WO2003046367A1

WO2003046367A1 - Fuel injection valve for internal combustion engines

Info

Publication number: WO2003046367A1
Application number: PCT/DE2002/002612
Authority: WO
Inventors: Sieghart Maier; Thomas Pauer
Original assignee: Robert Bosch Gmbh
Priority date: 2001-11-13
Filing date: 2002-07-17
Publication date: 2003-06-05
Also published as: DE10155677A1

Abstract

The invention relates to a fuel injection valve for internal combustion engines comprising a housing (1), which has a first body (3) and a second body (5) that rest against one another via a contact surface (20). A high-pressure channel (10) is provided inside the bodies (3; 5). This channel passes through the contact surface (20) of both bodies (3; 5) and is filled with fuel that is highly pressurized at least at times. A sealing element (25) is provided inside the high-pressure channel (10) in the area of the contact surface (20). This sealing element can be elastically deformed and is pressed against the wall of the high-pressure channel (10) by the pressure of the fuel inside the high-pressure channel (10). This enables the high-pressure channel (10) to be sealed at the location where it passes through the contact surface (20) of both bodies (3; 5).

Description

Fuel injection valve for internal combustion engines

State of the art

The invention is based on a fuel injection valve for internal combustion engines, as is known, for example, from the published patent application DE 198 27 267 A1. The fuel injection valve described there has a housing, the housing comprising two bodies abutting one another, in which a high-pressure channel runs, which conveys fuel from a high-pressure source to an injection opening. The high-pressure channel passes through the contact surface of the two bodies. The two bodies are pressed against one another by a clamping nut on their contact surface, which is intended to ensure that the high-pressure duct is sealed at the passage through the contact surface of the two bodies. Since very high pressures of up to 200 MPa can occur in the high-pressure duct, this is not always the case. In order to improve the sealing of the high-pressure channel when passing through the contact surface, it is known from DE 198 27 628 AI to design the contact surface raised around the passage of the high-pressure channel in order to increase the local surface pressure in this area and thus also the tightness. However, the design of such a contact surface is complex and therefore cost-intensive. In addition, the sealing surface must be new in each of the different designs that occur with fuel injection valves can be adjusted to obtain the necessary properties.

Advantages of the invention

The fuel injection valve for internal combustion engines according to the invention has the advantage that the pressure in the inlet channel is used to reinforce the sealing of the high-pressure channel in the region of the passage through the contact surface of the two bodies. For this purpose, a sealing element is provided in the high-pressure channel in the area of the contact surface, which is designed to be elastic. Due to the pressure of the fuel, the elastic sealing element is pressed against the wall of the high-pressure duct, so that no fuel can get between the two bodies.

The object of the invention can be developed in an advantageous manner. In an advantageous embodiment, the elastic sealing element is designed in the shape of a hollow cylinder and lies with its outer circumferential surface against the wall of the high-pressure channel, one end of the elastic sealing element being arranged in the first body and the other end in the second body. The sealing element designed in this way is simple to manufacture, easy to assemble and offers a secure seal. In a further advantageous embodiment, the hollow cylindrical elastic sealing element is arranged in a radial extension of the high-pressure channel, so that it cannot move in the axial direction. This arrangement also has the advantage that the cross section of the high-pressure duct can be kept at least approximately constant, in order to avoid swirling of the fuel flowing through.

In a further advantageous embodiment, the annular gap that exists between the wall of the high-pressure duct and the outer surface of the elastic sealing element is connected via a connection channel formed in the housing to a fuel-filled leak oil chamber which is present in the housing and in which there is always a low pressure. As a result, there is always a pressure difference between the high-pressure duct and the annular gap between the wall of the high-pressure duct and the elastic sealing element, so that the sealing element is pressed against the outer wall of the high-pressure duct by the pressure in the high-pressure duct.

In a further advantageous embodiment, an annular space is formed between the outer circumferential surface of the elastic sealing element and the wall of the high-pressure duct, into which the connecting duct opens. This ensures that fuel that gets between the elastic sealing element and the wall of the high-pressure duct can flow into the leakage oil chamber via the connecting duct.

In a further advantageous embodiment, a ring shoulder is formed at the transition from the first to the second body in the high-pressure duct, on which the elastic sealing element bears with a contact surface. This ensures that the sealing element does not move in the longitudinal direction in the high-pressure duct.

