EP2634413B1 - Injector - Google Patents

Description

State of the art

The present invention relates to an injection valve for injecting a medium, in particular for injecting fuel into a combustion chamber.

The prior art knows various injection valves, in particular for fuel, wherein each injection openings are opened and closed by means of a valve needle. The valve needle is usually moved by means of an actuator against a closing spring, so that a desired amount of fuel is selectively introduced. Optionally, in the case of a solenoid valve, the magnet armature can be decoupled from the valve needle. In directly connected injectors, the closing spring force, the hydraulic force and the friction forces must be overcome to open the valve. In a solenoid valve, these closing forces must be applied by the electromagnet, which has a high electrical energy requirement. Solutions are known which divides the moving mass of the valve needle into several sub-masses, which are coupled to one another by means of springs, guides and stop surfaces. Furthermore, a hydraulic valve opening in common rail diesel injectors is known, but always have a return of the fuel to the tank. This return is expensive and maintenance-prone.

From the EP 1 602 821 A1 An injection valve, in particular for injecting fuel into a combustion chamber, is already known, which includes, inter alia, a housing with at least one injection opening on an outlet side. The injector further comprises a solenoid, a magnet armature linearly movable by the solenoid, a linearly movable valve needle for opening and closing the injection port with a first stop on an outlet side of the magnet armature and a second stop on an outlet side of the armature, the magnet armature between the first Stop and the second stop relative to the valve needle is linearly movable, and wherein for the second stop a first stop surface and the first stop surface opposite the second stop surface are formed, wherein on the first stop surface designed as a cavity filled with the medium hydraulic cushion is arranged, and wherein the cavity is open on the side facing the second stop surface.

Disclosure of the invention

The injection valve according to the invention with the features of claim 1 uses a pressure difference between a magnet armature bottom and a top of the stop sleeve on the valve needle against the pressure on the underside of the stop sleeve, thereby the valve needle from the valve seat to lift. This reduces the energy required to open the injector. Furthermore, the pressure difference arising during a magnet armature movement between magnet armature and stop ring is used to dampen the valve needle movement. This results in a lower noise level and less wear of the injector. Furthermore, the magnetic armature movement can be selectively damped by the hydraulic cushion according to the invention after closing the valve needle. This reduces the risk of needle bouncers, in which the valve needle lifts after first closing again without renewed energization from the seat. In addition, the time is reduced until the armature reaches its original position again. As a result, the valve can be controlled faster than before so that it injects the desired amount. All these advantages are achieved by an injection valve for injecting a medium with the features of claim 1. In particular, it is a fuel injection valve for injecting fuel into a combustion chamber. This fuel injection valve is used in particular for the direct injection of fuel into a spark-ignited internal combustion engine. The injection valve comprises a housing with at least one injection opening on an outlet side. About this at least one injection port, the medium is injected, for example, in the combustion chamber. Furthermore, the injection valve comprises a magnetic coil, a magnet armature linearly movable armature and a linearly movable valve needle for opening and closing the injection opening. At this valve needle, a first stop on an outlet side facing away from the armature and a second stop on an outlet side facing the armature are formed. The magnet armature can move linearly between the first stop and the second stop with respect to the valve needle and with respect to the housing. Depending on the direction of movement of the armature takes over the first stop or on the second stop the valve needle. According to the invention, a hydraulic cushion is provided. This hydraulic cushion is designed as a cavity filled with the medium. For the stop of the magnet armature on the second stop, a first stop face and a first stop face opposite the second stop face are provided. One of the two stop surfaces is located on the armature. The other stop surface is located on the valve needle. At the first stop surface designed as a cavity hydraulic cushion is arranged. The cavity is open on the side facing the second stop surface. As the two abutment surfaces move toward each other, the pressure of the medium in this cavity increases and a force is created which counteracts the magnet armature movement. If the medium is then displaced out of the cavity by gaps, damping of the movement of the valve needle and / or of the magnet armature results. When the armature and the second stop move away from each other, a negative pressure in this cavity, whereby the second stopper and thus also the valve needle are pulled in the direction of the magnet armature.

