GB2577731A

GB2577731A - A fuel filter

Info

Publication number: GB2577731A
Application number: GB1816222.2A
Authority: GB
Inventors: Foord Gary; p Enoch Cynthia
Original assignee: Delphi Technologies IP Ltd
Current assignee: Delphi Technologies IP Ltd
Priority date: 2018-10-04
Filing date: 2018-10-04
Publication date: 2020-04-08
Anticipated expiration: 2038-10-04
Also published as: GB2577731B

Abstract

A fuel pump 1 of an injection equipment of an internal combustion engine, comprising a body 4 and a head cap 5 which define an inlet chamber 21, a filter (20, Fig. 3) is located in the inlet chamber 21 and is arranged so that a first end 35 of the filter engages an upper surface of the body 4, and a second end 36 of the filter engages a lower surface of the cap 5, the filter has a frame 34 which comprises windows 30 which support a filtration mesh (33, Fig. 3) through which fuel passes in use, the windows 30 have a periphery which defines a continuous surface (32, Fig. 3) which is configured so that, in use, when low pressure fuel passes through the windows 30, a net force is created which acts on the continuous surface (32, Fig. 3) and causes the filter (20, Fig. 3) to be pushed in the direction of the body 4 of the pump 1 to improve the integrity of the seal between the filter and the pump body 4.

Description

A FUEL FILTER

TECHNICAL FIELD

The present disclosure relates to a fuel pump of an injection equipment of an internal combustion engine. In particular, but not exclusively, to a diesel fuel pump for use in a high pressure diesel fuel system. Aspects of the disclosure also relate to a fuel system.

BACKGROUND

High pressure supply pumps for diesel fuel systems are well known. Such pumps supply fuel from a fuel storage tank to the diesel fuel system via a high pressure pump outlet.

It is standard practice to filter the fuel before it enters the pump chamber of the fuel pump assembly to ensure that any particulate contaminants are removed which might otherwise damage the pump or other downstream components. It is vital to ensure that there are no leak paths past the filter via which fuel can bypass the filtration mesh and allow potentially damaging particulate contaminants into the pump and on to other downstream components.

SUMMARY OF THE INVENTION

The present invention provides a fuel pump of an injection equipment of an internal combustion engine, the pump having a body and a head cap defining an inlet chamber therebetween, the pump further comprising a filter located within the inlet chamber, the filter having a first end and a second end, wherein the filter is arranged within the inlet chamber so that the first end engages an upper surface of the body, and the second end engages a lower surface of the cap, wherein the filter comprises a frame having one or more windows through which fuel may pass in use, wherein the or each window supports a filtration mesh, and wherein the or each window has a periphery which defines a continuous surface, wherein the continuous surface is configured so that, in use, when low pressure fuel passes through the one or more windows a net force is created which acts on the continuous surface of the one or more windows and causes the filter to be pushed in the direction of the upper surface of the body, thereby improving the integrity of the seal between the first end of the filter and the upper surface of the body.

Optionally, the frame may comprise two or more windows of substantially the same size. Such an arrangement is beneficial for ease of manufacture and for more uniform fuel flow characteristics in use.

The filter is optionally substantially tubular in form for ease of manufacture and conformity with the fuel pump.

In an optional embodiment, the frame may comprise a plurality of legs, wherein each leg is located between adjacent windows. The legs assist in transferring load from the second end of the filter to the first end.

Optionally, each leg may taper from the second end of the filter to the first end of the filter. Such an arrangement beneficially provides a greater distribution of surface area on the window periphery towards the first end of the filter. The taper of each leg is optionally about 101 from a line parallel with an axis of the filter. The taper may be varied to adjust the size of the window and total filtration area for the filter as desired.

In an optional embodiment, a portion of the first surface of the one or more windows is substantially parallel to a portion of the second surface of the one or more windows. This is beneficial for ease of manufacture of the filter. Optionally, the one or more windows may be substantially trapezoidal.

The filter optionally comprises at least one seat for engagement with a sealing surface of the body to beneficially improve the sealing between the filter and the body.

In an optional embodiment, the frame may comprise at least one profile which is configured to receive an 0-ring. Such a profile assists in keeping the 0-ring in place in use and during assembly.

Optionally, the filtration mesh may be integrally formed with the frame to improve manufacture time and cost.

