Fuel pump and manufacturing method thereof

Abstract

In a fuel pump according to the present invention, an intermediate member 39 is formed from synthetic resin injection-molded from the first bearing side end portion 39a side toward the second bearing side end portion 39b side thereof. Thus, foreign matter adhering to the inner peripheral surface of a magnet 37 and the outer peripheral surface of a rotor shaft 38 can be prevented from mixing into the first bearing side end portion 39a of the intermediate member 39 made from synthetic resin in a rotor 36 of a motor portion 30.

Description

[Technical Field]

[0001] The present invention relates to a fuel pump that primarily supplies fuel to a fuel injection valve of an engine, and in particular to an improved fuel pump in which a motor section and a pump section driven by the motor section are housed within a housing, the rotor of the motor section comprising a cylindrical magnet, a rotor shaft that passes through the center of the magnet and causes first and second support shaft sections at both ends to protrude outside the magnet, and an intermediate member made of synthetic resin that is interposed between the magnet and the rotor shaft and connects the magnet and the rotor shaft to each other, the first support shaft section being rotatably supported via a first bearing on a pump case that is fixed to one end of the housing and rotatably houses an impeller, and is connected to the impeller, while the second support shaft section is rotatably supported via a second bearing on a cover member that is fixed to the other end of the housing, and one end of the intermediate member on the first bearing side is rotatably and slidably supported on the end face of the first bearing via a thrust washer, and to a method of manufacturing the same. [Background technology]

[0002] Such a fuel pump is already known as disclosed in Patent Document 1. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2021-32398 Summary of the Invention [Problem to be solved by the invention]

[0004] In such a fuel pump, the rotor of the motor receives a thrust force toward the first bearing during rotation, causing one end of the intermediate member of the rotor to rotate and slide relative to the thrust washer. The thrust force is generated by the weight of the rotor itself and the magnetic force that the stator exerts on the rotor, etc.

[0005] In such a conventional fuel pump, when the one end of the synthetic resin intermediate member, i.e., the end on the first bearing side, was observed, it was found that foreign matter such as chips was mixed in at that end. When the first bearing side end of the intermediate member rotates and slides against the thrust washer, the foreign matter becomes exposed and peels off from the rotating sliding surface of the intermediate member, causing an increase in sliding resistance and uneven wear on the rotating sliding surface of the intermediate member, and there is a risk that the foreign matter may penetrate into other sliding parts of the fuel pump, causing an increase in sliding resistance and uneven wear.

[0006] However, it was discovered that the reason for the presence of foreign matter at the first bearing side end of the synthetic resin intermediate part is that, even though the rotor shaft and magnet were cleaned after finishing, foreign matter such as chips remained on the outer surface of the rotor shaft and the inner surface of the magnet.When the intermediate part was injection molded, the synthetic resin was injected from the second bearing side end of the intermediate part toward the first bearing side end, causing the synthetic resin to pick up the foreign matter and flow toward the first bearing side end of the intermediate part.

[0007] Therefore, the present invention has been made in consideration of such circumstances, and aims to provide a fuel pump in which foreign matter is prevented from being mixed in the first bearing side end of the synthetic resin intermediate member in the rotor of the motor section, as well as a method for manufacturing the same. [Means for solving the problem]

[0008] In order to achieve the above object, the present invention provides a fuel pump in which a motor section and a pump section driven by the motor section are accommodated within a housing, the rotor of the motor section comprises a cylindrical magnet, a rotor shaft that passes through the center of the magnet and causes first and second support shaft sections at both ends to protrude outside the magnet, and an intermediate member made of synthetic resin that is interposed between the magnet and the rotor shaft and connects the magnet and the rotor shaft to each other, the first support shaft section is rotatably supported via a first bearing on a pump case that is fixed to one end of the housing and rotatably houses an impeller, and is connected to the impeller, while the second support shaft section is rotatably supported via a second bearing on a cover member that is fixed to the other end of the housing, and one end of the intermediate member on the first bearing side is rotatably and slidably supported on the end face of the first bearing via a thrust washer, the first feature of which is that the intermediate member is made of synthetic resin that is injection molded from one end on the first bearing side to the other end.

