EP1273796B1 - High pressure fuel pump especially for direct injection internal combustion engine and fuel system and internal combustion engine - Google Patents

Description

State of the art

The invention relates to a high-pressure fuel pump, in particular for direct injection internal combustion engines, with a housing having a low pressure inlet and a High pressure outlet, with one in the housing existing pump room, which with the low-pressure inlet and the high-pressure outlet is connectable, with a control valve, which directly the pump room with the low-pressure inlet can connect and opens to the low-pressure inlet, and with a check valve with a separate from the control valve Valve element which between low-pressure inlet and Pump room is arranged and directly to the pump room opens.

Such a high-pressure fuel pump is known from DE 198 34 120 A1 known. This high pressure fuel pump is included Fuel supply systems with two series connected Fuel pumps used. From the pump room branches on the one hand Flow channel, which via a check valve to a Low pressure inlet leads. On the other hand leads another Flow channel from the pump chamber to a control valve, which with another flow channel in the housing of the high-pressure fuel pump which is also connected to the low pressure inlet leads. On the outlet side, the pump room is also over a check valve connected to a high pressure outlet.

In the known high pressure fuel pump is a piston pump. To the pumped to the high-pressure outlet To control the amount of fuel, the control valve be opened during a delivery stroke of the pump piston. As a result, the pump space is the low-pressure inlet opened and no more fuel to the high pressure outlet promoted.

Alternatively, the control valve could also be at the beginning of a Delivery stroke of the pump piston to be opened. The control the delivery rate by a variation of the delivery end has however, several advantages:

On the one hand, the control valve can be made simpler, because the flow cross-section to be controlled considerably smaller can be executed. Since the pump piston mostly from a Drive cam is driven, the load of the falls Drive cam lower, since the promotion before the upper Dead center of the pump piston is terminated (at top dead center of the pump piston occurs due to the small radius of curvature the highest Hertzian pressure). Finally, it turns out still a cost advantage in that the control of the Control valve can be done via a switching power amplifier.

EP 0 078 983 A1 and EP 0 816 672 A2 describe a High pressure pump with a control valve, which with a Inlet valve is connected in series.

The object of the present invention is a high-pressure fuel pump of the type mentioned at the beginning, that it builds easier overall and thus cheaper can be produced.

This task is in a high-pressure fuel pump of mentioned type achieved in that the Check valve and the control valve in a common Valve module are housed, which at least partially inserted into the pump housing and for the Control valve and the check valve a common Having connection to the low-pressure inlet out, and that the Elements of the check valve and the elements of the Control valve to each other coaxially arranged in the valve module are.

Advantages of the invention

In the high-pressure fuel pump according to the invention are Inlet valve through which the fuel from the low pressure inlet flows into the pump room during a suction stroke, and that Control valve, which towards the end of a delivery stroke of the Pump piston opens, integrated into a common unit. This unit can be pre-assembled. Due to the better accessibility, such an assembly is easier perform at a cost advantage, but also at a cost Quality increase leads.

In addition, in the housing of the invention High-pressure fuel pump only a few flow channels required because the common valve module for the Check valve and the control valve a common Having connection to the low pressure inlet out. to Manufacture of the housing of the high-pressure fuel pump are thus less processing steps required what the Production costs for the high-pressure fuel pump according to the invention lowers.

In addition, due to the coaxial arrangement of the Space available particularly well exploited, so that especially for the check valve a large and thus favorable flow cross-section can be achieved.

Advantageous developments of the invention are in Subclaims specified.

In a further development it is suggested that the Control valve is radially inward and the check valve a Includes a plurality of flow channels, which radially outward to at least a portion of the control valve in the valve module are provided. Through this plurality of flow channels becomes a comparatively large flow cross section for the Check valve created so that during a suction stroke the pump piston rapid filling of the pump chamber possible is. To the low pressure inlet are the flow channels preferably interconnected by an annulus. The Control valve in turn is at least with its valve element radially inside the flow channels. Such a high pressure fuel pump is very effective and still builds a lot compact.

It is particularly preferred if the check valve a disc-annular valve element comprises. Such Valve element is as well as the associated valve seat easy to manufacture.

The valve dynamics of the check valve is the better, depending less the mass of the valve element of the check valve is. This is taken into account in that training, in the valve element of the check valve is a thin one Includes platelets.

