DE102020215866A1 - Gas injector for injecting gaseous fuel - Google Patents

Abstract

The present invention relates to a gas injector for blowing in a gaseous medium, comprising a main valve (2) with a first hollow valve needle (20) which opens and closes a first fluid path (22) at a first sealing seat (21), a control valve (3) with a second hollow valve needle (30) which opens and closes a second fluid path (32) at a second sealing seat (31), the first valve needle (20) and the second valve needle (30) being arranged so as to be movable in the axial direction (X-X) of the gas injector and the first sealing seat (21) is formed between the first valve needle (20) and the second valve needle (30) and the second sealing seat (31) is formed between the second valve needle (30) and a housing part (5), a magnetic actuator ( 4) having an armature (40), the armature (40) being fixedly connected to the second valve needle (30) in order to open the second valve needle (30), and a first restoring element (6) for restoring the first Ve valve needle (20) and a second restoring element (7) for restoring the second valve needle (30), the first restoring element (6) being arranged between the first valve needle (20) and the second valve needle (30) and the first valve needle (20) biases against the second valve needle (30).

Description

State of the art

The present invention relates to a gas injector for injecting gaseous fuel, in particular natural gas or hydrogen, and a gas internal combustion engine with such a gas injector.

Gas injectors for blowing in gaseous fuel are known from the prior art in different configurations. One difference between gas injectors and injectors for liquid fuel is that large opening cross sections are required to inject large amounts of fluid. In the case of gas injectors, this must be achieved by large opening cross sections. Another difference to liquid fuels is that gaseous fuels are often stored in the vehicle under very high pressure. Because of these high gas pressures, however, actuators for opening the gas injector must be designed to be large, which would lead to a very large actuator that would take up installation space, particularly when using magnetic actuators. From the DE 10 2013 222 025 A1 a gas injector with a servo valve is also known, which shows improved opening behavior. In this case, however, it would be desirable for an actuator force to be able to be further reduced, as a result of which a gas injector with a smaller installation space would be possible.

Disclosure of Invention

In contrast, the gas injector according to the invention, in particular for blowing in natural gas or hydrogen, with the features of claim 1 has the advantage that an opening force can be further reduced in comparison with the prior art. As a result, a magnetic actuator, which is used to open the gas injector, can be further reduced in terms of its installation space. In this way, in particular, an outer diameter of the gas injector can be further reduced. According to the invention, this is achieved in that the gas injector has a main valve and a control valve. The main valve includes a first hollow valve needle, which opens and closes a first fluid path at a first sealing seat. The control valve includes a second hollow valve needle which opens and closes a second fluid path at a second sealing seat. The first valve needle is movably arranged in the second valve needle in the axial direction. The first sealing seat is also formed between the first and the second valve needle. The second sealing seat is formed between the second valve needle and a housing component. A magnetic actuator with an armature is provided as the actuator, with the second valve needle being connected to the armature of the magnetic actuator in order to open the second valve needle. Furthermore, a first and a second restoring element are provided. The first restoring element is set up to reset the first valve needle and the second restoring element is set up to reset the second valve needle. Furthermore, the first restoring element is arranged between the first and second valve needles and biases the first valve needle against the second valve needle.

The main valve can now be opened by opening the control valve, which only has to perform a small stroke. Since the first restoring element pretensions the first valve needle in relation to the second valve needle, only the spring force of the second restoring element on the armature has to be overcome in order to open the control valve. As a result, the magnet actuator can be made smaller. Furthermore, a compact and weight-reduced construction of the first restoring element is possible.

The dependent claims show preferred developments of the invention.

The gas injector further preferably comprises a throttle disk with a throttle point which lies in a through-opening through the throttle disk. The throttle disk allows a simple implementation of a control chamber to open the control valve.

More preferably, the gas injector comprises a holder which is fixedly connected to the throttle disk and fixedly connected to the first valve needle. As a result, the first valve needle, the holder and the throttle element move together. The connection between the components can be provided, for example, via welding or tacking or clips or as a press connection or crimping or soldering. The first restoring element is particularly preferably supported between the holder and the second valve needle. This configuration allows the first sealing seat on the main valve to be closed very quickly when the gas injector is returned to a closed initial position.

The first valve needle, the holder and the throttle disk preferably define a spring space for accommodating the first restoring element. The second valve needle is more preferably axially movable together with the throttle disk.

The first valve needle is preferably arranged at least partially in the second valve needle. As a result, a very compact and space-saving design can be implemented. Furthermore can as a result, when the gas injector is open, the gas to be blown in can be passed centrally through the first hollow valve needle.

According to a further preferred embodiment of the invention, the gas injector also includes a first and a second sealing element on the throttle disk. The first sealing element is arranged on an inner circumference of the throttle disk for sealing on the second valve needle. The second sealing element is arranged on an outer circumference of the throttle disk for sealing on a housing component of the gas injector.

