JP2025021814A - Liquid pump and method for manufacturing the liquid pump - Google Patents

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

The present invention relates to a liquid pump and a method for manufacturing a liquid pump.

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 placed inside the fuel tank and submerged in the fuel. The fuel pump has a pump motor and a pump section inside a cylindrical housing case. The fuel pump pressurizes the fuel in the fuel tank in the pump section by rotating the pump section 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.

In the above fuel pump, for example, a stator core is known that is provided with an insulator, a motor cover, etc., and then electrolytic plating is performed on the stator core to form a tin plating film (Sn plating film). By forming a tin plating film on the stator core, it is possible to ensure the corrosion resistance of the stator core (see, for example, Patent Document 1).

JP 2015-83828 A

When electrolytic plating is performed on a stator core, for example, an electrode is brought into contact with the outer peripheral surface of the stator core. In this case, it is difficult to form a plating film on the portion of the outer peripheral surface of the stator core where the electrode is brought into contact, and a mark is left. It is considered that rust will develop on this mark. For example, in a fuel pump, if 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 the internal combustion engine along the outer peripheral surface of the stator core. For this reason, there is a concern that rust that has developed on the outer peripheral surface of the stator core will be mixed into the fuel.

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

In order to solve the above problems, the first aspect of the present invention includes a pump section that pumps up a liquid and a pump motor that drives the pump section. The pump motor includes a stator, a rotor that is rotatably provided radially inside the stator and connected to the pump section, and a flow path formed between the stator and the rotor through which the liquid pumped up by the pump section flows. The stator includes a stator core in which multiple electromagnetic steel sheets are laminated, multiple coils wound around the stator core, and a motor cover that protects the multiple coils. When the multiple coils and the motor cover are attached to the stator core, a plating film is formed by applying electrolytic plating to the exposed portion of the stator core that is exposed to the outside, and an electrode contact mark is formed on the outer peripheral surface of the stator core of the exposed portion, which is caused by an electrode contacting the exposed portion when the electrolytic plating is applied.

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 a plating film will not form on the electrode marks, resulting in rust. Therefore, by configuring as described above, it is possible to prevent rust from being mixed into the fuel supplied to the internal combustion engine, even when the liquid pump is used as a fuel pump that supplies fuel to the internal combustion engine.

In a second aspect of the present invention, the liquid pump of the first aspect may include a housing case having a cylindrical portion, the pump portion being housed within the housing case, and the outer peripheral surface of the stator may be fitted to the inner peripheral surface of the cylindrical portion.

This configuration ensures that the space between the stator and rotor is a flow path through which liquid can flow.

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.

This configuration prevents the plating coating from coming into contact with the inner circumferential surface of the housing case and peeling off from the outer circumferential surface of the stator core.

In a fourth aspect of the present invention, a method for manufacturing a liquid pump includes a pump section that pumps up liquid, and a pump motor that drives the pump section, the pump motor including a stator, a rotor that is rotatably provided radially inside the stator and connected to the pump section, and a flow path formed between the stator and the rotor through which the liquid pumped up by the pump section flows. In this method, the stator is formed by a lamination process in which a stator core is formed by laminating a plurality of electromagnetic steel sheets, a winding process in which a plurality of coils are wound around the stator core, a molding process in which a motor cover that protects the plurality of coils is formed, and a plating process in which, after the molding process, an electrode is brought into contact with the outer peripheral surface of the stator core and electrolytic plating is performed to form a plating film on the exposed portion exposed to the outside of the stator core.

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.

The present invention can prevent rust from being mixed into the fuel supplied to an internal combustion engine, for example.

1 is a perspective side view of a fuel pump according to an embodiment of the present invention; 2 is a side view of the fuel pump of FIG. 1 with a housing case and a pump motor partially cut away. FIG. 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. 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 . 5 is a perspective view showing a state in which the stator core of FIG. 4 is formed into a primary molded product. FIG. 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.

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

<Fuel pump>
Fig. 1 is a perspective side view of a 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.

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 centered on the axis O may be simply referred to as the "radial direction", and the circumferential direction centered on the axis O may be simply referred to as the "circumferential direction".

<Pump motor>
Fig. 3 is a perspective view showing the 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 the 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.

