JP6115411B2 - Fuel pump - Google Patents

Description

  The present invention relates to a fuel pump.

Conventionally, a fuel pump that supplies fuel in a fuel tank to an internal combustion engine is known.
The fuel pump described in Patent Document 1 has a vapor discharge hole for discharging vapor (bubbles) generated in fuel from a fuel flow path formed along a blade groove of an impeller that pressurizes the fuel by rotational driving. I have. In addition, the fuel pump includes an enlarged flow path portion in which the inner wall of the fuel flow path is expanded from the outer diameter side to the inner diameter side of the fuel flow path at the position where the vapor discharge hole is provided. The enlarged flow path portion temporarily collects vapor generated in the fuel flow path, and then discharges the vapor from the enlarged flow path portion through the vapor discharge hole to the outside of the fuel flow path.

JP-A-6-229390

However, in the fuel pump described in Patent Document 1, the inner wall of the enlarged flow path portion is provided perpendicular to the fuel flow direction of the fuel flow path from the outer diameter side to the inner diameter side of the fuel flow path. Further, the bottom wall of the enlarged flow path portion is provided perpendicular to the vapor discharge hole. As a result, the fuel flowing from the fuel flow path to the enlarged flow path portion flows through a location away from the inner wall of the enlarged flow path portion. For this reason, it is conceivable that a vortex is formed in the vicinity of the connection between the inner wall and the bottom wall of the enlarged flow path portion, and vapor is generated from the vortex due to a decrease in the fuel pressure of the vortex. When the vapor generated from the vortex flows into the vapor discharge hole, the vapor in the fuel flow path is less likely to flow into the vapor discharge hole. Therefore, the amount of vapor discharged from the fuel flow path to the vapor discharge hole may be reduced.
The present invention has been made in view of the above problems, and an object thereof is to provide a fuel pump capable of increasing the amount of vapor discharged from the vapor discharge hole.

The present invention provides a fuel pump having a vapor discharge hole for discharging the vapor from the fuel flow path, the vapor discharge hole is first passage communicating with the fuel flow path, the counter-fuel flow path side of the first flow path It has the 1st taper part provided in the connection location of the 2nd flow path which connects, and a 1st flow path and a 2nd flow path, It is characterized by the above-mentioned. The inner diameter of the first channel is larger than the inner diameter of the second channel. In the present invention, when the distance from the connection position between the fuel flow path and the first flow path to the connection position between the first flow path and the second flow path is L, and the inner diameter of the first flow path is d 2 ≦ d / L ≦ 5.
Thereby, the fuel flowing through the fuel flow path, without peeling from the inner wall of the vapor discharge hole, quickly flows from the first flow path along a first tapered portion to the second passage. Therefore, the fuel containing vapor can flow from the fuel flow path to the entire flow path of the vapor discharge hole without forming a swirl of fuel inside the inner wall of the first flow path. Accordingly, the vapor in the fuel flow path is surely discharged from the vapor discharge hole, and the vapor lock of the fuel pump can be prevented.

1 is a configuration diagram of a fuel supply system in which a fuel pump according to a first embodiment of the present invention is used. It is sectional drawing of the fuel pump by 1st Embodiment. It is a figure which shows only a lower casing by the III-III line of FIG. It is principal part sectional drawing of the IV-IV line of FIG. It is an enlarged view of the V part of FIG. It is a characteristic view of the shape of the 1st flow path of a vapor | steam discharge hole, and a vapor | steam discharge | emission amount ratio. It is an analysis figure which shows the fuel flow of the vapor | steam discharge hole of 1st Embodiment. It is an analysis figure which shows the fuel flow of the vapor | steam discharge hole of a comparative example. It is a principal part enlarged view of the vapor | steam discharge hole of the fuel pump by 2nd Embodiment. It is a principal part enlarged view of the vapor | steam discharge hole of the fuel pump by 3rd Embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
A first embodiment of the present invention is shown in FIGS. The fuel pump 1 according to this embodiment is used in a fuel supply system using a variable fuel pressure system, and pumps fuel in a fuel tank 2 to an internal combustion engine 4 through a fuel pipe 3.
As shown in FIG. 1, in this control system, an electronic control unit (ECU) 5 of the vehicle detects the number of revolutions of the impeller corresponding to the fuel pressure and flow rate required by the internal combustion engine 4, and the command value is detected by the fuel pump 1. To the controller (FPC) 6. The FPC 6 supplies a three-phase alternating current corresponding to the command value to the motor of the fuel pump 1.
The pressure of the fuel discharged from the fuel pump 1 to the fuel pipe 3 is detected by the pressure sensor 7, and the signal is transmitted to the ECU 5. The ECU 5 performs feedback control of the fuel pump 1 via the FPC 6 so that the fuel pressure detected by the pressure sensor 7 matches the target fuel pressure.

