EP1407134B1 - High-pressure fuel device - Google Patents

Description

State of the art

The invention is based on a high-pressure fuel device according to the preamble of claim 1. Such High-pressure fuel device is in the form of a fuel injection valve known from DE 198 27 267 A1 and includes a housing having a first as a valve holding body trained high-pressure body and a second as a valve body trained high-pressure body includes. The two High-pressure bodies lie against each other in a contact surface. Through the contact surface enters a high-pressure chamber in the form of a High-pressure channel through, the fuel under high pressure leads. The housing is in the area of the contact surface of a surrounded by a substantially cylindrical wall part, which is designed as a clamping nut and has a longitudinal axis. Between the housing and the clamping nut is a Leakage oil space is formed, which covers the housing on its entire Circumference surrounds.

The patent US 6,047,899 is also a High-pressure fuel device in the form of a fuel injection valve known, wherein the fuel injection valve more High-pressure body comprises. The high pressure bodies are with a Clamping nut pressed together, being between the high pressure bodies and the clamping nut a room with a low Fuel pressure is present. The clamping nut is with a Internal thread on a corresponding external thread on a high-pressure body screwed on while the clamping nut on another High pressure body rests against a shoulder. For sealing The space is outside the thread and facing away from the shoulder a sealing ring provided in an annular groove on a high-pressure body is inserted.

In the known high-pressure fuel device occurs Disadvantage of that there are leaks in the area of the contact surface can come. The high pressure room will be at his Passing through the contact surface only by the surface pressure the body is sealed to each other in the contact surface abut and surround the passage of the high-pressure chamber. As in the high-pressure chamber sometimes very high pressures of 120 MPa and can prevail over this seal is not completely, causing it to leak fuel in the contact surface can come into the leakage oil space between the clamping nut and the housing reaches, from where it is longer Operation of the high-pressure fuel device finally exit. This can be when used in an internal combustion engine cause significant damage, especially if this Fuel gets into the engine compartment and there by hot Components is set on fire.

Advantages of the invention

The high-pressure fuel device according to the invention with the Characteristic features of claim 1, in contrast the advantage that even at leaks the contact surface of the two high-pressure body no fuel can get outside. For this purpose, the leakage oil space, formed between the housing and the wall part is sealed. The fuel between the high pressure bodies passes through the contact surface remains so in the leakage oil chamber, and the high-pressure fuel device is sealed to the outside.

Between the wall part and the first high pressure body is formed a first sealing connection and between the wall part and the second high pressure body a second sealing connection. This will cause the leakage oil space sealed in a simple manner and sealing both Connections can be made independently.

The wall part is designed as a clamping nut, which is the high pressure body pressed together on the contact surface. In this way becomes the function of sealing to the outside and the function a clamping element for pressing together the high-pressure body united in only one component.

At least a sealing connection of the Wandungssteils is with the housing arranged by a between the housing and the wall part Formed sealing ring. This can be a good one Tightness can be achieved, and the sealing ring can be attached to different Be adapted to circumstances.

In an advantageous embodiment of the article the invention is the leakage oil chamber with a in the housing trained low-pressure space, wherein in the low pressure space always maintained a low fuel pressure becomes. Over this connection the fuel can out drain the leakage oil space and it does not come with time a pressure accumulation in the leakage oil space, resulting in leaks of could cause sealing connections.

In a further advantageous embodiment, one of sealing connections of the clamping nut with the housing by the installation of a sealing surface on a housing formed on the Formed contact surface. In this embodiment can be applied by the clamping nut pressure force for one of the sealing connections can be used without additional sealing or clamping elements would be necessary.

In a further advantageous embodiment of the sealing ring made of an elastic material, preferably a plastic or elastomer. Such a sealing ring can by deforming the space between the wall part and adapt to the housing and thereby seal securely.

In a further advantageous embodiment of the sealing ring Made of polytetrafluoroethylene (PTFE), what next the good tightness offers the advantage that the sealing ring chemically extremely resistant and by the fuel not attacked. In addition, PTFE is good heat resistant and is therefore particularly suitable for use in fuel injection valves, exposed to high temperatures are.

