GAS DOSER VALVE FOR THE DOSED RELEASE OF GAS-FORMED FUEL

Description

[0001] The invention relates to a gas metering valve as used for the metered release of gaseous fuel, in particular for introducing gaseous fuel into a combustion chamber of an internal combustion engine State of the art

[0002] Gas metering valves are known from the prior art in which gaseous fuel can be metered and released at short intervals directly into the combustion chamber of an internal combustion engine or into the intake tract of an internal combustion engine. Various gaseous fuels can be metered in this way, in particular hydrogen. The metered release of hydrogen places special demands on the metering valve. Firstly, hydrogen is chemically very reactive, which requires correspondingly resistant materials. Secondly, due to the small H2 molecules, hydrogen diffuses through very small gaps and is therefore difficult to seal completely. A purely metallic seal is therefore usually not sufficient to completely seal out hydrogen, so the use of elastic materials such as elastomers such as plastics or rubber is necessary.

[0003] Gas metering valves that release hydrogen directly into the combustion chamber of an internal combustion engine are exposed to the high temperatures in the combustion chamber at their combustion-chamber end and must therefore be heat-resistant. The use of an elastomer on a combustion-chamber-side valve seat is therefore ruled out, as elastomers cannot withstand such temperatures over the long term. To solve this problem, a gas metering valve is known from DE 10 2020 201 973 A1. The valve has two valve elements, the first valve element controlling an inlet opening of the metering valve, while the second valve element opens and closes the combustion-chamber-side outlet opening. Only the first valve element, which is located far away from the combustion chamber, is equipped with an elastomer seal to ensure complete sealing of the hydrogen, while the combustion chamber close to the sealing seat is designed as a metallic seal.When the gas dosing valve is closed, complete sealing is ensured, while the actual dosing, i.e. the brief opening and closing of the dosing valve, can also be carried out via the second valve element with the metallic seal.

[0004] US 10 036 352 B2 discloses a previously published gas metering valve for metered delivery of gaseous fuel.

[0005] Both valve elements are controlled by a single electromagnet that acts on the first valve element, with the first valve element driving the second valve element with it during its opening movement. Since the greatest possible distance between the two valve elements should be achieved, a coupler element that transmits the movement is provided between the first valve element and the second valve element, for example in the form of a coupler sleeve. All moving components are guided within the housing, although it must be noted that the gaseous fuel has no lubricating properties whatsoever and the guide gaps of the valve elements must therefore be relatively large to prevent the components in the housing from jamming or suffering excessive wear.Therefore, there is a risk that a possible misalignment of the first valve element, which also serves as a magnet armature, will be transferred to the other components, in particular to the coupler sleeve, so that increased wear occurs at certain points between the first valve element or the coupler sleeve on the one hand and the housing on the other. Advantages of the invention

[0006] The gas metering valve according to the invention has the advantage that the valve elements are guided precisely within the gas chamber without increased wear between the housing and the valve elements or the coupler sleeve, and at the same time the assembly of the gas metering valve is not impaired. For this purpose, the gas metering valve has a housing in which a gas chamber with an inlet opening and an outlet opening is formed. A valve element is arranged in the gas chamber so as to be longitudinally movable, which opens and closes the inlet opening through its longitudinal movement, wherein the valve element is movable by an electric actuator. Furthermore, a nozzle needle is arranged in the gas chamber, which interacts with a nozzle seat to open and close the outlet opening, wherein a coupler sleeve is arranged between the valve element and the nozzle needle, which transmits the movement of the valve element to the nozzle needle.The coupler sleeve is accommodated in a receiving opening of the valve element without any play.

[0007] The movement of the valve element, which interacts with the electric actuator, is transmitted to the nozzle needle via the coupler sleeve. Because the coupler sleeve is held in the receiving opening with zero play, the valve element and the coupler sleeve stabilize each other, preventing misalignment of the two components within the housing. Nevertheless, the gas metering valve is easy to assemble, as both components can be manufactured separately and are only plugged together and thus firmly connected during assembly.

