JP4489450B2 - Fuel pump - Google Patents

Description

  The present invention relates to a fuel pump that sucks fuel such as gasoline and boosts the pressure, and discharges the boosted fuel.

There is known a fuel pump including a substantially disc-shaped impeller and a casing that rotatably accommodates the impeller. A typical fuel pump configuration is described below. An example of a conventional fuel pump is described in Patent Document 1.
-On the outer periphery of the impeller, concave groups that repeat in the circumferential direction are formed on both the front and back surfaces of the impeller.
A first groove extending from an upstream end to a downstream end in a region facing the outer periphery of the impeller is formed on the inner surface of the casing facing the impeller surface.
A second groove extending from the upstream end to the downstream end in a region facing the outer periphery of the impeller is formed on the inner surface of the casing facing the back surface of the impeller.
The casing is formed with a fuel intake passage that communicates the vicinity of the upstream end of the first groove and the outside of the casing, and a fuel discharge passage that communicates the vicinity of the downstream end of the second groove and the outside of the casing. Yes.
-In the region downstream from the downstream end of the first groove and the second groove and upstream from the upstream end, the casing inner surface is very close to the outer periphery of the impeller, and between the downstream end and the upstream end of the first groove and the second groove. Are substantially separated. The casing inner surface that is very close to the outer periphery of the impeller and substantially separates between the downstream end and the upstream end of the first groove and the second groove is referred to as a radial seal.

In the fuel pump having the above-described configuration, when the impeller rotates, fuel is sucked into the casing from the fuel suction passage. The sucked fuel is introduced into a recess on the outer periphery of the impeller. Centrifugal force resulting from the rotation of the impeller acts on the fuel in the recess, and a swirl flow that spans the front-side recess and the first groove of the impeller and a swirl flow that straddles the back-side recess and the second groove are generated. The fuel sucked into the casing advances downstream along the first groove and the second groove while forming a swirling flow. In this process, the pressure of the fuel is increased, and the pressurized fuel is discharged out of the casing from the fuel discharge passage.
The fuel pump of this configuration needs to prevent the pressurized fuel at the downstream ends of the first groove and the second groove from leaking to the upstream ends of the first groove and the second groove. The shape accuracy of the radial seal that substantially separates the downstream end and the upstream end of the two grooves is directly connected to the pump performance.
In the fuel pump of the type in which the recesses of the impeller are opened to the outer periphery and the downstream end and the upstream end of the first groove and the second groove are separated by a radial seal, extremely high form accuracy to stabilize the pump performance The production cost cannot be reduced.

Therefore, a fuel pump described in Patent Document 2 has been developed. The configuration of the fuel pump will be described below.
In the region extending in the circumferential direction at a predetermined distance from the outer periphery of the impeller to the inner peripheral side, recess groups that repeat in the circumferential direction are formed on both the front and back surfaces of the impeller. That is, the recess group is not opened to the outer periphery of the impeller, but is separated from the outer peripheral surface of the impeller by the outer peripheral wall of the impeller. The bottoms of the front and back recesses communicate with each other.
A first groove extending from the upstream end to the downstream end in a region facing the concave group of the impeller is formed on the inner surface of the casing facing the impeller surface.
A second groove extending from the upstream end to the downstream end is formed on the inner surface of the casing facing the back surface of the impeller.
The casing is formed with a fuel intake passage that communicates the vicinity of the upstream end of the first groove and the outside of the casing, and a fuel discharge passage that communicates the vicinity of the downstream end of the second groove and the outside of the casing. Yes.
-The fuel discharge flow path is opened in the casing inner surface facing the back surface of an impeller.

In the fuel pump having the above-described configuration, when the impeller rotates, fuel is sucked into the casing from the fuel suction passage. The sucked fuel is introduced into the recess on the surface side of the impeller. Centrifugal force caused by the rotation of the impeller acts on the fuel in the recess, and a swirling flow is generated across the recess on the surface side of the impeller and the first groove. This swirl flow enters the inner peripheral side in the surface side recess from the first groove, flows in the surface side recess from the inner peripheral side to the outer peripheral side, and returns to the first groove from the outer peripheral side in the surface side recess. Form a road. Further, since the recesses on the front and back sides of the impeller are in communication, the fuel is also introduced into the recess on the back surface side of the impeller, and a swirling flow extending over the back surface recess and the second groove is also generated. This swirl flow enters the inner peripheral side in the back side recess from the second groove, flows in the back side recess from the inner peripheral side to the outer peripheral side, and returns to the second groove from the outer peripheral side in the back side recess. Form a road.
The fuel sucked into the casing advances downstream along the first groove and the second groove while forming a swirling flow. In this process, the pressure of the fuel is increased, and the pressurized fuel is discharged out of the casing from the fuel discharge passage.