[0009] In addition to the first feature, the present invention has a second feature in that a gate residue portion resulting from injection molding of the synthetic resin is left at one end of the intermediate member on the first bearing side.

[0010] Furthermore, in addition to the second feature, the present invention has a third feature in that a recess is provided on the surface of the intermediate member facing the thrust washer, and the gate remaining portion remains on the bottom surface of the recess.

[0011] Furthermore, in addition to the second feature, the present invention has a fourth feature in that the gate remaining portion remains on the side surface of one end of the intermediate member on the first bearing side.

[0012] Furthermore, the present invention is directed to a pump in which a motor section and a pump section driven by the motor section are accommodated within a housing, the rotor of the motor section comprising a cylindrical magnet, a rotor shaft that penetrates the center of the magnet and causes first and second support shaft sections at both ends to protrude outside the magnet, and an intermediate member made of synthetic resin that is interposed between the magnet and the rotor shaft and connects the magnet and the rotor shaft to each other, the first support shaft section being fixed to one end of the housing and rotatably supporting the impeller via a first bearing in a pump case that accommodates the impeller, and being connected to the impeller, while the second support shaft section In a manufacturing method for a fuel pump in which the intermediate member is rotatably supported via a second bearing on a cover member fixed to the other end of the housing, and one end of the intermediate member on the first bearing side is rotatably and slidably supported on the end face of the first bearing via a thrust washer, a fifth feature is that when the intermediate member is injection molded from synthetic resin, a cavity corresponding to the intermediate member and a gate opening to a part of the cavity corresponding to the one end of the intermediate member on the first bearing side are provided, and the synthetic resin is injected from the gate into the cavity, filling it, to mold the intermediate member.

[0013] Furthermore, in addition to the fifth feature, the present invention has a sixth feature in that a molding mold is formed by overlapping a movable mold that supports the first support shaft portion on a fixed mold that supports the magnet and the second support shaft portion, the fixed mold having a downstream cavity that corresponds to the main part of the intermediate member excluding one end portion on the first bearing side, and the movable mold having an upstream cavity that corresponds to one end portion of the intermediate member on the first bearing side and a gate that opens into the upstream cavity, and synthetic resin is injected from the gate to fill it sequentially from the upstream cavity to the downstream cavity to mold the intermediate member.

[0014] Furthermore, in addition to the sixth feature, the present invention has a seventh feature in that a large truncated cone chamfer is formed on the tip edge of the first support shaft portion of the rotor shaft, while a small truncated cone chamfer with a cone height smaller than the large chamfer is formed on the opening edge of a support hole provided in the movable mold for inserting the first support shaft portion. The support hole corresponds to a third support hole 57 in an embodiment of the present invention described below.

[0015] Furthermore, in addition to the seventh feature, the present invention has an eighth feature in that the cone angle of the large chamfer is set to less than 90°. [Effects of the Invention]

[0016] According to a first feature of the present invention, the intermediate member is made of synthetic resin that is injection-molded from its first bearing-side end toward its second bearing-side end, so that the first bearing-side end of the intermediate member is located upstream of the flow of the synthetic resin. Therefore, even if foreign matter adhering to the inner peripheral surface of the magnet or the outer peripheral surface of the rotor shaft is caught in the flow of the synthetic resin, it flows toward the second bearing-side end of the intermediate member along with the synthetic resin and does not become mixed in with the first bearing-side end of the intermediate member, which is located upstream. This prevents the foreign matter from being exposed or peeled off from the rotating sliding surface of the intermediate member during the rotational sliding between the first bearing-side end of the intermediate member and the thrust washer. This prevents the foreign matter from increasing the sliding resistance or causing uneven wear on the rotating sliding surface of the intermediate member, or from penetrating into other sliding parts of the fuel pump and causing increased sliding resistance or uneven wear.