[0008] In an advantageous embodiment of the invention, the gas flow is guided from the inlet opening to the outlet opening through the coupler sleeve. This results in considerable design freedom in guiding the coupler sleeve and thus in optimizing the force transmission from the valve element to the nozzle needle. The coupler sleeve is advantageously designed as a hollow cylinder, and the receiving opening on the valve element is designed as a blind bore. To enable a secure connection between the two components, the outer diameter of the section of the coupler sleeve that is arranged within the receiving opening is 1 to 10 µm larger than the inner diameter of the receiving opening in the unassembled state in order to form a secure connection over the service life of the metering valve.

[0009] In a further advantageous embodiment, the coupler sleeve has a first sleeve section and a second sleeve section, wherein the first sleeve section is made of a ferromagnetic material and is received in the receiving opening of the valve element, while the second sleeve section is made of a non-ferromagnetic material, wherein both sleeve sections are firmly connected to one another. Since the first valve element serves as a magnet armature when the electrical actuator is designed as an electromagnet, a ferromagnetic coupler sleeve amplifies the effect of the electromagnet on the magnet armature, i.e. the first valve element. However, if the entire coupler sleeve is made of ferromagnetic material, the magnetic field is scattered too strongly, so that the effective magnetic force on the valve element is reduced.Since only the sleeve section located inside the valve element is ferromagnetic, this results in an increase in the magnetic force without generating a stray field, which directs the magnetic field into undesired areas of the housing.

[0010] Advantageously, the two sleeve sections are made of metallic materials and the fixed connection is realized by a welded joint, so that both sleeve sections are firmly and permanently connected to each other.

[0011] In a further advantageous embodiment, the coupler sleeve is guided laterally in the gas chamber along two axially spaced guide sections. Since there is a firm connection to the valve element, the valve element can also be guided through the coupler sleeve if a sufficiently large gap is formed between the outer wall of the valve element and the housing or the wall of the gas chamber. This eliminates friction and thus excessive wear between the valve element and the wall of the gas chamber. drawing

[0012] The drawing shows various embodiments of the gas metering valve according to the invention. It shows: Figure 1 shows a longitudinal section through a first embodiment of a gas metering valve according to the invention, Figure 2 shows an enlarged view of the Figure 1in the area of ​​the coupler sleeve and Figure 3 shows a further embodiment of the gas metering valve according to the invention in the same representation as Figure 2 . Description of the embodiments

[0013] In Figure 1 A gas metering valve according to the invention is shown in longitudinal section. The gas metering valve has a housing 1, which comprises a holding body 2, a magnetic body 3, a nozzle body 4 and a connecting body 5, which are clamped against one another in a gas-tight manner by means of a clamping nut 6 and further clamping elements not shown in the drawing. In the connecting body 5 there is a connection (not shown in the drawing), via which the gaseous fuel is guided into a gas chamber 8, which is formed in the holding body 2, the magnetic body 3 and the nozzle body 4. The gas chamber 8 has an inlet opening 9 and an outlet opening 10, wherein the inlet opening 9 in the drawing of the Figure 1is formed at the upper end of the gas metering valve, while the outlet opening 10 is shown at the lower end. A valve element 12 is arranged in the gas chamber 8 so as to be longitudinally displaceable. The valve element 12 has a sealing surface 16 with which the valve element 12 interacts with a valve seat 15 to open and close the inlet opening 9, wherein an elastomer is applied to the sealing surface 16 in order to close the inlet opening 9 in a gas-tight manner with respect to the gas chamber 8. A plurality of inclined bores 13 are formed in the valve element 12, through which gaseous fuel can flow into a receiving opening 14 which is designed as a blind bore. The valve element 12 is guided in a first guide section 17 in the gas chamber 8, wherein the first guide section 17 comprises, for example, a hardened sleeve which reduces the friction between the valve element 12 and the wall of the gas chamber 8.