The stator 10 includes a cylindrical stator core 14 formed from multiple stacked electromagnetic steel plates 15, an insulator 16 that covers the teeth 14a of the stator core 14, multiple coils 17 wound around the teeth 14a via the insulator 16, and a motor cover 18 that protects the multiple coils 17.

The stator core 14 is formed by stacking multiple annular electromagnetic steel sheets 15 in the direction of the axis O. The stator core 14 has multiple teeth 14a that protrude radially inward. The stator core 14 has slots 14b formed between adjacent teeth 14a in the circumferential direction.

The insulator 16 is molded, for example, from a resin so as to cover the teeth 14a of the stator core 14. The resin used to mold the insulator 16 is, for example, PPS (polyphenylene sulfide), POM (polyoxymethylene), or PA66 (nylon 66).

The multiple coils 17, for example, configure 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). As a result, the gaps between the multiple electromagnetic steel sheets 15 become so small that they are almost nonexistent.

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

The motor cover 18 is formed, for example, to support the multiple electromagnetic steel sheets 15 in a stacked state in the direction of the axis O. By supporting the multiple electromagnetic steel sheets 15 in a stacked state in the direction of the axis O by the motor cover 18, the gaps between the multiple 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.

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 centered on 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 the pump case 41 (described later) via a bearing 28. The other end 26b of the output shaft 26 is connected to the impeller 40 (described later) of the pump section P.

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

<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 used to mold the outlet cover 4 is, for example, PPS or POM.

The outer periphery 4a of the outlet cover 4 is formed to have a radial dimension larger than the outer periphery 14c of the stator core 14. The outer periphery 4a of the outlet cover 4 is formed to have the same radial dimension as the outer periphery 18b of one end 18a of the motor cover 18, for example.
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.

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, multiple 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 the 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.

<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 an outer periphery 40a in the circumferential direction centered on the axis O. The impeller 40 is rotatably housed inside a pump case 41.

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

<Housing case>
As shown in Figures 1 and 2, the housing case 6 has, for example, a cylindrically formed case body (an example of a 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.

The case body 50 is formed in a cylindrical shape 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 contact with the outer circumferential surface 18b of one end 18a of the motor cover 18 and the outer circumferential surface 4a of the outlet cover 4. The other end 50b of the case body 50 is fitted in contact with the outer circumferential surface 41a of the pump case 41.

The outer peripheral surface 18b of one end 18a of the motor cover 18 and the outer peripheral surface 4a of the outlet cover 4 are formed with a radial dimension larger than the outer peripheral surface 14c of the stator core 14. Therefore, a space S is formed between the outer peripheral surface 14c of the stator core 14 and the case body 50.

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

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 engages with the case step portion 43b. In this state, the crimping portion 51 is crimped radially inward to engage with the cover step portion 4c. This fixes the housing case 6 in a fitted state with the pump motor M, outlet cover 4, and pump portion P. As a result, the outlet cover 4 and pump portion P are integrated with the pump motor M.

<Manufacturing method of fuel pump>
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).

Next, as shown in FIG. 4, the teeth 14a of the formed stator core 14 are covered with an insulator 16. Then, by winding multiple coils 17 (see FIG. 2) around the insulator 16, the multiple coils 17 are wound around the teeth 14a (see FIG. 3) of the stator core 14 via the insulator 16 (winding process). A three-phase coil is formed with the multiple wound coils 17, and terminals 21 are connected to the three-phase coil. After the winding process, an appropriate pressing force acts on the multiple electromagnetic steel sheets 15 toward the center in the axis O direction, so that the gaps between the multiple electromagnetic steel sheets 15 are reduced to an almost nonexistent level.

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 by 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).

When the primary molded product Mo1 and the secondary molded product Mo2 are molded, appropriate pressure is applied to the stator core 14 using 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.

Next, the secondary molded product Mo2 is washed in a washing step, and in a step after the washing, a tin plating film C is formed by electrolytic plating on the stator core 14 of the secondary molded product Mo2 (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).

At this time, the tin plating film C is not formed on the outer peripheral surface 14c of the stator core 14 where the electrode (not shown) is in contact, and electrode contact marks T (see FIG. 6) remain (are formed) due to the contact of the electrode. This completes the manufacture of the stator 10. In this way, 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.

<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.

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 outlet 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 the 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 led from the fuel flow path 30 to the discharge port 4b is led to the internal combustion engine 2 (see FIG. 1).

