EP1256708A2 - Fuel injection device for an internal-combustion engine - Google Patents

Abstract

The fuel injection device (10) includes a casing (11) with a closed injection end (22) and with a recess (18, 20) running along it. There are two axial outlets at the injection end. The device has its compression cavities (e.g. 34) connected by a common control channel (32) differentiating the opening pressure of one of the valve elements (36) from the other (38).

Description

State of the art

The present invention relates to a fuel injection device for internal combustion engines, with one elongated housing with a closed injection end, with one in the longitudinal direction of the housing extending recess, which with a fuel inlet is connectable with at least two axially from each other spaced outlet openings at the injection end, with at least two coaxial valve elements in the Recess are arranged and each of at least one Preload element against a corresponding valve seat in the Area of the outlet openings are applied, wherein the valve elements each have at least one pressure surface have, which delimits a pressure chamber and so aligned is that their pressurization is an axial movement of the corresponding valve element can cause.

Such a fuel injector is from the DE 40 23 223 A1 known. In this is a fuel injector shown for internal combustion engines. Two Valve needles are arranged coaxially with one another. Both Valve needles are approximately half way up Printing area on. The printing areas of the respective Valve needles are each with a flow channel connected by a hydraulic fluid, for example Fuel or oil that can flow to the pressure surface. The Print areas are aligned so that with a Pressurizing the valve needles from each of them Lift off the assigned seat and thereby corresponding Open the outlet openings at the end of the injection nozzle. Via the two independent flow channels the valve needles can be controlled independently become.

The object of the present invention is a fuel injection device for internal combustion engines of the beginning the kind mentioned so that it builds easier, has smaller dimensions and overall cheaper is to be produced.

This task is accomplished with a fuel injector of the type mentioned above solved that the pressure rooms with a common Control channel are connected, and the opening pressure one valve element from that of another valve element different.

Advantages of the invention

In the fuel injection device according to the invention is only a connection to a high pressure supply required. This allows the fuel injector build smaller overall. About that furthermore there are no different flow channels required, which lead to the respective printing areas, and there is also no seal between the individual Printing areas necessary. Instead, the amount of Pressure in the control channel determines how many valve elements be moved. This enables a simpler setup with fewer parts, which ultimately lowers manufacturing costs.

Advantageous developments of the invention are in Subclaims specified.

In a first training it is mentioned that the Pressure spaces on the corresponding valve seat End of the valve elements are formed. This offers itself then when it is the fluid that is moving the valve elements should act to fuel. Then the fuel intended for injection can at the same time for the control of the valve elements be used.

It is particularly preferred that the printing surfaces each by at least one conical taper on the the valve seat facing end of a valve element are formed. Such is a conical taper especially with fuel injectors, which are designed as a seat hole nozzle, particularly simple to manufacture and deliver without additional complex Measures or processing steps a printing area whose Acting on an axial opening movement of the corresponding valve element leads.

The amount of fuel injected by the fuel injector dispensed fuel can on can be easily adjusted by setting the At least one fuel injector at the end of the injection two axially spaced rows from across the Scope of the injection end distributed outlet openings having. Depending on the number and size of the outlet openings becomes a more or less large amount of fuel of the fuel injector.

The setting of the opening pressure of one of the valve elements can by the biasing forces of the biasing elements happen. This is through continuing education Fuel injection device according to the invention expressed at which the preload forces of the Differentiate preload elements.

Alternatively or in addition to this, the size can also change the printing area of an element the size of Distinguish the pressure area of another valve element. This also results in different opening pressures of one valve element to another.

One way of applying the prestressing forces is that the biasing elements a Include coil spring and / or a gas spring. such Preload elements are simple and reliable in operation.

In a preferred embodiment, it is also proposed that the outer valve element at its from the valve seat remote end is connected to a support ring on which that assigned to the outer valve element Prestressing element supports. This represents a reliable and easy to establish mechanical connection between Prestressing element and valve element.

It is particularly preferred that the outside Valve element assigned in its Longitudinal direction has a through opening through which an end connected to the inner valve element Section runs through. This enables the Preload elements of the individual valve elements in axial Arranged one behind the other, which in turn the radial dimensions of the fuel injection devices according to the invention lowers.