The dependent claims show preferred developments of the invention.

It is preferably provided that the second stop and the first stop surface are formed with the cavity completely on the valve needle. In particular, the second stop is formed by a fixedly connected to the valve needle sleeve. Alternatively, the first stop surface with the cavity can also be formed on the magnet armature.

Furthermore, a shoulder is provided on the first stop surface. In particular, it is provided that the shoulder on the side facing the magnet armature of the second stop extends in the direction of the magnet armature so as to limit the cavity laterally. This shoulder is preferably formed completely on the second stop and spaced from the main body of the valve needle. This will open the cavity one side limited by the body of the valve needle and on the other side by this paragraph. The inclination of the magnet armature facing side of the second stopper relative to the longitudinal axis may be combined with the formation of this paragraph.

Furthermore, the second stop face, in particular on the magnet armature, is shaped such that it partially dips into the cavity during a movement of the valve needle and / or of the magnet armature. For this purpose, the paragraph on the second stop is formed so that it surrounds the armature at least partially laterally. In this case, a first, parallel to the longitudinal axis of the valve needle surface on the magnet armature and a second, parallel to the longitudinal axis of the valve needle surface on the second stop are provided. Between these two surfaces, a gap, in particular an annular gap, is formed. This gap is used for throttled feeding and discharging the medium from the cavity. Characterized in that the two surfaces are arranged parallel to each other, resulting in an independent of the relative position of the armature to the second stop constant throttle. If the second stop and the magnet armature move toward each other, the medium is forced out of the cavity via this gap. If the magnet armature and the second stop move away from each other, the medium is sucked into the cavity via this gap and the negative pressure is maintained for at least a certain time.

However, it is also possible to form a path-dependent gap between the two abutment surfaces, so that the corresponding throttling effect for the flow of the medium into the cavity and out of the cavity depends on the distance between the magnet armature and the second stop. Thus, a surface of the shoulder facing the magnet armature on the second stop serves as a path-dependent throttle for the medium which flows into and out of the cavity.

Furthermore, a first spring acting on the valve needle in the direction of the outlet and a second spring acting on the magnet armature in the direction of the outlet are provided. The first spring thus pushes the valve needle in its closed position. The second spring presses the armature in the direction of the second stop and thus also in the closing direction.

It is provided to connect a spring pot fixed to the armature on a side facing the outlet of the magnet armature. This spring cup engages under the second stop, so that the second spring can be supported with one end on the spring cup and with the other end on the outlet-facing side of the second stop.

Brief description of the drawings

Figur 1

ein erfindungsgemäßes Einspritzventil gemäß einem ersten Beispiel,

Figur 2

ein Diagramm zum erfindungsgemäßen Einspritzventil gemäß allen Ausführungsbeispielen,

Figur 3

das erfindungsgemäße Einspritzventil gemäß einem zweiten Beispiel,

Figur 4

das erfindungsgemäße Einspritzventil gemäß einem dritten Beispiel,

Figur 5

das erfindungsgemäße Einspritzventil gemäß einem vierten Beispiel, und

Figur 6

das erfindungsgemäße Einspritzventil gemäß einem Ausführungsbeispiel.

Hereinbelow, unclaimed examples and an embodiment of the invention will be described in detail with reference to the accompanying drawings. Showing:

FIG. 1

an inventive injection valve according to a first example,

FIG. 2

a diagram of the injection valve according to the invention according to all embodiments,

FIG. 3

the injection valve according to the invention according to a second example,

FIG. 4

the injection valve according to the invention according to a third example,

FIG. 5

the injection valve according to the invention according to a fourth example, and

FIG. 6

the injection valve according to the invention according to an embodiment.

Embodiments of the invention

FIG. 1 shows an injection valve 1 according to a first example, which does not belong to the claimed subject matter. Shown is the injection valve 1 in a section parallel to a longitudinal axis 7, wherein only one half of the rotationally symmetrical components of the injection valve 1 is shown.

