Gas metering valve for metering the release of gaseous fuel

Abstract

The gas metering valve for metering and discharging a gaseous fuel has a housing (1) in which a gas chamber (8) with an inlet opening (9) and an outlet opening (10) is formed. A valve body (12) is longitudinally movable in the gas chamber (8) for opening and closing the inlet opening (9) by a longitudinal movement, the valve body (12) being movable by an electric actuator (18). A nozzle needle (30) is furthermore arranged in the gas chamber (8) which cooperates with a nozzle seat (37) for opening and closing the outlet opening (10). Between the valve body (12) and the nozzle needle (30) is arranged a coupler sleeve (20) for transmitting the longitudinal movement of the valve body (12) to the nozzle needle (30). The coupler sleeve (20) is received without clearance in the receiving opening (14) of the valve body (14).

Description

[Technical field]

[0001] The present invention relates to a gas metering valve adapted for the metered release of gaseous fuel, in particular for injecting gaseous fuel into the combustion chamber of an internal combustion engine. [Background technology]

[0002] Gas metering valves are known from the prior art, which can meter and release gaseous fuels after short time intervals directly into the combustion chamber of an internal combustion engine or into the intake manifold of an internal combustion engine. Various gaseous fuels can be metered in this way, including, in particular, hydrogen. The release of metered amounts of hydrogen places special demands on the metering valve, since on the one hand, hydrogen is chemically very reactive, which requires correspondingly durable materials. On the other hand, hydrogen, due to the small H2 molecules, diffuses through even very small gaps and is accordingly difficult to seal completely. Purely metallic seals are therefore often not sufficient to completely seal off hydrogen, so that the use of elastic materials, i.e. elastomers such as plastics or rubber, is required for sealing.

[0003] Gas metering valves which release hydrogen directly into the combustion chamber of an internal combustion engine are exposed at their end facing the combustion chamber to the high temperatures of the combustion chamber and must be correspondingly heat-resistant. The use of elastomers in the valve seat facing the combustion chamber is therefore not possible, since elastomers cannot withstand such temperatures permanently. To solve this problem, a gas metering valve is known from DE 10 200 63 33 A1, which has two valve bodies, a first valve body which controls the inlet opening of the metering valve, whereas a second valve body which opens and closes the outlet opening facing the combustion chamber. Only the first valve body, which is far from the combustion chamber, is equipped with an elastomer seal in order to ensure a complete sealing of the hydrogen, whereas the combustion chamber is configured as a metallic seal in the vicinity of the sealing seat. In this way, a complete seal is ensured when the gas metering valve is closed, whereas the actual metering, i.e. the temporary opening and closing of the metering valve, can also be performed via the second valve body with the metallic seal.

[0004] Both valve bodies are then controlled by a single electromagnet acting on the first valve body, which entrains the second valve body when it makes its opening movement. The widest possible distance between the two valve bodies should be achieved, so that between the first and second valve bodies there is a coupler element, for example in the form of a coupler sleeve, which transmits the movement. All moving components are guided inside the housing, but it must be noted that gaseous fuels do not have any lubricating properties and that the guide gaps of the valve bodies must be relatively wide in order to prevent components in the housing from getting stuck or wearing out excessively. There is therefore a risk that a possible tilting position of the first valve body, which also serves as a magnetic armature, will be transmitted to other components, especially to the coupler sleeve, which would result in too high wear at certain points between the first valve body or the coupler sleeve on the one hand and the housing on the other hand. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] German Patent Application Publication No. 102020201973A1 Summary of the Invention

[0006] In contrast, the gas metering valve according to the invention has the advantage that the valve body is guided precisely in the gas chamber, no increased wear occurs between the housing and the valve body or the coupling sleeve, and at the same time the assembling ability 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 body is longitudinally movable in the gas chamber, which opens and closes the inlet opening by a longitudinal movement, the valve body being movable by an electric actuator. In addition, a nozzle needle is arranged in the gas chamber, which cooperates with a nozzle seat to open and close the outlet opening, and a coupling sleeve is arranged between the valve body and the nozzle needle, which transmits the movement of the valve body to the nozzle needle. The coupling sleeve is then accommodated without clearance in the accommodation opening of the valve body.