Also, the check valve as a double seat valve be educated. In this case already stands at low Valve lift a large flow area available.

In a particularly preferred embodiment of The high-pressure fuel pump according to the invention comprises Valve module to the pump room at least one Support section, on which a biasing element is supported, which the valve element of the check valve against the associated valve seat acted upon. The bias of the Biasing element is preferably just so strong that the valve element of the check valve already at a low pressure difference from the associated valve seat lifts. Is the support section, as proposed, on Valve module arranged, the complete unit can off Check valve and control valve are pre-assembled, which reduces the production costs again.

It is particularly preferred if the support section formed integrally with a common valve housing is.

The invention also relates to a fuel system with a Fuel tank, with at least one fuel injection device, which the fuel directly into the Injecting combustion chamber of an internal combustion engine, with at least one high-pressure fuel pump, and with a Fuel manifold to which the fuel injector connected.

Such a fuel system is used in internal combustion engines used with direct fuel injection. The pressure in the fuel rail, which is commonly referred to as "Rail" is referred to as the high-pressure fuel pump applied.

In order for the fuel system to be simpler overall is and can be made cheaper suggested that the high-pressure fuel pump in the above type is formed.

The invention further relates to an internal combustion engine with at least one combustion chamber into which the fuel injected directly. To the internal combustion engine overall easier to build and their production to make cheaper, as well as to the operation of the To make the internal combustion engine more reliable suggested that they have a fuel system of the above has mentioned type.

drawing

Fig. 1:

einen teilweisen Schnitt durch einen Bereich eines ersten Ausführungsbeispiels einer Hochdruck-Kraftstoffpumpe;

Fig. 2 bis 4:

eine stark vereinfachte Darstellung des Bereichs von Fig. 1 zu unterschiedlichen Zeitpunkten während des Betriebs der Hochdruck-Kraftstoffpumpe;

Fig. 5:

ein Diagramm, in dem das Fördervolumen der Hochdruck-Kraftstoffpumpe der Fig. 1 - 4 über der Zeit aufgetragen ist;

Fig. 6:

ein Diagramm, in dem der Öffnungszustand eines Steuerventils der Hochdruck-Kraftstoffpumpe der Fig. 1 - 4 über der Zeit aufgetragen ist;

Fig. 7:

eine schematisierte und teilweise geschnittene Darstellung eines Bereichs eines nicht erfindungsgemäßen Ausführungsbeispiels einer Hochdruck-Kraftstoffpumpe; und

Fig. 8:

ein schematisiertes Blockschaltbild einer Brennkraftmaschine mit einem Kraftstoffsystem und einer Hochdruck-Kraftstoffpumpe gemäß Fig. 1.

Hereinafter, embodiments of the invention will be explained in detail with reference to the accompanying drawings. In the drawing show:

Fig. 1:

a partial section through a portion of a first embodiment of a high-pressure fuel pump;

2 to 4:

a greatly simplified representation of the range of Figure 1 at different times during operation of the high-pressure fuel pump.

Fig. 5:

a diagram in which the delivery volume of the high-pressure fuel pump of Figures 1 - 4 is plotted against time.

Fig. 6:

a diagram in which the opening state of a control valve of the high-pressure fuel pump of Figures 1 - 4 is plotted against time.

Fig. 7:

a schematic and partially sectioned view of a portion of a non-inventive embodiment of a high-pressure fuel pump; and

Fig. 8:

a schematic block diagram of an internal combustion engine with a fuel system and a high-pressure fuel pump according to FIG. 1.

Description of the exemplary embodiments

In Fig. 1 carries a high-pressure fuel pump in total the reference number 10. From her is in the figure only one End area shown. The high pressure fuel pump 10 comprises a housing 12 into which a stepped bore 14 is introduced. Transversal to the longitudinal axis of Stepped bore 14 are in the housing 12 also two Flow channels 16 and 18 available. The upper in Fig. 1 Flow channel 16 leads to a low-pressure inlet 20 for the fuel. The lower in Fig. 1 flow channel 18th leads to a high-pressure outlet 22. In a lower Region 24 of the stepped bore 14 is a pump piston 26 guided axially movable. In an upper area 28 of the Stepped bore 14, a valve housing 30 is inserted. This is opposite the stepped bore 14 by an O-ring seal 32 sealed, which in an annular groove (without Reference numeral) inserted in the wall of the stepped bore 14 is. Between the valve housing 30 and the pump piston 26th is a pump room 34 available.