With reference to FIGS. 14 and 15, the configuration of the above-described fuel discharge channel will be described in a little more detail. FIG. 14 is an enlarged view of the vicinity of the fuel discharge passage when the inner surface of the casing facing the back surface of the impeller is viewed in plan. 15 is a cross-sectional view taken along line XV-XV in FIG.
Reference numeral 514 is a part of the casing, reference numeral 524 is a second groove, and reference numeral 526 is a fuel discharge passage. FIG. 15 clearly shows that the fuel discharge channel 526 is open with respect to the inner surface of the casing (the opening is indicated by a broken line and denoted by reference numeral 527). Reference numeral 527a indicates the innermost boundary of the opening 527 of the fuel discharge channel 526 on the inner surface of the casing facing the back surface of the impeller 20 (upper surface in FIG. 15). Reference numeral 527 b indicates the outermost boundary of the opening 527 of the fuel discharge channel 526 on the inner surface of the casing facing the back surface of the impeller 20. As can be seen from FIG. 15, the inner boundary 527 a described above is located at the same position as the inner peripheral end of the recess 20 a of the impeller 20, and the outer boundary 527 b is connected to the outer peripheral end of the recess 20 a of the impeller 20. It is in the same position.
Reference numeral 20d denotes an outer peripheral wall extending in a ring shape on the outer peripheral side of the recess group. Since the recess group is not open to the outer periphery, a radial seal is not required.
JP 10-213089 A JP 2000-329085 A

In the case of the conventional fuel pump described above, as shown by the arrow D1 ′ in FIG. 15, a swirling flow that spans the fuel discharge passage 526 and the recess 20a is generated. By generating this swirl flow D1 ′, a fuel flow (arrow DX) toward the impeller 20 is generated in the fuel discharge passage 526. In the fuel discharge flow path 526, the fuel flow in the counter-discharge direction is formed, so that the fuel does not flow smoothly in the discharge direction. For this reason, the boosting performance is degraded.
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a technique capable of smoothly flowing fuel in a discharge direction in a fuel discharge channel. As a result, a fuel pump having an excellent boosting performance is realized.

The fuel pump of the present invention includes an impeller in which a plurality of recess groups are formed in an annular shape, and a casing that rotatably accommodates the impeller. A first groove that communicates with the fuel intake passage and a second groove that communicates with the fuel discharge passage are formed in the “region facing the recess group of the impeller” of the casing. The first boundary on the innermost peripheral side of the opening of the fuel discharge channel is at a substantially intermediate position in the radial direction of the recess group of the impeller. Outermost peripheral side second boundary of the opening of the fuel discharge passage is on the inner circumferential side of the outer peripheral surface of the impeller to a peripheral end by Ri outer peripheral side of the recess group of the impeller. The side surface on the inner peripheral side of the fuel discharge channel extends from the first boundary perpendicularly to the back surface of the impeller or inclined toward the inner peripheral side.

The above-mentioned “substantially intermediate position in the radial direction of the recess group of the impeller” is not limited to being the center position in the radial direction of the recess group of the impeller. The position where the technology of the present invention effectively functions is “a substantially intermediate position in the radial direction of the recess group of the impeller”, for example, the distance between the inner peripheral end and the outer peripheral end of the impeller recess group. When 1/4 is the specific distance, the position on the outer peripheral side by a specific distance from the inner peripheral end of the recess group of the impeller, and the position on the inner peripheral side by a specific distance from the outer peripheral end of the recess group of the impeller Any position between. Among these, it is preferable to adopt the position in the middle of the recess group of the impeller in the radial direction as the “substantially intermediate position in the radial direction of the recess group of the impeller”.
In the fuel pump of the present invention, the first boundary is at a substantially intermediate position in the radial direction of the recess group of the impeller, and the fuel discharge passage is not open on the inner peripheral side from the substantially intermediate position. Therefore, the flow of fuel from the fuel discharge passage toward the inner peripheral side of the impeller recess is hardly formed. Since no fuel flow in the anti-discharge direction is formed in the fuel discharge flow path, the fuel can flow smoothly in the fuel discharge flow path in the discharge direction. The fuel pump of the present invention exhibits excellent boosting performance because there is no loss of fuel flow in the fuel discharge passage.

