Gas injector with improved actuator and method for operating a gas injector

Abstract

The invention relates to a gas injector for injecting a gaseous medium, comprising a closing element (2) having a valve needle (3) which releases and closes a gas path (8) on a sealing seat (6); actuator for actuating a closing element (2), comprising a first electromagnetic actuator (10) and a second electromagnetic actuator (20), the first electromagnetic actuator (10) comprising a first coil (11), a first inner pole (12) and a first armature (13), the second electromagnetic actuator (20) comprising a second coil (21), a second inner pole (22) and a second armature (23), the first electromagnetic actuator (10) and the second electromagnetic actuator (20) are arranged in series with one another in the axial direction (X-X) of the gas injector; and a control unit (100) provided for actuating the first electromagnetic actuator (10) and the second electromagnetic actuator (20). The invention also relates to a method for operating a gas injector.

Description

Technical Field

[0001] The invention relates to a gas injector for injecting a gaseous medium with an improved actuator, which comprises two electromagnetic actuators. The invention also relates to a method for operating a gas injector. Background Art

[0002] Gas injectors are known from the prior art in different configurations. A series of problems with gas injectors is that gaseous media have a larger volume than injectors for liquid media. As a result, the gas injector must release a larger cross section for blowing, which also leads to a larger stroke. In addition, the blowing pressure is usually significantly lower than in the case of liquid media, so that there is a greater force requirement for the gas injector in general to resist the combustion chamber pressure to achieve the opening process. For example, this increased force requirement can be achieved by using a larger electromagnetic actuator. However, this has the following disadvantages: more magnetic material is required, which makes such electromagnetic actuators particularly expensive. In addition, especially in the case of internal combustion engines used in direct-blown gas injectors, there are usually installation space problems due to limited installation space. Therefore, the diameter of the gas injector is particularly limited in terms of its size. Summary of the invention

[0003] In contrast, the gas injector according to the present invention has the advantage that the gas injector can provide high force application (Kraftentfaltung) for the opening process of the gas injector, wherein the installation space of the gas injector, in particular the outer diameter of the gas injector, can be kept small. As a result, the gas injector according to the present invention can also be used in an internal combustion engine without changing the geometry of the cylinder head for direct blowing. Here, the gas injector according to the present invention can be adapted to various cylinder heads of different internal combustion engines. As a result, a great advantage is obtained when manufacturing the gas injector, and the injector can be manufactured as a batch component. In addition, the impact on the gas injector component during the opening process and the closing process can be reduced in a targeted manner by means of the gas injector according to the present invention. As a result, the service life of the gas injector can be significantly extended, especially the operating noise can be reduced.

[0004] This is achieved according to the invention in the following manner: the gas injector comprises a closing element with a valve needle, which releases and closes the gas path at the sealing seat. In addition, the gas injector comprises an actuator for operating the closing element. The actuator comprises a first electromagnetic actuator and a second electromagnetic actuator. The first electromagnetic actuator comprises a first coil, a first inner pole and a first armature. The second electromagnetic actuator comprises a second coil, a second inner pole and a second armature. The first electromagnetic actuator and the second electromagnetic actuator are arranged in series with each other, and a control unit is also provided for controlling the first electromagnetic actuator and the second electromagnetic actuator. Therefore, according to the invention, two smaller, lower-power electromagnetic actuators are used in series instead of increasing one electromagnetic actuator, whereby the forces of the two electromagnetic actuators are added. Since the electromagnetic actuator is smaller, the outer diameter of the gas injector will not be unnecessarily increased, so that the gas injector can be installed in an existing cylinder head, which can continue to be used by the manufacturer of the internal combustion engine without modification. Here, the control unit is either arranged in a manner that is operatively connected to the gas injector as part of the controller, or even arranged in a manner that is directly integrated on the gas injector.

[0005] Developments of the invention result from preferred embodiments.

[0006] Preferably, the first electromagnetic actuator has a first armature column, which is fixedly connected to the first armature. The first armature column is operatively connected to the valve needle. The second electromagnetic actuator includes a second armature column operatively connected to the first armature column. Preferably, the two armatures and the two armature columns have the same geometric dimensions.

