FUEL FEEDER

Abstract: A fuel filter 10, constructing a supply unit 8, comprises a filter case 11 having an electric conductivity and a filter element 14. The filter case 11 is formed with an inside wall portion 11A and an outside wall portion 11B into a U shape in lateral cross section, so as to enlarge a contact area contacting with fuel in a fuel tank. The fuel discharged from the fuel pump 9 flows into a fluid chamber 15 of the fuel filter 10, and then be supplied from a fuel supply conduit 20 through a fuel flow passageway 12A to the outside. At this time, static electricity charged in the filter case 11 is discharged through its outer peripheral surface into the surrounding fuel having a slight electric conductivity.

Description: TECHNICAL FIELD The present invention relates to a fuel supply device which is provided within a fuel tank for example in an automotive vehicle, and can be suitably applied to supply fuel into the engine. BACKGROUND ART Generally, a fuel supply device consisting of a fuel tank in which fuel is stored, a fuel pump disposed in the fuel tank to discharge the fuel in the fuel tank to the exterior thereof, and a fuel filter provided in the fuel tank together with the fuel pump to purify the fuel discharged from the fuel pump, is well known. In this sort of conventional fuel supply device, in order to feed the fuel in the fuel tank within toward the engine, the fuel pump and the fuel filter are disposed in the fuel tank under a condition where the fuel pump and the fuel filter are integrally installed on a mounting bracket made of synthetic resin, and contacts the fuel, such as gasoline, stored in the fuel tank. During operation of the engine, the fuel within the fuel tank is discharged by means of the fuel pump, and flows through the fuel filter for purification, and then fed into the outside of the fuel tank toward each of fuel injection valves of the engine. On the other hand, the fuel filter is constructed by a filter case installed on the mounting bracket, and a filter element disposed in the filter case. A fuel flow passageway is defined between the filter case and the filter element. The fuel, discharged out of the fuel pump and entering into the fuel filter, is purified by way of the filter element, while flowing through the above-mentioned flow passageway. In the previously-noted prior art, the fuel, which is discharged from the fuel pump during operation of the engine, enters into the fuel filter, and passes through the filter element of fine mesh. Thus, there is a tendency turbulent flow to occur within the fuel filter, since the fuel flow is violently disturbed just before and after the filter element. As a result, static electricity builds up in the filter case of the fuel filter due to the filter case put into contact with the fuel. However, for the purpose of compactly disposing the filter case in the fuel tank, the filter case is installed on the mounting bracket made of synthetic resin together with the fuel pump, so that the filter case is kept in an electrically insulated state within the fuel tank. For the reasons set forth above, the prior art has a problem that the static electricity charged in the filter case due to friction between the filter case and the fuel is gradually stored and built up. EP 0754483 A1 discloses a fuel supply device of the type mentioned in the prior art portion of claim 1. A connection between the lower portion of the pump and the filter housing prevents a free-flow communication between the fuel in the tank and the inside wall portion of the filter case. It is an object of the invention to provide a fuel supply device, which is capable of relieving the static electricity to the exterior and preventing the static electricity from being stored in the filter case. This object is achieved by a fuel supply device in accordance with claim 1. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a system block diagram illustrating a conventional fuel supply device. Fig. 2 is a longitudinal cross sectional view taken along the line II - II shown in Fig. 3 and corresponding to an enlarged view of the supply unit of the fuel supply device. Fig. 3 is a plan view illustrating the supply unit of the fuel supply device of Fig. 2. Fig. 4 is a longitudinal cross sectional view taken along the line IV - IV shown in Fig. 5 which shows the fuel supply device according to the invention. Fig. 5 is a plan view illustrating the supply unit of the fuel supply device of Fig. 4. DESCRIPTION OF THE PREFERRED EMBODIMENTS In the drawings, Figs. 1 through 3 show a conventional fuell supply device. In this example, the fuel supply device is exemplified in a fuel supply device for an automobile engine. In the drawings, reference sign 1 denotes a fuel tank in which fuel, such as gasoline, is stored. A supply unit 8, which will be hereinafter described, is provided in the fuel tank for feeding the fuel in the tank within toward the engine 2. A lid plate 1A of the fuel tank 1 is formed with an opening 1B (see Fig. 3) for installing thereon a unit body 16 of the supply unit 8. On the other hand, commonly, the