JP2010144609A - Fuel pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel pump preventing an impeller from contacting foreign matter accumulated near the outer periphery of the impeller and preventing degradation of pumping efficiency. <P>SOLUTION: In the fuel pump including the impeller 20 having a substantially disc-like shape rotated by a motor part 70, and a casing 18 for rotatably housing the impeller 20, foreign matter escape passages 100, 101 are formed on an inner face of the casing opposing the impeller 20 at a position opposing a region sandwiched by the outer periphery of the impeller 20, and a first blade groove group 20b and a second blade groove group 20c, and on the circumference excluding a portion from a fuel discharge port 41 to a fuel suction port 40 viewed from the rotating direction of the impeller 20, for discharging foreign matter mixed in fuel sucked from the fuel suction port 40 into the casing 18, to the fuel discharge port 41. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a fuel pump having an impeller and a casing that rotatably accommodates the impeller.

A fuel pump is known as a device for supplying fuel in a fuel tank to an internal combustion engine (for example, an automobile engine or the like). In this type of fuel pump, the pump unit includes a casing and a substantially disk-shaped impeller that is rotatably accommodated in the casing. On the suction side of the impeller, a blade groove is formed in an annular shape along the outer periphery of the impeller. On the discharge side surface of the impeller, a blade groove portion is formed at a position corresponding to the blade groove portion formed on the suction side. The blade groove portions formed on the suction side surface and the discharge side surface of the impeller communicate with each other at the bottom portion.
Each of the inner surface of the casing facing the intake side and the discharge side of the impeller is formed with a pump passage extending from the upstream end to the downstream end along the rotation direction of the impeller in a region facing the blade groove formed in the impeller. Yes. The upstream end of the suction-side pump passage communicates with the outside of the casing through a fuel suction port, and the downstream end of the discharge-side pump passage communicates with the outside of the casing through a fuel discharge port.

In this fuel pump, when the impeller rotates, fuel is sucked into the casing from the suction port, and the sucked fuel is introduced into the blade groove portion of the impeller and the pump passage. Centrifugal force due to the rotation of the impeller acts on the fuel sucked into the casing. The fuel sucked into the casing flows downstream along the pump passage while being pressurized by the centrifugal force of the impeller, and is discharged out of the casing from the discharge port.
In many cases, foreign matter (solid) is mixed in the fuel sucked by the fuel pump. When the fuel sucked into the casing is agitated by the rotation of the impeller, the foreign matter having a mass larger than that of the fuel is separated from the fuel by the centrifugal force of the impeller and accumulates on the inner surface of the casing near the outer periphery of the impeller. Usually, the distance between the impeller and the inner surface of the casing is about several μm to several tens of μm in consideration of pump efficiency. Therefore, if foreign matter accumulates on the inner surface of the casing, the accumulated foreign matter may come into contact with the impeller. When the impeller comes into contact with the accumulated foreign matter, the impeller and / or the inner surface of the casing is worn to cause fuel leakage from the pump passage, resulting in a decrease in pump efficiency.
Therefore, a recess is formed at a position outside the outer periphery of the impeller on the inner surface of the casing facing the impeller surface. In this fuel pump, the foreign matter agitated by the impeller and separated from the fuel is accumulated in a recess formed on the inner surface of the casing. Therefore, contact between the impeller and the foreign matter is suppressed, and impeller wear is suppressed. As a result, the pump efficiency can be kept high. As a conventional example of this type of fuel pump, for example, Patent Document 1 is cited.

JP 2008-51020 A

  In the fuel pump disclosed in Patent Document 1, when a large amount of foreign matter is sucked into the pump, the foreign matter exceeds the allowable accumulation amount of the recess, overflows from the recess inlet, and starts to accumulate on the inner surface of the casing near the outer periphery of the impeller. Then, the impeller starts to come into contact with foreign matter, impeller wear occurs, and pump efficiency begins to decrease. A similar phenomenon occurs when a small amount of foreign matter is inhaled over a long period of time.

  The present invention has been made in order to solve the above-described problems, and the object thereof is to prevent contact between the impeller and foreign matter accumulated in the vicinity of the outer periphery of the impeller, thereby preventing reduction in pump efficiency. It is to provide a fuel pump.

