Liquid pump and method of manufacturing liquid pump

Abstract

To provide a liquid pump that can prevent intrusion of rust into fuel which is supplied to an internal combustion engine, and a method of manufacturing the liquid pump.SOLUTION: A fuel pump 1 comprises: a pump unit P; and a motor M which drives the pump unit P. The pump motor M comprises: a stator 10; a rotor 12 which is rotatably provided on the radially inner side of the stator 10; and a flow passage 30 which is formed between the stator 10 and the rotor 12, and in which fuel pumped by the pump part P flows. A plated membrane created by electrolytic plating is formed on an external peripheral surface 14c and an internal peripheral surface 14d, which are exposed to the outside of a stator core 14 with a plurality of coils 17 and a motor cover 18 attached to the stator core 14 of the stator 10. A mark of an electrode which is formed in application of electrolytic plating is formed on the external peripheral surface 14c of the stator core 14.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a liquid pump and a method for manufacturing a liquid pump. [Background technology]

[0002] An example of a liquid pump is a fuel pump for vehicles such as motorcycles and four-wheeled vehicles. This type of fuel pump is a so-called in-tank type that is disposed inside a fuel tank and submerged in fuel. The fuel pump has a pump motor and a pump unit disposed inside a cylindrical housing case. The fuel pump pressurizes the fuel in the fuel tank in the pump unit by rotating the pump unit with the pump motor. The pressurized fuel passes through a flow path formed in the fuel pump and is supplied to the internal combustion engine from a discharge port.

[0003] In the above fuel pump, for example, there is known a fuel pump in which a tin plating film (Sn plating film) is formed by electrolytic plating on a stator core in a state where the stator core is provided with an insulator, a motor cover, etc. By forming a tin plating film on the stator core, it is possible to ensure the corrosion resistance of the stator core (for example, see Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2015-83828 A Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, when electrolytic plating is performed on a stator core, for example, an electrode is abutted against the outer peripheral surface of the stator core. In this case, it is difficult to form a plating film at the portion of the outer peripheral surface of the stator core where the electrode is abutted, and a mark is left. It is considered that rust will occur at this mark. For example, in a fuel pump, when a flow path through which fuel flows is formed between a housing case provided on the outer peripheral surface side of the stator and the outer peripheral surface of the stator core, fuel is supplied to an internal combustion engine along the outer peripheral surface of the stator core. For this reason, there is a concern that rust generated on the outer peripheral surface of the stator core will be mixed into the fuel.

[0006] Therefore, the present invention provides a liquid pump that can prevent rust from being mixed into fuel supplied to an internal combustion engine, for example, and a method for manufacturing the liquid pump. [Means for solving the problem]

[0007] In order to solve the above problems, a first aspect of the present invention comprises a pump section that pumps up a liquid, and a pump motor that drives the pump section, wherein the pump motor comprises a stator, a rotor that is rotatably arranged radially inside the stator and connected to the pump section, and a flow path formed between the stator and the rotor and through which the liquid pumped up by the pump section flows, and the stator comprises a stator core in which a plurality of electromagnetic steel plates are laminated, a plurality of coils wound around the stator core, and a motor cover that protects the plurality of coils, wherein when the plurality of coils and the motor cover are attached to the stator core, a plating coating is formed by applying electrolytic plating to an exposed portion exposed to the outside of the stator core, and an electrode abutment mark caused by an electrode abutting when the electrolytic plating is applied is formed on the outer peripheral surface of the stator core in the exposed portion.

[0008] This configuration can prevent the outer peripheral surface of the stator core, on which the electrode marks are formed, from becoming a flow path. There is a possibility that the electrode marks will not form a plating film and rust will occur on them. Therefore, by configuring as described above, even when the liquid pump is used as a fuel pump that supplies fuel to an internal combustion engine, for example, it is possible to prevent rust from being mixed into the fuel supplied to the internal combustion engine.

[0009] In a second aspect of the present invention, the liquid pump of the first aspect may be provided with a housing case having a cylindrical portion, the pump portion being accommodated within the housing case, and the outer peripheral surface of the stator being fitted to the inner peripheral surface of the cylindrical portion.