The injection valve 1 comprises a housing 2 with at least one injection opening 16 on an outlet side 17. The outlet side 17 faces an outlet 18 facing away from the outlet. A fixed part of the housing 2 is a magnet pot 3. In this magnet pot 3, a magnetic coil 4 is arranged. Inside the housing 2 is a housing-fixed inner pole 5. At this inner pole 5, an adjusting sleeve 6 is attached.

In the housing 2, a relative to the housing 2 along the longitudinal axis 7 linearly movable armature 11 is arranged. About the magnetic coil 4 of the inner pole 5 is magnetized and thereby attracted to the armature 11 or repelled and thus moved along the longitudinal axis 7.

Furthermore, a valve needle 8 extending along the longitudinal axis 7 is located in the housing 2. The valve needle 8 is movable relative to the magnet armature 11 and relative to the counter housing 2. The valve needle 8 comprises an internally hollow body 9 with lateral passage openings 10 for the medium to be injected. Furthermore, a stop ring 12 and a stop sleeve 13 is firmly connected to the base body 9. The stop ring 12 represents a first stop 14. The stop sleeve 13 represents a second stop 15. The magnet armature 11 is movable between the two stops 14, 15 and thus takes over these two stops 14, 15 with the valve needle 8. Between the valve needle 8 and the injection port 16, a spherical closure body 20 is arranged. In the closed state, the valve needle 8 presses this closure body 20 onto the valve seat 21, which is embodied conically on the housing 2. The media flow through the spray opening is interrupted in the de-energized state.

Between the adjusting sleeve 6 and the stop ring 12, a first spring 24 is arranged. Between the armature 11 and the inner pole 5, a second spring 25 is arranged. The first spring 24 presses the valve needle 8 in the direction of the outlet side 17. The second spring 25 presses the armature 11 in the direction of the outlet side 17th

The closure body 20 forms, together with the lower part of the housing 2, a valve seat 21. In the lower region, a lower guide 22 is formed between the closure body 20 and the housing 2. In the upper part, the valve needle 8 is guided on the armature 11. This armature 11 in turn is guided over an upper guide 23 relative to the housing 2.

At the second stop 15 are a first stop surface, arranged on the stop sleeve 13, and a second stop surface, disposed on the armature 11, opposite. The first stop surface faces the magnet armature 11 and is inclined at an angle α with respect to the longitudinal axis 7. This angle α deviates from 90 °. The inclination is chosen so that on the magnet armature 11 facing side of the stop sleeve 13, a cavity 19 is formed. This cavity 19, filled with the medium to be injected, forms a hydraulic cushion.

If the magnetic coil 4 flows through current, a magnetic field builds up, as a result of which the magnet armature 11 is pulled against the inner pole 5. By the movement of the armature 11 in the liquid medium is formed between the armature 11 and the inner pole 5 is an over- and on the opposite side, a negative pressure against which the armature 11 must be moved. When the magnet armature 11 hits the first stop 14, it lifts the valve needle 8 out of the valve seat 21. The closure body 20 releases the injection opening 16 for injecting the medium, in particular of the fuel, into the combustion chamber.

FIG. 2 shows a diagram for all embodiments of the injection valve 1. On the horizontal axis, the time t is plotted. Shown is from top to bottom, a current waveform 26 to the solenoid 4, a Ventilnadelhubverlauf 27 of the valve needle 8, a Magnetankerhubverlauf 28 of the magnet armature 11, a first pressure curve 29, a second pressure curve 30 and a third pressure profile 31. The first pressure profile 29 is at a the side facing away from the outlet of the armature 11 is measured. Accordingly, this pressure increases when opening the injection valve 1. The second pressure curve 30 is measured below the stop sleeve 13. Here, the pressure remains relatively constant during opening. The third pressure curve 31 is measured in the cavity 19. This pressure curve falls accordingly when tightening the armature 11 by the Pole 5 from. About the negative pressure according to the third pressure curve 31, the valve needle 8 is tightened in the opening direction of the armature 11. If the magnetic coil 4 is traversed by a current, the armature 11 starts its movement until it hits the first stop 14 after overcome Ankerfreweg and lifts the valve needle 8 from the valve seat 21. By moving the magnet armature 11, the drawn pressure curves.

