WO2018177753A1 - High-pressure fuel pump - Google Patents

Abstract

A high-pressure fuel pump (10) comprises a pump housing (12), an inlet (14), a fuel filter device (50), a pumping section (38), and an outlet (46). The fuel filter device (50) has an annular base portion (52) and an overall at least approximately cylindrical filter portion (54) extending from the base portion (52). According to the invention, the filter device (50) is arranged in such a way that the fuel flows into the annular base portion (52) in the axial direction and flows out of the filter portion (54) at least also in the radially outward direction.

Description

 description

title

 High-pressure fuel pump prior art

The invention relates to a high-pressure fuel pump according to the preamble of claim 1. 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, according to the delivery section comprises a pump piston. Although a fuel filter device is not explicitly mentioned in DE 10 2014 225 319 A1, such is usually present to be present in the fuel

 Keep impurities away from sensitive areas of the fuel high-pressure pump. Usually, the filter device is designed in the manner of a cylindrical pot, wherein the filter section is flowed through from the outside to the inside and the fuel through the annular base portion of the

Filter device flows out.

Disclosure of the invention

The problem underlying the invention is achieved by a high-pressure fuel pump with the features of claim 1. advantageous

Further developments of the invention are specified in subclaims. For the invention important features can also be found in the following description and in the drawing. The features disclosed therein can be important for the invention both alone and in completely different combinations, without being explicitly referred to again. The inventive arrangement of the filter device such that it is arranged between inlet and pressure damper that the fuel flows axially into the annular base portion and at least also flows radially outward from the filter section, the filter section is no longer from the outside to the inside by the fuel but flows through from the inside out. Thus, the risk that, for example, in the area of

Filter section existing webs bend because of the existing pressure gradient, reduced. Overall, this is the life of the

Filter device improved and / or allows a larger flow rate. Furthermore, it is prevented that the filter section, in particular when it is loaded with dirt or other contaminants, at least partially bulges inward and thus forms a throttling constriction or even collapses inwards. This in turn reduces the risk of vapor bubbles forming at higher flow rates.

It is understood that the term "radially" is to be understood very broadly and in no way refers to a flow directed only at an angle of 90 ° to a longitudinal axis of the fluid channel and / or the filter device " leave. It is also to be understood that the term "cylindrical" is to be understood very broadly and in no way designates a filter section which basically has an axially straight section and a circular cross section.Very different cross sections of the filter section are present under the term "cylindrical", for example triangular or polygonal or elliptical Cross sections, and in the axial direction variable cross sections or those that are conical or at least partially conical.

A first advantageous embodiment provides that the annular

Base portion is pressed into a fluid channel. This is a simple and inexpensive way of fixing.

It is also proposed that the filter device is arranged in a fluid channel, which opens directly into a damper chamber, in which a pressure damper is arranged. Such a damper chamber is easily accessible from the outside, so that the fluid channel opening into the damper chamber is also good is accessible. Thus, the filter device can be easily inserted into the fluid channel. In comparison to an arrangement of the filter device, for example in an inlet connection, this further reduces the risk of icing. If the filter device were arranged in the inlet nozzle, its temperature would sometimes reach its very low temperature

Adjust ambient temperatures, which may result in such icing.

It is particularly advantageous if the fluid channel widens toward the damper chamber. This achieves the following two advantages in particular:

This creates space for an assembly tool, for example a press-in tool, for mounting the filter device in the fluid channel. On the other hand, this increases the volume of the damper chamber, whereby the pulsation behavior of the high-pressure fuel pump in their

Low pressure range is improved, without the

 Overall dimensions of the fuel high-pressure pump are larger or a costly to produce recess in a damper chamber

limiting wall is required. This is achieved simply by the fact that the extended area of the fluid channel is directly connected to the damper space. Advantageously, the extension of the fluid channel to the damper chamber is dimensioned so that the strength of a housing portion in which the fluid channel is present (even) is not unduly reduced.

