Gas metering valve for internal combustion engines

Abstract

A gas metering valve for gaseous fuel, having a housing (1) in which an inlet opening (7) and an outlet opening (8) for gaseous fuel are configured. In the housing (1) a gas chamber (5) is configured and connects the inlet opening (7) with the outlet opening (8) in such a way that a gas flow from the inlet opening (7) to the outlet opening (8) can be realized. In the gas chamber (5) an electrically operable shut-off valve (10) is arranged in order to interrupt the gas flow in the gas chamber (5), and between the shut-off valve (10) and the outlet opening (8) an electrically operable control valve (25) is arranged with which the gas flow between the shut-off valve (10) and the outlet opening (8) can be interrupted.

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 or intake manifold of an internal combustion engine. Background Technology

[0002] For example, a gas valve for gas dispensing is known in the prior art, such as DE 10 2014 225 922 A1. The gas valve disclosed herein includes a movable valve element that can be moved by an electromagnet against a spring element, thereby opening and closing the connection between the inlet and outlet of the gas dispensing valve. By turning the electromagnet on and off, the gas to be dispensed can be dispensed at the desired time and in the desired quantity. The sealing seat of the gas valve is close to the outlet, which on the one hand enables a relatively compact structure, and on the other hand simplifies the precise control of the gas quantity.

[0003] When directly dispensing gaseous fuel into the combustion chamber of an internal combustion engine, the gas dispensing valve must be positioned close to the combustion chamber. Due to the high combustion temperatures, this causes the gas dispensing valve to overheat significantly. For example, when dispensing hydrogen, a reliable seal can only be achieved with difficulty using a metal sealing seat, especially since such a seal is essential for safety reasons throughout the entire service life of the gas dispensing valve, even if the internal combustion engine is not used for extended periods. Therefore, it is necessary to use plastic or elastomeric seals, but these seals cannot be exposed to high temperatures without damage. To limit the temperature on the sealing seat, the gas dispensing valve can be constructed such that the elastomeric-coated sealing seat is relatively far from the outlet and therefore far from the combustion chamber. However, this makes the gas dispensing valve more susceptible to flame flashback from the combustion chamber into the gas dispensing valve, because even when the gas dispensing valve is closed, its relatively large volume remains directly connected to the combustion chamber due to the distance of the sealing seat from the combustion chamber. Especially when the residue of combustible gas is located in the gas metering valve, the flame front of the combustion chamber will propagate into the gas metering valve, causing a strong thermal load at the sealing seat there. In addition, the sealing seat, located far from the outlet of the gas metering valve, makes precise metering of gaseous fuel difficult because the volume between the sealing seat and the outlet is relatively large. Summary of the Invention

[0004] In contrast, the gas dispensing valve according to the present invention has the advantages of reliably dispensing gaseous fuel, and its sealing performance is not affected even during long downtime. To this end, the gas dispensing valve has a housing in which an inlet and an outlet for gaseous fuel are constructed. A gas chamber is constructed within the housing, connecting the inlet and outlet to allow gas flow from the inlet to the outlet. An electrically operated shut-off valve is arranged in the gas chamber to interrupt the gas flow. An electrically operated control valve is arranged between the shut-off valve and the outlet, which can additionally interrupt the gas flow between the shut-off valve and the outlet.

[0005] Therefore, the gas metering valve includes two electrically controllable valves that can interrupt gas flow within the housing. After gas metering is complete, the control valve, specifically the one closer to the outlet and thus closer to the combustion chamber, can be closed to prevent heat intrusion. This significantly reduces the thermal load on the shut-off valve, allowing for the uninterrupted use of elastomeric seals, ensuring the desired seal even during extended periods of engine and gas metering valve downtime.

[0006] In an advantageous configuration, the shut-off valve includes a shut-off valve element that works in conjunction with a corresponding shut-off valve seat to interrupt gas flow within the gas chamber. The control valve also advantageously includes a movable control valve element that works in conjunction with a control valve seat to interrupt gas flow; wherein both valves are preferably configured as solenoid valves.

[0007] The shut-off valve seat and / or shut-off valve element are preferably coated with plastic, preferably an elastomer, to achieve a gaseous seal even when the amount of hydrogen dispensed is not practically completely sealed by a pure metal-to-metal seal. However, a complete seal is not necessary between each injection of gaseous fuel. If another injection is made at a shorter time interval, a certain degree of non-sealing can be tolerated because the small amount of gaseous fuel expelled is thus forced into the combustion chamber with the next injection, and the function of the internal combustion engine is not affected. Therefore, an elastomer coating on the control valve is unnecessary, and a robust and rigid material pairing can be chosen between the control valve element and the control valve seat to keep wear in this area as low as possible.

