JP7215979B2 - Fuel pump - Google Patents

Description

The present invention provides a fuel pump having a motor section and a pump section driven by the motor section, particularly a pump case body and a pump case body in which the pump section is joined to each other so as to define an impeller housing chamber therebetween. A pump case comprising a pump cover and a disk-shaped impeller rotatably and slidably housed in the impeller housing chamber and rotationally driven by a motor section are provided, and the impeller is located at or near the outer periphery of the impeller. The pump cover has a plurality of radial vanes arranged in the circumferential direction at a radially intermediate portion of the impeller, and the pump cover has a fuel intake port extending substantially along the rotation axis of the impeller and capable of sucking external fuel, and the fuel suction port. A groove-shaped pump that is recessed in the sliding surface of the pump cover with the impeller so that one end continues to the mouth and along the arrangement direction of the impeller blades, and pressurizes the fuel sucked from the fuel inlet in cooperation with the blades. It has a channel and a degassing hole capable of discharging air bubbles in the fuel flowing through the pump channel, and the pressurized fuel flowing through the pump channel can be discharged into the motor section from the fuel discharge port of the pump case. Regarding the fuel pump.

The above-mentioned fuel pump is conventionally known, for example, as disclosed in Patent Document 1. In this fuel pump, a groove-shaped pump flow path provided on the sliding surface of the pump cover with the impeller extends to the depth of the bottom surface of the groove. has a groove gradient that gradually becomes shallower from the fuel intake toward the front side in the rotational direction of the impeller, and the depth-changing flow path continues to the downstream end of the depth-changing flow path and the depth of the groove bottom surface is the flow path. A constant-depth channel portion that is constant over the entire direction is provided, and a degassing hole is opened in the middle of the constant-depth channel portion.

JP-A-2002-276581

In the fuel pump of Patent Document 1, the upstream portion of the pump flow path provided in the pump cover, which is connected to the fuel suction port, is a depth-changing flow path portion that gradually becomes shallower toward the front in the rotational direction of the impeller. Therefore, when the direction of fuel flow from the fuel inlet to the pump flow path changes from the direction along the rotation axis of the impeller to the direction of rotation of the impeller, the change is relatively gentle. As a result, the rapid deceleration of the fuel and the generation of violent turbulence are suppressed as much as possible, and the generation of vapor in the fuel is suppressed. In this case, the downstream end of the variable-depth channel portion and the upstream end of the constant-depth channel portion are connected to each other without any height difference on the bottom surface of the groove of the pump channel, so that the fuel flows smoothly along the bottom surface of the groove. flowing.

By the way, when the temperature is high, for example, when the fuel passes through a filter arranged upstream of the fuel inlet, a large amount of vapor is generated, and a large amount of vapor may flow from the fuel inlet into the pump channel at one time. could happen. In this case, as illustrated in FIG. 6, for example, a large amount of vapor fills the impeller blade grooves, making it impossible to introduce liquid fuel into the impeller blade grooves (that is, the grooves between adjacent blades). As a result, it may become difficult to pressurize the fuel by the impeller and, in turn, to discharge the fuel from the fuel pump.

SUMMARY OF THE INVENTION The present invention has been proposed in view of the above. The object is to provide a fuel pump.

To achieve the above object, the present invention comprises a motor section and a pump section driven by the motor section, the pump sections being joined together so as to define an impeller housing chamber therebetween. a pump case comprising a pump case main body and a pump cover; and a disk-shaped impeller rotatably and slidably accommodated in the impeller accommodation chamber and driven to rotate by the motor section. The impeller has a plurality of radial blades arranged in the circumferential direction at the outer peripheral portion of the impeller or at a radially intermediate portion near the outer peripheral end, and the pump cover extends substantially along the rotation axis of the impeller and can suck external fuel. a fuel inlet, and one end of which is continuous with the fuel inlet and recessed in the sliding surface between the impeller and the pump cover along the arrangement direction of the blades. It has a groove-shaped pump channel that pressurizes in cooperation with the vanes, and a degassing hole that can discharge air bubbles in the fuel flowing through the pump channel. In the fuel pump capable of discharging fuel into the motor section from a fuel discharge port of a pump case, the depth of the groove bottom surface of the pump channel is a groove that gradually becomes shallower from the fuel suction port toward the front side in the rotational direction of the impeller. A variable depth channel portion having a slope, and a constant depth channel portion connected to the downstream end of the variable depth channel portion and having a constant depth of the bottom surface of the groove throughout the direction of the channel. , at the downstream end of the variable-depth channel portion, the groove bottom surface of the variable-depth channel portion has the shallowest depth and is shallower than the constant-depth channel portion. A shallow portion is formed in the middle of the constant-depth channel portion formed downstream of the shallowest portion and deeper than the depth of the groove bottom surface of the shallowest portion, or downstream of the constant-depth channel portion. The first feature is that the inlet of the degassing hole is open to the pump flow path of the.

