FUEL FILTER

Abstract

A fuel filter used with a supply of liquid fuel and with an engine has a housing formed with a filter chamber, with inlet and outlet ports respective connected to the supply and to the engine and opening into the chamber, and with a throughgoing return passage juxtaposed with the filter chamber and extending between a return-fuel inlet connected to the engine and a return-fuel outlet connected to the tank. A filter element is in the chamber between the inlet and outlet ports. Fuel moves in a circuit from the supply to the inlet port, thence through the filter element in the chamber, thence out the outlet port to the engine where a portion of the fuel is consumed and a portion of it is heated and flowed back to the return-fuel inlet, and thence through the passage and out the return-fuel outlet to the supply.

Claims

1. In combination with a supply of liquid fuel and with an engine, a fuel-filter housing formed with a filter chamber, an inlet port connected to the supply and opening into the chamber, an outlet port connected to the engine and opening into the chamber, and a throughgoing return passage juxtaposed with the filter chamber and extending between a return-fuel inlet connected to the engine and a return-fuel outlet connected to the tank, and a filter element in the chamber between the inlet and outlet ports; and pump means associated with the engine for moving the fuel from the supply to the inlet port, thence through the filter element in the chamber, thence out the outlet port to the engine where a portion of the fuel is consumed and a portion of it is heated and flowed back to the return-fuel inlet and thence through the passage and out the return-fuel outlet to the supply, whereby the heated fuel in the return passage heats the housing and the fuel therein.

2. The combination defined in claim 1, wherein the return passage has at least one opening directed toward a housing lower wall and through which rising gas enters the return passage, so that the gas can be discharged from the housing with the fuel flowing through the return passage.

3. The combination defined in claim 2, wherein the return passage is open toward the housing lower wall over the majority of its length passing through the housing.

4. The combination defined in claim 2, wherein the housing is formed in the chamber with at least one flow groove angled to the opening of the return passage and open downward toward the housing lower wall.

5. The combination defined in claim 4, wherein the return passage with the return-fuel inlet and return-fuel outlet are juxtaposed with the inlet port, and, in a normal operating position of the apparatus, the return passage is above the inlet port.

6. The combination defined in claim 1, further comprising: a heater for heating the fuel introduced into the housing upstream of the inlet port of the housing.

7. The combination defined in claim 6, further comprising: control means for operating the heater only during a starting phase of the engine when same is cold.

8. The combination defined in claim 1, wherein the housing has a housing base and a housing cover detachably fixed on the housing base and forming the chamber with the cover, the return passage being in the housing cover with the return-fuel inlet and the return-fuel outlet.

9. The combination defined in claim 1, wherein the filter element has a separating screen for separating fluid components of greater density and the housing forms below the filter element at least one sump for catching or collecting the fluid components of greater density.

10. The combination defined in claim 9, wherein the filter element is tubularly cylindrical and defines a central passage of the housing that is substantially vertical in a normal operating position of the apparatus and that is formed of filter material that is formed with pleats extending vertically and parallel to a vertical longitudinal central axis of the housing.

11. The combination defined in claim 9, the separating screen surrounds the central passage of the housing and is surrounded by the filter element that is a tubular cylinder.

12. The combination defined in claim 9, wherein the pump means moves the fuel radially inwardly from the inlet port through the filter element to the central passage and thence up the central passage to the outlet port.

13. The combination defined in claim 12, wherein the return passage with the return-fuel inlet and the return-fuel outlet as well as the inlet port are upstream of the filter element and the central passage is downstream of the filter element.

14. The combination defined in claim 10, wherein the return passage is at an edge of the housing cover and is bordered on one side by a side wall of the housing cover.

15. The combination defined in claim 1, wherein the inlet port or the outlet port is on the same side of the housing or housing cover as the return passage.

16. The combination defined in claim 2, wherein the opening of the return passage opens into the chamber between the inlet port and the fuel element.