The frame may optionally comprise nylon. In an optional embodiment, the nylon material of the frame may be a stronger grade than the nylon material of the filtration mesh. Such an arrangement reduces cost while maintaining the structural integrity of the frame.

In another aspect, the present invention provides a fuel supply system comprising a fuel pump as described above.

Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and/or features of any embodiment can be combined in any way and/or combination, unless such features are incompatible.

BRIEF DESCRIPTION OF THE DRAWINGS

One or more embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a cross-sectional view of a portion of a diesel fuel pump according to the invention; Figure 2 is a partial cut-away isometric view of the diesel fuel pump of Figure 1; and Figure 3 is an isometric view of the filter of Figure 2.

DETAILED DESCRIPTION

Figure 1 shows a cross-sectional view of a diesel pump assembly 1 comprising a hydraulic head body 4 and a hydraulic head cap 5. The hydraulic head body 4 defines a compression chamber 8 and a pump outlet 6. A fuel filter 20 is located in an inlet chamber 21 defined by the hydraulic head cap 5 and the hydraulic head body 4. Fuel flows into the inlet chamber 21 via an inlet chamber passage 2 (shown by dashed lines as it is not in section plane). An 0-ring seal 3 is provided between the hydraulic head body 4 and the hydraulic head cap 5 to seal the inlet chamber 21 and prevent leakage.

The fuel pump assembly 1 further comprises a compression chamber inlet valve 7 to allow low pressure fuel into the compression chamber 8 via compression chamber inlet passage 15. In use, an outlet valve (not shown) is located within the pump outlet 6 to allow high pressure fuel to leave the pump assembly 1 once it has been pressurised. In operation, the fuel is pressurised in the compression chamber 8 by a plunger 9 which reciprocates in a plunger bore 10 provided in the hydraulic head body 4. The plunger 9 may, for example, be driven by a cam (not shown).

The compression chamber inlet valve 7 comprises an inlet valve body 12 having a chamfered surface 13 which is arranged to seal against valve seat 14 formed within the compression chamber 8. The inlet valve body 12 is biased by a compression spring 16 in the closed position such that the chamfered surface 13 of the inlet valve body 12 is pushed against the valve seat 14.

At the start of the fuel pumping cycle, the inlet valve 7 is opened on the downward movement of the plunger 9, the outlet valve (not shown) is closed and low pressure fuel is drawn into the compression chamber 8 via compression chamber passage 15, filling the compression chamber 8 with fuel. As the plunger 9 then moves upwards (driven, for example, by a cam), the inlet valve 7 closes under the action of the compression spring 16, the fuel in the compression chamber 8 is compressed, and the pressure of the fuel increases. The outlet valve (not shown) then opens and pressurised fuel flows out of the compression chamber 8, leaving the pump 1 via pump outlet 6.

As the pressurised fuel flows out of the compression chamber 8 the pressure in the compression chamber 8 drops and the outlet valve (not shown) closes, ending the fuel pumping cycle. The plunger driving mechanism (not shown) is arranged to then repeat the plunger 9 movement again, ready to start the next pumping cycle.

Figure 2 shows a partial cut-away view of the diesel fuel pump assembly of Figure 1. The fuel filter 20 is located within an inlet chamber 21 formed between the hydraulic head body 4 and the hydraulic head cap 5. A fuel inlet (not shown) supplies low pressure fuel to the inlet chamber 21 from a fuel tank (not shown). The filter 20 is substantially tubular in form with a longitudinal axis L. The filter 20 extends between the lowermost surface 41 of the hydraulic head cap 5 and an upper surface 26 of the hydraulic head body 4.

The filter 20 has a first end 35 and a second end 36. In use, the first end 35 of the filter is located proximate the upper surface 26 of the hydraulic head body 4, and the second end 36 is located proximate the lowermost surface 41 of the hydraulic head cap 5. The filter comprises a nylon frame 34 which has four windows 30 of equal size evenly spaced around the periphery of the frame 34. Legs 37 extend between the first end 35 and the second end 36 of the filter 20. The legs 37 taper from the second end 36 of the filter 20 to the first end 35 of the filter 20 at an angle of about 10-Ito an imaginary line which is parallel to the longitudinal axis L' of the filter 20. The end of the frame 34 which forms the second end 36 of the filter 20 has a profile 23 for receiving a rubber 0-ring seal 22.