In the present invention, in addition to the first feature, the groove gradient is steeper at the downstream end portion of the variable depth channel portion than at the bottom surface of the groove at the intermediate portion in the channel direction of the variable depth channel portion. A second feature is that a steep slope portion is formed continuously with the shallowest portion.

Further, in addition to the first or second feature, the present invention includes an imaginary straight line connecting the rotational axis of the impeller and the center of the fuel inlet when viewed in a projection plane orthogonal to the rotational axis of the impeller, and the rotational axis. A third feature is that an angle formed by an imaginary straight line connecting the center of the air-releasing hole and the center of the air-releasing hole is 120 degrees or more.

Further, according to the present invention, in addition to any one of the first to third features, a fourth feature is that the depth of the bottom surface of the groove at the shallowest portion is set to 0.6 mm or less.

In the present invention and this specification, the "depth of the bottom surface of the groove" means the sliding surface of the pump cover with the impeller at the deepest part of the bottom surface of the groove as viewed in cross section (in the embodiment, the top surface of the pump cover ). For example, when the bottom surface of the flow channel groove is a groove having an arcuate cross section as in the embodiment, it refers to the depth of the widthwise central portion of the bottom surface of the groove from the sliding surface.

In the present invention, the “radial intermediate portion near the outer peripheral end” refers to a portion radially outward from the radial center position of the impeller (i.e., a virtual circle having a radius of 1/2 of the impeller radius). .

According to the first feature, the groove-shaped pump flow path, which is recessed in the sliding surface of the pump cover with the impeller and extends along the blade arrangement direction of the impeller, has a depth of the groove bottom surface extending from the fuel suction port to the impeller. A depth-changing channel portion having a groove gradient that gradually becomes shallower toward the front in the direction of rotation, and a bottom surface of the groove that continues to the downstream end of the variable-depth channel portion and has a constant depth throughout the channel direction. Since the constant depth channel portion is provided, when the direction of fuel flow from the fuel suction port to the pump channel changes from the direction along the rotation axis of the impeller to the direction of rotation of the impeller, the change in direction is minimized. It becomes relatively gentle, suppressing sudden deceleration of the fuel and severe turbulence, thereby suppressing the generation of vapor in the fuel.

Also, depending on the operating environment of the fuel pump, a large amount of vapor may flow into the impeller blade grooves from the fuel inlet and fill the impeller blade grooves. However, according to the first feature, at the downstream end of the variable depth channel portion, the constant depth channel portion having the shallowest depth of the groove bottom surface among the variable depth channel portions is provided. A shallowest portion that is shallower than the depth of the bottom of the groove is formed, and is formed downstream of the shallowest portion and is deeper than the depth of the bottom of the groove of the shallowest portion. Since the inlet of the degassing hole is open in the pump channel downstream of the constant channel portion, the liquid fuel flowing along the groove bottom surface of the depth varying channel portion is effectively drawn toward the impeller and throttled. The throttling effect accelerates the liquid fuel and pushes it strongly toward the blade side of the impeller. Therefore, the inside of the blade groove is pressurized by the liquid fuel introduced into the blade groove, and the vapor in the blade groove is gradually discharged from the degassing hole. , more liquid fuel is introduced into the blade grooves, and the blade grooves are finally filled with liquid fuel, so that it is possible to solve the pressurization failure of the fuel pump due to the inflow of a large amount of vapor. .
can be checked from the outside.

Moreover, by making the depth of the bottom surface of the groove of the constant-depth channel portion deeper than the shallowest portion of the variable-depth channel portion, it is possible to secure a sufficient pump discharge capacity.

According to the second feature, the downstream end portion of the variable depth channel portion has a steeper groove slope than the bottom surface of the groove in the intermediate portion in the channel direction of the variable depth channel portion. Since it is formed continuously with the shallow portion, the liquid fuel flowing along the bottom surface of the groove of the depth-changing channel portion can be more effectively brought to the impeller side in the vicinity of the impeller by the steep slope portion. Therefore, the liquid fuel can be pushed out more strongly toward the blades of the impeller, so that it is possible to more effectively eliminate the pressurization failure of the fuel pump caused by the inflow of a large amount of vapor.