First, the overall configuration of the fuel pump 1 will be described.
As shown in FIG. 2, the fuel pump 1 includes a pump unit 10, a motor unit 30, a housing 39, a motor cover 40, and the like. The fuel pump 1 sucks fuel from the suction port 12 shown in the lower part of FIG. 2 by the rotation of the impeller 11 provided in the pump unit 10, boosts the fuel, and discharges it from the fuel discharge pipe 41 shown in the upper part of FIG. To do.

The pump unit 10 includes an impeller 11, an upper casing 13, a lower casing 14, and the like. The upper casing 13 and the lower casing 14 correspond to a “casing” described in the claims.
The impeller 11 is formed in a disk shape and has a plurality of blade grooves 15 arranged in the circumferential direction. The impeller 11 is fixed to the shaft 31 of the motor unit 30 and rotates together with the shaft 31.
A pump chamber 16 that houses the impeller 11 is formed between the upper casing 13 and the lower casing 14.
The lower casing 14 has an inlet 12 for introducing fuel into the pump chamber 16 from the outside of the fuel pump 1.
The upper casing 13 has a discharge port 17 that discharges fuel from the pump chamber 16 to the motor unit 30.

As shown in FIG. 3, the lower casing 14 has a fuel flow path 18 formed in an annular shape corresponding to the blade groove 15 of the impeller 11 from the suction port 12 to the discharge port 17. The fuel flow path 18 is formed in a substantially C shape. Further, the lower casing 14 has a vapor discharge hole 20 through which the vapor contained therein can be discharged together with fuel from the pump chamber 16 and the fuel flow path 18 to the outside of the fuel pump 1. The vapor discharge hole 20 will be described later.
As shown in FIG. 2, similarly to the lower casing 14, the upper casing 13 has a fuel flow path 19 formed in an annular shape corresponding to the blade groove 15 of the impeller 11 from the inlet 12 to the outlet 17. . The fuel flow paths 18 and 19 of the upper casing 13 and the lower casing 14 communicate with the pump chamber 16.
When the impeller 11 rotates together with the motor shaft 31, fuel is sucked into the pump chamber 16 and the fuel flow paths 18 and 19 from the suction port 12. The fuel flows as a spiral swirl between the blade groove 15 and the fuel flow paths 18 and 19 due to the rotation of the impeller 11, and is pressurized as it goes from the suction port 12 to the discharge port 17. Discharge from.

The motor unit 30 is a brushless motor and includes a stator 32, a rotor 36, a shaft 31, and the like.
The stator 32 has a cylindrical shape and includes a stator core 33, an insulator 34, and a winding 35. The stator core 33 is made of a magnetic material such as iron. The insulator 34 resin-molds the stator core 33. Winding 35 is wound around insulator 34 to form a three-phase winding. The insulator 34 around which the winding 35 is wound is further integrally molded by the motor cover 40 with resin. Therefore, the stator 32 is formed integrally with the motor cover 40.

The rotor 36 is rotatably accommodated inside the stator 32. In the rotor 36, a magnet 38 is fixed around the iron core 37. The magnet 38 has N and S poles alternately arranged in the circumferential direction.
The shaft 31 is press-fitted and fixed at the center of the rotor 36 and rotates together with the rotor 36. One end of the shaft 31 is rotatably supported by a bearing 42 provided on the motor cover 40, and the other end is rotatably supported by a bearing 43 provided on the upper casing 13.
When three-phase power is supplied from the U-phase, V-phase, and W-phase terminals 44 provided on the motor cover 40 to the windings 35 of each phase of the stator 32, a rotating magnetic field is generated in the stator 32, and the rotor 36 and The shaft 31 rotates.