[0007] The operative connection between the first armature pin and the valve needle is preferably achieved by planar contact of mutually opposing surfaces, which are perpendicular to the central axis of the gas injector. The operative connection between the first armature pin and the second armature pin is also preferably achieved by planar contact between the two armature pins.

[0008] In order to realize a particularly compact structure, the first coil and the second coil of the two electromagnetic actuators are preferably wound on a common winding carrier. Here, the common winding carrier is preferably configured as a hollow cylinder and has a notch for receiving the windings of the first coil and the second coil of the two electromagnetic actuators.

[0009] Particularly preferably, the first coil and the second coil are wound in a group, wherein the first coil and the second coil each have an even number of layers, for example "n equals 2 or 4 or 6 or 8". Particularly preferably, the two windings of the first coil and the second coil are implemented so that the wire for the winding comes out again on the same axial side of the coil after the winding is completed. For example, this can be achieved in that in the case of the first coil, an odd number of layers, for example three layers, are first wound, and then a second coil with four layers is wound with the same wire, which is then guided back to the first coil and the remaining last layer is wound onto the first winding. As a result, the starting point and end point of the wire can enter and exit on the same side of the coil. This also has the advantage that only one electrical connection needs to be provided.

[0010] Alternatively, the connections for the two windings of the first coil and the second coil can also be led outwards separately. This has the advantage that the first coil and the second coil can be controlled separately and individually. In this way, in particular, the travel course of the two armatures of the gas injector can be actively influenced. In particular, the energization of the first coil and the second coil can be started and / or ended at different times. Alternatively, the energization of the first coil and the second coil can be started at different times and ended at the same time.

[0011] As the magnetic material of the first electromagnetic actuator and the second electromagnetic actuator, a mixture of iron and cobalt materials is preferably used.

[0012] Further preferably, the first electromagnetic actuator and the second electromagnetic actuator have the same power. Thus, the two electromagnetic actuators can provide the same force for the opening process, and the two forces are then added during the opening process.

[0013] According to another preferred configuration of the present invention, the first armature stroke of the first armature is different from the second armature stroke of the second armature. Preferably, the first armature stroke is smaller than the second armature stroke. This ensures that a defined stop of the first armature can always be achieved during the opening process of the gas injector. If the first armature stroke is smaller than the second armature stroke, it is also ensured that the armature of the second electromagnetic actuator has a small residual gap relative to the second inner pole in all operating states. As a result, surface hardening of the components of the second electromagnetic circuit can preferably be avoided. As a result, a significant cost reduction of the second electromagnetic actuator can be achieved.

[0014] Preferably, the first armature stroke is approximately 200 μm and the second armature stroke is approximately 220 μm.

[0015] Further preferably, a guide element is arranged between the first electromagnetic actuator and the second electromagnetic actuator, wherein the guide element guides both the first armature column and the second armature column. The guide element is preferably a hollow cylinder. Further preferably, the guide element is made of non-magnetic material.

[0016] Further preferably, the two armature strokes of the two electromagnetic actuators are set differently, so that the second armature stroke of the second electromagnetic actuator is significantly smaller than the first armature stroke of the first electromagnetic actuator. Due to the smaller second armature stroke, the second electromagnetic actuator has significantly greater force and can push the first armature column more forcefully via the second armature column, thereby also pushing the valve needle more forcefully until the second armature stops. At this point in time, the first armature stroke of the first electromagnetic actuator has been reduced so much that the opening process can be achieved even without further cooperation of the second electromagnetic actuator.

[0017] Furthermore, the invention relates to a method for operating a gas injector according to the invention. According to the method according to the invention, during the opening process of the gas injector, the control unit controls the first electromagnetic actuator and / or the second electromagnetic actuator in such a way that the first electromagnetic actuator and / or the second electromagnetic actuator are already switched off before reaching the corresponding full stroke. As a result, in particular, the so-called oscillation of the valve needle during opening can be reduced, because the opening force is reduced before the full stroke. Further preferably, in the method according to the invention, during the closing process of the gas injector, an electromagnetic actuator is actively operated in order to brake the valve needle before reaching the sealing seat. As a result, the impact pulse of the valve needle into the sealing seat can be reduced, which is advantageous in terms of wear of the gas injector and the occurrence of so-called bounces, in which the gas injector briefly opens again due to rebound after reaching the sealing seat. The braking force can be easily controlled by the current supplied in the first coil and / or the second coil.

