Injection valve

Abstract

In order to increase the service life of an injection valve comprising an armature assembly consisting of a solenoid armature, a valve plate and a spring plate, it is provided that a spring element (34) is positioned in the armature assembly (6) axially between the solenoid armature (4) and the spring plate (33) and / or axially between the spring plate (33) and the valve plate (3) and axially pushes apart the solenoid armature (4) and the spring plate (33) or the spring plate (33) and the valve plate (3) in order to generate an axial preload force (FV).

Description

[0001] injection valve

[0002] The present application relates to an injection valve comprising a housing with a valve seat and a valve plate cooperating with the valve seat to open and close the injection valve, wherein the valve plate is connected to a magnet armature and a spring plate is arranged between the valve plate and the magnet armature, and the valve plate, the magnet armature and the spring plate form an armature assembly, wherein the magnet armature cooperating with an electromagnet in the injection valve to move the armature assembly to lift the valve plate from the valve seat to open the injection valve, wherein a gas volume is provided in the injection valve, which is connected to an inflow opening of the injection valve, and the valve seat at least partially delimits the gas volume in the injection valve, and at least one throughflow opening is provided in the valve seat,which, when the valve plate is lifted from the valve seat, connects the gas volume with an outlet opening of the injection valve and the valve plate closes at least one flow opening when the valve plate rests on the valve seat.

[0003] In gas engines with gaseous fuel, such as natural gas (compressed natural gas, CNG) or hydrogen, port fuel injection is often used using a port fuel valve. The gaseous fuel is injected at existing pressure into the intake manifold leading to the cylinder of the combustion engine or into the intake tract via the injection valve. The injection valve is supplied with fuel at a predetermined pressure by a fuel distribution system (fuel rail). The advantage of port fuel injection over direct injection into the cylinder is the lower injection pressure of the gaseous fuel, typically 0 to 30 bar differential pressure to the ambient air, which allows the components of the fuel supply to be designed more simply. The injection, and in particular the quantity of gaseous fuel, is controlled by a control unit, in particular via the opening time of the injection valve.This allows the amount to be precisely metered. The main requirements for an injection valve are a high mass flow rate to enable the required gas quantities to be delivered within the shortest possible opening times. Equally important is the wear resistance of the injection valve due to the very high switching frequency and switching load in order to achieve a sufficient service life for the injection valve. This presents a significant challenge, particularly with oil-free gaseous fuels such as hydrogen, which do not lubricate the valve components. Equally important is the lowest possible leakage of the injection valve in order to at least largely prevent the gaseous fuel from escaping when the injection valve is closed. Such injection valves are known from the prior art. WO 2022 / 180593 A1 shows an electromagnetically operated injection valve. A valve plate, which interacts with a valve seat, is arranged on a magnet armature.When the electromagnet is activated, the magnet armature is attracted to the valve plate and the valve plate lifts off the valve seat. When the magnet armature is deactivated, the magnet armature and valve plate are pressed against the valve seat by a spiral spring and the injection valve closes. The magnet armature and valve plate are guided in the injection valve via a spring plate. The spring plate is held at its radially outer edge in the housing of the injection valve. The magnet armature, valve plate and spring plate are firmly connected to one another and form an armature assembly. For this purpose, the magnet armature and spring plate are first joined together in the central area using a rivet. The plastic valve plate is then injection-molded onto the spring plate on the side of the spring plate. The production of the armature assembly is therefore very complex.US 2019 / 0368457 A1 also shows an injection valve with an armature assembly consisting of a rigidly connected magnet armature, valve plate and spring plate in between.

[0004] There are also injection valves in which the valve plate and the magnet armature are bolted together. An example of this can be found in WO 2015 / 144341 A1.

