High-pressure fuel pump

Abstract

A high-pressure fuel pump for a fuel injection system of an internal combustion engine includes a pump housing and at least one fastening flange that is fixed to the pump housing by a welding. The welding has one weld region and at least one weld bead arranged laterally from the weld region. The weld bead is arranged in a receiving space formed between the pump housing and the fastening flange.

Claims

1. A high-pressure fuel pump for a fuel injection system of an internal combustion engine, comprising: a pump housing; and at least one fixing flange that is fixed to the pump housing by a welded joint, the welded joint including a weld region and at least one weld bead arranged laterally with respect to the weld region, wherein the weld bead is arranged in a receiving space formed between the pump housing and the fixing flange by a circumferential groove in one of the pump housing and the fixing flange, and wherein an opening connects the receiving space to an environment.

2. The high-pressure fuel pump as claimed in claim 1, wherein the welded joint is formed via capacitor discharge welding.

3. The high-pressure fuel pump as claimed in claim 1, wherein the receiving space is wider than the weld bead when viewed in a radial direction.

4. The high-pressure fuel pump as claimed in claim 1, wherein the receiving space is an annular space.

5. The high-pressure fuel pump as claimed in claim 1, wherein the pump housing includes a relief cut that is arranged within the receiving space and has a smaller diameter than a contact section of the pump housing, and wherein the contact section makes contact with the fixing flange.

6. The high-pressure fuel pump as claimed in claim 5, wherein the contact between the contact section and the fixing flange is a press fit.

7. The high-pressure fuel pump as claimed in claim 1, wherein the environment is external to the pump housing.

8. The high-pressure fuel pump as claimed in claim 1, wherein the fixing flange is configured to be fixed directly to the internal combustion engine.

9. The high-pressure fuel pump as claimed in claim 1, wherein the pump housing partially encircles the receiving space to define the circumferential groove such that the receiving space is bounded longitudinally above and below by the pump housing.

10. The high-pressure fuel pump as claimed in claim 1, wherein the receiving space has a first circumferential gap between the pump housing and the fixing flange, the opening has a second circumferential gap between the pump housing and the fixing flange, and the first circumferential gap is larger than the second circumferential gap.

11. The high-pressure fuel pump as claimed in claim 1, wherein the pump housing has a longitudinal axis, and wherein the circumferential groove is recessed in the one of the pump housing and the fixing flange laterally with respect to the longitudinal axis.

12. The high-pressure fuel pump as claimed in claim 11, wherein the circumferential groove is recessed laterally inwardly in a lateral surface of the pump housing.

13. The high-pressure fuel pump as claimed in claim 11, wherein the circumferential groove is recessed laterally outwardly in a lateral surface of the fixing flange.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Embodiments of the disclosure are explained below with reference to the attached drawing. In the drawing:

(2) FIG. 1 shows a longitudinal section through a first embodiment of a high-pressure fuel pump having a pump housing, a fixing flange and a weld region;

(3) FIG. 2 shows an enlarged detail of the weld region from FIG. 1;

(4) FIG. 3 shows an illustration similar to FIG. 2 of a second embodiment; and

(5) FIG. 4 shows an illustration similar to FIG. 2 of a third embodiment.

(6) Elements and regions which have equivalent functions in the following figures bear the same reference signs.

DETAILED DESCRIPTION

(7) In FIG. 1, a high-pressure fuel pump for an internal combustion engine (not shown specifically) bears the reference sign 10 overall. The high-pressure fuel pump 10 has a pump housing 12 which is substantially cylindrical overall and in or on which the essential components of the high-pressure fuel pump 10 are arranged. Thus, the high-pressure fuel pump 10 has an inlet/quantity control valve 14, a delivery plunger 18, which is arranged in a delivery chamber 16 and to which a reciprocating motion can be imparted by a drive shaft (not shown), an outlet valve 20 and a pressure relief valve 22.

(8) In the housing 12, there is a first passage 24, which extends coaxially with the delivery chamber 16 and with the delivery plunger 18 and which leads from the delivery chamber 16 to a second passage 26, which is arranged at an angle of 90 to the first passage 24 and in which the pressure relief valve 22 is accommodated. In FIG. 1, a longitudinal axis of the pump housing 12 bears the reference sign 28 overall. At the top in FIG. 1, a pressure damper 30 is arranged in the pump housing 12.

