Gas injector with damper

Abstract

The invention relates to a gas injector for blowing in gaseous fuel, comprising an electromagnetic actuator (2) having an armature (20); a closing element (3) having a valve needle (30), which is connected to the armature (20), the closing element (3) releasing and closing a gas path (11) on a sealing seat (8); a closed lubricant chamber (4) in which the armature (20) is arranged; and a flexible sealing element (40) which seals the lubricant chamber (4) and enables axial mobility of the valve needle (30), the lubricant chamber (4) being filled with a liquid lubricant (5) and a gas (6).

Description

Technical Field

[0001] The invention relates to a gas injector for injecting gaseous fuel, in particular hydrogen, natural gas or the like, which has improved damping properties and has a short and compact axial structure. The gas injector is designed in particular for direct injection into a combustion chamber of an internal combustion engine. Background Art

[0002] A number of different designs of gas injectors are known from the prior art. A number of problems with gas injectors are due in principle to the fact that, due to the gaseous medium to be injected, lubrication by the medium is not possible, as is the case, for example, with fuel injectors that inject gasoline or diesel. This can lead to excessive wear during operation of the gas injector. Furthermore, the continuous miniaturization of internal combustion engines also requires that the gas injector occupy the smallest possible installation space. Summary of the invention

[0003] In contrast, the gas injector for injecting gaseous fuel according to the invention having the features of claim 1 has the advantage that an improved function can be achieved in combination with the lubrication of the movable parts of the gas injector. The gas injector according to the invention also has a very compact and short structure, especially in the axial direction of the gas injector. This is achieved according to the invention in the following way: the gas injector comprises an electromagnetic actuator with an armature, which can move in the axial direction of the gas injector. The armature is connected to a closing element of the gas injector, which has a valve needle in order to release and close the gas path for the gaseous fuel at the valve seat. In addition, a closed lubricant chamber is provided, which is filled with a liquid lubricant, wherein the axially movable armature is arranged in the lubricant chamber. Therefore, the lubricant ensures lubrication of the armature during operation, so that no wear occurs on the armature. The lubricant chamber comprises at least one flexible sealing element, in particular a bellows, which seals the lubricant chamber relative to the gas path. Therefore, the flexible sealing element ensures the axial movability of the closing element and constitutes a housing part of the lubricant chamber. In addition to the liquid lubricant, the lubricant chamber is also filled with a gas. Thus, a defined gas volume is present in the lubricant chamber, which enables the presence of a volume compensation unit integrated into the lubricant chamber in the event of a temperature increase that could lead to a volume expansion of the liquid lubricant. As a result, the flexible sealing element only has to ensure the mobility of the closing element in the axial direction, without additionally having to provide a temperature-induced compensation option for compensating for temperature-induced volume changes of the liquid lubricant in the lubricant chamber. This results in a compact flexible sealing element and, for example, in the case of a bellows, a significantly reduced axial length of the bellows.

[0004] The dependent claims reveal preferred embodiments of the invention.

[0005] The flexible sealing element is preferably a bellows, in particular a metal bellows. Due to the gas volume in the lubricant chamber, the axial length of the bellows can be selected to be very short, so that the bellows only has to ensure the axial mobility of the closing element of the gas injector. Alternatively, the flexible sealing element is a metal diaphragm, which can also be designed in a simplified manner due to the gas volume in the lubricant chamber.

[0006] Preferably, the gas injector further comprises a reset element, which is arranged in the lubricant chamber. The reset element resets the closing element to a closed initial position. Therefore, by being arranged in the lubricant chamber, reduced wear can also be achieved on the closing element during operation.

[0007] It is further preferred that the lubricant chamber comprises a deep-drawn part which forms a housing part of the lubricant chamber. The deep-drawn part is preferably designed in a pot-shaped manner and further preferably has a central filling opening which is closed by means of a closing unit. The filling opening is preferably located at the center axis of the gas injector. It is further preferred that the deep-drawn part is arranged at the end of the lubricant chamber which is remote from the combustion chamber.

[0008] Air, carbon dioxide or an inert gas is preferably used as the gas arranged in the lubricant chamber. The lubricant is preferably an oil or a liquid fuel or a perfluoropolyether (PFPE) or a heptane isomer or nonane.

[0009] At a temperature of 20°C, the pressure in the lubricant chamber is preferably between 1 and 4×10 5 Pa, especially 3×10 5 Pa. At 20° C., the pressure in the lubricant chamber is further preferably always greater than the 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. The volume of the liquid lubricant is further preferably at least twice as large as the volume of the gas in the lubricant chamber at 20° C.

[0011] Further preferably, a damping unit is arranged in the lubricant chamber. The damping unit preferably damps the closing movement of the closing element in order to avoid so-called rebound. Rebound occurs during rapid closing of the gas injector when the closing element strikes a stop and briefly rebounds, which can lead to an unintentional opening of the sealing seat.