[0017] According to the second feature of the present invention, a gate residue from the injection molding of synthetic resin is left at the first bearing side end of the intermediate member, so that by visually checking that the gate residue is present on the first support shaft side of the rotor shaft, it is possible to confirm that there is no error in the injection direction of the synthetic resin.

[0018] According to the third feature of the present invention, a recess is provided on the surface of the intermediate member facing the thrust washer, and the gate residual portion is left on the bottom surface of the recess.Therefore, when molding the intermediate member, the gate can be easily positioned without being obstructed by the magnet or rotor shaft, and the gate residual portion does not interfere with the thrust washer.

[0019] According to the fourth feature of the present invention, a gate residue is left on the side surface of the first bearing side end of the intermediate member, so that, as described above, when molding the intermediate member, the gate can be easily positioned without being obstructed by the magnet or rotor shaft, and the gate residue does not interfere with the thrust washer.

[0020] According to the fifth feature of the present invention, when molding an intermediate member from synthetic resin, a cavity corresponding to the intermediate member and a gate opening at a portion of the cavity corresponding to the first bearing side end of the intermediate member are provided in the molding mold, and synthetic resin is injected from the gate into the cavity and filled to mold the intermediate member.Therefore, during molding, foreign matter adhering to the inner surface of the magnet or the outer surface of the rotor shaft can be mixed into the flow of synthetic resin and flowed toward the second bearing side end of the intermediate member, thereby preventing the foreign matter from being mixed in at the first bearing side end of the intermediate member.

[0021] According to the sixth feature of the present invention, a molding mold is constructed by superimposing a movable mold that supports the first support shaft portion of the rotor shaft on a fixed mold that supports the magnet and the second support shaft portion of the rotor shaft, and the fixed mold is provided with a downstream cavity that corresponds to the main part of the intermediate member excluding the first bearing side end, and the movable mold is provided with an upstream cavity that corresponds to the first bearing side end of the intermediate member and a gate that opens into the upstream cavity, and by injecting synthetic resin from the gate and filling it sequentially from the upstream cavity to the downstream cavity to mold the intermediate member, it is possible to mold an intermediate member that does not have foreign matter mixed in at the first bearing side end, and after molding, the intermediate member can be easily removed from both molds by opening the space between the fixed mold and the movable mold.

[0022] According to the seventh feature of the present invention, a large truncated cone-shaped chamfer is formed on the tip edge of the first support shaft portion of the rotor shaft, while a small truncated cone-shaped chamfer with a cone height smaller than the large chamfer is formed on the opening edge of the support hole provided in the movable mold for inserting the first support shaft portion of the rotor shaft.The guiding action of these large and small chamfers makes it possible to easily insert the first support shaft portion of the rotor shaft into the support hole, and by making the chamfer on the opening edge of the support hole a small chamfer, the annular protrusion formed on the first bearing side end face of the intermediate member corresponding to the small chamfer becomes extremely small.Therefore, it is easily worn away by rotational sliding with the thrust washer while the rotor is rotating, and good contact with the thrust washer of the intermediate member can be achieved early on.

[0023] According to the eighth feature of the present invention, by setting the cone angle of the large truncated cone chamfer formed on the tip edge of the first support shaft portion of the rotor shaft to less than 90°, the first bearing side end of the rotor shaft can be more easily inserted into the support hole, while the cone height of the small chamfer formed on the opening edge of the support hole can be set smaller. [Brief explanation of the drawings]

