Gas injector with armature damper

Abstract

The present invention relates to a gas injector for injecting a gaseous medium, comprising a closing element (2) which releases and closes a through opening (4) on a sealing seat (3), a restoring element (6) which restores the closing element (2) into a closed starting position, a magnetic actuator (5) with an armature which has a maximum armature stroke (SO), wherein the magnetic actuator (5) actuates the closing element (2), and an armature damper (7) which is configured, in the case of an opening operation of the gas injector, to reduce a speed of the armature (51) before the armature (51) comes into contact with an armature stop (53).

Description

[0001] Description

[0002] title

[0003] Gas injector with armature damper

[0004] State of the art

[0005] The present invention relates to a gas injector for injecting a gaseous medium, for example hydrogen or natural gas or the like, directly into a combustion chamber of an internal combustion engine with an armature damper.

[0006] Gas injectors are known in various designs from the prior art. Due to the gaseous medium that gas injectors inject, gas injectors must execute a very large stroke compared to injectors for liquid media, such as fuel injectors. However, this can lead to significant wear on components in gas injectors, particularly on the sealing seat and stroke limiter. The high switching forces required for gas injectors further increase wear on components during operation.

[0007] Disclosure of the invention

[0008] The gas injector according to the invention for injecting a gaseous medium, in particular for injecting hydrogen or natural gas, with the features of claim 1 has the advantage that component wear can be significantly reduced. In particular, wear on an armature can be significantly reduced. Furthermore, the gas injector according to the invention has significantly improved noise behavior. This is achieved according to the invention in that the gas injector has a closing element which opens and closes a through-opening on a sealing seat. Furthermore, the gas injector comprises a return element which returns the closing element to a closed initial position. Furthermore, the gas injector comprises a magnetic actuator with an armature, wherein the magnetic actuator actuates the closing element and wherein the armature has a maximum armature stroke SO.Furthermore, an armature damper is provided, which is configured to reduce the speed of the armature during an opening process of the gas injector before the armature hits an armature stop, in particular an inner pole of the magnetic actuator. This significantly reduces wear on the armature and the armature stop, and prevents excessive wear at the contact points between the armature and the armature stop during the opening stroke of the gas injector.

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

[0010] Preferably, the armature damper is located on a side of the armature facing away from the sealing seat. This ensures that the functionality and performance of the magnetic actuator are not compromised, and the armature can execute the maximum planned armature stroke SO up to the armature stop without interference from an armature damper in this area.

[0011] The armature damper preferably comprises a spring element arranged on the side of the armature facing away from the sealing seat. In other words, the spring element is arranged on the rear side of the armature. This provides many degrees of freedom regarding the design of the spring element. It also enables a very compact design of the gas injector.

[0012] Further preferably, the closing element comprises a valve needle and an armature bolt, with the armature being fixed to the armature bolt. The two-part construction of the closing element also increases the degree of freedom with regard to the design of the components of the gas injector.

[0013] According to a further preferred embodiment of the invention, the armature damper comprises a preferably pot-shaped support element, which is fixed to an inner housing of the gas injector. The support element serves to support the spring element. With a pot-shaped support element, the use of a cylindrical spring as the spring element also ensures radial positioning of the spring element.

[0014] More preferably, the armature damper further comprises a thrust washer and a first adjusting washer. The spring element of the armature damper is arranged between the thrust washer and the support element of the armature damper. Furthermore, a position of the thrust washer in the axial direction is defined by the first adjusting washer. This provides an easy-to-use adjustment option for a desired preload of the spring element of the armature damper.

[0015] According to a further preferred embodiment of the invention, the armature damper further comprises a second adjusting disk, which is fixed to the closing element. When the gas injector is closed, the second adjusting disk defines an axial gap S1 between the thrust disk and the second adjusting disk. The axial gap S1 is smaller than the maximum armature stroke SO. The second adjusting disk is preferably fixed to the armature bolt.

