JPWO2013054412A1 - Fuel pump - Google Patents

Abstract

For the purpose of obtaining a fuel pump that has a simple and inexpensive configuration, prevents the occurrence of problems such as an increase in rotational resistance of the impeller and locks in the pump chamber, and ensures both reliability and maintenance of the pump performance. At least one seal portion of the casing (18) facing the impeller recesses (20b, 20c) at a position on the order of micron-order, with the amount of swelling of the recesses (20b, 20c) of the impeller (20) predicted. The shape (35, 36) is formed, or the shape of the recess group (20b, 20c) of the impeller (20) is defined as a concave shape (50a, 50b) in which the amount of expansion of the recess group of the impeller is predicted. did.

Description

  The present invention relates to a fuel pump, and more particularly, to a fuel pump having an impeller and a pump 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). This type of fuel pump usually has a pump portion. The pump unit includes a casing and a substantially disk-shaped impeller that is rotatably accommodated in the casing. A blade groove portion is formed in an annular shape along the outer peripheral portion of the impeller on the surface of the impeller facing the fuel suction side. A blade groove portion is formed on the surface of the impeller facing the fuel discharge side 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 the fuel pump configured as described above, when the impeller rotates, fuel is sucked into the pump casing from the suction port, and the sucked fuel is introduced into the impeller blade groove and the pump passage. Centrifugal force due to the rotation of the impeller acts on the fuel sucked into the pump casing. The fuel sucked into the pump casing flows downstream along the pump passage while being pressurized by the centrifugal force of the impeller, and is discharged out of the pump casing from the discharge port.
In such a fuel pump, in order to prevent reduction in pump discharge efficiency due to leakage loss, which occurs in the gap between the impeller surface and the pump cover and pump base sliding surface in contact with the impeller surface, the thrust direction The gap is very small. For this reason, when the fuel pressure in the pump chamber rises from the fuel intake port toward the pump chamber outlet due to the rotation of the blade groove, the impeller is pressure between the pump chamber outlet in the pump casing and the fuel inlet in the pump casing. Due to the imbalance, the pump casing rotates while contacting a position facing the pump chamber outlet.
Therefore, in order to prevent this contact, a gap larger than a minute gap between the surface of the impeller and the pump casing may be formed in the vicinity of the pump outlet on the sliding surface of the pump casing to form a contact relief portion. Are known. (For example, refer to Patent Document 1.)

JP-A-5-187382

  Through experiments and verifications by the inventor, it was confirmed that the dimensional deformation of the impeller appears remarkably in the recess group. Therefore, in order to prevent the contact between the pump casing and the impeller, it has been difficult to say that the contact relief portion shown in Patent Document 1 alone is perfect.

  The present invention has been made in view of the above-described circumstances, and has a simple and inexpensive configuration, prevents the occurrence of problems such as an increase in the rotational resistance of the impeller and the lock of the pump chamber, and ensures reliability and pump performance. It aims at providing the fuel pump which made maintenance compatible.

  A fuel pump according to the present invention is a fuel pump comprising a disk-shaped impeller, a casing including a pump cover and a pump body that rotatably accommodates the impeller, and a motor unit that rotationally drives the impeller. Each of the front and back surfaces of the impeller is formed with a group of recesses that repeat in the circumferential direction in a region extending in the circumferential direction at a predetermined distance from the outer periphery to the inner side, and the pump cover facing the impeller surface has an impeller A first groove extending from the upstream end to the downstream end is formed in a region facing the recess group of the pump, and the pump body facing the impeller back surface has a region facing the recess group of the impeller downstream from the upstream end. A second groove extending to the end is formed, the casing includes a fuel discharge port that communicates the vicinity of the downstream end of the first groove and the outside of the casing, and an upstream end of the second groove A fuel suction port communicating with the outside of the casing is formed between the upstream end and the downstream end of the first groove of the pump cover and the upstream end and the downstream of the pump body as viewed in the rotation direction of the impeller. In the fuel pump in which a seal portion is provided between the ends, the swelling amount of the recess group of the impeller is predicted at a position facing the recess group of the impeller of at least one seal portion of the casing. A concave shape of micron order is formed.