17. In combination with a supply of liquid fuel and with an engine, a fuel-filter housing formed with a filter chamber, an inlet port connected to the supply and opening into the chamber, an outlet port connected to the engine and opening into the chamber, a throughgoing return passage juxtaposed with the filter chamber and extending between a return-fuel inlet connected to the engine and a return-fuel outlet connected to the tank, and a sump below the chamber; a filter element in the chamber between the inlet and outlet ports and subdividing the chamber into an upstream inflow compartment into which the inlet port opens and a downstream outflow compartment into which the outlet port opens, the filter element being adapted to separate solid particles, gas, and dense liquid from the fuel, the return passage having an opening into the inflow compartment; and pump means associated with the engine for moving a stream of the fuel from the supply to the inlet port, thence through the filter element in the chamber, thence out the outlet port to the engine where a portion of the stream of fuel is consumed and a portion of it is heated and flowed back to the return-fuel inlet and thence through the passage and out the return-fuel outlet to the supply, whereby the heated fuel in the return passage heats the housing and the fuel therein while dense liquid in the fuel settles into the sump and gas in the fuel rises up to the return passage and is carried off by the fuel therein.

Description

BRIEF DESCRIPTION OF THE DRAWING

[0029] The above and other objects, features, and advantages will become more readily apparent from the following description, reference being made to the accompanying drawing in which:

[0030] FIG. 1 is a perspective view of an apparatus according to the invention;

[0031] FIG. 1A is a perspective view of the filter element of this invention;

[0032] FIG. 2 is a section through the apparatus of FIG. 1;

[0033] FIG. 3 is a section through the housing cover of the apparatus according to the invention; and

[0034] FIG. 4 is a bottom view of the housing cover of the apparatus according to the invention.

SPECIFIC DESCRIPTION OF THE INVENTION

[0035] FIG. 1 shows an apparatus according to the invention for cleaning a fluid medium, here diesel fuel. With this apparatus, solid particles and fluid components of greater density can be separated from fluid components of lesser density.

[0036] The apparatus has a housing 1 with an inlet port 2 for the fluid medium to be cleaned (diesel fuel) and an outlet port 3 for the cleaned fluid medium (cleaned diesel fuel). According to the invention, a return passage 4 for the fluid medium returned from a consumer, here an engine M, is provided with a return-fuel inlet 5 and a return-fuel outlet 6, with the return passage 4 passing through the housing 1.

[0037] FIG. 1 shows a highly simplified view of the preferred functionality of an apparatus according to the invention. Diesel fuel to be cleaned is drawn by a pump 26 from a tank T to the apparatus according to the invention and there enters the housing 1 through the inlet port 2. After cleaning in the apparatus, the diesel fuel moves again out of the outlet port 3 and to the engine M. Diesel fuel not used by the engine M is then returned to the tank T according to the invention via the return passage 4 of the apparatus according to the invention. The returned diesel fuel coming from the engine is introduced through the return-fuel inlet 5 into the housing 1, flows through the return passage 4, and passes out of the housing 1 again through the return-fuel outlet 6 to the tank T.

[0038] Here the housing 1 preferably has a lower housing base 12 with a lower wall 7 as well as a cover 13 fixed on the housing base 12. Preferably and here the housing base 12 and housing cover 13 are detachably interconnected, with a screw connection 20 being recommended used for this purpose, as in the illustrated embodiment.

[0039] It lies within the scope of the invention if the return passage 4 has an opening 8 directed toward the housing lower wall 7 of the housing 1. Preferably and here the return passage 4 is open toward the housing lower wall 7 over the majority of its length 1 passing through the cover 13 of the housing 1. The result is that the opening 8 is long and continuous. the opening 8 is open toward the housing lower wall 7 over more than 40% of the circumference of the return passage 4. and the return passage 4 has a round or circular cross section. The downwardly directed opening 8 of the return passage 4 ensures that gas, particularly air, emerging from the fluid medium, more particularly from the diesel fuel, rises in the housing 1 and collects in the opening 8 and/or in the return passage 4. The fluid medium (diesel fuel) returned via the return passage 4 can carry this gas, more particularly this air, along and discharge it from the housing 1 via the return-fuel outlet 6. Objectionable accumulations of gas, more particularly of air, in the housing 1 can thus be prevented in an advantageous manner. Once in the tank, the entrained air can be vented or fed to the engine intake manifold.

[0040] According to a preferred embodiment and here two flow grooves 9 angled upward and inward toward the opening 8 of the return passage 4 are provided to conduct the gas flow toward the return passage 4 and to conduct the accumulation of gas into the return passage 4 (FIG. 4). Preferably and here these flow grooves 9 are provided on or in the lower face of the cover 21 of the container cover 13. These flow grooves 9 are angled continuously toward the return passage 4 and preferably and here toward the center of the return passage 4. The upper wall of the return passage 4, which, both is on the bottom face 21 of the cover of the container cover 13, forms the highest point and/or the highest level relative to the flow grooves 9 to which the gas, more particularly the air, flows upward through the flow grooves 9.