Also, the vapor bubbles in the blade grooves of the impeller are gradually divided into small bubbles as the pressure inside the blade grooves increases as the impeller rotates. The angle formed by an imaginary straight line connecting the rotation axis and the center of the fuel inlet and an imaginary straight line connecting the rotation axis and the center of the vent hole is 120 degrees or more when viewed on a projection plane perpendicular to the rotation axis of , the pressure in the blade groove increases in the vicinity of the vent hole, and the bubbles in the vapor become sufficiently small. Therefore, the reduced vapor bubbles can be smoothly discharged from the degassing holes, so that the pressurization failure of the fuel pump due to the inflow of a large amount of vapor can be eliminated more effectively and quickly. .

According to the fourth characteristic, since the depth of the groove bottom surface of the shallowest portion of the downstream end portion of the depth-changing channel portion is set to 0.6 mm or less, the depth of the groove bottom surface of the shallowest portion can be appropriately brought close to the blades of the impeller, and the liquid fuel flowing along the bottom surface of the groove of the depth change flow passage can be more effectively squeezed toward the impeller side. The fuel can be accelerated more and pushed harder towards the blade side of the impeller. As a result, it is possible to more effectively and quickly solve the pressurization failure of the fuel pump caused by the inflow of a large amount of vapor.

1 is an overall longitudinal sectional view showing a fuel pump according to a first embodiment of the invention; (A) is a bottom view of the pump case body (enlarged cross-sectional view along line 2A-2A in FIG. 1), and (B) is a top view of the pump cover (enlarged cross-sectional view along line 2B-2B in FIG. 1). top view of impeller A vertical cross-sectional view of the pump part shown in a vertical cross-section passing through the fuel inlet and the first and second pump passages, and a partially enlarged cross-sectional view showing an enlarged partial region thereof (especially a large amount of vapor is the impeller blade groove It shows the state when it flows into and is filled inside) (a) is a cross-sectional view corresponding to the partially enlarged cross-sectional view of FIG. 4 showing the second embodiment, and (b) is a cross-sectional view corresponding to the partially enlarged cross-sectional view of FIG. 4 showing the third embodiment. Enlarged cross-sectional view corresponding to the partially enlarged view of FIG. 4, showing a comparative example

An embodiment of the present invention will be described below based on the accompanying drawings.

First, a first embodiment will be described with reference to FIGS. 1 to 4. FIG. The fuel pump PU is provided in a fuel supply system of an engine mounted on a vehicle (for example, an automobile, a motorcycle, etc.) and is used to pump fuel to a fuel injection device of the engine. It is installed and fixed in a tank (not shown) in an upright position as shown in FIG.

To explain an example of the fuel pump PU, it comprises a substantially cylindrical metal housing 10 with both upper and lower ends open, a synthetic resin cover member 11 closing the open upper end of the housing 10, a housing 10 , and a motor section 30 which is arranged above and adjacent to the pump section 20 and which is fitted to the inner circumference of the middle portion of the housing 10 . Next, the pump section 20 and the motor section 30 will be specifically described in order.

A conventionally well-known cascade pump is employed as the pump section 20. It includes, for example, a pump case 21 fitted and fixed to the inner circumference of the lower end portion of the housing 10 so as to close the open end on the lower side of the housing 10; A disk-shaped impeller 24 is rotatably slidably housed in the interior 21 and rotates in conjunction with a motor shaft 31, which will be described later. A lower end portion of the motor shaft 31 provided with a detent chamfer 31c is inserted into the center hole 24h1 of the impeller 24 so as to be non-rotatable and removable. Therefore, the rotation axis X of the motor shaft 31 coincides with the rotation axis of the impeller 24 .

The pump case 21 is divided into, for example, a disc-shaped pump case main body 22 and a disc-shaped pump cover 23 adjacent to the lower surface of the pump case main body 22. , an impeller housing chamber 25 in which the impeller 24 is rotatably and slidably housed is defined.

The pump case 21 is axially clamped and fixed, for example, between a downward inner peripheral stepped portion 10s at the bottom of the housing 10 and a locking claw portion 10a formed by caulking the open lower end of the housing 10 upward. The pressure between the joint surfaces of the pump case main body 22 and the pump cover 23 is oil-tightly sealed. An annular seal may be interposed, if necessary, between the joint surfaces in order to improve the sealing performance.