[0005] The moving parts of an injection valve and the stationary parts of an injection valve that come into contact with a moving part during operation of the injection valve are highly stressed components. This is due, on the one hand, to the very high speeds of the moving parts, which result from the required short opening and closing times. Due to the high speeds, high impact loads occur due to the moving part (e.g. the valve plate or the magnet armature) striking a stationary part (e.g. the valve seat or an armature stop). On the other hand, due to the application, injection valves are actuated a large number of times per second. Depending on the speed of the combustion engine, the injection valve can be actuated in the order of one to ten times per second; actuations with switching frequencies in the range of 1 Hz to 25 Hz are typical.Even more challenging, however, is the required service life of such injection valves. Often, several hundred million load cycles are required for the service life of the injection valve. These high and very frequent loads particularly affect an otherwise permanently connected armature assembly consisting of the magnet armature and valve plate, possibly also with a spring plate. As a result of these loads, however, the individual parts of the armature assembly can become loose and begin to move relative to each other. Such relative movements significantly increase wear in the injection valve, especially in the armature assembly, and can lead to rapid and premature failure of the injection valve.

[0006] It is an object of the present invention to provide an injection valve with an armature assembly consisting of a magnet armature, valve plate and spring plate with an increased service life.

[0007] This task is achieved by arranging a spring element in the armature assembly axially between the magnet armature and the spring plate and / or axially between the spring plate and the valve plate. This spring element axially pushes the magnet armature and the spring plate or the spring plate and the valve plate apart to generate an axial preload force. The preload force exerted by the spring element prevents the components of the armature assembly from becoming loose due to the applied load and prevents relative movement between these components, which would significantly increase wear in the armature assembly and shorten the service life of the injection valve.

[0008] If a washer is arranged axially between the solenoid armature and the spring element and / or axially between the valve plate and the spring element in the armature assembly, the localized load generated by the spring element can be better absorbed and distributed on the valve plate and / or the solenoid armature. This also helps reduce wear on the injection valve and increase its service life.

[0009] The magnetic plate is preferably connected to the valve plate by an interference fit between a pin on the magnetic plate or the valve plate and a recess on the valve plate and / or the magnetic plate. The pin can also be designed as a separate component or as a pin with a shoulder at one axial end. Instead of an interference fit, a thread can also be provided.

[0010] The spring plate can be advantageously secured in the injection valve by clamping a radially outer edge of the spring plate into the housing. This ensures a defined position of the spring plate. The radially outer edge of the spring plate can be at least partially bonded to the housing. By clamping the radially outer edge of the spring plate in the housing, possibly with an additional bonded connection, the radially outer edge of the spring plate cannot loosen due to possible settling caused by the load during operation. This also contributes to increasing the service life of the injection valve.

[0011] The present invention will be explained in more detail below with reference to Figures 1 to 3, which show exemplary, schematic, and non-limiting advantageous embodiments of the invention. Figure 1 shows an injection valve according to the invention,

[0012] Fig.2 an armature assembly according to the invention and

[0013] Fig.3 is an exploded view of an armature assembly according to the invention.

[0014] An injection valve 1 according to the invention, as shown in Fig. 1, has a valve seat 2 and a valve plate 3 which interacts with the valve seat 2 to open and close the injection valve 1. The valve plate 3 can be moved back and forth in the injection valve 1 between a closed position in which the valve plate 3 rests against the valve seat 2 in the axial direction (shown in Fig. 1), and an open position in which the valve plate 3 is lifted away from the valve seat 2 in the axial direction. The axial direction corresponds to the direction of movement of the valve plate 3. In order to move the valve plate 3, it is connected to a magnet armature 4. A spring plate 33 is arranged between the valve plate 3 and the magnet armature 4. The valve plate 3, the magnet armature 4 and the spring plate 33 form an armature assembly 6. The valve plate 3 and the magnet armature 4 are moved together with the armature assembly 6.During operation of the injection valve 1, the magnet armature 4 interacts with an electromagnet 5 in the injection valve 1 to move the armature assembly 6 by energizing the electromagnet 5. An electrical connection required for the operation of the electromagnet 5 is not shown in Fig. 1 and is also not relevant to the invention.