Particularly advantageous is the high-pressure fuel device according to the invention, when acting as a fuel injector is designed for internal combustion engine, since the occurring here Leakage problems due to measures on the contact surface can not be resolved finally. It revealed Here are some other advantages: The requirements for the Quality of the sealing surfaces of the two high-pressure body is clear reduces, as a certain amount of leakage to the outside in the leakage oil space is acceptable. In addition, results the advantage that the high-pressure body with less force must be pressed together, resulting in a reduction the mechanical tension in the fuel injector leads and thus to lower deformations, otherwise affect the function of the fuel injection valve can.

Further advantages and advantageous embodiments of the invention are the description and the drawing removable.

drawing

Figur 1 eine nicht erfindungsgemäße Kraftstoffhochdruckvorrichtung in Form eines Kraftstoffeinspritzventils im Längsschnitt.

Figur 2 zeigt eine Vergrößerung des mit II bezeichneten Ausschnitts von Fig. 1. Figur 3 zeigt ein erfindungsgemäßes Ausführungsbeispiel des mit III bezeichneten Ausschnitt der Fig. 1 und Figur 4 eine Vergrößerung im Bereich der Anlagefläche eines weiteren erfindungsgemäßen Ausführungsbeispiels.

In the drawing, an example of a high-pressure fuel device is shown. It shows

Figure 1 is a non-inventive high-pressure fuel device in the form of a fuel injection valve in longitudinal section.

FIG. 2 shows an enlargement of the section of FIG. 1 denoted by II. FIG. 3 shows an exemplary embodiment according to the invention of the section of FIG. 1 designated by III and FIG. 4 shows an enlargement in the area of the contact surface of a further embodiment according to the invention.

Description of the embodiments

In Fig. 1 is an example of a Fuel high-pressure device in longitudinal section in his essential parts. The here as fuel injector trained high-pressure fuel device comprises a housing 1 having a first high pressure body, which is designed as a valve holding body 3, and a second high-pressure body, the valve body as the fifth is formed comprises. The valve holding body 3 is applied a contact surface 30 on the valve body 5 and is by means of designed as a wall part clamping nut 7 against pressed this. In the valve body 5, a bore 8 is formed, which has a longitudinal axis 15, which also with the Longitudinal axis 15 of the clamping nut 7 coincides. In the hole 8, a piston-shaped valve needle 10 is longitudinally displaceable arranged in a combustion chamber facing away from the section is guided sealingly in the bore 8 and the the combustion chamber tapers to form a pressure shoulder 21. At the combustion chamber end, the valve needle 10 goes in a substantially conical valve sealing surface 14 over, the formed with a combustion chamber end of the bore 8 Valve seat 16 cooperates, which is also substantially is conically shaped and the approximately the same opening angle as the valve sealing surface 14 has. In the valve seat 16, a plurality of injection openings 12 are formed, the valve seat 16 with the combustion chamber of the internal combustion engine connect. At the height of the pressure shoulder 21 is through a radial extension of the bore 3, a pressure chamber 18 is formed, the one about in the valve body 5 and the valve holding body 3 trained inlet channel 23 with fuel can be filled under high pressure. The inlet channel 23 forms a high-pressure chamber and passes through the contact surface 30 of the two high-pressure body 3, 5 through. The pressure chamber 18 sets to the valve seat 16 as a valve needle 10 surrounding Ring channel 19 continues, allowing fuel from the pressure chamber 18 can flow to the valve seat 16. When plant the Valve sealing surface 14 on the valve seat 16 are the injection openings 12 closed, and there is no fuel from the annular channel 19 to the injection openings 12th Lift the valve sealing surface 14 by a longitudinal movement of the Valve needle 10 from the valve seat 16, so fuel flows from the annular channel 19 through the between the valve sealing surface 14 and the valve seat 16 formed gap to the injection openings 12, and fuel is in the combustion chamber of the Internal combustion engine injected.

The valve body 5 is in the area in which the valve needle 10 is guided, formed with a cylindrical outer surface, the the combustion chamber to about the height of the pressure chamber 18 tapers to form a contact surface 44, wherein the contact surface 44 in a radial plane to the bore. 8 lies. The clamping nut 7 is substantially as a hollow cylinder formed and surrounds the valve body 5 and a part the valve holding body 3, in particular in the region of the contact surface 30. At its combustion chamber end facing the Clamping nut 7 a collar on which a sealing surface 42nd is formed, which comes to the contact surface 44 to the plant and a first sealing connection between the clamping nut 7 and the housing 1 forms. In the combustion chamber facing away end the clamping nut 7 has an internal thread 38, the in a on the outer circumferential surface of the valve holding body. 3 trained external thread 36 engages. By turning the Clamping nut 7 is screwed to the valve holding body 3 and thereby shifts longitudinally, so the sealing surface 42 is pressed against the contact surface 44 is and the valve body 5 in the contact surface 30 against the Valve holding body 3.

