WO2014086522A1 - High-pressure accumulator for a fuel injection system and method for the assembly of a high-pressure accumulator - Google Patents

Abstract

The invention relates to a high-pressure accumulator for a fuel injection system, in particular a common rail injection system, comprising an elongate accumulator body (1) with a longitudinal bore (2) from which multiple transverse bores (3) branch off, said transverse bores extending through high-pressure ports (4) arranged on the outer circumference of the accumulator body (1). According to the invention, a single-part or multi-part tubular insert (5) for realizing a reduction in volume is inserted into the longitudinal bore (2). The invention also relates to a method for the assembly of a high-pressure accumulator of said type.

Description

 description

title

 High-pressure accumulator for a fuel injection system and method for mounting a high-pressure accumulator

The invention relates to a high-pressure accumulator for a fuel injection system, in particular a common-rail injection system, with the features of the Oberbe-handle of claim 1. Furthermore, the invention relates to methods for mounting such a high-pressure accumulator.

State of the art

A high-pressure accumulator of the aforementioned type is apparent from the published patent application DE 10 2007034 720 A1. It has an elongated storage body with a lateral surface in which a number of high-pressure ports are formed, and a longitudinal bore defining a cavity, which forms interfaces with transverse bores of the high-pressure ports. The high-pressure connections serve to connect fuel! by means of which the fuel stored in the high-pressure accumulator and under high pressure can be injected into a combustion chamber of an internal combustion engine. A high pressure pump supplies the high pressure accumulator with high pressure fuel.

Based on the above-mentioned prior art, the present invention has for its object to provide a high-pressure accumulator for a fuel injection system with a reduced storage volume, the geometry of the storage body should remain as unchanged as possible. The reduced storage volume allows quick start release in an internal combustion engine with start-stop function. Because with a reduced storage volume, less fuel must be compressed by the upstream high pressure pump, so that the start release is faster. To solve the problem, a high-pressure accumulator with the features of claim 1 is proposed. Advantageous developments of the invention are specified in the subclaims. Furthermore, a method for assembling a high-pressure accumulator according to the invention is proposed.

Disclosure of the invention

The proposed high-pressure accumulator for a fuel injection system, in particular a common-rail injection system, comprises an elongate accumulator body with a longitudinal bore from which branch off a plurality of transverse bores, the high pressure connections arranged on the outer periphery of the accumulator body. According to the invention, it is provided that a single-part or multi-part tubular insert for volume reduction is inserted into the longitudinal bore. The one-piece or multi-piece tubular insert has a certain wall thickness, which defines over the length and the diameter of the insert a volume that is lost to the storage volume. That is, the storage volume of the storage body formed by the longitudinal bore and the transverse bores is reduced. As a result, a high-pressure pump upstream of the high-pressure accumulator must compress less fuel in order to enable start-up release in a start-stop function. This means that the start release is faster. When the storage volume is reduced by receiving an insert in the longitudinal bore of the storage body, the geometry of the storage body can furthermore remain unchanged. This means that already existing geometries can be used.

Although a reduction of the storage volume could also be achieved by reducing the diameter of the longitudinal bore of the storage body, this would mean an additional hedging effort to ensure the pulse stability of the storage body. By maintaining the bore diameter and the rest of the geometry of the storage body eliminates additional hedging. Preferably, the one- or multi-part tubular insert has at least one

Pipe section with an outer diameter D _A R smaller than the diameter this is the length of the longitudinal bore of the storage body, so that fuel can flow around the pipe section. This means that at least in sections between the insert and the storage body, an annular gap is formed, which is traversed by fuel during operation of the fuel injection system. At the same time, the tube shape of the insert ensures that fuel can flow through the insert.

Furthermore preferably, the one-part or multi-part tubular insert has at least one clamping section with an outer diameter D _A K which is greater than the diameter D | _{S is} the longitudinal bore of the storage body. About the clamping portion of the insert in the axial and / or radial direction is fixed in position. The radial excess of the clamping portion is chosen such that a press fit is achieved. This means that the tubular insert in the region of the clamping section bears against the inner wall surface of the storage body delimiting the longitudinal bore under radial prestressing. The press fit or the clamping action is designed such that in all operating states no axial displacement of the insert relative to the storage body takes place.

Preferably, the clamping portion is disposed at one end of the insert. Particularly preferably, in each case a clamping section is arranged at both ends of the tubular insert. The radial position of the insert within the longitudinal bore of the storage body is then defined via the clamping sections. At the same time the maintenance of an at least partially annular gap between the insert and the storage body is ensured. Alternatively or additionally, it is proposed that the clamping section has shell-side openings for the formation of at least one spring arm. With the arrangement of the clamping portion at one end of the insert, the formation of a spring arm can be done in a simple manner by longitudinal slots. The thus released spring arm can then be radially expanded to the outer diameter D _A K, for example by bending. The openings are preferably not only the formation of at least one spring arm, but at the same time as flow openings for the fuel, which flows around the insert at least partially outer peripheral side. Advantageously, the clamping section has two or more, preferably at least three, spring arms which are connected to one another at the same distance .beta. are orders. In this way, over the scope of the insert, a uniform clamping effect can be achieved when the spring arms are the same.

