JP2005090340A - Fuel pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide technology for improving durability of a fuel pump. <P>SOLUTION: A group of recessed parts repeating in the peripheral direction across a bulkhead extending in the radial direction in a region extending in the peripheral direction across predetermined distance onto an inner side from the outer periphery are formed on both front and rear faces of an impeller 20 in the impeller 20 of the fuel pump 10. Bottom parts of the recessed parts on the front and rear faces of the impeller 20 are mutually communicated. A surface side channel 30 extending from an upstream side end to a downstream side end in a region opposing to the group of recessed parts on a surface side is formed on an inner face of a casing 18 opposing to a surface of the impeller 20. A rear face side channel 24 extending from an upstream side end to a downstream side end in a region opposing to the group of recessed parts on a rear face side is formed on the inner face of the casing 18 opposing to a rear face of the impeller 20. A suction flow passage communicating with both of the upstream side end of the surface side channel 30 and the upstream side end of the rear face side channel 24 from the outside of the casing 18 and a casing inner peripheral face opposing to an outer peripheral face of the impeller 20 over the whole periphery are formed in the casing 18. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a fuel pump that sucks fuel such as gasoline and boosts the pressure, and discharges the boosted fuel. In particular, the present invention relates to a technique for improving the durability of a fuel pump.

There is known a fuel pump including a substantially disk-shaped impeller that rotates in a casing. In a region extending in the circumferential direction with a predetermined distance inward from the outer periphery of the impeller, concave groups that repeat in the circumferential direction with a partition wall extending in the radial direction are formed on both front and back surfaces of the impeller. The bottom side of the recess on the front side and the recess on the back side of the impeller are communicated with each other through a communication hole. The recess group is separated from the outer peripheral surface of the impeller by the outer peripheral wall of the impeller. On the inner surface of the casing facing the surface of the impeller, a surface-side groove extending from the upstream end to the downstream end is formed in a region facing the surface-side recess group. On the inner surface of the casing facing the back surface of the impeller, a back surface side groove is formed extending from the upstream end to the downstream end in a region facing the back surface side recess group. The casing is formed with a suction flow path communicating from the outside of the casing to the upstream end of the front side groove and a discharge flow path communicating from the downstream end of the back side groove to the outside of the casing.
When the impeller rotates, fuel is sucked into the suction flow path, and a swirling flow is generated across each surface-side recess and the surface-side groove. In addition, a swirl flow is generated even when straddling each backside recess and the backside groove. The sucked fuel is pressurized while flowing from the upstream end to the downstream end of the front surface side groove and the back surface side groove. The fuel in the front side groove flows through the recess communication hole and flows into the back side groove. The pressurized fuel is discharged out of the casing from the discharge passage. When the fuel passes through the communication hole in the recess, the swirl flow is less likely to occur. If the swirl flow is less likely to occur, the boosting performance will not increase.
A technique for solving this problem is described in Patent Document 1. In the fuel pump according to the technique described in Patent Document 1, the suction flow path is connected to the upstream end sides of both the front surface side groove and the back surface side groove. If comprised in this way, the amount of fuel which passes the communicating hole of the recess of an impeller will decrease. When the amount of fuel passing through the communication hole is reduced, a swirl flow is likely to occur, and the pressure increase performance is improved. Therefore, the discharge pressure of the fuel pump can be increased.
Japanese Patent Laid-Open No. 7-4376

In the fuel pump described in Patent Document 1, the casing inner peripheral surface facing the outer peripheral surface of the impeller is partially engraved, and that portion constitutes a part of the suction flow path. The upstream end side of the front surface side groove communicates with the upstream end side of the back surface side groove by the portion in which the casing inner peripheral surface is carved. In such a configuration, an imbalance of the acting fuel pressure occurs between a portion corresponding to a portion of the outer peripheral surface of the impeller that is engraved with the outer peripheral surface of the casing and a portion that is not engraved. For this reason, a force in a direction perpendicular to the axis acts on the shaft supporting the impeller. When a force in a certain direction acts on the shaft, the life of the bearing interposed between the shaft and the casing is reduced.
The present invention has been made to solve such a problem, and an object of the present invention is to provide a technique for improving the durability of the fuel pump.