[0010] With this configuration, a flow path through which liquid can flow reliably can be formed between the stator and the rotor.

[0011] In a third aspect of the present invention, in the liquid pump of the second aspect, the housing case may have a radial dimension larger than the outer circumferential surface of the stator core.

[0012] This configuration can prevent the plating film from coming into contact with the inner peripheral surface of the housing case and peeling off from the outer peripheral surface of the stator core.

[0013] In a fourth aspect of the present invention, in a method for manufacturing a liquid pump comprising a pump section that pumps up liquid and a pump motor that drives the pump section, the pump motor comprising a stator, a rotor that is rotatably arranged radially inside the stator and connected to the pump section, and a flow path formed between the stator and the rotor and through which the liquid pumped up by the pump section flows, the stator is formed by a lamination process of stacking a plurality of electromagnetic steel plates to form a stator core, a winding process of winding a plurality of coils around the stator core, a molding process of forming a motor cover that protects the plurality of coils, and, after the molding process, a plating process of abutting an electrode against the outer peripheral surface of the stator core and applying electrolytic plating to form a plating coating on exposed portions exposed to the outside of the stator core.

[0014] With this method, even if electrode marks are formed on the outer peripheral surface of the stator core, the outer peripheral surface of the stator core can be prevented from becoming a flow path. There is a possibility that a plating film will not be formed on the electrode marks, causing rust. However, since the outer peripheral surface of the stator core is not used as a flow path, it is possible to prevent rust from being mixed into the fuel supplied to the internal combustion engine, for example, even when the liquid pump is used as a fuel pump that supplies fuel to the internal combustion engine. In addition, it is possible to prevent a plating film from being formed on the outer peripheral surface of the stator core with gaps being generated between the multiple electromagnetic steel sheets, which prevents a plating film from being formed between the electromagnetic steel sheets, causing iron loss and deteriorating motor performance. Effect of the Invention

[0015] According to the present invention, for example, it is possible to prevent rust from being mixed into fuel supplied to an internal combustion engine. [Brief description of the drawings]

[0016] [Figure 1] 1 is a perspective side view of a fuel pump according to an embodiment of the present invention; [Diagram 2]2 is a side view of the fuel pump of FIG. 1 with a housing case and a pump motor partially cut away. [Diagram 3] 2 is a perspective view showing a stator core of a pump motor provided in the fuel pump according to the embodiment of the present invention; FIG. [Figure 4] 4 is a perspective view showing a state in which an insulator and a plurality of coils are provided on the stator core of FIG. 3. [Diagram 5] 5 is a perspective view showing a state in which the stator core in FIG. 4 is formed into a primary molded product. [Figure 6] 6 is a perspective view showing a state in which the primary molded product in FIG. 5 is formed into a secondary molded product. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Next, an embodiment of the present invention will be described with reference to the drawings.

[0018] <Fuel pump> Fig. 1 is a perspective side view of the fuel pump 1. Fig. 2 is a side view of the fuel pump of Fig. 1, with a housing case 6 and a pump motor M partially cut away. 1 and 2, the fuel pump 1 is an in-tank type that is disposed submerged in fuel inside a fuel tank of a vehicle such as an automobile or motorcycle. The fuel pump 1 pumps fuel from inside the fuel tank and pumps it to an internal combustion engine 2. In the embodiment, an example will be described in which the fuel pump 1 is disposed in the vertical direction inside the fuel tank. However, the present invention is not limited to this, and the direction in which the fuel pump 1 is disposed can be selected arbitrarily.

[0019] The fuel pump 1 includes a pump motor M, an outlet cover 4 provided on the pump motor M, a pump section P arranged on the opposite side of the outlet cover 4 with the pump motor M in between, and a housing case 6 that houses the pump motor M, the outlet cover 4, and the pump section P. In the fuel pump 1, the pump motor M, the outlet cover 4, the pump section P, and the housing case 6 are provided on the same axis O. Hereinafter, the axis O of the fuel pump 1 may be simply referred to as the "axis O", the radial direction about the axis O may be simply referred to as the "radial direction", and the circumferential direction about the axis O may be simply referred to as the "circumferential direction".