[0015] The injection valve 1 also contains a gas volume 7, which is connected to an inlet opening 8 of the injection valve 1. During operation of the injection valve 1, a gaseous medium is fed into the gas volume 7 via the inlet opening 8. The gas volume 7 is at least partially delimited by the valve seat 2, in the exemplary embodiment shown in Fig. 1, in the axial direction. The gas volume 7 in the injection valve 1 is otherwise delimited by the housing 11 of the injection valve 1 and the electromagnet 5, and / or by other components of the injection valve 1. At least one flow opening 10 is provided in the valve seat 2, which, when the valve plate 3 is lifted off the valve seat 2, connects the gas volume 7 to an outlet opening 9 of the injection valve 1. The valve plate 3 closes the at least one flow opening 10 when the valve plate 3 rests against the valve seat 2.When the injection valve 1 is open, i.e. when the valve plate 3 is lifted from the valve seat 2, a flow channel is created from the inlet opening 8, via the gas volume 7 and the at least one flow opening 10 to the outlet opening 9. When the injection valve 1 is closed, this flow channel is interrupted.

[0016] The individual parts and components of the injection valve 1 are arranged in a housing 11. The housing 11 is preferably constructed in multiple parts for manufacturing and assembly reasons. By controlling the opening time of the injection valve 1 and the predetermined, known gas pressure of the gaseous medium, the amount of gaseous medium discharged through the outlet opening 9 can be precisely controlled.

[0017] The spring plate 33 is advantageously clamped at its radially outer region in the housing 11 of the injection valve 1. For this purpose, the housing 11 is advantageously designed in at least two parts. The radially outer region of the spring plate 33 can also be integrally connected to the housing 11, for example by gluing or welding. The spring plate 33 thus supports and holds the armature assembly 6 in the injection valve 1. The spring plate 33 centers the armature assembly 6, and in particular the valve plate 3, and enables the axial reciprocating movement of the armature assembly 6 in the injection valve 1. At the same time, the spring plate 33 generates a spring force that presses the valve plate 3 against the valve seat 2 when the injection valve 1 is closed. The spring plate 9 can consist of a radially outer ring and a radially inner ring, which are connected to one another by several spring arms (as shown in Fig. 3).

[0018] However, an additional spring can also be provided between the electromagnet 5 and the magnet armature 4 to increase the spring force for keeping the injection valve 2 closed. This additional spring can also primarily apply the spring force for keeping the injection valve 1 closed.

[0019] It is not a primary concern of the invention how the valve plate 3, the magnet armature 4, and the spring plate 33 are connected to form the armature assembly 6. For example, the valve plate 3 and the magnet armature 4 could be screwed together, with the spring plate 33 being axially clamped and held between the two parts during screwing. However, it is also conceivable to connect the valve plate 3 and the magnet armature 4, along with the spring plate 33 arranged axially therebetween, by means of an interference fit.

[0020] In order to prevent the components of the armature assembly 6 from becoming loose during operation of the injection valve 1 and starting to move relative to one another, a spring element 34 is arranged axially between the magnet armature 4 and the spring plate 33 (as in Fig. 1) or axially between the valve plate 3 and the spring plate 33 (as in Fig. 2), or at both locations, which spring element 34 axially presses the magnet armature 4 and the spring plate 33 or the valve plate 3 and the spring plate 33 apart in order to generate a preload force Fv in the axial direction in the armature assembly 6. This preload force counteracts the components of the armature assembly 6 from becoming loose. Due to the small amount of space available for the armature assembly 6 in the injection valve 1, the spring element 34 is advantageously designed as a disc spring, which requires very little axial space and is adjustable in diameter.The spring element 34 can also be formed from several disc springs, for example as a disc spring package, or can be realized with other springs.

[0021] In the design of the armature assembly 6 according to Fig. 1, the valve plate 3 and the spring plate 33 are placed on a pin 35 of the magnet armature 4, with the spring plate 33 being arranged between the magnet armature 4 and the valve plate 3. In the illustrated design, the pin 35 and the valve plate 3 are held together by an interference fit. For this purpose, the valve plate 3 and the spring plate 33 have a central recess 36 through which the pin 35 is axially inserted. The pin 35 could also be designed as a threaded pin with an external thread, and the recess in the valve plate 3 as a bore with an internal thread that is screwed onto the external thread. The pin 35, optionally with an external thread, could also be arranged on the valve plate 3, and the recess 36, optionally with an internal thread, on the magnet armature 4.