A fuel pump created to solve the above-described problem includes a substantially disk-shaped impeller that rotates within a casing. In a region extending in the circumferential direction with a predetermined distance inward from the outer periphery of the impeller, concave groups that repeat in the circumferential direction with a partition wall extending in the radial direction are formed on both front and back surfaces of the impeller. The bottoms of the recesses on the front and back of the impeller communicate with each other. The recess group is separated from the outer peripheral surface of the impeller by the outer peripheral wall of the impeller. On the inner surface of the casing facing the surface of the impeller, a surface-side groove extending from the upstream end to the downstream end is formed in a region facing the surface-side recess group. On the inner surface of the casing facing the back surface of the impeller, a back surface side groove is formed extending from the upstream end to the downstream end in a region facing the back surface side recess group. The casing is formed with a suction passage communicating from the outside of the casing to both the upstream end of the front surface side groove and the upstream end of the back surface side groove, and a casing inner peripheral surface facing the impeller outer peripheral surface over the entire circumference.
The fuel pump casing is formed with a suction flow path communicating from the outside of the casing to both the upstream end of the front surface side groove and the upstream end of the back surface side groove, and a casing inner peripheral surface facing the impeller outer peripheral surface over the entire circumference. Has been. For this reason, the force which acts on the outer peripheral surface of an impeller does not become unbalanced. For this reason, a force in a direction perpendicular to the axis does not act on the shaft supporting the impeller. Therefore, the durability of the fuel pump is improved.

In the above fuel pump, the front side suction flow path communicating from the outside of the casing to the upstream end of the front side groove and the back side suction flow path communicating from the outside of the casing to the upstream end of the back side groove are provided independently. preferable.
If the front-side suction flow path and the back-side suction path are provided independently, the fuel sucked into the front-side groove and the back-side groove is prevented from exerting influences such as pulsation on each other.

(Form 1)
2. The fuel pump according to claim 1, wherein a downstream side of the suction passage is branched and connected to an upstream end side of the front surface side groove and the back surface side groove.
If comprised in this way, the flow-path cross-sectional area of the suction flow path upstream from a branch part can be ensured large. Therefore, the pressure loss generated in the suction flow path can be reduced.
(Form 2)
The width of the groove is larger than the width of the suction channel when the connection portion between the suction channel and the groove is viewed in a cross-section in the direction perpendicular to the longitudinal direction of the groove. The fuel pump described in 1.
The groove width is formed larger than the suction channel width at the connection portion between the suction channel and the groove. When fuel flows into the groove from the suction channel, the swirl flow can be made stronger.

An embodiment according to the fuel pump 10 of the present invention will be described with reference to the drawings. The fuel pump 10 is for an automobile, operates in a state immersed in the fuel in the fuel tank, and pumps the fuel to the engine.
As shown in FIG. 1, the fuel pump 10 includes a motor unit 70 and a pump unit 12. The motor unit 70 includes a housing 72, a motor cover 73, magnets 74 and 75, a rotor 76, and the like. The housing 72 is formed in a substantially cylindrical shape. The motor cover 73 is fixed to the housing 72 by caulking the upper end 72a of the housing 72 (the upper and lower sides in FIG. 1 are the upper and lower sides of the fuel pump 10) toward the inner diameter side. The motor cover 73 is formed with a discharge port 73a that opens upward.
The magnet 74 and the magnet 75 are for the N pole and the S pole, respectively, and are fixed to the inner wall of the housing 72. The rotor 76 includes a main body 77 and a shaft 78 that penetrates the main body 77 up and down. The main body 77 has an iron core 79 fixed to the shaft 78, a coil (not shown) wound around the iron core 79, and a cylindrical shape in which the outer shape of the main body 77 coincides with the iron core 79. Thus, the resin part 80 formed is provided. An upper end portion 78 a of the shaft 78 is rotatably attached to the motor cover 73 via a bearing 81. A lower end portion 78 b of the shaft 78 is rotatably mounted on a pump cover 14 (described later) of the pump portion 12 via a bearing 82.
Further, the motor cover 73 is provided with a terminal 83 to which an external power supply connector is connected, and a brush 84 connected to the terminal 83. The brush 84 is urged by the spring 85 and is pressed against the upper end surface 79 a of the iron core 79. Even if the rotor 76 rotates and the upper end surface 79a of the iron core 79 and the brush 84 slide and the brush 84 is worn, the spring 85 presses the brush 84 against the upper end surface 79a. Will make a reliable contact.
When electric power is supplied to the terminal 83 from the outside, the rotor 76 rotates.

