EP3631189B1 - High-pressure fuel pump and fuel filter device - Google Patents

Description

State of the art

The invention relates to high-pressure fuel pumps and fuel filter devices according to the preambles of the independent claims.

the DE 10 2014 225 319 A1 describes a high-pressure fuel pump with a housing, an inlet, a delivery section, and an outlet. The high-pressure fuel pump is designed as a piston pump, and the delivery section accordingly includes a pump piston. Although a fuel filter device in the DE 10 2014 225 319 A1 not explicitly mentioned, but one is usually present in order to keep contaminants present in the fuel away from sensitive areas of the high-pressure fuel pump. The filter device is usually designed in the manner of a cylindrical pot, the flow through the filter section being from the outside inwards and the fuel flowing out of the filter device through the annular base section.

From the EP 1126162 A1 a solenoid valve for controlling the fuel delivery pressure of an internal combustion engine is known, which has fuel filter means.

From the DE 10 2013 201897 A1 a valve for metering fluid is known which has a flow channel for the fluid leading from a fluid inlet to a metering opening and a filter device arranged in the flow channel through which the fluid flows.

Disclosure of Invention

The problem on which the invention is based is solved by high-pressure fuel pumps and fuel filter devices with the features of the independent claims.

A high-pressure fuel pump not according to the invention comprises a pump housing, an inlet, a fuel filter device, a delivery section and an outlet. The fuel filter device has an annular base section and an overall at least approximately cylindrical filter section extending therefrom. The filter section, in turn, has a plurality of web sections extending longitudinally from the base section. A screen section is arranged between each two adjacent web sections. The fuel filter assembly also includes a cap-like end portion remote from the base portion in the longitudinal direction. A first edge area of the screen section adjacent to the base section and/or a second edge area of the screen section adjacent to the end section are/is concavely curved towards this center when viewed from a center of the screen section lying in the plane of a lateral surface of the cylindrical filter section.

Compared to the prior art, the high-pressure fuel pump, which is not according to the invention, has an increased service life and reliability, as well as an improved pump performance over the service life. This is achieved in that the web sections are reinforced in the axial edge regions of the screen sections by being made wider as seen in the circumferential direction. This is in turn caused by the fact that the first axial edge area or the second axial edge area of a screen section is concavely curved as viewed from the center of the screen section. Overall, rounded edge areas of a sieve section are realized in this way in the top view. It goes without saying that the concave curvature that is meant here is not the curvature around a longitudinal axis of the fuel filter device that is already present and runs in the circumferential direction. Rather, the concave curvature referred to here lies more or less in the plane of a cylindrical lateral surface of the fuel filter device and runs in the axial direction, so to speak.

The high-pressure fuel pump, which is not according to the invention, and the corresponding fuel filter device are based on the knowledge that when there is a flow through the fuel filter device from the outside to the inside, as is the case with numerous high-pressure fuel pumps, there is a risk that a screen section that is Seen from the longitudinal axis of the fuel filter device, it actually curves outwards, folds inwards. This applies in particular when dirt particles have accumulated on the filter section. This also results in considerable bending stress on the web sections, especially in those areas that are adjacent to the base section or end section, which increases the risk of a web section breaking in these areas. This applies in particular when a screen section flaps back and forth as a result of load changes. However, these are precisely those areas which are now wider and thus reinforced due to the design according to the invention, which in turn reduces the risk of breakage in these areas.

It is true that the measure reduces the area of a screen section available for the throughflow. However, it has been found that this reduction has only a slight or negligible effect on the efficiency or the pumping capacity of the high-pressure fuel pump.

In a first development, it is proposed that the first and/or the second edge area be elliptically or parabolically or circularly curved. An elliptical or parabolic curvature has the advantage that the widening of the web sections in the immediate vicinity of the base section and/or the end section is particularly large. If an ellipse is used as the basic geometry, it can be created from a conic or cylindrical section.