More preferably, the first and second valve needles are each outwardly opening valve needles. As a result, the opening process can be further simplified by means of the control valve.

The first restoring element is more preferably a conical spring. The conical spring preferably acts on a free end of the second valve needle.

More preferably, the first valve needle and the second valve needle each have annular flange areas on their injection-side ends, between which the first valve seat is formed.

Furthermore, the present invention relates to a gas internal combustion engine with a gas injector according to the invention.

character list

• 1 eine schematische Schnittansicht eines Gasinjektors gemäß einem ersten Ausführungsbeispiel der vorliegenden Erfindung im geschlossenen Zustand,
• 2 bis 5 schematische Schnittansichten des Gasinjektors von 1, welche einen Öffnungsvorgang und eine Schließvorgang des Gasinjektors darstellen,
• 6 eine schematische Schnittansicht eines Gasinjektors eines zweiten Ausführungsbeispiels im geschlossenen Zustand,
• 7 eine schematische Schnittansicht eines Gasinjektors eines dritten Ausführungsbeispiels im geschlossenen Zustand, und
• 8 eine schematische Schnittansicht eines Gasinjektors eines vierten Ausführungsbeispiels im geschlossenen Zustand.

Preferred embodiments of the invention are described in detail below with reference to the accompanying drawings. In the drawing, identical or functionally identical parts are denoted by the same reference symbols. In the drawing is:

• 1 a schematic sectional view of a gas injector according to a first embodiment of the present invention in the closed state,
• 2 until 5 schematic sectional views of the gas injector from 1 , which represent an opening process and a closing process of the gas injector,
• 6 a schematic sectional view of a gas injector of a second embodiment in the closed state,
• 7 a schematic sectional view of a gas injector of a third embodiment in the closed state, and
• 8th a schematic sectional view of a gas injector of a fourth embodiment in the closed state.

Preferred Embodiments of the Invention

In the following, with reference to the 1 until 5 a gas injector 1 according to a first preferred embodiment of the invention is described in detail.

How out 1 As can be seen, which shows the closed state of the gas injector 1, the gas injector 1 is arranged directly on a combustion chamber 12 in order to blow a gaseous medium into the combustion chamber of a gas internal combustion engine.

The gas injector 1 includes a main valve 2, a control valve 3 and a magnetic actuator 4. The magnetic actuator 4 includes an armature 40, a coil 41 and an inner pole 42. Reference number 43 designates a magnetic yoke.

The solenoid actuator 4 actuates the control valve 3, as a result of which the gas injector 1 can then be opened completely by opening the main valve 2.

The main valve 2 closes the gas injector at a first sealing seat 21. The control valve 3 opens and closes the gas injector at a second sealing seat 31.

The main valve 2 includes a first, hollow valve needle 20 which extends axially through most of the gas injector. An outwardly directed flange 25 is provided on an injection-side end of the first valve needle 20 .

The control valve 3 comprises a second, hollow valve needle 30 and a second flange 35.

The first valve needle 20 is arranged in the second valve needle 30 in an axially displaceable manner. The second valve needle 30 is also arranged in the gas injector 1 in an axially displaceable manner.

How further from 2 As can be seen, the second valve needle 30 is firmly connected to the armature 40 of the magnet actuator 4 . This is preferably achieved using a number of spot welds.

A first fluid path 22 for the fluid to be injected runs through the first hollow valve needle 20 and defines a main path for the fluid. A second fluid path 32 runs from a control chamber 10 through a gap 44 between the armature 40 and the second hollow valve needle 30 and runs along the outer circumference of the second valve needle 30 to to the flange 35 of the second valve needle 30 on the second sealing seat 31.

How out 1 As can be seen, the first sealing seat 21 is formed between the flange 25 on the first valve needle 20 and the flange 35 on the second valve needle 30 .

The gas injector 1 also includes a first restoring element 6 and a second restoring element 7. The first restoring element 6 is provided for restoring the first valve needle 20 and the second restoring element 7 uses the armature 40 to return the second valve needle 30 to the closed initial state. How out 1 As can be seen, the second restoring element 7 is arranged between the stationary inner pole 42 and the armature 40 .

The gas injector 1 also includes a throttle disk 8 which has a throttle 80 in a through-opening 81 . The through opening 81 connects an inlet 13 of the gaseous medium to the control chamber 10. The throttle disk 8 is arranged so that it can move relative to a housing component 15 of the gas injector and is also arranged so that it can move relative to the second valve needle 30 in the axial direction X-X.