In the valve housing 30, a check valve 36 and housed a control valve 38. On the exact Training will be referred to in detail below. On the valve housing 30 is an actuating unit 40 placed. The operating unit 40 is opposite to Pump housing 12 sealed by an O-ring seal 42, in an annular groove (without reference numeral) in the top the pump housing 12 is inserted. The operating unit 40 is about screws (without reference numeral) on the pump housing 12 attached. Your task is detailed below explained. The attachment of the actuator unit 40 am Valve housing 30 is inseparable via a flange 41st Die Actuator 40, the control valve 38, the Non-return valve 36 and the valve housing 30 form together a valve module 44th

The valve housing 30 has a total cylindrical shape. It becomes in its longitudinal direction of a centric Stepped bore 46 interspersed. In the stepped bore 46 is in Fig. 1 from above a rod-shaped valve element 48th introduced, which with a rounded end with a in Fig. 1 lower portion of the stepped bore 36 existing Valve seat 50 cooperates. The valve element 48 and the valve seat 50 are part of the control valve 38.

The valve element 48 extends upwardly out of the Valve housing 30 out in the actuator 40th into it. At the end remote from the valve seat 50 of the Valve element 48 is a cylindrical armature 52 is attached. A lid 56 closes the operating unit 40 upwards down. Further, in the actuator unit 40 a annular magnet 86 is provided, which at a Energizing the armature 52 moves in Fig. 1 down, so that the valve element 48 is pressed into the valve seat 50 becomes.

Below the valve seat 50, the stepped bore 46 forms a flow channel 58, which opens into the pump chamber 34. Above the valve seat 50, the stepped bore 46 has a larger diameter than the valve element 48, so that a Valve chamber 60 is formed. This is about a majority of radially extending flow channels 62 with a circumferential groove 64 connected in the outer wall of the Valve housing 30 is introduced. In the in Fig. 1 shown installation position is the groove 64 at the height of a extended portion 66 of the stepped bore 14 in Pump housing 12. As a result, an annular space 68 is formed. From this branches to the low pressure inlet 20 out of the already introduced above Stömungskanal 16 from.

The check valve 36 is constructed as follows: In the valve housing 30 extend from the circumferential groove 64th a plurality of substantially axial flow channels 70 obliquely down and slightly radially inward. In the in Fig. 1 illustrated embodiment are a total of four in Circumferentially arranged evenly distributed Flow channels 70 present, of which in Fig. 1 two are visible. The flow channels 70 open into the Bottom of the valve body 30. The openings of the Flow channels 70 in the bottom of the valve housing 30th There are surrounded by an annular valve seat 72. This consists of a valve housing 30 coaxial and radially inner ring land 72a and a likewise to Valve body 30 coaxial and radially outer annular land 72b.

On the annular valve seat 72 on the bottom of the Valve housing 30 is powered by a small force Compression spring 74 a disc-annular valve element 76th pressed. In the disc-annular valve element 76th it is a thin metal plate. The Compression spring 74 is supported on an axially extending annular support member 78 from. This is with his upper edge welded to the valve housing 30. At his In Fig. 1 lower end, the support member 78 a radially inwardly facing annular web 80 on which the Compression spring 74 is applied. At the disc-ring-shaped Valve element 76 of the check valve 36 are above the Circumference distributed radial recesses 82 available. in the Support member 78 are corresponding, not in the figure visible openings provided.

As readily apparent from Fig. 1 it can be seen on the one hand, the elements of the check valve 36, so the Plurality of axial flow channels 70 and annular Valve seats 72, the compression spring 74, the disc-annular Valve element 76 and the support member 78, coaxial with the Elements of the control valve 38, ie in particular the Stepped bore 46 in the valve housing 30, the valve element 48th and the valve seat 50. Furthermore, recognizes one, that the circumferential groove 64 has a common connection the check valve 36 and the control valve 38 for Low-pressure inlet forms.

As another element of the high pressure fuel pump 10 is a check valve 84 mentioned, which in the lower Flow channel 18 between the pump chamber 34 and the High-pressure outlet 22 is present. In this Check valve 84 is a normal one spring loaded ball valve leading to the high pressure outlet 22 opens.

