Gas injector with a second seal seat controlled by negative pressure

Abstract

The present invention relates to a gas injector for injecting a gaseous medium, the gas injector comprising a closing element (2) for opening and closing a through opening (3) in a first sealing seat (4), an actuator (5) for operating the closing element (2), a return element (6) for returning the closing element (2), a second sealing seat (7) arranged between a gas supply connection piece (12) and the first sealing seat (4) in the flow direction of the gaseous medium and for opening and closing a gas flow path (A) in the gas injector, a negative pressure connection piece (80) arranged upstream of the second sealing seat (7) in the flow direction of the gas injector, and a regulating valve (8) fluidly connected to the negative pressure connection piece (80) and configured to connect the negative pressure connection piece (80) to a negative pressure source (81) and thereby open the second sealing seat (7).

Description

Technical Field

[0001] The present invention relates to a gas injector for injecting a gaseous medium, particularly hydrogen or natural gas, and having a second seal seat that is negatively pressure-controlled and can be opened.

[0002] Background Art Gas injectors are known in various different configurations based on the prior art. Compared to fuel injectors for liquid fuels, the technical requirements imposed on gas injectors are clearly different. One problem in gas injectors is the sealing of the gas injector over a longer period of time. In this case, for example, it must be avoided that gaseous fuel diffuses from the gas injector into the combustion chamber beyond the seal seat, which is normally closed, even in the case where the engine is stopped, and in some cases reaches the surrounding environment. However, this must be absolutely avoided.

[0003] Disclosure of the Invention A gas injector according to the present invention for injecting a gaseous medium, having the features described in claim 1, has the advantage of significantly reducing the potential loss of the gaseous medium from the gas injector, even when the gas injector is closed for a longer period of time, compared to conventional injectors. Furthermore, regarding the opening of the second seal seat, which is formed as an elastomer seal seat, in addition to improved sealing, reliable opening can be achieved even when the seal diameter of the second seal seat is large. The gas injector according to the present invention is extremely simple and inexpensive to construct. This is achieved by the gas injector having a closing element that opens and closes a through-opening provided in the seal seat. Furthermore, an actuator is provided for operating the closing element. The gas injector further includes a return element for returning the closing element. The second seal seat, positioned between the gas supply connection piece and the first seal seat in the direction of flow of the gaseous medium through the gas injector, opens and closes the gas flow path through the gas injector. The gas injector is equipped with a negative pressure connecting piece positioned upstream of the second seal seat in the direction of flow of the medium through the gas injector. Furthermore, the gas injector according to the present invention is equipped with a control valve positioned on the negative pressure connecting piece and configured to open the second seal seat by connecting this negative pressure connecting piece to a negative pressure source. This control valve is preferably a two-port, two-position valve. Thus, by providing two seal seats, the gastightness of the gas injector can be ensured even during longer periods of idleness and non-operation. Even assuming that the first seal seat directed toward the combustion chamber becomes unsealed, at least a certain amount of gaseous medium that may flow out of the gas injector is reduced to the volume between the first and second seal seats based on the second seal seat. Furthermore, by using a pneumatic operation with negative pressure to open the second seal seat, an extremely simple and inexpensive structure of the gas injector can be achieved. This also avoids thermal problems in the gas injector that may occur in electrically operated shutoff elements.

[0004] Preferred improved forms of the present invention are shown in the dependent claims.

[0005] Preferably, the second seal seat is formed between an axially movable piston element and a housing component. The piston element enables easy and reliable opening of the second seal seat using negative pressure.

[0006] Preferably, the gas injector further comprises a third seal seat positioned on the piston element. This third seal seat opens and closes the connection between the gas passage within the gas injector and the control valve. The piston element is reciprocable between the second seal seat and the third seal seat. Therefore, the second and third seal seats are not closed simultaneously.

[0007] Particularly preferably, the third seal seat is formed between a radially outward-facing flange provided on the piston element and a contact surface provided on the housing component. The housing component preferably also functions as a guide component for the piston element.

[0008] The piston element is preferably a hollow piston with a piston end face, at which a second seal seat is sealed. This second seal seat is preferably formed on a radially inward projection of the housing, so that the axial movement of the piston element can open and close the second seal seat. For this purpose, the hollow piston preferably has one or more through passages provided in the piston circumferential wall.

[0009] More preferably, the gas injector includes a control chamber formed around the outer circumference of the piston element and located within a connecting passage between the gas passage and the control valve. Preferably, a throttling is present between this control chamber and the gas passage. This throttling prevents the outflow of the gaseous medium from the gas passage into the negative pressure region of the gas injector formed by the open control valve. The throttling is preferably a throttling gap on the outer circumferential surface of the piston element relative to the housing component, or alternatively, the throttling is formed within the housing component, particularly the contact disc.