[0024] [Figure 1] FIG. 1 is a vertical cross-sectional view of an entire fuel pump according to one embodiment of the present invention. [Figure 2] FIG. 2 is an enlarged cross-sectional view taken along line 2-2 of FIG. [Figure 3] FIG. 3 is a side view showing a modified example of the rotor in FIG. [Figure 4] FIG. 4 is an enlarged cross-sectional view taken along line 4-4 in FIG. [Figure 5] FIG. 5 is a vertical cross-sectional view of a mold and a molded product used in carrying out the manufacturing method of the rotor of the motor portion in FIG. [Explanation of symbols]

[0025] P······Fuel pump θ······· Cone angle of large and small chamfers H: Cone height of large chamfer h: Cone height of small chamfer 10. Housing 11 Cover member 20 Pump section 21 Pump case 24 Impeller 30 Motor section 36 Rotor 37 Magnet 38 Rotor shaft 38a...1st support shaft part 38b...Second support shaft part 39. Intermediate member 39a... First bearing side end of intermediate member 39b... Second bearing side end of intermediate member 46 Recess 47. Remaining gate 51... First bearing 52... Second bearing 53 Thrust washer 54...Molding mold 54a...Fixed type 54b...Movable type 57... Support hole (3rd support hole) 58...Upstream cavity 59 Downstream cavity 60 Gate 62 Large chamfer 63 Small chamfer DETAILED DESCRIPTION OF THE INVENTION

[0026] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings.

[0027] First, in Figures 1 and 2, the fuel pump P of the present invention is provided in the fuel supply system of an engine mounted on a vehicle, such as an automobile or motorcycle, and is used to pressurize fuel to the engine's fuel injection device, and is installed and fixed, for example, in the vehicle's fuel tank (not shown) in an upright position as shown in Figure 1.

[0028] To explain an example of a fuel pump P, it comprises a metal housing 10 formed in an approximately cylindrical shape with both the upper and lower ends open, a synthetic resin cover member 11 that closes the open upper end of the housing 10, a pump section 20 fitted into the lower inner periphery of the housing 10, and a motor section 30 that is positioned adjacent to the upper side of the pump section 20 and fitted into the inner periphery of the middle part of the housing 10.

[0029] Next, the pump section 20 and the motor section 30 will be described in detail in order.

[0030] A conventionally well-known cascade pump is used as the pump section 20, and it includes, for example, a pump case 21 that is fitted and fixed to the inner periphery of the lower end of the housing 10 so as to close the open end on the lower side of the housing 10, and a disk-shaped impeller 24 that is rotatably and slidably housed in a pump chamber 25 within the pump case 21. A first support shaft portion 38a of a rotor shaft 38 (described later) is removably inserted and connected to a connecting hole 24a in the center of the impeller 24, so that the impeller 24 is driven by the rotor shaft 38. The rotation axis X of the rotor shaft 38 coincides with the rotation axis of the impeller 24.

[0031] The pump section 20 is not limited to a cascade pump, and other pumps may also be used.

[0032] The pump case 21 is divided into a disk-shaped pump case main body 22 and a disk-shaped pump case cover 23 adjacent to the underside of the pump case main body 22, and the pump chamber 25 is defined between the opposing surfaces of the two 22, 23, in which the impeller 24 is accommodated in a rotatable and slidable manner.

[0033] Pump case cover 23 is provided with suction hole 26 opening toward the fuel tank, and pump case main body 22 is provided with discharge hole 27 opening toward motor section 30. Pump case cover 23 is also provided with vent hole 28 for discharging air bubbles generated in pump chamber 25 toward the fuel tank. In pump section 20, fuel in the fuel tank is sucked in through suction hole 26 by rotation of impeller 24 driven by rotor shaft 38, which will be described later, and pressurized in pump chamber 25, and then discharged from discharge hole 27 into motor section 30.

[0034] Furthermore, a fuel outlet tube 11a is provided on the upper surface of the cover member 11 so as to protrude upward and discharge the pressurized fuel discharged from the discharge hole 27 into the motor section 30 to the fuel injection device side of the engine via an external pipe. A check valve 41 is provided inside the fuel outlet tube 11a to allow fuel to flow in only one direction, from inside the motor section 30 to the external pipe side.

