Injection valve with a needle biased by a spring

Description

[0001] The invention describes an injection valve according to the preamble of claim 1.
Modern injection valves have a very dynamic closing and opening function. This is necessary for attaining a precise starting point of the injection and a precise ending point of the injection. However, the fast opening and closing function results in a high speed of the closing member that pushes against a valve seat for closing the valve. To reduce the speed of the needle high forces are necessary which are induced in the valve seat and in the sealing faces of the needle. The high forces cause a relatively high abrasion on the sealing face and on the valve seat.

[0002] To reduce the bouncing effect, the state of art proposes an anti-bounce disc, which reduces the needle speed when approaching the valve seat. The anti-bounce disc, however, has the disadvantage that it is within the hydraulic flow path of the injected fuel and causes a hydraulic resistance to the fuel.

[0003] On the other hand it is also known to use a valve seat made of an elastomere to attain a soft impact of the needle on the valve seat.

[0004] DE 100 65 528 A1 describes an injection valve with a hollow needle and an armature that is arranged at the upper part of the needle and held in place by a pin. The pin allows the needle to move a short distance inside the armature in axial direction thus providing a pre-lift gap. A spring that is fixed to the upper end of and arranged inside the needle pushes against the pin and thus keeps the pre-lift gap open in the closed valve state.

[0005] US 5 088 467 A discloses an injection valve comprising an armature with a guide tube. Inside the guide tube a spring is arranged. At the lower end of the guide tube a needle is movably arranged in the guide tube. The needle is pushed in the direction of the valve seat by the spring.

[0006] It is a task of the present invention to provide an injection valve with a needle and a valve seat, in which the bouncing of the needle on the valve seat is dampened, and in which the needle is precisely guided in its axial movement.

[0007] The task of the invention is attained by an injection valve according to claim 1. One advantage of the inventive injection valve is that the needle can be slided in a holding element and between the holding element and the needle a damping spring is arranged. The needle slides against the tension of the damping spring when the needle is pushed onto the valve seat. Therefore the force with which the needle is pushed onto the valve seat is reduced because only the mass of the needle is pushed onto the valve seat and not the mass of the holding element. Furthermore the tension of the damping spring afterwards holds the needle on the valve seat in a closed position. The needle does not lift off the valve seat in the closed position.

[0008] The holding element is shaped as a sleeve and the needle is guided within the sleeve. The spring is arranged between a wall of the sleeve and the needle, biasing the needle in direction of the valve seat. The shape of the sleeve has the advantage that the needle can be guided precisely along a longitudinal axis of the injection valve and it is enough space for providing a relatively strong spring.

[0009] The sleeve is realized as a stepped sleeve with two different diameters. The needle is guided in the region with the smaller diameter. In the region with the greater diameter a rim of the needle is arranged. The rim of the needle has a greater diameter than the smaller diameter of the sleeve and the spring is arranged between the rim of the needle and an opposite side wall of the sleeve.

Brief description of the drawings.

[0010] 

Fig. 1 depicts a longitudinal sectional view of an injector according to an embodiment of the present invention, and

Fig. 2 depicts a detailed view of the needle assembly.

[0011] Before one embodiment of the inventions is explained in detail, it is to be understood that the invention is not limited in this application to the details of construction and the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or being carried out in various ways.

[0012] A preferred embodiment of a fuel injector according to the present invention will now be described with reference to the drawings. Fig. 1 shows a longitudinal view of a fuel injector 1 used in a motor vehicle engine. The fuel injector is basically symmetrical to a central symmetry axis.

[0013] The injection valve 1 includes a valve body 2. Inside the valve body 2, an orifice plate 3 is arranged adjacent to a lower end of the valve body 2. The orifice plate 3 includes an orifice 4 in a central position. The orifice in the orifice plate 3 provides fluid communication between the fuel injector 1 and a combustion chamber of a motor vehicle engine. In the orifice plate 3 a metallic valve seat 5 is provided. At an inner side of the orifice plate 3, the valve seat 5 surrounds the orifice 4, the purpose of which will be described below.

[0014] The valve body 2 also houses a needle assembly. The needle assembly comprises an armature 7 that is connected by a needle 6 with a closing member 8. The closing member 8 is a tip of the needle 6 that is dedicated to the valve seat 5. The armature 7 can be moved within the valve body 2 along a longitudinal axis of the fuel injector 1. Depending on the position of the armature 7, the closing member 8 is in a closed position biased against the valve seat 5, closing the orifice 4 preventing a fuel injection. In an opening position, the needle 6 is lift off the valve seat 5.

[0015] The armature 7 is shaped as a sleeve with an upper end ring face 9 and a central bore 10. The closing member 8 is appropriately sized to be received in the valve seat 5. In conjunction, the needle 6 and the valve seat 5 operate as a fuel valve that selectively opens and closes the injected valve 1.