[0010] More preferably, the gas injector includes an accumulator located downstream of the control valve. Therefore, this accumulator is positioned between the control valve and the negative pressure source. More preferably, a throttling is provided between the accumulator and the negative pressure shaft. This ensures that, during the startup of the internal combustion engine, the gaseous medium present in the control volume for opening the second seal seat is not supplied all at once into the intake passage, which may be the negative pressure source of the internal combustion engine, and that an ignitable mixture is formed there. The accumulator, and in particular the throttling, allows for the slow release of the gaseous medium into the intake passage.

[0011] More preferably, an elastomer seal element with a retaining metal sheet is positioned in the second seal seat. The retaining metal sheet allows for the use of a simply constructed seal element, such as a standardized O-ring, and also enables the sealing ability of the seal element by providing a larger sealing surface between the seal element and the retaining metal sheet. Furthermore, the retaining metal sheet can provide a sufficient bulge chamber for elastic deformation of the seal element.

[0012] More preferably, the actuator is housed in a closed chamber. The closed chamber for the actuator is preferably sealed by a metal diaphragm. This prevents the actuator from coming into contact with a gaseous medium and avoids corrosion problems of the actuator's components.

[0013] Furthermore, the present invention relates to an internal combustion engine equipped with a gas injector according to the present invention. This internal combustion engine preferably includes an intake manifold of the internal combustion engine that is fluidly connected to the gas injector via a control valve as a negative pressure source. The opening of the connecting pipe between this intake manifold and the gas injector is preferably located downstream of the throttle valve in the intake manifold.

[0014] More preferably, the internal combustion engine is equipped with multiple gas injectors, all of which are connected to only one common control valve. This significantly reduces the investment cost of the injection system according to the present invention.

[0015] More preferably, the internal combustion engine is equipped with a catalyst, which is guided by a controlled amount of gaseous medium flowing out when a control valve is opened. Preferably, an accumulator for temporarily storing the gaseous medium is located in the connection path between the control valve and the catalyst, thereby ensuring that the gas injector is sufficiently temperature-controlled after a cold start and that the controlled amount of gaseous medium components can be converted into gaseous components that are not of concern to the environment.

[0016] Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. [Brief explanation of the drawing]

[0017] [Figure 1] This is a schematic cross-sectional view of a gas injector according to a first embodiment of the present invention in a closed state. [Figure 2] This is a magnified view of the second seal seat of the gas injector in Figure 1, in the closed state. [Figure 3] This is a schematic diagram of the second seal seat of the gas injector shown in Figure 1 when it is in the open state. [Figure 4] This is a schematic partial cross-sectional view and additional detail view of a gas injector according to a second embodiment in an open state. [Figure 5]Schematic partial cross-sectional view and additional detailed views of a gas injector according to a second embodiment in a closed state. [Figure 6] Schematic partial cross-sectional view of a gas injector according to a third embodiment in an open state. [Figure 7] Schematic partial cross-sectional view of a gas injector according to a fourth embodiment in an open state. [Figure 8] Schematic view of a gas injector according to a fifth embodiment of the present invention.

[0018] Preferred Embodiment of the Invention Hereinafter, referring to FIGS. 1 to 3, the gas injector 1 according to the first preferred embodiment of the present invention will be described in detail.

[0019] As is apparent from FIG. 1, the gas injector for injecting a gaseous medium, particularly for injecting hydrogen, comprises a closing element 2 in the form of a valve needle and an actuator 5. This actuator 5 is configured to operate the closing element and bring this closing element to an open position.

[0020] The actuator 5 is formed as a solenoid actuator having an armature 50 and an inner pole 51. The actuator 5 is disposed within a closed actuator chamber 53 sealed against the gaseous medium by a flexible metal diaphragm 52.

[0021] The closing element 2 opens the through-opening 3 provided in the first seal seat 4 and also closes the first seal seat 4. FIG. 1 shows the closed state of the gas injector 1. In the open state, the gaseous medium is blown into the combustion chamber 30.

[0022] The return element 6 returns the closing element back to the closed starting position shown in FIG. 1.