The larger the opening of the fuel discharge channel, the more smoothly the fuel can be discharged. If to secure a large opening of the fuel discharge passage, the first boundary, it is preferable to be formed in an arc shape along a substantially intermediate position in the radial direction of the concavities of the impeller.
In this way, a large opening in the fuel discharge channel can be secured in the circumferential direction. Moreover, the fuel can be discharged smoothly. A fuel pump that exhibits extremely excellent boosting performance can be realized.

Further, the second boundary on the outermost peripheral side of the fuel discharge passage opening of the fuel pump is located at the same position as the outer peripheral end of the impeller recess group or on the outer peripheral side from the outer peripheral end of the impeller recess group. Therefore, it may be located on the inner peripheral side from the outer peripheral surface of the impeller. Further, the most downstream boundary of the opening of the fuel discharge passage on the inner surface of the casing facing the back surface of the impeller (this may be simply referred to as “the downstream end of the opening of the fuel discharge passage” hereinafter). The second groove may be further downstream than the downstream end.
In this way, fuel does not flow from the second groove into the recess of the impeller between the downstream end of the second groove and the downstream end of the opening of the fuel discharge passage. For this reason, the flow of fuel in the recess of the impeller is reduced between the downstream end of the second groove and the downstream end of the opening of the fuel discharge passage. Due to this influence, it has been confirmed that noise during operation of the fuel pump can be reduced. According to the present invention, the operation noise of the fuel pump can be suppressed.

In the above fuel pump, a second boundary of the outermost peripheral side of the opening of the fuel discharge passage, also be formed in an arc shape along a predetermined position which is an inner circumferential side of the outer peripheral surface of the Lee Npera Good.
Since the second boundary is located on the inner peripheral side from the outer peripheral surface of the impeller, it is possible to prevent fuel from entering between the outer peripheral surface of the impeller and the inner surface of the casing facing it. In addition, the second boundary can be widely secured on the outer peripheral side. It has been confirmed that noise during operation of the fuel pump can be reduced by widening the second boundary to the outer peripheral side. According to the configuration of the present invention, it is possible to ensure a large opening of the fuel discharge passage while firmly sealing the opening of the fuel discharge passage.

(Embodiment 1) The most upstream boundary of the opening of the fuel discharge passage on the inner surface of the casing (the second groove (discharge side groove) is formed) facing the back surface of the impeller (this is hereinafter referred to as “fuel discharge passage”) The second groove is partially deeply formed on the upstream side (which may be simply described as “the upstream end of the opening”). This deep groove has the same width as the width of the opening of the fuel discharge passage, and gradually becomes deeper toward the downstream side. The downstream end of the deep groove is continuous with the upstream end of the opening of the fuel discharge channel.
By forming the second groove partly deep and continuing the deeply formed part to the fuel discharge passage, the fuel can be smoothly introduced into the fuel discharge passage.
(Mode 2) The first boundary is adjacent to the second groove over the entire range. That is, the fuel discharge channel opens in the second groove on the inner peripheral side. In this case, the downstream end of the opening of the fuel discharge passage and the downstream end of the second groove are in substantially the same phase.
(Mode 3) The second groove is adjacent to the first boundary in the upstream portion of the opening of the fuel discharge channel. There is no second groove in the range corresponding to the downstream portion of the opening of the fuel discharge passage. In this case, the downstream end of the opening of the fuel discharge channel is located further downstream than the downstream end of the second groove.
(Mode 4) The second boundary may be extended to the outer peripheral side only in the most downstream portion of the opening of the fuel discharge flow path.
Even in this case, it has been confirmed that noise during operation of the fuel pump can be reduced.

First Embodiment An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view of the fuel pump 10. 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) inward. The motor cover 73 is formed with a discharge port 73a that opens upward. Magnets 74 and 75 are fixed to the inner wall of 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 includes an iron core 79 fixed to the shaft 78, a coil (not shown) wound around the iron core 79, and a resin portion 80 that fills the periphery of the coil. 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 attached to the pump cover 14 of the pump portion 12 via a bearing 82.

The pump unit 12 includes a casing 18 and an impeller 20. The impeller 20 has a substantially disk shape. FIG. 2 shows a plan view of the impeller 20. As shown in FIG. 2, a plurality of recess groups 20 a arranged in the circumferential direction are formed on the outer peripheral portion of the impeller 20. In FIG. 2, all the recess groups are not labeled. At the center of the impeller 20, an engagement hole 20c having a substantially D-shaped cross section perpendicular to the axis passing through in the thickness direction is formed.
3 is a cross-sectional view taken along line III-III in FIG. As well shown in FIG. 3, the recesses 20a are formed on both upper and lower (front and back) surfaces of the impeller 20, and the upper and lower recesses 20a are communicated with each other through a communication hole 20b at the bottom. The recess group 20 a is separated from the outer peripheral surface 20 e of the impeller 20 by the outer peripheral wall 20 d of the impeller 20.