[0016] The valve body 2 houses an inlet tube 18. The inlet tube 18 is typically made from metal and includes a lower end ring face 13. The end ring face 13 is adjacent to the upper end ring face 9 of the armature 7. The inlet tube 18 also includes a bore that houses an adjustment sleeve 14 and a portion of a spring 15. The spring 15 is constrained between the lower end of the adjustment sleeve 14 and a seat inside the bore 10 of the armature 7. The adjustment sleeve 14 is adjustably fixed relative to the inlet tube 18 and biases the spring 15 against the seat in the armature bore 10, thereby biasing the needle 6 into a first position, wherein the closing member 8 rests in the valve seat 5 and blocks fluid communication between the fuel injector 1 and the combustion chamber. While in the closed position, the upper end ring face 9 of the armature 7 is arranged at a distance from the lower end ring face 13 of the inlet tube 18 creating a gap of approximately 20 microns between the armature 7 and the inlet tube 18.

[0017] The injection valve 1 further includes an electromagnetic coil assembly 16 that encircles a portion of the inlet tube 18 and is housed within a metallic housing 17. The electromagnetic coil assembly 16 can be selectively charged to create a magnetic field that attracts the armature 7 towards the lower end ring face 13 of the inlet tube 18 into a second position. The biasing force of the spring 15 is overcome in such a way that the closing member 8 is raised from the valve seat 5, allowing fuel to flow through the orifice of the orifice plate 3 into the combustion chamber. While in the open position, the upper end ring face 9 of the armature 7 contacts the lower end ring face 13 of the inlet tube 18. The needle 6 remains in the open position until the charge is removed from the electromagnetic coil assembly 16 at which point the spring 15 biases the valve member 6 back into the first position.

[0018] At an upper end of the inlet tube 18 a fuel filter 19 is arranged. A fuel passage way 20 leads through the fuel filter 19, the bore of the adjustment sleeve 14, the inlet tube 18, the bore of the armature 7 and holes 11 of the holding element to an injection chamber 28 that is arranged between the valve body 2 and the needle 6.

[0019] The electromagnetic coil assembly 16 is selectively charged via an external power lead that applies electricity to the electromagnetic coil assembly 16. The power lead is connected to the coil assembly 16 via a connector terminal 21 that is mounted on an outer surface of the inlet tube 18 via a clip portion. The connector terminal 21 is electrically connected, via soldering or any other suitable method, to terminals of the coil assembly 16.

[0020] The fuel injector 1 also includes a second housing 22 that surrounds portions with the inlet tube 18, clip connector 21, metallic housing 17 and valve body 2. The second housing 22 is preferably plastic and is preferably molded over the injection valve 1.

[0021] Figure 2 depicts in greater detail a sectional view of the lower part of the fuel injection valve of Figure 1. The spring 15 is biased against a rim 35 that is arranged at the lower end of the sleeve part of the armature 7. A second sleeve 32 is fixed to the sleeve part of the armature 7. The second sleeve 32 extends into a third sleeve 33. The diameter of the second sleeve 32 is larger than the diameter of the third sleeve 33. The needle 6 is guided by the third sleeve 33 and extends in the second sleeve 32 with a plate 34. The plate 34 has the shape of a circular plate, the diameter of which is larger than the diameter of the third sleeve 33 and smaller than the diameter of the second sleeve 32. Between the plate 34 and the rim 35 of the armature 7 a second spring 36 is arranged. The second spring 36 biases the needle 6 towards the valve seat 5. Between the needle 6 and the valve body 2 a fuel chamber 28 is arranged that is connected with the fuel passage way. The second sleeve 32 comprises the holes 11 and provides a fluid connection between the fuel chamber 28 and the inlet tube 18. The bore 10 of the armature 7 is connected with the inner region second sleeve 32, in which the second spring 36 is arranged.

[0022] During the injector standard operation, the armature 7 is pulled towards the lower end ring face 13 of the support tube 12. If the injection is completed, the coil assembly 16 is deenergized and the armature 7 is biased down in direction of the valve seat 5 by the spring 15 to close the orifice 4. The needle 6 is also moved to the valve seat 5. At the end of the closing travel, the needle 6 contacts the valve seat 5 with its sealing face. The contact between the needle 6 and the valve seat 6 generates a bouncing effect that the invention intends to eliminate. The invention provides a non-rigid link between the armature 7 and the needle 6. The link is established by a slideable guiding connection between the armature 7 and the needle 6 and the second spring 36 that is arranged between the armature 7 and the needle 6. When the needle is pushed onto the valve seat 5 by closing the injection valve, the needle 6 is moved upwards relative to the armature 1 against the tension of the second spring 36. In this way the impulse of the armature 7 and the second and third sleeve 32, 33 is not transferred to the valve seat 5. Therefore the impulse by means of which the needle 6 is pushed onto the valve seat 5 is reduced. The tension of the second spring 36 holds the needle 6 in the closed position after pushing the needle 6 onto the valve seat by the armature 7.