[0020] <Pump motor> Fig. 3 is a perspective view showing a stator core 14 of the pump motor M. Fig. 4 is a perspective view showing a state in which an insulator 16 and a plurality of coils 17 are attached to the stator core 14 of Fig. 3. 2 to 4, the pump motor M is, for example, a so-called brushless motor that does not require brushes when supplying power to the stator 10. The pump motor M includes a stator 10 formed in a cylindrical shape, and a rotor 12 disposed radially inside the stator 10 and rotatably provided with respect to the stator 10.

[0021] The stator 10 comprises a cylindrical stator core 14 formed by stacking a plurality of electromagnetic steel plates 15, an insulator 16 covering teeth 14a of the stator core 14, a plurality of coils 17 wound around the teeth 14a via the insulator 16, and a motor cover 18 protecting the plurality of coils 17.

[0022] The stator core 14 is formed by stacking a plurality of annular electromagnetic steel sheets 15 in the direction of the axis O. The stator core 14 has a plurality of teeth 14a protruding radially inward. The stator core 14 has slots 14b formed between the teeth 14a adjacent to each other in the circumferential direction.

[0023] The insulator 16 is, for example, molded with resin so as to cover the teeth 14a of the stator core 14. The resin for molding the insulator 16 may be, for example, PPS (polyphenylene sulfide), POM (polyoxymethylene), or PA66 (nylon 66).

[0024] The multiple coils 17 configure, for example, a three-phase coil. Terminals 21 (see also FIG. 1) are connected to the three-phase coil. By winding the multiple coils 17 around the teeth 14a of the stator core 14 via the insulators 16, an appropriate pressing force acts on the multiple electromagnetic steel sheets 15 toward the center in the axis O direction (stacking direction). For this reason, gaps between the multiple electromagnetic steel sheets 15 become so small that they are almost nonexistent.

[0025] FIG. 5 is a perspective view showing a state in which the stator core in FIG. 4 is formed into a primary molded product. 2 and 5, motor cover 18 is formed so as to cover multiple coils 17, for example, by molding stator core 14 with resin using a metal mold (hereinafter sometimes referred to as primary molding). In this way, multiple coils 17 are protected by motor cover 18. Hereinafter, a part formed by primarily molding motor cover 18 onto stator core 14 may be referred to as primary molded product Mo1. The motor cover 18 is formed from a resin such as PPS or POM.

[0026] The motor cover 18 is formed, for example, to support a plurality of electromagnetic steel sheets 15 in a stacked state in the direction of the axis O. By supporting the plurality of electromagnetic steel sheets 15 in a stacked state in the direction of the axis O by the motor cover 18, the gaps between the plurality of electromagnetic steel sheets 15 in the direction of the axis O are ensured to be smaller. One end 18a of the motor cover 18 protrudes in the direction of the axis O from the stator core 14 toward the outlet cover 4. An outer peripheral surface 18b at the one end 18a of the motor cover 18 is formed to have a radial dimension slightly larger than an outer peripheral surface 14c of the stator core 14. The other end 18c of the motor cover 18 protrudes in the direction of the axis O from the stator core 14 toward the pump section P.

[0027] The rotor 12 includes a rotor core 25 and an output shaft 26 to which the rotor core 25 is fixed. The rotor core 25 is magnetized, for example, with N poles and S poles alternately arranged in the circumferential direction about the axis O. The output shaft 26 is fixed in a state in which it penetrates the rotor core 25 along the axis O, and rotates integrally with the rotor core 25. One end 26a of the output shaft 26 is rotatably supported, for example, by the outlet cover 4 via a bearing (not shown). The other end 26b of the output shaft 26 is rotatably supported by a pump case 41 (described later) via a bearing 28. The other end 26b of the output shaft 26 is connected to an impeller 40 (described later) of the pump section P.

[0028] Here, a fuel flow path 30 is formed by a gap between the outer peripheral surface 25a of the rotor core 25 and the inner peripheral surface 14d of the stator core 14. The fuel flow path 30 is a flow path through which the fuel pumped up by the pump section P passes.