The casing 18 is a combination of the pump cover 14 and the pump body 16. As shown in FIG. 1, a circular recess 14 a is formed on the impeller side surface (that is, the lower surface) of the pump cover 14 when viewed in plan. The diameter of the recess 14 a is substantially the same as the diameter of the impeller 20. The recess 14 a has a depth that is substantially the same as the thickness of the impeller 20. The impeller 20 is rotatably fitted in the recess 14a.
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 in a state where the impeller 20 is assembled in the recess 14a of the pump cover 14. 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. Between the lower end of the shaft 78 and the pump body 16, a thrust bearing 33 for receiving the thrust load of the rotor 76 is interposed.

FIG. 4 is a plan view of the pump body 16 viewed from the impeller 20 side (ie, viewed from the upper side of FIG. 1). A substantially C-shaped groove 30 is formed on the surface 16a on the impeller 20 side of the pump body 16 (that is, the upper surface in FIG. 1) when viewed in plan. The groove 30 extends in a region facing the recess group 20 a of the impeller 20. The reference numeral 30 a in FIG. 4 is the upstream end of the groove 30, and the reference numeral 30 b is the downstream end of the groove 30.
The groove 30 is provided with a through hole 32 penetrating the pump body 16 vertically (up and down in FIG. 1). This through-hole 32 functions as vapor removal. The groove 30 is formed with a substantially constant depth from the through hole 32 to the downstream end 30b. The groove 30 gradually becomes deeper from the through hole 32 toward the upstream. The groove 30 communicates with the fuel intake passage 31 in the vicinity of the upstream end 30a. As shown in FIG. 1, the fuel intake passage 31 continues from the groove 30 to the lower surface of the pump body 16 (lower surface in FIG. 1). The fuel intake passage 31 communicates the groove 30 and the outside of the casing 18. As shown in FIG. 4, when the pump body 16 is viewed in plan, it can be seen that a part of the fuel intake passage 31 is open on the upper surface of the pump body 16 (upper surface in FIG. 1). Hereinafter, the groove 30 is referred to as a suction side groove.

  5 is a plan view of the pump cover 14 viewed from the impeller 20 side (ie, viewed from the lower side of FIG. 1) (the impeller 20 is illustrated so that the rotation direction of the impeller 20 is opposite to that of FIG. 4). ). A substantially C-shaped groove 24 is formed on the bottom surface of the recess 14a of the pump cover 14 (hereinafter sometimes referred to as “the bottom surface of the pump cover”) when viewed in plan. The groove 24 extends in a region facing the recess group 20a of the impeller 20 incorporated in the recess 14a. Reference numeral 24 a in FIG. 5 is the upstream end of the groove 24, and reference numeral 24 b is the downstream end of the groove 24. The groove 24 communicates with the fuel discharge passage 26 in the vicinity of the downstream end 24b. The fuel discharge passage 26 continues from the groove 24 to the upper surface of the pump cover 14 (the upper surface in FIG. 1). The fuel discharge channel 26 communicates the groove 24 and the outside of the casing 18. The fuel discharge passage 26 is open on the lower surface of the pump cover 14. Hereinafter, the groove 24 is referred to as a discharge side groove.

The shape of the pump cover 14 will be described in a little more detail. FIG. 6 shows an enlarged view of the vicinity of the fuel discharge passage 26. An opening 27 of the fuel discharge passage 26 (hereinafter simply referred to as “opening 27 of the fuel discharge passage 26”) on the lower surface of the pump cover 14 is formed so as to extend in the circumferential direction along the discharge-side groove 24. Yes. Reference numeral 27 a in the drawing indicates the boundary between the lower surface of the pump cover 14 and the innermost peripheral side of the opening 27. Reference numeral 27 b indicates the lowermost boundary of the pump cover 14 and the outermost boundary of the opening 27. Reference numeral 27 c indicates a boundary between the lower surface of the pump cover 14 and the most upstream side of the opening 27. Reference numeral 27 d indicates the lowermost boundary of the lower surface of the pump cover 14 and the opening 27. Hereinafter, the reference numeral 27a is referred to as "the inner peripheral end of the opening 27 of the fuel discharge passage 26", and the reference numeral 27b is referred to as "the outer peripheral end of the opening 27 of the fuel discharge passage 26", which is indicated by reference numeral 27c. Is referred to as “upstream end of the opening 27 of the fuel discharge passage 26”, and reference numeral 27d is referred to as “downstream end of the opening 27 of the fuel discharge passage 26”.
The inner peripheral end of the discharge side groove 24 is formed so as to be gradually narrowed in the vicinity of the downstream end 24b (shown by the range X). The downstream end 24b of the discharge side groove 24 and the downstream end 27d of the opening 27 of the fuel discharge flow path 26 are located in substantially the same phase.
Reference numeral 130 denotes a part of the groove 24, which gradually becomes deeper as it goes downstream. This portion 130 is deeper than the groove 24 in other portions. The deep groove 130 has the same width as the width of the opening 27 of the fuel discharge passage 26. The downstream end of the deep groove 130 is continuous with the upstream end 27 c of the opening 27 of the fuel discharge passage 26. The groove 130 is provided so that the fuel is smoothly introduced into the fuel discharge passage 26.