To defined conditions in the open state of the To get fuel injector suggested that they have a mechanical stop which has the path during an opening movement limited at least one of the valve elements. hereby will also overshoot the corresponding Valve element avoided during the opening process.

To the cost of producing the invention Fuel injector will reduce suggested that at least the housing and the Preload elements identical to the housing and the Biasing elements of a conventional fuel injector which are just a valve element includes.

Figur 1

einen teilweisen Längsschnitt durch eine Kraftstoff-Einspritzvorrichtung;

Figur 2

einen vergrößerten Ausschnitt II der Kraftstoff-Einspritzvorrichtung von Figur 1;

Figur 3

einen vergrößerten Ausschnitt III der Kraftstoff-Einspritzvorrichtung von Figur 1; und

Figur 4

einen vergrößerten Ausschnitt IV des in Figur 3 dargestellten Bereichs der Kraftstoff-Einspritzvorrichtung.

An exemplary embodiment of the invention is explained in detail below with reference to the accompanying drawing. The drawing shows:

Figure 1

a partial longitudinal section through a fuel injection device;

Figure 2

an enlarged section II of the fuel injection device of Figure 1;

Figure 3

an enlarged section III of the fuel injection device of Figure 1; and

Figure 4

an enlarged section IV of the area of the fuel injection device shown in Figure 3.

Description of the embodiment

A fuel injection device carries in Figure 1 overall reference number 10. The fuel injector 10 is used to inject Fuel in the combustion chamber of an internal combustion engine. As Fuel is petrol or diesel. The assembly can be done directly on the internal combustion engine. it includes an elongated housing 11, which consists of an upper Base section 12, a nozzle body 14 and one Connection sleeve 16 is made. The base section 12 is from a step-shaped longitudinal bore 18 passes through. in the Nozzle body 14 is a blind hole 20, which is from the upper edge of the nozzle body 14 to one in the Figures 1 to 4 provided at the bottom of the injection cap 22 extends. The injection tip 22 is down closed and has two axially spaced apart Rows of outlet openings 24 distributed over the circumference or 26 on.

Is between the nozzle body 14 and the base portion 12 an intermediate piece 28 through the connecting sleeve 16 braced. In the intermediate piece 28 there is also a step-shaped one Through opening 30 available. The longitudinal bore 18 in Base section 12, the blind hole 20 in the nozzle body 14 and the through opening 30 in the intermediate piece 28 are aligned Installation position with each other. The base section 12 and that Intermediate piece 28 are from a flow channel 32nd enforces itself in the nozzle body 14 up to one annulus-like pressure chamber 34 in the blind hole 20 of the Nozzle body 14 continues.

In the blind hole 20 of the nozzle body 14 there is first a exterior provided with a continuous longitudinal bore Valve element 36 arranged. In the longitudinal hole (without Reference numeral) in the outer valve element 36 is an inner one Valve element 38 introduced. The two valve elements 36 and 38 are arranged coaxially with each other. At his the Injection cap 22 facing the end Valve element 36 has a conical taper through which an annular pressure surface 40 is formed. A pressure space 41 is located upstream from the printing surface 40 available.

Furthermore, is also at the level of the pressure chamber 34 in the outer Valve element 36 a step with a conical taper present, which forms a further printing surface 42. Below the lower pressure surface 40 is on the outside Valve element 36 formed a sealing edge 44, which with a valve seat (without reference number) on the inner wall of the Blind holes 20 cooperates in the nozzle body 14. The The sealing seat is above the upper one Injection orifices 24 (it should be at this point noted that the designation "top" and "bottom" at the description of this embodiment itself exclusively on the representation in FIGS. 1 and 4 refers; it is understood that the one described here Fuel injector 10 in any Location, for example, mounted on an internal combustion engine can be).

In the rest position shown in Figures 1 to 4 Fuel injector 10 faces the lower end of the inner valve member 38 over the lower end of the outer valve element 36 over. At the protruding end inner valve member 38 is also a conical one Taper is present, which forms a pressure surface 46. Below the pressure surface 46 there is also a sealing edge 48 provided with a valve seat on the inner wall of the Blind holes 20 cooperates in the nozzle body 14. A pressure space 47 is located upstream from the pressure surface 46 available.