Between the clamping nut 7 and the valve holding body 3 respectively the valve body 5 is formed a leakage oil space 30, the at the combustion chamber end area through the plant the sealing surface 42 sealed to the contact surface 44 becomes. In Brennraumabgewandten end of the clamping nut. 7 the sealing is effected by a sealing ring 50, the between the clamping nut 7 and the valve holding body 3 is clamped is and thus forms a second sealing connection. Fig. 2 shows for clarity an enlargement of II designated area of Fig. 1, where the sealing ring 50 in Cross section is shown. The sealing ring 50 is made of an elastic Material manufactured, for example, from rubber or a plastic, so that it can deform accordingly and a sealing connection of the clamping nut 7 with the valve holding body 3 creates. Especially polytetrafluoroethylene This is advantageous because this plastic largely is chemically inert. The leakage oil space 30 is thus sealed, and it can not get fuel out.

Facing away from the combustion chamber, the bore 8 goes into a valve holding body 3 trained piston bore 26 via, at the transition has a slightly larger diameter than the bore 8. In the piston bore 26, a pressure piece 25 is arranged, the end face of the valve needle facing away from the combustion chamber 10 is present. The pressure piece 25 is followed Valve piston 27, which is also in the piston bore 26th is guided and arranged coaxially with the valve needle 10. The valve piston 27 may have a closing force via the pressure piece 25 exert on the valve needle 10, so that with its valve sealing surface 14 pressed against the valve seat 16 becomes. In the piston bore 26 is beyond a Closing spring 28 is arranged, which faces away from the valve needle 10 supported on a ring shoulder 29 and with their other End on the pressure piece 25. Since the closing spring 28 is pressure-biased is, it exerts a closing force on the valve needle 10 off, these - especially when not running internal combustion engine - Holds in its closed position. The piston bore 26 is shown with a not shown in the drawing Leakage oil system connected so that the piston bore 26 a Low pressure space forms, in which always a lower Fuel pressure prevails. About the annular gap between the Valve needle 10 and the wall of the hole 8 can only very little Fuel from the pressure chamber 18 in the piston bore 26th arrive, which then immediately drained into the drain system becomes.

The movement of the valve needle 10 in the bore 8 and thus the control of the timing and duration of the injection takes place in the way that the closing force on the valve needle 10 is controlled. By one in the drawing not shown device is facing away from the combustion chamber End of the valve piston 27 exerted a force which is controllable is. About the inlet channel 23 is by a in the drawing also not shown high pressure fuel source passed under high pressure in the pressure chamber 18, wherein during of the entire operation a given high pressure in Pressure chamber 18 is maintained. By the fuel pressure in the pressure chamber 18 and thus also in the annular channel 19 results a hydraulic force on the pressure shoulder 21 and on parts of the valve sealing surface 14, the closing force of Counteract valve piston 27 and closing spring 28. Reduced one the closing force on the valve needle 10, so predominates the hydraulic opening force, and the valve needle 10th lifts with the valve sealing surface 14 from the valve seat 16, so that fuel can flow to the injection openings 12. If the closing force is increased again so far that they are larger as the opening force is, the valve needle shifts 10 again in the direction of the valve seat 16 and the injection openings 12 are closed.

By constantly prevailing in the inlet channel 23 high Fuel pressure is due to the tightness of the contact surface the two high-pressure body 3; 5 very high requirements, so that from the inlet channel 23 no fuel between the valve body 5 and the valve holding body 3 exits. The part of the fuel going inside the piston bore 26 passes, is derived from there into the drain system and interferes with the operation of the fuel injection valve Not. To the outside flowing into the leakage oil space 32 Fuel is held there, leaving the fuel injector is tight to the outside. However, it flows more fuel in the leakage oil chamber 32, so there may be a pressure pad build up what will sooner or later lead to a leak lead either on the sealing ring 50 or on the sealing surface 42 becomes. To prevent this is at the valve body. 5 facing end face of the valve holding body 7, a connecting channel 34 formed in the form of a groove which the leakage oil space 32 connects to the piston bore 26. The fuel in the leakage oil chamber 32 can thus drain and the leakage oil chamber 32nd remains pressureless.

