EP2025922B1 - Fuel injector valve for combustion engines - Google Patents

Description

The invention relates to a fuel injection valve for internal combustion engines, in particular a solenoid valve for common rail injectors (CRI), according to the preamble of claim 1.

State of the art

From the European patent application EP 1 612 403 A1 Injectors for high-speed, self-igniting internal combustion engines are known which inject the fuel directly into a combustion chamber of an internal combustion engine.

In solenoid valves for common rail injectors according to the prior art, the design always results in an influence of the rail pressure on the stroke of the switching valve or the control valve (armature stroke). The reason for this lies in elastic deformations which influence the armature stroke and which are directly or indirectly subject to rail pressure.

In certain types of solenoid valves, the influence on the armature stroke is particularly large. These include those solenoid valves in which the upper stroke stop is formed on the magnet. Due to the rail pressure, the situation occurs that the valve seat changes its axial position relative to the holding body, whereas the position of the upper stroke stop remains unchanged. Overall, this means that the armature stroke decreases with increasing rail pressure.

The prerequisite for the reliable operation of the solenoid valve is that the armature stroke is above a minimum value at all rail pressures, so that even at the highest rail pressure the armature stroke still achieves the minimum value. In the depressurized state, therefore, an armature stroke must be set which is significantly above the minimum value.

However, a large armature stroke causes the armature or the actuating element is accelerated over a longer distance upon actuation of the electromagnet and thus builds up a greater kinetic energy. (The same effect also occurs when the valve spring pushes the actuator back to the seal seat).

When striking the control element on the upper stroke stop (or the valve seat) therefore a shock takes place, which leads to a considerable load on the control element and usually also to a bouncing of the control element. Since the bouncing but has a negative impact on the metering accuracy of the injector, a large anchor stroke is undesirable.

It should be noted that the aforementioned problems can also occur in valves with a piezoelectric actuator. Therefore, findings that are found in this context for a solenoid valve, also directly opportunities to improve a valve with piezoelectric actuator.

Disclosure of the invention

The object of the invention is to show a fuel injection valve, in particular a solenoid valve, in which the armature stroke little changes even at high rail pressure and in particular remains substantially unchanged.

The object is achieved in a fuel injection valve according to the preamble of claim 1, characterized in that between the actuator and the guide element, a preferably rigid intermediate element is arranged so that a mechanical hold-down force acting on the actuator is introduced via the intermediate element in the guide element, or conversely, when the guide element exerts a force under the influence of the rail pressure, this force acts on the actuator via the intermediate element. One advantage is that, when setting the armature stroke, no reduction in the armature lift at high rail pressures has to be taken into account. The fuel injection valve, which is also referred to as an injector, can therefore be operated in the entire pressure range with a small armature stroke, resulting in, inter alia, advantages in terms of the bounce and the energy consumption of the valve.

The proposed improvement can be applied to both a valve with an electromagnetic actuator (solenoid valve) and a valve with a piezoelectric actuator (piezo valve), so that both solenoid valves and piezo valves benefit from the disclosure of the invention. For the sake of simplicity, however, the invention will be explained only by the example of a solenoid valve.

One aspect of the invention is the fact that it is now possible to apply a force to the guide element or the guide pin of the valve in order to counteract an extension of the guide element by the rail pressure. Since the intermediate element is essentially rigid, that is to say that, unlike a resilient element or a spring, only very slight elastic or plastic deformations are possible, large mechanical forces can also be applied by the actuator or the electromagnet to the guide element.

The application of the force to the guide element is made possible in particular by electromagnet and guide element on the same fixed reference element, preferably on the holding body of the valve, supported. If a force is now exerted on the electromagnet, for example by means of a screw element which presses the electromagnet from the reference element in the direction of the guide element, this force also acts on the guide element. Since the guide member is supported against the same rigid reference element, the guide element can not dodge, but absorbs the force. Conversely, the force exerted by the guide element under the effect of the rail pressure is also absorbed by the actuator.

