WO2012171890A1

WO2012171890A1 - Fuel pump

Info

Publication number: WO2012171890A1
Application number: PCT/EP2012/061062
Authority: WO
Inventors: Rainer Schambeck; Hermann HÄMMERL; Bernd WÖLLISCH; Matthias Bleeck; Franz-Xaver Wagner; Steffen Kernbach
Original assignee: Continental Automotive Gmbh
Priority date: 2011-06-15
Filing date: 2012-06-12
Publication date: 2012-12-20
Also published as: DE102011077577B4; DE102011077577A1

Abstract

A fuel pump (4), in particular for fuel direct injection systems of motor vehicles, comprises a pump housing (1) and a low-pressure-side inlet valve (18) which is mounted on the pump housing (1). Said inlet valve comprises a movable closure body (21), an actuating element (27) for the closure body (21), and a valve seat device (219) with at least one passage opening (20) through which the actuating element (27) can act on the closure body (21) and with at least one further passage opening (20) through which a flow of fuel from an inlet duct (17) of the fuel pump (4) into a working chamber (14) of the fuel pump (4) is permitted when the inlet valve (18) is open, wherein the valve seat device (219) is welded to the housing (1). The welded connection is arranged such that fuel does not flow around it during the operation of the fuel pump (4).

Description

description

Fuel pump The invention relates to a fuel pump (4).

Fuel pumps are used in particular to promote

Fuel for storage injection systems used for internal combustion engines of motor vehicles. Accumulator injection systems for internal combustion engines of motor vehicles, such as in

Common rail systems should be able to provide the necessary volume flow and the required fluid pressure. The

High-pressure pump is to be adapted to a quantity of fuel to be supplied to consumption of the internal combustion engine at a corresponding load working point.

A generic fuel pump is known for example from the European patent application EP 2 236 809 A2. The fuel pump shown there has, in particular, an inlet valve which is firmly connected to the housing of the fuel pump. In order to allow the strongest possible connection to the pump housing, the connection is made by welding the inlet valve to the housing. Since the inlet valve forms a unit and is used as such in the housing of the fuel pump and is welded in the housing union difficult to ^¬ union, a secure connection by welding manufacturing technology, however, is very difficult to accomplish. Also, internal welds can lead to contamination of the fuel, which can subsequently cause failures of the pump or the downstream storage unit (rail) or the injectors in the engine block.

Object of the present invention is therefore a

Provide fuel pump that is relatively easier to manufacture and their probability of failure during the operating time of a motor vehicle is as low as possible. This object is achieved by the fuel pump with the features according to claim 1.

The fuel pump according to the invention is particularly ^¬ sets of fuel direct injection systems in motor vehicles. It has a pump housing and a low-pressure side inlet valve that is attached ^¬ placed on the pump housing. This fuel pump comprises a movable closure ^¬ body, an actuator for this closure body and a valve seat device. The valve seat device includes at least one passage opening through which the Actuate the ^¬ supply element, such as a plunger which reciprocates by an actuator and is movable, can act on the closure body. Furthermore, the valve seat device has at least one further through opening, preferably a plurality, through which, when the inlet valve is open, fuel flow from an inlet channel of the fuel pump into a working space of the fuel pump is made possible.

The closure body can in particular be formed as a spring plate ^¬ that on the side remote from the ram side of the valve plate rests in the closed inlet valve on the valve plate and thereby at least closes a further passage opening, so that no fuel may flow through the valve seat ^¬ device, and is spaced by the plunger of the valve seat device with the inlet valve open, so that the fuel flow through the valve seat device is made possible.

The valve seat assembly is welded to the housing. According to the invention, however, the welded connection is arranged so that it is not surrounded by fuel during operation of the fuel pump. As a result, for example, unclean welds are not permanently exposed to the aggressive fuel environment; In particular, they are not used in the operation of the vehicle by fuel such as gasoline or diesel lapped. Since such improperly executed welds, in particular spatter, which in particular arise when welded in relatively inaccessible places, usually do not adhere permanently, particles can solve during operation of the motor vehicle and thereby possibly to failure of the fuel pump and the subsequent fuel-carrying Parts of an engine, especially the injectors lead.

In an advantageous embodiment, the valve seat device has two sections:

On the one hand this is a valve seat portion which includes the through hole ^¬ (s) and an attachment portion. This extends from the valve seat portion through a wall bounding the inlet channel of the housing of the fuel pump ^¬ out towards the outside of the housing. On the external side of the housing, preferably at the Au ^¬ ßenseite of the housing which faces the outer side end portion of the fixing portion is welded to the housing. This has the advantage that the weld is easier to access from the outside compared to a deeper in the housing of the fuel pump lying weld. The accessibility for a welding device, for example a laser welding device, as well as for the protective gas required for welding is greatly facilitated in the region of the outside of the housing. This simplifies the manufacturing process as a whole and therefore reduces the manufacturing costs. In addition, the easy accessibility of the weld leads to a better execution of the welds. In particular, spatters and the like can be largely avoided. Thereby, the connection of the inlet valve to the housing of the high-pressure pump is less susceptible to material fatigue or even a fracture of the weld, which also contributes to a reduction in the failure probability of the fuel pump over the entire operating time in the motor vehicle.

