EP1429028A2 - Device for delivering a fluid, particularly fuel pump - Google Patents

Abstract

Fuel delivery elements (44a) each supply a first fluid onto one side of certain wall sections (WS) (64a-c) that move and are assigned to them. The other side of the WS has an inlet and outlet for a second fluid. One WS has a flexible metal membrane (FMM) that has an inactive position, into which the FMM returns when impinged by a spring device if equal pressure prevails on both sides of the FMM.

Description

State of the art

The invention relates to a device for conveying a Fluids, in particular a fuel pump, with at least two cyclically operating conveyor elements, one first fluid on each side of a movable Promote wall section associated with a conveyor element and its other side with an inlet and a Outlet for a second fluid is connected.

Such a device is known from EP 1 101 940 A2 known. This shows an axial piston fuel pump, which has two delivery pistons. One for each The work area assigned to the delivery piston is fluid with the connected to one side of a rubber membrane. The other side the rubber membrane is connected to an inlet valve with a Fluid inlet and an outlet valve with a Fluid drain connected. Through a delivery stroke of a piston hydraulic oil is pumped towards the rubber membrane so that it is stretched and bulged elastically. This will on the other side of the rubber membrane Fuel displaced and through the exhaust valve pushed out. So through the rubber membrane Hydraulic oil area from a fuel area of the Fuel pump disconnected. As I said, it is for everyone Conveyor pistons provided their own rubber membrane, and the Rubber membranes are side by side in the housing arranged.

The disadvantage of the known fuel pump is that a small design of the fuel pump Funding is severely limited.

The object of the present invention is a device of the type mentioned at the outset in such a way that they builds as small as possible and yet sufficient Has delivery capacity.

This task is the beginning of a device mentioned type in that the movable Wall sections arranged in mutually offset levels are.

Advantages of the invention

The fact that the movable wall sections in each other staggered levels are arranged, the movable wall sections in a lateral view from above or "radially overlap" in the radial direction. The lateral or radial dimensions of the movable wall elements can thus be enlarged, without the "lateral" or "radial" Overall dimensions of the corresponding conveyor in this area must be enlarged (under the term They become "lateral" or "radial" Overall dimensions understood in the plane of a membrane).

This leads to an increase in the conveying capacity of the Conveyor device according to the invention without the corresponding conveyor device builds much larger.

Advantageous further developments of the invention Conveying device are specified in subclaims.

In a first further training it is proposed that the Levels in which the movable wall sections are arranged are essentially parallel to each other. The movable wall sections and those between them lying housing elements form a kind "Laminate". Such a composite layer can be simple be assembled what the manufacturing cost of the lowers conveyor device according to the invention.

That further training is very particularly preferred Conveyor device according to the invention, in which at least one of the movable wall sections is elastic Metal membrane. Such a membrane builds a lot flat, and by making them metal, too media and fluids are promoted which for example membranes made of rubber or plastic would attack. Also through the use of membranes made of metal the temperature range in which the device according to the invention can be used, significantly expanded. Due to the high stability of Metal membranes can also have very high differential delivery pressures will be realized.

When using metal membranes, the Arrangement in mutually offset planes is particularly favorable noticeable: due to the system, there is only one with metal membranes comparatively short stroke possible. Due to the Arrangement in mutually offset planes can, however lateral or radial dimensions of the Metal membranes - without increasing the overall housing dimensions - be chosen so large that despite the small diaphragm strokes an adequate delivery rate is guaranteed.

In a further development, a membrane is proposed which has a rest position in which it is due an action by a spring device returns when at least on both sides of the membrane the pressure is roughly the same. This will make the Resetting the metal membrane regardless of the movement the conveying element ensures what at subsequent delivery stroke again a desired maximum Funding guaranteed.

It is even easier if the membrane is designed in this way is that it has a resting position in which it returns due to their inherent elasticity when on both sides of the membrane at least approximately the same There is pressure. In this case, an additional Acting device are waived what on the one hand the manufacturing costs and on the other hand the costs for the assembly of the conveyor device according to the invention reduced.