The housing 39 is formed in a cylindrical shape, and one end portion in the axial direction is caulked in the radially inward direction to fix the motor cover 40 and the motor portion 30. In addition, the other end of the housing 39 is caulked radially inward to fix the lower casing 14 and the upper casing 13.
The motor cover 40 has a fuel discharge pipe 41 protruding upward in FIG. The fuel boosted by the pump unit 10 passes through the gap between the stator 32 and the rotor 36 of the motor unit 30 and is discharged from the fuel discharge pipe 41.

Next, the vapor discharge hole 20 provided in the fuel flow path 18 of the lower casing 14 will be described.
As shown in FIG. 3, the vapor discharge hole 20 has an angle θa in the range of about 110 ° to 130 ° when the position of the suction port 12 is 0 °. Vapor may be generated in the fuel sucked into the pump chamber 16 from the suction port 12 due to the suction negative pressure. The vapor discharge hole 20 discharges vapor generated in the vicinity of the suction port 12 to the outside of the fuel pump 1.
The fuel introduced into the fuel flow path 18 and the pump chamber 16 by the negative pressure from the suction port 12 is gradually increased in pressure and reaches several tens of kPa in the vicinity of the vapor discharge hole 20. Therefore, the fuel in the fuel flow path 18 is discharged from the vapor discharge hole 20 to the outside of the fuel pump 1.

As shown in FIG. 4, the fuel flow path 18 has an outer curved surface portion 181, a flat surface portion 182, and an inner curved surface portion 183 from the radially outer side toward the radially inner side. The outer curved surface portion 181 is a portion that gradually becomes deeper from the radially outer side toward the radially inner side. The flat portion 182 is a portion having a constant depth. The inner curved surface portion 183 is a portion that gradually becomes shallower from the flat surface portion 182 toward the inside of the diameter. The vapor discharge hole 20 is connected to the inner curved surface portion 183 of the fuel flow path 18.
Since the centrifugal force due to the rotation of the impeller 11 acts on the fuel flowing through the fuel flow path 18, the pressure of the fuel flowing radially outside the fuel flow path 18 is high. Since the vapor contained in the fuel has a smaller mass than the fuel, the vapor flows inside the fuel flow path 18 in the radial direction. Therefore, by connecting the vapor discharge hole 20 to the inner curved surface portion 183 of the fuel flow path 18, it is possible to reliably introduce the vapor flowing through the fuel flow path 18 into the vapor discharge hole 20.

The vapor discharge hole 20 includes a first flow path 21, a second flow path 22, a third flow path 23, and a first tapered portion 24. These are all formed coaxially.
The first flow path 21 is connected to the inner curved surface portion 183 of the fuel flow path 18 and communicates with the fuel flow path 18. The first flow path 21 prevents the fuel from peeling from the inner wall of the vapor discharge hole 20 when the fuel flows from the fuel flow path 18 into the vapor discharge hole 20.
The second flow path 22 has a smaller inner diameter than the first flow path 21, and communicates with the anti-fuel flow path side of the first flow path 21. The flow rate of the fuel flowing through the vapor discharge hole 20 is adjusted by setting the inner diameter and length of the second flow path 22.
The first taper portion 24 is provided at a connection portion between the first flow path 21 and the second flow path 22, and prevents the vortex from occurring in the fuel flowing through the step between the first flow path 21 and the second flow path 22. . The first taper portion 24 is provided in an annular shape on the outer side of the step provided between the first flow path 21 and the second flow path 22.
As shown in FIG. 5, the first taper portion 24 is formed so that the internal angle θb is 120 ° or less. This is because if the inner angle is larger than 120 °, a vortex is likely to occur in the fuel flowing there.