FIG. 3 shows the injection valve 1 according to a second example, which does not belong to the claimed subject matter. Identical or functionally identical components are provided with the same reference numerals in all embodiments and examples. In the second example, the second spring 25 is no longer disposed between the armature 11 and the inner pole 5. Here is a spring cup 32 is provided. This spring cup 32 is firmly connected to the armature 11 and engages behind or engages under the stop sleeve 13 on a side facing the outlet. Between the spring cup 32 and the stop sleeve 13, the second spring 25 is arranged. The upper guide 32 is executed directly between the valve needle 8, in particular the stop ring 12, and the inner pole 5.

FIG. 4 shows the injection valve 1 according to a third example, which does not belong to the claimed subject matter. The same or functionally identical components are provided in all and examples with the same reference numerals. The third example corresponds to the second example except for the formation of the cavity 19. The magnet armature 11 facing side of the second stop 15 is stepped in the third example. To form this gradation, a shoulder 33 extending in the direction of the armature 11 is provided on the stop sleeve 13. Between this shoulder 33 and the base body 9 of the valve needle 8, the cavity 19 is formed.

FIG. 5 shows the injection valve 1 according to a fourth a fourth example, which does not belong to the claimed subject matter. The same or functionally identical components are provided in all and examples with the same reference numerals. In contrast to the third For example, in the fourth example, the shoulder 33 extends much further toward the magnet armature 11, increasing the volume of the cavity 19. Preferably, the shoulder 33 is here substantially narrower than in the third example, whereby the hydraulic adhesive forces between paragraph 33 and armature 11 reduced become. The armature 11 can thereby be moved faster on the valve needle 8.

FIG. 6 shows the injection valve 1 according to an embodiment of the invention. Identical or functionally identical components are provided with the same reference numerals in all embodiments and examples. In the exemplary embodiment, the armature 11 is formed so that it at least partially immersed in the cavity 19. The shoulder 33 engages laterally around the armature 11, so that a gap 34 is formed.

In the fourth example, the size of the gap 34 is dependent on the distance between stop sleeve 13 and armature 11. In the present embodiment, the width of the gap 34 over a certain distance regardless of the distance between armature 11 and stop sleeve 13. This results in the fourth example a path-dependent throttle via the gap 34. In the present embodiment, this throttle is largely away from the gap 34.

In prior arrangements, the second stop 15 was flat on the armature 11 at. This plane-parallel nip can cause the two components to stick together hydraulically to such an extent that the injection valve is greatly delayed or does not open at all. As shown in the first two examples, the magnet armature 11 facing side of the stop sleeve 13 is wedge-shaped or inclined, so that this hydraulic bonding can not occur. Alternatively, the second stop 15 facing side of the armature 11 may be formed inclined relative to the longitudinal axis 7. Furthermore, alternatively, both opposing surfaces may be inclined or wedge-shaped. The third example shows a variant in which this hydraulic bonding is prevented by at least one simple gradation. The gradation can be formed on the stop sleeve 13 or else on the magnet armature 11, as shown in the figures.

The omission of the spring cup 32 in the first example leads to a cost reduction for the individual production and assembly and reduces the decisive for the noise moving mass. Due to the omission of the Spring cup 32 in the first example, especially the surface of the second stop 15 and thus the hydraulic force can be increased to open the valve, since no more space for the assembly of the spring cup 32 must be kept. Thus, in all the examples presented here instead of the spring cup 32, the arrangement of the second spring 25 as shown in the first example can be selected.