How further from 1 As can be seen, the throttle disk 8 is firmly connected to a holder 9, for example via welded joints. The holder 9 is in turn firmly connected to the first valve needle 30, for example also via welded joints. The first valve needle 20, the throttle disk 8 and the holder 9 define a spring chamber 60 in which the first restoring element 6 is arranged. How out 1 As can be seen, the first restoring element 6 is a conical spring which is supported on the one hand on the holder 9 and on the other hand on a free end of the second valve needle 30 . The first restoring element 6 thus biases the first and second valve needles 20, 30 against one another.

The function of the gas injector 1 according to the first exemplary embodiment is as follows. Starting from the closed state in 1 the magnetic actuator 4 is activated. As a result, the armature 40 is pulled against the inner pole 42 and an armature path 11 is overcome, which in 2 is indicated by the arrow A. Since the armature 40 is connected to the second valve needle 30, the control valve 3 opens. The opening stroke H1 of the control valve 3 corresponds to the armature travel 11. The second restoring element 7 is pretensioned. The first valve needle 20 initially remains immobile.

By opening the control valve 3, pressurized gaseous medium that was in the control chamber 10 is forced via the second fluid path 32 into the combustion chamber 12, in which the pressure is lower than the pressure in the control chamber 10. this is in 2 indicated by the arrows 32. The fluid flow is as in 2 shown, on the outer circumference of the second valve needle 30.

To open the control valve 3, only the spring force of the second restoring element 7 has to be overcome. Here, the opening process of the control valve 3 is also supported by the high pressure in the control chamber 10, which is very much higher than the pressure currently prevailing in the combustion chamber 12.

However, the opening of the control valve now causes the pressure in the control chamber 10 to drop to approximately the pressure in the combustion chamber 12. As a result, the throttle disk 8, as in 3 indicated by the arrow C, towards the armature 40 moves. As a result, a volume of the control chamber 10 is reduced. Since the throttle disk 8 is firmly connected to the first valve needle 20 via the holder, this opens when the throttle disk 8 moves in the direction of the armature 40. This is in 3 indicated by the arrow D. The main valve 2 is thus opened by a stroke H2. The first fluid path 22 is thus free, so that the gaseous medium can be blown from the inlet 13 through the first hollow valve needle 20 via the opened first sealing seat 21 directly into the combustion chamber 12 . The magnetic actuator 4 remains activated during the blowing-in process.

In order to close the gas injector 1, the magnetic actuator 4 is now deactivated. As a result, the restoring force of the second restoring element 7 pushes the armature 40 back into its initial position, which 4 is indicated by the arrow E. Since the armature 40 is connected directly to the second valve needle 30, the second sealing seat 31 between the second valve needle 30 and the housing component 5 of the gas injector is closed (arrow F). During this process, however, the first sealing seat 21 remains open, so that gaseous medium still flows into the combustion chamber 12 via the first fluid path 22 .

Since the armature 40 is firmly connected to the second hollow valve needle 30, this is also moved in the axial direction towards the inlet 13. As a result, a force K is also exerted on the first restoring element 6, which then exerts a restoring force via the holder 9 on the throttle disk 8, which are also firmly connected to one another ( 5 ).

During the opening process, a fluid flow 82 also continuously exits through the throttle 80 into the control chamber 10, so that in the control chamber 10 the pressure slowly rises again to the starting pressure of the gaseous fuel. As a result, the volume of the control chamber 10 is increased again, as a result of which the movement of the throttle disk 8 in the direction of the inlet 13 is further supported.

This movement of the throttle disk 8 and the restoring force of the first restoring element 6 then also closes the first sealing seat 21 via the holder 9 and the first valve needle 20, which in 5 is indicated by the arrow G. The closing movements of the throttle disk 8, the holder 9 and the first valve needle 20, which are firmly connected to one another, are illustrated by the arrows G1, G2 and G3. The closing process is also supported by the first restoring element 6, so that the first sealing seat 21 can be closed securely.

Thus, first the control valve 3 and then the main valve 2 can be opened by means of a relatively small magnetic force by the magnetic actuator 4 . The amount of gaseous medium used to open the control valve 3 is blown into the combustion chamber 12 so that a return line of this gaseous medium used as a control medium can be dispensed with. The control quantity for opening control valve 3 is simply blown into combustion chamber 12 .

Since the gaseous fuel is under high pressure, which is always higher than a maximum pressure in the combustion chamber 12 both in the intake phase and in the compression phase of the gas internal combustion engine, a very long injection time is possible. This ensures that the required amounts of gaseous medium reach the combustion chamber 12 .

Since the main valve 2 and the control valve 3 are both designed as outwardly opening valves, a very simple and compact construction is possible. Due to the reduced required opening force, the magnetic actuator 4 can also be designed to be very small.

