Gas injector with attenuation body

Abstract

The present invention relates to a gas injector for injecting gaseous fuel, comprising a magnetic actuator (2) with an armature (20), a closure element (3) with a valve needle (30) coupled to the armature (20), the closure element (3) opening and closing a gas path (11) at a sealing seat (8), a closed lubricant chamber (4) in which the armature (20) is arranged, and a flexible sealing element (40) sealing the lubricant chamber (4) and allowing axial movement of the valve needle (30), the lubricant chamber (4) being filled with a liquid lubricant (5) and a gas (6).

Description

[Technical Field]

[0001] Background technology The present invention relates to a gas injector for injecting gaseous fuels, in particular hydrogen or natural gas, having improved damping characteristics and a short, compact axial configuration, the gas injector being designed in particular for direct injection into the combustion chamber of an internal combustion engine.

[0002] Gas injectors are known in various configurations in the prior art. The problem with gas injectors is that, in principle, the medium to be injected is gaseous, making lubrication by the medium impossible, as is the case with fuel injectors that inject gasoline or diesel. This results in excessive wear during operation of the gas injector. Furthermore, due to the trend toward smaller internal combustion engines, gas injectors must also occupy as little space as possible.

[0003] Disclosure of the Invention In contrast, the gas injector for injecting gaseous fuel according to the present invention, having the features of claim 1, has the advantage that improved lubrication of the moving parts of the gas injector is possible. Furthermore, the gas injector according to the present invention has a very compact and short structure, particularly in the axial direction of the gas injector. This is achieved, according to the present invention, by the gas injector having a magnetic actuator with a moving element movable in the axial direction of the gas injector. The moving element is connected to a closing element of the gas injector, which has a valve needle at a valve seat for opening and closing the gas path for the gaseous fuel. Furthermore, a closed lubricant chamber is provided, which is filled with a liquid lubricant, and the axially movable moving element is disposed within the lubricant chamber. The lubricant thus ensures lubrication of the moving element during operation, thereby preventing wear on the moving element. The lubricant chamber includes at least one flexible sealing element, particularly a bellows, which seals the lubricant chamber from the gas path. The flexible sealing element thus ensures the axial mobility of the closing element and forms part of the housing of the lubricant chamber. Furthermore, the lubricant chamber is filled with gas in addition to the liquid lubricant. A defined gas volume is therefore present in the lubricant chamber, which allows for a volume compensation unit to be integrated into the lubricant chamber in the event of a temperature rise, which could cause the volume of the liquid lubricant to expand. This means that the flexible sealing element only needs to ensure the axial mobility of the closing element, and no additional temperature compensation is required to offset the temperature-induced volume change of the liquid lubricant in the lubricant chamber. This results in a compact flexible sealing element, which, for example, significantly reduces the axial length of the bellows when a bellows is used.

[0004] The dependent claims describe preferred further configurations of the invention.

[0005] The flexible sealing element is preferably a bellows, in particular a metal bellows. The axial length of the bellows can be selected to be very short based on the gas volume present in the lubricant chamber, so that the bellows only needs to ensure the axial mobility of the closing element of the gas injector. Alternatively, the flexible sealing element can be a metal diaphragm, which can also simply be formed by the gas volume in the lubricant chamber.

[0006] Preferably, the gas injector further comprises a return element arranged inside the lubricant chamber, which returns the closing element to the closed starting position, so that reduced friction can likewise be achieved during operation of the closing element due to its arrangement inside the lubricant chamber.

[0007] More preferably, the lubricant chamber has a deep-drawn element formed as a housing part of the lubricant chamber. The deep-drawn element is preferably pot-shaped and more preferably has a central filling opening closed by a closing unit. The filling opening is preferably located on the central axis of the gas injector. More preferably, the deep-drawn element is arranged at the end of the lubricant chamber opposite the combustion chamber.

[0008] The gas disposed in the lubricant chamber is preferably air, CO2, or a noble gas, and the lubricant is preferably oil, liquid fuel, perfluoropolyether (PFPE), heptane isomer, or nonane.

[0009] The pressure in the lubricant chamber is preferably 1 to 4 × 10 at a temperature of 20 °C. 5 Pa range, especially 3 × 10 5 Pa. The pressure in the lubricant chamber at 20° C. is more preferably always higher than ambient pressure.

[0010] The volume of the liquid lubricant is greater than the volume of the gas in the lubricant chamber at a temperature of 20° C. More preferably, the volume of the liquid lubricant is at least twice the volume of the gas in the lubricant chamber at 20° C.

[0011] Furthermore, a damping unit is preferably arranged in the lubricant chamber, which preferably damps the closing movement of the closing element in order to prevent so-called collision recoil, which may occur during the high-speed closing process of the gas injector when the closing element abuts against the stop and bounces back after a short time, which may result in an undesired opening of the sealing seat.