It is also proposed that the membrane be the conveying element is spherically curved if on both sides of the Membrane is at least approximately the same pressure. As a result, the delivery volume of the metal membrane enlarged without the maximum in the metal membrane occurring tensile stresses are exceeded.

But it is also possible that the membrane essentially is even if at least on both sides of the membrane there is about the same pressure. Especially with one such membrane can be on a separate Reset device can be dispensed with.

Another development of the invention Conveyor is the edge of the membrane is embedded in a sealing ring, which is between two Housing elements is jammed. This sealing ring can for example made of an elastomer material his. Embedding the edge of the metal membrane in one such sealing ring allows it to be in a single Operation to seal the membrane on both sides.

But it is also possible that the edge of the membrane with at least one housing element is welded. hereby is a particularly secure seal on the membrane Housing element created.

Furthermore, the membrane can have at least one sealing web be sealed against a housing element. On such preferably made of metal and in one piece a sealing web connected to the housing element permits one good sealing especially with aggressive media and / or at very high delivery pressures.

To ensure that the maximum allowable Tension in the metal membrane during operation is not can be exceeded, the membrane in one Cavity can be arranged, which at least on one side is delimited by a wall which is at least approximately the Form of the maximum deflected membrane. The wall the cavity thus acts as a stop for the metal membrane.

A particularly simple construction is made possible by that the membrane is part of a surface element. The actual membrane is only through one area this surface element is formed. This area will again, for example, by a corresponding Design of those housing elements defined between which the surface element is arranged.

It is also advantageous if the invention Conveying device comprises a leakage channel, which Leakage fluid from the area of at least one of the removes movable wall sections. This will make the safe separation of the two fluid areas even better guaranteed.

drawing

Figur 1:

eine schematische Darstellung eines Kraftstoffsystems mit einer Hochdruck-Kraftstoffpumpe;

Figur 2:

eine perspektivische Ansicht von hinten eines ersten Ausführungsbeispiels der Hochdruck-Kraftstoffpumpe von Figur 1;

Figur 3:

eine perspektivische Ansicht von vorne der Hochdruck-Kraftstoffpumpe von Figur 2;

Figur 4:

eine Ansicht von vorne der erfindungsgemäßen Hochdruck-Kraftstoffpumpe von Figur 2;

Figur 5:

einen teilweisen Schnitt längs der Linien V-V von Figur 4;

Figur 6:

einen Schnitt längs der Linie VI-VI von Figur 5;

Figur 7:

ein Detail VII von Figur 5;

Figur 8:

einen Schnitt längs der Linie VIII-VIII von Figur 4;

Figur 9:

einen Schnitt längs der Linie IX-IX von Figur 5;

Figur 10:

einen teilweisen Schnitt längs der Linie X-X von Figur 4;

Figur 11:

einen Schnitt längs der Linie XI-XI von Figur 5;

Figur 12:

eine perspektivische Explosionsdarstellung eines Bereichs der Hochdruck-Kraftstoffpumpe von Figur 1;

Figur 13:

eine perspektivische Ansicht von hinten eines zweiten Ausführungsbeispiels der Hochdruck-Kraftstoffpumpe von Figur 1;

Figur 14:

eine perspektivische Ansicht von vorne der Hochdruck-Kraftstoffpumpe von Figur 13;

Figur 15:

eine Vorderansicht der Hochdruck-Kraftstoffpumpe von Figur 13;

Figur 16:

einen Schnitt längs der Linie XVI-XVI von Figur 15;

Figur 17:

einen Schnitt längs der Linie XVII-XVII von Figur 16;

Figur 18:

einen Schnitt längs der Linie XVIII-XVIII von Figur 16;

Figur 19:

ein Detail IXX von Figur 16;

Figur 20:

einen Schnitt längs der Linie XX-XX von Figur 15;

Figur 21:

einen Schnitt längs der Linie XXI-XXI von Figur 16;

Figur 22:

einen Schnitt längs der Linie XXII-XXII von Figur 15;

Figur 23:

einen Schnitt längs der Linie XXIII-XXIII von Figur 16;

Figur 24:

einen Schnitt längs der Linie XXIV-XXIV von Figur 16;

Figur 25:

eine perspektivische Explosionsdarstellung des in Figur 19 dargestellten Bereichs; und

Figur 26:

eine teilweise geschnittene Darstellung ähnlich Figur 5 eines dritten Ausführungsbeispiels der Hochdruck-Kraftstoffpumpe von Figur 1.

