WO2004073145A1

WO2004073145A1 - Dc motor type fuel pump

Info

Publication number: WO2004073145A1
Application number: PCT/JP2003/015692
Authority: WO
Inventors: Seizo Inoue; Kei Yonemori; Hiroyuki Matsuzaki; Kazuyuki Yamamoto
Original assignee: Mitsubishi Denki Kabushiki Kaisha
Priority date: 2003-02-14
Filing date: 2003-12-09
Publication date: 2004-08-26
Also published as: US20050118044A1; TWI235198B; JPWO2004073145A1; CN1692540A; TW200419068A

Abstract

A DC motor type fuel pump delivering fuel while boosting at a pump section (20) secured to the yoke (3) at a motor section (10) as a DC motor at the motor section (10) is driven, wherein the yoke (3) comprises a first tubular yoke (4) having inner circumference being arranged with a rare earth ring magnet (2), and a second tubular yoke (5) being arranged on the outer circumference of the first tubular yoke (4) at a position corresponding to the magnet (2).

Description

Description DC motor fuel pump Technical field

The present invention relates to a DC motor fuel pump that pressurizes fuel by driving a motor and pumps fuel in a fuel tank to an engine. Background art

For example, Japanese Patent Application Laid-Open No. 2000-2626483 discloses a configuration of a DC motor used for a DC electric fuel pump.

In the conventional DC motor disclosed in this publication, a cylindrical yoke and a magnet forming a magnetic circuit in the circumferential direction are arranged on the outer periphery of the armature.

A fixing hole for fixing the magnet is formed in the yoke, and the fixing hole penetrates from the inner peripheral surface to the outer peripheral surface in the thickness direction of the yoke, and has a larger outer peripheral surface than the opening diameter opened to the inner peripheral surface. The opening diameter is larger than the opening diameter.

The magnet is a plastic magnet formed by mixing magnetic powder into a resin and formed into a ring shape. The magnet is formed integrally with the yoke, and a part of itself is inserted into a fixing hole of the yoke.

According to this configuration, a part of the magnet integrally molded with the yoke fits into the fixing hole of the yoke, and the outer peripheral side of the fitting portion is larger than the inner peripheral side. Even if it contracts, it does not come off the yoke and is firmly fixed to the yoke.

DC motors used in conventional DC motor-driven fuel pumps (ie, part of the motor) use fixing holes that penetrate the magnet in the thickness direction of the yoke. Since it is fixed to the yoke, it is necessary to make a through hole on the side of the yoke. Therefore, there is a problem that the yoke is deformed or burrs are generated by the drilling process. "

In addition, when resin mixed with magnetic powder is injected into the inner peripheral side of the yoke and the magnet is molded integrally with the yoke, the resin protrudes from the through holes on the side of the yoke, and burrs are generated on the outer periphery of the yoke. There was a problem.

In addition, since the magnet is deeper than the end of the yoke when viewed in the axial direction, there is a problem in that if the magnet is to be injection-molded from the inner side of the yoke, gate processing is difficult.

The gate is an injection port of a mold at the time of injection molding, and a sol-like resin is injected into the mold from the injection port (that is, the gate). The resin injected into the mold is kept under a predetermined pressure and a predetermined temperature for a predetermined time, thereby completing a molded product. At this time, since the resin is also filled in the injection port portion, the solidified injection port-shaped (projection-shaped) resin remains. Since this part is unnecessary, it is removed by cutting or the like, but this removal processing is gated.

Furthermore, when using a rare earth magnet with a high coercive force that requires a strong magnetizing force as a magnet, a thick yoke is required for the magnetic circuit, but the yoke is a single member. Due to the configuration, there was a problem that the magnetizing device became large.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and there is no need to provide a through hole for fixing the magnet to the yoke on the side surface of the yoke. Another object of the present invention is to provide a DC motor-type fuel pump that has a high degree of freedom in a magnetic circuit configuration composed of a magnet and a shock and that can easily magnetize the magnet with a small magnetizing device. I do. DISCLOSURE OF THE INVENTION A DC motor fuel pump according to the present invention is a DC motor fuel pump that boosts fuel in a pump section fixed to a yoke of the motor section and outputs the fuel when a DC motor of a motor section is driven. The yoke includes a first cylindrical yoke in which a rare-earth ring-shaped magnet is disposed on an inner circumference, and a second cylindrical yoke provided on an outer circumference of the first cylindrical yoke at a position corresponding to the magnet. It is provided with a yoke.