fuel within the fuel tank is mixed slightly with impurities having an electric conductivity, such as moisture, and thus such the fuel is conditioned in a conducting state. Particularly, the moisture tends to stay to some degree on the bottom portion 1C of the fuel tank 1, while the automotive vehicle is used for a long period of time. Reference sign 3 denotes a fuel line installed on the engine 2. The fuel line 3 is formed with fuel injection valves 4 , 4, ··· , for injecting fuel into the respective engine cylinders. The fuel line 3 is connected at it one end through a line 5 to the fuel supply portion 20 of the supply unit 8, and also connected at the other end through a pressure regulator 6 used for fuel pressure regulation and a return line 7 to a return conduit 21 of the supply unit 8. Reference sign 8 denotes the supply unit provided in the fuel tank 1. As seen in Fig. 2, the supply unit 8 is constructed by a fuel pump 9, a fuel filter 10, and the unit body 16 on which the previously-noted component parts are installed. As shown in Fig. 1, the supply unit 8 is provided in the fuel tank so that the supply unit is installed on the fuel tank through the unit body 16 and is contact with the fuel within the fuel tank 1. Reference sign 9 denotes the fuel pump for discharging the fuel in the fuel tank 1 to the exterior. As seen in Fig. 2, the fuel pump 9 is constructed by a pump body 9A formed into a substantially cylindrical shape, a suction port 9C provided at the lower end of the pump body 9A and connected to a filter portion 9B, and a discharge port 9D provided at the upper end of the pump body 9A. The pump body 9A employs a lead wire 9E for supplying electric power from the external power source. The fuel pump 9 is installed on the unit body 16 , the discharge port 9D is fitted into the fuel inlet port 19, and the lead wire 9E is connected to the connector portion 22 of the unit body 16. Under this condition, the fuel of the fuel tank 1 sucked in through the suction port 9C is discharged from the discharge port 9D into the fuel inlet port 19. Reference sign 10 denotes the fuel filter of the present example, provided for purification of the fuel discharged from the fuel pump 9. As seen in Fig. 2, the fuel filter 10 is constructed by the filter case 11 and the filter element 14, as will be described later. Reference sign 11 denotes the filter case serving as a casing for the fuel filter 10. The filter case 11 is formed of a synthetic-resin material containing anti-static agent, a metallic material containing anti-static agent, or the like, and materially has an electric conductivity. Additionally, as seen in Fig. 3, the filter case 11 is constructed by the inside wall portion 11A whose central portion is curved in a substantially U shape in the longitudinal direction, the outside wall portion whose central portion is curved in a substantially U shape in the longitudinal direction, a pair of side wall portions 11C, 11C integrally connecting the inside wall portion 11A with the outside wall portion 11B at the position where the filter case opposes the outer periphery of the fuel pump 9, and a bottom wall portion 11D shown in Fig. 2. The filter case 11 has a lateral cross section of a substantially U shape, as a whole, and is formed as a casing with a bottom at its lower end and an opening at its upper end. The filter case defines therein a filter accommodation space 12 which is located and defined between the inside wall portion 11A and the outside wall portion 11B for accommodating the filter element 14. As seen in Fig. 3 , also provided midway of the inside wall portion 11A in the longitudinal direction is a partition wall portion 11E projected toward the outside wall portion 11B into the U shape. The partition wall portion 11E defines a vertically-extending fuel flow passageway 12A in the filter accommodation space 12 and between the inside wall portion and the partition wall portion. The fuel flow passageway 12A communicates at its upper end with the fuel supply conduit 20 of the unit body 16, and also communicates at its lower end with the filter element 14 through a space on the bottom wall portion 11D. Additionally, the filter case 11 is fitted at the upper end into the filter mounting portion 18 of the unit body 16 , for installation on the unit body 16 . The fuel within the fuel tank 1 enters into and outgoes from the inner space 13 surrounded by the inside wall portion 11A in a substantially U shape. This permits the filter case 11 to contact with the fuel in the fuel tank 1 through the inside wall portion 11A, the outside wall portion 11B, the respective side walls 11C, and the bottom wall portion 11D, with a wide contact area. Reference sign 14 denotes the filter element accommodated in the filter accommodation space 12 of the filter case 11. Although, when the filter element 14 is conditioned in the non-accommodated state, its lateral cross section is straight, the substantially U-shaped cross section is created by curving the straight element. The side wall surface of the filter element is brought into abutted-contact all around