Another aspect of the invention is that a precise adjustment of the armature stroke is made possible. By biasing the actuator of the solenoid valve, so the electromagnet, against the intermediate element, the intermediate element already exerts a pressure against the guide element in the state without rail pressure. As a result, the guide element is subject to a-naturally slight elastic deformation that shortens the length of the guide element. Depending on the size of the mechanical force exerted by the electromagnet on the intermediate element on the guide element, the armature stroke can be accurately adjusted. A complicated setting on exactly classified shims can then be omitted or used only for rough presetting.

The guide element and the intermediate element can be embodied in various configurations, which will be explained later in the application. However, it should already be noted at this point that the intermediate element can also be designed as part of the guide element or integrally with the guide element.

A preferred embodiment of the valve is characterized in that the intermediate element, which is also referred to as an intermediate piece, bears against a narrowed region of a recess in the actuator. This allows an advantageous embodiment of the elements of the valve, since these can be manufactured individually and then put together. The fact that the intermediate piece is supported on the narrowed region of the recess, no further measures (such as a shrinking) are required to ensure the power transmission between the actuator and the intermediate piece.

A further preferred embodiment of the valve is characterized in that the narrowed region is designed as a diameter stage. This embodiment is advantageous in terms of manufacturing technology, since a diameter step, that is to say a region which has a different diameter than another region, can be realized in a simple manner. This is especially true for a solenoid valve, which already has a central bore in the magnetic core, which is then carried out only in a section with a larger or smaller diameter.

A further preferred embodiment of the valve is characterized in that the intermediate element has a head portion which abuts against at least one end face of the constricted portion. On the one hand, this embodiment offers the advantage that the intermediate element can center with its head section in the recess in the actuator. If the diameter of the head portion corresponds to the diameter of the larger diameter portion of the recess, the central axis of the intermediate element can be well defined, in particular with regard to the actuator. Another advantage is that the valve spring can be supported on the head section.

A further preferred embodiment of the valve is characterized in that the head portion has drainage holes. This allows in a simple manner, the fluid connection of the leakage oil chamber with the area above the actuator.

A further preferred embodiment of the valve is characterized in that between the guide element and the intermediate element, a parting line is formed, which is based on a direction from the guide element to the actuator below the sealing seat. For certain design variants, this results in advantages with regard to the arrangement, the design and / or the guidance of intermediate element and / or guide element. The parting line is preferably at the level of the transverse bore in the guide pin.

A further preferred embodiment of the valve is characterized in that the guide element and the intermediate element bear against one another on a respective end face, wherein at least one of the end faces is formed with a drain groove or a part of a drain groove. In this case, the drainage groove in the end face of the guide element and / or the drainage groove in the end face of the intermediate element forms the transverse bore. Due to the hold-down force which is introduced by the actuator through the intermediate element in the guide element, the sealing of the drain groove is also carried out. Since the central bore in the guide element is accessible in this embodiment during parts production from both sides, here is the possibility to arrange an outlet throttle in this central bore and so to reduce the dead volume between drain throttle and sealing seat. It should be noted that the parting line can also be arranged further in the direction of the base of the guide element. In this case, the transverse bore is retained, but then it is part of the intermediate element.

A further preferred embodiment of the valve is characterized in that between the guide element and the intermediate element and / or between the intermediate element and the actuator, a non-magnetic Ankerhubeinstellelement and / or a non-magnetic Restletttspalteinstellscheibe is arranged. In this way, the desired settings can be made easily and reduce or avoid magnetic leakage flux.

A further preferred embodiment of the valve is characterized in that the hold-down force is introduced via an elastic element in the actuator, wherein the elasticity of this element is greater than that of the arrangement of guide element and intermediate element in the region between the sealing seat and support on the actuator. In this embodiment, it is ensured that remaining axial displacements of the sealing seat relative to the holding body by the rail pressure also lead to an axial displacement of the actuator relative to the holding body and are thus compensated. The elastic element can also be designed in one piece with the actuator or the contact element for the actuator in the holding body.

A further preferred embodiment of the valve is characterized in that the actuating element is acted upon by means of a valve spring in the direction of the sealing seat with a force and the valve spring is supported on a head portion of the intermediate element and the adjusting element. In this embodiment results in a compact design.

A further preferred embodiment of the valve is characterized in that central axes of the guide element, the intermediate element and the actuator are aligned with each other. This results in a structurally simple structure, which offers a good symmetrical force distribution.