[0016] Further preferably, the support element has a guide area for the closing element, in particular for the anchor bolt, on an inner circumference.

[0017] The spring element of the armature damper is more preferably a cylindrical coil spring or a spring washer. The spring washer can, for example, be a wave spring or a disc spring or the like.

[0018] The gas injector preferably further comprises a hydraulic damper, which is arranged on a side of the closing element facing away from the sealing seat. The hydraulic damper is preferably designed to support the closing element during both the opening and closing processes. In conjunction with the armature damper, the armature is particularly well damped during the opening process, thus preventing wear on the armature and armature bolt. The hydraulic damper also allows for compensation for temperature-related changes in the length of the gas injector components.

[0019] Further preferably, the armature damper is configured to be activated with a time delay after the start of an opening process of the gas injector, wherein the axial gap between the thrust washer and the second adjusting washer defines the time delay. The gas injector is preferably an outward-opening gas injector. Further preferably, the gas injector is designed for the direct injection of a gaseous fuel into a combustion chamber of an internal combustion engine.

[0020] Furthermore, the present invention relates to an internal combustion engine with a gas injector according to the invention. The gas injector preferably injects hydrogen, natural gas, or another fuel gas directly into a combustion chamber of the internal combustion engine.

[0021] Short description of the drawings

[0022] Preferred embodiments of the invention are described in detail below with reference to the accompanying drawings. In the drawing:

[0023] Figure 1 is a schematic sectional view of a gas injector according to a first preferred embodiment of the invention,

[0024] Figure 2 is a schematic, enlarged partial sectional view of the

[0025] Gas injector of Figure 1 in the closed state,

[0026] Figure 3 is a schematic, enlarged partial sectional view of the

[0027] Gas injector of Figure 1 in partially opened state,

[0028] Figure 4 is a schematic sectional view of a gas injector according to a second preferred embodiment of the invention, and

[0029] Figure 5 is a schematic representation of a single part of the

[0030] Armature damper of the second embodiment of the gas injector of Figure 4.

[0031] Preferred embodiments of the invention

[0032] A gas injector 1 according to a first preferred embodiment of the invention is described in detail below with reference to Figures 1 to 3. As can be seen from Figure 1, the gas injector 1 for injecting a gaseous medium into a combustion chamber 30 of an internal combustion engine comprises a closing element 2 and a magnetic actuator 5, which actuates the closing element 2. The closing element 2 is designed in two parts and comprises a valve needle 20 and an armature bolt 21.

[0033] The magnetic actuator 5 comprises an inner pole 50, an armature 51, and a coil 52. An armature stop 53 is formed on the inner pole 50. The armature stop 53 limits the opening stroke of the closing element 2.

[0034] The closing element 2 has a valve plate 20a on the valve needle 20 on the side facing the combustion chamber 30, which seals against a sealing seat 3. During the opening process, the closing element 2 releases and closes an annular through-opening 4 on the sealing seat 3. The gas injector is thus an outward-opening injector, with the closing element 2 being moved outward into the combustion chamber 30 in the direction of arrow A (see Figure 1).

[0035] The injection of the gaseous fuel into the combustion chamber 30 is indicated in Figure 1 by the arrows C, whereby it should be noted that Figure 1 shows the closed state of the gas injector.

[0036] A gas inlet 31 is provided at the opposite end of the sealing seat 3. As can be seen from Figure 1, the gas inlet 31 is arranged in line with the closing element 2 on a central axis that defines an axial direction XX of the gas injector 1.

[0037] In Figure 1, the arrows B indicate the gas flow through the gas injector 1 starting from the gas inlet 31 to the sealing seat 3.

[0038] A return element 6 returns the gas injector 1 to the closed state shown in Figure 1 after an opening operation. In this exemplary embodiment, the return element is a cylindrical coil spring supported on a spring plate 60 and a housing component 10a. The gas injector 1 further comprises an armature damper 7, which is configured to decelerate and dampen the speed of the armature 51 before it strikes the armature stop 53 during an opening operation of the gas injector 1.