Particularly preferred exemplary embodiments of the present invention are explained in detail below with reference to the accompanying drawing. The drawing shows:

Figure 1:

is a schematic representation of a fuel system with a high pressure fuel pump;

Figure 2:

a rear perspective view of a first embodiment of the high pressure fuel pump of Figure 1;

Figure 3:

a perspective view from the front of the high pressure fuel pump of Figure 2;

Figure 4:

a front view of the high pressure fuel pump according to the invention of Figure 2;

Figure 5:

a partial section along the lines VV of Figure 4;

Figure 6:

a section along the line VI-VI of Figure 5;

Figure 7:

a detail VII of Figure 5;

Figure 8:

a section along the line VIII-VIII of Figure 4;

Figure 9:

a section along the line IX-IX of Figure 5;

Figure 10:

a partial section along the line XX of Figure 4;

Figure 11:

a section along the line XI-XI of Figure 5;

Figure 12:

an exploded perspective view of a portion of the high pressure fuel pump of Figure 1;

Figure 13:

a rear perspective view of a second embodiment of the high pressure fuel pump of Figure 1;

Figure 14:

a perspective view from the front of the high pressure fuel pump of Figure 13;

Figure 15:

a front view of the high pressure fuel pump of Figure 13;

Figure 16:

a section along the line XVI-XVI of Figure 15;

Figure 17:

a section along the line XVII-XVII of Figure 16;

Figure 18:

a section along the line XVIII-XVIII of Figure 16;

Figure 19:

a detail IXX of Figure 16;

Figure 20:

a section along the line XX-XX of Figure 15;

Figure 21:

a section along the line XXI-XXI of Figure 16;

Figure 22:

a section along the line XXII-XXII of Figure 15;

Figure 23:

a section along the line XXIII-XXIII of Figure 16;

Figure 24:

a section along the line XXIV-XXIV of Figure 16;

Figure 25:

an exploded perspective view of the area shown in Figure 19; and

Figure 26:

5 shows a partially sectioned illustration similar to FIG. 5 of a third exemplary embodiment of the high-pressure fuel pump from FIG.

Description of the embodiments

A fuel system bears this overall in FIG Reference number 10. It belongs to an internal combustion engine, which, however, is not shown in detail. The Internal combustion engine can, for example, in one Motor vehicle be installed.

The fuel system 10 includes a fuel tank 12, from which an electric fuel pump 14 (Pre-feed pump) delivers the fuel. Of the Electric fuel pump 14 receives the fuel a high pressure fuel pump 16. This is a mechanical connection 18 of a camshaft 20 Internal combustion engine driven.

The high pressure fuel pump 16 compresses the fuel to a very high pressure and promotes it to a Fuel manifold 22 (rail). In this is the Fuel stored under very high pressure. To the Fuel rail 22 is a plurality of injectors 24 connected that have the fuel right in them each inject associated combustion chambers 26.

The construction of the high pressure fuel pump 16 is now under Referring to Figures 2 to 12 explained in detail:

The high pressure fuel pump 16 includes an overall circular cylindrical housing 28, the two housing halves (without reference number) by means of four screws 30 with one another are connected. Protrudes from the housing 28 on one end face (Compare Figure 2) out a drive shaft 32, the End is flattened. This flattened end forms the mechanical connection 18 to the camshaft 20 (see Figure 1). On the other end of the High-pressure fuel pump 16 (see Figure 3) is a Fuel inlet 34 is provided with which the high pressure fuel pump 16 with the electric fuel pump 14 connected is. Next to the fuel inlet 34 is a Fuel outlet 36 is present, which is the high pressure fuel pump 16 with the fuel rail 22 combines.