The impeller 24 integrally has a large number of radial blades 24b arranged in the circumferential direction at a radially intermediate portion near the outer peripheral end of the impeller 24, and radial blade grooves g are formed between the adjacent blades 24b. . Each blade 24b is formed, for example, in a V shape (see FIG. 4) that widens forward in the rotational direction a of the impeller 24 when viewed from the radially outer side of the impeller 24. becomes an inclined groove that opens on both sides of the That is, the opening direction of the groove g is inclined toward the outer side of the impeller 24 toward the rotation direction a of the impeller 24 .

In the illustrated example, the blades 24b of the impeller 24 are provided at a radially intermediate portion near the outer peripheral end of the impeller 24, but they may be provided at the outer peripheral portion of the impeller 24. FIG. In the illustrated example, the blades 24b of the impeller 24 are inclined with respect to the rotational direction a of the impeller 24, but blades perpendicular to the rotational direction a may be used.

The pump cover 23 includes a fuel suction port 23i extending substantially along the rotation axis X of the impeller 24 and capable of sucking external fuel (that is, fuel in the fuel tank). A C-shaped groove-shaped first pump passage P1 recessed in the sliding surface (upper surface in the illustrated example) of the pump cover 23 with the impeller 24 along the arrangement direction of the blades 24b, and the first pump passage P1. and a degassing hole 26 having an open entrance in the middle of the air. The outlet of the degassing hole 26 opens to the outer surface of the pump cover 23 so that air bubbles in the fuel flowing through the first pump flow path P1 can be discharged to the outside (that is, outside the fuel pump PU). Thus, the first pump channel P1 is an example of the pump channel of the present invention.

On the other hand, the pump case main body 22 is recessed in the sliding surface of the pump case main body 22 with the impeller 24 so as to face the first pump flow path P1 with the impeller 24 interposed therebetween. It has a flow path P2 and a fuel discharge port 22o that communicates the downstream end of the second pump flow path P2 with the inside of the housing 10 (in particular, the internal space of the motor section 30). Each of the first and second pump passages P1 and P2 is formed in a groove shape having a substantially arcuate cross section.

As will be described later, the first and second pump passages P1 and P2 cooperate with the blades 24b of the rotating impeller 24 to pressurize the fuel sucked from the fuel inlet 23i toward the fuel outlet 22o. It functions as a pressurized flow path for The pressurized fuel flowing through the first and second pump flow paths P1 and P2 is introduced into the motor portion 30 through the fuel discharge port 22o.

Further, the first pump flow path P1 includes a depth changing flow path portion 27 having a groove gradient in which the depth of the groove bottom surface gradually becomes shallower toward the front side in the rotational direction a of the impeller 24 from the fuel suction port 23i. A constant-depth channel portion 28 connected to the downstream end of the variable channel portion 27 and having a constant depth d1 of the bottom surface of the groove over the entire channel direction (for example, d1=0.6 mm in this embodiment). .

In addition, in the constant depth channel portion 28 of the present embodiment, the depth d1 of the groove bottom surface extends from the downstream end of the variable depth channel portion 27 to the vicinity of the downstream end of the first pump channel P1. The inlet of the degassing hole 26 is opened in the middle of the constant depth channel portion 28, but the channel portion near the degassing hole 26 and the degassing portion of the first pump channel P1 The channel portion on the downstream side of the pores 26 may be formed such that the depth of the groove bottom gradually decreases toward the downstream end.

Further, in the present embodiment, the groove width (that is, the width of the groove opening surface in the direction across the groove) of the depth-changing flow passage portion 27 is the maximum width at the portion communicating with the fuel suction port 23i, and the downstream side from there. formed so as to gradually narrow toward On the other hand, the constant-depth channel portion 28 has a substantially semicircular cross-section, and the width of the groove is constant over substantially the entire channel direction of the constant-depth channel portion 28 .

Between the downstream end portion 27d of the variable-depth channel portion 27 and the upstream end portion 28u of the constant-depth channel portion 28, the depth of the groove bottom surface of the constant-depth channel portion 28 is greater than the depth of the bottom surface of the groove. A stepped portion S is interposed to shallowly change the depth of the groove bottom surface of the portion 27d. Moreover, at the downstream end portion 27d of the variable depth channel portion 27, the constant depth channel portion 28 formed downstream of the variable depth channel portion 27 and having the shallowest groove bottom depth is provided. A shallowest portion 27dt shallower than the depth of the groove bottom surface by the step portion S is formed continuously on the high side of the step portion S.