In a further advantageous embodiment, the sealing element is rotationally symmetrical and at least approximately has an L-shaped longitudinal section. Together with the system on the ring shoulder, a contact force of the sealing element is obtained both against the contact surface and against the wall of the high-pressure duct, so that a secure seal is ensured.

In a further advantageous embodiment, the elastic sealing element is arranged in a recess which is delimited by a first and a second ring surface. The Sealing element has a first and a second contact surface, which come to rest on the first and second ring surface and are pressed against the ring surfaces by the pressure in the high-pressure channel. The first ring surface is arranged in the first body and the second ring surface in the second body, so that in addition to the sealing by the radial contact force against the wall of the high-pressure duct, an additional sealing is achieved by pressing the contact surfaces against the ring surfaces.

In a further advantageous embodiment, the elastic sealing element is toroidal and has a cavity which is connected to the high-pressure duct via openings. As a result, fuel can flow from the high-pressure channel through the openings into the cavity of the sealing element and inflate it. As a result, the toroidal sealing element is pressed against the limits of the radial expansion and thereby seals reliably.

In a further advantageous embodiment, the elastic sealing element consists of a plastic, preferably an elastomer. This ensures a high level of deformability and a sealing fit of the elastic sealing element against the wall of the high-pressure duct. In order to counteract the deformations that occur at very high pressures in the high-pressure duct, the elastic sealing element can also consist of a soft metal, preferably copper.

Further advantages and advantageous configurations of the subject matter of the invention can be found in the description, the claims and the drawing.

drawing The drawing shows several exemplary embodiments of the device according to the invention for supplying an internal combustion engine. It shows

FIG. 1 shows a longitudinal section through a fuel injection valve,

FIG. 2 shows an enlargement of FIG. 1 in the area designated II,

3 shows the same detail as FIG. 2 of a further exemplary embodiment,

FIG. 4 shows an enlargement of FIG. 3 in the area designated IV,

5 shows the same detail as FIG. 4 of a further exemplary embodiment and

Figure 6 shows the same detail as Figure 5 of another embodiment.

Description of the embodiments

1 shows a longitudinal section through a fuel injection valve for an internal combustion engine. The fuel injection valve has a housing 1 which comprises a first body which is designed as a valve holding body 3 and a second body which is designed as a valve body 5. The valve holding body 3 and the valve body 5 lie against one another on a contact surface 20 and are pressed against one another by a tensioning device, not shown in the drawing. A bore 12 is formed in the valve body 5, in which a piston-shaped valve needle 16 is arranged to be longitudinally displaceable. At its end on the combustion chamber side, the bore 12 is closed except for at least one injection opening 14, which connects the bore 12 with the combustion chamber of the internal combustion engine. In a section facing away from the combustion chamber, the valve needle 16 is sealingly guided its length in the bore 12 and controls the opening of the at least one injection opening 14 by its longitudinal movement in the bore 12 A pressure chamber 11 is formed in the bore 12 in the valve body 5, into which a high-pressure channel 10 runs in the valve body 5 and in the valve holding body 3, which connects the pressure chamber 11 to a high-pressure fuel source, not shown in the drawing. The high-pressure channel 10 passes through the contact surface 20 of the valve holding body 3 and valve body 5. Through the high-pressure channel 10, the pressure chamber 11 can be filled with fuel under high pressure, which then flows from the pressure chamber 11 past the valve needle 16 to the injection openings 14.

A leak oil chamber 7 is formed in the valve holding body 3 and is designed as a longitudinal bore in the center of the valve holding body 3. The leakage oil chamber 7 is essentially rotationally symmetrical and has a longitudinal axis 9 that is parallel to the longitudinal axis of the bore 12. The leak oil chamber 7 is connected to a leak oil system via a line (not shown in the drawing), so that there is always a low pressure in the leak oil chamber 7. The leakage oil chamber 7 is connected by the annular gap remaining between the valve needle 16 and the wall of the bore 12 to the bore 12 formed in the valve body 5, the annular gap only permitting a strongly throttled flow of fuel from the pressure chamber 11 into the leakage oil chamber 7. This is essential for the function, since there is at least occasionally a very high fuel pressure in the high-pressure channel 10, which can be over 100 MPa.