The pump unit 12 includes a casing 18, an impeller 20, and the like. The casing 18 is a combination of the pump cover 14 and the pump body 16.
The impeller 20 has a substantially disk shape, and a plurality of recesses 20a arranged in the circumferential direction are formed on the outer peripheral portion thereof as shown in FIG. As well shown in FIG. 3, the recesses 20a are formed on the upper and lower surfaces of the impeller 20, and the recesses 20a are communicated with each other through the communication hole 20b at the bottom. As shown in FIG. 2, an engagement hole 20 c having a substantially D-shaped cross section perpendicular to the axis passing through in the thickness direction is formed at the center of the impeller 20.
FIG. 4 is a schematic perspective view of the pump cover 14 alone. The pump cover 14 is formed with a recess 22 that opens to the lower end surface 14a. The depth and diameter of the recess 22 are slightly larger than the thickness and diameter of the impeller 20. The impeller 20 is assembled in the recess 22.
As well shown in FIG. 5, a cover-side groove 24 extending in the circumferential direction is formed on the bottom surface 22 a of the recess 22 over substantially ¾ of the circumference. The cover side groove 24 is formed in a region facing the recess 20 a of the impeller 20 incorporated in the recess 22.
The lower end surface 14 a of the pump cover 14 and one end 24 a of the cover side groove 24 are communicated with each other by a cover side flow path 26. The cover-side channel 26 is directed upward from the lower end surface 14a of the pump cover 14, is bent toward the center of the pump cover 14 at a position above the bottom surface 22a of the recess 22, and is further bent downward. It reaches one end 24 a of the cover side groove 24. As shown in FIGS. 1 and 5, a discharge flow path 28 that penetrates the pump cover 14 vertically is provided. The lower end of the discharge channel 28 opens to the other end 24 b of the cover side groove 24.

FIG. 6 is a schematic perspective view of the pump body 16 alone. A body side groove 30 is formed on the upper surface 16 a of the pump body 16. The body side groove 30 is formed in a region facing the cover side groove 24 of the pump cover 14 with the impeller 20 interposed therebetween. A first body-side flow path 32 that penetrates the pump body 16 up and down is provided. The upper end of the first body side channel 32 is open to one end 30 a of the body side groove 30. Outside the first body side channel 32, a second body side channel 31 penetrating the pump body 16 vertically is provided. In a state where the pump cover 14 and the pump body 16 are combined, the cover-side flow path 26 and the second body-side flow path 31 are connected.
The casing 18 (the pump cover 14 and the pump body 16) is fixed to the housing 72 by crimping the lower end 72b of the housing 72 inward while the impeller 20 is assembled in the recess 22 of the pump cover 14. Yes. The shaft 78 of the rotor 76 is inserted in a state where the shaft 78 of the rotor 76 is engaged with the engagement hole 20c of the impeller 20 further below the portion supported by the bearing 82. For this reason, when the rotor 76 rotates, the impeller 20 also rotates with it. A thrust bearing 33 is interposed between the lower end of the shaft 78 and the pump body 16 to receive the thrust load of the rotor 76.
In a state in which the impeller 20 is assembled in the casing 18, a flow path is formed from the first body side flow path 32 of the pump body 16 to the one end 30 a of the body side groove 30 and then along the body side groove 30 to the discharge flow path 28. Is done. In addition, a flow path is formed from the body side groove 30 through the communication hole 20 b formed in the recess 20 a of the impeller 20 from below to the cover side groove 24 and further to the discharge flow path 28. Further, the flow path reaches from the second body side flow path 31 of the pump body 16 through the cover side flow path 26 of the pump cover 14 to the one end 24a of the cover side groove 24 and extends along the cover side groove 24 to the discharge flow path 28. Is formed.