with the inside wall surface of the filter case 11. Also, a fluid chamber 15 is formed within the filter case 11 and is defined at the upper end of the filter element 14 and between the base portion 17 of the unit body 16 and the filter element upper end. The filter element 14 filtrates and purifies the fuel entering into the fluid chamber 15, and then flows out the purified fuel through the lower end of the filter element into the fuel flow passageway 12A. Reference sign 16 denotes the unit body constructing the housing of the supply unit 8 . As seen in Figs. 2 and 3, the unit body 16 is made of synthetic resin material having an electric insulation property and formed into a substantially oval plate. The unit body is equipped with the base portion 17 formed with a plurality of collared portions 17A, 17A, ··· , circumferentially spaced apart from each other and engaged with the opening 1B of the fuel tank 1, and the filter mounting portion 18 formed into a frame projected downward by a predetermined length from the base portion 17 for installing thereon the upper end of the filter case 11 of the fuel filter 10. As shown in Fig. 3, the base portion 17 is formed integral with the fuel inlet port 19 which is formed as a substantially T-shaped conduit. As clearly seen in Fig. 2, one end of the fuel inlet port 19 projects downward from the base portion 17, and is connected at its lower end to the discharge port 9D of the fuel pump 9 so that the discharge port is fitted into the inner periphery of the fuel-inlet lower end. The other end of the fuel inlet port 19 is branched in two directions to open into the fluid chamber 15 of the fuel filter 10. Moreover, as seen in Fig. 2, the base portion 17 is formed with the fuel supply conduit 20 which is formed into a L shape, extending upwards, and communicates with the fuel flow passageway 12A of the filter case 11, and the return conduit 21 which is L-shaped, extending upwards at the upper end in the same manner as the fuel supply conduit 20, and the lower end extends downwards from the base portion 17 through the inner space 13. Also, the base portion 17 is formed with the connector portion 22 for the fuel pump 9. The connector portion 22 is connected through the lead wire or the like to the electric power circuitry (not shown) provided in the exterior of the fuel tank 1. As regards the unit body 16 , the respective collared portions 17A of the base portion 17 are engaged with the outer surface of the opening 1B of the fuel tank 1, indicated by the one-dotted line of Fig. 3, and are fixedly connected to the lid plate 1A of the fuel tank 1 by means of locking pins installed between the respective two adjacent collared portions 17A to prevent the respective collared portions from falling out from the opening. With the previously-described arrangement, the fuel supply device of the present example operates as follows. First of all, when the fuel pump 9 shown in Fig. 2 is driven, the fuel of the fuel tank 1, sucked in from the suction port 9C, is discharged from the discharge port 9D of the fuel pump 9 into the fuel inlet port 19 of the unit body 16, and then flows into the fluid chamber 15 of the fuel filter 10. Thereafter, the fuel flows through the filter element 14 from the upper end to the lower end, and thus filtered and purified, and then flows along the bottom wall portion 11D of the filter case 11 through the fuel flow passageway 12A into the fuel supply conduit 20, and further supplied from the fuel supply conduit 20 into the exterior of the fuel tank 1 within toward the engine 2. Also, the fuel is supplied through the line 5 shown in Fig. 1 into the fuel line 3, and then injected into the cylinders of the engine 2 via the respective fuel injection valves 4. The fuel pressure of fuel in the fuel line 3 is regulated by means of the pressure regulator 6, and thus surplus fuel is returned through the return line 7 into the return conduit 21 of the supply unit 8, and then returned into the fuel tank 1 via the return conduit 21. On the other hand, when the fuel, entered into the fuel filter 10, flows from the fluid chamber 15 through the filter element 14 and the fuel flow passageway 12A into the fuel supply conduit 20, the fuel flow produces friction with the inner wall surface of the filter case 11, and whereby the filter case 11 tends to be charged with static electricity. Hereupon, since the fuel filter 11 are brought into contact with the fuel, stored in the fuel tank 1 and having a slight electric conductivity, through the inside wall portion 11A, the outside wall portion 11B, the respective side wall portions 11C, and the bottom wall portion 11D, the static electricity charged in the filter case 11 can be discharged through the outer surfaces of these wall portions into the fuel within the fuel tank 1. In this manner, in the present example, the filter case 11 of the fuel filter 10 , which is provided in the fuel tank 1, is made of a material having an electric conductivity materially and formed into a substantially U-shape in lateral cross section, and the fuel within the fuel tank 1 can be entered