[0029] <Outlet cover> FIG. 6 is a perspective view showing a state in which the primary molded product in FIG. 5 has been formed into a secondary molded product. 2 and 6, the outlet cover 4 is formed by molding the motor cover 18 on the stator core 14 in the primary molding, and then, for example, molding the motor cover 18 of the primary molded product Mo1 with resin using a metal mold (hereinafter, sometimes referred to as secondary molding). The resin for molding the outlet cover 4 is, for example, PPS or POM.

[0030] The outer periphery 4a of the outlet cover 4 is formed to have a radial dimension larger than the outer periphery surface 14c of the stator core 14. The outer periphery 4a of the outlet cover 4 is formed, for example, to have the same radial dimension as the outer periphery surface 18b of one end 18a of the motor cover 18. A discharge port 4b is formed in the outlet cover 4 on the opposite side of the pump motor M in the direction of the axis O. The discharge port 4b is a portion where the fuel pumped up by the pump section P of the fuel pump 1 is guided through a flow path 30 of the pump motor M. A check valve (not shown) is provided in the discharge port 4b to prevent backflow of the fuel. A cover step 4c for crimping the housing case 6 is formed on the outer periphery of the outlet cover 4.

[0031] Hereinafter, the part in which the outlet cover 4 is molded onto the motor cover 18 of the primary molded product Mo1 may be referred to as the secondary molded product Mo2. That is, the secondary molded product Mo2 includes the stator core 14, the insulator 16, the coils 17, the motor cover 18, and the outlet cover 4. In the secondary molded product Mo2, a tin plating film C is formed by electrolytic plating on an exposed portion E of the secondary molded product Mo2 that is exposed to the outside of the stator core 14. The exposed portion E is the outer peripheral surface 14c and the inner peripheral surface 14d of the stator core 14.

[0032] <Pump section> 2, for example, a non-positive displacement pump having an impeller 40 is used as the pump section P. The pump section P pumps up fuel from inside a fuel tank (not shown). The pump section P includes the impeller 40 and a pump case 41 that covers the entire impeller 40. The impeller 40 is made of resin and formed into a disk shape. The impeller 40 is connected to the other end 26b of the output shaft 26 of the pump motor M so as to be non-rotatable relative to the other end 26b. The impeller 40 has a plurality of blades (not shown) formed along the outer periphery 40a in the circumferential direction centered on the axis O. The impeller 40 is rotatably housed inside the pump case 41.

[0033] The pump case 41 includes a first case portion 42 and a second case portion 43 which overlap in the direction of the axis O. The first case portion 42 is provided at an end portion of the pump motor M opposite the outlet cover 4 (i.e., the other end portion 18c of the motor cover 18). The second case portion 43 is provided at an end portion of the first case portion 42 opposite the pump motor M. A suction pipe 43a is formed in the second case portion 43 on the opposite side of the second case portion 43 in the direction of the axis O. The suction pipe 43a is a portion where fuel is pumped up into the inside of the pump portion P (i.e., the fuel flow path 30).

[0034] <Housing case> As shown in Figures 1 and 2, the housing case 6 has, for example, a cylindrically formed case body (an example of the tubular portion in the claims) 50, a crimping portion 51 formed at the end on the outlet cover 4 side, and a flange 52 formed at the end on the second case portion 43 side.

[0035] The case body 50 is formed in a cylindrical shape so as to cover the pump motor M, the outlet cover 4, and the pump section P. One end 50a of the case body 50 is fitted in a state of contact with the outer circumferential surface 18b of one end 18a of the motor cover 18 and the outer periphery 4a of the outlet cover 4. The other end 50b of the case body 50 is fitted in a state of contact with the outer periphery 41a of the pump case 41.

[0036] An outer circumferential surface 18b of one end 18a of the motor cover 18 and an outer circumferential surface 4a of the outlet cover 4 are formed to have a larger radial dimension than an outer circumferential surface 14c of the stator core 14. Therefore, a space S is formed between the outer circumferential surface 14c of the stator core 14 and the case body 50.