As shown in Figure 2, the cross-sectional width of the frame 34 tapers from the legs 37 to a rounded end surface 25. In use the rounded end surface 25 engages with the upper surface 26 of the hydraulic pump head 4, which surface 26 generally conforms to the shape of the rounded end surface 25. This configuration helps to ensure a good contact and seal between the filter 20 and the hydraulic pump head 4 in use.

The periphery 31 of the windows 30 comprise a continuous surface 32. In this embodiment the windows 30 have a generally trapezoidal shape wherein a first surface 42 of the windows 30 are substantially parallel and opposite to a second surfaces 43 of the windows 30.

Although not shown in Figure 2 for the sake of clarity, it can be seen in Figure 3 that the windows 30 comprise a mesh 33 which extends across the windows 30. In this embodiment, the mesh 33 is a nylon mesh which is integrally formed with the frame 34.

In this embodiment, the nylon material of the frame 34 is of a higher and stronger grade than the nylon material of the mesh 33. However, in other embodiments, the nylon material of the frame 34 and mesh 33 may be the same. It is preferred that the mesh 33 be located generally in radial alignment with an inner surface 39 of the frame 34. However, this is not essential and the mesh 33 could be located at any depth throughout the window periphery 31, or could be generally in radial alignment with the outer surface 38 of the frame 34.

In use, low pressure fuel is supplied from a fuel tank (not shown) to an inlet (not shown) of the inlet chamber 21. As the high pressure pump assembly 1 operates, fuel passes through the mesh 33 of the windows 30 before passing into the compression chamber 8 via compression chamber inlet valve 7. In this way, any particulate contaminants are removed from the fuel before it reaches the high pressure side of the pump assembly 1, or any other downstream component.

As can be seen most clearly in Figure 2, in use, the second end 36 of the filter 20 seals against the lowermost surface of the hydraulic head cap 5 by virtue of the rubber 0-ring seal 22. When installed, the rubber 0-ring seal 22 is compressed between the hydraulic head cap 5 and the filter frame 34. This in turn causes the first end 35 of the filter 20 to exert a force on the upper surface 26 of the hydraulic head body 4 to form a seal.

The seal between the first end 35 of the filter 20 and the upper surface 26 of the hydraulic head body 4 is further improved in use by virtue of the action of the low pressure fuel on the continuous surface 32 of the windows 30. In view of the fact that the first surfaces 42 of the windows 30 have a greater surface area than the second surfaces 43 of the windows 30, and considering the overall distribution of forces on the continuous surfaces 32 around the window 30, an increased net force is created which causes the filter 20 to be pushed in the direction of the hydraulic head body 4, thus improving the integrity of the seal between the rounded end surface 25 of the filter 20 and the upper surface 26 of the hydraulic head body 4.

It will be appreciated that the action of pushing the filter 20 towards the hydraulic head body 4 will reduce the sealing effect of the 0-ring seal 22 between the second end 36 of the filter 20 and the hydraulic head cap 5. Such an effect may be countered by ensuring that the 0-ring seal 22 is sufficiently sized and specified so that the seal between the second end 36 of the filter 20 and the hydraulic head cap 5 maintains its integrity in use.

As will be apparent to a person skilled in the art, the above described embodiment is an example only and there are many modifications which may be made without departing from the scope of the invention. A number of modifications are discussed below. However, the skilled person will appreciate that other modifications will be possible and the discussion below is not intended to present an exhaustive discussion of all possibilities.

The windows 30 may be of any suitable shape provided that the combined surface area of the windows is such that, in use, the net force created by the action of the low pressure fuel on the window surfaces causes the filter 20 to be pushed further towards the hydraulic head body 4. For example, the windows 30 may have a curvilinear form or may be of any suitable geometric shape such as square, rectangular or triangular.

It is not necessary that all of the windows have the same size, shape and form provided that in use, the net force created by the action of the low pressure fuel on the widow surfaces causes the filter 20 to be pushed further towards the hydraulic head body 4.

For example, the windows may comprise a series of tessellating triangles where the number of triangles with their bases proximate the first end 35 of the filter 20 exceeds the number of triangles with their bases proximate the second end 36 of the filter 20. Alternatively, the windows may comprise a series of rectangles in orthogonal orientations to one another.