  A fuel pump according to the present invention includes a substantially disk-shaped impeller rotated by a motor unit, and a casing that rotatably accommodates the impeller, and a front surface and a rear surface of the impeller are spaced apart from each other by a predetermined distance from the outer periphery. In the region extending in the circumferential direction, a first blade groove group and a second blade groove group consisting of recess groups continuous in the circumferential direction are formed, respectively, and the first blades are formed on the casing inner surface facing the impeller surface. A first pump passage extending from an upstream end to a downstream end in a region facing the groove group is formed, and a region facing the second blade groove group is formed from the upstream end on the casing inner surface facing the impeller back surface. A second pump passage extending to the downstream end is formed, and the casing has a fuel inlet that communicates the vicinity of the upstream end of the first pump passage and the outside of the casing, and the second pump In the fuel pump in which a fuel discharge port that communicates between the vicinity of the downstream end of the passage and the outside of the casing is formed, the outer periphery of the impeller, the first blade groove group, and the second blade are formed on the inner surface of the casing facing the impeller. At a position facing a region sandwiched by the groove group and on a circumference excluding a portion from the fuel discharge port to the fuel intake port as viewed in the rotation direction of the impeller, from the fuel intake port to the A foreign matter escape passage is formed to discharge foreign matter mixed in the fuel sucked into the casing to the fuel discharge port.

  According to the fuel pump of the present invention, the foreign matter stirred from the impeller and separated from the fuel is discharged from the foreign matter escape passage formed on the inner surface of the casing to the outside of the pump, so that the foreign matter is not accumulated inside the pump. The contact between the impeller and the foreign matter is suppressed, and the wear of the impeller is suppressed, whereby the pump efficiency can be maintained high.

Embodiment 1 FIG.
A first embodiment according to the present invention will be described with reference to the drawings.
First, the mechanical configuration of the fuel pump will be described with reference to FIG. 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, and a rotor 76. 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 has a main body 77 (configured by a laminated iron core and a coil) and a shaft 78 that penetrates the main body 77 up and down. An upper end portion 78 a of the shaft 78 is rotatably attached to the motor cover 73 via a bearing 79. A lower end 78 b of the shaft 78 is rotatably mounted on the pump cover 14 of the pump unit 12 via a bearing 79. Since the motor unit 70 has the same configuration as that of a conventional fuel pump, further detailed description thereof is omitted.

FIG. 2 shows an enlarged view of the pump unit 12 shown in FIG. The pump unit 12 includes a casing 18 and an impeller 20.
As shown in FIG. 3, the impeller 20 has a substantially disk shape. On the suction side surface of the impeller 20, a first blade groove group 20 b made of a group of recesses continuous in the circumferential direction is formed annularly at a predetermined distance from the outer peripheral surface 20 e. That is, the first blade groove group 20 b 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 discharge side surface of the impeller 20 has a recess that is continuous in the circumferential direction at a position corresponding to the first blade groove group 20b formed on the suction side surface of the impeller 20 (that is, a region separated from the outer peripheral surface 20e by a predetermined distance). A second blade groove group 20c consisting of a group is formed in an annular shape. In addition, the bottom part of the 1st blade groove group 20b and the bottom part of the 2nd blade groove group 20c are connected by the communication hole (illustration omitted). At the center of the impeller 20, an engagement hole 20a having a substantially D-shaped cross section perpendicular to the axis passing through in the thickness direction is formed. A shaft 78 is engaged with the engagement hole 20a. When the coil of the rotor 77 is energized, the shaft 78 rotates and thereby the impeller 20 rotates.

  The casing 18 is a combination of the pump cover 14 and the pump body 16. As shown in FIGS. 2 and 5, the impeller side surface of the pump cover 14 (that is, the lower surface in FIG. 1) is formed with a circular recess 14 a in plan view. The diameter of the recess 14 a is substantially the same as the diameter of the impeller 20, and the depth of the recess 14 a is substantially the same as the thickness of the impeller 20. The impeller 20 is rotatably fitted in the recess 14a.

  On the bottom surface of the recess 14a of the pump cover 14 (hereinafter sometimes referred to as the “lower surface of the pump cover 14”), a groove-shaped second pump extending in the circumferential direction in a region facing the second blade groove group 20c of the impeller 20 A passage 31 is formed. The upstream end 31a of the second pump passage 31 is formed in the vicinity of a position facing an upstream end 30a of the first pump passage 30 described later. A fuel discharge port 41 is formed at the downstream end 31 b of the second pump passage 31. The fuel discharge port 41 extends from the second pump passage 31 to the upper surface of the pump cover 14 (upper surface in FIG. 1), and connects the second pump passage 31 and the outside of the casing 18 (that is, the pump portion 70 in the housing 72). Communicate.