Further advantages, features and details of the invention will become apparent from the following description in which, with reference to the drawings, various embodiments are described in detail.

Short description of the drawing Show it:

FIG. 1

a longitudinal section through an inventive fuel injection valve with schematically shown supply components;

FIG. 2

an enlargement of FIG. 1 in the area of the control valve;

FIG. 3

an alternative embodiment of a control valve in conjunction with a threaded bandage and

FIG. 4

a control valve with a one-piece embodiment of guide member and control.

Description of the embodiments

In FIG. 1 a fuel injection valve 10 according to the invention with the fuel-supplying components 12 is shown schematically in longitudinal section. The basic mode of operation of such a fuel injection valve 10 is known to the person skilled in the art and will therefore not be explained in detail. More detailed information can be found for example in the cited document and in the application DE 10 2006 027 485 A1 ,

The fuel injection valve 10 has a valve needle 14, a control chamber 16, which is operatively connected to the valve needle 14 is a drain channel 18, which is designed to connect the control chamber 16 with a leakage oil chamber 20, and a control valve 22, which is designed to open and close the drain channel 18.

The control valve 22 has a guide element 24, also called guide pin on which an adjusting element 26, also called sealing sleeve or armature, is held axially displaceable, wherein the actuating element 26 is acted upon in the direction of a sealing seat 28 with a force. The control valve 22 also has an actuator 30, here an electromagnet, which is designed to lift the actuator 26 from the sealing seat 28 up-related to the figure.

In FIG. 2 is an enlargement of FIG. 1 shown in the region of the control valve 22. It can initially be seen that the actuator 30 has a magnetic core 32 with a magnetic coil 34 inserted therein. The actuator 30 has a recess 36, which is formed as a central bore through the magnetic core 32 and has a narrowed portion 38, which is designed here as a diameter stage. At the constricted region 38, an end face 40 is formed, against which a head section 42 of an intermediate element 44 rests.

In the head section 42 drain holes 46 are introduced, which form a fluid passage between the leakage oil chamber 20 and the area above-related to the figure of the head portion 42. At the head portion 42 is a valve spring 48 at one end, while the other end is supported on the actuator 26.

Between the actuator 30 and the actuator 26 is a Restluftspaltsscheibe 50, alternatively or additionally, a Ankerhubeinstellelement. The residual air gap, which prevents magnetic and hydraulic sticking of the armature is necessary at the upper stroke stop, for example, as a complete or partial coating of the end face of the magnetic core 32 and / or the end face of the actuating element 26 or be realized as a ground step in one or both of said end faces.

The intermediate element 44 rests with an end face 52 against an end face 54 of the guide element 24. Between the end faces 52, 54, a parting line 56 is formed, which in this embodiment is above-related to the figure of the sealing seat 28. The drainage channel 18 terminates within the guide element 24 in a transverse bore 58. The central axes 60, 62, 64 of the actuator 30, the intermediate element 44 and the guide element 24 are aligned with each other.

This results overall in a structure in which the rigid intermediate element 44 is supported on one side, the head section 42, on the actuator 30, or here on the magnetic core 32, and on its other side on the end face 54 of the guide element 24. If a hold-down force is now applied to the actuator 30, this force is transmitted to the intermediate element 44 and to the guide element 24. When the rail pressure is applied, the force exerted by the actuator 30 initially counteracts expansion of the guide element 24. If the rail pressure continues to increase, the length of the guide element increases and the sealing seat 28 of the control valve 22 shifts upward. Due to the rigid connection but at the same time the actuator 30 and thus the upper stroke stop perform a very similar or nearly identical movement. Thus, the armature stroke remains independent of the rail pressure. This principle can be used particularly well if the actuator 30, or the magnetic core 32, are not supported at another point. Since the intermediate element 44 to a certain extent the armature stroke on a fixed Value holds, you can also call it Ankerhub fixing.

• bezogen auf die Figur- des Dichtsitzes 28 liegt. Die genannten Stirnflächen bilden hier eine Ablaufrille 70 aus.