The valve seat for the sealing edge 48 is in the axial Direction seen between the lower injection openings 26 and the upper injection ports 24. Let it be on this Pointed out that in the resting position of the Fuel injector 10, the sealing edges 44 and 48 rest on the respective valve seats. Out For reasons of illustration, a gap between the Sealing edges 44 and 48 and the respective valve seats shown.

In the rest position shown per se in FIGS. 1 to 4 closes the upper end of the outer valve member 36 in approximately flush with the top of the nozzle body 14 (cf. Figure 2). In the through opening 30 in the intermediate piece 28 a translator piece 50 is used, which one Section 52 with a larger diameter and a section 54 has a smaller diameter. The face of the Section 52 abuts the end face of the outer Valve element 36 on. Section 54 says that Translator piece 50 over the intermediate piece 28 over.

On the face of section 54 of the translator piece 50 an intermediate ring 56 is supported, on which in turn a helical compression spring 58 is supported. The other end is supported on a clamping piece 60, which in the Longitudinal bore 18 in the base section 12 approximately on the latter half way up. About the intermediate ring 56 and that Translator piece 50 becomes the biasing force of the Coil spring 58 on the outer valve element 36 transferred and this thereby with its sealing edge 44th against the associated valve seat in the injection cap 22 pressed.

Between section 52 and section 54 of the Translator piece 50, a paragraph 62 is formed. At the same time, the stepped bore 30 shows Intermediate piece 28 has a shoulder 64 to 4 and in particular shown in Figure 2 idle state the fuel injector 10 in which the Sealing edge 44 of the outer valve element 36 den touches the corresponding valve seat on the nozzle body between paragraph 62 on translator piece 50 and level 64 at the intermediate piece 28 there is a gap, the size S1 is. The maximum stroke of the outer valve element is therefore also S1.

In the translator piece 50 is also a step trained through hole 66 present. The stage this bore 66 has the reference number 67. The inner Valve element 38 protrudes around one with its upper end Distance S2 over the upper end of the outer valve element 36 over and something in the larger diameter section the through hole 66 in the translator piece 50. At the upper end of the inner valve element 38 lies with a disk-shaped end section 68, a booster piston 70 on.

The translation piston 70 extends through the Through hole 66 in the translator 70, the recess in the intermediate ring 56 and a recess (without reference numerals) in the clamping piece 60. At its upper end in Figure 1 is a support plate 72 on the booster piston 70 attached to one end of a helical Compression spring 74 supports. The other end of the coil spring 74 is based on a paragraph (without reference numerals) of the Longitudinal bore 18 in the base section 12.

In the idle state shown in Figures 1 to 4 Fuel injector 10 is the end portion 68 of the booster piston 70 is not yet at the stage 67 between the larger section Diameter and the smaller diameter section of the Through hole 66 is formed in the translator piece 50. The distance S2 is also in said idle state slightly larger than the distance S1. That way ensures that when opening the outer Valve element 36 this not at the end section 68 of the Translator piston 70 stops. Otherwise, this would be too an unwanted relief of the inner valve element 38 to lead. The shoulder 64 and the shoulder 62 thus form one Stop for the opening movement of the outer Valve element 36.

The fuel injection device shown in Figures 1 to 4 10 is operated as follows: In Idle state, that is, in that state of the fuel injection device 10 by taking no fuel from this is released, the sealing edges 44 and 48 of the outer valve element 36 or inner valve element 38 sealing on the respective valve seats on the inside of the blind hole 20 in the area of the injection tip 22. The in the annular space between the outer valve element 36 and the blind hole 20 in the nozzle body 14 existing fuel can therefore not via the injection openings 24 and 26 escape.

Should now be an injection with a relatively low Amount of fuel is not made by one shown pressure supply unit a pressure pulse generated, which extends through the flow channel 32 to Pressure chamber 34 and the annular space between the outer Valve element 36 and the blind hole 20 in the nozzle body 14 continues. From there the pressure pulse reaches the Pressure chamber 41. The level of the pressure pulse is so dimensioned that on the printing surfaces 40 and 42 of the outer valve element 36 resulting axial force to a Opening movement of the outer valve element 36 leads. As a result, the sealing edge 44 of the outer valve element lifts 36 from the corresponding valve seat, so that fuel via the injection openings 24 from the fuel injection device 10 can be delivered.