into and outgone from the inner space 13 surrounded by the inside wall portion 11A. Thus, the inside wall portion 11A and the outside wall portion 11B of the filter case 11 can be curved and formed into the U shape, and whereby the surface area of these wall portions can be certainly enlarged, and at the same time the filter case 11 can contact with the fuel within the fuel tank 1 through the inside wall portion 11A, the outside wall portion 11B, the respective side wall portions 11C, and the bottom wall portion 11D, with an adequately wide contact area. For the reasons discussed above, in the case that the filter case 11 is charged with static electricity due to friction with the fuel flowing through the interior of the filter case, the static electricity charged in the filter case 11 can be effectively escaped through the inside wall portion 11A, the outside wall portion 11B, the respective side wall portions 11C, and the bottom wall portion 11D into the fuel prevailing in the fuel tank 1, by virtue of the electric conductivity of the fuel. Accordingly, even when the electric conductivity of the fuel is very small, the static electricity charged in the filter case 11 can be escaped into the fuel with the sufficiently increased contact area between the filter case 11 and the fuel. Therefore, even when the filter case 11 is charged with static electricity, the device according to the present embodiment can prevent the static electricity from being accumulated in the filter case 11, and whereby the reliability of the fuel supply device can be enhanced. Additionally, the fuel pump 9 and the substantially U-shaped fuel filter 10 are provided so that the respective side wall portions 11C of the fuel filter 10 are opposed to the outer periphery of the fuel pump 9, and thus there is less undesirable aperture between the fuel filter and the fuel pump, as compared with such a construction that the U-shaped portion of the outside wall portion 11B is opposed to the outer periphery of the fuel pump 9. These component parts can be compactly installed on the unit body 16, and simultaneously the supply unit 8 can be certainly small-sized. Referring now to Figs. 4 and 5, there is shown the embodiment of the present invention. The embodiment is characterized in that the outer periphery of the fuel pump is surrounded by the inside wall portion of the filter case formed as a double cylinder. In this embodiment, the same signs used to designate elements in the example according to figures 1-3 will be applied to the corresponding elements used in this embodiment, and thus detailed description of these elements will be omitted because the above description thereon seems to be self-explanatory. In the drawings, reference sign 31 denotes the supply unit of the embodiment. In the same manner as the example according to figures 1-3, the supply unit 31 is constructed by the fuel pump 9 , the fuel filter 32 , and a unit body 38 described later, on which the former two component parts are installed. In this embodiment, the fuel filter 32 is formed annularly by a filter case 33 and a filter element 36 , which will be hereinafter described, so that the fuel filter is disposed to surround the outer periphery of the fuel pump 9. Reference sign 33 denotes the filter case formed as a double cylinder. As seen in Fig. 4, the filter case 33 is made of a material practically having an electric conductivity, and is formed with a cylindrical inside wall portion 33A surrounding the outer periphery of the fuel pump 9, a cylindrical outside wall portion 33B surrounding the inside wall portion 33A through the filter element 36, and a bottom wall portion 33C. The filter case 33 is formed as an annular casing having an opening at its upper end, in such a manner as to define a filter accommodation space 34 between the inside wall portion 33A and the outside wall portion 33B. Additionally, the filter case 33 is fitted at its upper end into the filter mounting portion 40 of the unit body 38, for installation of the filter case on the unit body 38. An annular inner space 35 is defined between the inside wall portion 33A of the filter case 33 and the outer periphery of the fuel pump 9 , so that the fuel in the fuel tank 1 enters into or outgoes from the inner space 35 through the lower opening. Hereby, the filter case 33 is brought into contact with the fuel within the fuel tank 1 through the inside wall portion 33A, the outside wall portion 33B, and the bottom wall portion 33C. Reference sign 36 denotes the annular filter element accommodated in the filter accommodation space 34 of the filter case 33. As seen in Fig. 4, the filter element 36 abuts at its upper end with the base portion 39 of the unit body 38, and abuts at its lower end with the bottom wall portion 33C of the filter case 33. Also, an annular inner fluid chamber 37A is defined within the filter case 33 and between the filter element 36 and the inside wall portion 33A, whereas an annular outer fluid chamber 37B is defined between the filter element 36 and the outside wall portion 33B. The filter element 36 filtrates fuel flowing