As a result, it is not necessary to provide a through hole for fixing the magnet to the yoke on the side of the yoke, and when using a rare earth magnet, the degree of freedom of the magnetic circuit configuration composed of the magnet and the yoke is reduced. It is possible to realize a DC motor-type fuel pump that can easily magnetize magnets with high cost and a small magnetizing device. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a cross-sectional view of a DC motor fuel pump according to Embodiment 1 of the present invention.

FIG. 2 is an illustration of magnet magnetization.

FIG. 3 is a cross-sectional view schematically showing a magnet and a yoke of a DC motor fuel pump according to Embodiment 2 of the present invention.

FIG. 4 is a cross-sectional view schematically showing a magnet and a first cylindrical yoke of a DC motor fuel pump according to Embodiment 3 of the present invention.

FIG. 5 is a simplified view of a magnet and a bearing holder of a DC motor fuel pump according to Embodiment 4 of the present invention. BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1

Hereinafter, Embodiment 1 of the present invention will be described.

FIG. 1 is a cross-sectional view of a DC motor-type fuel pump (hereinafter, may be simply referred to as a fuel pump) according to Embodiment 1 of the present invention. The fuel pump 1 is composed of a motor unit 10 and a pump unit 20.

First, the motor section 10 will be described. The magnet 2 is formed in a cylindrical shape, and is arranged at a predetermined distance from the outer peripheral surface of the armature 6 on the inner peripheral surface of the yoke 3, and forms a magnetic circuit with the yoke 3 on the outer peripheral surface of the armature 6. I do.

For example, if a magnet material of neodymium (Sm'Fe'N) is injected into the inner peripheral surface of the yoke 3 to form the magnet 2 integrated with the yoke 3, the magnet 2 can be formed. The adhesive between the yokes 3 becomes unnecessary.

The yoke 3 is composed of a first cylindrical yoke 4 and a second cylindrical yoke 5 made of STKM (carbon steel steel pipe for machine structure), and the second cylindrical yoke 5 has the first cylindrical yoke 4 as a shaft. From the direction until it comes into contact with the projection 50a of the second cylindrical yoke 5. '

As will be described later, when the magnet 2 is integrated with the first cylindrical yoke 4 by injection molding from the viewpoint of facilitating magnetization, the first cylindrical yoke 4 is connected to the second cylindrical yoke 5. It is preferable to magnetize the magnet 2 before press-fitting.

A gate for forming the magnet 2 by injection molding is provided on an end face of the magnet 2.

In this case, the thickness of the first cylindrical yoke 4 is 3 mm or less, preferably 2 mm or less, from the viewpoints of the magnetization accuracy and the small deformation when machining the first cylindrical yoke 4. Is good. The second cylindrical yoke 5 integrates the bearing holder 12, the inlet housing 21, and the outlet housing 23 by bending both ends thereof in the axial direction of the shaft 7.

Note that only one end of the second cylindrical yoke 5 may be bent in the axial direction of the shaft 7.

In this case, a bearing holder 12 or a housing composed of an inlet housing 21 and an outlet housing 23 is press-fitted and fixed to the other end that is not bent.

For example, a bearing holder 12 made of an insulating resin mainly composed of a polyester resin has a check valve 13, a bearing 8 that supports a shaft 7, a conductive brush 9, and a brush 9. It houses a coil spring 10 for pressing the commutator 6a and a lead wire 11 for supplying a current to the brush 9 from outside the fuel pump.

Next, the pump section 20 will be described. The inlet housing 21 is formed of a resin, accommodates a shaft stopper 28, and is provided with a suction port for sucking fuel in a fuel tank (not shown).

The outlet housing 23 is formed of resin, is provided with a discharge port 24 for discharging the fuel pressurized in the flow path 27 to the armature 6 side, and has a bearing 25 for supporting the shaft 7. To store.

The impeller (impeller) 26, which is formed of resin and has a plurality of blade grooves on the outer periphery, has a D-shaped hole at the center of the shaft, and an end of a shaft 7 having a D-shaped cross section. The D-cut portion 7a is fitted.

A channel 27 is formed by the concave grooves 21 a and 23 a of the inlet housing 21 and the outlet housing 22 and a plurality of blade grooves of the impeller 26.

