end to the spring plate 16, which supports the reset element 10 for the closing element 3, and at its second end to the sleeve-shaped ring 15. Here, the flexible sealing element 5 compensates for the movement of the closing element 3 in the axial direction XX of the injector.

[0035] As from Figure 2 and Figure 3 As can be seen in detail, the armature pin 24, together with the armature 20 fixed thereon, is arranged in a closed lubricant chamber 4. Since the lubricant chamber 4 is filled with a lubricant, such as a liquid fuel, such as gasoline or diesel, or grease or the like, continuous lubrication of the armature 20 is achieved. This compensates for the problem of lack of lubrication of moving parts that occurs in the prior art when the fuel is in a gaseous state.

[0036] Depend on Figure 2 As can be seen, a filling channel 63 is constructed in the main body 7 to fill the closed lubricant chamber 4. The filling channel 63 is fluid-tightly sealed by a sealing sphere 64.

[0037] A braking device 6 is also arranged in the enclosed lubricant chamber 4. The braking device 6 includes a brake pin 60, a brake spring 61, and a brake guide element 62. The brake guide element 62 guides the brake pin 60 and is arranged on the inner periphery of the magnet housing 23 (see [link to relevant documentation]). Figure 2 and 3 ).

[0038] Here, the brake pin 60 is operatively connected to the armature via the armature pin 24.

[0039] Here, the braking device 6 has the following function: during the closing process of the gas injector 1, it brakes the closing element 3 together with the armature 20. This braking is achieved, on the one hand, by the braking spring force of the brake spring 61 on the brake pin 60, and on the other hand, by the braking force of the brake pin 60 and the fixed brake guide element 62 (see [reference]) when the brake pin 60 is lifted from the axial contact surface 65. Figure 3 This is achieved through hydraulic adhesion on the axial contact surfaces 65 between the two surfaces.

[0040] Additionally, when the closing element 3 resets, it is braked by friction in the brake guide element 62, and the armature pin 24 also partially extends into the brake guide element. Furthermore, the mass to be accelerated and the compression of lubricant in the closed lubricant chamber 4 result in additional braking during the closing process.

[0041] As from Figure 2 As can be seen, in the closed state, an axial gap C is provided between the armature 20 and the inner pole 21. An axial gap B is provided between the brake pin 60 and the brake guide element 62. The axial gap C between the armature 20 and the inner pole 21 is preferably in the range of 0.05 to 3 mm, and particularly preferably between 0.2 and 0.5 mm. When the coil 22 is energized, the armature 20 is pulled towards the inner pole 21, thereby causing the closing element 3 to enter the open state through the armature pin 24, allowing gaseous fuel to flow out into the combustion chamber. It should be noted that, in order to reduce magnetic flux leakage, the armature pin 24 and / or the sleeve ring 15 are made of a non-magnetic material.

[0042] The axial clearance B between the brake pin 60 and the brake guide element 62 is smaller than the clearance C between the armature 20 and the inner pole 21, and is closed by the spring force of the brake spring 61 during the opening process. Preferably, the clearance B is 1% to 90% of the clearance C. Thus, hydraulic adhesion of the brake pin 60 is achieved at the brake guide element 62 during the reset process.

[0043] exist Figures 1 to 3The gas injector 1 shown is pressure balanced. This means that the shut-off element 3 is connected to the flexible sealing element 5 via a spring plate 16, wherein the flexible sealing element 5, implemented as a metal bellows, has an average diameter D1, which is equal to the diameter D2 at the valve seat 90, where the shut-off element 3 seals the valve body 9. Consequently, no pressure is applied to the shut-off element 3, so the magnetic force required to open the shut-off element 3 can be kept very small, and especially independent of the pressure of the gaseous fuel.

[0044] It should be noted that, instead of bellows, membranes, hoses, or similar materials can also be used as sealing elements.

