JP2005220817A - Fuel pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel pump in which improvement in corrosion resistance can be attained even though off-quality fuel is used. <P>SOLUTION: The fuel pump 10 comprises an inner rotor 23 having an external-teeth part on the outside periphery, and an outer rotor 24 having an internal-teeth part on the inside periphery and forming a plurality of pumping chambers between the inner rotor 23 and the outer rotor 24, and casings 21, 22 for holding the inner rotor 23 and the outer rotor 24. Fuel in a fuel tank is sucked by rotating the inner rotor 23 to be delivered into an internal combustion engine. The inner rotor 23 and the outer rotor 24 are respectively covered with films 23a, 24a having resistance to off-quality fuel. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a fuel pump, and is suitable for application to a gear-type fuel pump such as a trochoid pump.

  As a fuel pump, for example, a gear pump such as a trochoid pump is known in a fuel supply device of an internal combustion engine. The gear pump sucks up and discharges fuel from a fuel tank (see Patent Document 1). This type of gear-type pump includes an inner rotor having an outer tooth portion on the outer periphery, an outer rotor having an inner tooth portion on the inner periphery, a casing for accommodating the inner rotor and the outer rotor, and the like.

The inner rotor and the outer rotor are made of an iron-based material, and the casing that is a mating surface that slides with these rotors is made of an aluminum die-cast material and subjected to an alumite treatment. By rotating and driving the inner rotor having the number of teeth one less than that of the outer rotor, the outer rotor meshing with the inner rotor is rotated in the same direction as the inner rotor. The fuel is discharged by moving while changing the gap volume in the plurality of pump chambers formed between the inner rotor and the outer rotor.
JP-A-5-202861

  Although it is possible to manufacture at low cost with the conventional configuration, there is a concern about corrosion of the iron-based material inner rotor and outer rotor when exporting to destinations with different fueling environments such as fuel used. For example, when an inferior fuel containing organic acid or sulfur is used, the inner rotor and the outer rotor may be corroded.

  Further, the inner rotor, the outer rotor, and the mating surfaces that slide with these rotors have a problem in that friction due to sliding between the iron-based material and the anodized aluminum die casting material is large, resulting in performance loss.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a fuel pump capable of improving corrosion resistance even when using poor fuel.

  Another object of the present invention is to provide a fuel pump that can improve corrosion resistance even when a poor fuel is used, and can obtain a stable flow rate without loss of performance.

  According to the first aspect of the present invention, the inner rotor having the outer teeth on the outer periphery, the outer rotor having the inner teeth on the inner periphery and forming a plurality of pump chambers with the inner rotor, the inner rotor and the outer rotor are accommodated. A fuel pump that sucks fuel in the fuel tank and discharges it to the internal combustion engine by rotating the inner rotor by rotating the inner rotor, and that the inner rotor and the outer rotor are formed with a film having poor fuel resistance. Features.

  According to this, since a coating having poor fuel resistance such as nickel plating and chrome plating is formed on the inner rotor and the outer rotor, for example, an iron-based material or the like without changing the basic material configuration of the inner rotor, the outer rotor, and the casing. The inner rotor and the outer rotor which are formed by the above and are relatively easily corroded can be prevented from being deteriorated by a poor fuel containing an organic acid or sulfur.

  According to claim 2 of the present invention, a resin film capable of reducing sliding resistance is formed on a mating surface of the casing that slides relative to the inner rotor and the outer rotor.

  According to this, a resin film capable of reducing sliding resistance, such as a fluororesin coating, is formed on the mating surface that slides relative to the inner rotor and the outer rotor. Even when it is rotationally driven, a stable discharge flow rate can be obtained without performance loss.

  According to claim 3 of the present invention, the coating formed on the inner rotor and the outer rotor is preferably formed of a nickel plating layer. Thereby, while ensuring substantially the same mechanical strength as the base material of an inner rotor and an outer rotor, the surface of an inner rotor and an outer rotor can be corrosion-protected.

  According to claim 4 of the present invention, the resin film is characterized in that the mating surface is coated with silicon resin or fluororesin.