Next, the operation of the fuel pump will be described. When a current is supplied to the armature 6 from a battery (not shown) via a power supply terminal (not shown), a lead wire 11, a brush 9, and a commutator 6a, the electric motor is driven by a known DC motor principle. The child 6 rotates together with the impeller 26 around the shaft 7 as a rotation axis.

Along with this, the fuel in the fuel tank (not shown) is introduced from the suction port 22, and is pressurized to 300 KPa to 50 O KPa in the flow path 27, and then discharged from the discharge port 24. On the street, enter the space inside the Morning Night Section 10. This pressurized fuel cools the armature 6 when flowing between the armature 6 and the magnet 2 in the motor section 10, opens the check valve 13 and discharges the bearing holder 12. Discharged from tube 12a. The discharged pressurized fuel is supplied to an unillustrated internal combustion engine.

As described above, the yoke 3 includes the first cylindrical yoke 4 having a small thickness and the second cylindrical yoke 5 having a large thickness.

Therefore, when a rare earth magnet 2 having a strong holding force is used, first, the rare earth magnet 2 is formed on the inner peripheral surface of the first cylindrical yoke 4 by injection molding, and the magnet 2 is then formed. After magnetizing, the first cylindrical yoke 4 having the magnet 2 formed on the inner surface at a desired position of the second cylindrical yoke 5 can be fixed.

By the way, the fuel pump 1 using the rare-earth magnet 2 in the first embodiment is different from the conventional fuel pump using the sintered magnet having a lower holding force than the rare-earth magnet in that the yoke 3 Thick ones are needed.

On the other hand, unlike a general DC motor, the fuel pump 1 needs to be provided with a pump section 20 in the axial direction. Further, since the pressurized fuel passes through the fuel pump 1, the second cylindrical yoke 5 makes the bearing holder 12, the inlet housing 21 and the outlet housing 23 liquid-tight (that is, when the fuel is discharged). (To prevent leakage).

Therefore, the axial length (total axial length) of the second cylindrical yoke 5 is larger than that of a general DC motor.

In the present embodiment, since the yoke 3 is composed of two members, the first cylindrical yoke 4 and the second cylindrical yoke 5, for example, only the length of the first cylindrical yoke 4 is changed. But you can change the magnetic circuit.

Therefore, the degree of freedom of the magnetic circuit can be increased as compared with the case of the conventional one-piece yoke.

Also, by changing the length of the first cylindrical yoke 4, it is possible to cope with a plurality of types of fuel pumps having different required specifications, so that the second cylindrical yoke 5 is shared with a plurality of types of fuel pumps. It is also possible to do.

Further, since the yoke 3 is composed of two members, the first cylindrical yoke 4 and the second cylindrical yoke 5, which is longer in the axial direction than the first cylindrical yoke 4, the yoke 3 has almost no influence on the magnetic circuit. The thickness of the end of the two cylindrical casings 5 can be reduced.

In addition, by reducing the thickness of the end of the second cylindrical yoke 5, bending of the shaft 7 in the axial direction becomes easy, and the fuel pump 1 can be easily assembled.

Also, since the magnet 2 is fixed to the inner periphery of the first cylindrical yoke 4, the position of the magnet 2 in the fuel pump 1 is determined by the position of the second cylindrical yoke 5 of the first cylindrical yoke 4. It can be adjusted by changing the fixed position with respect to.

For this reason, the magnet 2 can be fixed at a convenient position in the first cylindrical yoke 4 in terms of the product configuration.

The first cylindrical yoke 4 and the magnet 2 have the same axial length, and the first cylindrical yoke 4 and the magnet 2 have the same end face position. Thus, a gate for injection molding can be provided near the end of the first cylindrical yoke 4.

In this case, it is necessary to form a hole for an injection molding gate on the side surface of the first cylindrical yoke 4 as in the related art, or to provide a gate for injection molding from the inner peripheral side of the first cylindrical yoke 4. There is no need to do this, and gate processing becomes easier.

Further, since the first cylindrical yoke 4 and the second cylindrical yoke 5 work together as a magnetic circuit in the circumferential direction, the thickness of the first cylindrical yoke 4 and the second cylindrical yoke 5 is increased. The selection range is wide.

For example, by increasing the thickness of the second cylindrical yoke 5 acting as the main magnetic circuit, the first cylindrical yoke 4 can be reduced.