[0012] Further preferably, the closing element is a closing element which opens outwards.

[0013] The flexible sealing element is preferably connected directly to the closing element, preferably by means of a welded connection. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings. In the accompanying drawings:

[0015] Figure 1 : A schematic cross-sectional view of a gas injector according to a first embodiment of the present invention;

[0016] Figure 2 : A schematic partial cross-sectional view of a gas injector according to a second embodiment of the present invention. DETAILED DESCRIPTION

[0017] Refer to the following Figure 1 A gas injector 1 according to a first preferred embodiment of the present invention will be described in detail.

[0018] As from Figure 1 It can be seen that a gas injector 1 for injecting gaseous fuel into a combustion chamber 10 comprises an electromagnetic actuator 2 which moves an outwardly opening closing element 3 from a closed state into an open state. Figure 1 The closed state of the gas injector is shown here.

[0019] The electromagnetic actuator 2 comprises an armature 20 and a coil 21, wherein the armature 20 is connected to the closing element 3. The closing element 3 comprises a valve needle 30 and a valve disk 31, which releases and closes a channel for injecting gaseous fuel on a sealing seat 8. The sealing seat 8 is formed between the valve disk 31 and the valve body 9.

[0020] The gas injector 1 further comprises a gas interface 91 through which the gaseous fuel is supplied to the gas injector. Reference numeral 11 designates a gas path extending through the gas injector 1. The valve body 9 is connected to the housing sleeve 90, for example by means of a welding connection. The gas path 11 extends radially outward from the gas interface 91 located centrally on the center axis XX of the gas injector and flows around the electromagnetic actuator 2.

[0021] The gas injector 1 further comprises a closed lubricant chamber 4 which receives the various components of the gas injector 1. The lubricant chamber 4 is filled with a liquid lubricant 5 and a gas 6.

[0022] Furthermore, the gas injector 1 comprises a reset element 7 which resets the closing element 3 to the position Figure 1 In the closed position shown, the restoring element 7 is likewise arranged within the lubricant chamber 4 .

[0023] The lubricant chamber 4 comprises a flexible sealing element 40, which is a metal bellows in this embodiment. In addition, the lubricant chamber 4 comprises a sleeve 41, which is connected to the coil 21 in a fixed position. A shoulder 41a is provided inside the sleeve 41, on which the first end of the reset element 7 is supported. The second end of the reset element 7 is supported on a spring disk 32, which is fixedly connected to the valve needle 30.

[0024] As from Figure 1 It can further be seen that the closing element 3 has a guide element 33 which is formed on the valve needle 30 in the region of the valve body 9 . The guide element 33 guides the closing element 3 on the inner circumference of the valve body 9 and has a plurality of recesses for the gas path 11 .

[0025] A deep-drawn part 42 is arranged at the end of the lubricant chamber 4 away from the combustion chamber, which closes the lubricant chamber 4. The deep-drawn part 42 is made of a thin metal material and has a substantially pot-shaped configuration. The deep-drawn part 42 has a filling hole 43, which is closed by a closing unit 44. The closing unit 44 includes, for example, a sealing ring 44a and a pin 44b.

[0026] A damping unit 12 is also arranged in the lubricant chamber 4, which damps the closing element 3 before it strikes the stop when the closing element 3 is retracted. The damping unit 12 is, for example, an elastic material at the end of the valve needle 30 facing away from the combustion chamber.

[0027] As from Figure 1 It can be seen that the volume of the liquid lubricant 5 in the lubricant chamber 4 is significantly greater than the volume of the gas 6. The volume of the gas in the lubricant chamber 4 is such that the volume of the gas is compressed while the volume of the liquid lubricant 5 expands due to an increase in temperature. It has been determined that during operation, the liquid lubricant 5 can expand by a maximum of 20% due to an increase in temperature. In this exemplary embodiment, at 20° C., the volume of the liquid lubricant 5 is twice as large as the volume of the gas 6.

[0028] Thus, the flexible sealing element 40 can be designed in such a way that it is only responsible for the axial mobility of the closing element 3 for opening and closing. In other words, the flexible sealing element 40 does not have to compensate for temperature-induced length changes caused by expansion of the liquid lubricant. As a result, the axial structural length of the gas injector can be significantly reduced.

[0029] The function of the gas injector according to the invention is as follows: When the electromagnetic actuator 2 is energized, the armature moves in the direction of the combustion chamber 10, whereby the closing element 3 is closed as in Figure 1 The valve disc 31 is thus lifted from the sealing seat 8, and gaseous fuel is blown in through the released passage on the sealing seat 8, which Figure 1 Indicated by arrow B.