(9) In operation, fuel is drawn into the delivery chamber 16 by the delivery plunger 18 via the inlet and quantity control valve 14 during a suction stroke. During a delivery stroke, the fuel in the delivery chamber 16 is compressed and expelled via the outlet valve 20 into a high-pressure region (without a reference sign), for example, to a common fuel line (rail), for example, where the fuel is stored under high pressure. Here, the fuel quantity expelled during a delivery stroke is set by means of the electromagnetically actuated inlet and quantity control valve 14. If there is an impermissible excess pressure in the high-pressure region, the pressure relief valve 22 opens, thereby enabling fuel to flow out of the high-pressure region into the delivery chamber 16.

(10) The high-pressure fuel pump 10 is a plug-in pump, which can be inserted into a corresponding opening in a cylinder head of the internal combustion engine. A circumferential and annular fixing flange 32 is fixed to the pump housing 12 and, by means of said flange, the high-pressure fuel pump 10 can be fixed, e.g. screwed, to the cylinder head. As can be seen in detail from FIG. 2, the fixing flange 32 is fixed to the pump housing 12 by a welded joint 34, which comprises a weld region 36 and two weld beads 38 and 40 arranged laterally with respect to the weld region 36. The welded joint 34 is produced by means of capacitor discharge welding.

(11) A length L1 of the weld region 36 is produced by an overlap between a radially outer contact section 42 on the pump housing 12 and a radially inner contact section 44 on the fixing flange 32, said contact section having a length or height L2. In the present case, the contact sections 42 and 44 make contact with each other with a press fit. In the embodiment illustrated in FIGS. 1 and 2, a receiving space 46 designed as an annular space, which is formed by a circumferential groove 47 in an outer wall of the pump housing 12, is present on the outside of the pump housing 12, directly below the weld region 36.

(12) The weld bead 40 at the bottom in FIG. 2 is arranged in the receiving space 46. In this case, the receiving space 46 is wider than the weld bead 40 when viewed in the radial direction. In FIG. 2, an extent B1 of the receiving space 46 is therefore greater than an extent B2 of the weld bead 40. Similarly, the receiving space 46 is also higher than the weld bead 40 in the axial direction, i.e. parallel to the longitudinal axis 28. For reasons of clarity, however, the corresponding extents are not shown in FIG. 2 and are not provided with reference signs.

(13) The size ratios of the receiving space 46 relative to the lower weld bead 40 ensure that a free surface of the weld bead 40, which in the present case has the idealized shape of a quarter circle in cross section, is not in contact with the radially outer circumferential wall of the pump housing 12. As can be seen from FIG. 2, there is a circumferential gap between a radially outer lateral surface 48 of the pump housing 12, the lateral surface being situated below the receiving space 46, and a radially inner lateral surface 50 of the fixing flange 32, said gap forming an opening 52, which connects the receiving space 46 to an environment 54.

(14) It can be seen from FIG. 2 that the diameter of the pump housing 12 is smaller in the region of the radially outer lateral surface 48 arranged below the receiving space 46 in the figure than in the region of contact section 42 arranged above the receiving space 46 in the figure. This makes it possible to use the fixing flange 32 of the pump housing 12 as a clamping diameter in the region of the radially outer lateral surface 48 during pre-mounting of the fixing flange 32 on the pump housing 12.

(15) FIG. 3 shows an alternative embodiment. In this embodiment, the receiving space 46 is formed not by a groove but simply by what is referred to as a plunge cut 56 in the pump housing 12, wherein the plunge cut 56 is arranged directly below contact section 42 in the figure.

(16) In the embodiment in FIG. 4, the receiving space 46 is formed by a plunge cut 58 in the fixing flange 32, wherein the plunge cut 58 is arranged directly below contact section 44 in the figure. In the embodiment shown in FIG. 4, there is furthermore additionally also a relief cut 60 in the pump housing 12 opposite the plunge cut 58 in the fixing flange 32, said relief cut 60 being at some distance from contact section 42, however, and having only a slightly smaller diameter than contact section 42.

(17) The relief cut 60 allows simple installation of the fixing flange 32 since the press-fitting of the fixing flange 32 onto the pump housing 12 takes place only in the region of contact section 42. In other respects, attention is drawn to the fact that it is possible, by means of a radial dimension B3, which indicates the depth of the plunge cut 58 in the fixing flange 32, to influence the elastic properties of the fixing flange 32 in this region. It is thereby possible to adjust the effect of the screwing of the fixing flange onto the cylinder head on the loading of the welded joint 34. The geometrical configuration of contact section 44 on the fixing flange 32 also offers such a means of influence.