[0023] The gas injector 1 further comprises a second seal seat 7, which will be described in detail in FIGS. 2 and 3. In the closed state of the gas injector when the internal combustion engine is shut off, both the first seal seat 4 and the second seal seat 7 are closed. The second seal seat 7 is arranged far enough away from the combustion chamber 30. The actuator 5 is arranged between the first seal seat 4 and the second seal seat 7. Therefore, it is possible for the second seal seat 7 to have a seal element 70 made of an elastomer. This elastomer seal element 70 can provide extremely good sealing performance in the closed state, so that even during a longer downtime of the gas injector, gas will not diffuse into the gas chamber 10 located upstream of the first seal seat 4 through the second seal seat 7.

[0024] The elastomer seal element 70 is arranged in a groove provided on the piston end face 22 and mainly has a square cross-section with rounded corners.

[0025] The elastomer seal element 70 contacts the housing component 11 of the gas injector to perform sealing. This housing component 11 has a protruding portion 11a extending over the entire circumference, and the second seal seat 7 is formed on this protruding portion 11a.

[0026] Therefore, by using two seal seats, it is ensured that in the unused state of the gas injector 1, gaseous medium cannot flow from the inflow region 12 into the gas chamber 10 through the second seal seat 7.

[0027] Therefore, if the first seal seat 4 is not sealed, for example, due to thermal effects, the gas injector 1 will lose the maximum amount of gas volume present in the gas chamber 10 between the first seal seat 4 and the second seal seat 7.

[0028] The gas injector 1 further includes a negative pressure connection piece 80. This negative pressure connection piece 80 is located upstream of the second seal seat when viewed in the flow direction (arrow A) of the gas injector and has a control valve 8. This control valve 8 is a two-port, two-position valve. The control valve 8 is connected to the negative pressure connection piece 80, which is configured to be connected to a negative pressure source to open the second seal seat 7. In this embodiment, the negative pressure source is the intake pipe 81. A conduit 83 for connecting the control valve 8 and the intake pipe 81 opens in the intake pipe 81 in the region downstream of the throttle valve 82 when viewed in the flow direction (arrow B).

[0029] The gas injector 1 further comprises a third seal seat 9 and a piston element 20. This piston element 20 is formed as a hollow piston and comprises a circumferential wall region 21 and a piston end face 22. An elastomer seal element 70 is positioned on the piston end face 22 (see Figure 2). Furthermore, a plurality of through passages 24 are provided in the circumferential wall region 21, thereby allowing gas flow inside the gas injector when the piston element 20 is open (see Figure 3). In addition, a flange 23 is formed on the outer circumferential surface of the piston element 20, oriented radially outward. This flange 23 serves as a guide for the piston element 20.

[0030] A third seal seat 9 is formed between a flange 23 oriented radially outward and a contact disc 13 fixed in position on the housing component 11. A throttling gap 14 is provided between the peripheral wall region 21 of the piston element 20 and the contact disc 13. A control chamber 15 is formed between the flange 23 and the contact disc 13. This control chamber 15 is connected to a negative pressure connecting piece 80 via one or more control holes 16 and a radial gap 17.

[0031] The piston element 20 is further preloaded by a return spring 25 while closed at the second seal seat 7 (see Figure 2).

[0032] Therefore, the second seal seat 7 and the third seal seat 9 are configured such that neither seal seat is closed simultaneously. When the second seal seat 7 is fully open, the third seal seat 9 is closed. This is shown in Figure 3. The closing of the third seal seat 9 or the opening of the second seal seat 7 is provided by negative pressure from a negative pressure source.

[0033] The function of the gas injector 1 according to the present invention is as follows: When the internal combustion engine is started, negative pressure is generated in the intake manifold 81. When the internal combustion engine is started, the control valve 8 is also energized, which moves the control valve 8 from the closed position shown in Figure 2 to the open position shown in Figure 3. As a result, the control chamber 15 is connected to the negative pressure source via the control hole 16, the radial gap 17, and the connecting piece 80. As a result, the pressure in the control chamber 15 decreases, causing the piston element 20 to move axially toward the inlet region 12 against the spring force of the return spring 25, as shown by arrow C in Figure 2. As a result, the second seal seat 7 opens.

[0034] Figure 3 shows the second seal seat 7 in a fully open state, which allows the gaseous medium to flow into the gas chamber 10 through the hollow piston element 20 and the through passage 24, passing through the open second seal seat 7, as indicated by arrow A, and then into the combustion chamber 30 by operating the actuator 5.

[0035] As is further evident from Figure 3, the movement of the piston element 20 in the direction of arrow C significantly reduces the volume of the control chamber 15. With the second seal seat 7 fully open, the flange 23 is in contact with the contact disc 13. This prevents the gaseous medium from flowing from the inlet region 12 through the control chamber 15 and control hole 16 to the negative pressure connecting piece 18, and from there into the intake manifold through the open control valve 8, as the third seal seat 9 is closed.