FIG. 2 shows an enlargement of the section from FIG. 1, designated II, in the region of the passage of the high-pressure duct 10 through the contact surface 20. In the exemplary embodiment shown here, a radial extension 27 is formed in the high-pressure channel 10, which extends with a part of its length in the valve holding body 3 and with a part of its length in the valve body 5. A sealing element 25 is arranged in the radial extension 27, which is linden-shaped and rests with its outer surface on the radial extension 27. A chamfer in the valve holding body 3 on the radial extension 27 forms an annular space 30 which is connected to the leakage oil space 7 via a connecting channel 32. As a result, the annular gap 29, which is formed between the outer circumferential surface of the sealing element 25 and the wall of the radial extension 27, is always connected to the leakage oil chamber 7 and is therefore depressurized. The sealing element 25 here consists of an elastic material, preferably of a plastic, and of the group of plastics, preferably of an elastic. Due to the fuel pressure in the high-pressure duct 10, the sealing element 20 is pressed radially outward, since in the annular gap 29 through the annular space 30 and its connection with the leakage oil space 7 there is a significantly lower pressure than in the high-pressure duct 10. This is counteracted by the radial expansion of the sealing element 25 the wall of the radial extension 27 is pressed and seals the high-pressure channel 10 against the gap remaining on the contact surface 20 between the valve body 5 and the valve holding body 3. As a result, no fuel can escape from the high-pressure channel 10 in an uncontrolled manner.

FIG. 3 shows a further exemplary embodiment of the sealing element 25, the section of FIG. 1 shown here being the same as that of FIG. 2. For further clarification, FIG. 4 shows a further enlargement of FIG. 3 in the section designated IV. A radial extension 27 is again provided in the valve holding body 3 in the high-pressure channel 10, but ends at the transition to the valve body 5. The diameter of the high-pressure channel 10 in the valve body 5 is significantly smaller than the diameter of the radial extension 27, so that an annular shoulder 35 is formed at the transition from the valve body 3 to the valve body 5. The sealing element 25 is rotationally symmetrical and has an L-shaped longitudinal section. This is on the sealing element 25 an annular disk-shaped contact surface 37 is formed, which comes to rest on the ring shoulder 35. Due to the pressure in the high-pressure duct 10, the elastic element 25 is pressed in the radial direction against the wall of the radial extension 27 and also through the L-shaped longitudinal section with the contact surface 37 against the ring shoulder 35. At the end of the radial extension 27 facing the valve body 5 a chamfer and thereby an annular space 30 is also formed, which is connected to the leakage oil space 7 via a connecting channel 32.

Figure 5 shows the same section as Figure 4 of another embodiment. Here, in turn, a radial extension 27 is provided in the valve holding body 3, which is delimited by a first annular surface 40 and a second annular surface 42, the second annular surface 42 being formed on the valve body 5. The first ring surface 40 is perpendicular to the wall of the radial extension 27, so that there is a rectangular longitudinal section of the radial extension 27. The sealing element 25 has a C-shape in longitudinal section, so that a first ring-shaped sealing surface 44 and a second ring-shaped sealing surface 46 are formed on the sealing element 25, the first sealing surface 44 on the first ring surface 40 and the second sealing surface 46 on the second ring surface 42 come to the plant. Due to the pressure in the high-pressure duct 10, the elastic element 25 is inflated and its outer lateral surface is pressed in the radial direction against the wall of the radial extension. In the same way as in the exemplary embodiment shown in FIG. 4, the sealing surfaces 44 and 46 are pressed against the corresponding ring surfaces 40 and 42, so that an all-round tight connection of the sealing element 25 with the radial extension 27 is produced. Here too, a chamfer and an annular space 30 formed thereby are provided in the valve holding body 3, which is connected via a connecting channel 32 and the leak oil chamber 7. A further exemplary embodiment is shown in FIG. 6, FIG. 6 showing the same detail as FIG. 5. The radial extension 27 is here essentially the same as the one shown in FIG. 5, but the sealing element 25 has a toroidal shape with a wall and a cavity 48 which is annular. The cavity 48 is connected to the high-pressure duct 10 via openings 50 which are formed in the wall of the toroidal sealing element 25. As a result, fuel can penetrate from the high-pressure channel 10 through the openings 50 into the cavity 48 of the sealing element 25 and inflate it. In this way, an all-round tight connection of the sealing element 25 with the limits of the radial extension 27 is achieved. It can also be provided here that an annular space is formed in the valve holding body 3 by a chamfer, which is connected to the leakage oil space 7 via a connecting channel and ensures that the annular space between the wall of the radial extension 27 and the sealing element 25 remains unpressurized.

