Gas injector comprising a non-return valve

Abstract

The present invention relates to a gas injector (1) for injecting a gaseous medium. The gaseous medium is in particular a gaseous fuel. The gas injector (1) comprises: a closing element (2) for opening and closing at least one through-opening (3) at a first sealing seat (21); an actuator (4) for actuating the closing element (2); a blow cap (5) having an outlet opening (51); and a non-return valve (6). The blow cap (5) is arranged at an injection-side end of the gas injector (1), and the non-return valve (6) is arranged between the outlet opening (51) and the closing element (2). The non-return valve (6) is designed to seal at a second sealing seat (61) in order to prevent a backflow from the outlet opening (51) in the direction of the closing element (2).

Description

[0001] Description

[0002] title

[0003] Gas injector with check valve

[0004] State of the art

[0005] The present invention relates to a gas injector for injecting a gaseous medium, in particular a gaseous fuel such as hydrogen or CNG.

[0006] Gas injectors are known from the state of the art in various designs. Due to cost advantages and improved environmental compatibility, gaseous fuels have recently become increasingly popular. For gas injectors in which a sealing seat is positioned close to the combustion chamber, plastic sealing seats are unsuitable due to the high thermal loads. Metallic sealing seats have the disadvantage of not reliably meeting strict sealing requirements, even with slight seat wear. A leaky sealing seat can lead to premature pre-ignition of gas escaping from the gas injector during operation. This malfunction causes the cylinder pressure to rise too early and very steeply, resulting in severe mechanical stress on the components. Combustion in the area of ​​the sealing seat can be maintained by the leak until the next actuation.During the subsequent activation, this flame can initiate premature ignition at the very beginning of the activation, which severely impairs the functioning of the internal combustion engine.

[0007] Disclosure of the invention

[0008] The inventive gas injector for injecting a gaseous medium, in particular a gaseous fuel, with the features of claim 1 has the advantage that a check valve between the sealing seat of a closing element and an outlet opening prevents the backflow of a fluid toward the closing element. Thus, a potential ignition at the sealing seat of the closing element due to insufficient air supply can be quickly extinguished. The gas injector can be operated with the aid of the check valve according to the invention even with increased seat leakage. Thus, the gas injector according to the invention can, among other things, contribute to the safe operation of an internal combustion engine. This is achieved according to the invention in that the gas injector has a closing element for opening and closing at least one through-opening at a first sealing seat. Furthermore, an actuator is provided for actuating the closing element.The gas injector also includes a check valve and, on the inlet end, a blow cap with an outlet opening. The blow cap enables targeted injection of a gaseous medium and protects the check valve. The check valve is arranged between the outlet opening and the closing element and is designed to seal against a second sealing seat to prevent backflow from the outlet opening towards the closing element. When the closing element is opened, a gaseous medium flows into the space between the first and second sealing seats. The inflowing gaseous medium causes the check valve to open, allowing the gaseous medium to escape from the gas injector through the outlet opening in the blow cap. When the closing element is closed, the gas flow is stopped and the check valve closes.The check valve thus prevents gas from flowing from the outlet opening toward the closing element. Due to the positioning of the check valve, the second sealing seat is located closer to the outlet opening than the first sealing seat. Due to the higher thermal load, the second sealing seat on the check valve is preferably metallic. The first sealing seat can be either metallic, shielded by the check valve, to increase durability, or plastic to improve sealing properties.

[0009] The subclaims show preferred developments of the invention.

[0010] Particularly preferably, the check valve seals against an annular sealing disc via a seat surface. The sealing disc is preferably arranged between the check valve and the closing element. Further preferably, the annular sealing disc has a conical surface for flow control, which is directed toward the closing element. Thus, the conical surface enables efficient flow around the sealing disc and reduces the flow resistance of a gaseous medium flowing through the gas injector.

[0011] In a preferred embodiment, the check valve divides the blow cap into a first space between the first sealing seat and the second sealing seat, and a second space between the second sealing seat and the outlet opening. The division into a first and second space harmonizes the gas flow and prevents pressure fluctuations in the gas flow.