The high pressure fuel pump 10 operates as follows (See also Fig. 2 - 6, it should be noted that in particular in FIGS. 2 to 4 for reasons of illustration not all parts and reference signs are shown; Further, in Figures 2 to 4, the control valve 38 and the check valve 36 in one of Figure 1 different orientation relative to the longitudinal axis of Piston 26 shown):

As is apparent from Figs. 2-4, is the Pump piston 26 driven by a cam 88, which on a clockwise rotating shaft 90 is attached. In general, the shaft 90 is directly from a crankshaft of an associated internal combustion engine driven. In the illustrated in Fig. 2 operating state the high-pressure fuel pump 10 moves the Pump piston 26 down (suction stroke, see Fig. 5). This increases the pump space 34. The pressure in Pumping chamber 34 is in this operating state of the high-pressure fuel pump 10 lower than the pressure at the high pressure outlet 22, so that the check valve 84 is closed is. The magnet 86 of the control valve 38 is in this Operating state of the high pressure fuel pump 10 energized. Thus, the valve element 48 against the valve seat 50th pressed; the control valve 38 is thus closed (see. Fig. 6, left area).

When the pressure difference between the pumping space 34 and the Low-pressure inlet 20 exceeds a certain level lifts the disc-annular valve element 76 of the Check valve 36 from the bottom of the valve housing 30 and the existing there valve seat 72 from. Thus, can Fuel from low pressure inlet 20 over the top Flow channel 16, the annular space 68 and the axial Flow channels 70 flow into the pump chamber 34, whereby this is filled with fuel.

The fuel flows on the one hand between the disc-annular valve element 76 and the radial inner ring land 72a and the central opening (without Reference numeral) in the disc-annular valve element 76 for Pumping room 34. On the other hand, fuel also flows between the radially outer ring land 72b and the disc-annular valve element 76 through the radial Recesses 82 and the corresponding recesses in the Support member 78 in the pump chamber 34. In that regard, that is Check valve 36 thus formed as a double seat valve.

This has the advantage that a lesser valve lift adjusts, which is especially at high speed and thus rapid movements of the pump piston 76 in terms of the desired valve dynamics is an advantage.

After reaching the bottom dead center of the Pump piston 26 is pressed by the cam 88 back up (see Fig. 3). This movement is also called delivery designated (see Fig. 5). Since in the pump room 34 now a higher pressure than in the low-pressure inlet 20, is the disc-annular valve element 76 of the Check valve 36 against the valve seat 72 at the Bottom of the valve body 30 pressed. The Check valve 36 is thus closed. The Valve element 48 of the control valve 38 is still over the magnet 86 is pressed against the valve seat 50. That too Control valve 38 is thus closed.

Thus, the pressure of the pump chamber 34 increases enclosed fuel. This happens until the pressure difference between in the pump room 34th enclosed fuel and fuel at High-pressure outlet 22 is so large that the check valve 84 opens. Then the fuel flows out of the pumping space 34 through the lower flow passage 18 to the high-pressure outlet 22 of the high-pressure fuel pump 10 out.

So that the pressure of the fuel at the high-pressure outlet 22 does not exceed a certain value, that of the High-pressure fuel pump 10 to the high-pressure outlet 22 out subsidized fuel quantity to be controlled. this happens in that during the delivery stroke of the magnet 86 of the Control valve 38 is turned off. This will be the Anchor 52 by the pressure in the pump chamber 34 in Fig. 1 upwards emotional. Thus, the valve element 48 lifts from the valve seat 50 (see Fig. 6, center), so that fuel from the Pumping chamber 34 via the stepped bore 46 and the annular space 68th to the upper flow passage 16 and the low-pressure inlet 20th can flow out. Since now the pressure in the pump room 34 (abruptly) sinks again, closes the check valve 84, so that no fuel from the high-pressure outlet 22 via the pump chamber 34 to the low-pressure inlet 20 to flow out can.

The opening of the control valve 38 towards the end of a delivery stroke is otherwise shown in Fig. 4. By a suitable Choice of the time at which the control valve 38 during opens a delivery stroke, which can during a delivery stroke pumped from the pumping chamber 34 to the high-pressure outlet 22 towards Fuel quantity to be adjusted.