Effects of the embodiment
In this way, in the fuel pump 1 of the embodiment, as shown in Figures 4 to 6, a secondary molded product Mo2 is formed, which includes the stator core 14, the insulator 16, the multiple coils 17 (see Figure 2), the motor cover 18, and the outlet cover 4. In the secondary molded product Mo2 thus formed, an electrode (not shown) is abutted against 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, it is difficult to suitably form the tin plating film C at the portion where the electrode is abutted on the outer peripheral surface 14c of the stator core 14. This becomes the electrode abutment mark T, and it is considered that rust will occur on the electrode abutment mark T.

As shown in FIG. 2, the 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 prevents 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 prevents rust that has developed at the electrode abutment marks 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.

The housing case 6 is also 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 stored in the housing case 6, the inner circumference of the housing case 6 can be prevented from contacting the tin-plated coating C of the stator core 14. This prevents the inner circumference 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.

Furthermore, by forming the housing case 6 to be larger in radial dimension than the outer peripheral surface 14c of the stator core 14, a space S is formed between the outer peripheral 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 peripheral surface 14c of the stator core 14 can escape into 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.

As shown in Figs. 2 and 6, in 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 abutted against 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.

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, it is possible to perform the plating process on the stator core 14 alone. However, in this case, gaps may occur between the stacked electromagnetic steel sheets 15, and the plating liquid may remain between the electromagnetic steel sheets 15. This may cause unevenness or rust in the tin plating film C 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 uneven plating and rust, as well as 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.

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. After the plurality of coils 17 are wound, the motor cover 18 and the outlet cover 4 are molded around the stator core 14 using a die.
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 to the metal mold may deteriorate, or the tin plating film C may peel off from the stator core 14.

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 forming the secondary molded product Mo2, multiple 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 multiple electromagnetic steel sheets 15 in the direction of the axis O are small. In this state, the multiple electromagnetic steel sheets 15 are supported by the motor cover 18 in a stacked state in the direction of the axis O by the primary molded product Mo1. This ensures that the gaps between the multiple electromagnetic steel sheets 15 in the direction of the axis O are even smaller.

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. There is no residual plating liquid between the multiple electromagnetic steel sheets 15, and unevenness in the tin plating film C can be prevented. In addition, a stable tin plating film C can be formed 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 deterioration of the settability in the mold and peeling of the tin plating film C.

Furthermore, the insulator 16, motor cover 18, and outlet cover 4 are formed using resin such as PPS, POM, or PA66. PPS, POM, and PA66 are chemically resistant to the cleaning process required for pretreatment of the stator core 14 before electrolytic plating. Therefore, by forming a tin plating film C on the outer peripheral surface 14c and 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, motor cover 18, and outlet cover 4 from being adversely affected.

In addition, the multiple coils 17 (see FIG. 2) are overmolded with the insulator 16, motor cover 18, etc. Therefore, in the cleaning process required for pretreatment of the stator core 14 with electrolytic plating, the multiple coils 17 can be protected from the cleaning solution used 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 and forming a tin plating film C on the outer peripheral surface 14c and inner peripheral surface 14d of the stator core 14.

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

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 submerged in fuel inside the fuel tank of a vehicle such as an automobile or motorcycle. However, the present invention is not limited to this, and the above-described configuration can be adopted for fuel pumps that supply fuel to various devices. Furthermore, the above-described configuration can be adopted for various liquid pumps that pump various liquids, not limited to fuel.

In the above embodiment, a case has been described in which electrolytic plating is applied to the exposed portion E (outer peripheral surface 14c, inner peripheral surface 14d) of the stator core 14 to form the tin plating film C. However, this is not limited to this, 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.

In addition, the components in the above embodiment may be replaced with well-known components as appropriate without departing from the spirit of the present invention, and the above-mentioned modifications may be combined as appropriate.

1...fuel pump (liquid pump), 2...internal combustion engine, 4...outlet cover, 4a...outer periphery, 4b...discharge port, 4c...cover step, 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 plate, 16...insulator, 17...coil, 18...motor cover, 18a...one end, 18b...outer periphery, 18c...other end, 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 product, Mo2...secondary molded product, O...axis, T...electrode contact mark

Claims (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;
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: 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. 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. 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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