[0018] The gas injector according to the invention and the method according to the invention are particularly preferably used in the direct injection of fuel into an internal combustion engine. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the accompanying drawings:

[0020] Figure 1 A schematic cross-sectional view of a gas injector according to a preferred embodiment of the present invention is shown;

[0021] Figure 2 A graph is shown which shows a comparison of the magnetic force of a single coil, the magnetic force of a double coil according to the invention with the same stroke and the magnetic force of a double coil according to the invention with a stroke offset;

[0022] Figure 3 A graph is shown which shows a comparison of the valve needle acceleration of a single coil, the valve needle acceleration of a double coil according to the invention with the same stroke and the valve needle acceleration of a double coil according to the invention with a stroke offset, and

[0023] Figure 4 A graph is shown which shows a comparison of the valve needle speed of a single coil, the valve needle speed of a double coil according to the invention with the same stroke and the valve needle speed of a double coil according to the invention with a stroke offset. DETAILED DESCRIPTION

[0024] Below, refer to Figures 1 to 4 Preferred embodiments of the present invention are described in detail.

[0025] like Figure 1 As shown, the gas injector 1 comprises a closing element 2 with a valve needle 3. The valve needle 3 has a valve disk 30 which, at a sealing seat 6, opens and closes a gas path 8 for injecting a gaseous medium into a combustion chamber 7.

[0026] The gas injector 1 further comprises an actuator for operating the closing element 2. Here, the actuator comprises a first electromagnetic actuator 10 and a second electromagnetic actuator 20.

[0027] The first electromagnetic actuator 10 has a first coil 11 , a first inner pole 12 , a first armature 13 , a first armature pin 14 and a first electrical connection 15 .

[0028] The second electromagnetic actuator 20 has a second coil 21 , a second inner pole 22 , a second armature 23 , a second armature pin 24 and a second electrical connection 25 .

[0029] like Figure 1 As shown, the first electromagnetic actuator 10 and the second electromagnetic actuator 20 are arranged in series in the axial direction XX of the gas injector. Here, the first electromagnetic actuator 10 is arranged between the second electromagnetic actuator 20 and the valve needle 3 in the axial direction.

[0030] The first coil 11 and the second coil 21 are arranged on a common winding support 80. The winding support 80 is made of a non-magnetic material, preferably a non-magnetic austenitic material. The common winding support preferably has a notch on its outer periphery for receiving the windings of the first coil and the second coil. The common winding support 80 further forms a housing part of the lubricant chamber 4.

[0031] The valve needle 3 has a contact surface 31 at the end facing away from the sealing seat 6. This contact surface is in contact with the contact surface 140 of the first armature pin 14. In this case, the two contact surfaces are oriented perpendicularly to the axial direction XX of the gas injector.

[0032] Furthermore, the first armature pin 14 has a further contact surface 141 at its end facing away from the sealing seat. This contact surface 141 contacts the contact surface 240 of the second armature pin 24. These contact surfaces are also oriented perpendicularly to the axial direction XX of the gas injector.

[0033] Figure 1 The closed state of the gas injector is shown. Here, the contact surfaces 31 and 140 and the contact surfaces 141 and 240 are in direct contact with each other. Therefore, the valve needle 3, the first armature column 14 and the second armature column 24 are operatively connected in the axial direction, but they can move independently of each other.

[0034] A preload element (not shown) holds valve needle 3 in the closed state.

[0035] The gas injector 1 further comprises a lubricant chamber 4 which is filled with lubricant. In the lubricant chamber 4, in particular, two armatures 13, 23 are arranged. This reduces the friction during the movement of the armature and the armature pin on the corresponding guide.

[0036] Here, a guide element 9 is provided in the lubricant chamber 4, in which the first armature column 14 is guided at its end facing away from the sealing seat, and the second armature column 24 is guided at its end facing the sealing seat. It should be noted that other guide components can also be provided. Corresponding through openings are provided in each component, so that the lubricant, such as oil, etc., located in the lubricant chamber 4 can be distributed to the entire lubricant chamber 4.