When using a rare earth magnet with a high coercive force that requires a strong magnetizing force for the magnet 2, a thick magnetic circuit corresponding to the coercive force is required, but the first cylindrical yoke 4 and the (2) The wide selection range of the thickness of the cylindrical yoke 5 allows easy handling.

That is, when using a rare earth magnet having a high coercive force that requires a strong magnetizing force for the magnet 2, the first cylindrical yoke 4 is made thinner, and injection molding is performed inside the first cylindrical yoke 4. After the magnet 2 is magnetized, it becomes possible to mount the second cylindrical yoke 5 acting as the main magnetic circuit.

Therefore, the magnet 2 can be magnetized with a small magnetizing device, and the occupied volume of the first cylindrical yoke 4 that is unnecessary for magnetizing the magnet 2 is small, so that the magnetizing accuracy is improved. be able to.

Here, the magnetization of the magnet will be described with reference to FIG.

FIG. 2 is a diagram for explaining a state in which the magnet 2 is magnetized by the magnetizing device 40 with the same magnetizing force 41, and FIG. 2 (a) shows the state of the present embodiment. When the magnet 2 is formed on the inner periphery of the first cylindrical yoke 4 having a small thickness, FIG. 2 (b) shows a conventional cylindrical yoke 4 having a thick wall. The figure shows a case where the magnet 2 is formed on the inner circumference of the magnet.

In the case of FIG. 2 (a), the magnetic flux 42 intersects the first cylindrical yoke 4 and the magnet 2 by a predetermined magnetizing force 41 of the magnetizing device 40, and the magnet 2 is satisfactorily attached. Can magnetize.

On the other hand, in the case of FIG. 2 (b), with the same magnetizing force 41 as in FIG. 2 (a), the magnetic flux 42 does not cross the magnet 2 (so-called short state),

2 cannot be magnetized sufficiently.

Therefore, compared to the case of Fig. 2 (a), a strong magnetizing force is required for magnetizing magnet 2.

If the coefficient of linear expansion of the second cylindrical yoke 5 is selected to be smaller than the coefficient of linear expansion of the first cylindrical yoke 4, the temperature may vary depending on the operation of the fuel pump and the operating environment. Even if the first cylindrical yoke 4 and the second cylindrical yoke 5 expand, the contact between the first cylindrical yoke 4 and the second cylindrical yoke 5 is maintained, and the magnetic circuit is hardly disconnected.

Although the first cylindrical yoke 4 and the second cylindrical yoke 5 have been described as being fixed by press-fitting, they may be shrink-fitted.

Embodiment 2

Hereinafter, a second embodiment of the present invention will be described.

FIG. 3 is a cross-sectional view schematically showing a magnet and a yoke of the DC motor fuel pump according to Embodiment 2, and FIG. 3 (a) shows that the first cylindrical yoke is larger than the second cylindrical yoke. When the axial length is long, FIG. 3 (b) shows the case where the first cylindrical yoke is shorter in axial length than the second cylindrical yoke. The one shown in Fig. 3 (a) was used as a fuel pump 1 by the end face of the magnet 2a abutting on the lip 40a provided on the inner surface of the lower end of the first cylindrical yoke 4a. In this case, the magnet 2 placed inside the first cylindrical yoke 4a at the time of molding or after molding integrally with the inner periphery of the first cylindrical yoke 4a a is prevented from moving downward.

The second cylindrical yoke 5a has the same configuration as that of the first cylindrical yoke 5 described in the first embodiment, and the other configuration (not shown) is the same as that of the first embodiment. (The same applies to the following embodiments). When the magnet 2a is magnetized after being integrally formed with the first cylindrical yoke 4a by injection molding, the axial direction of the first cylindrical yoke 4a is compared with that in FIG. 3 (b). Since the length is short (that is, almost the same as the axial length of magnet 2a), it can be easily magnetized.

In particular, in the case of a fuel pump, the pump portion 20 is required in the axial direction and the second cylindrical yoke 5a is longer in the axial direction than in the case of the DC motor, so that this effect is remarkable.

FIG. 3 (b) shows that the second cylindrical yoke 5b forms a magnetic circuit with the position corresponding to the magnet 2b (ie, the magnet 2b and the first cylindrical yoke 4b). Position) covers a part of the outer periphery of the first cylindrical yoke 4b.

With this configuration, the second cylindrical yoke 5b only needs to be arranged in an area necessary for the configuration of the magnetic circuit, and the entire outer periphery of the fuel pump can be reduced.