  When the impeller 20 rotates, a swirling flow is generated that spans the fuel entering the recess 20a on the lower side (body side groove 30 side) and the fuel filled in the body side groove 30 of the pump body 16. The fuel flows along the body side groove 30 while turning and is pressurized. When the pressure of the fuel is increased along the body side groove 30, the fuel is sucked into the first body side flow path 32 of the pump body 16 accordingly. In addition, a swirling flow is also generated across the recess 20 a on the upper side of the impeller 20 (the cover side groove 24 side) and the fuel filled in the cover side groove 24 of the pump cover 14, whereby the fuel flows along the cover side groove 24. While being boosted. When the pressure of the fuel is increased along the cover side groove 24, the fuel is sucked into the second body side channel 31 of the pump body 16, the cover side channel 26 and the second body side channel 31 of the pump cover 14. It is. The fuel pressurized in the body side groove 30 passes through the communication hole 20 a of the impeller 20 and merges with the fuel pressurized in the cover side groove 24. The fuel pressurized in the cover side groove 24 and the fuel pressurized in the body side groove 30 joined therewith are sent out from the discharge passage 28 into the housing 72 of the motor unit 70. The fuel fed into the housing 72 flows upward in the housing 72 and is discharged from the discharge port 73 a of the motor cover 73.

Thus, in the fuel pump 10 of the present embodiment, the first body side flow path 32 is connected to the one end 30 a of the body side groove 30 of the pump body 16. A cover-side flow path 26 is connected to one end 24 a of the cover-side groove 24 of the pump cover 14. A second body side flow path 31 of the pump body 16 is connected to the cover side flow path 26. The cover-side channel 26 and the second body-side channel 31 form a suction channel that connects the cover-side groove 24 and the outside of the casing 18.
If the cover-side flow path 26 and the second body-side flow path 31 are not provided, the fuel sucked by the impeller 20 is directed from the bottom upward to the communication hole 20b formed in the recess 20a of the impeller 20. Must pass through. If all of the fuel must pass through the communication hole 20b of the recess 20a, the pressure loss during the passage increases. When the pressure loss is increased, the efficiency of the fuel pump 10 is deteriorated (the discharge pressure of the fuel pump 10 is decreased). Further, if the pressure loss in the communication hole 20b is large, the pressure difference between before and after it becomes large, so that vapor (bubbles) is generated when the temperature of the fuel is high. When the vapor is generated, the impeller 20 stirs the gas, and the efficiency of the fuel pump 10 is deteriorated.
In the fuel pump 10 of the present embodiment, the fuel suction flow path (the first body side flow path 32, the second body side flow path 31 and the cover side flow path 26) is independent of each of the body side groove 30 and the cover side groove 24. Is provided. For this reason, all of the fuel sucked into the fuel pump 10 does not need to pass through the communication hole 20b of the recess 20a. That is, the amount of fuel passing through the communication hole 20b of the recess 20a is small. For this reason, the pressure loss generated in the communication hole 20b is reduced, and as a result, the efficiency of the fuel pump 10 is improved. Further, when the amount of fuel passing through the communication hole 20b is small and the pressure loss is small, the generation of vapor is suppressed. Further, when the amount of fuel passing through the communication hole 20b is small, the swirl flow generated across the fuel in the recess 20a and the grooves 24 and 30 becomes stronger. This is because the degree to which the swirling flow is disturbed by the fuel passing through the communication hole 20b is reduced. As the swirl flow becomes stronger, the fuel is further pressurized. Therefore, the efficiency of the fuel pump 10 is improved.
In the fuel pump 10, the first body side channel 32, the second body side channel 31, and the cover side channel 26 are separated (each independent). With this configuration, the fuel sucked into the body side groove 30 and the fuel sucked into the cover side groove 24 can be prevented from affecting each other such as pulsation.

As shown in FIG. 7, in the fuel pump 10 of this embodiment, the outer peripheral surface 20 d of the impeller 20 and the cover-side flow path 26 are separated by a partition wall 34 formed integrally with the pump cover 14. It has been. For this reason, the outer peripheral surface 20d of the impeller 20 is covered with the inner peripheral surface 22b of the recessed part 22 over the whole.
As in the embodiment shown in FIG. 8, the cover-side flow path 26 can be easily processed without providing the partition wall 34. If the partition wall 34 is provided, the cover-side channel 26 must be processed as a passage hole, but if the partition wall 34 is not provided, the cover-side channel 26 can be formed simply by engraving the recess 22. It is. However, if the partition wall 34 is not provided, the inner peripheral surface 22b of the recess 22 is cut out at that portion. The fuel flowing through the cover side channel 26 is sucked by the impeller 20. Therefore, the pressure acting on the portion corresponding to the portion where the inner peripheral surface 22b of the recess 22 of the outer peripheral surface 20d of the impeller 20 is cut out (the cover-side flow path 26) and the portion corresponding to the inner peripheral surface 22b is unmeasured. Balance arises. Then, a force in a certain direction acts on the shaft 78 supporting the impeller 20 in a direction perpendicular to the axis. When a force in a direction perpendicular to the axis acts on the shaft 78, a backlash is generated in the bearing 82 that rotatably supports the shaft 78. If play occurs in the bearing 82, its life is shortened. Further, when play occurs in the bearing 82, the outer peripheral surface 20d of the impeller 20 and the inner peripheral surface 22b of the recess 22 come into contact with each other. When the outer peripheral surface 20d and the inner peripheral surface 22b come into contact with each other, the inner peripheral surface 22b is partially worn (only a part of the inner peripheral surface 22b is worn). Like the fuel pump 10 of the present embodiment, by providing the partition wall 34 that separates the outer peripheral surface 20d of the impeller 20 and the cover-side flow path 26, it is possible to prevent the force in the direction perpendicular to the shaft from acting on the shaft due to the fuel pressure. Therefore, it is possible to prevent the backlash from occurring in the bearing 82 and uneven wear of the inner peripheral surface 22b of the recess 22. Therefore, the durability of the fuel pump 10 is improved.

