Patent Application
20080216801
This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2007-057517, 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 fuel supply system for feeding under pressure fuel within a fuel tank to injectors and the like of an internal combustion engine of a vehicle and more particularly to the reduction of noise generated from the fuel supply system.
2. Description of the Related Art
By means of the recent technical innovation, noise generated from vehicles (in particular, motor vehicles fueled by gasoline) tends to be reduced. This reduction of noise largely owes not only a reduction of vibrations or noise generated from an engine but also improvements in an engine starting system and a vehicle generator and a reduction of operation noise of solenoid valves, as well as improvements in elastic supporting constructions for power train units such as the engine and a transmission. As a result, the quietness of the vehicle has been increased remarkably and still continues to be increased further.
The quietness of the vehicle constitutes a main factor to determine the sense-related quality of the vehicle. Therefore, operation noise of a fuel system responsible for stable fuel supply to injectors, which is generated in association with driving thereof, cannot be an exception any longer. In recent years, it is an increasing tendency for the fuel supply system to be provided within a fuel tank in order to secure an accommodating capacity within an engine compartment. However, it is necessary to avoid deterioration of the riding comfort and the product quality, due to the operation noise of the fuel supply system propagating through the fuel tank to be eventually transmitted to the inside of a passenger compartment, which results in a reduction in the sense-related quality of the vehicle, in other words, the driver and other occupants in the vehicle having to feel uneasiness or uncomfortableness.
JP-A-2000-45900 (lines 41 to 49 in a left-side column on page 3, and FIG. 2; hereinafter referred to as Document 1) discloses a fuel supply device including a vibration isolating rubber provided between a fuel pump and a bracket for holding the posture of the fuel pump and having a damping portion directed toward a fitting portion with the bracket, thereby effectively damping vibrations of the fuel pump. JP-A-2002-155823 (lines 6 to 10 in a left-hand side column on page 5, FIG. 1; hereinafter referred to as Document 2) discloses a fuel supply device that allows excess fuel from a pressure regulator to be introduced into a fuel tank through a sedimentation flow path formed in a space defined by an inner peripheral wall of a pump holder, an outer periphery of a fuel pump, a lower end surface of a main housing and a vibration absorber, thereby reducing discharge noise of a pressure regulator.
Although the vibration isolating rubber (Document 1) and the vibration absorber (Document 2) can absorb vibrations by fixedly holding the fuel pump is fixedly held, it is difficult to sufficiently suppress the propagation of noise to the fuel tank. This is because, in the case of Document 2 (see FIG. 5 of Document 2), the surfaces of the fuel pump and the vibration absorber and the surfaces of the vibration isolating bed and the pump holder are arranged very closely to each other in order to secure the sedimentation flow path. In this regard, in Document 1, in consideration of transmission of vibrations to the bracket, the area of a distal end of a projection is made extremely small to transmit vibrations thereto by way of the damping portion, so that the damping effect can be expected to be provided to some extent. However, since a projecting portion (denoted by reference numeral 12 in Document 1) of the fuel pump and a pump abutment surface (denoted by reference numeral 22a in Document 1) of the vibration isolating rubber are in tight contact with each other over a semicircular shape, it is sufficiently expected that original vibrations themselves are large, and hence, it is natural to consider that there has been a certain limitation to sufficient suppression of noise propagation from the bracket and, furthermore, the fuel tank only by damping of the originally large vibrations. While the main object of Document 2 is to capture foreign substances contained in excess fuel from the sedimentation flow path, even though the excess fuel is caused to flow by way of the sedimentation flow path, the excess fuel is eventually directly discharged back into the fuel tank. In particular, in the event that the fuel level is situated below an outlet (FIG. 8 of Document 2) of the sedimentation flowpath, collision noise generated when the excess fuel is discharged back into the fuel tank is propagated through the fuel tank to be transmitted to the inside of the passenger compartment, whereby the sense-related quality of the vehicle may be reduced.
The invention has been made in view of the above circumstances, and an object thereof is to provide a fuel supply system capable of suppressing noise associated with discharge of excess fuel from a pressure regulator and propagation of vibrations associated with driving of a fuel pump.
According to an aspect of the invention, there is provided a fuel supply system provided in a fuel tank including: a fuel pump that sucks fuel reserved within the fuel tank via a suction filter and discharges the sucked fuel; a pressure regulator that maintains pressure of the fuel discharged from the fuel pump within a predetermined range; a pump holder that holds the fuel pump and the pressure regulator; and a cushioning rubber extending in radial and axial directions of the fuel pump between the pump holder and the fuel pump for damping vibrations associated with driving of the fuel pump, wherein excess fuel is introduced in a flow path from the pressure regulator to the suction filter, the flow path including: a gap defined between the pump holder and the cushioning rubber; and a gap defined between the cushioning rubber and the fuel pump.