Also, as compared with the case of FIG. 3 (a), after the first cylindrical yoke 4b and the second cylindrical yoke 5b are press-fitted, the first cylindrical yoke 4b and the second cylindrical yoke 5b are fixed. It is easy to weld both for strengthening.

In the case of FIG. 3 (b), the first cylindrical yoke 4b includes a bearing holder 12 (see FIG. 1), an inlet housing 21 (see FIG. 1), and an outlet housing 23 (see FIG. 1). (See Fig. 1).

Similarly to the conventional example, the magnet 2b, which is shorter than the first cylindrical yoke 4b by about half or less in the axial direction, is substantially at the center of the first cylindrical yoke 4b in the axial direction. Are located in

Therefore, the magnet 2b is inserted into and fixed to the first cylindrical yoke 4b after molding, or a through hole (not shown) is provided on the side surface of the first cylindrical yoke 4b as in the conventional example. From the manufacturing efficiency, it is preferable to integrally form the magnet 2b on the inner periphery of the first cylindrical yoke 4b from the side surface of the cylindrical yoke 4b through the through hole.

Embodiment 3.

Hereinafter, a third embodiment of the present invention will be described. The third embodiment is a modification of the magnet and the first cylindrical yoke in the fuel pump described in the first and second embodiments. In each case, the magnet is integrated with the first cylindrical yoke by injection molding. It is a molded example.

FIG. 4 is a cross-sectional view schematically showing a magnet and a first cylindrical yoke of a DC motor-type fuel pump according to Embodiment 3 of the present invention, and FIG. 4 (a) is a tapered magnet. Fig. 4 (b) shows an example of fixing to the first cylindrical yoke at both ends of the magnet, Fig. 4 (c) shows an example of providing a projection on the end surface of the first cylindrical yoke, and Fig. 4 ( d) is a diagram showing only the yoke in FIG. 4 (c). In FIG. 4 (a), the inner peripheral surface of the first cylindrical yoke 4c has a tapered shape, and the first cylindrical yoke 4c has a first cylindrical yoke 4c formed by a rib 40c provided at an end of the magnet 2c. Since the lower end of the work 4c is covered, it is possible to prevent the magnet 2c from moving in the axial direction.

In Fig. 4 (b), the ribs at both ends of the magnet 2d integrated by injection molding cover both ends of the first cylindrical yoke 4d, so that the magnet 2d moves in the axial direction. Prevent, can.

In the case of FIG. 4 (c), a convex shape 50e is provided on the upper end surface of the first cylindrical yoke 4e as shown in FIG. 4 (d), and the magnet is integrated by injection molding. 2 e covers both ends of the first cylindrical yoke 4 e, The axial movement and rotation of the cut 2 e can be prevented. The same operation and effect can be obtained even if the convex shape 50e of the first cylindrical yoke 4e is concave. Embodiment 4.

Hereinafter, a fourth embodiment of the present invention will be described. Embodiment 4 is a modification of the fuel pump described in Embodiments 1 to 3 for preventing rotation of the magnet.

FIG. 5 is a simplified view of a magnet and a bearing holder of a DC motor fuel pump according to Embodiment 4 of the present invention. FIG. 5 (a) shows a cylindrical magnet bearing holder. Fig. 5 (b) is a sectional view showing the magnet, bearing holder and yoke of Fig. 5 (a), and Fig. 5 (b) is a cross-sectional view showing the magnet, bearing holder, and yoke of Fig. 5 (a). (C) is an example in the case where the magnet end face is corrugated, and FIGS. 5 (d) to (g) are examples in which the magnet end face is provided with concave portions and convex portions.

FIG. 5 (b) shows an example of a cylindrical yoke made of one member for convenience of description, but the cylindrical yoke and the first cylindrical yoke are similar to those in the first to third embodiments. It may be a cylindrical yoke composed of two members of a two cylindrical yoke.

In Fig. 5 (a), both the bearing holder 12f and the magnet 2f have flat end faces. As shown in Fig. 5 (b), the magnet 2 has both end faces. Of the yoke 3 f (that is, a protrusion formed radially in the inner circumference of the end of the yoke 3 f on the pump portion 20 side) 5 O f and the bearing holder 12 f.