[0035] A first bearing 51 made of a plain bearing is fitted (e.g., press-fit) into the center hole of the pump case body 22. The first bearing 51 is formed into a cylindrical shape by sintering metal powder, for example, nickel silver powder, which has been compacted. A second bearing 52, also made of a plain bearing, is fitted into the center of the inner wall of the cover member 11. These first and second bearings 51, 52 are arranged coaxially, and the first and second bearings 51, 52 rotatably support both ends of the rotor shaft 38, which will be described later, i.e., first and second support shaft portions 38a, 38b. The tip of the first support shaft portion 38a, which protrudes downward from the first bearing 51, has a partially circular cross section and is non-rotatably fitted into a connecting hole 24a, which also has a partially circular cross section, in the center of the impeller 24, thereby enabling the rotor shaft 38 to drive the impeller 24. Furthermore, the flat connecting surface at the tip of the first support shaft portion 38a, which has a partially circular cross section, is indicated by the symbol 49, and this connecting surface 49 abuts against the flat surface on the inner periphery of the connecting hole 24a of the impeller 24, thereby connecting the first support shaft portion 38a and the impeller 24 so that they cannot rotate relative to each other.

[0036] Next, we will explain the motor unit 30. A brushless motor is used as the motor unit 30. That is, the motor unit 30 is composed of a stator 31 made up of a stator core 32 whose outer periphery is fixed (for example, press-fitted) to the housing 10, an insulator 33 made of synthetic resin that is fixed to the stator core 32 and covers at least both ends of the stator core 32, and a coil 34 wound around the stator core 32 via the insulator 33, and a rotor 36 with a magnet that cooperates with the stator 31 to output a rotational force.

[0037] The rotor 36 is made up of a cylindrical magnet 37, the rotor shaft 38 placed at the center of the magnet 37, and an intermediate member 39 made of synthetic resin that connects the magnet 37 and the rotor shaft 38 together by injecting and filling synthetic resin between the magnet 37 and the rotor shaft 38. A synthetic resin material with excellent wear resistance, such as polyacetal POM, is selected for the intermediate member 39. The magnet 37 has N and S poles arranged alternately in the circumferential direction.

[0038] Furthermore, the intermediate member 39 will be described in detail.

[0039] A lower end 39a of the intermediate member 39 protruding toward the first bearing 51 side from the magnet 37 (hereinafter referred to as the first bearing side end 39a) comprises a flange 43 that is in close contact with the lower end surface of the magnet 37 and a thrust cylindrical portion 44 that protrudes from the outer end surface of the flange 43, and the thrust cylindrical portion 44 is supported on the end surface of the first bearing 51 via a thrust washer 53. The thrust washer 53 is made of metal, for example, a stainless steel plate.

[0040] In this embodiment, a downward thrust force due to the total weight of the rotor 36 and the magnetic force of the stator core 32 attracting the magnet 37 toward the first bearing 51 acts on the rotor 36, so that while the rotor 36 is rotating, the thrust tube portion 44 of the intermediate member 39 rotates and slides against the thrust washer 53.

[0041] On the other hand, the upper end 39b of the intermediate member 39 on the second bearing 52 side is flange-shaped and is in close contact with the upper end surface of the magnet 37. Since the rotor 36 receives a downward thrust force as described above, the upper end 39b of the intermediate member 39 is slightly spaced apart from the end surface of the second bearing 52 even while the rotor 36 is rotating.

[0042] Intermediate member 39 holds magnet 37 in the axial direction between its two ends 39a, 39b, strengthening the bonding force between magnet 37 and intermediate member 39. In addition, an annular groove 45 into which intermediate member 39 bites is provided on the outer circumferential surface of the rotor shaft, strengthening the bonding force between rotor shaft 38 and intermediate member 39.

