Patent Application
20080216904
This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2007-057516, filed on Mar. 7, 2007, the entire contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to a fusel supply system for feeding under pressure fuel within a fuel to injectors of an internal combustion engine of a vehicle, and more particularly to a structure capable of improving a mounting property to the inside of the fuel tank and an antivibration property.
2. Description of the Related Art
In order to capture foreign matters such as dust contained in fuel for stable supply of the fuel to, for example, injectors of a fuel injection system mounted on an engine, foreign matters contained in fuel within a fuel tank are firstly removed by a suction filter made of, for example, a nylon mesh material having relatively rough meshes, and then, foreign substances including foreign substances having passed through the suction filter and dust resulting from wear of a brush, a commutator and the like which form a motor unit of the fuel pump are captured by a high-pressure filter such as a filter element made of paper provided downstream of the fuel pump (that is, next stage of the fuel pump along a fuel flow path).
Since the suction filter is located in a so-called upstreammost position in a fuel supply line, the suction filter is generally located in a lowest bottom portion of the fuel tank so that fuel still can be supplied even though fuel remaining with the fuel tank is reduced. On the other hand, in many cases, the high-pressure filter is provided on a flange of the fuel supply system, that is, directly underneath an upper side of the fuel tank so as to send fuel discharged from the high-pressure filter to, for example, a discharge pipe provided on the flange without any delay. Namely, as long as the fuel supply system can be accommodated within the fuel tank having a limited height dimension, it is conceivable that the fuel supply system is provided within the fuel tank to occupy the whole of the height dimension (for example, see JP-B-3256973 (from line 9 in a right-side column on page 3 to line 49 in a left-side column on page 4, FIG. 1); hereinafter referred to as Document 1).
As shown in FIG. 1 of Document 1, since a fuel pump having a relatively large capacity is used, the fuel pump and a high-pressure filter overlap each other, that is, the fuel pump is accommodated within an inner circumference of the high-pressure filter which is formed substantially into a C-shaped configuration (a filter housing in Document 1; and hereinafter referred to as a housing). Therefore, a clearance between an opening in an upper side of a fuel tank and the housing becomes extremely small. Consequently, when accommodating the fuel supply system within the fuel tank, an edge portion of the opening in the upper side may contact with the housing, which may result in fuel leakage from the fuel tank due to a damage made as a result of the contact.
In view of a main feature of Document 1, by dividing the housing into a first housing (a lid) and a second housing (a lower housing) and, furthermore, into an insulating part and a conductive part, a feeding pin can be insert molded in the lid and static electricity can be discharged from the lower housing. As a result, however, a lower housing is required to cover the height dimension of the filter element, and this means that a welding portion between the lid, which prevents the leakage of fuel, and the lower housing has to lie in the vicinity of a root portion where high stress is highly possibly expected to occur. In general, the strength of the welding portion of resins tends to be lower than the strength of matrix resins, and because of this. Therefore, in case strong vibrations generated while the vehicle is being driven are applied to the welding portion, the welding portion may cracks and fuel leakage may be caused.
WO2004/073145 discloses a further miniaturized fuel pump. Namely, a yoke included in the fuel pump includes a first cylindrical yoke disposed on an inner circumference of a ring-shaped magnet of a rare earth and a second cylindrical yoke provided on an outer circumference of the first cylindrical yoke, whereby even with a magnet of a rare earth of a high holding force which requires a strong magnetizing force, the degree of freedom in configuring a magnetic circuit by the magnet and the yoke increases, and the miniaturization of a magnetizer for the magnet and, hence, the reduction in the axial size of the fuel pump are able to be attained. An object of the invention is to provide a fuel supply system in which no fuel leakage is caused from not only the welding portions but also a filter case that accommodates a filter element therein by using a shortened fuel pump.
According to an aspect of the invention, there is provided a fuel supply system including: a flange mounted at an upper opening in a fuel tank; a fuel pump that discharges fuel in the fuel tank; a high-pressure filter that filters fuel discharged from the fuel pump; and a filter case that accommodates the high-pressure filter and includes an upper case and a lower case, the upper case integrally formed with the flange, wherein the fuel pump is fitted to an underside of the lower case to be positioned substantially coaxial with the high-pressure filter.
As shown in
An assembling procedure of this fuel supply system 101 will be described with reference to
In securing the element 6, in the event that for example, a terminal member of a conductive resin (not shown) is attached in advance to the lower case 2 to be exposed from an outer surface of the lower case 2, the projecting surface is welded to the terminal member, and by drawing an earth wire from this terminal member, static electricity generated in the element 6 can be discharged. In addition, although a lower end of the inner tube 6a is closed by virtue of the securing of the element 6 in the way described above, since an inner wall of the lower case 2 forms a through hollow space and a space is formed between an inner wall of the upper case 1a and the element 6, fuel is allowed to flow into the element 6. In addition, a plurality of communication holes which establish a communication between the inside and outside of the inner tube 6a are provided in the vicinity of a lower portion of the upper collar portion of the inner tube 6a, and the inner tube 6a communicates with the discharge pipe 1b. Therefore, a fuel path is secured from a discharge pipe of the fuel pump to the discharge pipe 1b.