[0037] The flange 52 is bent radially inward from the other end 50b of the case body 50 into an annular shape. The flange 52 is engaged with a case step 43b formed at an end of the second case part 43. The crimped part 51 is crimped radially inward from one end 50a of the case body 50, and is thereby engaged with a cover step 4c of the outlet cover 4.

[0038] Before the crimping portion 51 is crimped, the housing case 6 is fitted from the second case portion 43 side to the cover step portion 4c of the outlet cover 4. By fitting the crimping portion 51 up to the cover step portion 4c, the flange 52 is engaged with the case step portion 43b. In this state, the crimping portion 51 is crimped radially inward to be engaged with the cover step portion 4c. Therefore, the housing case 6 is fixed in a fitted state with the pump motor M, the outlet cover 4, and the pump portion P. As a result, the outlet cover 4 and the pump portion P are integrated with the pump motor M.

[0039] <Fuel pump manufacturing method> Next, a method for manufacturing the fuel pump 1 will be described with reference to FIGS. As shown in FIG. 3, first, a plurality of electromagnetic steel sheets 15 are laminated in the direction of the axis O to form the stator core 14 (lamination process).

[0040] Next, as shown in Fig. 4, the teeth 14a of the formed stator core 14 are covered with insulators 16. Then, a plurality of coils 17 (see Fig. 2) are wound around the insulators 16, thereby winding the plurality of coils 17 around the teeth 14a (see Fig. 3) of the stator core 14 via the insulators 16 (winding process). A three-phase coil is formed from the wound coils 17, and terminals 21 are connected to the three-phase coil. After the winding process, an appropriate pressing force acts on the plurality of electromagnetic steel sheets 15 toward the center in the direction of the axis O, so that gaps between the plurality of electromagnetic steel sheets 15 become small enough to be almost nonexistent.

[0041] Next, as shown in Figures 5 and 6, with multiple coils 17 (see Figure 2) wound around the stator core 14, the motor cover 18 is primarily molded with resin on the stator core 14. The motor cover 18 is primarily molded on the stator core 14 to form a primary molded product Mo1. The multiple coils 17 are then covered with the motor cover 18. Furthermore, the outlet cover 4 is secondarily molded with resin on the primary molded product Mo1 to form a secondary molded product Mo2 (molding process).

[0042] When the primary molded product Mo1 and the secondary molded product Mo2 are molded, appropriate pressure is applied to the stator core 14 by a die or the like (not shown). Therefore, the multiple electromagnetic steel sheets 15 are in close contact with each other, and gaps between the multiple electromagnetic steel sheets 15 are maintained to an extent that they are almost nonexistent.

[0043] Next, the secondary molded product Mo2 is washed in a washing step, and in a step after the washing, the stator core 14 of the secondary molded product Mo2 is subjected to electrolytic plating to form a tin plating film C (plating step). Specifically, an electrode (not shown) is brought into contact with the outer peripheral surface 14c of the stator core 14, and electrolytic plating is applied to the stator core 14. As a result, a tin plating film C is formed on the exposed portion E of the stator core 14 (the outer peripheral surface 14c and the inner peripheral surface 14d).

[0044] At this time, the tin plating film C is not formed on the portion of the outer circumferential surface 14c of the stator core 14 where the electrode (not shown) is in contact, and an electrode contact mark T (see FIG. 6) remains (is formed) due to the contact of the electrode. This completes the manufacture of the stator 10. In this manner, the stator 10 is formed by carrying out the lamination process, winding process, molding process, and plating process in the manufacturing method of the fuel pump 1.

[0045] <Fuel pump operation> Next, the operation of the fuel pump 1 will be described with reference to FIG. 2, when the pump motor M of the fuel pump 1 is driven, the pump section P is driven thereby. Specifically, when the pump motor M is driven, the output shaft 26 rotates, which in turn rotates the impeller 40 that is connected to the output shaft 26 so as not to rotate relative to it. As the impeller 40 rotates, fuel in the fuel tank is pumped up into the pump section P from the suction pipe 43a.