into the outer fluid chamber 37B and feeds the filtered fuel into the inner fluid chamber 37A, for purification of the fuel. Reference sign 38 denotes the unit body of the supply unit 31. Almost in the same manner as the example according to figures 1-3, as shown in Fig. 5, the unit body 38 is constructed by a base portion 39 formed into a substantially circular plate, a filter mounting portion 40 projected downward from the base portion 39 just as seen in Fig. 4, and a fuel inlet port 41 integrally connected to the base portion 39 and having a substantially C-shaped cross section. The fuel inlet port 41 projects, at its one end, downward from the central portion of the base portion 39, so that the discharge port 9D of the fuel pump 9 is fitted into the inner periphery of the fuel inlet port. The other end of the fuel inlet port 41 opens into the outer fluid chamber 37B of the filter case 33. Furthermore, as seen in Fig. 4, the base portion 39 is formed with a L-shaped fuel supply conduit 42 extending upwards and communicating with the inner fluid chamber 37A of the filter case 33, a return conduit 43 which is L-shaped, extending upwards at the upper end and extending downwards from the base portion 39 at the lower end, and a connector portion 44 of the fuel pump 9. Thereby, the fuel of the fuel tank 1, discharged from the discharge port 9D of the fuel pump 9, flows through the fuel inlet port 41 into the outer fluid chamber 37B defined within the fuel filter 32, and filtrated by the filter element 36, and then the filtrated fuel flows out into the inner fluid chamber 37A and is supplied from the inner fluid chamber 37A via the fuel supply conduit 42 to the exterior of the fuel tank 1. As set out above, with the arrangement of this embodiment, it is possible to obtain essentially the same operations and effects as the example according to figures 1-3. That is, the static electricity charged in the filter case 33 can be escaped or released into the fuel in the fuel tank 1 through the inside wall portion 33A of the filter case 33, the outside wall portion 33B, and the bottom wall portion 33C. Particularly, in this embodiment, the device is constructed so that the fuel within the fuel tank 1 enters into and outgoes from the inner space 35 defined between the outer periphery of the fuel pump 9 and the inside wall portion 33A of the fuel filter 33 provided to surround the outer periphery of the fuel pump, whereby the adequate contact area enough to escape the static electricity can be provided between the filter case 33 and the fuel in the fuel tank 1. Moreover, it is possible to greatly reduce undesired aperture defined between the fuel pump and the fuel filter, by disposing the fuel filter 32 in such a manner as to surround the outer periphery of the fuel pump 9. Thus, the supply unit 31 can be more compactly constructed.

Claims: A fuel supply device provided within a fuel tank (1), comprising: a fuel pump (9) disposed within the fuel tank (1); a fuel filter (10) disposed within the fuel tank (1), the fuel filter (10) arranged about the fuel pump (9) for filtering fuel discharged from the fuel pump (9), the fuel filter (10) consisting of a filter case (11; 33) and a filter element (14; 36) disposed in the filter case (11; 33); the filter case (11, 33) being made of an electrically conductive material and formed with an inside wall portion (11A; 33A) and an outside wall portion (11B; 33B) both of which are adapted to be in contact with fuel in the fuel tank, and which define a filter accommodation space (12; 34) therebetween; the filter case (11; 33) having a substantially U-shaped cross section; characterized in that the filter case (11; 33) encloses the fuel pump (9) in a spaced, contact-free relationship and permits fuel to flow freely in and out of a space defined between the inside wall portion (11A; 33A) and an outer periphery of the fuel pump (9). The fuel supply device as claimed in claim 1, characterized in that the filter case (11; 33) is formed as a double cylinder, so that the inside wall portion (11A; 33A) cylindrically surrounds the outer periphery of the fuel pump (9) in a spaced, contact-free relationship therewith, and the outside wall portion (11B; 33B) cylindrically surrounds an outer periphery of the inside wall portion and encloses the filter element (14; 36). The fuel supply device (31) as claimed in claim 1, characterized in that the filter case (33) is formed as a double cylinder, so that the inside wall portion (33A) cylindrically surrounds the outer periphery of the fuel pump (9) with an aperture, and the outside wall portion (33B) cylindrically surrounds an outer periphery of the inside wall portion (33A) through the filter element (36).

Inventors: AOYAMA TAIKI, HASHIMOTO TAKASHI, OKADA YOSHIHIRO, TAKAHASHI KOJI, AOYAMA, TAIKI, HASHIMOTO, TAKASHI, OKADA, YOSHIHIRO, TAKAHASHI, KOJI, TAKAHASHI, Koji, c/o Unisia Jecs Corporation
Applicants: ATSUGI UNISIA CORP, NISSAN MOTOR, NISSAN MOTOR CO., LTD., UNISIA JECS CORPORATION
Application year: 1998
Main classification: F02M37
IPC codes: F02M37, B01D27, B01D35, B01D29, F02B77