[0039] The armature damper 7 comprises a pot-shaped support element 70, a spring element 75 and an inner housing 71. The inner housing 71 is sleeve-shaped and fixed to the inner pole 50.

[0040] The armature damper 7 further comprises a thrust washer 72, a first adjusting washer 73, and a second adjusting washer 74. As can be seen from Figure 2, the spring element 75 is arranged between the thrust washer 72 and the cup-shaped support element 70. The cup-shaped design of the support element 70 stabilizes the spring element 75, which in this embodiment is a cylindrical helical spring, in the radial direction. In the closed state, which is shown in Figures 1 and 2, the spring element 75 has a spring force F, with which the thrust washer 72 is pressed against the first adjusting washer 73.

[0041] The first adjusting disc 73 is fixed to an inner circumference of the inner housing 71.

[0042] A guide 70a for the anchor bolt 21 is provided on the inner circumference of the support element 70.

[0043] The second adjusting disc 74 is fixed to the closing element 2, more precisely to the anchor bolt 21. In the closed state of the gas injector (Figure 2), an axial gap S1 exists between the second adjusting disc 74 and the thrust disc 72. Thus, a preload force of the spring element 75 can be adjusted by positioning the first adjusting disc 73 in the axial direction XX, which defines an axial position of the thrust disc 72.

[0044] The thrust washer 72 is arranged axially movable inside the inner housing 71.

[0045] The anchor bolt 21 is, as shown in Figures 1 and 2, through the

[0046] The inner pole 50 is guided freely through, preferably with a guide 50a for the armature bolt 21. The armature 51 is firmly connected to the armature bolt 21 by means of a welded connection 51a.

[0047] In the closed state of the gas injector 1, a maximum opening stroke of the closing element 2 is defined by an armature stroke SO. The armature stroke SO is formed between the armature 51 and the inner pole 50. The armature stroke SO is larger than the axial gap S1 between the second adjusting disk 74 and the thrust disk 72.

[0048] By providing the axial gap S1, the armature damper 7 is activated with a time delay during an opening process of the gas injector. For an opening process of the gas injector, the coil 52 is energized, causing the armature 51 to move in the direction of arrow D (see Figure 2) towards the inner pole.

[0049] 50 is pulled. Due to the movement of the armature 51, the armature bolt 21 and thus also the valve needle 20 are moved in the axial direction XX, so that the gas injector 1 opens at the sealing seat 3 and releases the through opening 4.

[0050] This allows the gaseous fuel to be injected into the combustion chamber 30 (arrows C). Since the second adjusting disc 74 is firmly connected to the armature bolt 21, the second adjusting disc 74 is also moved in the axial direction XX during the opening process. After the axial gap S1 has been closed, the second adjusting disc 74 rests against the pressure disc 72. This state is shown in Figure 3. Until the axial gap S1 has been overcome, the armature damper 7 is not yet in action, which enables the delayed actuation of the armature damper 7.

[0051] When the armature 51 is pulled further in the direction of arrow D from the position shown in Figure 2 onto the inner pole 50, the second adjusting disc 74 also moves further in the direction of the sealing seat 3, taking with it the pressure disc 72, which is arranged freely movable in the inner housing 71. This compresses the spring element 75, whereby the armature

[0052] 51 is decelerated in its speed of movement. In the state shown in Figure 3, the armature 51 still has to overcome the remaining partial axial gap S2 between the armature 51 and the inner pole 50 until the gas injector is fully opened. Complete opening occurs when the armature 51 rests against the armature stop 53 on the inner pole 50. When the remaining axial gap S2 is covered, the armature damper 7 is activated so that the impact speed of the armature 51 on the inner pole 50 is significantly reduced, thereby reducing wear on these components. Furthermore, the impact noise of the armature 51 on the inner pole 50 can also be reduced, thereby significantly improving the noise behavior of the gas injector 1.