As can be seen from Figure 5, the drive shaft 32 is in the Housing 28 mounted on a shaft bearing 38. To the end of the drive shaft lying within the housing 28 32, a swash plate 40 is formed. Lean on this sliding shoes 42, in each of which in turn Piston 44 is mounted. There are a total of three sliding shoes 42a - 42c and corresponding pistons 44 are present. From this The arrangement shows that the high-pressure fuel pump 16 around a 3-cylinder axial piston pump is.

The pistons 44 are each one in the longitudinal direction Fluid channel 45 passes through and are in through holes (without reference number) sliding in a guide plate 46 guided. The guide plate 46 is in turn in the housing 28 immovably held and over O-rings (without Reference symbols) sealed. Between the guide plate 46 and the swash plate 40 is inside the housing 28 Fluid space 48 available. Close in the axial direction to the guide plate 46 within the housing 28 of the High pressure fuel pump 16 three housing element plates 50, 52 and 54. Between the rightmost one in FIG. 5 Housing element plate 50 and a paragraph (without Reference numeral) in the fluid channel 45 in the piston 44 is one Spring 56 tensioned.

Again seen from the right to the left in the axial direction in FIG. 5 follows the housing element plate 54 an intermediate plate 58, and further a valve plate 60 and a housing cover 62. The guide plate 46, the Housing element plates 50, 52 and 54, the intermediate plate 58, the valve plate 60, and the housing cover 62 between the two parts of the housing 28 and braced against each other. They all have about that same outside diameter.

Between the housing element plates 50, 52 and 54, as well the intermediate plate 58 are a total of three membranes 64a, 64b and 64c. The membranes 64 are made of one made of thin metal material. The outer edges of the Membranes 64 are each in a sealing ring 66a, 66b, or 66c embedded. The sealing ring 66a is thereby in a groove 67a between the intermediate plate 58 and the housing element plate 54 clamped, the sealing ring 66b in an annular groove 67b between the housing element plate 54 and the housing element plate 52 and the sealing ring 66c in an annular groove 67c between the housing element plate 52 and the housing element plate 50.

The membrane 64a can be shown in more detail below Fluidly associated with the piston 44a, the membrane 64b piston 44b, and diaphragm 64c piston 44c. How for example, is readily apparent from Figure 5 the membranes 64a-64c in mutually parallel planes, which, however, are staggered. The Planes in which the membranes 64a - 64c lie, correspond to the section planes VI, IX and XI in Figure 5. Die Membranes 64a - 64c are not centered on the longitudinal axis of the Piston pump 16, but off-center and in the circumferential direction distributed at an angle of 120 °.

As can be seen in particular from FIGS. 5 and 7 between the housing element plate 50 and the free end of the piston 44a there is a delivery chamber 68a. Of this leads a fluid channel 70a sealed via O-rings 71a the housing element plates 50, 52 and 54 to a spherical concave wall section 72a in the in FIGS end face pointing to the left of the extreme left arranged housing element plate 54. At the same height the wall portion 72a is in that of the housing element plate 54 facing end face of the intermediate plate 58 spherically concave wall section 74a is present.

Both wall sections are for the sake of Clarity only in Figure 7 with reference numerals Mistake. Their shape corresponds essentially to that natural shape of the deflected membrane. At the center is a circular cross section in the intermediate plate 58 having blind hole-like wall section 76a introduced. In this a sheet metal bracket 78a is inserted, the Has a function of a spring and the membrane 64a in the direction of the spherically concave wall portion 72a in the case element plate 54 acted upon.

From the spherically concave wall portion 74a in the Intermediate plate 58 leads to a fluid channel 80a elongated and radially extending recess 82a to which an inlet valve 84a and an outlet valve 86a in FIG the valve plate 60 are fluidly connected. The Inlet valve 84a is connected via an annular channel 83 to the Fuel inlet 84, the exhaust valve 86a via a Annular channel 85 connected to the fuel outlet 36.