[0022] Fig. 2 shows an armature assembly 6 according to the invention on an enlarged scale and in a further embodiment. Fig. 3 shows this armature assembly 6 in an exploded view. In this embodiment, the pin 35 is designed as a separate component and is not part of the magnet armature 4 or the valve plate 3. In this embodiment, a central recess 36 is provided on the valve plate and a further central recess 37 is provided on the magnet armature 4. The spring element 34 and the spring plate 9, and optionally also a spacer disk 38, also have corresponding central recesses. The pin 35 is inserted through the recess 36 in the valve plate 3, through the central recesses of the spring element 34 and the spring plate, and optionally also the spacer disk 38, and is inserted into the recess 37 on the magnet armature 4.The pin 35 forms an interference fit with the magnet armature 4, and the valve plate 3 is held by a shoulder 39 at one axial end of the pin 35. The pin 35 can also be inserted the other way around, with the shoulder 39 abutting the magnet armature 4, thus creating an interference fit between the pin 35 and the valve plate 3. The pin 35 can also be designed without a shoulder 39, in which case an interference fit is provided between the pin 35 and the magnet armature 4 and between the pin 35 and the valve plate 3. The spring plate 33 is again arranged axially between the valve plate 3 and the magnet armature 4.

[0023] Instead of an interference fit, a thread could again be provided between pin 35 and magnet armature 4 and / or between pin 35 and valve plate 3. For this purpose, corresponding external threads would be provided on pin 35 and internal threads on magnet armature 4 and / or on valve plate 3. For a pin 35 with a shoulder 39, the external thread would be provided on the axial end of pin 35 opposite shoulder 39. For a pin 35 as a standalone component, one axial end could be designed as an external thread and the other axial end for an interference fit. In every design, pin 35 passes through a central recess on spring plate 33.

[0024] In the embodiment of Fig. 2 and Fig. 3, the spring element 35, here a disc spring, is arranged axially between the spring plate 33 and the valve plate 3. In addition, in this embodiment, a spacer washer 38 is arranged axially between the spring element 35 and the valve plate 3, so that the spring element 35 axially rests against the spacer washer 38 and the spacer washer 38 axially rests against the valve plate 3. Such a spacer washer 38 can be advantageous if the valve plate 3 is made of plastic and the spring force of the spring element 35 could damage the plastic valve plate 3, at least over time. A spacer washer 38 can alternatively or additionally also be provided between the spring element 35 and the magnet armature 4 or the spring plate 33 and the magnet armature 4.

[0025] In a further advantageous embodiment, another spring element, such as a disc spring, could also be arranged between the housing 11 and the outer edge of the spring plate 33, with which the spring plate 33 is clamped in the housing. This spring element can also serve to prevent any possible loosening of the spring plate 33 at the clamping point on the housing 11 by applying a preload force. A clamping ring can also be arranged between the spring element and the housing.

[0026] Fig. 1 shows that the valve seat 2 is advantageously inserted into the housing 11 and axially abuts a projection 40 of the housing 11. The projection 40 could also be designed as a ring inserted into the housing 11. The valve seat 2 can be pressed and held against the projection 40 by the differential pressure acting between the pressure of the supplied gaseous medium and the pressure acting at the outlet opening 9.

[0027] A further advantageous, optional feature of an injection valve 1 according to the invention is an opening stop 42, against which the magnet armature 4 strikes at the end of the opening movement. The opening stop 42 thus limits the opening movement of the armature assembly 6 when the injection valve 1 opens. In the embodiment according to Fig. 1, such an opening stop 42 is provided. In this embodiment, the opening stop 42 is arranged radially between the housing 11 and the electromagnet 5. The opening stop 42 can, of course, also be arranged elsewhere. To minimize wear, favorable material combinations of the magnet armature 4 and the opening stop 42 can also be provided. The magnet armature 4 will be made of a metal, which means that a suitable impact-resistant plastic is suitable for the opening stop 42.It can also be provided that the magnet armature 4 is surface-treated in the area of ​​the opening stop 42 in order to increase the fatigue strength of the magnet armature 4 against the numerous impacts that occur when opening the injection valve 1. The surface treatment can be carried out as nitriding to form a nitrite layer or as a hard material coating.