[0046] The fuel pumped up into the pump section P is pressurized inside the pump section P, and the pressurized fuel is discharged into the pump motor M through a fuel flow path hole (not shown). The fuel discharged into the pump motor M is discharged into the discharge port 4b of the outlet cover 4 through a fuel flow path 30 inside the pump motor M. The fuel flow path 30 is formed by a gap between the outer peripheral surface 25a of the rotor core 25 and the inner peripheral surface 14d of the stator core 14. The fuel guided from the fuel flow path 30 to the discharge port 4b is guided to the internal combustion engine 2 (see FIG. 1).

[0047] <Effects of the embodiment> In this way, in the fuel pump 1 of the embodiment, as shown in Figs. 4 to 6, a secondary molded product Mo2 is formed by providing the stator core 14 with the insulator 16, the multiple coils 17 (see Fig. 2), the motor cover 18, and the outlet cover 4. In the secondary molded product Mo2 thus formed, an electrode (not shown) is brought into contact with the outer peripheral surface 14c of the stator core 14, and electrolytic plating is performed. As a result, a tin plating film C is formed on the outer peripheral surface 14c and the inner peripheral surface 14d of the stator core 14. For this reason, for example, it is difficult to suitably form the tin plating film C at the portion of the outer peripheral surface 14c of the stator core 14 where the electrode is brought into contact. This becomes the electrode contact mark T, and it is considered that rust will occur on the electrode contact mark T.

[0048] 2, a fuel flow path 30 in the pump motor M is formed in the gap between the outer peripheral surface 25a of the rotor core 25 and the inner peripheral surface 14d of the stator core 14. This makes it possible to prevent the fuel supplied to the internal combustion engine 2 (see FIG. 1) from flowing onto the outer peripheral surface 14c of the stator core 14. This makes it possible to prevent rust generated at the electrode abutment mark T on the outer peripheral surface 14c of the stator core 14 from being mixed into the fuel supplied to the internal combustion engine 2.

[0049] Furthermore, the housing case 6 is formed to be larger in radial dimension than the outer peripheral surface 14c of the stator core 14. A tin-plated coating C is formed on the outer peripheral surface 14c of the stator core 14. Therefore, for example, when the stator 10 is housed in the housing case 6, the inner periphery of the housing case 6 can be prevented from contacting the tin-plated coating C of the stator core 14. This makes it possible to prevent the inner periphery of the housing case 6 from contacting the tin-plated coating C and peeling off from the outer peripheral surface 14c of the stator core 14.

[0050] Furthermore, by forming the housing case 6 to be larger in radial dimension than the outer circumferential surface 14c of the stator core 14, a space S is formed between the outer circumferential surface 14c of the stator core 14 and the case body 50 of the housing case 6. Therefore, rust that has developed at the electrode abutment marks T on the outer circumferential surface 14c of the stator core 14 can escape to the space S. This makes it possible to prevent the rust that has developed at the electrode abutment marks T from entering the gaps between the electromagnetic steel sheets 15.

[0051] 2 and 6, according to the manufacturing method of the fuel pump 1 in the embodiment, a plating process is performed after the lamination process, the winding process, and the molding process. In this plating process, a tin plating film C is formed on the outer peripheral surface 14c and the inner peripheral surface 14d of the stator core 14. Specifically, in the plating process, an electrode (not shown) is brought into contact with the outer peripheral surface 14c of the stator core 14, and electrolytic plating is performed to form the tin plating film C on the outer peripheral surface 14c and the inner peripheral surface 14d of the stator core 14.

[0052] Incidentally, when forming the tin plating film C on the outer peripheral surface 14c and the inner peripheral surface 14d of the stator core 14, for example, it is also possible to perform plating treatment on the stator core 14 alone. However, in this case, gaps may occur between the stacked electromagnetic steel sheets 15, and plating liquid may remain between the multiple electromagnetic steel sheets 15. For this reason, unevenness or rust of the tin plating film C may occur on the outer peripheral surface 14c and the inner peripheral surface 14d of the stator core 14. In addition, the plating film may be formed between the electromagnetic steel sheets 15, causing iron loss and causing a decrease in motor performance. In order to prevent the occurrence of plating unevenness, rust, and the like, and further the decrease in motor performance due to iron loss, it is important to manage the type and conditions of the plating film, and from this perspective, there is room for improvement.