In one embodiment the filter 20 may comprise only one window 30.

In the examples discussed above with reference to Figures 1 to 3, the filter has a substantially cylindrical shape. However, the filter 20 may have any suitable cross-sectional shape such as square, rectangular or any non-standard geometric shape with or without symmetry.

The frame material may comprise any suitable material such as steel, aluminium or plastic. The mesh may comprise a different material to the frame.

In one embodiment, the seal 22 at the second end of the filter 20 is integrally formed with the frame 34.

The continuous surfaces 32 forming the periphery of the one or more windows 30 may be substantially planar and orthogonal to the outermost surface 38 of the filter 20.

Alternatively the surfaces may be convex or concave, or a combination thereof, or they may slope inwardly towards the inner surface 39 of the filter or the outer surface 38 of the filter.

LIST OF REFERENCES

1 diesel pump assembly 2 inlet chamber passage 3 pump 0-ring seal 4 hydraulic head body hydraulic head cap 6 pump outlet 7 compression chamber inlet valve 8 compression chamber 9 plunger plunger bore 12 inlet valve body 13 chamfered surface on inlet valve body 14 inlet valve seat 15 compression chamber inlet passage 16 compression spring fuel filter 21 inlet chamber 22 filter 0-ring seal 23 seal profile rounded end surface 26 hydraulic head body upper surface window 31 window periphery 32 continuous surface 33 filter mesh 34 frame first end of filter 36 second end of filter 37 legs 38 outer surface of filter 39 inner surface of filter 41 hydraulic head cap lowermost surface 42 first window surface 43 second window surface

Claims

CLAIMS1. A fuel pump (1) of an injection equipment of an internal combustion engine, the pump having a body (4) and a head cap (5) defining an inlet chamber (21) therebetween, the pump (1) further comprising a filter (20) located within the inlet chamber (21), the filter (20) having a first end (35) and a second end (36), wherein the filter (20) is arranged within the inlet chamber (21) so that the first end (35) engages an upper surface (26) of the body (4), and the second end (36) engages a lower surface (41) of the cap (5), wherein the filter (20) comprises a frame (34) having one or more windows (30) through which fuel may pass in use, wherein the or each window (30) supports a filtration mesh (33), and wherein the or each window (30) has a periphery (31) which defines a continuous surface (32), wherein the continuous surface (32) is configured so that, in use, when low pressure fuel passes through the one or more windows (30) a net force is created which acts on the continuous surface (32) of the one or more windows (30) and causes the filter (20) to be pushed in the direction of the upper surface (26) of the body (4), thereby improving the integrity of the seal between the first end (35) of the filter (20) and the upper surface (26) of the body (4).
2. A fuel pump (1) according to claim 1, wherein the frame (34) comprises two or more windows (30) of substantially the same size.
3. A fuel pump (1) according to claim 2, wherein the filter (20) is substantially tubular in form.
4. A fuel pump (1) according to claim 3, wherein the frame (34) comprises a plurality of legs (37), wherein each leg (37) is located between adjacent windows (30).
5. A fuel pump (1) according to claim 4, wherein each leg tapers from the second end (36) of the filter (20) to the first end (35) of the filter (20).
6. A fuel pump (1) according to claim 5, wherein the taper of each leg is about 101 from a line parallel with an axis of the filter (20).
7. A fuel pump (1) according to any preceding claim, wherein a portion of the first surface (42) of the one or more windows (30) is substantially parallel to a portion of the second surface (43) of the one or more windows (30).
8. A fuel pump (1) according to any preceding claim, wherein the one or more windows (30) are substantially trapezoidal.
9. A fuel pump (1) according to any preceding claim, wherein the filter (20) comprises at least one seat (25) for engagement with a sealing surface (26) of the body (4)
10. A fuel pump (1) according to any preceding claim, wherein the frame (34) comprises at least one profile (23) which is configured to receive an 0-ring (22).
11. A fuel pump (1) according to any preceding claim, wherein the filtration mesh (33) is integrally formed with the frame (34).
12. A fuel pump (1) according to any preceding claim, wherein the frame (20) comprises nylon.
13. A fuel pump (1) according to claim 12, wherein the nylon material of the frame (34) is a stronger grade than the nylon material of the filtration mesh (33).
14. A fuel supply system comprising a fuel pump (1) according to any preceding claim.