7 is a cross-sectional view taken along line VII-VII in FIG. FIG. 7 also shows a cross section of the pump body 16 and the impeller 20. From FIG. 7, it can be clearly seen that the fuel discharge passage 26 is open to the lower surface of the pump cover 14 (in FIG. 7, the opening 27 is indicated by a broken line).
The inner peripheral side surface 26 a and the outer peripheral side surface 26 b of the fuel discharge channel 26 are formed substantially perpendicular to the impeller 20. For this reason, even if the pump cover 14 is viewed in plan from the impeller 20 side, the inner peripheral side surface 26 a and the outer peripheral side surface 26 b of the fuel discharge flow channel 26 cannot be viewed, and the range of the opening 27 of the fuel discharge flow channel 26. Thus, the other side of the pump cover 14 can be visually recognized.
The inner peripheral end of the discharge side groove 24 and the inner peripheral end 100 of the impeller recess 20a are at the same position in the radial direction. The outer peripheral end 27b of the opening 27 of the fuel discharge passage 26 and the outer peripheral end 102 of the impeller recess 20a are at the same position in the radial direction. The inner peripheral end 27a of the opening 27 of the fuel discharge passage 26 is located on the outer peripheral side with respect to the inner peripheral end 100 of the impeller recess 20a. The inner peripheral end 27a is located in the middle of the impeller recess 20a in the radial direction. That is, the width of the fuel discharge passage 26 (the length of the opening 27 in the radial direction) is half of the length of the impeller recess 20a in the radial direction.
A slight gap M is formed between the outer peripheral surface 20e of the impeller 20 and the side surface 14b of the recess 14a of the pump cover 14 (the gap M is slightly exaggerated in FIG. 7). The gap M is provided for the impeller 20 to rotate smoothly.
As can be seen from FIG. 7, the suction side groove 30 is not formed in the pump body 16 at the position of the line VII-VII in FIG. 6 (the shallow suction side groove 30 may be formed). In FIG. 7, a cross section of the pump body 16 further upstream than the line VII-VII in FIG. 6 is indicated by a two-dot chain line. A suction side groove 30 indicated by a two-dot chain line is formed in the pump body 16 on the upstream side of the line VII-VII in FIG.

  As can be seen from FIG. 6, the inner peripheral end 27a of the opening 27 of the fuel discharge passage 26 is formed in an arc shape along an intermediate position in the radial direction of the impeller recess 20a. Further, the outer peripheral end 27b of the opening 27 of the fuel discharge passage 26 is formed in an arc shape along the outer peripheral end 102 of the impeller recess 20a. In this embodiment, by forming the inner peripheral end 27a and the outer peripheral end 27b of the opening 27 of the fuel discharge passage 26 in an arc shape, a large opening 27 of the fuel discharge passage 26 is secured.

