Gas metering valve for internal combustion engines

Abstract

Gas metering valve for internal combustion engines, having a housing (1) in which a gas space (2) is configured, which has a gas inlet (5) and a gas outlet (6). In the gas space (2) a movable valve element (8) is arranged, which can be moved by an electric actuator (16) against the force of a return spring (17) and which cooperates with a valve seat (11) to open and close the gas inlet (5). Between the valve element (8) and the gas outlet (6) a shut-off valve (25) is arranged, which opens in the flow direction to the gas outlet (6) and shuts off the opposite flow direction.

Description

Technical Field

[0001] The present invention relates to a gas dispensing valve, which is preferably used to directly dispense gaseous fuel into the combustion chamber of an internal combustion engine. Background Technology

[0002] Gas valves for dispensing gas in a metered manner are known from the prior art. DE 10 2016 215 027 A1 describes a gas valve as part of a recirculation device for a fuel cell assembly. The gas valve includes a movable valve element that is movable within the gas valve against the force of a spring element via an electromagnet, thereby opening and closing the inlet. Gas flow is guided through a borehole within the valve element and thus reaches the outlet, wherein the valve element is guided externally within the gas valve. By turning the electromagnet on and off, the required amount of gas can be supplied to the fuel cell at a desired time and in the desired quantity. In this application, excessive heat load on the seals of the valve element is undesirable.

[0003] However, the requirements are different when directly dispensing gas into the combustion chamber of an internal combustion engine. In the combustion chamber, high temperatures and pressures arise due to combustion, causing intense heating of the gas dispensing valve, which is directly connected to the combustion chamber. For example, if hydrogen is to be dispensed, a good seal can only be achieved with difficulty using a metal seat, primarily because a reliable seal is absolutely necessary for the entire service life of the dispensing valve for safety reasons. Therefore, the use of elastomeric seals is necessary; however, these elastomeric seals can only be exposed to relatively low temperatures without damage. To limit the temperature, the valve seat of the gas dispensing valve can be arranged relatively far from the exhaust port and therefore from the combustion chamber. However, this makes the gas dispensing valve more susceptible to backfire from the flame in the combustion chamber, because the relatively large-volume gas dispensing valve is directly connected to the combustion chamber due to the seal being far from the combustion chamber. Especially when the residue of combustible gas is located in the gas metering valve, the flame front of the combustion space will spread into the gas metering valve and cause a strong thermal load there, especially on the sealing seat. Summary of the Invention

[0004] The gas dispensing valve according to the invention, having the features of the independent claims, has the advantages of reducing the thermal load on the sealing seat and ensuring a reliable seal of the dispensing gas between individual injections and in the event of internal combustion engine shutdown. For this purpose, the gas dispensing valve has a housing in which a gas space is constructed, the gas space having an inlet and an outlet. A movable valve element is arranged in the gas space, the movable valve element being movable against the force of a return spring by an electric actuator, and the movable valve element cooperating with the sealing seat to open and close the inlet. A shut-off valve is arranged between the valve element and the outlet, the shut-off valve being capable of additionally interrupting the gas flow to the outlet.

[0005] To add gas to the combustion chamber, the valve element is opened by an electric actuator, such as an electromagnet. Gas flowing in through the inlet is pressurized ahead of the shut-off valve, which opens the shut-off valve. The gas passes through the shut-off valve and eventually reaches the combustion chamber. Combustion in the combustion chamber is ignited during the gas addition and thus the valve element's closure, or shortly afterward, with the flame front also spreading towards the gas dispensing valve. However, because the shut-off valve closes directly after the gas dispensing valve's inlet, the flame front in the combustion chamber can only spread to the shut-off valve, effectively protecting the valve element's sealing seat. The sudden pressure increase due to combustion in the combustion chamber also supports the closure of the shut-off valve. Because the valve seat is protected from high temperatures, resilient seals, such as elastomeric seals, can be used there, which is particularly advantageous in the case of hydrogen.