In an advantageous embodiment, the valve seat portion and the attachment portion can be integrally formed be. This allows the manufacture of a valve seat device in one piece, for example as a turned part.

In a particularly preferred embodiment of the VEN are tilsitzabschnitt and, however, the fixing portion formed ^¬ two pieces. In this way, the valve seat portion and the attachment portion can be made of different materials. Therefore, for example, its mountings ^¬ supply section of a better weldable material can be made with relatively less carbon content and therefore can lead to a high-quality product with a longer life span.

At the same time, the valve seat portion may be made of comparatively high carbon material. Although such materials have a relatively greater hardness, which in particular against Materialermüdungserschei ^¬ calculations by the permanent interaction with an actuator of the inlet valve, in particular a plunger, may be beneficial.

Advantageously, the attachment portion, in ^¬ example, a spacer sleeve or a spacer ring, which is welded at one end in the region of the outside of the housing to the housing, at its opposite end with the

Valve plate form-fitting together. As a result, a movement of the valve seat portion in the direction of the inlet channel 17 is counteracted under the action of force by the fuel pressure in the working chamber of the fuel pump. Furthermore, advantageously additionally cooperate with the housing by a force-locking connection, the valve seat portion which can be formed for example as a valve ^¬ plate, so that the valve seat portion from two directions is securely held.

Embodiments of the invention are explained below with reference to the schematic drawings. Show it:

FIG. 1 shows a schematic cross-sectional view of a fuel pump known from the prior art,

FIG. 2 shows a schematic cross-sectional representation of the connection region of the inlet valve and the housing of the fuel pump according to the prior art,

FIG. 3 shows a schematic cross-sectional view of the fuel pump according to the invention,

FIG. 4 is a schematic cross-sectional view of the article of FIG. 3.

Figure 1 shows a fuel pump 4 according to the prior art, disclosed in the European patent application EP 2 236 809 A2. The fuel pump 4 comprises a pump body 12 having a longitudinal axis 13 and a working space 14. A pump piston 15 is disposed in the working chamber 14 and reciprocates along the longitudinal axis 13, wherein it cyclically causes a change in the volume of the pump chamber 14. A lower part of the piston is connected on the one hand with a spring 16 which moves the pump piston 15 in the direction of a maximum working chamber volume, and on the other hand with a camshaft, not shown, which is rotated by a drive shaft of the motor and cyclically moves the piston upward, whereby the Spring 16 is compressed. An inlet channel 17 extends from a side wall of the working chamber 14 and is connected to a low-pressure inlet, not shown, which is fed by a low-pressure pump, not shown. The inlet valve 18 has a disk 19 as a valve seat device, with a plurality of through holes designed as holes, through which the fuel can flow when the valve is open; and a ver ^¬ moldable circular spring plate 21 which rests on the Ar ^¬ Chamber of Labor 14 facing side of the disk 19th With closed inlet valve 18, the spring plate closes the passage openings 20. The inlet valve 18 is ei ^¬ nerseits controlled by the pressure difference between the inlet channel 17 and working space 14 of the fuel pump 4, which is why this ge ^¬ closed or without any action on the intake valve 18, when the fuel pressure in the working space 14 is higher than the fuel pressure in the inlet channel 17. Similarly, the intake valve is open when the fuel pressure in the working space 14 is lower than the fuel pressure in the intake passage 17.

In addition to a hydraulic control, an electrical control of the inlet valve 18 is possible: The inlet valve 18 has a plunger 27, which is contacted with the spring plate through a passage opening 20 of the disc 19. Plunger 27 can be moved by driving the electromagnet 30 through the armature 31 in the direction of the inlet channel 17, against the spring 29 caused by the biasing direction in the direction of the working space 14. Without the action of the electromagnet 30 pushes the plunger by the spring force of the spring 29 on the Spring plate 21. If the fuel pressure in the working chamber 24 is correspondingly low, the inlet valve 18 is opened. Will the

Energized electromagnet 30, the armature 31 pulls back the plunger 27 and the spring plate closes - with a corresponding hydrau ^¬ lischer pressure difference - the through holes of the disc 19: the inlet valve 18 is closed.

Highlighted by a circle 50 of the connecting portion between the intake valve 18 and the housing 1 of the intake ^¬ valve 18 is possible to see weld 51, which connects the plate 19 with the in the housing 1, so that by the action of force by the fluid pressure of the chamber 14, the Disc 19 is not moved.