[0007] The movement of the valve body, which cooperates with the electric actuator, is further transferred to the nozzle needle via the coupler sleeve. The coupler sleeve is accommodated without clearance in the accommodation opening, so that the valve body and the coupler sleeve are stabilized relative to one another, so that axial displacement of both components inside the housing is prevented. Nevertheless, the gas metering valve can be easily assembled, since both components can be produced separately and only fitted together during assembly, and thus fixedly connected.

[0008] In a preferred embodiment of the invention, the gas flow is guided from the inlet opening to the outlet opening through a coupler sleeve, which allows for a wide design freedom when guiding the coupler sleeve and thus optimizing the force transmission from the valve body to the nozzle needle. The coupler sleeve is then preferably designed as a hollow cylinder and the receiving opening of the valve body as a blind hole. In order to enable a fixed connection between both components, the outside diameter of the area of ​​the coupler sleeve that is arranged inside the receiving opening is 1 to 10 μm larger in the unassembled state than the inside diameter of the receiving opening in order to form a fixed connection throughout the service life of the metering valve.

[0009] In another preferred embodiment, the coupler sleeve has a first sleeve section and a second sleeve section, the first sleeve section being made of a ferromagnetic material and accommodated in the accommodation opening of the valve body, whereas the second sleeve section is made of a non-ferromagnetic material, and both sleeve sections are fixedly connected to each other. Since the first valve body serves as a magnetic armature when the electric actuator is configured as an electromagnet, the ferromagnetic coupler sleeve enhances the action of the electromagnet on the magnetic armature, i.e. on the first valve body. However, if the entire coupler sleeve were made of a ferromagnetic material, the magnetic field would be scattered too strongly, which would weaken the effective magnetic force on the valve body. Since only the sleeve section, which is arranged inside the valve body, is ferromagnetic, the magnetic force is enhanced without the associated generation of stray magnetic fields that would guide the magnetic field into undesired areas of the housing.

[0010] In this case, both sleeve sections are preferably made of metallic material and the fixed connection is realized by a welded connection, whereby the two sleeve sections are fixedly and permanently connected to one another.

[0011] In another preferred embodiment, the coupler sleeve is guided laterally in the gas chamber in two guide sections spaced apart from one another in the axial direction. Due to the fixed connection with the valve body, the valve body can also be guided by the coupler sleeve, provided that a correspondingly large gap is formed between the outer wall of the valve body and the wall of the housing or the gas chamber. As a result, friction and the associated excessive wear cannot occur between the valve body and the wall of the gas chamber.

[0012] The drawings show various embodiments of a gas metering valve according to the invention. [Brief description of the drawings]

[0013] [Figure 1] 1 is a vertical sectional view showing a first embodiment of a gas metering valve according to the present invention. [Diagram 2] FIG. 2 is an enlarged view of FIG. 1 showing the area of ​​the coupler sleeve. [Diagram 3] 3 is a view similar to FIG. 2 showing another embodiment of a gas metering valve according to the invention; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] In FIG. 1, a gas metering valve according to the invention is shown in a longitudinal section. The gas metering valve has a housing 1, which includes a holder 2, a magnet body 3, a nozzle body 4 and a connecting body 5, which are tension-fixed gas-tight to one another by means of a clamping nut 6 and further clamping elements not shown in the drawing. The connecting body 5 has a connection, not shown in the drawing, via which gaseous fuel is introduced into a gas chamber 8 formed in the holder 2, the magnet body 3 and the nozzle body 4. The gas chamber 8 here has an inlet opening 9 and an outlet opening 10, the inlet opening 9 being formed in the drawing in FIG. 1 at the upper end of the gas metering valve, whereas the outlet opening 10 is shown at the lower end. A valve body 12 is arranged in the gas chamber 8 so as to be able to slide longitudinally. The valve body 12 here has a sealing surface 16, with which the valve body 12 cooperates with a valve seat 15 to open and close the inlet opening 9, and on which an elastomer is attached in order to close the inlet opening 9 gas-tightly from the gas chamber 8. The valve body 12 is formed with a number of oblique holes 13, via which the gaseous fuel can flow into a receiving opening 14 configured as a blind hole. The valve body 12 is guided in the gas chamber 8 by a first guide section 17, which in this case includes, by way of example, a hardened sleeve that reduces friction between the valve body 12 and the wall of the gas chamber 8.