[0008] Since the two valves can preferably be switched independently of each other using their respective electromagnets, a method for operating the gas dispensing valve can be implemented. Here, it is preferable to open the shut-off valve before dispensing begins, while the control valve opens with a time delay. The metal-to-metal seal of the control valve is sufficiently tight to withstand brief interruptions in gas flow, allowing accurate and time-precise dispensing of gaseous fuel to be performed solely through the control valve, while the shut-off valve remains continuously open. During long standby times, i.e., when no gaseous fuel is dispensed for an extended period, the shut-off valve also closes to completely seal the gas dispensing valve. Attached Figure Description

[0009] Two embodiments of the gas dispensing valve according to the present invention are shown in the accompanying drawings. The drawings show:

[0010] Figure 1 The gas dispensing valve according to the invention is shown in longitudinal section, wherein only the main area is shown, and

[0011] Figure 2 With Figure 1 The same illustration shows another embodiment. Detailed Implementation

[0012] Figure 1The first gas dispensing valve according to the invention is shown in longitudinal section, wherein only the main components of the gas dispensing valve are shown. In particular, the connection lines and electrical connectors for supplying gaseous fuel are not shown. The gas dispensing valve includes a housing 1, which includes a valve body 2 and a nozzle body 3, which are hermetically clamped together by a clamping nut 4. A gas chamber 5 is constructed in the housing 1, which has an inlet 7 and an outlet 8, and thus allows gas to flow from the inlet 7 to the outlet 8. A shut-off valve 10 is arranged in the gas chamber 5, which is configured as a solenoid valve and includes a shut-off valve element 11, which can be moved by means of a first electromagnet 12 against a closing spring 17. The shut-off valve 10 is configured to interrupt the gas flow in the gas chamber 5 when the shut-off valve element 11 abuts against a shut-off valve seat 14. The shut-off valve seat 14 is thus constructed at the upper end of the gas chamber 5 in the figure and surrounds the inlet 7 through which gaseous fuel flows into the gas chamber 5. If the shut-off valve element 11 is abutting against the shut-off valve seat 14, the inlet 7 is closed relative to the gas chamber 5, so no gas can flow from the inlet 7 into the gas chamber 5. By energizing the electromagnet 12, the shut-off valve element 11 can be pulled away from the shut-off valve seat 14, thereby releasing a flow cross section between the shut-off valve element 11 and the housing 2, through which gas flows from the inlet into the gas chamber 5. Here, a further flow path is provided through two or more connecting holes 16, which are constructed in the shut-off valve element 11 and lead to an elongated orifice 18, which runs centrally in the shut-off valve element 11, in which the closing spring 17 is also arranged.

[0013] An electromagnet 12 surrounds the valve body 2 on the outside of the valve body, wherein the valve body 2 or a portion thereof serves as a magnetic core to selectively concentrate the magnetic field in the region of the shut-off valve element 11, thereby enabling rapid switching. A travel stop for the shut-off valve element 11 is provided by an intermediate disk 20 having a central opening 21 through which gas can further flow within the gas chamber 5. Here, the intermediate disk 20 is located on a shoulder within the gas chamber 5 and is fixedly held there by the preload of the closing spring 17.

[0014] On the shut-off valve element 11, an elastic seal 15 is arranged in the sealing surface area that interacts with the shut-off valve seat 14. This elastic seal is made of flexible plastic and can therefore be elastically adapted to the sealing surface. This elastic seal 15 is responsible for providing an airtight seal on the shut-off valve seat 14, even if the gas metering valve is not used for a long time and the gas is continuously pressed against the inlet at a preset injection pressure.

[0015] Downstream of the shut-off valve 10 and the intermediate disc 20, a control valve 25 is arranged in the gas chamber 5. Like the shut-off valve 10, this control valve can interrupt the gas flow towards the outlet 8 within the gas chamber 5. The control valve 25 includes a control valve element 26 comprising an electromagnetic armature 27 and a shut-off element 28, which are interconnected and therefore always move together. The electromagnetic armature 27 is substantially cylindrical and has two or more elongated orifices 35 through which gaseous fuel can flow towards the outlet 8, located at the end of the valve body 2, which forms the combustion chamber side end of the housing 1. The shut-off element 28 is piston-shaped and has a shut-off disc 28' at its combustion chamber side end, i.e., the lower end in the figures, on which a sealing surface is formed. This sealing surface interacts with a control valve seat 31, which is configured to surround the outlet 8 outside the nozzle body 3. The closing element 28 is surrounded by a spring 30, which, under pressure preload, is positioned between a shoulder 32 and a support plate 33 in the nozzle body 3, wherein the support plate 33 is fixedly connected to the closing element 28. The preload force of the spring 30 presses the control valve element 26 against the control valve seat 31, thus closing the air outlet 8.

[0016] To open control valve 25, electromagnet 29 is energized. This electromagnet, against the force of spring 30, pulls control valve element 26 from control valve seat 31 toward the combustion chamber, i.e., out of gas chamber 5. This controllably opens the flow cross-section between shut-off disc 28' and control valve seat 31, allowing gaseous fuel to flow out through this cross-section. After energizing electromagnet 29 ceases, spring 30 pushes control valve element 26 back into its closed position.

