Patent Application
20150247479
1. Field of the Invention
The present invention relates to an injection valve for injecting a medium, e.g., for injecting fuel into a combustion chamber, which injection process may be developed as a port injection or as a direct injection.
2. Description of the Related Art
The related art includes known injection valves for the injection of Otto fuel. They have a valve needle which is moved against a closing spring by an actuator, e.g., an electromagnet or a piezo actuator, in such a way that a desired fuel quantity is selectively introduced directly into the combustion chamber. In the case at hand, an injection valve is examined in which the magnetic armature is decoupled from the valve needle. When the injection valve is opened, the magnetic armature is meant to rapidly detach from the lower stop (second stop) on the valve needle, to rapidly overcome the armature free travel, and to quickly open the valve when striking the upper (first) stop. If the energization of the valve is stopped, then the valve needle closes again. Once the valve needle seals the valve seat again, the magnetic armature continues its movement until it strikes the lower stop. The armature bounces off the lower stop multiple times before reattaining its idle position. The time until the magnet armature is reset to the idle position again is decisive for the ability of the valve to deliver injections in rapid succession and with high accuracy. A squish gap is usually developed at the lower stop, i.e., between the magnetic armature and the corresponding stop sleeve on the valve needle. The medium to be injected is squeezed into this squish gap, so that the magnetic armature is reset to the idle position in a damped and rapid manner during the closing. However, by damping the movement during the opening, the squish gap prevents a rapid opening. As a compromise, the squish gap must therefore be configured in such a way that the magnet armature opens the valve with sufficient speed and is reset to its idle position with sufficient speed as well.
The injection valve of the present invention allows for better damping of the magnet armature and thus makes it possible to reset the magnet armature to its idle position more rapidly than previously possible after the injection valve is closed. At the same time, the damping during the opening of the injection valve is reduced in the present invention, so that the injection valve opens more rapidly. More specifically, the following advantages thus result in the opening of the injection valve: The magnet armature detaches from the valve needle more rapidly than previously, which increases the dynamic response of the valve and therefore improves the function. The required opening force is reduced, so that the current consumption of the injection valve, and thus the entire energy requirement of the vehicle, is lower. This lowers the consumption of the vehicle. The following advantages result in the closing of the injection valve: The movement of the magnet armature is damped to a greater extent than before. The magnet armature therefore reaches its idle position earlier than previously, so that injections are able to be delivered in rapid succession and with high repeat accuracy. The injection valve according to the present invention provides new injection strategies that make possible a combustion featuring lower pollutant emissions and lower consumption. The better damping in the closing of the injection valve reduces the noise that is created by the pulse transmission of the magnet armature to the valve needle. All of these advantages are achieved by an injection valve according to the present invention, which includes a housing having at least one spray-discharge orifice on a discharge side, a solenoid coil and a magnetic armature, which is linearly movable with the aid of the solenoid coil. In addition, the injection valve has a valve needle. This valve needle is used for the opening and closing of the at least one spray-discharge orifice. The valve needle extends along a longitudinal axis and is linearly movable. A through hole is developed in the magnet armature, in which the valve needle is situated. The magnet armature is linearly movable between a first and a second stop in relation to the valve needle. This creates a two-mass system. The first stop is formed on a side of the magnet armature facing away from the discharge. For example, the first stop is formed by a ring on the valve needle. The second stop is formed on a side of the magnet armature facing the discharge. According to the present invention, the second stop is formed by a stop element and a counter element. The stop element and the counter element strike each other at the second stop. The stop element has a stop face for this purpose. A counter face situated across from the stop face is developed on the counter element. The stop face and counter face strike each other at the second stop. The stop element has an elastic design, so that an angle between the longitudinal axis and stop face changes when the counter face and the stop face strike each other. In particular, the stop face is inclined toward the counter element prior to and following the contact between stop element and counter element. As soon as the counter element and stop element make contact with each other, the stop element is elastically deformed, so that the space between the stop face and counter face becomes smaller. Because of the elastic development of the stop element according to the present invention, it is possible that there is a change in the squish gap and the throttle flow between the stop face and counter face when the stop face and counter face move towards and away from each other. This enables a very precise adjustment of the damping in the opening and closing of the injection valve.