Furthermore, at the downstream end portion 27d of the variable depth channel portion 27 of the present embodiment, there is a steep slope portion Z having a steeper groove gradient than the bottom surface of the groove at the intermediate portion in the channel direction of the variable depth channel portion 27. , to the upstream end of the shallowest portion 27dt.

A first bearing 51 made of metal (for example, nickel silver) is fitted (for example, press-fitted) into the center hole of the pump case main body 22 . The lower end of the motor shaft 31 is fitted and supported in the first bearing 51 so as to be removable. The upper end of the motor shaft 31 is rotatably fitted to and supported by the central portion of the inner wall of the cover member 11 via the second bearing 52 .

Further, central recesses 22a and 23a facing each other with the impeller 24 interposed therebetween are formed in the central portions of the opposing surfaces of the pump case main body 22 and the pump cover 23, respectively. The central recesses 22 a and 23 a communicate with each other through a communication hole 24 h 2 vertically penetrating the impeller 24 , and also communicate with the lower end of the motor shaft 31 and the lower end of the first bearing 51 .

Next, an example of the motor section 30 will be described. A conventionally well-known brushless motor is adopted as the motor unit 30. It includes, for example, a metallic stator core 32 whose outer peripheral portion is fixed (for example, press-fitted) to the housing 10, and at least both ends of the stator core 32 are fixed to the stator core 32. A synthetic resin insulator 33 covering the part, a coil 34 wound around the stator core 32 via the insulator 33, and a rotor with a magnet 35 that cooperates with the stator core 32 and the coil 34 to generate a rotational force. 36 and the motor shaft 31 that rotates with the rotor 36 .

The rotor 36 is provided with a synthetic resin cylindrical intermediate member 37 interposed between the magnet 35 and the motor shaft 31 to integrally couple the magnet 35 to the motor shaft 31 . As the intermediate member 37, a synthetic resin material excellent in abrasion resistance, such as polyacetal (POM) resin, is selected.

The magnet 35 has north and south poles arranged alternately in the circumferential direction, and is attached to the intermediate member 37 so as to surround the outer periphery thereof. Further, the inner peripheral portion of the intermediate member 37 is fixed to the outer periphery of the motor shaft 31, and as the fixing means, for example, press fitting, adhesion, insert molding, etc. can be appropriately adopted.

Between the opposing surfaces of the intermediate member 37 and the first bearing 51, a washer 40 made of metal (for example, stainless steel) is provided with a predetermined clamping force (corresponding to the total weight of the rotor 36 with the magnet 35 and the motor shaft 31 in this embodiment). It is clamped by the thrust force).

A connection terminal 38 leading to the coil 34 extends upward from the upper insulator 33 . The connecting terminal 38 has an intermediate portion press-fitted into a through hole of the cover member 11 and an upper end projecting upward from the cover member 11 so as to be detachably connected to an external wiring (not shown).

On the upper surface of the cover member 11, a fuel outlet pipe 11o is projected upward, which can discharge the pressurized fuel in the motor portion 30 to the fuel injection device side of the engine through an external pipe. A check valve 41 is provided in the fuel outlet tube 11o to allow the fuel to flow in only one direction from the inside of the motor portion 30 to the external piping side.

The cover member 11 is oil-tightly fitted and fixed (for example, press-fitted) to the upper inner periphery of the housing 10 until the lower end of the cover member 11 engages the upward inner peripheral step 10s' of the upper portion of the housing 10. As shown in FIG. A locking claw portion 10a' formed by crimping the open upper end of the housing 10 downward engages with the outer peripheral stepped portion of the cover member 11, thereby preventing the cover member 11 from being detached from the housing 10. be done.

Next, the operation of the first embodiment will be described.

When the motor portion 30 of the fuel pump PU is energized to rotate the motor shaft 31 , the impeller 24 of the pump portion 20 is rotationally driven in conjunction with the motor shaft 31 . Then, in the first and second pump passages P1 and P2, the fuel flows downstream while generating swirl and is gradually accelerated by the rotational direction pressing force and centrifugal force exerted by the blades 24b of the impeller 24 on the fuel. pressured. As a result, a negative pressure is generated at the fuel inlet 23i, and the fuel in the fuel tank is continuously drawn from the fuel inlet 23i into the upstream portions of the first and second pump flow paths P1 and P2. is pressurized by

Thus, when the impeller 24 of the pump section 20 is rotationally driven by the motor section 30, the fuel in the fuel tank is sucked into the pump case 21 from the fuel suction port 23i and flows through the first and second pump flow paths P1 and P2. gradually pressurized. Then, the pressurized fuel is discharged from the fuel discharge port 22o into the motor portion 30, from which it passes through the check valve 41 and is pressure-fed from the fuel outlet tube 11o to the external pipe and eventually to the fuel injection device of the engine. .