[0017] Another example is in Figure 2 The accompanying drawing shows that the figure is in conjunction with... Figure 1 The same diagram shows the shut-off valve element 11' and Figure 1 The first embodiment is compared to a gas dispensing valve arranged 180° rotated. Correspondingly, a pre-tensioned shut-off spring 17' is arranged between the inlet 7 and the shut-off valve element 11', pressing the shut-off valve element 11' against the shut-off valve seat 14', which is constructed on the central opening 21 of the intermediate disk 20. In this embodiment, an elastic seal 15' is also present, thus the shut-off valve element 11' hermetically closes the central opening 21.

[0018] According to Figure 2In this embodiment, the shut-off valve element 11' opens against the flow direction of the gaseous fuel by the action of the electromagnet 12. If an overpressure condition occurs, resulting in an unacceptably high gaseous fuel pressure differential between the inlet 7 and outlet 8, the gas flow assists the closing spring 17' and presses the shut-off valve element 11' into its closed position. This prevents uncontrolled release of gaseous fuel into the system to which it is to be supplied, such as the combustion chamber of an internal combustion engine.

[0019] The two electromagnets 12 and 29 can be operated independently of each other, allowing the shut-off valve 10 and the control valve 25 to open and close independently. Control valve 25 is sufficient to accurately dispense gaseous fuel into the combustion chamber, as a complete shut-off is typically not required between closely spaced injections. Therefore, the gas dispensing valve can operate such that shut-off valve 10 opens at the start of dispensing, followed by control valve 25, which determines the amount of gaseous fuel by its opening timing and duration. If further gaseous fuel release is desired, only control valve 25 can be closed and reopened, while shut-off valve 10 remains continuously open. Shut-off valve 10 is only closed for extended dispensing pauses to achieve the necessary absolute seal. Therefore, shut-off valve 10 does not need to be highly dynamic; that is, a relatively simple solenoid valve can be used, consisting only of small electromagnets and thus requiring minimal energy. Since control valve 25 does not need to meet high sealing requirements, a hard and low-wear material can be used in the area of ​​the control valve seat. This material can withstand high loads and has a long service life.

Claims

1. A gas metering valve for gaseous fuel, the gas metering valve having a housing (1) in which an inlet (7) and an outlet (8) for gaseous fuel are configured, and the gas metering valve having a gas chamber (5) configured in the housing (1) and the gas chamber connecting the inlet (7) and the outlet (8) to enable gas flow from the inlet (7) to the outlet (8), and the gas metering valve having a shut-off valve (10) controllable by an electric actuator for interrupting gas flow in the gas chamber (5), in, An electrically operated control valve (25) is arranged in the gas chamber between the shut-off valve (10) and the gas outlet (8). This control valve can interrupt the gas flow between the shut-off valve (10) and the gas outlet (8). The shut-off valve (10) and the control valve (25) are configured as electromagnetic control valves. The shut-off valve (10) is operated by a first electromagnet (12) and the control valve (25) is operated by a second electromagnet (29). The first electromagnet (12) and the second electromagnet (29) can be operated independently of each other, so that the shut-off valve (10) and the control valve (25) can be opened and closed independently of each other.

2. The gas dispensing valve according to claim 1, characterized in that, The shut-off valve (10) includes a movable shut-off valve element (11; 11') that works in conjunction with a shut-off valve seat (14; 14') to interrupt the flow of gas in the gas chamber (5).

3. The gas dispensing valve according to claim 2, characterized in that, The shut-off valve element (11; 11') is loaded with a closing force by the closing spring (17; 17') toward the shut-off valve seat (14; 14'), such that when the electric actuator is activated, the shut-off valve (10) moves against the force of the closing spring.

4. The gas dispensing valve according to claim 2, characterized in that, The shut-off valve (10) opens in the direction of the flow of the gaseous fuel.

5. The gas dispensing valve according to claim 2, characterized in that, The shut-off valve (10) opens against the flow direction of the gaseous fuel.

6. The gas dispensing valve according to any one of claims 2 to 5, characterized in that, The shut-off valve element (11; 11') is coated with plastic at least in the area where it interacts with the shut-off valve seat (14; 14'), and / or the shut-off valve seat (14; 14') is coated with plastic.

7. The gas dispensing valve according to any one of claims 1 to 5, characterized in that, The control valve (25) includes a movable control valve element (26) that works in conjunction with the control valve seat (31) to interrupt the flow of gas in the gas chamber (5).

8. The gas dispensing valve according to claim 6, characterized in that, The area and / or the shut-off valve seat (14; 14') are coated with an elastomer.

9. A method for operating a gas dispensing valve according to any one of claims 1 to 8, characterized in that, In order to dispense the gaseous fuel, the shut-off valve (10) is first opened and the control valve (25) is subsequently opened in time.

10. The method according to claim 9, characterized in that, During the operation of the gas dispensing valve, the shut-off valve (10) remains open and the dispensing of the gaseous fuel is achieved solely through the control valve (25).

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