One possibility for such an extension is that the fluid channel is step-shaped. This is very easy to produce by machine.

With regard to the production of the fluid channel, it is possible for it to be produced by drilling, milling, a chemical removal method, or by a generative production method, in particular a 3-D printing method. Especially by milling, a chemical removal process or a generative

Manufacturing processes, any axial profiles and cross-sectional shapes of the fluid channel, in particular the extended area, can be realized.

As a result, the flow behavior can be optimized so that

Throttle losses can be reduced. This is especially true if the fluid channel at least partially has a non-circular cross-section or a non-cylindrical shape.

It is also proposed that the annular base portion of the fuel filter device is made of metal, in particular of brass. This is relatively inexpensive and offers particular advantages when the filter device is pressed into the fluid channel.

It is also possible that the filter device is at least partially made of plastic. It is conceivable, for example, that the entire

Filter device is made as a plastic injection molded part, or that the filter device is made as a multi-component injection molded part with a base portion made of metal and a filter section made of plastic. This also leads to cost advantages.

Hereinafter, an embodiment of the invention will be explained with reference to the accompanying drawings. In the drawing show:

FIG. 1 shows a first longitudinal section through a high-pressure fuel pump according to the invention; and

2 shows a second longitudinal section through the high-pressure fuel pump of

 Figure 1 along a line II-II.

A high-pressure fuel pump carries in Figures 1 and 2 in total the reference numeral 10. It comprises a pump housing 12, which in the

Has substantially cylindrical or rotationally symmetrical shape. In a side wall of the pump housing 12, as can be seen in FIG. 1, an inlet 14 is formed by an inlet connection 16, which is welded to the pump housing 12. From the inlet 14 extends in the pump housing 12, a first fluid channel section 18 in the radial direction inwards. It goes over into a second fluid channel section 20, which extends in the axial direction in the pump housing 12 up to a pressure damper device 22. This is a diaphragm damper, which will not be further described here. The pressure damper device 22 is accommodated in a damper chamber 24, which between an upper end face 26 of the pump housing 12 and one on the Pump housing 12 welded housing cover 28 is formed. The fluid channel section 20 opens into the damper chamber 24.

As can be seen from FIG. 2, a third fluid channel section 30 extends from the upper end side 26, that is to say away from the damper space 24, up to one

 Inlet valve 32, which is designed as a quantity control valve. This means that the inlet valve 32 can be forcibly held in an open position in a manner not described here in detail. In principle, the inlet valve 32 is designed as a check valve, which opens to a delivery chamber 34. The delivery chamber 34 is essentially limited by a

Wall of an axially in the pump housing 12 extending blind bore (without reference numeral) and a pump piston 36. The pump piston 36 is guided in a piston sleeve (without reference numerals) in the sliding seat and in the axial direction movable. The delivery chamber 34 and the pump piston 36 together form a delivery section 38.

From the delivery chamber 34, a fourth fluid channel section 40 branches off in the radial direction, which leads via an outlet valve 42 designed as a check valve to an outlet connection 44, which forms an outlet 46. The outlet port 44 is welded to the side wall of the pump housing 12. A between the exhaust valve 42 and the outlet port 44 located space (without reference numeral) is connected via a pressure relief valve 48 with the delivery chamber 34. The high pressure fuel pump 10 is part of a not shown

Fuel system of an internal combustion engine. To the inlet 14, fuel is delivered at a relatively low pressure by a prefeed 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 combustion chambers of the internal combustion engine. The fuel passes through the inlet

14 first to the pressure damper device 22 and from there via the inlet valve 32 to the delivery chamber 34, where it is compressed to a high pressure and discharged via the outlet 46. The flow direction in the first