In
As is shown in
An assembly procedure of the fuel supply system 101 will be described The high-pressure filter 8 is inserted from a lower side of the upper case 1a as viewed in the drawing so that the high-pressure filter 8 abut on a ceiling of the upper case 1a, which allows the high-pressure filter 8 to communicate with the discharge pipe 1b and lower end faces of the upper case 1a to be flush with the high-pressure filter 8. Since not only the upper case 1a but also the high-pressure filter 8 are secured to the lower case 2, for example, by heat plate welding the lower case 2 to the lower end faces of the upper case 1a, as is described above, what is formed by securing the upper case 1a and the lower case 2 together is referred to as the filter case 51. Static electricity is generated when fuel passes through an element 8a of the pressure-filter 8, and the generated static electricity is stored in an inner tube 8b which is formed from a conductive resin and by which the element 8a is sandwiched and held. Therefore, it is preferable that a terminal member (not shown) formed from a conductive resin is welded together with the inner tube 8b to be exposed from the filter case 51 when the heat plate welding is performed, and the ground wire that has been described above is connected to the terminal member, thereby easily discharging the static electricity.
The cushioning rubber 10 is laid on an inner bottom 3a of the pump holder 3, and thereafter, the fuel pump 7 is inserted into the pump holder 3. As shown in
The pressure regulator 9 is liquid-tightly fitted in a terminal end 2a of a return flow path of the lower case 2 via an O-ring 11, and thereafter, an engagement hole 3c in the pump holder 3 is engaged with an engagement projection 2b, whereby the lower case 2 (the filter case 51) is engaged with the pump holder 3 through snap-fit. By this engagement, the pressure regulator 9 is held in the pump holder 3 as well as a connecting pipe 12 fitted on a discharge port 7c of the fuel pump 7 is securely and liquid-tightly fitted in a fuel suction port 2c provided in the lower case 2. The fuel suction port 2c communicates with the element 8a, and as a result, a fuel flow path from the suction filter 4 to the discharge pipe 1b is secured. Then, the fluid level detector 5 is mounted on what has been assembled heretofore, and the lead wires 6 are connected to the connector 1d, whereby the fuel supply system 101 illustrated in
The operation of the fuel supply system 101 will be described based on the configuration that has been described above. Namely, when a current is supplied from a battery (not shown) to the fuel pump 7 via the connector 1d and the lead wire 6, a shaft (not shown) within the fuel pump 7 rotates, and an impeller (not shown) rotates together with the shaft as a rotational shaft. In conjunction with the rotation of the shaft and the impeller, the fuel 100 within the fuel tank 99 is introduced into the fuel pump 7 from the suction port 7c after foreign substances contained in the fuel has been removed at the suction filter 4 and is discharged from the discharge port 7c. The fuel, which is pressurized and discharged, is then introduced into the element 8a. After the element 8a captures foreign substances including the foreign substances having passed through the suction filter 4 and dust resulting from wear of the brush and the like of the fuel pump, and the fuel is thereafter supplied to the injectors via the discharge pipe 1b. In addition, as described above, the pressure of the fuel supplied to the injectors is held at the predetermined value by the pressure regulator 9, and as a result of the pressure of the fuel being held at the predetermined value, fuel which becomes excess is discharged from the pressure regulator 9 by way of the return piping 1c. The fuel so discharged is to be sucked up again via the suction filter 4.
While operation noise is generated in association with the rotation or driving of the fuel pump 7, in this embodiment, since the fuel pump 7 is encased by the pump holder 3 and the lower case 2 so as to reduce the exposure of the fuel pump 7 to as low a level as possible, the emission of the operating noise so generated can be suppressed. In addition, as is obvious from the
As shown in
(1) between the inner wall 3e and the wall 10g=>between the inner bottom 3a and the outer bottom 10c=>between the opening 3b and the opened projection 10f (see
(2) between the outer circumferential surface 7a and the wall 10g=>between the bottom side 7a and the inner bottom 10a=>between the connecting portion 4a and the opened projection 10f (see
(3) a hole 10j=>between the inner bottom 3a and the outer bottom 10c=>opening 3d and the opened projection 10f (see
In addition, since the excess fuel is divided into the three flow paths and reaches the suction filter 4 as described above, the excess fuel can be sucked into the fuel tank efficiently for reuse. In addition, since any of the three flow paths is formed into a thin space, the momentum of the jetting flow of fuel from the discharge port can be weakened sufficiently. As a result, since excess fuel in which bubbles having existed in the jetting flow of fuel are removed flows into the suction filter 4, this also assists in realizing the efficient suction for reuse. Furthermore, although swelling of the cushioning rubber 10 is anticipated due to the cushioning rubber 10 being submerged in excess fuel at all times, since an increase in volume due to such swelling is absorbed by opposite surfaces of the first ribs 10h or the second ribs 10i which are arranged in the staggered fashion (or in other words, between the adjacent ribs (10h or 10i), there is no fear that a failure of the cushioning rubber 10 is called for.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2007-057517 | Mar 2007 | JP | national |