[0053] As soon as the blow-in process is complete, the current supply to coil 52 is stopped, so that the reset element 6 returns the closing element 2 to the initial position shown in Figures 1 and 2. In doing so, the armature 51 is returned to its initial position, away from the armature stop 53. The thrust washer 72 is also returned to the closed position shown in Figure 2 on the first adjusting disc 73 by means of the spring element 75.

[0054] The gas injector 1 further comprises a hydraulic damper 8, which is operatively connected to the closing element 2. The hydraulic damper 8 is configured to decelerate and dampen the closing element, particularly during a return from the open state to the closed state. This minimizes wear on the sealing seat 3 of the gas injector. By providing the armature damper 7, the hydraulic damper 8 can be very simply constructed and, in particular, can be configured only to damp the closing element 2 during the return process.

[0055] Thus, the armature damper 7 can be optimally designed for the armature and damping during the opening process and the hydraulic damper 8 can be optimally designed for damping when closing the gas injector.

[0056] Figures 4 and 5 show a gas injector 1 according to a second embodiment of the invention, wherein identical or functionally identical parts are designated by the same reference numerals.

[0057] As can be seen particularly from Figure 5, the armature damper 7 of the second embodiment comprises a wave spring as the spring element 75. As in the first embodiment, the wave spring is arranged between the support element 70 and the thrust washer 72. The support element 70 can be designed as a simple washer. Otherwise, this embodiment corresponds to the previous embodiment, so reference can be made to the description given there.

Claims

Claims 1. Gas injector for injecting a gaseous medium, comprising - a closing element (2) which opens and closes a through opening (4) at a sealing seat (3), - a return element (6) which returns the closing element (2) to a closed initial position, - a magnetic actuator (5) with an armature (51) which has a maximum armature stroke (SO), wherein the magnetic actuator (5) actuates the closing element (2), and - an armature damper (7) which is designed to reduce a speed of the armature (51) before the armature (51) hits an armature stop (53) during an opening process of the gas injector.

2. Gas injector according to claim 1, wherein the armature damper (7) is arranged on a side of the armature (51) facing away from the sealing seat (3).

3. Gas injector according to claim 2, wherein the armature damper (7) has a spring element (75) which is arranged on a side of the armature (51) facing away from the sealing seat (3).

4. Gas injector according to one of the preceding claims, wherein the closing element (2) comprises a valve needle (20) and an armature bolt (21), wherein the armature (51) is fixed to the armature bolt (21).

5. Gas injector according to one of claims 3 or 4, wherein the armature damper (7) comprises a support element (70) for the spring element (75) and an inner housing (71), wherein the support element (70) is fixed to the inner housing (71).

6. Gas injector according to claim 5, wherein the armature damper (7) further comprises a pressure disk (72) and a first adjusting disk (73), wherein the A spring element (75) is arranged between the thrust washer (72) and the support element (70), and a position of the thrust washer (72) in the axial direction (XX) is defined by means of the first adjusting washer (73). Gas injector according to claim 6, further comprising a second adjusting washer (74) which is fixed to the closing element (2), wherein the second adjusting disk (74) defines an axial gap (S1) between the pressure disk (72) and the second adjusting disk (74) in the closed state of the gas injector, and wherein the axial gap (S1) is smaller than the maximum armature stroke (S0). Gas injector according to one of the preceding claims, wherein the support element (70) has a guide region (70a) for the closing element (2) on an inner circumference. Gas injector according to one of claims 3 to 8, wherein the spring element (75) is a helical spring or a spring washer or a corrugated spring or a disc spring. Gas injector according to one of claims 7 to 9, wherein the armature damper (7) is configured to be activated with a time delay after the start of an opening process of the gas injector, wherein the axial gap (S1) between the pressure washer (72) and the second adjusting washer (74) defines the time delay. Gas injector according to one of the preceding claims, further comprising a hydraulic damper (8) which is arranged at an end of the closing element (2) facing away from the sealing seat and is configured to perform damping at least during an opening process of the gas injector.

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