According to a preferred embodiment of the invention, a clamping portion is formed with at least one spring arm at both ends of the insert, wherein the spring arms are arranged angularly offset. By this measure, the positional fixation of the insert is further improved.

In a further development of the invention it is proposed that at least one

Spring arm for radial expansion to the outer diameter D _A K and to form a clamping surface at its free end is bent V-shaped. The V-shape results from a radially outwardly extending portion of the spring arm, followed by a radially inwardly extending portion connects, which also forms the end portion of the spring arm. The radially inwardly extending portion facilitates the insertion of the insert into the longitudinal bore of the storage body. Several V-shaped curved spring arms, which are arranged at the same angular distance from each other, form in this way a kind of insertion cone. The clamping surface is formed on the outside in the region of the intersection of the two sections.

Advantageously, the clamping portion is formed on a clamping part, which is non-positively, positively and / or materially connected to a pipe section forming the pipe section. The connection may for example have been produced by means of laser welding. The multi-part design of the insert allows a length adjustment, so that regardless of the respective length of the storage body and / or the number of cylinders of the internal combustion engine, the same components can be used in the assembly of a high-pressure accumulator according to the invention. All you have to do is cut the pipe section to length and connect it to the clamping part. Ideally, the insert is formed in three parts and comprises a pipe part and two clamping parts, which are connected after elongation of the pipe part with this.

Furthermore, it is proposed that the insert is radially elastically deformable at least in one section. If the clamping portion has at least one spring arm, this is radially elastically deformable. In addition, can However, another section, for example, the pipe section at least partially radially elastically deformable. This has the advantage that pressure pulsations within the longitudinal bore of the storage body can be minimized, whereby at the same time the injection accuracy of the system increases.

Furthermore, a method for assembling a high-pressure accumulator according to the invention is proposed. This is characterized in that for insertion and positioning of the insert in the longitudinal bore of the storage body, a mounting sleeve is pushed onto the clamping portion, the outer diameter D _A M smaller than the outer diameter D _A K of the clamping portion and smaller than the inner diameter D | _{S is} the longitudinal bore. After positioning the insert in the bearing bore, the mounting sleeve is removed again. The mounting sleeve presses the at least one spring arm of the clamping section radially inwards, so that the outer diameter D _A K generating the clamping effect is reduced. The mounting sleeve prevents the insertion of the insert in the longitudinal bore of the storage body to damage the longitudinal bore bounding inner wall surface of the storage body by the spring arm. A preferred embodiment of the invention will be explained in more detail with reference to the accompanying drawings. These show:

1 shows a side view of a high-pressure accumulator according to the invention, FIG. 2 shows a longitudinal section through the accumulator body of the high-pressure accumulator of FIG. 1,

3 shows a longitudinal section through the storage body of the high-pressure accumulator of FIG. 1 with insert,

4 shows two sectional views, which show the clamping sections of the insert of FIG. 3 in an enlarged view,

5 is a perspective view of a clamping portion of the insert of Fig. 3, 6 is a sectional view of the clamping portion of the insert of FIG. 3,

7 is a plan view of the clamping portion of Fig. 6,

Fig. 8 is a plan view of the insert of Fig. 3 and

Fig. 9 is a schematic representation of an assembly process with the aid of a mounting sleeve. Detailed description of the drawings

The high-pressure accumulator shown in FIG. 1 has an elongate accumulator body 1 with four high-pressure connections 4 arranged on the outer circumference for the connection of fuel! Njektoren (not shown) on. In addition, the storage body 1 further connections. The port 14 serves to connect a high-pressure pump (not shown), which supplies the high-pressure accumulator with high-pressure fuel. He is also arranged on the outer circumference side. Two further connections in the form of receptacles 15, 16 are each arranged on the front side and serve to receive a pressure sensor (not shown) and a pressure regulating valve (not shown). Another radially outgoing connection 17 serves to connect the high-pressure accumulator with a return (not shown). Furthermore, two fastening tabs 18 are arranged on the storage body 1. Fig. 2 shows the storage body 1 of the high-pressure accumulator of FIG. 1 in one

Longitudinal section. This can be seen that the storage body 1 has a longitudinal bore 2 and thereof transverse bores 3, which pass through the high pressure ports 4. All connections 14, 17 and receptacles 15, 16 are connected to the longitudinal bore 2 directly or indirectly via a transverse bore. For the sake of clarity, the storage body 1 is shown in FIG. 2 without insert 5. The longitudinal bore 2 in the present case has a diameter D | _S of 9 mm (see Fig. 4) and a length of 233.5 mm.

The storage body with insert 5 is shown in FIG. The insert 5 has a central tube section 6 whose length is adapted to the length of the longitudinal bore 2 of the storage body 1, and two end Klemmab- sections 7, each with three spring arms 9, which fix the insert 5 in the longitudinal bore 2. For the outer diameter D _A R of the pipe section 6 is smaller than the diameter D | 7 mm with 7 mm _{S of} the longitudinal bore 2 is selected (see Fig. 4), while the outer diameter D _A K of the clamping portions 7 each have a radial excess relative to the diameter D | _S own. Accordingly, the spring arms 9 bear against the inner wall surface of the storage body 1 with a radial prestress. The inner diameter D | _{In the present case, R} is 4 mm, so that a reduction of the storage volume of the storage body 1 of 6051 mm ^{2 is} achieved by the insert 5 over a length of 233.5 mm.