[0036] A throttling gap 18 may be provided between the flange 23 and the housing component 11 to allow the piston element 20 to move. Here, some leakage does occur into the control chamber 15 through the throttling gap 18 and from there into the intake manifold through the open control valve 8, however, this leakage is minimal based on the length of the throttling gap 18.

[0037] Therefore, during the operation of the internal combustion engine, the control valve 8 is kept continuously open, thereby keeping the second seal seat 7 always open to inject the gaseous medium. Subsequently, the actual injection is performed by the opening and closing of the first seal seat 4 by the closing element 2.

[0038] Since the second seal seat 7 is opened by negative pressure, it is possible to select a very large seat diameter for the second seal seat 7. This is important because the gaseous medium has a much larger volume compared to the liquid fuel, and this volume must be injected into the combustion chamber 30 in a short time.

[0039] When the internal combustion engine is stopped, the control valve 8 is closed again due to the interruption of power supply to the control valve 8. At this time, the pressure in the control chamber 15 slowly increases again through the throttling gap 18. In addition, with the assistance of the return element 25, the piston element 20 is moved again to the closed position shown in Figure 2, thereby opening the third seal seat 9 and closing the second seal seat 7. The housing component 11 is provided with a stopper 11b that terminates the return movement of the piston element 20.

[0040] Therefore, when the internal combustion engine is shut off, the first seal seat 4 and the second seal seat 7 are closed, which eliminates the need to worry about the loss of gaseous medium during longer periods of inactivity.

[0041] Figures 4 and 5 show a gas injector 1 according to a second embodiment of the present invention. The same or functionally identical components are denoted by the same reference numerals as in the first embodiment.

[0042] Unlike the first embodiment, in the second embodiment, the elastomer seal element 70 is formed as an O-ring. Figure 4 shows the second seal seat 7 in an open state, and Figure 5 shows the second seal seat 7 in a closed state. As is clear from the additional enlarged view shown in Figure 4, the elastomer seal element 70 formed as an O-ring is held to the piston end face 22 by a retaining metal sheet 71. This creates a bulge chamber 72 that allows for elastic deformation of the elastomer seal element 70 internally. This is shown in the enlarged view of Figure 5. Therefore, it is possible to use a standardized and inexpensive elastomer seal element in the form of an O-ring. The configuration with the retaining metal sheet 71 further allows for increased axial tolerances. Therefore, the elastomer seal element 70 can be provided at a particularly low cost. The retaining metal sheet 71 is preferably joined to the piston element 20 by welding.

[0043] Figures 6 and 7 show gas injectors 1 according to third and fourth embodiments of the present invention. The same or functionally identical components are denoted by the same reference numerals as in the previous embodiments.

[0044] Unlike the previous embodiment, in the third and fourth embodiments, a lip seal 26 is positioned in the outer peripheral wall region of the flange 23 facing radially outward of the piston element 20. This lip seal 26 can influence the characteristics of the throttling gap 18. In particular, the lip seal 26 makes it possible to further reduce the amount of leakage into the control chamber 15 when the second seal seat 7 is open in these embodiments. For this purpose, a continuous reduced diameter portion 11c is provided in the housing component 11. In Figure 6, an additional throttling 14a is further formed in the contact disc 13. In Figure 7, an additional throttling is provided as the throttling gap 14. In other respects, these embodiments correspond to the previous embodiments, and the description therein can be referenced.

[0045] Figure 8 shows a gas injector 1 according to a fourth embodiment of the present invention. The same or functionally identical components are denoted by the same reference numerals as in the previous embodiments.

[0046] The fourth embodiment is substantially equivalent to the first embodiment. In the fourth embodiment, an accumulator 19 is provided in addition to the first embodiment. As is clear from Figure 8, this accumulator 19 is located between the control valve 8 and the negative pressure source in the form of the intake manifold 81. A throttle 19a is located at the outlet of the accumulator 19, thereby regulating and providing the outflow of the gaseous medium into the intake manifold 81. This causes the gaseous control amount present in the volume region from the control chamber 15 to the control valve 8 to flow out more slowly into the intake manifold 81. Thus, the amount of gaseous medium supplied to the internal combustion engine via the intake manifold is distributed over a longer period of time. This prevents, in particular, the formation of a flammable mixture in the intake manifold 81. In other respects, this embodiment is equivalent to the previous embodiment, so the above description can be used for further details.