[0014] A coupler sleeve 20, designed as a hollow cylinder, is received in the receiving opening 14. The coupler sleeve 20 has several openings 21 at its outlet end through which the gaseous fuel can escape and flow further toward the outlet opening 10. The outer diameter of the coupler sleeve 20 is dimensioned such that it fits into the receiving opening 14 without any play, thus forming a secure connection between the valve element 12 and the coupler sleeve 20.The coupler sleeve 20 is surrounded by a coupler spring 22, which is supported at one end on a support ring 23 that is fastened to the coupler sleeve 20 or is formed integrally therewith, and which is supported at the other end on a spring support ring 25 that is supported on the nozzle body 4 via a support element 26, so that a force is exerted on the coupler sleeve 20 and thus also on the valve element 12 in the direction of the inlet opening 9 via the prestressed coupler spring 22.

[0015] An electromagnet 18, which is arranged in the magnet body 3 and surrounds the valve element 12, serves to move the valve element 12. In order to optimally shape the magnetic field of the electromagnet 18, the holding body 2 has a thin turn 19, i.e., a tapered section in the holding body 2, so that the magnetic force on the valve element 12 is optimized. The coupler sleeve 20 is guided in a second guide section 24 within the housing, so that the combination of valve element 12 and coupler sleeve 20 is guided via the first guide section 17 and the second guide section 24. This ensures low-friction movement of the valve element 12 and coupler sleeve 20.

[0016] A nozzle needle 30, which comprises a shaft 31 and a valve plate 32, is also arranged in the nozzle body 4 and is longitudinally displaceable. A sealing surface 36 is formed on the valve plate 32, with which the valve plate 32 interacts with a nozzle seat 37 to open and close the outlet opening 10. The nozzle needle 30 is surrounded by a nozzle spring 33, which rests at one end on a shoulder 34 in the gas chamber 8 and at the other end on a spring plate 35, which is firmly connected to the nozzle needle 30. This results in a longitudinal force on the nozzle needle 31 in the direction of the inlet opening 9 via the pre-tensioned nozzle spring 33. In the closed state of the gas metering valve, in which the valve element 12 sits on the valve seat 15 and the nozzle needle 31 on the nozzle seat 37, the coupler sleeve 20 and the nozzle needle 30 are spaced apart from one another, ie a distance h is formed between the outlet-side end of the coupler sleeve 20 and the end face of the nozzle needle 30.This distance serves to compensate for thermal expansion, which is unavoidable during operation of the gas dosing valve.

[0017] The gas metering valve functions as follows: By energizing the electromagnet 18, the valve element 12 is pulled away from the valve seat 15, so that the inlet opening 9 is opened and gaseous fuel flows into the gas chamber 8. The gaseous fuel reaches the receiving opening 14 via the transverse bores 13 and thus into the coupler sleeve 20, from where the gaseous fuel flows further towards the outlet opening 10. The movement of the valve element 12 also moves the coupler sleeve 20 towards the outlet opening 10 until it comes into contact with the nozzle needle 30. The further movement of the coupler sleeve 20 or the valve element 12 pushes the nozzle needle 30 outwards, so that a flow cross-section is opened at the outlet opening 10, through which the gaseous fuel can flow out.To terminate the gas metering, the electromagnet 18 is switched off so that the coupler spring 22 and the nozzle spring 33 push the coupler sleeve 20 and thus the valve element 12 or the nozzle needle 30 back into their initial position.

[0018] In Figure 2A further embodiment of the gas metering valve according to the invention is shown in an enlarged view of the coupler sleeve 20. The coupler sleeve 20 here comprises a first sleeve section 120 and a second section 220, wherein the first sleeve section 120 is arranged within the receiving opening 14. The first sleeve section 120 is made of a ferromagnetic material, while the second sleeve section 220 is made of a non-magnetic material. Both sleeve sections 120, 220 are firmly connected to one another via a welded connection 28. Since the first sleeve section is ferromagnetic and firmly connected to the valve element 12, a stronger magnetic force is exerted on the valve element 12, thus enabling faster movement of the valve element 12.If the entire coupler sleeve 22 were made of a ferromagnetic material, the magnetic field of the electromagnet 18 would be scattered and thus the effective magnetic force on the valve element 12 would be reduced.