As shown in FIG. 9, the first body side flow path 32 and the second body side flow path 31 of the pump body 16 can also be configured to branch within the pump body 16. In this way, a large cross-sectional area of the flow path in the pump body 16 can be ensured. Therefore, the pressure loss generated in the flow path in the pump body 16 can be reduced. Moreover, according to this structure, the flow path inlet of the pump body 16 becomes one. For this reason, when a filter is attached to the flow path inlet of the pump body 16, the configuration of the filter can be simplified.
As shown in FIG. 10, the second body-side flow path 31 of the pump body 16 may not be provided, and the upstream end of the cover-side flow path 26 may be configured to open to the side surface of the pump cover 14. If comprised in this way, the upstream flow path of the cover side groove | channel 24 becomes only the cover side flow path 26, and becomes short. For this reason, the pressure loss which arises between the exterior and the cover side groove | channel 24 can be made small. When the pressure loss is reduced, the efficiency of the fuel pump 10 is improved. Further, according to this configuration, the difference in length between the cover-side channel 26 and the first body-side channel 32 is reduced. For this reason, the difference of the pressure loss which arises in the cover side flow path 26 and the 1st body side flow path 32 becomes small. Therefore, the amount of fuel sucked into the cover side groove 24 and the body side groove 30 can be prevented from becoming unbalanced.
As shown in FIG. 11, the outer wall of the second body side flow path 31 of the pump body 16 and the cover side flow path 26 of the pump cover 14 can also be used by the housing 72. If comprised in this way, when processing the 2nd body side flow path 31 and the cover side flow path 26, it is sufficient to carve the pump body 16 and the pump cover 14 inward. That is, it is not necessary to drill holes in the second body side channel 31 and the cover side channel 26, and the processing becomes easy.
As shown in FIG. 12, a flow path 36 penetrating up and down the pump body 16 is provided, and the flow path 36 is disposed upstream of the body side groove 30 and the cover side flow path 26, and A part of the outer wall and the outer wall of the cover-side flow path 26 can also be configured to be shared by the housing 72. If it does in this way, the pressure loss can be made small by ensuring the cross-sectional area of the flow path 36 large. Further, when the cover-side flow path 26 is processed, it is only necessary to engrave the pump cover 14 on the inner side. For this reason, the process of the cover side flow path 26 becomes easy.