  A slight axial gap shown in FIG. 6A is formed between the impeller 20 and the concave portion 14a of the pump cover 14, and between the impeller 20 and the inner peripheral surface 14b of the concave portion 14a of the pump cover 14. In FIG. 6, a slight gap indicated by B in FIG. 6 is formed. These gaps are provided for the impeller 20 to rotate smoothly.

Further, as shown in FIGS. 2 and 5, a circular concave portion 14 c is formed on the surface of the pump cover 14 facing the impeller 20, that is, the bottom surface of the concave portion 14 a when viewed in plan. The diameter of the recess 14 c is smaller than the diameter of the impeller 20. The depth of the recess 14c is extremely smaller than the thickness of the impeller 20, gradually increases from the outer peripheral side toward the center, and is about a dozen μm at the inner peripheral portion of the recess 14c. Therefore, the lower surface of the pump cover 14 has a concave shape on the lower side.
In the figure, the gap between the impeller 20 and the pump cover 14 is schematically shown broadly, but in actuality, it is about several μm to several tens of μm.

  The recess 14a of the pump cover 14 has a second pump passage 31 at a position facing the outer peripheral wall sandwiched between the outer peripheral surface 20e of the impeller 20 and the second blade groove group 20c and in the impeller rotation direction P. On the circumference excluding the portion from the downstream end 31b to the upstream end 31a, a foreign substance escape passage 100 having an enlarged clearance is formed.

The depth of the foreign substance escape passage 100 is larger than the axial gap A of the impeller 20 and the recess 14a of the pump cover 14, and is formed by the outer peripheral surface 20e of the impeller 20 and the inner peripheral surface 14b of the recess 14a of the pump cover 14. Is equal to or less than the radial gap B (see FIG. 6).
The width of the foreign substance escape passage 100 in the radial direction is gradually narrowed toward the second pump passage 31 in the vicinity of the downstream end 31b of the second pump passage 31 (see FIG. 5).
Further, the outer peripheral side corner portion 100a of the foreign object escape passage 100 is chamfered or rounded as shown in FIG.

As shown in FIGS. 2 and 4, the impeller 20 side surface of the pump body 16 (that is, the upper surface in FIG. 1) is formed with a circular recess 16 a in plan view. The diameter of the recess 16 a is smaller than the diameter of the impeller 20. The depth of the recess 16a is extremely small compared to the thickness of the impeller 20, gradually increases from the outer peripheral side toward the center, and is about several μm at the inner periphery of the recess 16a. Therefore, the upper surface of the pump body 16 has a concave shape on the upper side.

  On the upper surface of the pump body 16, a groove-shaped first pump passage 30 extending in the circumferential direction in a region facing the first blade groove group 20 b of the impeller 20 is formed. A fuel inlet 40 is provided at the upstream end 30 a of the first pump passage 30. Between the upstream end 30a and the downstream end 30b of the first pump passage 30, there is provided a vapor removal hole 30c penetrating the pump body 16 up and down (up and down in FIG. 1). A recess 16b is formed at the center of the upper surface 16a of the pump body 16, and a thrust bearing 33 is disposed concentrically with the shaft 78 in the recess 16b. The thrust bearing 33 receives the thrust load of the rotor 76.

  On the outer peripheral side of the first pump passage 30 of the pump body 16, at a position facing the outer peripheral wall 20 d sandwiched between the outer peripheral surface 20 e of the impeller 20 and the first blade groove group 20 b and in the impeller rotation direction P On the circumference excluding the portion sandwiched between the downstream end 30b and the upstream end 30a of the first pump passage 30, a foreign substance escape passage 101 with an enlarged clearance is formed. The outer diameter of the foreign substance escape passage 101 is matched with the inner peripheral surface 14b of the recess 14a of the pump cover 14.

The depth of the foreign substance escape passage 101 is larger than the axial gap A of the impeller 20 and the concave portion 14a of the pump cover 14, and is formed by the outer peripheral surface 20e of the impeller 20 and the inner peripheral surface 14b of the concave portion 14a of the pump cover 14. Is equal to or less than the radial gap B (see FIG. 6).
The width of the foreign substance escape passage 101 in the radial direction is gradually narrowed toward the first pump passage 30 in the vicinity of the downstream end 30b of the first pump passage 30 (see FIG. 4).
Furthermore, the outer peripheral side corner portion 101a of the foreign substance escape passage 101 is chamfered or rounded as shown in FIG.