6 shows a gas injector 1 according to a second embodiment of the invention. Identical or functionally identical parts are denoted by the same reference symbols as in the first exemplary embodiment. In contrast to the first exemplary embodiment, the gas injector of the second exemplary embodiment additionally has a first seal 83 on the inner circumference of the restrictor disc 8 and a second seal 84 on the outer circumference of the restrictor disc 8 . Furthermore, a third seal 85 is provided between the first valve needle 20 and the second valve needle 30 . This achieves improved sealing between the components on the throttle disk 8 or between the first and second valve needles 20, 30, which results in higher switching forces. However, the seals 83, 84, 85 are preferably designed in such a way that as little friction as possible occurs when the individual components move relative to one another, as described in the first exemplary embodiment.

7 shows a gas injector 1 according to a third embodiment of the invention. Identical or functionally identical parts are denoted by the same reference symbols as in the first exemplary embodiment. In contrast to the first exemplary embodiment, the third exemplary embodiment has a modified throttle disk 8 . How out 7 can be seen, the throttle disk 8 is firmly connected directly to the first valve needle 20 . As a result, the holder 9 can be saved. In this way, in particular, a larger volume in the control chamber 10 is possible. By simply varying the volume of the control chamber 10, the switching time of the gas injector can be influenced in a simple manner. A larger volume of the control chamber 10 results in slightly longer switching times. A reduced volume of the control chamber 10 enables shorter switching times.

8th shows a gas injector 1 according to a fourth embodiment of the invention. Identical or functionally identical parts are in turn denoted by the same reference symbols as in the previous exemplary embodiments. How out 8th As can be seen, the fourth exemplary embodiment essentially corresponds to the first exemplary embodiment with holder 9. In contrast to this, however, a spring support 14 is provided. The spring support 14 is firmly connected to the armature 40 of the magnetic actuator 4 and is arranged on the outer circumference of the second valve needle 30 . The second restoring element acts on the spring support 14 . As a result, in particular, a larger diameter for the second restoring element 7 is possible. As a result, larger spring forces can be realized in a simple manner. The spring support 14 is preferably a sleeve and has a radially outwardly directed support flange 14a for the second restoring element 7 .

Thus, gas injectors 1 with reduced necessary magnet armature forces can be realized by the exemplary embodiments shown. In this case, a construction of the gas injectors 1 is nevertheless possible in a relatively simple manner.

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• DE 102013222025 A1 [0002]

Claims (11)

Gas injector for blowing in a gaseous medium, comprising: - a main valve (2) with a first hollow valve needle (20) which opens and closes a first fluid path (22) at a first sealing seat (21), - a control valve (3) with a second hollow valve needle (30) which opens and closes a second fluid path (32) at a second sealing seat (31), - wherein the first valve needle (20) and the second valve needle (30) are arranged to be movable in the axial direction (X-X) of the gas injector and the first sealing seat (21) is formed between the first valve needle (20) and the second valve needle (30) and the second sealing seat (31) is formed between the second valve needle (30) and a housing part (5), - A magnetic actuator (4) with an armature (40), the armature (40) being firmly connected to the second valve needle (30) in order to open the second valve needle (30), and - a first restoring element (6) for restoring the first valve needle (20) and a second restoring element (7) for restoring the second valve needle (30), - Wherein the first restoring element (6) is arranged between the first valve needle (20) and the second valve needle (30) and prestresses the first valve needle (20) against the second valve needle (30). gas injector after claim 1 , further comprising a throttle disk (8) with a throttle (80) which is arranged in a through opening (81) which leads through the throttle disk (8) in the axial direction, with a control chamber (10) between the armature (40) and the throttle disk (8) is formed. gas injector after claim 2 , wherein the throttle disc (8) is arranged to be movable in the axial direction (XX). gas injector after claim 2 or 3 , further comprising a bracket (9) which is fixed to the throttle disk (8) and fixed to the first valve needle (20), so that the bracket (9), the throttle disk (8) and the first valve needle (20) move as a unit in the axial direction. gas injector after claim 4 , wherein the first restoring element (6) is arranged between the holder (9) and the second valve needle (30). gas injector after claim 5 , wherein the first valve needle (20), the holder (9) and the throttle disk (8) define a spring chamber for receiving the first restoring element (6). Gas injector according to one of the preceding claims, wherein the first valve needle (20) is at least partially arranged in the second valve needle (30). A gas injector according to any one of the preceding claims, further comprising first and second sealing members (83, 84) on the orifice plate (8) to provide a seal at an inner periphery and an outer periphery of the orifice plate. Gas injector according to one of claims 2 until 4 , wherein the throttle disc (8) is firmly connected to the first valve needle (20). Gas injector according to one of the preceding claims, further comprising a spring support (14) which is arranged on the armature (40) and supports the second restoring element (7). Gas internal combustion engine comprising a gas injector according to any one of the preceding claims.

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