Fluid channel section 18 and in the second fluid channel section 20 is indicated in Figure 1 by an arrow 49. As can be seen from FIG. 1, a fuel filter device 50 is arranged in the first fluid channel section 18. This is a total pot-shaped and comprises an annular base portion 52 which is made in this case made of brass and which is held via a press fit in the first fluid channel section 18, that is pressed into the first fluid channel section 18. Of the annular base portion 52 extends in the axial direction of the

seen in Figure 1 axially upwards to the damper chamber 24 through an approximately cylindrical or cup-shaped filter section 54. The filter section 54 is in the present case made of PPS plastic. It comprises a total of three webs 56, which protrude in the axial direction of the base portion 52 from the base portion 52. Between two adjacent webs 56 is in each case a flat, so in itself not curved sieve-like filter means 58 is present. The upper projecting ends of the webs 56 in FIG. 3 are connected to one another by an annular cap which is closed at the top and which is likewise made of PPS plastic. In one embodiment, not shown, the filter device 50 could also be made entirely of plastic. In a further embodiment, not shown, the cap 60 could not be closed but also a sieve-like filter means should be designed to be comprehensive.

It can be seen from the illustration in FIG. 1 that the filter section 54, viewed from the base section 52, extends approximately in the direction of flow (arrows 49) of the fuel. This means that according to the lower arrow 49 in FIG. 1, the fuel flows axially into the annular base section 52 and flows out radially (for example in FIG. 1 obliquely upward) out of the filter section 54 in accordance with the upper arrow 49 in FIG.

As can also be seen from FIG. 1, the second fluid channel section 20 widens toward the damper chamber 24. This is realized in the embodiment shown in that the fluid channel section 20 is stepped as a

Stepped bore is executed with a in Figure 1 upper and immediately opening into the damper chamber 24 section 62 with a larger diameter and a lower in Figure 1 and directly connected to the first fluid channel section 18 section 64 with a smaller diameter. In the present case, the second fluid channel section 20 is produced by drilling.

In principle, however, is also conceivable in a not shown

Embodiments that the second fluid channel section 20 by milling, by a chemical removal method, or by a generative

Manufacturing process, in particular a 3-D printing process is produced. In such a generative manufacturing method, the pump housing 12 would be advantageously produced by such a method. In particular, the abovementioned chemical removal method and the aforementioned generative production method have the advantage that, as a result, such fluid channels or fluid channel sections (in this case in particular the second fluid channel section 20) can also be produced, which have a non-circular cross-section in some areas.

Claims

claims 1 . A high-pressure fuel pump (10) having a pump housing (12), an inlet (14), a fuel filter device (50), a delivery section (38) and an outlet (46), wherein the fuel filter device (50) has an annular Base section (52) and a from this  extending total at least approximately cylindrical filter section (54), characterized in that the filter means (50) is arranged so that the fuel flows axially into the annular base portion (52) and at least also radially outwardly from the filter section (54) flows out , 2. High-pressure fuel pump (10) according to claim 1, characterized in that the annular base portion (52) is pressed into a fluid channel (20). 3. High-pressure fuel pump (20) according to one of the preceding  Claims, characterized in that the filter device (50) in a fluid passage (20) is arranged, which opens into a damper chamber (24) in which a pressure damper device (22) is arranged. 4. High-pressure fuel pump (20) according to claim 3, characterized in that the fluid channel (20) widens towards the damper chamber (24). 5. High-pressure fuel pump (10) according to claim 4, characterized in that the fluid channel (20) is step-shaped. 6. High-pressure fuel pump (10) according to one of claims 4 or 5,  characterized in that the fluid channel (20) by drilling, milling, a chemical removal method, or by a generative Manufacturing process, in particular a 3-D printing process is produced. 7. High-pressure fuel pump according to one of claims 2-6, characterized in that the fluid channel at least partially has a non-circular cross-section. 8. High-pressure fuel pump (10) according to one of the preceding  Claims, characterized in that the annular base portion (52) of the fuel filter device (50) made of metal, in particular made of brass. 9. High-pressure fuel pump (10) according to any one of claims 1 -6, characterized in that the filter device (50) is at least partially made of plastic.