According to the invention presented here, the armature 11 and the stop sleeve 13 are no longer hydraulically connected to each other only by a small plane-parallel nip, as was the case in the prior art. Between the magnet armature 11 and the stop sleeve 13 according to the invention exists with the medium-filled cavity 19. A pressure equalization between the cavity 19 and the environment can on the one hand on the guide gap between armature 11 and valve needle 8 and the other by the gap 34 between the stop sleeve 13 and armature 11 will take place. In particular, in the present embodiment, the speed of the pressure compensation via the throttle point, formed by the gap 34, between armature 11 and stop sleeve 13 are set, which is independent of the relative position of the armature 11 to the stop sleeve 13 in the embodiment. In all exemplary embodiments and examples, the magnet armature 11 moves so fast that the volume between magnet armature 11 and stop sleeve 13 increases, the third pressure profile 31 drops. This creates a valve needle 8 opening force. This force is equal to the pressure difference between the second pressure curve 30 and the third pressure curve 31 multiplied by the area of the second stopper 15. Particularly advantageously, the volume and the throttle between armature 11 and stop sleeve 13 are designed when the largest hydraulic force in the Moment acts when the armature 11 meets the stop ring 12. When closing the valve in all the embodiments and examples described here, the positive effect that the movement of the magnet armature 11 is damped after the valve needle 8 has pressed the closure body 20 into the valve seat 21. The magnet armature 11 continues its movement after the needle closure and is damped by the hydraulic forces that arise between the magnet armature 11 and the stop sleeve 13. In the fourth example, the throttle through the gap 34 through the relative position of the armature 11 and stop sleeve 13 dependent. As a result, lower opening forces are to be expected for large anchor free paths than in the embodiment according to the embodiment. When needle closing, however, a greater damping of the magnetic armature movement is achieved by the embodiment in the fourth example, since the throttling action increases, the closer the armature 11 of the stop sleeve 13 comes.

Claims (4)

1. Injection valve (1) for injecting a medium, in particular for injecting fuel, into a combustion chamber, comprising:

   - a housing (2) with at least one spray opening (16) on an outlet side (17),

   - a magnet coil (4),

   - a magnet armature (11) which can be moved linearly by means of the magnet coil (4),

   - a linearly movable valve needle (8) for opening and closing the spray opening (16) with a first stop (14) on an outlet-averted side of the magnet armature (11) and a second stop (15) on an outlet-facing side of the magnet armature (11),

   - wherein the magnet armature (11) is linearly movable, between the first stop (14) and the second stop (15), relative to the valve needle (8), and

   - wherein, for the second stop (15), a first stop surface and a second stop surface situated opposite the first stop surface are formed, wherein, on the first stop surface, there is arranged a hydraulic cushion formed as a cavity (19) filled with the medium, and wherein the cavity (19) is open on the side facing towards the second stop surface, characterized in that a first surface, which is parallel to the longitudinal axis (7) of the valve needle (8), is provided on the magnet armature (11) and a second surface, which is parallel to the longitudinal axis (7) of the valve needle (8), is provided on the second stop (15), wherein, between the first surface and the second surface, there is formed a gap (34) for the throttled supply and discharge of the medium from the cavity (19), and

   in that a spring pot (32) is provided which is fixedly connected to the magnet armature (11), and
   in that a second spring (25) is provided which acts on the magnet armature (11) in the direction of the outlet, wherein the second spring (25) is supported with one end on the spring pot (32) and with the other end on the valve needle (8), and in that, as a connection between the axial gap (34) and the interior of the spring pot (32), a radial gap between magnet armature (11) and second stop (15) is formed as the open side.
2. Injection valve according to Claim 1, characterized in that the first stop surface with the cavity (19) are formed on the valve needle (8) over the full circumference.
3. Injection valve according to one of the preceding claims, characterized in that the second stop surface is formed so as to protrude partially into the cavity (19) during a movement of the valve needle (8) and/or of the magnet armature (11).
4. Injection valve according to one of the preceding claims, characterized by a first spring (24) which forces the valve needle (8) in the direction of the outlet.

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