Claims

Patent claims 1 . Injection valve with a housing (11) and with a valve seat (2) and a valve plate (3) cooperating with the valve seat (2) for opening and closing the injection valve (1), wherein the valve plate (3) is connected to a magnet armature (4) and a spring plate (33) is arranged between the valve plate (3) and the magnet armature (4), and the valve plate (3), the magnet armature (4) and the spring plate (33) form an armature assembly (6), wherein the magnet armature (4) cooperating with an electromagnet (5) in the injection valve (1) to move the armature assembly (6) in order to lift the valve plate (3) from the valve seat (2) for opening the injection valve (1), wherein a gas volume (7) is provided in the injection valve (1), which is connected to an inflow opening (8) of the injection valve (1), and the valve seat (2) the gas volume (7) in the injection valve (1) is at least partially limited and at least one flow opening (10) is provided in the valve seat (2),which, when the valve plate (3) is lifted from the valve seat (2), connects the gas volume (7) to an outflow opening (9) of the injection valve (1), and the valve plate (3) closes the at least one throughflow opening (10) when the valve plate (3) rests against the valve seat (2), characterized in that a spring element (34) is arranged in the armature assembly (6) axially between the magnet armature (4) and the spring plate (33) and / or axially between the spring plate (33) and the valve plate (3), which spring element axially presses the magnet armature (4) and the spring plate (33) or the spring plate (33) and the valve plate (3) apart to generate an axial preload force (Fv).

2. Injection valve according to claim 1, characterized in that a spacer disc (38) is arranged in the armature assembly (6) axially between the magnet armature (4) and the spring element (34) and / or axially between the valve plate (3) and the spring element (34).

3. Injection valve according to claim 1 or 2, characterized in that a pin (35) is provided on the magnet armature (4), which is arranged in a recess (36) of the valve plate (3) to form a press fit, or a pin is provided on the valve plate (3) (35) is arranged, which is arranged in a recess (37) on the magnet armature (4) to form a press fit.

4. Injection valve according to claim 1 or 2, characterized in that a pin (35) with an external thread is provided on the magnet armature (4), which is inserted in a recess (36) of the valve plate (3) is screwed with an internal thread or a pin (35) with an external thread is arranged on the valve plate (3), which is screwed into a recess (37) on the magnet armature (4) with an internal thread.

5. Injection valve according to claim 1 or 2, characterized in that a separate pin (35) is provided, which is designed to form a press fit in a recess (36) on the valve plate (3) and to form a press fit in a recess (37) is arranged in the magnet armature (4).

6. Injection valve according to claim 1 or 2, characterized in that a separate pin (35) is provided, which is arranged with a first external thread in a recess (36) on the valve plate (3) with an internal thread and which is arranged with a second external thread in a recess (37) in the magnet armature (4) with an internal thread.

7. Injection valve according to claim 1 or 2, characterized in that a separate pin (35) with a shoulder (39) is provided at one axial end of the pin (35), which is arranged in a recess (36) on the valve plate (3) to form an interference fit, wherein the shoulder (39) bears against the magnet armature (4) or is arranged in a recess (37) on the magnet armature (4) to form an interference fit, wherein the shoulder (39) bears against the valve plate (3).

8. Injection valve according to claim 1 or 2, characterized in that a separate pin (35) with a shoulder (39) at one axial end of the pin (35) and an external thread at the opposite axial end of the pin (35) is provided, wherein the pin (35) is screwed into a recess (36) on the valve plate (3) with an internal thread and the shoulder (39) rests on the magnet armature (4) or the pin (35) is screwed into a recess (37) on the magnet armature (4) with an internal thread and the shoulder (39) rests on the valve plate (3).

9. Injection valve according to one of claims 1 to 8, characterized in that a radially outer edge of the spring plate (33) is clamped in the housing (11).

10. Injection valve according to claim 9, characterized in that the radially outer edge of the spring plate (33) is at least partially materially connected to the housing (11).

11. Injection valve according to one of claims 1 to 10, characterized in that an opening stop (42) is provided in the housing (11), against which the magnet armature (4) rests when the injection valve (1) is open, and the magnet armature (4) is surface-treated in the region of the opening stop (42).

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