  According to the fuel pump of the present invention, with a simple and inexpensive configuration, it is possible to prevent the occurrence of problems such as an increase in the rotational resistance of the impeller and the lock of the pump chamber, thereby ensuring both reliability and maintaining pump performance. A fuel pump can be obtained.

  The above-described and other objects, features, and effects of the present invention will become more apparent from the detailed description and the drawings in the following embodiments.

1 is a longitudinal sectional view showing the overall configuration of a fuel pump according to Embodiment 1 of the present invention. FIG. 2 is an enlarged longitudinal sectional view of a pump part in FIG. 1 is a plan view of an impeller according to Embodiment 1 of the present invention. FIG. 3 is a plan view of the pump body according to the first embodiment of the present invention as viewed from the impeller side. FIG. 3 is a plan view of the pump cover according to the first embodiment of the present invention viewed from the impeller side. It is a fragmentary sectional view of pump part 12 in Embodiment 1 of this invention.

Embodiment 1 FIG.
Embodiment 1 of the present invention will be described with reference to FIGS.
In addition, in each figure, the same code | symbol shall show the same or an equivalent part.

To summarize the features of the present invention, a clearance is further provided in the seal portion from the fuel discharge port to the fuel intake port as viewed in the impeller rotation direction on the sliding surface of the casing inner surface facing the impeller blade groove group. A concave shape on a substantially circumference enlarged in a micron order is formed.
FIG. 1 is a longitudinal sectional view showing the overall configuration of the fuel pump according to the first embodiment of the present invention. 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 composed of a laminated iron core and coils, 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 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. Here, since the motor unit 70 has the same configuration as that of the conventional fuel pump, further detailed description thereof is omitted.

FIG. 2 shows an enlarged view of the pump portion of 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 surface of the impeller 20 on the fuel suction side, a first blade groove group 20b that is continuous in the circumferential direction is formed in an annular shape with a predetermined distance from the outer peripheral surface 20e. 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 surface on the fuel discharge side of the impeller 20 is circumferentially positioned 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 continuous second blade groove group 20c 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), a groove-shaped second pump passage 31 extending in the circumferential direction in a region facing the second blade groove group 20c of the impeller 20 is provided. 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 communicates the second pump passage 31 with the outside of the casing 18 (specifically, inside the housing 72). ing.

A slight axial gap A shown in FIG. 6 is formed between the impeller 20 and the recess 14 a of the pump cover 14, and between the impeller 20 and the inner peripheral surface 14 b of the recess 14 a of the pump cover 14. Is formed with a slight radial gap B shown in FIG. These gaps A and B are provided for the impeller 20 to rotate smoothly.
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.

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 in the central portion 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.

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 inserted into the engagement hole 20 a of the impeller 20 at a portion further below the portion supported by the bearing 82. . A thrust bearing 33 is interposed between the lower end of the shaft 78 and the pump body 16.

  In the fuel pump 10 configured as 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 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. The fuel discharged from the fuel discharge port 41 formed at the downstream end of the second pump passage 31 to the motor unit 70 flows through the motor unit 70 and is discharged from the discharge port 73a formed in the motor cover 73 to the fuel pump 10. It is discharged outside.

The slight gap A in the axial direction shown in FIG. 6 is one of the factors that greatly influence the discharge performance of the fuel pump 10. That is, if the clearance is widened, the smooth flow of the swirl flow S is hindered, and at the same time, the leakage loss in the casing 18 increases, resulting in a decrease in the amount of fuel discharged from the fuel discharge port 41. cause. That is, maintaining and managing the clearance as small as possible is an extremely important issue in maintaining the discharge performance of the pump. On the other hand, the impeller 20 is formed of a thermosetting or thermoplastic resin material. As described above, since the impeller 20 is usually used in a state of being always immersed in fuel, a dimensional change (swelling) due to moisture absorption. Is known to happen.
When the amount of swelling due to moisture absorption approaches the clearance A provided in the axial direction, the rotational motion is hindered by interference between the impeller and the casing, thereby increasing the rotational wear resistance and causing the fuel pump discharge efficiency to decrease. When the impeller 20 swells beyond the set clearance A, there is a concern that the pump chamber may be locked in the worst case. From the above background, it is necessary to set and manage the clearance as small as possible without causing a lock or the like in consideration of swelling of the impeller due to fuel immersion.