[0053] Furthermore, when forming a tin plating film C on the outer peripheral surface 14c and the inner peripheral surface 14d of the stator core 14 alone, a plurality of coils 17 (see FIG. 2) are wound around the stator core 14 on which the tin plating film C has been formed. Furthermore, after winding the plurality of coils 17, the motor cover 18 and the outlet cover 4 are molded around the stator core 14 using a metal mold. Here, the dimensional accuracy of the molded products is strictly set for the metal molds used to mold the motor cover 18 and the outlet cover 4 onto the stator core 14. Therefore, if the tin plating film C is not stably formed on the outer peripheral surface 14c and the inner peripheral surface 14d of the stator core 14, the setting of the stator core 14 in the metal mold may deteriorate, or the tin plating film C may peel off from the stator core 14.

[0054] Therefore, in the secondary molded product Mo2 in which the motor cover 18 and the outlet cover 4 are molded on the stator core 14, electrolytic plating is applied to the stator core 14 to form a tin plating film C on the outer peripheral surface 14c and the inner peripheral surface 14d of the stator core 14. Prior to the formation of the secondary molded product Mo2, a plurality of coils 17 (see FIG. 2) are wound around the teeth 14a of the stator core 14 via the insulators 16. This ensures that the gaps between the plurality of electromagnetic steel sheets 15 in the direction of the axis O are small. In this state, the primary molded product Mo1 supports the plurality of electromagnetic steel sheets 15 in a stacked state in the direction of the axis O by the motor cover 18. This ensures that the gaps between the plurality of electromagnetic steel sheets 15 in the direction of the axis O are even smaller.

[0055] Therefore, in the secondary molded product Mo2, the multiple electromagnetic steel sheets 15 of the stator core 14 are in close contact with each other. Therefore, there is almost no gap between the multiple electromagnetic steel sheets 15. As a result, it is possible to prevent the plating liquid from penetrating into the gaps between the multiple electromagnetic steel sheets 15, and the tin plating film C can be formed only on the outer peripheral surface 14c and the inner peripheral surface 14d of the stator core 14 where the plating film is required. The plating liquid does not remain between the multiple electromagnetic steel sheets 15, and unevenness in the tin plating film C can be prevented. In addition, it is possible to form a stable tin plating film C on the outer peripheral surface 14c and the inner peripheral surface 14d of the stator core 14. It is possible to prevent the formation of a plating film between the electromagnetic steel sheets 15, which causes iron loss and reduces motor performance. In addition, it is possible to easily manage the type and conditions of electrolytic plating, and the production process can be simplified. Furthermore, it is possible to prevent the deterioration of the settability in the mold and the peeling of the tin plating film C.

[0056] Furthermore, the insulator 16, the motor cover 18, and the outlet cover 4 are formed using, for example, PPS, POM, or PA66 as the resin. PPS, POM, and PA66 have chemical resistance to the cleaning process required for pretreatment of electrolytic plating of the stator core 14. Therefore, by forming the tin plating film C on the outer peripheral surface 14c and the inner peripheral surface 14d of the stator core 14 in the secondary molded product Mo2, it is possible to prevent the quality of the insulator 16, the motor cover 18, and the outlet cover 4 from being adversely affected.

[0057] In addition, the multiple coils 17 (see FIG. 2) are overmolded with the insulator 16, motor cover 18, etc. Therefore, in a cleaning process required as a pretreatment for electrolytic plating of the stator core 14, the multiple coils 17 can be protected from the cleaning solution used for cleaning by the insulator 16, motor cover 18, etc. This makes it possible to prevent the quality of the multiple coils 17 from being adversely affected by electrolytic plating of the secondary molded product Mo2 to form a tin plating film C on the outer peripheral surface 14c and inner peripheral surface 14d of the stator core 14.

[0058] The present invention is not limited to the above-described embodiment, and includes various modifications to the above-described embodiment without departing from the spirit of the present invention.