FIG. 3 represents an alternative embodiment of a control valve 22 in conjunction with a screw 66. For the control valve 22 apply in principle the same statements as the control valve 22 according to the FIG. 2 , It is therefore only briefly to discuss the differences. First, the diameter of the head portion 42 of the intermediate member 44 has been reduced. On the other hand, an outlet throttle 68 was formed in the outlet channel 18. Finally, the end faces of the intermediate element 44 and the guide element 24 lie against one another in such a way that the parting line 56 is now below

• based on the figure of the sealing seat 28 is located. The aforementioned end faces form a drainage groove 70 here.

The threaded bandage 66 has a magnetic clamping nut 72 and a sleeve 74. The magnetic clamping nut 72 has a first thread 76, which engages in a second thread 78 of a holding body 80. The sleeve 74 seals the leakage oil chamber 20 relative to the holding body 80 with a sealing ring 82. At the top of the sleeve 74 overmolded tabs 84 are arranged, which serve the electrical contacting of the magnetic coil 34.

In FIG. 4 It is shown that the intermediate element 44 and the guide element 24 can also be made in one piece. In this case, the guide member 24, with which the intermediate member 44 is integrally formed, is supported on the holding body 80 or on a base connected to the holding body 80. The parting line 56 is then so at the lower end of the guide member 24th

In the figures, adjusting elements for the valve spring force are not shown in detail. Advantageously, between the intermediate element 44 and the valve spring 48, an adjustment be provided for the valve spring force. In the adjustment, it may be in the embodiment according to FIG. 2 around a ring or in the embodiment according to FIG. 3 to act as a sickle disk. In the latter embodiment, the sickle plate is advantageous because the valve spring 48 are pushed over the intermediate element 44 during assembly from above and later but must be supported on the end face. A sickle disk can compensate for the diameter jump here.

Claims (9)

1. Fuel injection valve (10) for internal combustion engines, having a valve needle (14) which, by means of its longitudinal movement, controls the opening of at least one injection opening, and having a control chamber (16), the pressure of which acts at least indirectly on the valve needle (14) and which can be connected by means of a discharge duct (18) to a leakage oil chamber (20), and having a control valve (22) which is designed for opening and closing the discharge duct (18), with the control valve (22) having an actuating element (26) which is held in a movable manner on a guide element (24) and which is acted on with a force in the direction of a sealing seat (28), and having an actuator (30) for raising the actuating element (26) from the sealing seat (28), characterized in that an intermediate element (44) is arranged between the actuator (30) and the guide element (24) in such a way that a mechanical hold-down force which acts on the actuator (30) is introduced via the intermediate element (44) into the guide element (24), and in that the actuating element (26) is acted on with a force in the direction of the sealing seat (28) by means of a valve spring (48), and the valve spring (48) is supported on a head section (42) of the intermediate element (44) and on the actuating element (26).
2. Device according to Claim 1, characterized in that the intermediate element (44) bears against a narrowed region (38) of a recess (36) in the actuator (30).
3. Device according to Claim 1 or 2, characterized in that the narrowed region (38) is formed as a diameter step.
4. Device according to Claim 2 or 3, characterized in that the intermediate element (44) has a head section (42) which bears against at least one end surface (40) of the narrowed region (38).
5. Device according to Claim 4, characterized in that the head section (42) has discharge bores (46).
6. Device according to one of Claims 1 to 5, characterized in that a parting joint (56) is formed between the guide element (24) and the intermediate element (44), which parting joint (56) is situated below the sealing seat (28) in relation to a direction from the guide element (24) to the actuator (30).
7. Device according to one of Claims 1 to 6, characterized in that the guide element (24) and the intermediate element (44) bear against one another at a respective end surface (52, 54), with a discharge channel (70) or a part of a discharge channel (70) being formed in at least one of the end surfaces (52, 54).
8. Device according to one of Claims 1 to 7, characterized in that a non-magnetic armature stroke adjusting element and/or a non-magnetic residual air gap adjusting element is arranged between the guide element (24) and the intermediate element (44) and/or between the intermediate element (44) and the actuator (30).
9. Device according to one of Claims 1 to 8, characterized in that central axes (60, 62, 64) of the guide element (24), of the intermediate element (44) and of the actuator (30) are aligned with one another.

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