In the form having the outer ring portion 20g shown in FIG. 3, particularly in the thermosetting resin impeller 20, the amount of swelling in the blade portion 20f is large compared to other portions (planar portion, outer peripheral portion 20e). Have. In the first embodiment, paying attention to the above features, a concave shape that anticipates the amount of swelling is provided in advance in the portion of the casing 18 facing the impeller blade portion 20f on the sliding surface.
Specifically, with respect to the pump passages 30 and 31 on the substantially C-shape provided on the sliding surfaces of the pump body 16 and the pump cover 14, in other words, along the direction of extending them in the circumferential direction. For example, the concave portions 35 and 36 on the order of microns that allow the impeller 20 to swell are formed in the seal portions provided between the upstream end 30a and the downstream end 30b of the pump passages 30 and 31, and between the upstream end 31a and the downstream end 31b. Establishing partial clearance expansion.

  According to the fuel pump of the first embodiment of the present invention configured as described above, even when the blade portion 20f swells, the occurrence of problems such as an increase in rotational resistance of the impeller 20 or a pump chamber lock is prevented. Can do. At the same time, since the area where the clearance is enlarged is limited to only the necessary area, the pump discharge performance is not greatly reduced, that is, the reliability can be ensured and the pump performance can be maintained.

  In the above description, the concave shapes 35 and 36 formed on the inner surface of the casing 18 have been described as being formed on each of the pump body 16 and the pump cover 14, but can be formed only on one of them. .

  In contrast to the above-described embodiment, as shown in FIG. 6, the same effect can be expected even if concave shapes 50a and 50b that allow for the swelling amount are provided on the impeller side.

  Further, in the fuel pump 10 of the above-described first embodiment, the concave shape is formed only in the pump body 16 and the pump cover 14 or the impeller 20, so that the other parts use conventional configurations (parts). It is something that can be done.

As mentioned above, although the specific example of this invention was demonstrated in detail using Embodiment 1, these are only illustrations and do not limit a claim. 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 the 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 exemplified in this specification or the drawings achieves a plurality of objects at the same time, and has technical utility by achieving one of the objects.

  The present invention is suitable as a fuel pump for supplying fuel in a fuel tank to an internal combustion engine (for example, an automobile engine or the like).

10: Fuel pump, 12: Pump part, 14: Pump cover, 16: Pump body,
18: casing, 20: impeller,
20b: first blade groove group (recess group),
20c: second blade groove group (recess group), 30, 31: pump passage,
30a: upstream end of the pump passage 30; 30b: downstream end of the pump passage 30;
31a: the upstream end of the pump passage 31, 31b: the downstream end of the pump passage 31,
35: concave shape (pump body side), 36: concave shape (pump cover side),
40: fuel inlet, 41: fuel outlet,
50a, 50b: concave shape (impeller side),
70: motor part, 72: housing, 73: motor cover,
74, 75: Magnet,
76: Rotor, 78: Shaft.