[0012] In particular, the first chamber is preferably smaller than the second chamber. Due to the small volume of the first chamber, any potentially combustible mixture is quickly consumed in the event of an ignition, since the check valve prevents new combustible mixture from flowing from the outlet opening toward the closing element. Thus, the smaller first chamber prevents pre-ignition in the gas injector.

[0013] Another advantage is that the second sealing seat is a flat sealing seat. Flat sealing seats are inexpensive to manufacture and enable robust sealing.

[0014] The check valve is preferably passively actuated. Passive check valves change their opening state based on a passively controlled force, for example, a spring force, a magnetic force, gravitational force, or a hydraulic force. Thus, passive check valves are robust and require no control effort.

[0015] Alternatively, the check valve is preferably actively actuated. Active control allows the check valve to be opened or closed as needed. Furthermore, information about the check valve's functionality can be easily collected, allowing wear to be detected early.

[0016] The gas injector further preferably comprises a spring that exerts a spring force on the non-return valve in the direction of the closing element to close the non-return element. Thus, the spring force of the non-return valve is overcome by the pressure of the gas flowing in through the open closing element, the non-return valve opens, and allows gas to flow out of the gas injector. As soon as the closing element is closed, no more incoming gas exerts pressure on the non-return valve, and the non-return valve is closed by the spring force. The opening behavior can advantageously be varied by using the spring and adjusting the spring constant.

[0017] According to a further advantageous embodiment of the invention, the check valve is a one-piece component with an integrated spring. In particular, the check valve is a stamped component. One-piece check valves are inexpensive to manufacture and assemble. Due to the small number of components, one-piece check valves are also robust.

[0018] The one-piece check valve preferably has spring arms. When installed, the spring arms preferably exert a spring force that pushes the check valve toward the second sealing seat. Spring arms can be easily integrated into cost-effective stamped components. Furthermore, when the check valve is open, the gas flow can bypass the check valve along the spring arms.

[0019] Further advantageously, the gas injector comprises a support disc on which the check valve is arranged. The support disc is preferably arranged between the check valve and the outlet opening. The support disc is designed to absorb the force of the check valve in the direction of the second sealing seat. By positioning the support disc, a preload force on the second sealing seat can be adjusted during assembly. Alternatively, with a defined position of the support disc, the preload force can be varied by positioning the annular sealing disc. This allows the check valve to be optimally adjusted to the injection conditions of the gas injector.

[0020] Preferably, the check valve and / or the support plate comprise at least one recess. The recess results in an optimized gas flow from the closing element, around the check valve, to the outlet opening. Thus, the targeted provision of recesses can reduce the flow resistance within the gas injector. Further preferably, the gas injector is configured to inject the gaseous fuel directly into a combustion chamber.

[0021] Furthermore, the present invention relates to an internal combustion engine with a gas injector according to the invention, the combustion chamber, and a cylinder head with a receiving shaft for the gas injector. Due to the check valve, the tightness of the gas injector is significantly improved and pre-ignition of the gaseous fuel during operation is prevented.

[0022] Short description of the drawings

[0023] Embodiments of the invention are described in detail below with reference to the accompanying drawings. In the drawing:

[0024] Figure 1 is a schematic sectional view of a gas injector according to a first preferred embodiment in the closed state,

[0025] Figure 2 is a schematic sectional view of the gas injector according to the first embodiment in the open state and

[0026] Figure 3 is a schematic view of a one-piece check valve of a gas injector according to a second embodiment of the invention.

[0027] Embodiments of the invention

[0028] A gas injector 1 according to a first preferred embodiment of the invention is described in detail below with reference to Figures 1 and 2.

[0029] Figure 1 shows a gas injector 1 in a cylinder head 13 of an internal combustion engine. An injection-side end 12 of the gas injector 1 is arranged in a combustion chamber 9 of the internal combustion engine. As can be seen from Figure 1, the gas injector 1 for injecting a gaseous medium comprises a housing 11 in which an actuator 4 is arranged. The actuator 4 is connected to a closing element 2, which is designed to seal the gas injector 1 at a first sealing seat 21 against unwanted escape of the gaseous medium.