In Figures 5 and 7 those elements are in detail visible and explained in connection with the Cylinder a of the piston 44a stand. Are in an analogous manner from FIGS. 8 and 9 also those elements and Areas apparent that are related to the cylinder of the piston 44b, but not for the sake of simplicity all reference signs are entered. Those elements and Areas related to the cylinder of the piston 44c stand, go from Figures 10 and 11 in detail out. Since the individual cylinders a, b and c are constructed essentially identically, the Elements and areas of cylinders b and c are not repeated all explained in detail. Each cylinder is a, b, and c its own, staggered to the other Membrane 64a, 64b, and 64c is assigned. This The facts arise in particular from the perspective exploded view in Figure 12.

The operation of those shown in Figures 2 to 12 High-pressure fuel pump 16 is now based on the example of Cylinder a explained in detail:

Rotation of the drive shaft 32 also results in Rotation of the swash plate 40 and subsequently to a back and forth Movement of the piston 44a. The installation of the slide shoe 42a on the swash plate 40 is thereby by the spring 56th guaranteed. About not visible in the figures Oil flows from the internal combustion engine into the fluid path Fluid space 48. But it is also possible that in space 48 included oil volume (single oil filling) is present. It arrives from room 48, at the bottom dead center of the piston via a groove 89 into the fluid channel 45a and further into the Funding room 68a. When the piston 44a to the housing element plate 50 moves there, the oil from the delivery room 68a via the fluid channel 70a into the space between the Membrane 64a and the spherically concave wall section 72a pressed.

As a result, the metal membrane 64a is moved from its into the Figures 5 and 7 shown rest position, in which they abuts against the spherically concave wall section 72a the force of the sheet metal bracket 78a moved out until it on the spherically concave wall portion 74a abuts. Doing so which is initially between the membrane 64a and the spherical concave wall section 74a existing fuel over the Fluid channel 80a, the depression 82a, the outlet valve 86a and the ring channel 85 into the fuel rail 22 pressed.

As the swash plate 40 rotates further, the Piston 44a from the spring 56 again from the housing element plate 50 pushed away. As a result, the oil flows from the spherically concave between the membrane 64a and de Wall portion 72a formed cavity over the fluid channel 70a back into the delivery room 68a. The membrane 64a is supported by the sheet metal bracket 78a acting as a spring, back to the spherically concave wall section 72a pressed until it is essentially flat again is applied. This movement of the membrane 64a closes this Exhaust valve 68a, and at a corresponding Differential pressure opens inlet valve 84a. So can Fuel from the fuel inlet 34 via the ring channel 83 and the inlet valve 84a in between the membrane 64a and the cavity resulting in the wall portion 74a.

A reference will now be made to Figs second embodiment of a high pressure fuel pump 16 explained. Such elements and areas what equivalent functions to elements and areas that shown in Figures 1 to 12 Embodiment have the same reference numerals. They are not explained in detail again.

A major difference from that in FIGS. 13 to 25 high pressure fuel pump shown to that of Figures 2 to 12 consists of the type of membranes 64a and the housing element plates 50 - 54 and the Intermediate plate 58. As in particular from FIG. 19 can be seen, in turn, the corresponding Elements and areas of the cylinder a of the high pressure fuel pump 16 is shown in the Intermediate plate 58 facing side of the housing element plate 54 no spherically concave wall section available. Instead, it is that of the intermediate plate 58 facing surface of the housing element plate 54 completely flat.

Furthermore, the membrane 64a is covered by a section of a Surface element 88a formed, the diameter of the Diameters of the housing element plates 50 - 54 and the Intermediate plate 58 corresponds. Ultimately, the membrane 64a formed by that area of the surface element 88a, which in the area of the spherically concave wall section 74a in the housing element plate 54 facing End face of the intermediate plate 58 lies. This Wall section 74a is as in the previous one Embodiment, with respect to the longitudinal axis of the High-pressure fuel pump 16 arranged off-center.

Another difference from the previous one Embodiment is that also no spring or there is no sheet metal bracket 78a. In the 16 and 19 flat rest position shown, in which they are flat on the housing element plate 54 is present, the membrane 64a essentially reverses their own elasticity. Overall, the Diameter of the membranes 64a - 64c or the Wall sections 74a-74c in the case of FIGS. 13 to 25 Embodiment shown larger than that in the Figures 2 to 12 embodiment shown despite the smaller stroke of the membranes 64a-64c to provide sufficient funding. By the Elimination of the bracket 78 and the lower total stroke of the Membranes 64a - 64c are built in FIGS. 13 to 25 shown high pressure fuel pump 16 in the axial Overall shorter.