[0006] In an advantageous first configuration of the invention, the shut-off valve includes a movable shut-off element loaded by a shut-off spring, which is preferably guided longitudinally within the gas space. Thus, a shut-off valve is achieved without additional components, especially electrical components, which effectively allows gas flow only in the desired flow direction and therefore functions as a check valve. Here, the shut-off element can be constructed in a disc shape, which on the one hand is a simple and easy-to-manufacture shape, and on the other hand, in longitudinal movement perpendicular to the disc plane, has been adjusted to a large flow cross-section even with a short stroke. This allows the unavoidable throttling on the shut-off valve to be kept small, so as to provide full gas pressure when gaseous fuel is introduced. Advantageously, a return spring that loads the valve element in the shut-off direction can also be provided, with its other end supported on the shut-off element.

[0007] In another advantageous configuration of the invention, a pressure pin is constructed on the valve element, which, during the opening movement of the valve element, abuts against the closing element and thus applies an opening force to the closing element, i.e., opens the shut-off valve. In this embodiment, the shut-off valve is opened not only by the pressure difference between the front and rear of the closing element, but also by the movement of the valve element. This shortens the response time of the gas dispensing valve, i.e., the time elapsed between the activation of the electro-actuator and the actual outflow of gaseous fuel.

[0008] In another advantageous configuration, the valve element works in conjunction with the valve seat in the gas space to close the intake port. Here, a resilient sealing element is advantageously arranged on the valve sealing surface of the valve element or on the valve seat. The intake port can be tightly closed by the resilient sealing element, which is especially important when dispensing gaseous hydrogen, thus preventing undesirable leakage at the valve seat. In the case of hydrogen, it is very important for safety reasons that the valve seat is completely sealed when the engine is off. Hydrogen is also not allowed to accumulate outside the engine (where it would be ignited) during extended use, for example, in engines installed in commercial vehicles.

[0009] To further improve sealing, an engagement edge can be advantageously provided on the valve seat. This engagement edge increases the face pressure in this area, further improving the seal. Additionally, a surrounding annular ridge can be provided on the valve element. This annular ridge surrounds the engagement edge and is designed at a height such that during the closing movement of the valve element, the resilient sealing element first, followed by the annular ridge, abuts against the valve seat. Thus, the minimum distance between the valve sealing surface and the valve seat is defined by the annular ridge, preventing excessive load on the resilient sealing element.

[0010] In another advantageous configuration, the shut-off valve includes a valve needle, which serves as a closing element. This valve needle is longitudinally movable within the gas space and prevents backflow of gas into the gas space. Advantageously, a valve seat is constructed on the end of the valve needle facing the exhaust port, with the valve needle acting in conjunction with a corresponding sealing surface. Here, the valve needle is preferably preloaded in the direction of the sealing surface by a closing spring.

[0011] In another advantageous configuration, a pressure pin is constructed on the valve element, which abuts against the valve needle during the opening movement of the valve element, thereby applying an opening force to the valve needle. As in the embodiment with a disc-shaped closing element, the shut-off valve is opened together with the valve element. Attached Figure Description

[0012] Different embodiments of the invention are shown in the accompanying drawings. They illustrate:

[0013] Figure 1 A longitudinal section of a first embodiment of the gas dispensing valve according to the present invention.

[0014] Figure 2 In the enlarged illustration Figure 1 The part marked with II in the middle,

[0015] Figure 3 In another embodiment of the invention, a gas dispensing valve is shown only schematically.

[0016] Figure 4a 4b and 4c are also shown in the schematic diagram as another embodiment of the gas dispensing valve according to the invention, which has a needle-shaped shut-off element.

[0017] Figure 5 Another embodiment of the gas dispensing valve according to the invention in longitudinal section.