  According to this, since the non-adhesive silicon resin or fluororesin is used for the resin film, the sliding resistance due to friction between the inner rotor and the outer rotor and the mating surface of the casing can be reduced.

  According to claim 5 of the present invention, the casing is made of an aluminum die-cast material and is anodized.

  According to this, it is suitable for application to a fuel pump for vehicles having a casing formed of an aluminum die-cast material and anodized. For example, in a vehicle fuel pump that requires fuel saving, an inexpensive and lightweight base material can be maintained.

  Hereinafter, embodiments of the fuel pump of the present invention will be described with reference to the drawings. FIG. 1 is a view showing a fuel pump of the present embodiment, and is a partially exploded view of the fuel pump of FIG. FIG. 2 is a cross-sectional view showing an example of the fuel pump of the present embodiment. 3 is an arrow view of the inner rotor and outer rotor in FIG. 2 as viewed from the inside.

  A fuel pump 10 shown in FIG. 2 is housed in a fuel tank of a two-wheel or four-wheel vehicle (not shown), for example, and supplies fuel sucked from the fuel tank to the engine side.

  The fuel pump 10 includes a pump unit 20 and a motor unit 30 as an electromagnetic drive unit that drives the pump unit 20. The motor unit 30 is a DC motor with a brush, and has a configuration in which a permanent magnet is annularly arranged in a cylindrical housing 11 and an armature 32 is arranged concentrically on the inner peripheral side of the permanent magnet. The armature 32 is rotatably accommodated in the motor unit 30, and a coil is wound around the outer periphery of the core 32a. The commutator 50 is formed in a disk shape, and is disposed on the armature 32. Power is supplied to the coil from a power source (not shown) through a terminal 48 embedded in the connector 47, a brush (not shown), and a commutator 50. The armature 32 is rotated by the supplied electric power.

  The pump unit 20 includes an inner rotor 23, an outer rotor 24, a casing body 21, and a casing cover 22. The casing body 21 and the casing cover 22 constitute a casing that houses the inner rotor 23 and the outer rotor 24. An inner rotor 23 and an outer rotor 24 as inner rotating members of the casings 21 and 22 are rotatably accommodated.

  The outer rotor 24 is formed in a substantially disk shape, and an inner tooth having a predetermined number of teeth (9 teeth in this embodiment) formed by a trochoid curve is formed on the inner periphery formed in the substantially disk shape. Yes. The inner rotor 23 is formed with a through hole at the rotation center thereof, and the rotation shaft 35 is engaged with the through hole and arranged coaxially. The inner rotor 23 is positioned in the rotation direction by a locking portion 35 a of the rotation shaft 35. On the outer periphery of the inner rotor 23, external teeth having a predetermined number of teeth (eight teeth in this embodiment) formed by a trochoid curve are formed. The inner rotor 23 is housed eccentrically in the outer rotor 24, and the outer teeth of the inner rotor 23 are meshed with the inner teeth of the outer rotor 24 to form a predetermined number (9 in this embodiment) of pump chambers. The inner rotor 23 and the outer rotor 24 are made of an iron-based material.

  Further, in the present embodiment, as shown in the exploded view of FIG. 1, nickel (Ni) plating layers 23 a and 24 a are formed on the surfaces of the inner rotor 23 and the outer rotor 24. This film (hereinafter referred to as a nickel layer film) is formed by electroless plating. The thickness of the nickel layer film is preferably in the range of about 8 to 12 μm. When the film thickness is 8 μm, it is difficult to secure a wear allowance due to the engagement between the inner rotor 23 and the outer rotor 24. When the film thickness range exceeds 4 μm, the thrust clearance between the inner rotor 23 and the casings 21 and 22 housing the outer rotor 24 increases, and the pump efficiency such as the discharge efficiency is lowered.