Another difference between the two said Embodiments consist in the sealing of the Membranes 64a-64c opposite the housing element plates 50 - 54 or opposite the intermediate plate 58: Instead of an elastomeric sealing ring that fits into an annular groove is inserted are on the housing element plates 50-54 and 58 sealing webs 66 formed on the intermediate plate (see Figures 17, 18, 21, 23, 24 and 25). These are worked plan and reduce the contact surface between the membranes 64 and the housing element plates 50-54 or the intermediate plate 58. The reduced The contact surface in turn leads to a higher one Surface pressure and for a better sealing effect. A Recess 90 in the radially outer sealing web 66 enables the unhindered exit, if any Leak fluid. For this purpose, the recess 90 is not over channels shown with the upstream of the inlet valve 84 connected area.

Another embodiment is shown in FIG High pressure fuel pump 16 shown. The same applies here, that such elements and areas which are equivalent Functions related to elements and areas of the above have described embodiments, the same Wear reference numerals and not explained again in detail are. With regard to the design of the housing element plates 50 - 54, the intermediate plate 58, and the Membranes 64 correspond to the high-pressure fuel pump 16 of Figure 26 the embodiment which in the Figures 13 to 25 is shown. However, it does the high-pressure fuel pump 16 of FIG. 26 not an axial piston pump, but a 3-cylinder radial piston pump.

In an embodiment not shown, there are none Sealing webs provided. Instead, the membranes are with the corresponding housing elements welded.

Claims (13)

Device for conveying a fluid, in particular fuel pump (16), with at least two cyclically operating conveying elements (44), which convey a first fluid to one side of a movable wall section (64) which is assigned to a conveying element (44) and the other Side is connected to an inlet (34) and an outlet (36) for a second fluid, characterized in that the movable wall sections (64) are arranged in mutually offset planes (VI, IX, XI). Device (16) according to claim 1, characterized in that the planes (VI, IX, XI) in which the movable wall sections (64) are arranged are substantially parallel to one another. Device (16) according to one of claims 1 or 2, characterized in that at least one of the movable wall sections comprises an elastic membrane (64) made of metal. Device (16) according to claim 3, characterized in that the membrane (64) has a rest position into which it returns due to the action of a spring device (87), if on both sides of the membrane (64) at least approximately the same pressure prevails. Device (16) according to one of claims 3 or 4, characterized in that the membrane (64) has a rest position, into which it returns due to its inherent elasticity when there is at least approximately the same pressure on both sides of the membrane (64). Device (16) according to one of Claims 3 to 5, characterized in that the membrane (64) is spherically curved toward the conveying element (44) when at least approximately the same pressure prevails on both sides of the membrane (64). Device (16) according to any one of claims 3 to 6, characterized in that the membrane (64) is substantially flat when there is at least approximately the same pressure on both sides of the membrane (64). Device (16) according to one of claims 3 to 7, characterized in that the edge of the membrane (64) is embedded in a sealing ring (66) which is clamped between two housing elements (50, 52, 54, 58). Device (16) according to one of claims 3 to 8, characterized in that the edge of the membrane is welded to at least one housing element. Device according to one of claims 3 to 9, characterized in that the membrane (64) is sealed off from a housing element (50, 52, 54, 58) via at least one sealing web (66). Device (16) according to one of claims 3 to 10, characterized in that the membrane (64) is arranged in a cavity which is delimited at least on one side by a wall section (74, 76) which is at least approximately the shape of the maximum deflected membrane (64). Device (16) according to one of claims 3 to 11, characterized in that the membrane (64) is part of a surface element (88). Device (16) according to one of the preceding claims, characterized in that it comprises a leakage channel (90) which discharges leakage fluid from the area of at least one of the movable wall sections (64).

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