[0018] Figure 6 Another embodiment of the gas dispensing valve according to the present invention, and

[0019] Figure 7 exist Figure 6 The valve shown is a variant with an outwardly opening valve needle. Detailed Implementation

[0020] exist Figure 1 A first embodiment of the gas dispensing valve according to the present invention is shown in longitudinal section. The gas dispensing valve has a housing 1 in which a gas space 2 is constructed. The gas space 2 has an inlet 5 and an outlet 6, wherein the gas to be dispensed enters the gas dispensing valve through the inlet 5 and enters the combustion space of the internal combustion engine through the outlet 6. Here, the outlet 6 is constructed on the end of a nozzle tube 7 that deflects the gas flow so that the gas reaches the desired spatial region of the combustion space. A valve element 8 is longitudinally movably arranged in the gas space 2, the valve element having a valve sealing surface 10 on its end face facing the inlet opening 5, the valve sealing surface being constructed on a sealing element 9, which is part of the valve element 8. The valve element 8, with the valve sealing surface 10 acting in conjunction with a valve seat 11, closes the inlet 5, wherein, in this embodiment, the valve seat 11 is constructed in a connector 4, which is part of the housing 1 and has a longitudinal bore that forms the inlet 5.

[0021] To achieve a reliable seal for the air inlet 5, an elastic sealing portion 12 is provided on the valve sealing surface 10 of the valve element 8, such as... Figure 2 exist Figure 1As shown in the enlarged view of the portion marked II. Here, the resilient seal 12, such as an elastomer, covers the valve sealing surface 10 and works in conjunction with the engagement edge 13, which is constructed on the valve seat 11 and surrounds the inlet 5. The engagement edge 13 increases the surface pressure between the valve seat 11 and the resilient seal 12, thereby achieving an airtight seal even with highly volatile gases such as hydrogen. Furthermore, at the valve sealing surface 10, an annular ridge 14 is also constructed on the outer edge of the sealing element 9, wherein the annular ridge 14 surrounds the engagement edge and is designed at a height such that during the closing movement of the valve element 8 toward the valve seat 11, the resilient seal 12 first rests on the engagement edge 13, and then, with continued closing movement, the annular ridge 14 rests on the valve seat 11. Here, the height of the ring ridge 14 is greater than the height of the engagement edge 13, so that although the elastic sealing part 12 is pressed against the engagement edge 12 and thus effectively sealed, it will not be subjected to excessive mechanical load.

[0022] To enable the movement of valve element 8 within the gas dispensing valve, an electro-actuator in the form of an electromagnet 16 surrounds the housing 1 at the height of valve element 8 and is secured by a locking nut 3. Here, valve element 8 functions as a tauchanker for the electromagnet 16, such that when current is applied to the electromagnet 16, valve element 8 is pulled away from valve seat 11 until it abuts against the travel stop 20 in the gas space 2. The movement of valve element 8 occurs against the force of return spring 17, which preloads valve element 8 against valve seat 11 and also causes valve element 8 to move back to its closed position and lock the inlet 5 when the electromagnet 16 is turned off. To direct the gas flow from inlet 5 to outlet 6, a transverse bore 18 and an intersecting longitudinal bore 19 are constructed in valve element 8, designed such that no significant throttling of the gas flow occurs in this region.

[0023] A shut-off valve 25 is arranged between valve element 8 and exhaust port 6. In this embodiment, the shut-off valve only allows gas flow in the flow direction 15 from inlet 5 to exhaust port 6, while blocking gas flow in the opposite direction. The shut-off valve 25 includes a closing element 26, which is here in the form of a flat disc. The closing element 26 is pressed against a sealing surface 23 by a closing spring 29, which is constructed on a shoulder 22 arranged in the gas space 2. That is, the shut-off valve 25 opens only when the gas pressure between the closing element 26 and valve element 8 is greater than the gas pressure on the opposite side of the closing element 26 and is able to overcome the force of the closing spring 29. Because the closing element 26 is disc-shaped, it has a surrounding edge, so that the closing element has been adjusted to a relatively large flow cross-section with a small stroke, and the gas can flow to exhaust port 6 without significant throttling.