It is also possible that, viewed in the longitudinal direction, the length of the curved first edge area, which is therefore adjacent to the base section, is greater than the length of the curved second edge area, which is therefore adjacent to the end section. This is based on the consideration that when the corresponding screen section folds inwards due to the flow from the outside inwards, that area of the screen section which then has the smallest distance to the longitudinal axis of the fuel filter device and thus throttles the most, is not in the middle between the base section and the end section, but is shifted towards the end section, i.e. is closer to the end section than to the base section. An overall larger cross-section is therefore available for the fuel to flow out of the fuel filter device, as a result of which the total pressure drop across the fuel filter device is reduced.

Furthermore, it is particularly advantageous if a lateral transition region between a web section and the end section and/or the base section is concave when viewed from the outside. Where there were relatively sharp notches in prior art fuel filter assemblies, notch-reducing radii are used in accordance with the present invention, thereby reducing localized stresses, which increases the life of the fuel filter assembly. This is possible in particular because of the concave curvature of the first and second edge regions provided according to the invention.

The high-pressure fuel pump according to the invention is basically identical in structure to the high-pressure fuel pump mentioned above, which is not according to the invention. However, unlike the first high-pressure fuel pump according to the invention, the strainer section of the fuel filter device is not curved radially outward in the normal state, but is essentially flat overall, so that the filter section has an overall polygonal cross section. Due to the principle, such a screen section cannot fold inwards even under the highest pressure load, for example due to dirt particles accumulated on the screen section, which means that the reduction in the possible outflow cross section and the resulting increase in flow resistance that would otherwise occur when flaps inwards do not occur.

In this case, the measure according to the invention means that the area of a screen section available for the throughflow is reduced compared to a screen section curved radially outwards. However, it has again been found that in practice this reduction hardly affects the efficiency or the pump performance of the high-pressure fuel pump.

Figur 1

einen ersten Längsschnitt durch eine erfindungsgemäße Kraftstoff-Hochdruckpumpe;

Figur 2

einen zweiten Längsschnitt durch die Kraftstoff-Hochdruckpumpe von Figur 1 längs einer Linie II-II;

Figur 3

eine perspektivische Darstellung einer nicht erfindungsgemäßen Kraftstoff-Filtereinrichtung der Kraftstoff-Hochdruckpumpe der Figuren 1 und 2;

Figur 4

einen Schnitt durch einen Endabschnitt der Kraftstoff-Filtereinrichtung von Figur 3; und

Figur 5

einen Schnitt durch eine erfindungsgemäße Kraftstoff-Filtereinrichtung.

Embodiments of the invention will be explained below with reference to the accompanying drawings. Show in the drawing:

figure 1

a first longitudinal section through a high-pressure fuel pump according to the invention;

figure 2

a second longitudinal section through the high-pressure fuel pump figure 1 along a line II-II;

figure 3

a perspective view of a fuel filter device not according to the invention of the high-pressure fuel pump figures 1 and 2 ;

figure 4

a section through an end portion of the fuel filter device of figure 3 ; and

figure 5

a section through a fuel filter device according to the invention.

A high-pressure fuel pump contributes to the figures 1 and 2 overall reference numeral 10. It comprises a pump housing 12 which has a substantially cylindrical or rotationally symmetrical shape. In a side wall of the pump housing 12 is as shown figure 1 As can be seen, an inlet 14 is formed by an inlet connection piece 16 which is welded to the pump housing 12 . A first fluid channel section 18 runs inward in the radial direction in the pump housing 12 from the inlet 14 . It merges into a second fluid channel section 20, which runs upwards in the axial direction in the pump housing 12, up to a pressure damper device 22. This is a diaphragm damper, which is not described further here. The pressure damper device 22 is accommodated in a damper chamber 24 which is formed between an upper face 26 of the pump housing 12 and a housing cover 28 welded onto the pump housing 12 . The fluid channel section 20 opens into the damper chamber 24.