[0030] To end the blowing, the electromagnetic actuator 2 is energized so that the closing element 3 is reset to the position by means of the reset element 7. Figure 1 In the closed position shown, the damping unit 12 prevents a so-called rebound 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.

[0031] The axial movement of the closing element 3 is here achieved only by means of the flexible sealing element 40. The temperature that rises during operation and that could lead to a volume expansion of the liquid lubricant 5 is compensated by compressing the gas 6 in the compressed lubricant chamber 4. This can cause a pressure increase in the lubricant chamber 4, which, however, has no negative impact on the function of the gas injector when opening and / or closing. The liquid lubricant is preferably oil and the gas 6 is preferably air.

[0032] Because the gas injector 1 is usually installed in the internal combustion engine in such a way that the sealing seat 8 points downward, such as Figure 1 As shown, the gas 6 is located substantially in the deep-drawn part 42. In principle, the installation position of the gas injector 1 in the internal combustion engine has no influence on the function of the lubricant chamber 4 filled with the liquid lubricant 5 and the gas 6 described above.

[0033] Therefore, a plurality of movable parts of the gas injector are arranged inside the lubricant chamber 4, so that the wear on these movable parts can be significantly reduced, thereby significantly extending the service life of the gas injector.

[0034] The flexible sealing element 40 is connected to the valve needle 30, for example, by means of a welded connection. Preferably, a welded connection is also provided between the flexible sealing element 40 and a sleeve 41 of the housing of the lubricant chamber 4. As a result, the lubricant chamber can be prefabricated and then provided for filling through the filling opening 43, wherein the filling of the gas 6 can also take place under pressure. After filling, the lubricant chamber 4 is closed by a closing unit 44, for example a pin.

[0035] Figure 2 A gas injector 1 according to a second embodiment of the invention is shown. Components which are identical or have the same function as in the first embodiment are denoted by the same reference numerals.

[0036] Unlike the first embodiment, the gas injector 1 of the second embodiment has a diaphragm made of metal and configured as a flexible sealing element 40. The diaphragm is connected to the valve needle 30 via a sleeve 45 and is connected to the base 12a of the damping unit 12 at the radial outer periphery. The damping unit 12 can achieve fluid communication between the first chamber 4a and the second chamber 4b of the lubricant chamber 4. The damping unit 12 can achieve damping both during the opening process of the closing element 3 and during the closing process of the closing element 3. As shown in FIG. Figure 2 It can be clearly seen that the use of a metal diaphragm as a flexible sealing element 40 enables a further reduction in the axial structural length of the gas injector 1. This allows a particularly compact structure to be achieved. A bellows is no longer required. The lubricant chamber 4 is configured with a pot-shaped part 46 at the end away from the combustion chamber, which essentially defines the receivable volume of the lubricant chamber 4. The volume size of the lubricant chamber 4 is selected according to the application. The filling of the lubricant chamber 4 can be achieved similarly to the first embodiment by means of a filling hole in the pot-shaped part 46, or as Figure 2 As shown, this is achieved by a filling opening 43 on the damping unit 12 which is closed by means of a closing ball 13. Otherwise, this exemplary embodiment corresponds to the preceding exemplary embodiments, so that reference is made to the relevant description there.

Claims

1. A gas injector for blowing gaseous fuel, comprising: - an electromagnetic actuator (2) having an armature (20); a closing element (3) having a valve needle (30), which is connected to the armature (20), wherein the closing element (3) opens and closes the gas path (11) at the sealing seat (8); - a closed lubricant chamber (4), in which the armature (20) is arranged; a flexible sealing element (40) which seals the lubricant chamber (4) and enables axial mobility of the valve needle (30), - wherein the lubricant chamber (4) is filled with liquid lubricant (5) and gas (6).

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

3. The gas injector according to any one of the preceding claims, further comprising a resetting element (7), wherein: The restoring element (7) is arranged inside the lubricant chamber (4).

4. The gas injector according to any of the preceding claims, further comprising a deep-drawn part (42), which is a housing part of the lubricant chamber (4).

5. The gas injector according to claim 4, wherein: The deep-drawn part (42) is of pot-shaped design and has a central filling opening (43) which is closed by means of a closing unit (44).

6. A gas injector according to any one of the preceding claims, wherein: The gas (6) is air, carbon dioxide or an inert gas, and / or Wherein, the liquid lubricant (5) is oil or perfluoropolyether or heptane isomer or nonane.

7. A gas injector according to any one of the preceding claims, wherein: The pressure in the lubricant chamber (4) is greater than the ambient pressure.

8. The gas injector according to claim 7, wherein: At 20°C, the pressure in the lubricant chamber (4) is 1×10 5 Pa to 4×10 5 Within the range of Pa.

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

10. The gas injector according to any one of the preceding claims, further comprising a damping unit (12), wherein: The damping unit (12) is arranged in the lubricant chamber (4).

Images