[0024] To add gaseous fuel to the combustion chamber, current is applied to the electromagnet 16, and the valve element 8 is pulled away from the valve seat 11 by the magnetic field generated therefrom until it rests against the travel stop 20. Gas then flows through the inlet 5 and the transverse and longitudinal bores 18 and 19 of the valve element 8 to the shut-off valve 25. Due to the increased pressure on the side of the shut-off element 26 facing the valve element 8, the valve element is squeezed against the force of the shut-off spring 29, opening the flow cross-section between the sealing surface 23 and the shut-off element. Gas flows through this cross-section into the nozzle cylinder 7 and eventually to the exhaust port 6. To end the gas injection, the current to the electromagnet 16 is interrupted, thus closing the inlet 5 again. Now, since no more gas flows to the shut-off valve 25, it is also closed by the shut-off spring 29.

[0025] The gas metering valve is particularly suitable for injecting gas into the combustion chamber of an internal combustion engine because it achieves a reliable gas seal while having a long service life. The valve element 8 and thus the resilient seal 12 are kept away from the combustion chamber by the nozzle cylinder 7, which limits the thermal load on the valve seat 11. Furthermore, the shut-off valve 25 prevents the flame front in the combustion chamber from spreading into the gas chamber 2, as the shut-off valve 25 closes immediately after gas injection, which is additionally supported by the increased pressure in the combustion chamber. Therefore, overheating of the valve seat 11 is reliably prevented.

[0026] exist Figure 3 Another embodiment of the gas dispensing valve according to the invention is shown in longitudinal section, wherein the illustration is only schematic. Figure 1The most important structural difference in the embodiment lies in the pressure pin 30 arranged on the valve element 8. During the opening movement of the valve element 8, the pressure pin 30 abuts against the closing element 26 and causes the closing element to move against the force of the closing spring 29 to its open position. Because the shut-off valve 25 therefore opens almost simultaneously with the valve element 8, there is no delay caused by the pressure build-up that would otherwise be required in front of the shut-off valve 25, resulting in a shorter response time, i.e., a shorter delay between the current flow to the electromagnet 16 and the start of gas injection. The closing process of this gas dispensing valve is similar to... Figure 1 The implementation is carried out in accordance with the examples.

[0027] exist Figure 4a Another embodiment of the gas dispensing valve according to the invention is shown in the figure, wherein the figure corresponds to Figure 3 The diagram is shown. For simplicity, valve element 8 and valve sealing surface 10 are only shown simplified, and instead of transverse borehole 18 and longitudinal borehole 19, two longitudinal boreholes 19 are constructed here; however, this is functionally equivalent. Here, the shut-off valve 25 has a closing element in the form of a valve needle 26'. The valve needle 26' is guided in the nozzle barrel 7 by a first guide section 32 and a second guide section 33, wherein an anschliffe (not shown) is constructed on the two guide sections 32, 33, which allows unthrottled gas flow passing beside the guide sections 32, 33. The valve needle 26' has a valve seat 35 at its end facing the exhaust port 6, and the valve needle 26' works in conjunction with the tapered sealing surface 23' at the end of the nozzle barrel 7. Here, the valve needle 26' is pressed against the sealing surface 23' by a closing spring 29, and—as in Figure 1 The shut-off element in the embodiment is the same as that in the example – it is opened by a corresponding pressure in the gas space 2. That is, the seal relative to the combustion space is made directly at the end of the gas dispensing valve, so that the flame front of the combustion space can only reach the outermost end of the housing 2.

[0028] Figure 4b A variation of this embodiment is shown. Here, the return spring 17 of the valve element 8 is not supported on the shoulder of the housing 2, but on the closing element or valve needle 23'. Because it is not necessary to provide a support surface for the return spring 17, greater structural freedom is created in the design of the housing 2.