A fuel pump according to the present invention is a fuel pump comprising a disk-shaped impeller, a casing including a pump cover and a pump body that rotatably accommodates the impeller, and a motor unit that rotationally drives the impeller. Each of the front and back surfaces of the impeller is formed with a group of recesses that repeat in the circumferential direction in a region extending in the circumferential direction at a predetermined distance from the outer periphery to the inner side, and the pump cover facing the impeller surface has an impeller A first groove extending from the upstream end to the downstream end is formed in a region facing the recess group of the pump, and the pump body facing the impeller back surface has a region facing the recess group of the impeller downstream from the upstream end. A second groove extending to the end is formed, the casing includes a fuel discharge port that communicates the vicinity of the downstream end of the first groove and the outside of the casing, and an upstream end of the second groove A fuel suction port communicating with the neighbor and the casing outside is formed, as viewed in the impeller rotational direction, between the upstream and downstream ends of the first groove of the pump cover, and upstream of the second groove of the pump body In the fuel pump in which a seal portion is provided between the end and the downstream end, the amount of swelling of the recess group of the impeller at a position facing the recess group of the impeller of at least one seal portion of the casing A concave shape having a micron order is predicted, and an increase in rotational resistance of the impeller is prevented even when the concave group of the impeller swells .

Claims (4)

A disk-shaped impeller (20), a casing (18) comprising a pump cover (14) and a pump body (16) for rotatably housing the impeller, and a motor part (70) for driving the impeller to rotate A fuel pump (10) comprising:
On each of the front and back surfaces of the impeller (20), a recess group (20b, 20c) that repeats in the circumferential direction is formed in a region extending in the circumferential direction with a predetermined distance from the outer periphery to the inside,
The pump cover (14) facing the impeller surface has a first groove (31) extending from the upstream end (31a) to the downstream end (31b) in a region facing the recess group (20c) of the impeller. And
The pump body (16) facing the impeller back surface is formed with a second groove (30) extending from the upstream end (30a) to the downstream end (30b) in a region facing the recess group (20b) of the impeller. And
The casing (18) includes a fuel discharge port (41) that communicates between the vicinity of the downstream end (31b) of the first groove (31) and the outside of the casing (18), and an upstream end of the second groove (30) ( 30a) a fuel inlet (40) communicating with the vicinity and outside of the casing (18) is formed,
When viewed in the rotational direction of the impeller, a seal is provided between the upstream end and the downstream end of the first groove (31) of the pump cover (14) and between the upstream end and the downstream end of the pump body (16). In the fuel pump provided with
A micron in which the amount of swelling of the recess group (20b, 20c) of the impeller (20) is predicted at a position facing the recess group (20b, 20c) of the impeller of at least one seal portion of the casing (18). A fuel pump characterized by forming a concave shape (35, 36) of the order.   The fuel pump according to claim 1, wherein the concave shape (35, 36) is formed in both the pump cover (14) and the pump body (16).   The shape of the concave group (20b, 20c) of the impeller (20) is a concave shape (50a, 50b) predicting the amount of swelling of the concave group of the impeller. Fuel pump. A disk-shaped impeller (20), a casing (18) comprising a pump cover (14) and a pump body (16) for rotatably housing the impeller, and a motor part (70) for driving the impeller to rotate A fuel pump (10) comprising:
On each of the front and back surfaces of the impeller (20), a recess group (20b, 20c) that repeats in the circumferential direction is formed in a region extending in the circumferential direction with a predetermined distance from the outer periphery to the inside,
The pump cover (14) facing the impeller surface has a first groove (31) extending from the upstream end (31a) to the downstream end (31b) in a region facing the recess group (20c) of the impeller. And
The pump body (16) facing the impeller back surface is formed with a second groove (30) extending from the upstream end (30a) to the downstream end (30b) in a region facing the recess group (20b) of the impeller. And
The casing (18) includes a fuel discharge port (41) that communicates between the vicinity of the downstream end (31b) of the first groove (31) and the outside of the casing (18), and an upstream end of the second groove (30) ( 30a) a fuel suction port (40) communicating with the vicinity of the outside of the casing (18) is formed,
Sealing portions between the upstream end and the downstream end of the first groove (31) of the pump cover (14) and between the upstream end and the downstream end of the pump body (16) when viewed in the impeller rotation direction, respectively. The shape of the recess group (20b, 20c) of the impeller (20) is a concave shape (50a, 50b) in which the amount of swelling of the recess group of the impeller is predicted. Features fuel pump.

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