[0015] A coupler sleeve 20, which is configured as a hollow cylinder, is received in the receiving opening 14. At its outlet end, the coupler sleeve 20 has a number of openings 21, through which the gaseous fuel can escape and then flow in the direction of the outlet opening 10. The outer diameter of the coupler sleeve 20 is designed so that it is received without any clearance in the receiving opening 14, so that a fixed connection is formed between the valve body 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 attached to the coupler sleeve 20 or configured integrally therewith, and at the other end on a spring support ring 25 supported by a support element 26 on the nozzle body 4, so that a force is exerted on the coupler sleeve 20 and thus also on the valve body 12 in the direction of the inlet opening 9 via the prestressed coupler spring 22.

[0016] The valve disc 12 is moved by an electromagnet 18, which is arranged in the magnet body 3 and surrounds the valve disc 12. To best shape the magnetic field of the electromagnet 18, the holder body 2 has a thin-walled turning 19, i.e. a tapered section of the holder body 2, whereby the magnetic force on the valve disc 12 is optimized. The coupler sleeve 20 is guided inside the housing in a second guiding section 24, so that the combination of the valve disc 12 and the coupler sleeve 20 is guided via the first guiding section 17 and the second guiding section 24. A low-friction movement of the valve disc 12 and the coupler sleeve 20 is thereby ensured.

[0017] In the nozzle body 4, a nozzle needle 30 including a shaft 31 and a valve disk 32 is arranged, which can also slide longitudinally. A sealing surface 36 is formed on the valve disk 32, with which the valve disk 32 cooperates by means of a nozzle seat 37 for opening and closing the outlet opening 10. The nozzle needle 30 is surrounded by a nozzle spring 33 which is supported at one end on a step 34 in the gas chamber 8 and at the other end on a disk spring 35 which is fixedly connected to the nozzle needle 30. A longitudinal force is thus exerted on the nozzle needle 31 in the direction of the inlet opening 9 via the prestressed nozzle spring 33. In the closed state of the gas metering valve, with the valve body 12 resting on the valve seat 15 and the nozzle needle 31 resting on the nozzle seat 37, the coupler sleeve 20 and the nozzle needle 30 are spaced apart from each other, i.e. a distance h exists between the outlet end of the coupler sleeve 20 and the end face of the nozzle needle 30. This spacing serves to compensate for the thermal expansion that is unavoidable during operation of the gas metering valve.

[0018] The function of the gas metering valve is as follows: when the electromagnet 18 is energized, the valve body 12 is pulled away from the valve seat 15, so that the inlet opening 9 is freed and the gaseous fuel flows into the gas chamber 8. Via the cross bore 13, the gaseous fuel reaches the receiving opening 14 and flows therewith into the coupler sleeve 20, from where it flows further in the direction of the outlet opening 10. As a result of the movement of the valve body 12, the coupler sleeve 20 also moves in the direction of the outlet opening 10 until it abuts against the nozzle needle 30. With the further movement of the coupler sleeve 20 or the valve body 12, the nozzle needle 30 is pressed outwards, so that the flow cross section at the outlet opening 10 is enlarged, 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 press the coupler sleeve 20 and thus the valve body 12 or the nozzle needle 30 back into their initial positions.

[0019] FIG. 2 shows a further embodiment of a gas metering valve according to the invention in an enlarged view of the coupler sleeve 20. The coupler sleeve 20 here comprises a first sleeve section 120 and a second sleeve section 220, the first sleeve section 120 being arranged inside the receiving opening 14. The first sleeve section 120 is made of a ferromagnetic material, whereas the second sleeve section 220 is made of a non-magnetic material. The two sleeve sections 120, 220 are here fixedly connected to one another via a welded connection 28. The first sleeve section is ferromagnetic and is fixedly connected to the valve body 12, so that a stronger magnetic force is generated on the valve body 12 and thus a faster movement of the valve body 12 is possible. If the coupler sleeve 22 were entirely made of a ferromagnetic material, the magnetic field of the electromagnet 18 would be scattered and the effective magnetic force on the valve body 12 would be weakened accordingly.