[0037] In order to establish the movability of valve needle 3 , a bellows 5 is also provided which is also a wall region of lubricant chamber 4 .

[0038] The first electromagnetic actuator 10 has a first armature stroke H1 until the first armature 13 stops on the inner pole 12. The second electromagnetic actuator 20 has a second armature stroke H2 until the second armature 23 stops on the second inner pole 22. In this embodiment, the first armature stroke H1 and the second armature stroke H2 are equal.

[0039] However, it should be noted that it may also be advantageous if the armature strokes are different. In particular, the second armature stroke H2 is smaller than the first armature stroke H1.

[0040] Here, the gas injector according to the present invention functions as follows. Figure 1 Based on the closed state of the gas injector shown in FIG, the control unit 100 energizes the first electromagnetic actuator 10 and the second electromagnetic actuator 20. Here, the two electromagnetic actuators can be controlled separately by the control unit 100. Here, the control unit 100 is either arranged in a manner operatively connected to the gas injector as part of a controller, or even arranged in a manner directly integrated on the gas injector.

[0041] In the illustrated embodiment in which the first armature stroke H1 is equal to the second armature stroke H2, preferably, the two coils of the electromagnetic actuator 10, 20 are energized simultaneously and for the same duration. As a result, the first armature 13 and the second armature 23 move simultaneously in the axial direction toward the sealing seat 6. Since the two armatures are fixedly connected to the corresponding armature columns 14, 24 and are operatively connected to each other at the contact surface, the valve needle 3 also moves in the axial direction, so that the gas injector 1 opens. As a result, the gaseous medium is directly blown into the combustion chamber 7.

[0042] If the blowing is to be ended, the energization of the two coils of the two electromagnetic actuators 10, 20 is terminated, so that the reset element (not shown) resets the valve needle 3 and thus also resets the two armature pins 14, 24 to the position in which they are located. Figure 1 The closed initial position is shown in .

[0043] exist Figures 2 to 4 In FIG. 3 , three graphs are shown showing different sizes of the first electromagnetic actuator and the second electromagnetic actuator compared to the only electromagnetic actuator shown in the prior art. Figures 2 to 4 In FIG. 1 , a single electromagnetic actuator with a single coil is correspondingly shown as a dashed curve and is denoted by K1 .

[0044] Now, the method according to the invention for operating a gas injector 1 can be carried out in different ways. Figure 1 As described above, in the gas injector 1 in which the first armature stroke H1 is equal to the second armature stroke H2, Figures 2 to 4 The curves in the curve diagram in are respectively referred to as K2. In the embodiment where the first armature stroke H1 is not equal to the second armature stroke H2, Figures 2 to 4 It is indicated by the reference sign K3.

[0045] Figure 2 A comparison of the magnetic forces is shown schematically. During the opening process, a single coil (curve K1) has 100% magnetic force at the travel stop H. In this case, with only one coil, the travel of the armature starts at about 500 μm and ends at the travel stop H at about 20 μm. The total travel from the closed state to the fully open state is therefore about 480 μm. For comparison, Figure 2 The magnetic force in the case of using two electromagnetic actuators with the same stroke is shown by curve K2. Since both electromagnetic actuators are energized simultaneously in this case, the magnetic force at the beginning of the opening process is about 22%, while in the case of a single coil it is only 13%. At the stroke stop H, curve K2 has a value of about 170%, and is therefore significantly greater than in the case of a single coil.

[0046] exist Figure 3The same diagram is shown in , which shows a comparison of the valve needle accelerations. In this case, the curve K1 defines a value of 100% at the stroke stop H. The curve K2 in the case of two electromagnetic actuators with the same stroke has a value of 120% in this case.

[0047] exist Figure 4 A comparison of the valve needle speeds is shown in . The curve K1 for a single coil again defines a comparison value of 100% at the stroke stop H. The curve K2 in the case of two electromagnetic actuators with the same stroke has here approximately 150%.