When the impeller 20 rotates, a swirl flow that spans the recess 20a on the lower side of the impeller 20 and the suction side groove 30 of the pump body 16 is generated. This swirling flow is indicated by a two-dot chain line arrow D2 'in FIG. The swirl flow D2 ′ enters the inner peripheral side of the impeller recess 20a from the suction side groove 30, flows in the impeller recess 20a from the inner peripheral side to the outer peripheral side along the impeller recess 20a, and the outer peripheral side of the impeller recess 20a. To the suction side groove 30 is formed. The fuel flows along the suction side groove 30 while turning and is pressurized. When the pressure of the fuel is increased along the suction side groove 30, the fuel is sucked from the fuel suction passage 31 of the pump body 16 accordingly. The fuel pressurized in the suction side groove 30 passes through the communication hole 20b (see FIG. 3) of the impeller 20 and merges with the fuel present in the recess 20a on the upper side of the impeller 20. The fuel in the casing 18 is also pressurized along the discharge side groove 24.
A swirling flow is also generated across the recess 20a on the upper side of the impeller 20 and the discharge side groove 24. An arrow D1 in FIG. 7 indicates a swirl flow that straddles the impeller recess 20a and the discharge side groove 24. This swirl flow D1 enters the inner peripheral side of the impeller recess 20a from the discharge side groove 24, flows in the impeller recess 20a along the impeller recess 20a from the inner peripheral side to the outer peripheral side, and the fuel discharge flow path 26 exists. In a range not to be formed, a flow path returning from the outer peripheral side of the impeller recess 20a to the discharge side groove 24 is formed. In the range where the fuel discharge passage 26 exists, the fuel discharged from the outer peripheral side of the impeller recess 20 a flows in the discharge direction along the fuel discharge passage 26.
As indicated by an arrow D2 in FIG. 7, the fuel in the lower impeller recess 20a at the position where the fuel discharge passage 26 is open is formed in the discharge side groove 24 toward the upper impeller recess 20a. It joins with the swirling flow D1.
The fuel whose pressure is increased in the discharge side groove 24 and the fuel whose pressure is increased in the suction side groove 30 joined therewith are sent out into the housing 72 of the motor unit 70 from the fuel discharge passage 26 (see FIG. 6 and the like). 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.

FIG. 14 is an enlarged view of the vicinity of the fuel discharge passage 526 when the pump cover 514 of the conventional fuel pump is viewed in plan. Reference numeral 524 in the figure denotes a discharge side groove. Further, reference numeral 527a indicates an inner peripheral end of the opening 527 of the fuel discharge flow path 526, and reference numeral 527b indicates an outer peripheral end of the opening 527 of the fuel discharge flow path 526.
FIG. 15 shows a cross-sectional view taken along line XV-XV in FIG. An inner peripheral end 527 a of the opening 527 of the fuel discharge flow channel 526 exists at the same position as the inner peripheral end of the recess 20 a of the impeller 20. Further, the outer peripheral end 527 b of the opening 527 of the fuel discharge channel 526 exists at the same position as the outer peripheral end of the recess 20 a of the impeller 20.
In the case of such a conventional configuration, a swirling flow (arrow D1 ′) is generated across the recess 20a on the upper side of the impeller 20 and the fuel discharge passage 526. In this case, due to the influence of the swirl flow D1 ′, a fuel flow (arrow DX) that tends to enter the impeller recess 20a from the fuel discharge passage 526 occurs. That is, a flow that obstructs the flow of fuel in the discharge direction is formed.
According to the fuel pump 10 of the present embodiment, the inner peripheral end 27a of the opening 27 of the fuel discharge passage 26 is formed at an intermediate position in the radial direction of the impeller recess 20a (see FIGS. 6 and 7). Due to such a configuration, it is possible to almost eliminate the phenomenon that the fuel flows in the direction of the impeller recess 20a in the fuel discharge passage 26. In the fuel discharge channel 26, a smooth fuel flow in the discharge direction can be ensured. Thereby, the high-performance fuel pump 10 is realized.

FIG. 8 shows a coordinate plane in which the horizontal axis represents discharge pressure (kPa) and the vertical axis represents efficiency (%). The efficiency here is the product of the discharge pressure and the discharge flow rate divided by the product of the voltage applied to the motor unit 70 and the current consumption. The efficiency is an index indicating the boosting performance of the fuel pump 10. A graph G1 on the coordinate plane shows the relationship between the discharge pressure and the efficiency of the fuel pump 10 of this embodiment when the applied voltage is 12V. The graph G1 ′ shows the relationship between the discharge pressure and the efficiency of the conventional fuel pump (see FIGS. 14 and 15) when the applied voltage is 12V. A graph G2 shows the relationship between the discharge pressure and efficiency of the fuel pump 10 of this embodiment when the applied voltage is 8 V, and a graph G2 ′ shows the discharge pressure and efficiency of the conventional fuel pump when the applied voltage is the same voltage. Showing the relationship. A graph G3 shows the relationship between the discharge pressure and the efficiency of the fuel pump 10 of this embodiment when the applied voltage is 6 V, and a graph G3 ′ shows the discharge pressure and the efficiency of the conventional fuel pump at the same voltage. Showing the relationship.
As can be seen from FIG. 8, the fuel pump 10 of this embodiment shows an efficiency superior to that of the conventional fuel pump. The fuel pump 10 of the present embodiment has a very good boosting performance. It can be understood that the efficiency increase rate compared to the prior art increases as the applied voltage increases.