[0043] As clearly shown in the partially enlarged view of FIG. 1 and FIG. 2, the end face of the flange 43 is provided with a plurality of (three in the illustrated example) recesses 46 arranged at equal intervals in the circumferential direction, and a gate remaining portion 47 protruding from the bottom surface of one of the recesses 46 remains within it. The height of the gate remaining portion 47 is set to be equal to or less than the depth of the recess 46. Therefore, the gate remaining portion 47 does not protrude below the end face of the flange 43. In this case, the flange 43 is given a relatively large thickness in order to provide the recess 46 with sufficient depth to make it easier to leave the gate remaining portion 47. Furthermore, the plurality of recesses 46 are arranged at equal intervals in the circumferential direction of the flange 43 in order to achieve rotational balance of the rotor 36.

[0044] As described above, the presence of the gate residual portion 47 on the flange 43 of the first bearing-side end portion 39a in the synthetic resin intermediate member 39 means that, during injection molding of the intermediate member 39, the synthetic resin injected from the gate corresponding to the gate residual portion 47 flows from the first bearing-side end portion 39a toward the second bearing-side end portion 39b. Therefore, even if foreign matter such as chips adhering to the inner peripheral surface of the magnet 37 or the outer peripheral surface of the rotor shaft 38 gets mixed in with the flow of synthetic resin, it will be flowed toward the second bearing-side end portion 39b of the intermediate member 39, and therefore it is possible to prevent the foreign matter from getting mixed in with the first bearing-side end portion 39a of the intermediate member 39. This prevents the foreign matter from becoming exposed and peeling off from the rotating sliding surface of the intermediate member 39, i.e., the end face of the thrust cylindrical portion 44, during the rotational sliding motion between the first bearing side end portion 39a of the intermediate member 39 and the thrust washer 53, thereby causing an increase in the sliding resistance or uneven wear of the rotating sliding surface of the thrust cylindrical portion 44, or from penetrating into other sliding portions of the fuel pump and causing an increase in the sliding resistance or uneven wear.

[0045] Furthermore, by visually confirming that the gate remaining portion 47 is present on the side of the rotor shaft 38, namely, the first support shaft portion 38a having the connecting surface 49, it is possible to confirm that there is no error in the injection direction of the synthetic resin during injection molding of the intermediate member 39.

[0046] Furthermore, a gate residue 47 protruding from the bottom surface of a recess 46 formed on the end face of the flange 43 is left within the recess 46, and the height of the gate residue 47 is set to be less than the depth of the recess 46. Therefore, when molding the intermediate member 39, the gate corresponding to the gate residue 47 can be easily positioned without being obstructed by the magnet 37 or rotor shaft 38, and the gate residue 47 can be prevented from interfering with the thrust washer 53.

[0047] Furthermore, although the foreign matter mixed in with the flow of synthetic resin will be present at the second bearing side end 39b of the intermediate member 39, the second bearing side end 39b is separated from the second bearing 52 and does not come into contact with it, so there will be no inconvenience such as the foreign matter peeling off from the second bearing side end 39b.

[0048] 3 and 4 show a modified example of the rotor 36. This modified example differs from the above-described embodiment in the arrangement of the gate remaining portion 47. That is, a flat surface 48 is formed on one side of the flange 43 of the first bearing side end portion 39a of the synthetic resin intermediate member 39, and the gate remaining portion 47 remains in the center of the flat surface 48. The height of the gate remaining portion 47 is set so that it does not protrude from the outer peripheral surface of the flange 43. In addition, in FIGS. 3 and 4, parts corresponding to those in the above-described embodiment are given the same reference numerals, and duplicate explanations will be omitted.

[0049] Next, a method for manufacturing the rotor 36 in the above embodiment will be described with reference to Fig. 5. In Fig. 5, parts corresponding to those in Fig. 1 of the above embodiment will be given the same reference numerals, and duplicated explanations will be omitted.