[0029] Figure 4c Another embodiment according to the invention is shown. As in [the following]... Figure 3 In this embodiment, a pressure pin 30 is constructed on the valve element 8. During the opening movement of the valve element 8, the pressure pin abuts against the valve needle 26' and causes the valve needle to move in the opposite direction to the preload of the closing spring 29. Therefore, functionally, this produces a change in the relationship between the valve element 8 and the valve needle 26' as previously described. Figure 3 The same mutual cooperation is found in the embodiments.

[0030] exist Figure 5 Another embodiment of the gas dispensing valve according to the invention is shown. Here, the resilient sealing element 12 is achieved by a sealing ring on the valve seat 11, with the valve element 8 in its closed position abutting the valve sealing surface 10 against the valve seat. To allow gas to pass through the valve element, two or more inwardly extending inclined boreholes 19' are constructed, and a return spring 17 is received in a cylindrical groove in the valve element 8. The closing element 26 of the shut-off valve 25 is guided in a guide borehole 38 in the housing 1, wherein gas is guided through an inclined borehole 27 in the closing element 26. A sealing surface 23 is constructed on a surrounding annular ridge in the gas space 2, and the closing element 26 works in conjunction with the sealing surface.

[0031] Figure 6 Another embodiment of the gas dispensing valve according to the present invention is shown. Valve element 8 and in Figure 5 The illustrated embodiment is similarly constructed; however, downstream of valve element 8, the coupler sleeve 40 is longitudinally movably guided within the housing 1. A return spring 17, under pressure preload, is positioned between the coupler sleeve 40 and the housing 1, pressing the coupler sleeve 40 against the valve element 8 and squeezing it toward the valve seat 11. The coupler sleeve 40 internally forms a channel 43. With valve element 8 open, gas flows from the valve seat 11 through this channel via the inclined bore 19' and the central groove 39, and is further guided through this channel to the exhaust port 6.

[0032] A damping space 42 is constructed between the valve element 8 and the shoulder 41 in the housing 10, the damping space being inwardly confined by the coupler sleeve 40. The damping space 42 is connected to the gas space 2 via a first annular gap 44 between the valve element 8 and the housing 1 and a second annular gap between the coupler sleeve 40 and the housing, wherein the two annular gaps 44, 45 are designed such that gas flow from or into the damping space 42 can only occur in a throttling manner. The damping space 42 serves to suppress valve element movement by means that during the opening movement of the valve element 8 as it leaves the valve seat 11, gas is squeezed out of the damping space 42 and forced out through the annular gaps 44, 45. Because the gas can only flow out in a throttling manner, an overpressure is created in the damping space 42, which suppresses the opening movement of the valve element 8. During the closing movement, the volume of the damping space 42 increases and the pressure there decreases. This negative pressure causes the closing motion to be slowed down due to the back pressure (Gegendruck) on the opposite side of the valve element 8, so that the valve element 8 is damped and supported on the valve seat 11. This results in reduced wear between the valve sealing surface 10 and the valve element 11 and also results in less noise emissions.

[0033] To more accurately adjust the damping function, a gap 50 can be provided between the coupler sleeve 40 and the valve element 8, for example, in the form of one or more cutouts at the end of the coupler sleeve 40. The shape and number of gaps 50 allow for precise adjustment of the damping function without adjusting the annular gaps 44, 45. However, instead of or in addition to the gap 50, modifications to the annular gaps 44, 45 can be made, for example, by longitudinal grooves in the valve element 8 or on the outside of the coupler sleeve 40, to specifically affect the flow resistance through the annular gaps 44, 45 and thus the damping effect from the damping space 42 to the valve element 8.