[0030] At the injection-side end 12 of the gas injector 1, a cylindrical blow cap 5 is arranged coaxially to the central axis X - X of the housing 11 of the gas injector 1. An outlet opening 51 is formed in the blow cap 5 coaxially to a central axis X - X of the gas injector 1.

[0031] A check valve 6 is arranged within the blow cap 5 between the outlet opening 51 and the first sealing seat 21 of the closing element 2. The check valve 6 is connected to a support disc 8 on the inlet side via a spring 62. Toward the closing element 2, the check valve 6 forms a second sealing seat 61 on an annular sealing disc 7.

[0032] Thus, a first space 52 is formed between the first sealing seat 21 and the second sealing seat 61 and a second space 53 is formed between the second sealing seat 61 and the outlet opening 51.

[0033] The check valve 6 has a T-shaped cross-section with a flat seating surface oriented perpendicular to the central axis X-X and in the direction of the closing element 2. On the opposite side, the check valve 6 includes a central pin-shaped projection designed to receive the spring 6. In the radially outer region, the check valve 6 has recesses 65.

[0034] In the closed state, the recesses 65 are sealed by the sealing disc 7, so that no gas can flow from the first chamber 52 through the second sealing seat 61 into the second chamber 53, or vice versa. The second sealing seat 61 is a flat seal oriented perpendicular to the central axis X-X of the gas injector 1.

[0035] The annular sealing disc 7 is connected flush with the blow cap 5. The connection can be welded or caulked, for example. In the direction of the closing element 2, the sealing disc 7 has a conical surface 71, which optimizes the flow pattern in the gas injector 1 and ensures low flow resistance.

[0036] A preloaded spiral spring 62 is arranged between the support disc 8 and the check valve 6. The preload can be determined by the length and spring constant of the spring 62, as well as by the distance between the support disc 8 and the sealing disc 7. The smaller the distance between the support disc 8 and the sealing disc 7, the higher the preload force of the spring 62.

[0037] The support disk 8 is preferably a perforated disk, has a plurality of recesses 81, and is arranged perpendicular to the central axis X-X. The recesses 81 can be circular or have other shapes and enable low flow resistance of the gas flow from the closing element 2 in the direction of the outlet opening 51. The support disk 8 is connected circumferentially to the blow cap 5. The connection between the support disk 8 and the blow cap 5 can, for example, be welded or caulked. The contact area of ​​the support disk 8 with the spring 62 has no recess. Furthermore, the area which is radially inside the contact area with the spring 62 is formed without recesses and serves as a second stop of the check valve 6 in the open state.

[0038] The second space 53 is arranged inside the blow cap 5 between the support disk 8 and the outlet opening 51. Radially outside the outlet opening 51, in the direction of the gas injector 1, the blow cap 5 has a conical surface that directs the gas flow toward the outlet opening 51.

[0039] Figure 2 shows the gas injector 1 of the first embodiment in an open state.

[0040] By an axial stroke movement of the closing element 2 along the central axis XX in the direction of the injection-side end 12, a through-opening 3 is formed in the region of the first sealing seat 21 between the housing 11 and the closing element 2. The through-opening 3 enables a gas flow 10 in the direction of the first chamber 52. If the pressure force in the direction of the injection-side end 12, due to a pressure difference between the first chamber 52 and the second chamber 53, is greater than the spring force in the direction of the closing element 2, the check valve 6 is pressed in the direction of the injection-side end 12 and allows the gas flow 10 to flow through the lateral recesses 65 from the first chamber 52, past the check valve 6, into the second chamber 53 (see Figure 2).

[0041] From the second space 53, the gas flow 10 escapes through the outlet opening

[0042] 51 in the blow cap 5 from the gas injector 1 and into the combustion chamber 9. In the combustion chamber 9, an ignitable mixture is created with the help of the blown-in gas.