  As shown in FIG. 4, the third flow path 23 has a larger inner diameter than the second flow path 22 and communicates with the second flow path 22 on the side opposite to the first flow path. The third flow path 23 adjusts the length of the second flow path 22. The inner wall of the third flow path 23 is substantially parallel to the inner wall of the second flow path 22. However, the inner diameter d1 on the second flow path side of the third flow path 23 is slightly smaller than the inner diameter d2 on the anti-second flow path side. That is, when the lower casing 14 is formed, the inner wall of the third flow path 23 has a taper that is about the draft for extracting the mold that forms the third flow path 23 from the material constituting the lower casing 14. Thereby, the workability of the third flow path 23 can be improved. Further, when the vapor discharge hole 20 is formed, it is possible to easily remove burrs generated at the connection portion between the second flow path 22 and the third flow path 23.

As shown in FIG. 5, the distance from the connection position between the fuel flow path 18 and the first flow path 21 to the connection position between the first flow path 21 and the second flow path 22 (hereinafter referred to as “the length of the first flow path 21”). L), and the inner diameter of the first flow path 21 is d. At this time, the relationship between the length L of the first flow path 21 and its inner diameter d is preferably 2 ≦ d / L ≦ 5.
FIG. 6 shows the relationship between the d / L and the vapor discharge ratio when the impeller rotational speed is set to 3000 to 10000 rpm, which is typical for the fuel pump 1.
At this time, the vapor discharge ratio is 96.5% or more in the range of 1 ≦ d / L ≦ 6. Further, the vapor discharge ratio is 99% or more in the range of 2 ≦ d / L ≦ 5. In this way, by adjusting the relationship between the length L of the first flow path 21 and its inner diameter d, the shape of the vapor discharge hole 20 can be adjusted to the angle of the fuel flowing from the first flow path 21 to the second flow path 22. It is possible to match. Thereby, the vapor | steam discharged | emitted with a fuel from the fuel flow path 18 to the vapor | steam discharge hole 20 can be increased.

Next, the fuel flow in the vapor discharge hole 200 of the comparative example and the fuel flow in the vapor discharge hole 20 of the first embodiment will be compared and described.
As shown in FIG. 8, in the vapor discharge hole 200 of the comparative example, the second flow path 220 is directly connected to the fuel flow path 18 and does not have the first flow path 21 and the first taper portion 24. Further, the taper angle of the third flow path 230 of the comparative example is formed larger than the taper angle of the third flow path 23 of the first embodiment. In this case, the fuel flowing into the vapor discharge hole from the fuel flow path 18 is peeled off from the inner wall on the upstream side of the vapor discharge hole 200 as indicated by an arrow A and flows. Therefore, in the vicinity of the inner wall on the upstream side of the vapor discharge hole 200 where the separation has occurred, as shown by the broken line B, a vortex is generated and the fuel pressure is reduced. Therefore, when vapor is generated from the vortex, the amount of vapor discharged from the fuel flow path 18 is reduced by the volume of the vapor.
Further, in the vapor discharge hole 200 of the comparative example, as shown by the arrow C, the fuel flows only in a part of the third flow path 230. In the other part of the third flow path 230, as indicated by an arrow D, a flow for drawing fuel from the outside of the third flow path 230 is generated. As a result, the vapor discharge hole 200 of the comparative example has a small amount of vapor discharged from the fuel flow path 18.

On the other hand, as shown by arrow E in FIG. 7, in the first embodiment, the fuel flowing from the fuel flow path 18 to the vapor discharge hole 20 flows through the first flow path 21, the first tapered portion 24, and the second flow. It flows along the inner wall without peeling from the inner wall on the upstream side of the path 22. Therefore, no vortex flow is generated in the vicinity of the inner wall on the upstream side of the vapor discharge hole 20, and the amount of vapor discharged from the fuel flow path 18 is increased as compared with the vapor discharge hole 200 of the comparative example.
Further, as shown by the arrow F, the third flow path 23 of the vapor discharge hole 20 of the first embodiment allows the fuel flow from the second flow path 22 to flow without drawing fuel from the outside of the third flow path 23. It is possible to discharge the fuel pump 1 to the outside. Therefore, the vapor discharge hole 20 of the first embodiment can increase the amount of vapor discharged from the fuel flow path 18 compared to the vapor discharge hole 200 of the comparative example.