[0012] More preferably, the closure element is an outward opening closure element.

[0013] Preferably, the flexible sealing element is directly connected to the closure element, preferably by a welded connection.

[0014] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a schematic cross-sectional view showing a gas injector according to a first embodiment of the present invention. [Figure 2] FIG. 4 is a schematic partial cross-sectional view showing a gas injector according to a second embodiment of the present invention.

[0016] Preferred embodiments of the invention In the following, a gas injector 1 according to a first preferred embodiment of the present invention will be described in detail with reference to FIG.

[0017] As can be seen in Figure 1, a gas injector 1 for injecting gaseous fuel into a combustion chamber 10 includes a magnetic actuator 2 which moves an outwardly opening closure element 3 from a closed state to an open state, in this case Figure 1 showing the gas injector in a closed state.

[0018] The magnetic actuator 2 comprises an armature 20 and a coil 21, the armature 20 being coupled to a closure element 3. The closure element 3 comprises a valve needle 30 and a valve disc 31, the valve disc opening and closing a flow passage for injecting gaseous fuel at a sealing seat 8. The sealing seat 8 is formed in this case between the valve disc 31 and a valve body 9.

[0019] The gas injector 1 further has a gas connection 91 through which gaseous fuel is supplied into the gas injector. Reference numeral 11 denotes a gas path extending through the gas injector 1. The valve body 9 is connected to a casing sleeve 90, for example by welding. The gas path 11 starts from the gas connection 91, which is centrally located on the central axis XX of the gas injector, and extends radially outward, flowing around the magnetic actuator 2.

[0020] The gas injector 1 further comprises a closed lubricant chamber 4, which accommodates several components of the gas injector 1. The lubricant chamber 4 is filled with a liquid lubricant 5 and a gas 6.

[0021] The gas injector 1 further comprises a return element 7, which returns the closing element 3 to the closed position shown in Figure 1. The return element 7 is likewise arranged inside the lubricant chamber 4.

[0022] The lubricant chamber 4 contains a flexible sealing element 40, which in this embodiment is a metal bellows. Furthermore, the lubricant chamber 4 further contains a sleeve 41 which is fixedly connected to the coil 21. The sleeve 41 has an internal step 41a on which a first end of the return element 7 is supported. A second end of the return element 7 is supported on a spring seat 32 which is rigidly connected to the valve needle 30.

[0023] 1, the closure element 3 has a guide element 33 which is formed on the valve needle 30 in the area of ​​the valve body 9. In this case, the guide element 33 guides the closure element 3 on the inner circumferential surface of the valve body 9 and has a number of openings for the gas channels 11.

[0024] A deep-drawn element 42 is arranged at the end of the lubricant chamber 4 opposite the combustion chamber, closing the lubricant chamber 4. The deep-drawn element 42 is made of a thin-walled metal material and has a substantially pot-like shape. The deep-drawn element 42 has a filling opening 43, which is closed by a closing unit 44. The closing unit 44 includes, for example, a sealing ring 44a and a cylindrical pin 44b.

[0025] A further damping unit 12 is arranged in the lubricant chamber 4, which enables damping of the closing element 3 before it abuts against the stop when it returns. The damping unit 12 is, for example, an elastic material provided on the end of the valve needle 30 facing away from the combustion chamber.

[0026] As can be seen from FIG. 1, the volume of the liquid lubricant 5 is significantly larger than the volume of the gas 6 in the lubricant chamber 4. The gas volume in the lubricant chamber 4 allows the gas volume to compress when the volume of the liquid lubricant 5 expands upon an increase in temperature. It has been determined that, upon operation, the liquid lubricant 5 can expand by up to 20% upon an increase in temperature. In this example, at 20° C., the volume of the liquid lubricant 5 is twice the volume of the gas 6.

[0027] This allows the flexible sealing element 40 to be designed such that it serves exclusively to facilitate the axial movement of the closure element 3 for opening and closing. In other words, the flexible sealing element 40 does not have to compensate for temperature-induced length changes due to the expansion of the liquid lubricant. This allows the axial construction of the gas injector to be significantly reduced.

[0028] The function of the gas injector according to the invention in this case is as follows: when the magnetic actuator 2 is energized, the armature is moved in the direction towards the combustion chamber 10, which causes the closing element 3 to open, as indicated by arrow A in Figure 1. This causes the valve 31 to lift off the sealing seat 8, and the injection of gaseous fuel takes place via the open conduit provided in the sealing seat 8, which is indicated by arrow B in Figure 1.

[0029] To end the injection, the magnetic actuator 2 is de-energized, so that the closing element 3 is returned again by the return element 7 to the closed position shown in Figure 1. The damping unit 12 then prevents a so-called crash reaction at the end of the closing element 3 facing away from the combustion chamber when the closing element 3 reaches its end position at the stop.