In Fig. 7 is a not according to the invention Embodiment of a High pressure fuel pump 10 shown. Such elements, Areas and components that are functionally equivalent to Elements, areas and components of the in Figs. 1-6 described embodiment, wear same reference numerals and are not again in detail explained.

The difference to the one described above invention Embodiment relates to the arrangement of Check valve 36 and the control valve 38. While at that shown in Figs. 1-6 invention Embodiment of a High-pressure fuel pump 10, the check valve 36 and the control valve 38 were arranged coaxially with each other, is in the embodiment shown in Fig. 7 that Control valve 38 is disposed adjacent to the check valve 36.

Fig. 8 shows an internal combustion engine 92, in which a Fuel system 94 is installed. This includes one Fuel tank 96, from which an electric Fuel pump 98 supplies the fuel to a low pressure inlet 20 promotes a high-pressure fuel pump 10. The High-pressure fuel pump 10 is in the in Figs. 1-6 or constructed in Fig. 7 illustrated type.

From a high pressure outlet 22 of the high pressure fuel pump 10, the fuel becomes a fuel rail, commonly referred to as a "rail", promoted. The fuel rail has that Reference numeral 100. To the fuel rail 100 are several high-pressure injectors, for example Injectors 102, connected. These inject the Fuel directly into corresponding combustion chambers 104 a. Of the Pressure in the fuel rail 100 is from a Pressure sensor 106 detected. This provides appropriate Signals to a control and / or regulating device 108. This again, the magnetic control valve (in FIG. 8) controls without reference numeral) of the high pressure fuel pump 10 to the pressure in the fuel rail 100 in the sense a closed system on a desired To keep level.

Claims (9)

1. High-pressure fuel pump, especially for direct injection internal combustion engines (92), having a housing (12) which has a low-pressure inlet (20) and a high-pressure outlet (22), having a pump chamber (34) which is located in the housing (12) and can be connected to the low-pressure inlet (20) and to the high-pressure outlet (22), having a control valve (38), which can directly connect the pump chamber (34) to the low-pressure inlet (20) and opens into the low-pressure inlet (20), and having a non-return valve (36) with a valve element (76) which is separate from the control valve (38) and which is arranged between the low-pressure inlet (20) and the pump chamber (34) and opens directly into the pump chamber (34), characterized in that the non-return valve (36) and the control valve (38) are accommodated in a common valve module (44) which is inserted at least partially into the pump housing (12) and has a common connection (64) to the low-pressure inlet (20) for the control valve (38) and for the non-return valve (36), and in that the elements of the non-return valve (36) and the elements of the control valve (38) are arranged coaxially with respect to one another in the valve module (44).
2. High-pressure fuel pump (10) according to Claim 1, characterized in that the control valve (38) is located radially on the inside, and the non-return valve (36) comprises a plurality of flow ducts (70) which are provided radially on the outside about at least one region of the control valve (38) in the valve module (44).
3. High-pressure fuel pump (10) according to Claim 2, characterized in that the non-return valve (36) comprises a disc-ring-shaped valve element (76).
4. High-pressure fuel pump (10) according to one of the preceding claims, characterized in that the valve element of the non-return valve (36) comprises a small thin plate (76).
5. High-pressure fuel pump according to one of the preceding claims, characterized in that the non-return valve (36) is embodied as a double seat valve.
6. High-pressure fuel pump according to one of the preceding claims, characterized in that the valve module (44) comprises at least one supporting section (78) in the direction of the pump chamber (34), a prestressing element (74) which loads the valve element (76) of the non-return valve (36) in the direction of the associated valve seat (72) being supported on said supporting section (78).
7. High-pressure fuel pump (10) according to Claim 6, characterized in that the supporting section (78) is embodied in one piece with a common valve housing (30).
8. Fuel system (94) having a fuel container (96), having at least one fuel injection device (102) which injects the fuel directly into the combustion chamber (104) of an internal combustion engine (92), having at least one high-pressure fuel pump (10) and having a fuel collecting line (100) to which the fuel injection device (102) is connected, characterized in that the high-pressure fuel pump (10) is embodied according to one of Claims 1 to 7.
9. Internal combustion engine (92) having at least one combustion chamber (104) into which the fuel is directly injected, characterized in that it has a fuel system (94) according to Claim 8.

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