(Operational effect of this embodiment)
The fuel pump 1 of this embodiment has the following effects.
(1) In the present embodiment, the vapor discharge hole 20 has the first flow path 21 having an inner diameter larger than that of the second flow path 22 on the fuel flow path side of the second flow path 22. Furthermore, a first taper portion 24 is provided at a connection location between the first flow path 21 and the second flow path 22.
As a result, the fuel flowing through the fuel flow path 18 does not peel off from the inner rim on the upstream side of the vapor discharge hole 20, but along the inner walls of the first flow path 21, the first tapered portion 24, and the second flow path 22. It flows quickly. Therefore, it is possible to flow the fuel through all the flow paths of the vapor discharge hole 20 without forming a swirl of fuel inside the inner wall of the first flow path 21. Therefore, the vapor in the fuel flow path 18 is reliably discharged from the vapor discharge hole 20, so that the vapor lock of the fuel pump 1 can be prevented.

(2) In this embodiment, the 1st flow path 21, the 2nd flow path 22, and the 1st taper part 24 are provided coaxially.
As a result, the fuel flowing through the fuel flow path 18 quickly flows from the first flow path 21 to the first tapered portion 24 and the second flow path 22.

(3) In the present embodiment, the relationship between the length L of the first flow path 21 and the inner diameter d of the first flow path 21 is 2 ≦ d / L ≦ 5.
As a result, when the impeller rotational speed is set to, for example, 3000 to 10,000 rpm, the shape of the first flow path 21 can be adjusted to the angle of the fuel flowing from the fuel flow path 18 to the second flow path 22 through the first flow path 21. It is. Therefore, in the range of 2 ≦ d / L ≦ 5, the fuel that flows from the fuel flow path 18 to the vapor discharge hole 20 can be maximized.

(4) In the present embodiment, the vapor discharge hole 20 has a third flow path 23 having a larger inner diameter than the second flow path 22 on the side opposite to the first flow path of the second flow path 22.
Accordingly, it is possible to discharge an appropriate flow rate from the fuel flow path 18 without making the second flow path 22 serving as the fuel throttle portion longer than necessary.

(5) In this embodiment, when forming the lower casing 14, the inner wall of the third flow path 23 has a draft angle for pulling out the mold forming the third flow path 23 from the material constituting the lower casing 14. It has a taper.
Thereby, the workability of the 3rd flow path 23 can be improved. Further, when the vapor discharge hole 20 is formed, it is possible to easily remove burrs generated at the connection portion between the second flow path 22 and the third flow path 23.
Further, by reducing the taper angle of the third flow path 23, it is possible to prevent the fuel from being drawn into the third flow path 23 from the outside of the lower casing 14. Therefore, the amount of vapor discharged from the vapor discharge hole 20 can be increased.

(6) In the present embodiment, the first flow path 21 of the vapor discharge hole 20 is connected to an inner curved surface portion 183 provided on the inner diameter side of the fuel flow path 18.
Since the centrifugal force due to the rotation of the impeller 11 acts on the fuel flowing through the fuel flow path 18, the pressure of the fuel flowing radially outside the fuel flow path 18 is high. For this reason, the vapor contained in the fuel has a mass smaller than that of the fuel, and therefore flows inside the fuel flow path 18 in the radial direction. Therefore, by connecting the first flow path 21 of the vapor discharge hole 20 to the inner curved surface portion 183 of the fuel flow path 18, the vapor flowing through the fuel flow path 18 can be reliably introduced into the vapor discharge hole 20.

(Second Embodiment)
An enlarged view of the main part of the fuel pump of the second embodiment is shown in FIG. Hereinafter, in the plurality of embodiments, substantially the same configurations as those in the first embodiment described above are denoted by the same reference numerals, and description thereof is omitted.
In the second embodiment, the vapor discharge hole 20 is connected to the inner circumference on the inner diameter side of the first taper portion 25 and the inner circumference on the fuel flow path side of the second flow path. Therefore, the first taper portion 25 of the vapor discharge hole 20 is provided in all of the steps provided between the first flow path 21 and the second flow path 22. Therefore, in the second embodiment, there is no step between the first flow path 21 and the second flow path 22.
Also in the second embodiment, the first taper portion 25 prevents vortex from being generated in the fuel flowing from the first flow path 21 to the second flow path 22. Therefore, the fuel can flow through all the flow paths of the vapor discharge hole 20, and the vapor of the fuel flow path 18 can be reliably discharged from the vapor discharge hole 20.