The casing 18 (including the pump cover 14 and the pump body 16) is fixed to the housing 72 by caulking the lower end 72b of the housing 72 inward with the impeller 20 assembled in the recess 14a of the pump cover 14.
In a state where the casing 18 is fixed to the housing 72, the lower end portion 78 b of the shaft 78 is fitted into the engagement hole 20 a of the impeller 20 at a portion further below the portion supported by the bearing 79. . A thrust bearing 33 is interposed between the lower end of the shaft 78 and the pump body 16 (see FIG. 1).

  In the fuel pump 10 described above, when current flows through the rotor 76 and the impeller 20 rotates, the fuel in the fuel tank (not shown) is sucked into the casing 18 through the fuel inlet 40. The fuel sucked into the casing 18 first flows into the upstream end 30 a of the first pump passage 30. As shown in FIG. 6, the fuel that has flowed into the first pump passage 30 forms a swirl flow S between the first pump passage 30 and the first blade groove group 20b by the rotation of the impeller 20, and is boosted thereby. The The fuel that has flowed into the first pump passage 30 flows through the first pump passage 30 from the upstream end 30a toward the downstream end 30b while being pressurized by the rotation of the impeller. For this reason, foreign matter mixed in the fuel (having a larger specific gravity than the fuel) is separated to the outside in the radial direction of the impeller by centrifugal force.

  The separated foreign matter is pushed out into the swirling flow S, flows into the foreign matter escape passage 101 formed in the pump body 16, passes through the foreign matter escape passage 101, and flows into the downstream end 30 b of the first pump passage 30. . The foreign matter flows through the gap B between the recess 14 a of the pump cover 14 and the outer peripheral surface 20 e of the impeller 20 and flows from the fuel discharge port 41 at the downstream end 31 b of the second pump passage 31 of the pump cover 14 to the motor unit 70. Discharged.

  Since the depth of the foreign substance escape passage 101 is larger than the axial gap A between the impeller 20 and the recess 14 a of the pump cover 14, the foreign substance selectively flows into the foreign substance escape passage 101 instead of the axial gap A. Further, since the depth of the foreign substance escape passage 101 is equal to or less than the radial gap B formed by the concave portion 14a of the pump cover 14 and the outer peripheral surface 20e of the impeller 20, the fuel from the radial gap B is reduced. While the pressure drop due to leakage is suppressed, the foreign matter smoothly passes through the radial gap B and is guided to the fuel discharge port 41.

  On the other hand, the foreign matter that has passed through the communication hole (not shown) from the first blade groove group 20b to the second blade groove group 20c of the impeller 20 and has flowed into the second pump passage 31 of the pump cover 14 is also the same. The impeller is separated radially outward by the centrifugal force of rotation. The separated foreign matter flows into the foreign matter escape passage 100 formed in the pump cover 14, passes through the foreign matter escape passage 100, and from the fuel discharge port 41 at the downstream end 31 b of the second pump passage 31 to the motor unit 70. Is discharged.

  The width of the foreign object escape passage 100 in the radial direction is gradually narrowed toward the second pump passage 31 in the vicinity of the downstream end 31 b of the second pump passage 31, so that the foreign matter extends along the outer peripheral surface of the foreign matter escape passage 100. It is smoothly guided to the fuel discharge port 41. Further, since the outer peripheral side corner portion 100a of the foreign substance escape passage 100 is chamfered or rounded, there is no portion where the flow velocity becomes slow in the cross section of the passage, and foreign matter does not accumulate in the passage. These effects are the same in the foreign substance escape passage 101.

  Since the foreign object escape passages 100 and 101 are formed outside the outer periphery of the impeller 20, the impeller 20 does not contact the foreign matter flowing on the outer peripheral side in the foreign matter escape passages 100 and 101 while receiving centrifugal force. Therefore, since the impeller 20 can rotate without coming into contact with foreign matter, the rotational resistance can be kept low, and the impeller 20 can rotate smoothly.

  The fuel discharged to the motor unit 70 from the fuel discharge port 41 formed at the downstream end of the second pump passage 31 flows through the motor unit 70 and out of the fuel pump 10 from the discharge port 73a formed in the motor cover 73. And discharged.