(Second embodiment)
Here, the description will focus on the differences from the first embodiment. In this embodiment, the shape near the downstream end of the discharge side groove is different from that of the first embodiment. FIG. 9 shows a plan view of the vicinity of the downstream end 224b of the discharge side groove 224 in the present embodiment. In the present embodiment, the downstream end 224 b of the discharge side groove 224 is located far upstream from the downstream end 27 d of the opening 27 of the fuel discharge passage 26. That is, the discharge side groove 224 is not formed along the downstream portion of the fuel discharge passage 26.
10 is a cross-sectional view taken along the line XX of FIG. The inner peripheral end 27a of the opening 27 of the fuel discharge passage 26 is at the intermediate position in the radial direction of the impeller recess 20a, and the outer peripheral end 27b of the opening 27 of the fuel discharge passage 26 is the outer peripheral end of the impeller recess 20a. Is the same as the first embodiment. In the position shown in FIG. 10, the discharge side groove 224 is not formed. In this case, a swirl flow across the impeller recess 20a and the discharge side groove 224 is not generated. Only the flow (arrow D3) from the impeller recess 20a to the fuel discharge passage 26 occurs.
It has been confirmed that the noise generated during operation of the fuel pump 10 can be reduced when configured as in the present embodiment. Even in the configuration of the present embodiment, the pump efficiency is hardly lowered as compared with the first embodiment. Compared with the prior art, high pump efficiency can be exhibited.

(Third embodiment)
Here, the description will focus on the differences from the first embodiment. In this embodiment, the shape of the fuel discharge channel is different from that of the first embodiment. FIG. 11 shows the fuel discharge passage 326 in the present embodiment. Reference numeral 327 in the figure is an opening of the fuel discharge passage 326. Reference numeral 327 a is an inner peripheral end of the opening 327 of the fuel discharge passage 326, and reference numeral 327 b is a downstream end of the opening 327 of the fuel discharge passage 326. In the present embodiment, the outer peripheral end 327b of the opening 327 of the fuel discharge channel 326 is located on the outer peripheral side with respect to the first embodiment. The point that the outer peripheral end 327b of the opening 327 of the fuel discharge flow path 326 is formed in an arc shape is the same as in the first embodiment.
12 is a cross-sectional view taken along line XII-XII in FIG. Similar to the first embodiment, the inner peripheral end 327a of the opening 327 of the fuel discharge passage 326 is located in the middle of the impeller recess 20a in the radial direction. As shown well in FIG. 12, the outer peripheral end 327b of the opening 327 of the fuel discharge passage 326 is located on the outer peripheral side of the outer peripheral end 102 of the impeller recess 20a and on the inner peripheral side of the outer peripheral surface 20e of the impeller 20. is doing. According to the present embodiment, the volume of the fuel discharge channel 326 can be made larger than that in the first embodiment. Since the outer peripheral end 327b of the opening 327 of the fuel discharge passage 326 is located on the inner peripheral side with respect to the outer peripheral surface 20e of the impeller 20, the fuel is placed in the gap M between the outer peripheral surface 20e of the impeller 20 and the side surface 14b of the pump cover 14. Can be prevented from entering.
As in this embodiment, when the fuel discharge channel 326 is expanded to the outer peripheral side (that is, when the outer peripheral side surface 326b of the fuel discharge channel 326 is positioned on the outer peripheral side), the swirling flow indicated by the arrow D4 is outside. A strong collision with the side surface 326b can be prevented. Thereby, it has been confirmed that noise during operation of the pump can be reduced. In this embodiment, it is possible to ensure a large fuel discharge flow path 326 while firmly sealing the fuel discharge flow path 326. Even in the configuration of the present embodiment, high pump efficiency can be exhibited as in the first embodiment.

(Fourth embodiment)
Here, the description will focus on the differences from the first embodiment. In this embodiment, the shape of the fuel discharge channel is different from that of the first embodiment. FIG. 13 shows the opening 427 of the fuel discharge channel 426 in the present embodiment. The fuel discharge channel 426 of this embodiment is bent to the outer peripheral side in the middle (reference numeral 450). And it is extended in the peripheral direction in the downstream from this bending part 450 (code | symbol 452). The outer peripheral end 427b of the fuel discharge channel 426 at the portion indicated by reference numeral 452 is located on the inner peripheral side with respect to the outer peripheral surface 20e of the impeller recess 20a. This prevents the fuel from entering the gap M shown in FIG.
If the fuel discharge channel 426 is bent to the outer peripheral side in the middle, the noise during the pump operation can be reduced in the same manner as the fuel discharge channel is expanded to the outer peripheral side in the third embodiment described above. it can. Even if the configuration of the present embodiment is employed, high pump efficiency can be exhibited as in the first embodiment.