[0019] Figure 3shows a further embodiment of the gas metering valve according to the invention. Here, the assembly of valve element 12 and coupler sleeve 20 is no longer guided via a first guide section on the valve element 12, but rather via a first guide section 17' of a coupler sleeve, so that the entire guidance of the assembly of valve element 12 and coupler sleeve 20 is carried out via the coupler sleeve 20. The two guide sections 17' and 24 on the coupler sleeve ensure guidance of the valve element 12, which has correspondingly large gaps between its outer side and the wall of the gas chamber, so that contact and thus wear between the valve element 12 and the wall of the gas chamber 8 does not occur. To illustrate the magnetic field, which is guided via the thin turn 19 and the magnetic first sleeve section 120, Figure 3on the right side the magnetic field lines 27 of the electromagnet 18 and their approximate course within the gas dosing valve.

Claims

1. Gas-metering valve for metered dispensing of gaseous fuel, having a housing (1) in which a gas space (8) with an inlet opening (9) and an outlet opening (10) is formed, wherein a valve element (12) is arranged in a longitudinally movable manner in the gas space (8), said valve element opening and closing the inlet opening (9) by way of its longitudinal movement, wherein the valve element (12) has a sealing surface (16) by way of which the valve element (12) interacts with a valve seat (15), wherein an elastomer is applied to the sealing surface (16) in order for the inlet opening (9) to be closed off in a gas-tight manner in relation to the gas space (8), and wherein the valve element (12) is able to be moved by an electrical actuator (18), and having a nozzle needle (30) which is arranged in the gas space (8) and interacts with a nozzle seat (37) for opening and closing the outlet opening (10), wherein a coupling sleeve (20) is arranged between the valve element (12) and the nozzle needle (30), said coupling sleeve transmitting the longitudinal movement of the valve element (12) to the nozzle needle (30), characterized in that the coupling sleeve (20) is received without play in a receiving opening (14) of the valve element (12).

2. Gas-metering valve according to Claim 1, characterized in that the gas stream from the inlet opening (9) to the outlet opening (10) is conducted through the coupling sleeve (20).

3. Gas-metering valve according to Claim 1 or 2, characterized in that the coupling sleeve (20) is in the form of a hollow cylinder, and the receiving opening (14) in the valve element (12) is a blind bore.

4. Gas-metering valve according to Claim 3, characterized in that, in the unfitted state, the inner diameter of the receiving opening (14) is 1 to 10 µm smaller than the outer diameter of that portion of the coupling sleeve (20) which is arranged within the receiving opening (14).

5. Gas-metering valve according to one of Claims 1 to 4, characterized in that the coupling sleeve (20) comprises a first sleeve portion (120) and a second sleeve portion (220), wherein the first sleeve portion (120) is made of a ferromagnetic material and is received in the receiving opening (14) of the valve element (20), and the second sleeve portion (220) is made of a non-ferromagnetic material, wherein both sleeve portions (120; 220) are connected fixedly to one another.

6. Gas-metering valve according to Claim 5, characterized in that the two sleeve portions (120; 220) are made of metallic materials and are welded to one another.

7. Gas-metering valve according to one of Claims 1 to 6, characterized in that the coupling sleeve (20) is guided laterally in the gas space (8) at at least two guide portions (17'; 24) spaced apart axially from one another.

8. Gas-metering valve according to Claim 7, characterized in that, laterally, the valve element (12) has guidance play of such a magnitude that it is guided in the radial direction exclusively by way of the coupling sleeve (20).

9. Gas-metering valve according to one of Claims 1 to 8, characterized in that the electrical actuator is an electromagnet (18), and the valve element (12) is in the form of a plunger-type armature.