Fig. 3 shows an enlargement of Fig. 1 in III designated Detail of an embodiment of the invention. The sealing ring 50 is not here at the end of the clamping nut. 7 arranged, but is located in an annular groove 52, the surrounds the valve holding body 3 on its entire circumference. The annular groove 52 is arranged in the external thread 36, so that seen in the direction of the longitudinal axis 15 on both Side of the annular groove 52 is a part of the external thread 36. The sealing ring 50 is before screwing the clamping nut 7 arranged in the annular groove 52, so that the Clamping nut 7 with the internal thread 38 when mounting over the sealing ring 50 moves. Since the sealing ring 50 of a elastic and easily deformable material is deformed the clamping nut the sealing ring 50 and intersects with the Internal thread 38 in the sealing ring 50 a. This will be a very tight connection between clamping nut 7 and sealing ring 50 reached.

Fig. 4 shows a further embodiment of the invention Fuel injection valve in a cutout in the region of the contact surface 30. The connecting channel 34 is not here as a groove in an end face of the valve holding body 3 formed, but as a bore in the valve holding body 3, with the longitudinal axis 15 an angle of, for example 45 °. The connecting channel 34 can in this case of emanating from any point of the leakage oil space, so that the remaining functional elements are not affected.

In the drawing, only two high-pressure bodies are present, namely the valve holding body 3 and the valve body 5. Es But it can also be provided that between these two Bodies are arranged more high-pressure body, for example in the form of washers. This allows multiple contact surfaces be formed, all of the clamping nut. 7 are surrounded, so that emerging from the contact surfaces Fuel is dissipated without leaving the fuel injector to get outside.

In addition to the arrangement of a leakage oil space according to the invention It can also be provided to a fuel injection valve be a wall part on every other high-pressure fuel device to use in which a high pressure room with Fuel under high pressure through the contact surface of two High pressure body passes. The leakage oil space can also be in In this case, connected to a corresponding leakage oil system become.

Claims (6)

1. High-pressure fuel device having a housing (1), which comprises a first high-pressure body (3) and a second high-pressure body (4), which bodies bear against each other at a bearing surface (30) and through which bearing surface (30) passes a high-pressure space (23) which is formed in the housing (1) and in which there is at least temporarily a high fuel pressure, and having a sleeve-shaped wall part (7) which has a longitudinal axis (15) and, on the outer circumferential surface, surrounds the housing (1) at least in the region of the bearing surface (30), with the result that a leakage oil space (32) is formed between the wall part (7) and the housing (1), the leakage oil space (32) being sealed off to the outside, and two sealing connections being formed between the wall part (7) and the housing (1), one sealing connection being formed between the wall part (7) and the first high-pressure body (3) and the second sealing connection being formed between the wall part (7) and the second high-pressure body (5), the wall part being a clamping nut (7) which engages in an outer thread (36) formed on the housing (1) and thus presses the two high-pressure bodies (3; 5) against each other, characterized in that at least one sealing connection of the wall part (7) to the housing (1) is formed by a sealing ring (50) which is arranged between the housing (1) and the wall part (7) and is arranged in an annular groove (52) formed in the outer thread (36).
2. High-pressure fuel device according to Claim 1, characterized in that a low-pressure space, in which a significantly lower pressure prevails than in the high-pressure space (23) and which is connected to the leakage oil space (32), is formed in the housing (1).
3. High-pressure fuel device according to Claim 1, characterized in that one of the sealing connections of the wall part (7) to the housing (1) is formed by a sealing surface (42), which is formed on the wall part (7), bearing against a bearing surface (44), which is formed on the housing (1).
4. High-pressure fuel device according to Claim 1, characterized in that the sealing ring (50) consists of an elastically deformable material, preferably a plastic or an elastomer.
5. High-pressure fuel device according to Claim 4, characterized in that the sealing ring (50) consists of polytetrafluoroethylene or a polytetrafluoroethylene-containing plastic.
6. High-pressure fuel device according to one of the preceding claims, characterized in that the high-pressure fuel device is designed as a fuel injection valve for internal combustion engines.

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