As also shown in FIG. 4, the spring arms 9 of a clamping portion 7 are released by slot-shaped openings 8. The perforations 8 are formed in the same width at the same angular distance from each other, so that the spring arms 9 are arranged at the same Wnkelabstand ß to each other and the same width b, in this case 2 mm, have (see Fig. 7). However, the spring arms 9 of the one clamping section 7 are offset by the angle γ, which corresponds to half a wnkelabstand ß, arranged offset to the spring arms 9 of the other clamping portion 7 (see Fig. 4 and Fig. 8).

The spring arms 9 have a length of 7 mm and are bent at their ends V-shaped, so that clamping surfaces 10 are formed, which are in the range of the outer diameter D _A K (see Fig. 4 and Fig. 5). The V-shape is formed by two Federarmabschnitten enclosing an angle α of 120 ° (see Fig. 6). The length l ₃ and l _{4 of} the two V-shaped bent Federarmabschnitte is 1.65 mm, respectively. This is followed by a spring arm section with a length l ₂ of 3.7 mm, which is not bent. The strength s of the spring arms 9 is presently 1 mm.

In addition to the illustrated one-piece design of an insert 5, the insert 5 can also be designed to be constructed. In this case, the insert 5 comprises a tube part 12, which is connected to two clamping parts (11) (see Fig. 4, reference numerals in parentheses). The connection may have been made by laser welding after the tube part 12 has been cut to the correct length. It can be seen from FIG. 9 how the insert 5 is ideally inserted into the longitudinal bore 2 of the storage body 1. For this purpose, a mounting sleeve 13th taken to the aid, which is pushed onto the clamping portion 7 of the insert 5. The mounting sleeve 13 has an outer diameter D _A M, which is smaller than the outer diameter D _A K of the clamping portion 7 and smaller than the diameter D | _{S of} the longitudinal bore 2 of the storage body 1 is. The spring arms 9 of the clamping section 7 are pushed radially inwards when the mounting sleeve 13 is pushed on, so that the insert 5 can be inserted into the latter without damaging the inner wall surface of the storage body 1.

Claims

claims 1. High-pressure accumulator for a fuel injection system, in particular a  Common rail injection system, comprising an elongated storage body (1) with a longitudinal bore (2), branch off from the plurality of transverse bores (3), the outside circumference of the storage body (1) arranged high-pressure connections (4),  characterized in that in the longitudinal bore (2) is a single or multi-part tubular insert (5) is used to reduce the volume. 2. High-pressure accumulator according to claim 1, characterized in that the one- or multi-part tubular insert (5) has at least one pipe section (6) with an outer diameter (DAR) which is smaller than the diameter (D | _S ) of the longitudinal bore (2) of the storage body (1), so that the pipe section (6) can be flowed around by fuel. 3. High-pressure accumulator according to claim 1 or 2, characterized in that the one- or multi-part tubular insert (5) has at least one clamping section (7) with an outer diameter (D _A K) which is greater than the diameter (D | _S ) of the longitudinal bore (2) of the storage body (1) is, so that the insert (5) via the clamping portion (7) is fixed in position in the axial and / or radial direction. 4. High-pressure accumulator according to claim 3, characterized in that the clamping portion (7) at one end of the insert (5) is arranged and / or shell-side openings (8) for forming at least one spring arm (9) has. High-pressure accumulator according to claim 4,  characterized in that the clamping portion (7) has two or more, preferably at least three, spring arms (9) which are arranged at the same angular distance (ß) to each other. High-pressure accumulator according to claim 4 or 5,  characterized in that at both ends of the insert (5) each have a clamping portion (7) with at least one spring arm (9) is formed, wherein the spring arms (9) are arranged angularly offset. High-pressure accumulator according to one of claims 4 to 6, characterized in that at least one spring arm (9) for radial expansion to the outer diameter (D _A K) and for forming a clamping surface (10) at its free end is bent V-shaped. High-pressure accumulator according to one of claims 3 to 7,  characterized in that the clamping portion (7) on a clamping part (1 1) is formed, which with a pipe section (6) forming tube part (12) non-positively, positively and / or materially, preferably by laser welding, is connected. High-pressure accumulator according to one of the preceding claims,  characterized in that the insert (5) is radially elastically deformable at least in one section. 0. A method for assembling a high-pressure accumulator according to one of claims 3 to 9, characterized in that for insertion and positioning of the insert (5) in the longitudinal bore (2) of the storage body (1) a mounting sleeve (13) on the clamping portion (7) is pushed, the outer diameter (DAM) smaller than the outer diameter (D _A K) of the clamping portion (7) and smaller than the inner diameter (D | _S ) of the longitudinal bore (2), and the mounting sleeve (13) after positioning of the insert (5) in the bearing bore (2) is removed.