[0041] A filter subassembly 10 is provided in the housing 1 of the apparatus according to the invention. It has an overall tubularly cylindrical filter element 14 and a likewise tubularly cylindrical separating screen 15 mounted in it. Preferably and here the filter element 14 and the separating screen 15 surround and define a central passage 17 of the housing 1 and the filter element 14 and separating screen 15 are coaxial to the central passage 17 that itself runs parallel and coaxially to a longitudinal central axis L of the generally cylindrical housing 1.

[0042] The filter subassembly 10 in the housing 1 divides the chamber of the housing into an upstream inflow side 22 for the fluid medium to be cleaned (diesel fuel) and a downstream outflow side 23 for the cleaned fluid medium (diesel fuel). The fluid medium to be cleaned (diesel fuel) flows via the inlet port 2, which is in the housing cover 13, into the inflow side 22 that extends annularly around the filter subassembly 10. The fluid medium to be cleaned then flows radially inward through the filter element 14, with solid particles being separated from the fluid medium, and subsequently flows radially inward through the separating screen 14, with fluid components of greater density being separated from fluid components of lesser density. The components of greater density are particularly water. The components of greater density, more particularly the water, flows under the effect of gravity toward the housing lower wall 7 and collects in a sump 16 at the bottom of the housing. The central passage 17 oriented coaxially to the central longitudinal axis L of the housing 1 forms the outflow side 23 for the fluid medium cleaned in the filter subassembly 10. This cleaned fluid medium (diesel fuel) flows upward via the central passage 17 into a cylindrical outlet area 24 and exits it via the outlet port 3 of the housing.

[0043] The figures show that the return passage 4 according to the invention is oriented with its return-fuel inlet 5 and its return-fuel outlet 6 on the same side of flow, namely on the inflow side 22, as the inlet port 2 of the housing. The return passage 4 is provided with its return-fuel inlet 5 and its return-fuel outlet 6 outside the inlet port 2. Here the outlet port 3 is provided at the same level as the return passage 4, more particularly its return-fuel inlet 5, and its return-fuel outlet 6.

[0044] It was already pointed out above that, according to a preferred embodiment of the invention, diesel fuel not used up by the engine is introduced into the apparatus according to the invention via the return-fuel inlet 5 of the return passage 4. This is heated diesel fuel, so the interior of the housing, more particularly the diesel fuel inside the housing is warmed or heated. Unwanted precipitation or flocculation such as occurs particularly at lower temperatures can thus be prevented in a simple and effective manner from occurring in the housing 1. Thus the return passage 4 according to the invention performs two essential functions. For one, the fluid medium returned to the return passage 4 can be used to functionally and reliably remove from the housing 1 gas, more particularly air, that forms or accumulates in the housing. For another, the housing 1 can be heated by the fluid medium returned to the return passage 4 in order to prevent unwanted flocculation from occurring.

[0045] Furthermore, a preferred embodiment of the invention is characterized in that a heater 11 is provided upstream of the inlet port 2 to heat the fluid medium to be cleaned that is introduced into the housing 1. Preferably, this heater 11 operates above all or only when the engine M is started. During subsequent running, further heating of the fluid medium can occur by means of the hot fluid medium returned to the return passage 4.

[0046] The filter subassembly 10 has a filter element 14 for separating solid particles from the fluid medium. The filter material of the filter element 14 is pleated, and the pleats 18 of the filter material extend parallel to the longitudinal central axis L of the housing 1. By virtue of this orientation of the filter material, gas, particularly air, present in the housing 1 can easily flow upward through the paces between the pleats 18 of the filter material toward the return passage 4. Moreover, the filter material of the filter element 14 has coalescence characteristics and thus promotes the formation of droplets of the fluid components of greater density, particularly of water, to facilitate separation of these fluid components on the separating screen 15 and hence the collection of these components in the sump 16.

[0047] The filter subassembly 10 is also sealed off from the lower region of the housing 1, more particularly from the sump 16, by a seal 25 that is preferably embodied as an 0-ring. The figures show that, the return passage 4 according to the invention is at the edge of the housing 1, more particularly of the housing cover 13, and, preferably and here is bordered on one side by a side wall 19 of the housing 1 or of the housing cover 13. Advantageously, and here the inlet port 2 is also provided at this edge of the housing 1, it being preferred and provided for here as already noted, that the inlet port 2 is below the return passage 4.