[0050] The molding die 54 used to implement this manufacturing method is composed of a fixed die 54a that supports the magnet 37 and the second support shaft portion 38b of the rotor shaft 38, and a movable die 54b that supports the first support shaft portion 38a of the rotor shaft 38.

[0051] The fixed mold 54a is provided with a first support hole 55 into which the magnet 37 is inserted and a second support hole 56 into which the second support shaft portion 38b of the rotor shaft 38 is inserted, and a downstream cavity 59 corresponding to the main part of the intermediate member 39 excluding the first bearing side end portion 39a is defined between the magnet 37 and the rotor shaft 38.

[0052] The movable mold 54b is provided with a third support hole 57 into which the first support shaft portion 38a of the rotor shaft 38 is inserted, an upstream cavity 58 corresponding to the first bearing side end portion 39a of the intermediate member 39, a gate 60 that opens into the portion of the upstream cavity 58 that corresponds to the flange 43 of the first bearing side end portion 39a, and a runner 61 extending upward from the gate 60.

[0053] After the movable mold 54b is placed on top of the fixed mold 54a, synthetic resin is injected from the runner 61 through the gate 60 into the upstream cavity 58, and is sequentially filled from the upstream cavity 58 to the downstream cavity 59 to form the intermediate member 39. During this process, foreign matter adhering to the inner peripheral surface of the magnet 37 or the outer peripheral surface of the rotor shaft 38 only mixes with the synthetic resin filled in the downstream cavity 59 and does not flow back into the upstream cavity 58. Therefore, the foreign matter does not get mixed in with the first bearing side end 39a of the intermediate member 39 formed in the upstream cavity 58.

[0054] A large chamfer 62 having a truncated cone shape is formed on the end edge of the first support shaft portion 38a of the rotor shaft 38, while a small chamfer 63 is formed on the opening end edge of the third support hole 57 into which the first support shaft portion 38a of the rotor shaft 38 is inserted. Here, the cone height h of the small chamfer 63 is smaller than the cone height H of the large chamfer 62.

[0055] When the fixed mold 54 a and the movable mold 54 b are overlapped, the first support shaft portion 38 a of the rotor shaft 38 can be easily inserted into the third support hole 57 due to the guiding action of the large chamfer 62 and the small chamfer 63 .

[0056] Furthermore, by chamfering the opening edge of the third support hole 57 with a small chamfer 63, the annular protrusion 64 formed on the end face of the first bearing side end 39a of the intermediate member 39 corresponding to the small chamfer 63 becomes extremely small, so that it easily wears away due to rotational sliding with the thrust washer 53 while the rotor 36 is rotating, and a stable contact state with the thrust washer 53 of the intermediate member 39 can be obtained early on.

[0057] Furthermore, by setting the cone angle θ of the large chamfer 62 to less than 90°, the first support shaft portion 38a of the rotor shaft 38 can be more easily inserted into the third support hole 57 of the movable mold 54b, while the cone height of the small chamfer 63 formed at the opening edge of the third support hole 57 can be set smaller.

[0058] Although the embodiments of the present invention have been described above, the present invention is not limited to these, and various design modifications are possible within the scope of the gist of the present invention.

Claims

1. A motor section (30) and a pump section (20) driven by the motor section (30) are accommodated in a housing (10), and the rotor (36) of the motor section (30) comprises a cylindrical magnet (37), a rotor shaft (38) that penetrates the center of the magnet (37) and causes first and second support shaft sections (38a, 38b) at both ends to project outside the magnet (37), and an intermediate member (39) made of synthetic resin that is interposed between the magnet (37) and the rotor shaft (38) and connects the magnet (37) and the rotor shaft (38) to each other, and the first support shaft section (38a) is A fuel pump in which the second support shaft portion (38b) is rotatably supported via a first bearing (51) on a pump case (21) fixed to one end of a housing (10) and rotatably accommodating an impeller (24) and is connected to the impeller (24), while the second support shaft portion (38b) is rotatably supported via a second bearing (52) on a cover member (11) fixed to the other end of the housing (10), and one end (39a) of the intermediate member (39) on the first bearing (51) side is rotatably and slidably supported on an end surface of the first bearing (51) via a thrust washer (53), The intermediate member (39) is made of synthetic resin that is injection molded from one end (39a) on the first bearing (51) side to the other end (39b), A gate residue (47) resulting from injection molding of the synthetic resin is left at one end (39a) of the intermediate member (39) on the side of the first bearing (51). A fuel pump characterized by:

2. 2. The fuel pump according to claim 1, A fuel pump characterized in that a recess (46) is provided on a surface of the intermediate member (39) facing the thrust washer (53), and the gate remaining portion (47) remains on a bottom surface of the recess (46).

3. 2. The fuel pump according to claim 1, The fuel pump is characterized in that the gate remaining portion (47) remains on a side surface of one end (39a) of the intermediate member (39) on the side of the first bearing (51).

4. A motor section (30) and a pump section (20) driven by the motor section (30) are accommodated in a housing (10), and the rotor (36) of the motor section (30) comprises a cylindrical magnet (37), a rotor shaft (38) that penetrates the center of the magnet (37) and causes first and second support shaft sections (38a, 38b) at both ends to protrude outside the magnet (37), and an intermediate member (39) made of synthetic resin that is interposed between the magnet (37) and the rotor shaft (38) and connects the magnet (37) and the rotor shaft (38) to each other, and the first support shaft section (38a) is attached to the housing. a pump case (21) fixed to one end of a housing (10) and rotatably accommodating an impeller (24) therein, the pump case (21) being rotatably supported via a first bearing (51) and connected to the impeller (24), while the second support shaft portion (38b) being rotatably supported via a second bearing (52) on a cover member (11) fixed to the other end of the housing (10), and one end (39a) of the intermediate member (39) on the first bearing (51) side being rotatably and slidably supported on an end face of the first bearing (51) via a thrust washer (53), A method for manufacturing a fuel pump, characterized in that, when injection molding the intermediate member (39) from synthetic resin, a molding die (54) is provided with cavities (58, 59) corresponding to the intermediate member (39) and gates (60) opening into the cavities (58, 59) at portions of the intermediate member (39) corresponding to one end (39 a) on the first bearing (51) side, and synthetic resin is injected from the gates (60) into the cavities (58, 59) to fill them and mold the intermediate member (39).

5. 5. The method for manufacturing a fuel pump according to claim 4, a fixed die (54a) supporting the magnet (37) and the second support shaft portion (38b) is overlapped with a movable die (54b) supporting the first support shaft portion (38a) to form a molding die (54); the fixed die (54a) is provided with a downstream cavity (59) corresponding to a main portion of the intermediate member (39) excluding one end (39a) on the first bearing (51) side; the movable die (54b) is provided with an upstream cavity (58) corresponding to the one end (39a) of the intermediate member (39) and a gate (60) opening into the upstream cavity (58); and a synthetic resin is injected from the gate (60) to fill the upstream cavity (58) sequentially from the upstream cavity (58) to the downstream cavity (59) to mold the intermediate member (39).

6. 6. The method for manufacturing a fuel pump according to claim 5, A method for manufacturing a fuel pump, characterized in that a large truncated cone chamfer (62) is formed on the tip edge of the first support shaft portion (38a) of the rotor shaft (38), while a small truncated cone chamfer (63) having a cone height smaller than the large chamfer (62) is formed on the opening edge of a support hole (57) provided in the movable mold (54b) to fit the first support shaft portion (38a).

7. 7. The method for manufacturing a fuel pump according to claim 6, The method for manufacturing a fuel pump is characterized in that the cone angle (θ) of the large chamfer (62) is set to less than 90°.

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