[0020] 3 shows yet another embodiment of the gas metering valve according to the invention. Here, the valve body 12 and coupler sleeve 20 complex is not guided via the first guide section of the valve body 12, but via the first guide section 17' of the coupler sleeve, so that the entire guidance of the valve body 12 and coupler sleeve 20 complex is via the coupler sleeve 20. Both guide sections 17' and 24 of the coupler sleeve serve to guide the valve body 12 with a correspondingly large gap between the outer surface of the valve body and the wall of the gas chamber, so that contact and the associated wear between the valve body 12 and the wall of the gas chamber 8 does not occur. To illustrate the magnetic field through the thin-walled turning 19 and the magnetic first sleeve section 120, FIG. 3 shows on the right side the magnetic flux lines 27 of the electromagnet 18 and their approximate path inside the gas metering valve. [Explanation of symbols]

[0021] 1. Housing 8. Gas Chambers 9 Inlet opening 10 Outlet opening 12 Valve body 14 Storage opening 17 First Guidance Area 17' First guide area of ​​coupler sleeve 18 Electric actuator 20 Coupler sleeve 24 Second Guidance Area 30 Nozzle needle 37 Nozzle seat 120 First Sleeve Section 220 Second Sleeve Section

Claims

1. A gas metering valve for metering and discharging a gaseous fuel, comprising a housing (1) in which a gas chamber (8) is formed with an inlet opening (9) and an outlet opening (10), a valve body (12) is arranged in the gas chamber (8) so as to be longitudinally movable, the valve body (12) being movable by an electric actuator (18) and comprising a nozzle needle (30) arranged in the gas chamber (8) and cooperating with a nozzle seat (37) for opening and closing the outlet opening (10), and a coupler sleeve (20) is arranged between the valve body (12) and the nozzle needle (30) for transmitting the longitudinal movement of the valve body (12) to the nozzle needle (30), The coupler sleeve (20) is accommodated without clearance in the accommodation opening (14) of the valve body (12); 1. A gas metering valve, comprising: a coupler sleeve (20) having a first sleeve section (120) and a second sleeve section (220), the first sleeve section (120) being made of a ferromagnetic material and being accommodated in the accommodation opening (14) of the valve body (20), the second sleeve section (220) being made of a non-ferromagnetic material, and both sleeve sections (120; 220) being fixedly connected to each other.

2. 2. A gas metering valve as claimed in claim 1, characterized in that the coupler sleeve (20) is received in the receiving opening (14).

3. 2. A gas metering valve as claimed in claim 1, characterized in that the gas flow is guided from the inlet opening (9) to the outlet opening (10) through the coupler sleeve (20).

4. 4. A gas metering valve according to claim 1, 2 or 3, characterized in that the coupler sleeve (20) is designed as a hollow cylinder and the receiving opening (14) of the valve body (12) is a blind hole.

5. 5. The gas metering valve according to claim 4, characterized in that the inner diameter of the receiving opening (14) is smaller by 1 to 10 μm than the outer diameter of the area of ​​the coupler sleeve (20) that is arranged inside the receiving opening (14) in the unassembled state.

6. 6. Gas metering valve according to claim 1, characterized in that both sleeve sections (120; 220) are made of metallic material and are welded to one another.

7. 7. Gas metering valve according to claim 1, characterized in that the coupler sleeve (20) is guided laterally in the gas chamber (8) in at least two guide sections (17'; 24) which are axially spaced from one another.

8. A gas metering valve for metering and releasing a gaseous fuel, comprising: a housing (1) in which a gas chamber (8) having an inlet opening (9) and an outlet opening (10) is formed; a valve body (12) is longitudinally disposed within the gas chamber (8) for opening and closing the inlet opening (9) by longitudinal movement; the valve body (12) is movable by an electric actuator (18) and has a nozzle needle (30) disposed within the gas chamber (8) which cooperates with a nozzle seat (37) to open and close the outlet opening (10); and a coupler sleeve (20) is disposed between the valve body (12) and the nozzle needle (30) for transmitting the longitudinal movement of the valve body (12) to the nozzle needle (30), The coupler sleeve (20) is accommodated without clearance in the accommodation opening (14) of the valve body (12); 13. A gas metering valve, comprising: a coupling sleeve (20) laterally guided in the gas chamber (8) in at least two guide sections (17'; 24) which are axially spaced from one another.

9. 9. A gas metering valve according to claim 7 or 8, characterized in that the valve body (12) has a lateral guide clearance which is so large that it is radially guided only by the coupler sleeve (20).

10. 10. Gas metering valve according to claim 1, characterized in that the electric actuator is an electromagnet (18) and the valve body (12) is configured as a solenoid armature.

Images