[0045] Therefore, the gas injector 1 can provide reduced wear in moving parts, especially in the valve seat 90, armature 20, and armature pin 24. Furthermore, the heat dissipation from the electromagnet actuator 2 can be significantly improved through the enclosed lubricant chamber 4 containing liquid lubricant.

[0046] Figure 4 A gas injector 1 according to a second embodiment of the present invention is shown. Components that are identical or functionally identical are labeled as in the first embodiment.

[0047] As from Figure 4 As can be seen, the structure of the gas injector 1 is in principle the same as that of the first embodiment. However, the difference lies in the different guidance of the gas path 14 in the region of the magnetic actuator 2. Here, in the second embodiment, the gas path 14 passes through the coil chamber at the magnetic actuator 2, in which the coil 22 is arranged. The gas path 14 passes through the opening in the magnetic canister 25. This eliminates the need for a valve housing. The electrical connector 13, in the form of a contact pin, is isolated from the body 7. Furthermore, the first guide region 31 of the closing element 3 is provided on the outer periphery of the spring plate 16. The spring plate 16 here has a corresponding opening for the gas path 14. The lubricant chamber 4 is encapsulated accordingly in the first embodiment and provides lubrication for the armature 20 during the opening and closing of the gas injector 1.

[0048] In other respects, this embodiment corresponds to the first embodiment, so that reference may be made to the description given there.

Claims

1. Gas injector for injecting gaseous fuel, the gas injector comprising: - a magnetic actuator (2) with an armature (20), an inner pole (21) and a coil (22), - a closing element (3) which releases and closes a gas path (14) at a valve seat (90), wherein the armature (20) is connected with the closing element (3), - a closed lubricant chamber (4) which is filled with a lubricant and in which the armature (20) is arranged, wherein the lubricant ensures lubrication of the armature (20), and - a flexible sealing element (5) which seals the lubricant chamber (4) against the gas path (14), wherein a brake device (6) is arranged in the lubricant chamber (4), which is provided for braking the closing element (3) during a reset process of the gas injector from an open state to a closed state, wherein the brake device (6) has a brake pin (60) and a resilient brake element (61), wherein the brake pin (60) and the resilient brake element (61) can be brought into operative connection with the closing element (3) and / or with the armature (20) during the reset process.

2. The gas injector of claim 1, wherein, The brake pin (60) is guided in the lubricant chamber (4) in a brake guide element (62).

3. The gas injector of claim 2, wherein, In the closed state of the injector, a first axial gap (B) between the brake guide element (62) and the brake pin (60) is smaller than a second axial gap (C) between the armature (20) and the inner pole (21).

4. The gas injector according to one of claims 1 to 3, wherein The closed lubricant chamber (4) is completely or partially filled with a lubricant.

5. The gas injector according to one of claims 1 to 3, wherein The flexible sealing element (5) is a bellows or a membrane.

6. Gas injector according to one of claims 1 to 3, - wherein a gas path (14) for the gaseous fuel extends in the region between a valve housing (8) and a magnetic housing (23) of the magnetic actuator (2), or - the gas path (14) of the gaseous fuel extends through a region of the magnetic actuator (2).

7. The gas injector according to one of claims 1 to 3, wherein The gas injector is an outwardly opening injector.

8. The gas injector of one of claims 1 to 3, wherein An average diameter Dl of the flexible sealing element (5) is equal to a diameter D2 of the valve seat (90) at which the closing element (3) releases and closes the gas path at a valve body (9).

9. The gas injector of claim 4, wherein, The lubricant is motor oil or gasoline or diesel or grease.

10. The gas injector of claim 5, wherein, The flexible sealing element (5) is a metal bellows.

11. The gas injector of claim 6, wherein, The gas path (14) of the gaseous fuel extends through a region of the magnetic actuator (2) in which the coil (22) is arranged. The gas path (14) of the gaseous fuel extends through a region of the magnetic actuator (2) in which the coil (22) is arranged.

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