[0034] Figure 7 In another embodiment shown Figure 6 Another embodiment of the gas dispensing valve shown is described. The coupler sleeve 40, with its end face away from the valve element 8, rests against the needle-shaped closing element 26', thereby moving the coupler sleeve 42 toward the exhaust port 6 by the movement of the valve element 8 from the valve seat 11 in the opening direction, and the coupler sleeve then opens the valve needle 26'. Gas flow from the passage 43 to the exhaust port 6 is ensured by multiple openings 48 in the coupler sleeve 42. Here, the valve needle 26' is also preloaded toward the tapered valve seat 35 by a closing spring 29, which, under pressure preload, is arranged between a disc spring 31 connected to the valve needle 26' and a shoulder in the housing 1. Grinding discs (not shown in the figures) are also constructed on the two guide sections 31, 32, ensuring unrestricted gas flow to the exhaust port 6.

[0035] Although the gas metering valve is particularly suitable for metered release of gas into the combustion chamber, it can also be used for other purposes, such as metered release of gas into the intake manifold of an internal combustion engine or for other technical applications.

Claims

1. A gas dispensing valve for an internal combustion engine, comprising a housing (1) in which a gas space (2) is constructed, the gas space having an inlet (5) and an outlet (6), and the gas dispensing valve having a valve element (8) movably arranged in the gas space (2), the valve element being movable by an electric actuator (16) against the force of a return spring (17), and the valve element cooperating with a valve seat (11) to open and close the inlet (5), characterized in that, A shut-off valve (25) is arranged between the valve element (8) and the exhaust port (6), which is capable of interrupting the gas flow in the gas space (2) between the valve element (8) and the exhaust port (6). Downstream of the valve element (8), a coupler sleeve (40) is longitudinally guided inside the housing (1). A return spring (17) is arranged between the coupler sleeve (40) and the housing (1) under pressure preload and presses the coupler sleeve (40) against the valve element (8) and towards... The valve seat (11) presses the valve element in the direction of the valve element (8) and the shoulder (41) in the housing (1) to form an annular damping space (42), the damping space (42) being connected to the gas space (2) through a first annular gap (44) between the valve element (8) and the housing (1) and / or through a second annular gap (45) between the coupler sleeve (40) and the housing (1), wherein the first annular gap (44) and the second annular gap (45) function as throttling gaps.

2. The gas dispensing valve according to claim 1, characterized in that, The shut-off valve (25) includes a movable shut-off element (26) loaded by a shut-off spring (29).

3. The gas dispensing valve according to claim 1 or 2, characterized in that, The shut-off valve (25) opens in the flow direction (15) toward the exhaust port (6) and shuts off in the opposite flow direction.

4. The gas dispensing valve according to claim 2, characterized in that, The closing element (26) is disc-shaped and is pressed by the closing spring (29) against the sealing surface (23) constructed in the gas space (2).

5. The gas dispensing valve according to claim 2 or 4, characterized in that, The return spring (17) is arranged between the valve element (8) and the closing element (26) under pressure preload.

6. The gas dispensing valve according to claim 1, characterized in that, A valve sealing surface (10) is constructed on the valve element (8), and the valve element (8) works together with the valve seat (11) in the gas space (2) to lock the air inlet (5).

7. The gas dispensing valve according to claim 6, characterized in that, An elastic sealing element (12) is arranged on the valve sealing surface (10) or on the valve seat (11).

8. The gas dispensing valve according to claim 6 or 7, characterized in that, An engagement edge (13) is constructed on the valve seat (11).

9. The gas dispensing valve according to claim 7, characterized in that, An annular ridge (14) is constructed on the valve sealing surface (10), which abuts against the valve seat (11) in the closed position of the valve element (8), such that during the closing movement of the valve element (8), the elastic sealing element (12) abuts first and then the annular ridge (14) abuts against the valve seat (11).

10. The gas dispensing valve according to claim 1, characterized in that, The shut-off valve (25) includes a shut-off element in the form of a valve needle (26'), which is longitudinally movable and guided in the gas space (2).

11. The gas dispensing valve according to claim 10, characterized in that, The valve needle (26') has a tapered valve seat (35) on its end facing the exhaust port (6), and the valve needle (26') works together with the tapered valve seat and the tapered sealing surface (23') on the end of the nozzle cylinder (7).

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