However, the pressure of the pressure wave is so low that that inner valve element 38 does not open. This will do so causes on the one hand the pressure surface 46 on the inside Valve element 38 is smaller than the sum of the pressure areas 40 and 42 of the outer valve element 36. On the other hand but also by a stronger spring preload Compression spring 74 reached in comparison to the compression spring 58. To At the end of the pressure pulse, the pressure in the pressure chamber 34 drops and in the pressure chamber 41 again, so that the outer Valve element 36 due to the bias by the Coil spring 58 moved back down and the Sealing edge 44 in contact with the corresponding valve seat arrives.

If fuel injection is desired at the more fuel from the fuel injector 10 is released, a correspondingly higher pressure pulse generated. This pressure pulse results in the one described above Way first to an opening of the outer Valve element 36 until the translator piece 50 is the Line S1 has moved and with paragraph 62 on the shoulder 64 strikes in the intermediate piece 28. Because of the open outer valve element 36 can now also in the pressure pulse reach the pressure chamber 47 and on the pressure surface 46 of the attack inner valve member 38.

The level of the pressure pulse is chosen so that the on the pressure surface 46 of the inner valve element 38 resulting axial force is greater than the closing force of the Compression spring 74. This leads to an opening movement of the inner valve member 38 through which the injection ports 26 are ultimately connected to the flow channel 32. Through the injection openings 24 and the injection openings 26 can now fuel from the fuel injector 10 exit.

The opening movement of the outer valve element 36 will thereby by the between the translator 50 and the Intermediate piece 28 formed stop 62 and 64 limited. The opening path of the outer valve element 36 is maximum S1. The opening movement of the inner valve element 38 is by the between the end portion 68 of Translator piston 70 and level 67 in translator piece 50 formed stop limited. The opening path of the interior Valve element is also a maximum of approximately S1.

Claims (11)

Fuel injection device (10) for internal combustion engines, with an elongated housing (11) with a closed injection end (22), with a recess (20) running in the longitudinal direction in the housing (11), which has a fuel inlet (32) can be connected, with at least two axially spaced outlet openings at the injection end (22), with at least two coaxial valve elements (36, 38) which are arranged in the recess (20) and each with at least one biasing element (58, 74) a corresponding valve seat is acted upon in the area of the outlet openings (24, 26), the valve elements (38, 38) each having at least one pressure surface (40, 42, 46) which delimits a pressure chamber and is oriented in such a way that its pressure is applied axially Can cause movement of the corresponding valve element (36, 38), characterized in that the pressure chambers are connected to a common control channel (32) nd and the opening pressure of one valve element (36, 38) differs from that of another valve element (38, 36). Fuel injection device (10) according to Claim 1, characterized in that the pressure spaces are formed at the end of the valve elements (36, 38) facing the corresponding valve seat. Fuel injection device (10) according to Claim 2, characterized in that the pressure surfaces (42, 46) are each formed by at least one conical taper at the end of a valve element (36, 38) facing the valve seat. Fuel injection device (10) according to one of the preceding claims, characterized in that it has at the injection end (20) at least two axially spaced rows of outlet openings (24, 26) distributed over the circumference of the injection end (20). Fuel injection device (10) according to one of the preceding claims, characterized in that the biasing forces of the biasing elements (58, 74) differ. Fuel injection device (10) according to one of the preceding claims, characterized in that the size of the pressure surface (40, 42) of one element (36) differs from the size of the pressure surface (46) of another valve element (38). Fuel injection device (10) according to one of the preceding claims, characterized in that the biasing elements comprise a helical spring (58, 74) and / or a gas spring. Fuel injection device (10) according to one of the preceding claims, characterized in that the outer valve element (36) is connected at its end remote from the valve seat to a support ring (56) on which the biasing element (36) associated with the outer valve element (36) 58) supports. Fuel injection device (10) according to claim 8, characterized in that the biasing element (58) associated with the outer valve element (36) has in its longitudinal direction a through opening through which an end section (70) connected to the inner valve element (38) passes runs. Fuel injection device (10) according to one of the preceding claims, characterized in that it has a mechanical stop which limits the path during an opening movement of at least one of the valve elements (36, 38). Fuel injection device (10) according to one of claims 9 or 10, characterized in that at least the housing (11) and the biasing elements (58, 74) are identical to the housing and the biasing elements of a conventional fuel injection device, which is only a valve element includes.

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