The stop element is preferably permanently connected to the valve needle. The counter element will then be situated on the magnet armature. The counter element in particular is an integral component of the magnet armature. In the most straight-forward case, the counter face is the side of the magnet armature that faces the stop face. In an alternative development, it is possible that the stop element is permanently connected to the magnet armature. The counter element will then be permanently joined to the valve needle. Decisive is that at least one of the opposing surfaces on the second stop has an elastic design. This at least one elastic surface is referred to as stop face within the scope of the present application.
The stop element or counter element is preferably integrated into the valve needle. As an alternative, the stop element or counter element is integrated into the magnet armature.
It is furthermore preferably provided that the angle between the longitudinal axis and stop face without contact between stop face and counter face is less than 90° at least regionally. The angle is defined on the side of the stop face that faces the counter face. This means that the angle of less than 90° defines that the stop face is inclined toward the counter face. It suffices if the stop face has this inclination at the corresponding angle only in certain places. When the counter face strikes the stop face, the stop face will be deformed, so that the angle becomes greater.
When lifting off from the stop face and counter face, i.e., during the opening of the injection valve, the stop element relaxes again, so that the angle becomes smaller again. Because of the development of the angle it is possible that the movement of the magnet armature is damped only by a throttle flow but no squish gap when the injection valve opens. As soon as the counter face and the stop face move slightly apart from each other, the stop element relaxes and the stop face thus inclines in the direction of the counter face. As a result, the stop face and counter face are no longer aligned in parallel with one another, and no squish gap is present. Only a throttle flow, i.e., the flow of the medium to be injected, which flows out of the region between stop face and counter face, dampens the opening movement of the magnet armature.
When the injection valve closes, the stop face and the counter face move toward each other. In so doing, the stop face is initially inclined in the direction of the counter face, so that a relatively large space filled with the medium is present between the stop face and counter face. The movement is initially dampened by a throttle flow, and as soon as the stop face and counter face make contact with each other, the stop face is deformed, so that the stop face aligns itself parallel to the counter face. This creates a squish gap for damping the movement of the magnet armature. The damping effect therefore increases as the clearance between stop face and counter face becomes smaller.
It is provided, in particular, that the angle without the contact between stop face and counter face amounts to maximally 89.99 degrees, preferably maximally 89.85 degrees. As already described earlier, this angle need not be provided across the entire stop face.
It is furthermore preferably provided that as a result of the striking contact between counter face and stop face, the angle is elastically deformed by at least 0.01 degrees, preferably at least by 0.15 degrees. In an especially preferred specific embodiment, the stop face is deformed until the stop face and counter face are in parallel alignment with each other.
It is furthermore advantageous that the stop face is subdivided into an inner section and an outer section. The inner section is closer to the longitudinal axis than the outer section. Especially preferably, the stop face is an annular surface around the valve needle. The inner section is an inner annular surface. The outer section is a further annular surface lying outside of the inner section. The angle without contact between stop face and counter face is larger at the outer section than at the inner section. In this context it is preferably provided that the stop face inclines more heavily in the direction of the counter face as the distance from the longitudinal axis increases.
Especially preferably, it is provided that the inner section without contact between stop face and counter face is developed parallel to the counter face. As an alternative, the inner section may be slightly inclined in the direction of the counter face or have a concave design.
On the stop element, a side facing away from the counter face is referred to as outer surface. This outer surface should also be formed appropriately, so that enough elasticity is available for the deformation of the stop face. As a consequence, the outer surface is preferably formed so that it inclines in the direction of the counter element or is at least regionally concave. As an alternative, the outer surface may regionally also lie parallel to the stop face. It is also decisive in this context that the stop element is as thin as possible, so that the stop face is able to deform elastically.