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.
For example, the inner peripheral side surface 26 a and / or the outer peripheral side surface 26 b (see FIG. 7) of the fuel discharge channel 26 may not be perpendicular to the impeller 20. For example, the inner peripheral side surface 26a of the fuel discharge channel 26 may be inclined toward the inner peripheral side. In this way, a large volume of the fuel discharge channel 26 can be secured. Further, for example, even if the outer peripheral side surface 26b of the fuel discharge passage 26 is inclined toward the outer peripheral side, a large volume of the fuel discharge passage 26 can be secured.
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.

It is a longitudinal cross-sectional view of a fuel pump. It is a top view of an impeller. It is the III-III sectional view taken on the line of FIG. It is a top view of a pump body. It is a top view of a pump cover. It is the figure which expanded and showed a part of pump cover. It is the VII-VII sectional view taken on the line of FIG. It is the graph which showed the relationship between discharge pressure and pump efficiency. It is the figure which expanded and showed a part of pump cover (2nd Example). FIG. 10 is a sectional view taken along line XX in FIG. 9. It is the figure which expanded and showed a part of pump cover (3rd Example). It is the XII-XII sectional view taken on the line of FIG. It is the figure which expanded and showed a part of pump cover (4th Example). It is the figure which expanded and showed a part of pump cover of the conventional fuel pump. It is the XV-XV sectional view taken on the line of FIG.

Explanation of symbols

10: pump 12: pump part 14: pump cover, 14a: recess of pump cover, 14b: inner side wall 16: pump body 18: casing 20: impeller, 20a: recess, 20b: communication hole, 20c: engagement hole, 20d: outer peripheral wall, 20e: outer peripheral surface 24: discharge side groove, 24a: upstream end, 24b: downstream end 26: fuel discharge flow path 27: opening of fuel discharge flow path, 27a: inner peripheral end of opening, 27b: opening Outer peripheral end, 27c: upstream end of the opening, 27d: downstream end of the opening 30: suction side groove, 30a: upstream end, 30b: downstream end 31: fuel suction flow path 32: vapor extraction hole 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 , 78b: lower end 79: core, 79a: upper surface 80: resin section 81: Bearing 100: inner peripheral edge of the recess of the impeller 102: outer peripheral edge of the recess of the impeller

Claims (4)

An impeller having a plurality of recess groups formed in an annular shape;
A casing for rotatably accommodating the impeller,
In the “region facing the group of recesses of the impeller” of the casing, a first groove communicating with the fuel intake passage and a second groove communicating with the fuel discharge passage are formed.
The first boundary on the innermost peripheral side of the opening of the fuel discharge flow path is at a substantially intermediate position in the radial direction of the recess group of the impeller,
Second boundary of outermost peripheral side of the opening of the fuel discharge passage, an outer peripheral edge by Ri outer peripheral side of the recess group impeller located on the inner peripheral side from the outer peripheral surface of the impeller,
A fuel pump, wherein a side surface on the inner peripheral side of the fuel discharge channel extends from the first boundary perpendicularly to the back surface of the impeller or inclined toward the inner peripheral side. An impeller having a plurality of recess groups formed in an annular shape;
A casing for rotatably accommodating the impeller,
In the “region facing the group of recesses of the impeller” of the casing, a first groove communicating with the fuel intake passage and a second groove communicating with the fuel discharge passage are formed.
The first boundary on the innermost peripheral side of the opening of the fuel discharge flow path is at a substantially intermediate position in the radial direction of the recess group of the impeller,
The second boundary on the outermost peripheral side of the opening of the fuel discharge channel is at the same position as the outer peripheral end of the recess group of the impeller, or on the outer peripheral side from the outer peripheral end and on the inner peripheral side from the outer peripheral surface of the impeller. Yes,
An inner peripheral side surface of the fuel discharge channel extends from the first boundary perpendicularly to the back surface of the impeller or inclined toward the inner peripheral side,
A fuel pump, wherein the most downstream boundary of the opening of the fuel discharge channel is further downstream than the downstream end of the second groove.   3. The fuel pump according to claim 1, wherein the first boundary is formed in an arc shape along a substantially intermediate position in the radial direction of the recess group of the impeller.   4. The fuel pump according to claim 1, wherein the second boundary is formed in an arc shape along a predetermined position that is on the inner peripheral side from the outer peripheral surface of the impeller. 5.

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