In the pump portion 20 of the present embodiment, the groove-shaped first pump flow path P1 is recessed in the sliding surface of the pump cover 23 with the impeller 24 and extends along the blade arrangement direction of the impeller 24. A depth-changing channel portion 27 having a groove gradient that gradually becomes shallower toward the front side in the rotational direction of the impeller 24 from the fuel intake port 23i, and a groove bottom surface connected to the downstream end of the depth-changing channel portion 27. A constant-depth channel portion 28 having a constant depth over the entire channel direction is provided. Therefore, during operation of the pump portion 20, when the flow direction of the fuel from the fuel suction port 23i toward the first pump flow path P1 changes from the direction along the rotation axis X of the impeller 24 to the rotation direction a of the impeller 24, , the direction change is relatively gradual, so that sudden fuel deceleration and severe turbulence are suppressed. As a result, it is possible to suppress the generation of vapor in the fuel, and in the unlikely event that vapor is generated, it can be quickly discharged from the degassing hole 26 .

However, depending on the operating environment of the fuel pump PU (for example, when the temperature is high), a large amount of vapor generated in the fuel tank, for example, in a filter or the like, may flow into the blade grooves g of the impeller 24 from the fuel inlet 23i at one time during pump operation. As a result, the impeller 24 may become difficult to pressurize the fuel because the impeller 24 may become unable to introduce the liquid fuel into the blade groove g.

This situation will be explained with reference to the comparative example shown in FIG. 6, for example. As a result, a large amount of vapor flows into and fills the blade groove g as shown in FIG. In some cases, the fluid is distributed in layers along the bottom surface of the groove and does not flow into the blade groove g. At this time, a vapor bubble layer exists between the liquid layer and the impeller 24, and the blade grooves g are filled only with vapor bubbles. is not effectively pressurized, and the vapor in the blade groove g is never discharged. Therefore, it becomes difficult to pressurize the fuel based on the rotation of the impeller 24 and, in turn, to discharge the fuel from the fuel discharge port 22o.

On the other hand, in this embodiment, as shown in the partial enlarged view of FIG. At the downstream end portion 27d of the variable depth channel portion 27, the constant depth channel portion 28 formed downstream of the variable depth channel portion 27 and having the shallowest groove bottom depth is provided. A shallowest portion 27dt shallower than the depth of the bottom of the groove is formed continuously on the high side of the stepped portion S.

As a result, the groove gradient of the downstream end portion 27d of the depth-changing flow passage portion 27 can be set larger than in the conventional structure (see FIG. 6) without the stepped portion S, and the depth-changing flow is greater than that in the conventional structure. Since the depth of the bottom surface of the groove of the downstream end portion 27d of the passage portion 27 can be made shallow, the liquid fuel flowing along the bottom surface of the groove of the depth changing passage portion 27 can be effectively brought closer to the impeller 24 side (that is, The liquid fuel can be throttled (while being deflected toward the impeller 24), and the throttle effect can accelerate the liquid fuel and push it strongly toward the blades 24b of the impeller 24.例文帳に追加

Therefore, the inside of the blade groove g is pressurized by the liquid fuel pushed out into the blade groove g, and the vapor in the blade groove g is gradually discharged from the degassing hole 26, and the liquid in the blade groove g is accompanied by the discharge. As the amount of fuel gradually increases (in other words, the fuel surface gradually rises), more liquid fuel is introduced into the blade groove g. Finally, the inside of the blade groove g is filled with the liquid fuel, so that the pressurization failure of the fuel pump PU caused by the inflow of a large amount of vapor can be eliminated, and the fuel can be discharged.

Further, even if the stepped portion S is eliminated and the groove depth of the constant-depth flow passage portion 28 is made as shallow as the shallowest portion 27dt, insufficient pressurization of the fuel pump PU due to the inflow of a large amount of vapor may occur. Although the problem can be expected to be resolved to some extent, in this case, the groove depth of the constant-depth flow path portion 28 becomes relatively shallow, and there is a possibility that the pump discharge capacity may be reduced.

On the other hand, in the present embodiment, the stepped portion S (that is, height difference) exists between the shallowest portion 27dt of the constant-depth channel portion 28 and the variable-depth channel portion 27. Since the groove depth of the constant-depth flow passage portion 28 can be formed relatively deep, a decrease in pump discharge capacity caused by excessively shallow groove depth of the constant-depth flow passage portion 28 can be avoided. That is, it becomes possible to sufficiently secure the pump discharge capacity.