The bearing holder 1 2 f houses the brush 9 of the DC motor (see Fig. 1), the bearing 8 of the armature 6 (see Fig. 1) (see Fig. 1), etc., and discharges the pressurized fuel 1 2a (see Fig. 1) is formed, and is always provided in the DC motor fuel pump. it can. In the case of Fig. 5 (c), the end faces of the bearing holder 12g and the magnet 2g are corrugated, and the rotation of the magnet 2f can be stopped by engaging these corrugated parts with each other. it can.

In Fig. 5 (d), a concave portion 70h is provided on the end surface of the bearing holder 12h, and a convex portion 60h is provided on the end surface of the magnet 2h. These concave portions and convex portions are alternated. The rotation of the magnet 2h can be stopped by engaging with. In Fig. 5 (e), a projection 61k is provided on the end face of the bearing holder 12k, and a recess 71k is provided on the end face of the magnet 2k. By the engagement, the rotation of the magnet 2k can be stopped. In Fig. 5 (f), the end face of the bearing holder 12m is provided with a concave portion 72m having panel properties in the circumferential direction, the magnet 2m is provided with a convex portion 62m, and the concave portion and the convex portion are provided. The rotation of the magnet 2 m can be stopped by the parts being engaged with each other.

In FIG. 5 (g), the bearing holder 12n is provided with a convex portion 73h having a panel characteristic in the circumferential direction, and the magnet 2η is provided with a concave portion 63n, and the concave portion and the convex portion are provided. By engaging with each other, the rotation of the magnet 2 m can be stopped.

Further, since the concave portion 72 m in the case of FIG. 5 (f) or the convex portion 73 h in the case of FIG. 5 (g) has a paneling property, FIG. 5 (d) or FIG. Compared to the case of Fig. (E), the magnet and the bearing holder can be engaged without interruption.

Note that, for example, the reason why the recess 72 m of the bearing holder 12 m has a spring property will be described. The concave part 72 m of the bearing holder 12 m has an insertion part (trapezoidal part) whose opening into which the convex part 62 2 m of the magnet is inserted is narrower than the convex part 62 2 of the magnet 2 m. A pair of protrusions protruding on both sides of the insertion portion, and a slit provided between the protrusion and a side portion of the bearing holder 12 m. It is composed of When the convex portion 62m of the magnet 2m is inserted into the concave portion 72m of the bearing holder 12m, the opening of the inserted portion is narrower than the concave portion 72m, so that the pair of protrusions is elastically deformed toward the slit side (that is, In this state, the magnet 2m and the bearing holder 12m are positioned.

When the magnet 2h or the magnet 2m is molded by injection molding, the protrusion of the magnet 2h or the magnet 2m in Fig. 5 (d) or Fig. 5 (f) is the gate part formed at the time of molding. The use of is preferred because gate processing is not required. In this case, the gate has a diameter or square of about 1 to 2.6 mm, and has a columnar or prismatic shape with a height of about lmm. Industrial applicability

INDUSTRIAL APPLICABILITY The present invention is useful for realizing a DC motor type fuel pump that has a high degree of freedom in magnetic circuit configuration and can easily magnetize a magnet with a small magnetizing device.

Claims

The scope of the claims

1. A DC motor fuel pump that boosts and outputs fuel at a pump section fixed to the yoke of the motor section in accordance with the driving of the DC motor of the motor section, wherein the yoke is formed of a rare earth ring. And a second cylindrical yoke provided on the outer periphery of the first cylindrical yoke at a position corresponding to the magnet. DC motor fuel pump.

2. The direct current motor-driven fuel pump according to claim 1, wherein the magnet is formed by injection molding, and a gate portion is provided on an end face of the magnet.

3. The magnet has a convex or concave portion provided on an end face thereof, and the convex or concave portion engages with a concave or convex portion of another member fixed to the yoke. Item 1. A DC motor fuel pump according to item 1.

4. The direct current motor type fuel pump according to claim 3, wherein the convex portion of the magnet is a gate portion of injection molding.

5. The direct current motor type fuel pump according to claim 1, wherein at least one end surface of the first cylindrical yoke and the magnet is a same surface.

6. The direct current motor type fuel pump according to claim 1, wherein an axial length of the first cylindrical yoke is substantially equal to an axial length of the magnet.

7. The direct current motor type fuel pump according to claim 1, wherein the magnet is formed by injection molding, and the thickness of the first cylindrical yoke is 3 mm or less.