In addition to the formation of the seal on a fuel injection valve, it can also be provided that such a seal of a high-pressure channel can also be formed in other devices, for example in high-pressure fuel pumps, low-pressure fuel pumps, valves or other supply devices for internal combustion engines. Furthermore, it can be provided that the fuel, but rather another fluid, for example water or a liquid gas, is passed through the high-pressure channel 10, that is to say any medium which can only transmit pressure forces. In addition to the materials for the sealing element 25 already mentioned, such as plastic and here in particular the elastomers, it can be provided, particularly at high pressures in the high-pressure duct 10, that the sealing element 25 be made of metal, for example made of copper, steel or another elastically deformable metal.

Claims

claims

1. Fuel injection valve for internal combustion engines with a housing (1) which comprises a first body (3) and a second body (5) on a contact surface

(20) abut each other and in which a high-pressure channel (10) is formed, which passes through the contact surface (20) of the two bodies (3; 5) and which is filled with a fuel which is at least temporarily under high pressure, characterized that in the high pressure channel (10) in the area of the contact surface (20) there is a sealing element (25) which is elastically deformable and is pressed by the pressure of the fuel in the high pressure channel (10) against the wall of the high pressure channel (10), whereby the High pressure duct (10) is sealed at the passage through the contact surface (20).

2. Fuel injection valve according to claim 1, characterized in that the elastic sealing element (25) is designed as a hollow cylinder and rests on the wall of the high-pressure channel (10) with its outer surface, one end of the elastic sealing element (25) in the first body (3) and the other end is arranged in the second body (5).

3. Fuel injection valve according to claim 1, characterized in that a radial extension (27) is formed in the high-pressure channel (10), in which the hollow cylindrical elastic sealing element (25) is arranged.

4. Fuel injection valve according to claim 3, characterized in that the radial extension (27) of one first annular surface (40) and a second annular surface (42) is limited, the first annular surface (40) being arranged in the first body (3) and the second annular surface (42) in the second body (5), and with two on the elastic sealing element (25) formed contact surfaces (44; 46), which are pressed against the ring surfaces (40; 42) by the pressure in the high-pressure channel (10).

5. The fuel injection valve according to claim 3, characterized in that the elastic sealing element (25) is designed in a toroidal shape, so that a cavity (48) is formed, the cavity (48) through openings (50) with the high-pressure channel (10). connected is.

6. The fuel injection valve according to claim 1, characterized in that an annular gap (29) present between the wall of the high-pressure duct (10) and the elastic sealing element (25) via a connecting duct (32) formed in the housing (1) and having a fuel-filled leak oil chamber (7 ) is connected, which is present in one of the two bodies (3; 5) and in which there is always a low pressure.

7. Fuel injection valve according to claim 6, characterized in that between the outer surface of the elastic sealing element (25) and the wall of the high-pressure channel (10) an annular space (30) is formed, into which the connecting channel (32) opens.

8. Fuel injection valve according to claim 1, characterized in that at the transition of the first body (3) to the second body (5) in the high-pressure channel (10) an annular shoulder (35) is formed, on which the elastic sealing element (25) with a contact surface ( 37) is present.

9. Fuel injection valve according to claim 8, characterized in that the elastic sealing element (25) is rotationally symmetrical and has an at least approximately L-shaped longitudinal section, the contact surface (37) being formed on the short leg of the L-shaped longitudinal section.

10. Fuel injection valve according to one of claims 1 to 9, characterized in that the elastic sealing element (25) consists of a plastic, preferably an elastomer.

11. Fuel injection valve according to one of claims 1 to 9, characterized in that the elastic sealing element (25) consists of an elastically deformable metal.

12. Fuel injector according to claim 11, characterized in that the metal is stainless steel.