  The casing main body 21 and the casing cover 22 are formed by die-casting with an aluminum die-cast material and subjected to an alumite treatment. Furthermore, in the present embodiment, a resin film that reduces sliding resistance is formed on the surface that is a mating surface that slides relative to the inner rotor 23 and the outer rotor 24. In detail, as shown in an exploded view of FIG. 1, a resin film (hereinafter referred to as PTFE (polytetrafluoroethylene), for example, non-adhesive fluororesin) is formed on the surface of the casing cover 22. (Referred to as a coating film) 22a is preferably formed. This is because the inner rotor 23 and the outer rotor 24 are pressed against the surface of the casing cover 22 by the fuel pressurized in the gap space of the pump chamber by the rotational drive of the inner rotor 23. The sliding resistance generated when the inner rotor 23 and the outer rotor 24 are pressed can be reduced.

  The casing body 21 is press-fitted and fixed inside one end of the housing 11, and a bearing 25 is fitted in the center thereof. The casing cover 22 is fixed to one end of the housing 11 by caulking or the like while being covered with the casing body 21. A thrust bearing 26 is press-fitted and fixed at the center of the casing cover 22. One end of the rotary shaft 35 of the armature 32 is supported in a radial direction by a bearing 25 so as to be rotatable, and a thrust load is supported by a thrust bearing 26. The other end of the rotating shaft 35 is supported by a bearing 27 in the radial direction so as to be rotatable.

  A fuel inlet 40 is formed in the casing cover 22, and the inner rotor 23 rotates so that fuel in the fuel tank is sucked into the fuel inlet 40, and the inner rotor that is rotationally driven and the outer rotor that rotates in the same direction as the inner rotor 23. The fuel is pressurized by a known method of moving while changing the gap volume in a plurality of pump chambers formed therebetween. The fuel sucked from the fuel inlet 41 is pressurized by the rotation of the inner rotor 23 and the outer rotor 24, and discharged from the fuel outlet 42 (see FIG. 1) formed in the casing body 21 to the fuel chamber 31 of the motor unit 30. As shown in FIGS. 2 and 3, a suction port 41 communicating with a fuel inlet 41 formed substantially in the axial direction of the casing cover 22 is formed, and the suction port 41 is a direction in which a plurality of pump chambers are arranged side by side. Is formed on the casing cover 22. A discharge port 42a communicating with a fuel outlet 42 formed substantially in the axial direction of the casing body 21 is formed. The discharge port 42a is formed in the casing body 21 along a direction in which a plurality of pump chambers are arranged side by side.

  Next, the operation of the present embodiment having the above-described configuration will be described. When the engine 1 is driven and a drive current is supplied from the connector 47 to the fuel pump 10, the inner rotor 23 rotates together with the rotating shaft 35 of the armature 32. When the impeller 23 rotates, the outer rotor 24 that meshes with the inner rotor 23 rotates in the same direction as the inner rotor 23. With this rotation, the plurality of pump chambers shown in FIG. 3 move in the clockwise direction. Moreover, the volume of the pump chamber increases as it moves clockwise from the 9 o'clock position, and then decreases again. Fuel is sucked from a suction port 41 formed in a range in which the volume of the pump chamber increases. The fuel filled in the pump chamber is discharged from a discharge port 42a formed in a range where the volume of the pump chamber decreases. The fuel discharged from the discharge port 42a through the fuel outlet 42 to the fuel chamber 31 passes around the armature 32 and is discharged from the discharge port 45 to the outside of the fuel pump. Note that a check valve 46 is accommodated in the discharge port 45, and the check valve 46 prevents a back flow of fuel discharged from the discharge port 45.

  Next, the operation and effect of the present embodiment will be described. (1) Nickel plating layers 23a and 24a subjected to nickel (Ni) plating are formed on the inner rotor 23 and the outer rotor 24. Thus, the inner rotor and the outer rotor can be protected from bad fuel containing organic acid, sulfur and the like without changing the basic material configuration of the inner rotor 23, the outer rotor 24, and the casings 21 and 22. Can do.

  The basic material structure is such that the inner rotor 23 and the outer rotor 24 are iron-based materials that are relatively easily corroded, and the casings 21 and 22 are formed of aumi die-cast material and anodized.