[0043] By a lifting movement of the closing element 2 against the injection-side end 12, the passage opening 3 is closed and the injection process is terminated. Due to the decreasing pressure difference between the first chamber

[0044] 52 and second chamber 53, the pressure force on the check valve 6 decreases and the spring 62 presses the check valve 6 against the second sealing seat 61.

[0045] After the injection process is completed, the ignitable mixture in the combustion chamber is ignited, resulting in a pressure increase in the combustion chamber 9 and the second chamber 53 connected via the outlet opening 51. The resulting pressure difference between the first chamber 52 and the second chamber 53 exerts a compressive force on the check valve 6 in the direction of the closing element 3, whereby the check valve 6 is pressed more strongly against the second sealing seat 61. The stronger seal of the check valve 6 at the second sealing seat 61 thus prevents gas from flowing from the combustion chamber 9 toward the first sealing seat 21 on the closing element 2 and igniting escaping gas there.

[0046] Figure 3 shows a plan view of a one-piece check valve 6 according to a second embodiment. The one-piece check valve 6 is a stamped component made of sheet metal with three integrated spring arms 64.

[0047] The spring arms 64 are arranged via a web on the outer radius of a base plate 66 and are evenly distributed around the circumference. The elongated spring arms 64 are arranged parallel to the circumference of the base plate 66. To generate a spring force, the spring arms 64 are bent downward in the direction of the image plane. The radially outermost region of the base plate 66 comprises a seating surface 63, which is shown in Figure 3 radially outside a dashed line L. The seating surface 63 is designed to be pressed against the sealing disc 7 with the aid of the spring arms 64 and to form the second sealing seat 53, which prevents the backflow of a gas from the outlet opening 51 in the direction of the closing element 2.

Claims

Claims 1. Gas injector (1) for injecting a gaseous medium, in particular a gaseous fuel, comprising • a closing element (2) for releasing and closing at least one through-opening (3) at a first sealing seat (21), • an actuator (4) for actuating the locking element (2), • a blow cap (5) with an outlet opening (51), and • a check valve (6), • wherein the blow cap (5) is arranged at an inlet end of the gas injector (1), • wherein the check valve (6) is arranged between the outlet opening (51) and the closing element (2), and • wherein the check valve (6) is designed to seal at a second sealing seat (61) in order to prevent backflow from the outlet opening (51) in the direction of the closing element (2).

2. Gas injector (1) according to claim 1, wherein the check valve (6) seals via a seat surface (63) against an annular sealing disc (7) which is arranged in the blow cap (5) between the check valve (6) and the closing element (2).

3. Gas injector (1) according to claim 2, wherein the annular sealing disc (7) has a conical surface (71) for flow shaping, which is directed in the direction of the closing element (2).

4. Gas injector (1) according to one of the preceding claims, wherein the check valve (6) divides the blow cap (5) into a first space (52) between the first sealing seat (21) and the second sealing seat (61) and a second space (53) between the second sealing seat (61) and the outlet opening (51).

5. Gas injector (1) according to claim 4, wherein the first space (52) is smaller than the second space (53).

6. Gas injector (1) according to one of the preceding claims, wherein the second sealing seat (61) is a flat sealing seat.

7. Gas injector (1) according to one of the preceding claims, wherein the check valve (6) is passively actuated.

8. Gas injector (1) according to one of claims 1 to 6, wherein the check valve (6) is actively operable.

9. Gas injector (1) according to one of the preceding claims, comprising a spring (62) which exerts a spring force on the check valve (6) in the direction of the closing element (2) in order to close the check valve (6).

10. Gas injector (1) according to claim 9, wherein the check valve (6) is a one-piece component and wherein the spring (62) is integrated into the check valve (6).

11. Gas injector (1) according to claim 10, wherein the check valve (6) has spring arms (64).

12. Gas injector (1) according to one of the preceding claims, wherein the check valve (6) is arranged on a support disc (8).

13. Gas injector (1) according to claim 12, wherein the check valve (6) comprises at least one recess (65) and / or wherein the support disc (8) comprises at least one recess (81).

14. Gas injector (1) according to one of the preceding claims, wherein the gas injector (1) is arranged to inject the gaseous fuel directly into a combustion chamber (9).

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