As shown in FIG. 13, the first body side flow path 32 and the cover side flow path 26 are respectively “W1> W2” with respect to the body side groove 30 of the pump body 16 and the cover side groove 24 of the pump cover 14. And can be configured to be offset in the width direction with respect to the grooves 24 and 30. The cover-side flow path 26 is bent from the opening provided on the lower end surface of the pump cover 14 toward the upper side, is bent toward the inner side of the pump cover 14, and is further bent at the lower side to form the cover-side groove 24. It is connected. With this configuration, as indicated by arrows in FIG. 13, the recess 20a of the impeller 20 is caused by the fuel flowing into the body side groove 30 and the cover side groove 24 from the first body side flow path 32 and the cover side flow path 26, respectively. The swirling flow generated across the grooves 24 and 30 can be swirled more strongly. For this reason, the pressure of the fuel is further increased.
In the form shown in FIG. 14, the connection state between the first body-side flow path 32 and the body-side groove 30 of the pump body 14 is the same as that in FIG. 13. The cover-side flow path 26 is bent from the opening provided on the lower end surface of the pump cover 14 toward the upper side and is directed inward of the pump cover 14, and is connected to the cover-side groove 24. In this case, the fuel flowing into the cover-side groove 24 from the cover-side channel 26 flows into the recess 20 a on the upper side of the impeller 20 after the flow direction is bent downward along the wall surface of the cover-side groove 24. . For this reason, the swirl flow spanning the recess 20a on the upper side of the impeller 20 and the cover side groove 24 swirls more strongly. In this case, it is preferable that W2 and W3 are substantially equal.
In the form shown in FIG. 15, the shapes of the cover-side flow path 26 and the cover-side groove 24 of the pump cover 14 are the same as those in FIG. The first body side flow path 32 and the second body side flow path 31 are branched in the pump body 16. If comprised in this way, the flow-path cross-sectional area can be enlarged rather than providing the 1st body side flow path 32 and the 2nd body side flow path 31 separately. For this reason, the pressure loss of the 1st body side channel 32 and the 2nd body side channel 31 can be made small. Further, as shown in FIG. 15, when the first body side channel 32 is narrowed as it approaches the body side groove 30, the fuel flowing through the first body side channel 32 is accelerated. When the fuel flowing through the first body side flow path 32 is accelerated, the fuel flows into the body side groove 30 vigorously. Therefore, the swirl flow generated across the recess 20a on the lower side of the impeller 20 and the body side groove 30 can be made stronger.

Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.
In addition, the technical elements described in the present specification or drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology illustrated in the present specification or the drawings achieves a plurality of objects at the same time, and has technical utility by achieving one of the objects.

The longitudinal cross-sectional view of the fuel pump which concerns on an Example. The top view of the impeller which concerns on an Example. III-III sectional view taken on the line of FIG. The typical perspective view of the pump cover which concerns on an Example. The VV arrow directional view of FIG. The typical perspective view of the pump body which concerns on an Example. The enlarged view of the suction part of the casing and impeller which concerns on an Example. The casing which concerns on an Example and one form of the suction part of an impeller are shown. Same as above. Same as above. Same as above. Same as above. Same as above. Same as above. Same as above.

Explanation of symbols

10: Fuel pump 12: Pump part 14: Pump cover, 14a: Lower end surface 16: Pump body, 16a: Upper surface 18: Casing 20: Impeller, 20a: Recess, 20b: Communication hole, 20c: Engagement hole, 20d: Outer peripheral surface 22: recess, 22a: bottom surface 24: cover side groove, 24a: one end, 24b: other end 26: cover side flow channel 28: discharge flow channel 30: body side groove, 30a: one end 31: second body side flow channel 32 : 1st body side flow path 33: Thrust bearing 70: Motor part 72: Housing, 72a: Upper end, 72b: Lower end 73: Motor cover, 73a: Discharge port 74, 75: Magnet 76: Rotor 77: Main body 78: Shaft 78a: upper end portion, 78b: lower end portion 79: iron core, 79a: upper end surface 80: resin portion 81, 82: bearing 83: terminal 84: brush 85: spray Grayed

Claims (2)

Provided with a substantially disk-shaped impeller rotating in the casing,
In the region extending in the circumferential direction with a predetermined distance inward from the outer periphery of the impeller, recesses that repeat in the circumferential direction with a radially extending partition wall are formed on both the front and back surfaces of the impeller. The bottoms of each other are in communication with each other, and the recesses are separated from the outer peripheral surface of the impeller by the outer peripheral wall of the impeller.
A surface side groove extending from an upstream end to a downstream end in a region facing the surface side recess group is formed on the inner surface of the casing facing the surface of the impeller, and a back surface side recess group is formed on the casing inner surface facing the back surface of the impeller. A rear surface side groove extending from the upstream end to the downstream end is formed in the region facing the
The casing is formed with a suction flow path communicating with both the upstream end of the front surface side groove and the upstream end of the back surface side groove from the outside of the casing, and a casing inner peripheral surface facing the impeller outer peripheral surface over the entire circumference. A fuel pump characterized by   2. The front-side suction passage that communicates from the outside of the casing to the upstream end of the front-side groove and the back-side suction passage that communicates from the outside of the casing to the upstream end of the rear-side groove are provided independently. The fuel pump described in 1.

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