In order to ensure the elastic deformability of the stop element, and thus also of the stop face, grooves are preferably provided in the stop element. These grooves are especially preferably formed over the entire circumference of the longitudinal axis.
The first stop is preferably formed by a step or by a ring on the valve needle.
Exemplary embodiments of the present invention are described in detail below with reference to the accompanying drawing.
In the following text, a first exemplary embodiment of injection valve 1 will be discussed with the aid of
In addition, a magnet armature 8, which is connected to a spring cup 9, is situated inside housing 2. On a side of magnet armature 8 that faces away from the discharge is a ring 10, which is fixedly secured on valve needle 6. This ring 10 forms a first stop for magnet armature 8. On a side of magnet armature 8 facing the discharge is a stop element 12. This stop element 12 forms a second stop together with magnet armature 5.
Both valve needle 6 and magnet armature 8 are linearly movable along longitudinal axis 15. The movement of magnet armature 8 is delimited by the first and second stop.
A plurality of channels 16 for the medium to be injected are developed in magnet armature 8. In addition or as an alternative, valve needle 6 may also have a hollow design.
Valve needle 6 is loaded in the direction of discharge side 3 by means of a first spring 11. A second spring 13 between spring cup 9 and stop element 12 loads magnet armature 8, likewise in the direction of discharge side 3.
Magnet armature 8 is moved by energizing solenoid coil 5. By way of the first and second stop, magnet armature 8 carries valve needle 6 along. The distance between the two stops defines an armature free travel 14.
A surface on stop element 12 facing counter element 18 is referred to as stop face 17. Situated across from stop face 17 is a counter face 19 on counter element 18. A side on stop element 12 facing away from counter element 18 is referred to as outer surface 21. The plotted angle α is defined between stop face 17 and longitudinal axis 15. Angle α is measured on the side of stop face 17 facing counter element 18.
Stop element 12, and thus also stop face 17, are elastically deformable. When counter element 18, i.e., magnet armature 8, strikes stop element 12, stop element 12 is elastically deformed, so that angle α becomes larger.
A first height 25 extends parallel to longitudinal axis 15, from the upper end of through hole 28 to the outer end of stop face 17. The outer end of stop face 17 is referred to as peak 27. A second height 26 designates the extension of stop element 12 parallel to longitudinal axis 15. The elasticity of stop face 17 in the illustrated exemplary embodiment is achieved in that the two heights 25, 26 are greater than 0.
In the following figures, reference numeral 29 denotes a throttle flow of the medium to be injected. The dashed illustration of stop element 12 shows the elastic deformation.
Because of the applied magnetic field at solenoid coil 5, magnet armature 8 is pulled in the direction of the inner pole in
Outer surface 21 is situated partially in parallel with counter face 19 and partially inclines toward counter face 19. More specifically, outer surface 21 is inclined in the direction of the counter face roughly in the region of outer section 24, so that sufficient elasticity of stop element 12 is provided there.
The various exemplary embodiments show possible geometries of stop element 12. In the exemplary embodiments, stop faces 17 are usually in the form of a wedge, since the wedge form is easy to measure and produce. The exemplary embodiments may naturally also be combined. For example, grooves 22 shown in
All exemplary embodiments shown illustrate stop face 17 and counter element 19 in a form in which it is fixedly joined to valve needle 6. Accordingly, magnet armature 6 in the exemplary embodiments is defined as counter element 18 having counter face 19. In the same way, it is possible to develop an elastic stop element 12 which is permanently connected to magnet armature 6. Correspondingly, counter element 18 would then be fixedly joined to valve needle 6. In the simplest development, counter face 19 is a planar rigid surface. It is also possible for counter face 19 to have a certain inclination and elasticity.
| Number | Date | Country | Kind |
|---|---|---|---|
| 102012217322.6 | Sep 2012 | DE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2013/065812 | 7/26/2013 | WO | 00 |