In the fuel pump 10 described above, the foreign matter escape passages 100 and 101 are formed on the inner surface of the casing 18 so that the foreign matter in the fuel is separated from the first pump passage 30 and the second pump passage 31 and the impeller caused by the foreign matter in the fuel. 20 and / or wear of the inner surface of the casing 18 is suppressed. As a result, fuel leakage from the first pump passage 30 and the second pump passage 31 is prevented, and the pump efficiency of the fuel pump 10 can be maintained over a long period of time.
Further, in the fuel pump 10 described above, since the fuel escape groove is formed only in the pump body 16 and the pump cover 14, conventional configurations (parts) can be used for other portions.
Further, since the upper surface 16a of the pump body 16 is concave, the impeller 20 can be prevented from tilting while the impeller 20 is rotating.

  In the above-described embodiment, the foreign substance escape passages 100 and 101 formed on the inner surface of the casing 18 are formed in each of the pump body 16 and the pump cover 14, but can be formed only in one of them.

  It should be noted that various modifications or changes of the present invention can be realized without departing from the scope and spirit of the present invention by a related skilled engineer, and are not limited to the embodiments described in this specification. Should be understood.

It is a longitudinal cross-sectional view which shows the fuel pump which concerns on Embodiment 1 of this invention. It is a principal part longitudinal cross-sectional view which expands and shows the pump part in FIG. It is a top view which shows the impeller in FIG. It is the top view which looked at the pump body from the impeller side in FIG. It is the top view which looked at the pump cover from the impeller side in FIG. FIG. 3 is an enlarged longitudinal sectional view of a main part showing the vicinity of a foreign substance escape passage in FIG. 2.

Explanation of symbols

10: Fuel pump
12: Pump part
14: pump cover, 14a: recess, 14b: inner peripheral surface, 14c: recess 16: pump body, 16a: recess, 16b: recess 18: casing
20: impeller, 20a: engagement hole, 20b: first blade groove group, 20c: second blade groove group 20d: outer peripheral wall, 20e: outer peripheral surface 30: first pump passage, 30a: upstream end, 30b: downstream end 30c: Vapor vent hole 31: Second pump passage, 31a: Upstream end, 31b: Downstream end 33: Thrust bearing 40: Fuel inlet 41: Fuel outlet 70: Motor part
72: Housing
73: Motor cover 74, 75: Magnet
76: Rotor
77: body 78: shaft, 78a: upper end portion, 78b: lower end portion 79: bearing 100: foreign object escape passage, 100a: outer peripheral side corner portion 101: foreign matter escape passage, 101a: outer peripheral side corner portion

Claims (6)

A substantially disk-shaped impeller rotated by a motor unit, and a casing that rotatably accommodates the impeller,
On the front and back surfaces of the impeller, a first blade groove group and a second blade groove group each formed of a group of recesses continuous in the circumferential direction are formed in regions extending in the circumferential direction with a predetermined distance from the outer periphery to the inside. ,
A first pump passage extending from an upstream end to a downstream end in a region facing the first blade groove group is formed on the casing inner surface facing the impeller surface,
A second pump passage extending from an upstream end to a downstream end in a region facing the second blade groove group is formed on the casing inner surface facing the impeller back surface,
The casing includes a fuel suction port that communicates between the vicinity of the upstream end of the first pump passage and the outside of the casing, and a fuel discharge port that communicates between the vicinity of the downstream end of the second pump passage and the exterior of the casing. In the fuel pump formed with
The fuel is seen from the inner surface of the casing facing the impeller at a position facing a region sandwiched between the outer periphery of the impeller and the first blade groove group and the second blade groove group and when viewed in the rotation direction of the impeller. A foreign material escape passage is formed on the circumference excluding the portion from the discharge port to the fuel suction port to discharge foreign matter mixed in the fuel sucked into the casing from the fuel suction port into the fuel discharge port. A fuel pump characterized by that.   2. The depth of the foreign substance escape passage is larger than an axial gap between the impeller and the casing and equal to or less than a radial gap between the impeller and the casing. The fuel pump described.   The fuel pump according to claim 1 or 2, wherein a width of the foreign substance escape passage in a radial direction is gradually narrowed in the vicinity of the fuel discharge port.   4. The fuel pump according to claim 1, wherein an outer peripheral side corner portion of the foreign object escape passage is chamfered or rounded. 5.   The casing includes a pump body having the fuel suction port and a pump cover having the fuel discharge port, and a circular shape having a depth substantially equal to the thickness of the impeller on a surface of the pump cover on the impeller side. The fuel pump according to any one of claims 1 to 4, wherein a recess is formed.   A circular recess having a depth smaller than the diameter of the impeller and smaller than the thickness of the impeller and gradually increasing from the outer peripheral side toward the center is formed on the bottom surface of the recess. The fuel pump according to claim 5.

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