How out figure 2 As can be seen, a third fluid channel section 30 extends from the upper end face 26, ie away from the damper chamber 24, to in front of an inlet valve 32, which is designed as a quantity control valve. This means that the inlet valve 32 can be held in an open position in a manner that is not described in detail here. In principle, the inlet valve 32 is designed as a non-return valve which opens towards a conveying chamber 34 . The pumping chamber 34 is essentially delimited by a wall of a blind hole (no reference number) extending axially in the pump housing 12 and a pump piston 36. The pump piston 36 is guided in a piston bushing (no reference number) with a sliding fit and can be moved in the axial direction. The delivery chamber 34 and the pump piston 36 together form a delivery section 38.

A fourth fluid channel section 40 branches off in the radial direction from the conveying chamber 34 and leads via an outlet valve 42 designed as a check valve to an outlet connector 44 which forms an outlet 46 . The outlet port 44 is welded to the side wall of the pump housing 12 . A space (without reference number) located between the outlet valve 42 and the outlet socket 44 can be connected to the conveying space 34 via a pressure-limiting valve 48 .

The high-pressure fuel pump 10 is part of a fuel system, not shown, of an internal combustion engine. Fuel is delivered to the inlet 14 at relatively low pressure by a pre-supply pump. From the outlet 46, fuel is conveyed under relatively high pressure to a fuel rail, to which injectors are connected, which inject the fuel into the combustion chambers of the internal combustion engine. The fuel first reaches the pressure damper device 22 through the inlet 14 and from there via the inlet valve 32 to the pumping chamber 34 , where it is compressed to a high pressure and ejected via the outlet 46 . The direction of flow in the first fluid channel section 18 and in the second fluid channel section 20 is in figure 1 indicated by an arrow 49.

How out figure 1 As can be seen, a fuel filter device 50 is arranged in the first fluid channel section 18 . This is pot-shaped overall and includes an annular base portion 52, which is made of brass in the present case is produced and is held in the first fluid channel section 18 via a press fit, that is to say is pressed into the first fluid channel section 18 . From the annular base portion 52 as viewed in the axial direction of the annular base portion 52 and in figure 1 An approximately cylindrical or cup-shaped filter section 54 extends axially downward away from the damper chamber 24. The filter section 54 is made of PPS plastic in the present case. It comprises a total of three web sections 56 which protrude from the base section 52 in the axial direction of the base section 52 . A screen section 58 formed by a screen-like filter means is present between each two adjacent web sections 56 . In the figure 1 The lower protruding ends of the web sections 56 are connected to one another by an annular and upwardly closed cap-like end section 60, which is also made of PPS plastic. The end portion 60 is thus located remote from the base portion 52 . In an embodiment that is not shown, the filter device 50 could also be made entirely of plastic.

It can be seen from the representation in figure 1 that the filter section 54 extends as seen from the base section 52 approximately counter to the direction of flow (arrow 49) of the fuel. This means that the fuel passes through the sieve sections 58 from radially outside to radially inside and then flows out of the fuel filter device 50 axially upwards through the base section 52 .

Now, the fuel filter device 50 will be described in more detail with reference to FIG Figures 3 and 4 explained. A longitudinal axis of the fuel filter device 50 carries in figure 3 reference numeral 62. The base portion 52 has a larger outer diameter than the filter portion 54. The in figure 3 Visible sieve section 58 has two straight lateral longitudinal edges 64 that run parallel to the longitudinal axis 62, are spaced apart from one another by a distance a when viewed in the circumferential direction of the filter section 54. A first axial edge region 66 of the sieve section 58 is adjacent to the base section 52, and a second axial edge region 68 of the Screen section 58 is adjacent to end section 60 .