Figure 2 shows a slightly modified embodiment of an intake valve 18, the fuel pump, however, is constructed the same overall as the fuel pump 4 of Figure 1. In particular, the essential components are the same and also provided with the same reference numerals. Likewise, the connection of Disk 19 accomplished with the housing 1 of the fuel pump 4 via a weld 51, wherein here, too, the weld 51 is surrounded by fuel through the fuel passage 43. As already described, the internal point of the weld with the usual welding process is difficult to access, which is why the weld 51 may possibly have shortcomings over the period of use of the fuel pump 4, in particular welding spatter. Such splashes of sweat can come loose and subsequently lead to damage to the pump and / or the subsequently fuel-carrying hydraulic ^{parts, in} particular the injectors.

FIG. 3 basically shows the same inlet valve as that shown in FIG. However, the disc 19 is held by force ^¬ conclusively by the spacer ring, not with the housing

1, whereby a movement in the direction of the inlet channel 17 is prevented, in particular by the action of a force by fuel under high pressure working chamber 14. The spacer ring 2 is guided from its positive connection with the disc 19 to the outer wall of the housing 1. There he is over one

Weld 53 welded to the outer wall of the housing 1. The weld is therefore now not in hydraulic communication with the inlet channel 17, which is why in relation to FIG

2 mentioned disadvantages, for example by detachment from the weld, do not exist here. Furthermore, in the production of the high-pressure pump 4 before fitting the middle part of the inlet valve 18, the spacer ring 2 can be welded to the housing 1 with very little technical effort.

A comparison of Figures 2 and 3 shows that the further welded connection 52 of the housing middle part of the inlet ^¬ valve 18 now takes place in the embodiment according to the invention with the spacer ring 2 and not, as in the figure 2, directly to the housing. However, as can be seen in FIG. 3, the sleeve 54 of the middle part of the inlet valve 18 projects into the inlet channel 17, over the weld 52. In front- geous enough, there is here also adhesion between the spacer ring 2 and the sleeve 54, a direct flushing with fuel, which could also be detrimental for For why is ^¬ close.

In addition to the non-positive connection of the sleeve 54 to the spacer ring 2, the spacer ring 2 is also non-positively connected to the housing 1. In addition to the positive retention by the spacer ring 2 further consists of a non-positive connection of the disc 19 with the housing. 1

Also seen in the comparison of Figures 2 and 3, for the insertion of the spacer ring 2 between sleeve 54 and housing 1, a step in the sleeve 54 has been lowered from a previous step height Di to a current step height D2 (Figure 3).

FIG. 4 shows a cross-sectional view of the arrangement according to FIG. 3 along the section axis J-J. You can see two

Connecting channels 43 and a taper of the inner diameter of the spacer ring 2 in the form of an inclined step. The stage begins in something at the level of the connecting channels 43. On the ent ^¬ opposing outer side of the ring begins in the region of the onset of the inclined step, a notch 55 which extends up to the disc 19. Such a paragraph on Distanzringaußendurchmesser serves to avoid a line contact between the spacer ring 2 and disc 19 under the influence of high pressure in the Arbeitskämmer.

Through this recess, the rigidity of the spacer ring 2 is reduced. To counteract this, the wall was strengthened in this area from the stage to the disc 2, as just described.

Claims

claims

1. Fuel pump (4), in particular for direct fuel injection ^¬ fuel injection systems of motor vehicles with:

a pump housing (1),

a low-pressure side inlet valve (18) attached to the pump housing (1), comprising:

a movable closure body (21),

- An actuating element (27) for the closure body (21),

a valve seat device (219)

- With at least one through hole (20) through which the actuating element (27) can act on the Ver ^¬ closing body (21),

- With at least one further passage opening

(20) through which fuel flow from an inlet channel (17) of the fuel pump (4) into a working space of the inlet valve (18) when the inlet valve (18) is open

Fuel pump (4) is enabled

the valve seat device (219) being welded to the housing (1), characterized in that

the welded connection is arranged so that it is not surrounded by fuel during operation of the fuel pump (4).

2. Fuel pump (4) according to claim 1, characterized in that the valve seat device (219) comprises:

- A valve seat portion (19) having the passage openings (20) and

a fastening section (2), which is guided by an inlet channel (17) delimiting wall of the housing (2) to an outer side of the housing (2), wherein the welding ^¬ connection on one of the outside of the housing (2) facing side of the Attachment section (2) is arranged.

3. Fuel pump (4) according to claim 2, characterized in that the valve seat portion (19) and attachment portion (2) are integrally formed.

4. Fuel pump (4) according to claim 2, characterized in that valve seat portion (19) and fastening portion (2) is formed in two parts, wherein the fastening portion (2) is designed as a spacer sleeve.

5. Fuel pump (4) according to one of claims 2 to 4, wherein the attachment portion (2) at its the working chamber (14) facing the end has a notch (55) on its outside, extending along the mounting portion (2) to extends to the disc 19.

6. Fuel pump (4) according to claim 5, wherein the notch (55) is circumferentially around the outer diameter of the end portion of the mounting portion (2).