(Third embodiment)
The principal part enlarged view of the fuel pump of 3rd Embodiment is shown in FIG. In the third embodiment, the first tapered portion 26 of the vapor discharge hole 20 is connected to the fuel flow path 18.
Also in the third embodiment, there is no step between the first flow path 21 and the second flow path 22, and a vortex is generated in the fuel flowing from the first flow path 21 or the first tapered portion 26 to the second flow path 22. It is prevented. Therefore, the vapor of the fuel flow path 18 can be reliably discharged from the vapor discharge hole 20.

(Other embodiments)
(1) In the above-described embodiment, the fuel pump used in the variable fuel pressure system has been described. On the other hand, in other embodiments, the fuel pump can be used in a general fuel supply system.
(2) In the above-described embodiment, the fuel pump including the brushless motor has been described. On the other hand, in other embodiments, the fuel pump may include a motor with a brush.

(3) In the above-described embodiment, the vapor discharge hole has the first flow path, the second flow path, the third flow path, and the first tapered portion. On the other hand, in another embodiment, the vapor discharge hole may have a configuration in which the second flow path directly opens on the outer wall of the lower casing 14 without having the third flow path.
The present invention is not limited to the above-described embodiment. In addition to combining the above-described plurality of embodiments, the present invention can be implemented in various forms without departing from the spirit of the invention.

DESCRIPTION OF SYMBOLS 1 ... Fuel pump 11 ... Impeller 13 ... Upper casing (casing)
14 ... Lower casing (casing)
16 ... pump chambers 18, 19 ... fuel flow path 20 ... vapor discharge hole 21 ... first flow path 22 ... second flow paths 24, 25, 26 ... first taper portion

Claims (6)

An impeller (11) having a plurality of blade grooves in the circumferential direction;
A motor unit (30) for rotating the impeller;
A casing (13, 14) having a pump chamber (16) for rotatably accommodating the impeller;
An inlet (12) for introducing fuel into the pump chamber from the outside of the casing;
A discharge port (17) for discharging fuel from the pump chamber to the outside of the casing;
A fuel flow path (18, 19) formed annularly in the casing corresponding to the blade groove of the impeller from the suction port to the discharge port;
First flow path which communicates with the fuel passage (21), its inner diameter than the first flow path is smaller second flow path communicating with the counter-fuel flow path side of said first flow path (22), and , Having a first tapered portion (24, 25, 26) provided at a connection portion between the first flow path and the second flow path, and capable of discharging vapor from the fuel flow path to the outside of the casing. A vapor discharge hole (20) ,
When the distance from the connection position between the fuel flow path and the first flow path to the connection position between the first flow path and the second flow path is L and the inner diameter of the first flow path is d, 2 ≦ d / L ≦ 5 der Rukoto fuel pump according to claim (1).   2. The fuel pump according to claim 1, wherein the vapor discharge hole further includes a planar and annular step provided between the first tapered portion and the second flow path. Wherein the first flow path and the second flow path and the first tapered portion, the fuel pump according to claim 1 or 2, characterized in that provided coaxially. The vapor discharge hole further includes a third channel (23) communicating with the second channel on the side opposite to the first channel,
The fuel pump according to any one of claims 1 to 3, wherein an inner diameter of the third flow path is larger than an inner diameter of the second flow path.   The inner wall of the third flow path has a taper of about a draft angle for pulling out a mold forming the third flow path from a material constituting the casing when forming the casing. Item 5. The fuel pump according to Item 4. The fuel flow path is
An outer curved surface portion (181) that gradually becomes deeper from the outside diameter toward the inside diameter;
A flat surface portion (182) provided on the inner diameter side of the outer curved surface portion and having a constant depth;
An inner curved surface portion (183) which is provided on the inner diameter side of the flat surface portion and gradually becomes shallower from the flat surface toward the inner diameter side,
The fuel pump according to any one of claims 1 to 5, wherein the first flow path of the vapor discharge hole is connected to the inner curved surface portion.

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