In particular, in the present embodiment, the downstream end portion 27d of the variable depth channel portion 27 has a steep slope portion Z having a steeper groove gradient than the bottom surface of the groove in the intermediate portion of the variable depth channel portion 27 in the channel direction. , the upstream end of the shallowest portion 27dt. Therefore, by specially providing the steep slope portion Z, the liquid fuel flowing along the bottom surface of the groove of the depth-changing flow passage portion 27 can be more effectively brought toward the impeller 24 in the vicinity of the impeller 24, and the liquid fuel can be pushed out more strongly toward the blades 24b of the impeller 24. As a result, it is possible to more effectively eliminate the pressurization failure of the fuel pump PU caused by the inflow of a large amount of vapor.

Further, the vapor bubbles in the blade grooves g of the impeller 24 are gradually divided into small bubbles as the pressure in the blade grooves g increases as the impeller 24 rotates. 24, an imaginary straight line L1 connecting the rotation axis X and the center of the fuel inlet 23i and an imaginary straight line L2 connecting the rotation axis X and the center of the vent hole 26 are formed. The angle α is set to 120 degrees or more. As a result, the pressure in the blade grooves g increases in the vicinity of the degassing holes 26, and the vapor bubbles can be made sufficiently small, so that the vapor bubbles can be smoothly discharged from the degassing holes 26. As a result, It is possible to more effectively and quickly eliminate the pressurization failure of the fuel pump PU caused by the inflow of a large amount of vapor.

Further, in the present embodiment, the depth d2 of the groove bottom surface of the shallowest portion 27dt continuous to the high side of the stepped portion S is 0.6 mm or less (for example, the downstream end portion 27d of the depth-changing channel portion 27 is In the embodiment, it is desirable to set d2=0.5 mm). In that case, the groove bottom surface of the shallowest portion 27dt of the downstream end portion 27d of the variable depth channel portion 27 can be appropriately brought close to the blades 24b of the impeller 24, so that the variable depth channel portion 27 The liquid fuel flowing along the bottom surface of the groove can be throttled while being brought closer to the impeller 24 side more effectively. As a result, it is possible to more effectively and quickly eliminate the pressurization failure of the fuel pump PU caused by the inflow of a large amount of vapor.

Next, second and third embodiments will be described with reference to FIGS. 5(a) and 5(b). In the first embodiment described above, the downstream end portion 27d of the variable depth channel portion 27 has a steep slope portion Z having a groove gradient steeper than the bottom surface of the groove in the intermediate portion of the variable depth channel portion 27 in the channel direction. , formed continuously at the upstream end of the shallowest portion 27dt.

On the other hand, in the second embodiment shown in FIG. 5A, the bottom surface of the groove of the variable depth channel portion 27 is inclined at a constant gradient to the upstream end of the shallowest portion 27dt of the downstream end portion 27d. The steep section Z as in the first embodiment is omitted. The rest of the configuration of the second embodiment is similar to that of the first embodiment, so the constituent elements of the second embodiment are given the same reference numerals as the corresponding constituent elements of the first embodiment. , further description is omitted.

Therefore, in this second embodiment as well, at the downstream end 27d of the variable-depth channel portion 27, the depth of the groove bottom surface is the shallowest in the variable-depth channel portion 27 and the fixed-depth channel is provided. A shallowest portion 27dt that is shallower than the depth of the groove bottom surface of the portion 28 is formed, and a stepped portion S exists between the shallowest portion 27dt and the constant-depth flow passage portion 28 deeper than the shallowest portion 27dt. Therefore, also in the second embodiment, the depth of the groove bottom surface of the downstream end portion 27d of the depth-changing flow passage portion 27 can be made shallower than in the comparative example (FIG. 6) without the stepped portion S, and the depth Since the upward slope of the bottom surface of the groove of the variable flow path portion 27 is relatively large, substantially the same effects as those of the first embodiment can be expected.

Further, in the third embodiment shown in FIG. 5(b), the bottom surface of the groove of the variable depth channel portion 27 is inclined at a constant gradient to the shallowest portion 27dt of the downstream end portion 27d, similar to the second embodiment. , the steep section Z is omitted. In addition, there is no or almost no flat portion in the shallowest portion 27dt. The rest of the configuration of the second embodiment is similar to that of the first embodiment, so the constituent elements of the third embodiment are given the same reference numerals as the corresponding constituent elements of the first embodiment. , further description is omitted.