[0059] For example, in the above embodiment, the fuel pump 1 has been described as an example of a liquid pump. The fuel pump 1 has been described as an in-tank type that is immersed in fuel inside a fuel tank of a vehicle such as an automobile or motorcycle. However, the present invention is not limited to this, and the above configuration can be adopted for fuel pumps that supply fuel to various devices. Furthermore, the above configuration can be adopted for various liquid pumps that pump up various liquids, not limited to fuel.

[0060] In the above embodiment, the case has been described where electrolytic plating is applied to the exposed portion E (the outer peripheral surface 14c, the inner peripheral surface 14d) of the stator core 14 to form the tin plating film C. However, this is not limited thereto, and various plating films formed by electrolytic plating instead of the tin plating film C may be formed on the exposed portion E of the stator core 14.

[0061] In addition, within the scope of the invention, the components in the above-described embodiments may be replaced with well-known components, and the above-described modified examples may be combined as appropriate. [Explanation of symbols]

[0062] 1...fuel pump (liquid pump), 2...internal combustion engine, 4...outlet cover, 4a...outer periphery, 4b...discharge port, 4c...cover step portion, 6...housing case, 10...stator, 12...rotor, 14...stator core, 14a...teeth, 14b...slot, 14c...outer periphery (exposed portion), 14d...inner periphery (exposed portion), 15...electromagnetic steel sheet, 16...insulator, 17...coil, 18...motor cover, 18a...one end portion, 18b...outer periphery, 18c...other end portion, 21...terminal, 25...rotor core, 25a...outer Circumferential surface, 26...output shaft, 26a...one end, 26b...other end, 28...bearing, 30...flow path, 40...impeller, 40a...outer periphery, 41...pump case, 41a...outer periphery, 42...first case part, 43...second case part, 43a...suction pipe, 43b...case step, 50...case main body (one example of the cylindrical part in the claims), 50...case main body, 50a...one end, 50b...other end, 51...crimped part, 52...flange, C...tin plating coating, E...exposed part, Mo1...primary molded part, Mo2...secondary molded part, O...axis, T...electrode contact mark

Claims

1. A pump unit that pumps up the liquid; A pump motor that drives the pump unit; Equipped with The pump motor is A stator; a rotor rotatably provided on the radially inner side of the stator and connected to the pump portion; a flow path formed between the stator and the rotor, through which the liquid pumped up by the pump portion flows; Equipped with The stator includes: a stator core formed by laminating a plurality of electromagnetic steel sheets; A plurality of coils wound around the stator core; a motor cover for protecting the coils; Equipped with a plating film is formed by electrolytic plating on an exposed portion of the stator core that is exposed to an outside in a state in which the plurality of coils and the motor cover are attached to the stator core, An electrode abutment mark is formed on the outer peripheral surface of the stator core of the exposed portion, the electrode abutting the exposed portion when the electrolytic plating is performed. A liquid pump characterized by:

2. A housing case having a cylindrical portion is provided, The pump unit is accommodated in the housing case, The outer circumferential surface of the stator is fitted to the inner circumferential surface of the cylindrical portion.

2. The liquid pump according to claim 1.

3. The housing case has a radial dimension larger than the outer circumferential surface of the stator core.

3. The liquid pump according to claim 2.

4. A pump unit that pumps up the liquid; A pump motor that drives the pump unit; Equipped with The pump motor is A stator; a rotor rotatably provided on the radially inner side of the stator and connected to the pump portion; a flow path formed between the stator and the rotor, through which the liquid pumped up by the pump portion flows; A method for manufacturing a liquid pump comprising: The stator includes: a lamination process for laminating a plurality of electromagnetic steel sheets to form a stator core; a winding step of winding a plurality of coils around the stator core; a molding step of molding a motor cover for protecting the plurality of coils; a plating step of contacting an electrode with an outer peripheral surface of the stator core and performing electrolytic plating to form a plating film on an exposed portion of the stator core, the exposed portion being exposed to the outside of the stator core after the forming step; Formed by A method for manufacturing a liquid pump comprising the steps of:

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