[0048] exist Figures 2 to 4 An example is also shown by the curve K3 in which the first armature stroke of the first electromagnetic actuator is greater than the second armature stroke of the second electromagnetic actuator. Here, the stroke of the second electromagnetic actuator is approximately 280 μm, which starts from a starting point at 500 μm and ends at approximately 220 μm. In this embodiment with different armature strokes, the energization of the second electromagnetic actuator is limited at the stroke stop II for the second electromagnetic actuator. Subsequently, only the first electromagnetic actuator is energized, wherein, Figure 2 and Figure 3 The curves in the figure show here the jump in the magnetic force ( Figure 2 ) and the jump in the acceleration of the valve needle ( Figure 3 ), Figure 4 The slope change in the speed of the valve needle 3 is shown.

[0049] As from Figures 2 to 4 It can be seen that the configuration of the gas injector according to the invention and the configuration of the method according to the invention generally provide better performance in gas injectors with the same armature stroke height and in gas injectors with different armature stroke heights than in the case of an electromagnetic actuator with only one coil as in the prior art. Although the total length of the gas injector 1 is increased by the series connection of the two electromagnetic actuators 10, 20 compared to a gas injector with only one electromagnetic actuator, the opening force provided by the series connection of the two electromagnetic actuators 10, 20 is significantly greater. Since the installation space length is less important than the increase in diameter (the diameter must be increased when using only one electromagnetic actuator to obtain the same performance as in the case of the sequential connection of two electromagnetic actuators), the present invention has a clear advantage over simply increasing the only electromagnetic actuator.

[0050] By various control methods, the braking process can also be achieved before the corresponding end position of the valve needle 3 during the opening process and the closing process, thereby reducing the impact during the opening process and the closing process at the corresponding stop or sealing seat, thereby significantly extending the service life of the components. The noise performance during operation can also be improved.

Claims

1. A gas injector for blowing a gaseous medium, the gas injector comprising: A closing element (2) having a valve needle (3) which releases at a sealing seat (6) and closes a gas path (8); An actuator for operating the closing element (2), wherein the actuator comprises a first electromagnetic actuator (10) and a second electromagnetic actuator (20), The first electromagnetic actuator (10) comprises a first coil (11), a first inner pole (12) and a first armature (13), and the second electromagnetic actuator (20) comprises a second coil (21), a second inner pole (22) and a second armature (23), and wherein the first electromagnetic actuator (10) and the second electromagnetic actuator (20) are arranged in series with each other along the axial direction (XX) of the gas injector; and A control unit (100) is configured to control the first electromagnetic actuator (10) and the second electromagnetic actuator (20).

2. The gas injector according to claim 1, wherein: The first electromagnetic actuator (10) has a first armature column (14), which is fixedly connected to the first armature (13) and operatively connected to the valve needle (3), and the second electromagnetic actuator (20) has a second armature column (24), which is connected to the second armature (23), and the second armature column (24) is operatively connected to the first armature column (14).

3. The gas injector according to claim 1 or 2, wherein: The first coil (11) and the second coil (21) are arranged on a common winding carrier (80).

4. A gas injector according to any one of the preceding claims, wherein: The first coil (11) and the second coil (21) are wound as a set and have an even number of layers.

5. The gas injector according to claim 3, wherein: The first coil (11) and the second coil (21) have separate windings, wherein the control unit (100) is configured to control the first coil (11) and the second coil (21) separately.

6. A gas injector according to any one of the preceding claims, wherein: A first armature stroke (H1) of the first armature (13) is greater than a second armature stroke (H2) of the second armature (23).

7. The gas injector according to claim 6, wherein: The first armature stroke (H1) is approximately 480 μm, and the second armature stroke (H2) is approximately 280 μm.

8. A gas injector according to any one of the preceding claims, wherein: A guide element (9) is arranged between the first electromagnetic actuator (10) and the second electromagnetic actuator (20) along the axial direction (XX) of the gas injector, wherein the guide element (9) guides both the first armature pin (14) and the second armature pin (24).

9. A method for operating a gas injector according to one of the preceding claims, wherein: During the opening process of the gas injector, the control unit (100) controls the first electromagnetic actuator (10) and the second electromagnetic actuator (20) so that the first electromagnetic actuator (10) and / or the second electromagnetic actuator (20) are turned off before reaching a complete stroke.

10. The method according to claim 9, wherein: The control unit (100) is configured to control the first electromagnetic actuator (10) and / or the second electromagnetic actuator (20) during a closing process so that the closing element (2) is actively braked.

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