Claims

1. A gas injector system comprising a gas injector for blowing a gaseous medium and a control valve (8), The aforementioned gas injector is A closing element (2) that opens and closes a through opening (3) provided in the first seal seat (4), An actuator (5) for operating the closing element (2), A return element (6) for returning the closing element (2), A second seal seat (7) is positioned between the gas supply connection piece (12) and the first seal seat (4) in the direction of flow of the gaseous medium, and opens and closes the gas passage (A) in the gas injector. A negative pressure connecting piece (80) is positioned upstream of the second seal seat (7) in the flow direction of the gas injector, It has, The control valve (8) is fluidly connected to the negative pressure connecting piece (80), and is configured to open the second seal seat (7) by connecting the negative pressure connecting piece (80) to a negative pressure source (81). The second seal seat (7) is formed between the axially movable piston element (20) and the housing component (11), A gas injector system comprising a third seal seat (9) positioned on the piston element (20) for opening and closing a connection between the gas passage in the gas injector and the control valve (8), wherein the piston element (20) is reciprocally movable between the second seal seat (7) and the third seal seat (9).

2. The gas injector system according to claim 1, wherein the third seal seat (9) is formed between a radially outward-facing flange (23) provided on the piston element (20) and a contact disc (13) provided on the housing component (11).

3. The gas injector further comprises a control chamber (15) formed on the outer circumference of the piston element (20), the control chamber (15) located in a connecting passage between the gas flow path within the gas injector and the control valve (8), according to claim 1.

4. The gas injector system according to claim 3, wherein a throttling (18) exists between the control chamber (15) and the gas flow path in the gas injector.

5. A gas injector system comprising a gas injector for blowing a gaseous medium and a control valve (8), The aforementioned gas injector is A closing element (2) that opens and closes a through opening (3) provided in the first seal seat (4), An actuator (5) for operating the closing element (2), A return element (6) for returning the closing element (2), A second seal seat (7) is positioned between the gas supply connection piece (12) and the first seal seat (4) in the direction of flow of the gaseous medium, and opens and closes the gas passage (A) in the gas injector. A negative pressure connecting piece (80) is positioned upstream of the second seal seat (7) in the flow direction of the gas injector, It has, The control valve (8) is fluidly connected to the negative pressure connecting piece (80), and is configured to open the second seal seat (7) by connecting the negative pressure connecting piece (80) to a negative pressure source (81). The second seal seat (7) is formed between the axially movable piston element (20) and the housing component (11), The gas injector system wherein the piston element (20) is a hollow piston having a piston end face (22) that seals the second seal seat (7).

6. A gas injector system comprising a gas injector for blowing a gaseous medium and a control valve (8), The aforementioned gas injector is A closing element (2) that opens and closes a through opening (3) provided in the first seal seat (4), An actuator (5) for operating the closing element (2), A return element (6) for returning the closing element (2), A second seal seat (7) is positioned between the gas supply connection piece (12) and the first seal seat (4) in the direction of flow of the gaseous medium, and opens and closes the gas passage (A) in the gas injector. A negative pressure connecting piece (80) is positioned upstream of the second seal seat (7) in the flow direction of the gas injector, It has, The control valve (8) is fluidly connected to the negative pressure connecting piece (80), and is configured to open the second seal seat (7) by connecting the negative pressure connecting piece (80) to a negative pressure source (81). The gas injector system further comprises an accumulator (19) fluidly connected to the negative pressure connecting piece (80), and the control valve (8) is positioned between the negative pressure connecting piece (80) and the accumulator (19).

7. A gas injector system comprising a gas injector for blowing a gaseous medium and a control valve (8), The aforementioned gas injector is A closing element (2) that opens and closes a through opening (3) provided in the first seal seat (4), An actuator (5) for operating the closing element (2), A return element (6) for returning the closing element (2), A second seal seat (7) is positioned between the gas supply connection piece (12) and the first seal seat (4) in the direction of flow of the gaseous medium, and opens and closes the gas passage (A) in the gas injector. A negative pressure connecting piece (80) is positioned upstream of the second seal seat (7) in the flow direction of the gas injector, It has, The control valve (8) is fluidly connected to the negative pressure connecting piece (80), and is configured to open the second seal seat (7) by connecting the negative pressure connecting piece (80) to a negative pressure source (81). The gas injector system has a second seal seat (7) having an elastomer seal element (70).

8. An internal combustion engine comprising the gas injector system according to claim 1, 5, 6, or 7.

9. The internal combustion engine according to claim 8, wherein the internal combustion engine has an intake pipe (81) as a negative pressure source, and the control valve is located in a connecting pipe between the intake pipe (81) and the negative pressure connecting piece (80).

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