[0030] In this case, the axial movement of the closing element 3 is realized exclusively by the flexible sealing element 40. The temperature increase during operation, which can cause the volume of the liquid lubricant 5 to expand, is compensated by the compression of the gas 6 in the lubricant chamber 4. This may result in a pressure increase in the lubricant chamber 4, but this pressure increase does not adversely affect the function of the gas injector when opening and / or closing. Preferably, oil is used as the liquid lubricant, and air is used as the gas 6.

[0031] Typically, the gas injector 1 is installed in an internal combustion engine with the sealing seat 8 facing downwards, so that the gas 6 is located substantially within the deep-drawn part 42, as shown in Figure 1. However, the installation position of the gas injector 1 in an internal combustion engine does not fundamentally affect the above-mentioned function of the lubricant chamber 4 filled with the liquid lubricant 5 and the gas 6.

[0032] Therefore, since several moving parts of the gas injector are arranged inside the lubricant chamber 4, it is possible to significantly reduce the wear on these moving components, which can significantly extend the service life of the gas injector.

[0033] The flexible sealing element 40 is connected to the valve needle 30, for example, by a welded connection. Preferably, a welded connection is also provided between the flexible sealing element 40 and the sleeve 41 of the casing of the lubricant chamber 4. This allows the lubricant chamber to be prefabricated and then filled via the filling opening 43, which can also be filled with gas 6 under pressure. After filling, the lubricant chamber 4 is then closed by a closing unit 44, for example a cylindrical pin.

[0034] 2 shows a gas injector 1 according to a second embodiment of the present invention. Elements that are the same as or functionally the same as those in the first embodiment are given the same reference numerals.

[0035] Unlike the first embodiment, the gas injector 1 of the second embodiment has a metal diaphragm as the flexible sealing element 40. In this case, the diaphragm is connected to the valve needle 30 via a sleeve 45 and is connected at its radially outer periphery to the base body 12a of the damping unit 12. The damping unit 12 allows fluid communication from the first chamber 4a to the second chamber 4b of the lubricant chamber 4. The damping unit 12 provides damping during both the opening and closing of the closing element 3. As can be seen from FIG. 2, the use of a metal diaphragm as the flexible sealing element 40 further reduces the axial length of the gas injector 1, resulting in a particularly compact design. The use of a bellows is no longer necessary. At its end opposite the combustion chamber, the lubricant chamber 4 is configured with a pot 46, which essentially defines the lubricant chamber's volume. The size of the lubricant chamber 4's volume is selected depending on the application. The filling of the lubricant chamber 4 can be achieved by a filling opening in the pot 46, as in the first embodiment, or by a filling opening 43 in the damping unit 12, which is closed by a closing ball 13, as shown in Figure 2. In other respects, this embodiment corresponds to the previous embodiment, so reference can be made to the description given there.

Claims

1. 1. A gas injector for injecting gaseous fuel, comprising: a magnetic actuator (2) having a mover (20); a closure element (3) having a valve needle (30) connected to the armature (20), the closure element (3) opening and closing the gas path (11) at the sealing seat (8); a closed lubricant chamber (4) in which the armature (20) is located; a flexible sealing element (40) that seals the lubricant chamber (4) and allows axial movement of the valve needle (30); It has The lubricant chamber (4) is filled with a liquid lubricant (5) and a gas (6). Gas injector.

2. The gas injector of claim 1, wherein the flexible sealing element (40) is a bellows or a diaphragm.

3. 3. The gas injector according to claim 1, further comprising a return element (7), said return element (7) being arranged inside said lubricant chamber (4).

4. 4. The gas injector according to claim 1, further comprising a deep-drawn element (42), said deep-drawn element being a casing part of said lubricant chamber (4).

5. 5. The gas injector according to claim 4, wherein the deep-drawn element (42) is pot-shaped and has a central filling opening (43) that is closed by a closing unit (44).

6. 6. The gas injector according to claim 1, wherein the gas (6) is air, carbon dioxide, or a noble gas, and / or the liquid lubricant (5) is oil, perfluoropolyether, heptane isomer, or nonane.

7. 7. Gas injector according to any one of claims 1 to 6, wherein the pressure in the lubricant chamber (4) is higher than ambient pressure.

8. The pressure in the lubricant chamber (4) is 1 to 4 x 10 at 20°C. ５ 8. The gas injector of claim 7, wherein the pressure is in the range of 1000 psi to 1000 psi.

9. 9. The gas injector according to any one of claims 1 to 8, wherein the volume of the liquid lubricant (5) is greater than the volume of the gas (6) in the lubricant chamber (4).

10. 10. The gas injector according to any one of claims 1 to 9, further comprising a damping unit (12), said damping unit (12) being arranged in said lubricant chamber (4).

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