  (2) Since the coating having corrosion resistance formed on the inner rotor 23 and the outer rotor 24 is formed of a nickel layer coating, the inner rotor 23 and the outer rotor 24 are secured with substantially the same mechanical strength as the base material of the inner rotor 23 and the outer rotor 24. Can be anticorrosive.

  In addition, it is possible to prevent the nickel layer coating from affecting the casings 21 and 22 serving as mating surfaces that slide with the inner rotor 23 and the outer rotor 24.

  (3) A non-adhesive fluororesin coating film is formed on the mating surfaces of the casings 21 and 22 that slide relative to the inner rotor 23 and the outer rotor 24. Thereby, the sliding resistance which arises in the inner rotor 23 and the outer rotor 24 and the said other surface by rotation of the inner rotor 23 can be made small. Therefore, even when the inner rotor 23 is rotationally driven by the motor unit 30 having a small output as a driving device for driving the pump unit 20, for example, a stable discharge flow rate can be obtained without performance loss.

  (4) The coating film 22a formed on the mating surface is not limited to a fluororesin such as PTFE, and may be a silicone resin as long as it has non-adhesiveness.

  (5) Of the casings 21 and 22, the casing cover 22 is preferable as the mating member that forms the coating film. Since the inner rotor 23 and the outer rotor 24 are pressed against the casing cover 22 by the fuel pressurized in the gap space of the pump chamber by the rotational drive of the inner rotor 23, the sliding resistance generated at this time can be reduced.

  (6) The casings 21 and 22 are formed of an aluminum die-cast material, and the basic material configuration to be anodized is not changed. As a result, it is possible to maintain an inexpensive and lightweight base material in a vehicle fuel pump that is required to save fuel in recent years.

  (7) When the vehicle fuel pump is applied to a two-wheeled vehicle, since the battery capacity is relatively small, the motor unit 30 is generally used with a small output. By applying the fuel pump 10, a stable discharge flow rate can be supplied without performance loss.

(Other embodiments)
In the present embodiment described above, the nickel plating process has been described as the plating process having the resistance to poor fuel. However, as long as the film having the resistance to poor fuel is formed, even the chrome plating process may be used. Good.

  In the present embodiment described above, the fuel itself as the working fluid sucked up and discharged by the fuel pump 10 is not a working fluid having a relatively high corrosiveness, but has a slight corrosiveness due to moisture content or the like. It is suitable for use in a fuel pump used in a refueling environment where bad fuel containing an organic acid or sulfur is used in a destination (exporting country) where there is a risk of using bad fuel.

FIG. 2 is a partially exploded view of the fuel pump of FIG. 1, showing the fuel pump according to the embodiment of the present invention. It is sectional drawing which shows one Example of the fuel pump of embodiment of this invention. FIG. 3 is an arrow view of the inner rotor and outer rotor in FIG. 2 as viewed from the inside.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Fuel pump 20 Pump part 21 Casing main body (casing)
22 Casing cover (casing)
22a Coating film (resin film)
23 Inner rotor 23a Nickel layer coating (film)
24 Outer rotor 24a Nickel layer coating (film)
30 Motor part (drive device)
40 Fuel inlet 42 Fuel outlet

Claims (5)

An inner rotor having external teeth on the outer periphery;
An outer rotor having an inner tooth portion on an inner periphery and forming a plurality of pump chambers with the inner rotor;
A casing that houses the inner rotor and the outer rotor;
In the fuel pump for sucking the fuel in the fuel tank and discharging it to the internal combustion engine by rotationally driving the inner rotor,
A fuel pump, wherein the inner rotor and the outer rotor are formed with a coating having resistance to poor fuel. 2. The fuel pump according to claim 1, wherein a resin film capable of reducing sliding resistance is formed on a mating surface of the casing that slides relative to the inner rotor and the outer rotor. The fuel pump according to claim 1, wherein the coating is formed with a nickel (Ni) plating layer. The fuel pump according to claim 2, wherein the resin film is coated with silicon resin or fluorine resin on the mating surface. The fuel pump according to any one of claims 1 to 4, wherein the casing is made of an aluminum die-cast material and anodized.

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