An opening 3a is provided in a bottom side of the pump holder 3, and a recess portion is formed to match the configuration of a bottom portion of the fuel pump 7 (see
A fuel suction port 2a is provided in the lower case 2, and this fuel suction port 2a is securely fitted on a discharge pipe 15a of the fuel pump 7 via a connecting pipe 8 when the lower case 2 is engaged with the pump holder 3 through snap-fit in the way described above, whereby the fuel supply system 101 is completed, that is, a fuel flow path from the suction filter 4 to the discharge pipe 1b is completed. By inserting the fuel supply system 101 so completed from an opening in an upper side of the fuel tank (not shown) the opening in the upper side of the fuel tank is closed by the flange 1, and fuel inside the fuel tank is pressurized by driving the fuel pump 7 and supplied to injectors of a fuel injection system via a fuel hose (not shown) that is connected to the discharge pipe 1b.
Next, the fuel pump 7 and driving thereof will be described with reference to
By being bent toward an axial center of a shaft 14 at both end portions, the second cylindrical yoke 11b integrates the following components together which include a bearing holder 15, an inlet housing 21 and an outlet housing 22. In addition, the bearing holder 15, which is formed of an insulating resin mainly made of polyacetal, accommodates therein a check valve 16, a bearing 17 which supports the shaft 14, a conductive brush 18, a coil spring 19 which pushes the brush 18 against a commutator 12a, a lead wire 18a which supplies a current to the brush 18 through a connector 1c (refer to
As for the pump portion 20, a shaft stopper 23 is accommodated in the inlet housing 21, which is formed from a resin, and the inlet port 21a is formed in the inlet housing 21. The outlet housing 22 is also formed from a resin, and a discharge port 22a is provided therein for discharging fuel which is pressurized in a flow path 24 toward the armature 12, and a bearing 25 which rotatably supports the shaft 14 is also accommodated in the outlet housing 22. A D-cut portion 14a formed into a D-shape in cross section at an end portion of the shaft 14 is fitted in a D-shaped hole in a central portion of an impeller 26 formed from a resin and having a plurality of blade grooves formed on an outer circumference thereof. The flow path 24 is formed by the plurality of blade grooves on the impeller 26 and recessed grooves 21b, 22b respectively formed on the inlet housing 21 and the outlet housing 22.
Next, the operation of the fuel pump 17 will be described. When current is supplied from the battery (not shown) to the armature 12 via the connector 1c, the lead wire 18a, the brush 18 and the commutator 12a, the armature 12 rotates together with the impeller 16 on the shaft 14 as a rotational shaft based on the principle of direct current electric motor. In conjunction with the rotation of the impeller 26, fuel within the fuel tank is introduced to the suction port 21a after foreign matters contained therein have been removed at the suction filter 4. Then, the fuel is pressurized within the flow path 24 and passes through the discharge port 22a, thereby entering a space within the motor portion 10. When flowing through a space between the armature 12 and the magnet 13 inside the motor portion 10, the pressurized fuel cools the armature 12 and causes the check valve 16 to open so as for the fuel to be discharged from the discharge pipe 15a. The discharged pressurized fuel is introduced into the element 6, where foreign substances including foreign matters having passed through the suction filter 4 and dust resulting from wear of the brush 18 and the like are captured, and is thereafter supplied to injectors of the fuel injection system. These are the summary and configuration of the fuel supply system of the embodiment.
Although not described in detail, since in particular, the axial length of the fuel pump 7 is suppressed as much as possible, as shown in
In addition, since the filter case 5 is formed by welding the upper case 1a and the lower case 2 together, there occurs neither fuel leakage from the securing portion where the upper and lower cases are secured to each other through such welding nor reduction in fuel pressure due to such a fuel leakage. Furthermore, in the embodiment, since static electricity generated when the pressurized fuel passes through the element 6 is discharged via the inner tube 6a, an inexpensive insulating resin is used for the upper case 1a having a relatively large surface area, and since the upper case 1a is formed integrally with the flange 1, as described above, the securing portion resulting from the welding is provided below the element 6. Namely, since the securing portion is spaced apart from the root portion so that generation of stress is reduced remarkably, the inexpensive fuel supply system can be provided which is free from fuel leakage from the securing portion which would otherwise be caused due to vibrations being applied thereto.
Furthermore, when forming (welding) the filter case 5, since the lower end face of the upper case 1a is flash with the projecting surface of the lower collar portion of the inner tube 6a, and the upper end faces of the lower case which respectively forms the receiving surfaces of the lower end face and the projecting surface are also flush with each other, the so-called heat plate welding becomes possible, whereby in conjunction with the fact that the formation of the filter case 5 is implemented at the same time that the element 6 is fixed, the production costs can be expected to be reduced. In addition, in this embodiment, although a pressure regulator used to maintain the pressure of fuel in supply thereof is not included, such a pressure regulator is not necessarily attached to the fuel supply system or is not necessarily an element in the fuel supply system. Instead, a method may be adopted in which a pressure regulator is provided outside the fuel tank and between the discharge pipe 1b and the injectors, and a pipe for excess fuel therefrom is inserted into the fuel tank.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2007-057516 | Mar 2007 | JP | national |