The first edge region 66 is concavely curved towards this center 70 , namely elliptically, viewed from a center 70 of the sieve section 58 located on an imaginary cylindrical lateral surface of the filter section 54 . In an embodiment that is not shown, the first edge area could also be parabolically or circularly curved. The second edge region 68 is also concave, viewed from the center 70 of the sieve section 58, towards this center 70, namely again elliptically curved. Again, in an embodiment that is not shown, the second edge area could also be parabolically or circularly curved. An extension of the first edge region 66 in the axial direction, i.e. in the direction of the longitudinal axis 62, is in figure 3 denoted by l ₆₆ , an extension of the second edge region 68 in the axial direction, ie also in the direction of the longitudinal axis 62, is denoted by l ₆₈ . You can tell figure 3 that the length l ₆₆ of the curved first edge area 66 is greater than the length l ₆₈ of the curved second edge area 68.

Due to the curved edge areas 66 and 68, the web sections 56 adjacent to these edge areas 66 and 68 each have a widened area which figure 3 is drawn hatched as an example for the lower web section 56 visible there and which bears the reference number 72 there. How out figure 3 , but in particular figure 4 As can be seen, lateral transitional areas 74 between the web sections 56 and the end section 60 and between the web sections 56 and the base section 52 are designed to be concavely rounded, as seen from the radial outside. Likewise, lateral transitional areas 76, with which the web sections 56 run into a conical transitional area 78, which is present between the filter section 54 and the base section 52, are concavely rounded off, as seen from the radial outside.

Particularly advantageous are the in figure 3 shown fuel filter device 50 following dimensions. A developed length of the sieve section 58 in the circumferential direction between two adjacent web sections 56 is designated as a. b denotes a circumferential width of a land portion 56 (in an embodiment where one land portion has a different width than another land portion, b denotes the width of the circumferentially thinnest land portion). With I becomes one Total length of a screen section 58 measured in the longitudinal direction 62 denotes.

The course of the first edge region 66 can follow an ellipse, the extent of which is between 0.1 and 1 times l, seen in the longitudinal direction 62 of the fuel filter device 50, and the extent of which in the circumferential direction is between 0.1 and 0.5 times a. Furthermore, the course of the first edge area 66 can follow a radius with a radius dimension in the range of 0.1-0.5 times a. The first edge region 66 can be rounded towards the web sections 56 and towards the base section 52 either by a radius in the range of 0.1-0.5 times a or by an ellipse whose main or secondary vertex is smaller than a.

The dimensioning rules mentioned above for the first edge area 66 can also be applied to the second edge area 68 in the same way.

It applies to the lateral transition areas 74 and 76 that their rounding can be in the range of 0.1-0.5 times a when using a radius. When using an elliptical curve, the major or minor vertex can be no more than 0.5 times a. Further rounding of edges of the web sections 56 can be carried out in the same way.

Now onto the in figure 5 shown embodiment of a fuel filter device 50 according to the invention. In this case, those elements and areas which have equivalent functions to elements and areas of the first embodiment bear the same reference symbols. They will not be explained again in detail below.

You can tell figure 5 that in the embodiment according to the invention shown there, the sieve sections 58 are not curved outwards in the normal position (in figure 5 shown in dashed lines), but as straight, even and flat sieve sections 58 are formed. As a result, a filter section 54 is formed, which is a total of polygonal, in the embodiment of figure 5 has triangular cross section.

Claims (2)

1. Fuel filter device (50) having an annular base section (52) and having an altogether cylindrical filter section (54) which extends from said base section, wherein the filter section (54) has a plurality of web sections (56) which extend from the base section (52) in a longitudinal direction (62), has in each case a screen section (58) between two adjacent web sections (56), and has an end section (60) which is arranged at a distance from the base section (52) as seen in the longitudinal direction (62), characterized in that the screen section (58) is altogether substantially planar, so that the filter section (54) has an altogether polygonal cross section.
2. High-pressure fuel pump (10) having a pump casing (12), having an inlet (14) and having a fuel filter device (50) according to Claim 1.

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