Claims

1. Injection valve (1) comprising

- a housing (2),

- a fuel chamber (28) with an inlet to the fuel chamber,

- an orifice (4) with a valve seat (5),

- a holding element (7, 32, 33) that is movably arranged within the housing (2), whereby the holding element (7, 32, 33) is connected with a needle (6), whereby a tip of the needle (6) is arranged within the fuel chamber and comprises a sealing face that is assigned to the valve seat (5), the holding element (7, 32, 33) comprises a sleeve (33) and the needle (6) is guided within the sleeve (33),

- an actuator that controls the position of the holding element (7, 32, 33),

- a spring (15) that is arranged between the housing (2) and the holding element (7, 32, 33) that biases the holding element (7, 32, 33) and the needle (6) to the valve seat (5),

- a second spring (36) that is arranged between an end face of the needle (6) and a holding face of the holding element (7, 32), that the needle (6) is movably guided in a moving direction of the needle (6) in the holding element (7, 32, 33), and that the needle (6) is biased towards the valve seat (5) by the second spring (36),

characterised in that the sleeve comprises a first and a second section (32, 33) that a first section (32) has a larger diameter than a second section (33), that at one end of the first section the holding face is arranged, that the other end of the first section (32) changes to the second section (33), that the second section (33) is a guiding for the needle (6), and that the end of the needle (6) which is arranged in the first section (32) comprises a plate with a larger diameter than the second section.

Ansprüche

1. Einspritzventil (1), umfassend:

ein Gehäuse (2),

eine Kraftstoffkammer (28) mit einem Einlass zu der Kraftstoffkammer,

eine Öffnung (4) mit einem Ventilsitz (5),

ein bewegbar innerhalb des Gehäuses (2) angeordnetes Halteelement (7, 32, 33), wodurch das Halteelement (7, 32, 33) mit einer Nadel (6) verbunden ist, wodurch eine Spitze der Nadel (6) innerhalb der Kraftstoffkammer angeordnet ist und eine Dichtfläche umfasst, die dem Ventilsitz (5) zugeordnet ist, während das Halteelement (7, 32, 33) eine Hülse (33) umfasst und die Nadel (6) innerhalb der Hülse (33) geführt ist,

ein Stellglied, das die Position des Halteelements (7, 32, 33) steuert,

eine zwischen dem Gehäuse (2) und dem Halteelement (7, 32, 33) angeordnete Feder (15), die das Halteelement (7, 32, 33) und die Nadel (6) gegen den Ventilsitz (5) vorspannt,

eine zweite Feder (36), die zwischen einer Endfläche der Nadel (6) und einer Haltefläche des Halteelements (7, 32, 33) angeordnet ist, während die Nadel (6) bewegbar in einer Bewegungsrichtung der Nadel (6) in dem Halteelement (7, 32, 33) geführt und in Richtung des Ventilssitzes (5) durch die zweite Feder (36) vorgespannt ist,

dadurch gekennzeichnet, dass die Hülse einen ersten und einen zweiten Abschnitt (32, 33) aufweist, wobei ein erster Abschnitt (32) einen größeren Durchmesser als ein zweiter Abschnitt (33) aufweist, während an einem Ende des ersten Abschnitts die Haltefläche angeordnet ist, wobei das andere Ende des ersten Abschnitts (32) sich mit dem zweiten Abschnitt (33) verändert, während der zweite Abschnitt (33) eine Führung für die Nadel (6) darstellt, wobei das in dem ersten Abschnitt (32) angeordnete Ende der Nadel (6) eine Platte mit einem Durchmesser umfasst, der größer ist als der zweite Abschnitt.

Revendications

1. Soupape d'injection (1) comprenant

- un boîtier (2)

- une chambre de carburant (28) munie d'une entrée donnant dans la chambre de carburant,

- un orifice (4) muni d'un siège de soupape (5),

- un élément de retenue (7, 32, 33) qui est disposé mobile dans le boîtier (2), de telle sorte que l'élément de retenue (7, 32, 33) est relié à une aiguille (6), de sorte qu'une pointe de l'aiguille (6) est disposée dans la chambre de carburant et comprend une face d'étanchéité qui est prévue pour le siège de soupape (5), l'élément de retenue (7, 32, 33) comprend un manchon (33) et l'aiguille (6) est guidée dans le manchon (33),

- un actionneur qui commande la position de l'élément de retenue (7, 32, 33),

- un ressort (15) qui est disposé entre le boîtier (2) et l'élément de retenue (7, 32, 33) et qui sollicite l'élément de retenue (7, 32, 33) et l'aiguille (6) en direction du siège de soupape (5).

- un second ressort (36) qui est disposé entre une face d'extrémité de l'aiguille (6) et une face de retenue de l'élément de retenue (7, 32), que l'aiguille (6) est guidée mobile dans une direction de mouvement de l'aiguille (6) dans l'élément de retenue (7, 32, 33) et que l'aiguille (6) est sollicitée en direction du siège de soupape (5) par le second ressort (36).

caractérisée en ce que le manchon comprend une première section et une seconde section (32, 33), qu'une première section (32) a un plus grand diamètre qu'une deuxième section (33), qu'à une extrémité de la première section est disposée la face de retenue, que l'autre extrémité de la première section (32) se transforme en la seconde section (33), que la seconde section (33) est un guidage pour l'aiguille (6) et que l'extrémité de l'aiguille (6) qui est disposée dans la première section (32) comprend une plaque ayant un plus grand diamètre que la seconde section.

Drawing