Therefore, also in this third embodiment, there is a stepped portion S between the shallowest portion 27dt of the variable-depth channel portion 27 and the constant-depth channel portion 28, which is deeper than the shallowest portion 27dt. Therefore, also in this third embodiment, the depth of the groove bottom surface of the downstream end portion 27d of the depth-changing flow passage portion 27 can be made shallower than in the comparative example (FIG. 6) without the stepped portion S, and the depth Since the upward slope of the bottom surface of the groove of the variable flow path portion 27 is relatively large, the same effects as those of the first and second embodiments can be expected.

Although the embodiment of the present invention has been described above, the present invention is not limited to the embodiment, and various design changes are possible without departing from the scope of the invention.

For example, in the above-described embodiment, the fuel pump PU is used for pressure-feeding fuel to a fuel injection device for an on-vehicle engine and arranged in the on-vehicle fuel tank. It may be used to pump fuel to an on-board engine fuel injector, or it may be located outside the fuel tank.

Further, in the above embodiment, the fuel pump PU is used in an upright posture, but in the present invention, the fuel pump PU may be used in other postures (for example, tilted posture, sideways posture).

Further, in the above embodiment, the motor section 30 is composed of a brushless motor, but the motor section may be a brush motor.

Further, in the above-described embodiment, the stepped portion S formed between the downstream end portion 27d of the variable depth channel portion 27 and the constant depth channel portion 28 is the downstream end portion 27d of the variable depth channel portion 27. Although an inclined surface descending from the constant-depth flow path portion 28 is shown, the stepped surface may be a curved surface (that is, an arcuate cross-section), or alternatively, the step surface may be a curved surface (that is, an arcuate cross-section). They may be orthogonal planes.

PU: Fuel pump P1: First pump flow paths L1, L2 as pump flow paths Imaginary straight line S: Stepped portion X: Rotational axis Z・・・ Steep slope part a ・・・ Rotation direction of impeller d2 ・・・・ Depth α of groove bottom surface at the shallowest part ・・・・ Angle 20 ・・・ Pump Part 21: pump case 22: pump case main body 22o: fuel discharge port 23: pump cover 23i: fuel intake port 24: impeller 24b . . . Blades 25 .. Impeller housing chamber 26 .. Degassing hole 27 . . . . Shallowest portion 28 at the downstream end portion .. Constant depth channel portion 30 .. Motor portion

Claims (4)

It comprises a motor section (30) and a pump section (20) driven by the motor section (30), wherein the pump sections (20) define an impeller housing chamber (25) therebetween. A pump case (21) consisting of a pump case body (22) and a pump cover (23) which are joined together, is rotatably slidably accommodated in the impeller accommodation chamber (25), and is rotationally driven by the motor section (30). The impeller (24) has a plurality of radial blades arranged in the circumferential direction at the outer peripheral portion of the impeller (24) or at a radially intermediate portion near the outer peripheral end of the impeller (24). (24b),
The pump cover (23) has a fuel suction port (23i) extending substantially along the rotation axis (X) of the impeller (24) and capable of sucking external fuel, and one end of the fuel suction port (23i). It is recessed in the sliding surface of the pump cover (23) with the impeller (24) so as to be continuous and along the arrangement direction of the vanes (24b). (24b) to pressurize in cooperation with a groove-shaped pump channel (P1), and a degassing hole (26) capable of discharging air bubbles in the fuel flowing through the pump channel (P1), In a fuel pump in which pressurized fuel flowing through the pump flow path (P1) can be discharged from a fuel discharge port (22o) of the pump case (21) into the motor section (30),
The pump channel (P1) has a groove gradient in which the depth of the groove bottom surface gradually decreases from the fuel suction port (23i) toward the front side in the rotational direction (a) of the impeller (24). A channel portion (27), and a constant depth channel portion (28) connected to the downstream end of the variable depth channel portion (27) and having a constant depth of the bottom surface of the groove over the entire channel direction. At the downstream end (27d) of the variable depth channel portion (27), the constant depth stream having the shallowest depth of the groove bottom surface among the variable depth channel portions (27) is provided. A shallowest portion (27dt) shallower than the depth of the bottom of the groove of the path (28) is formed ,
In the middle of the constant-depth channel portion formed downstream of the shallowest portion (27dt) and deeper than the depth of the bottom surface of the shallowest portion (27dt), or from the constant-depth channel portion (28) A fuel pump , wherein an inlet of said degassing hole (26) opens into said pump flow path (P1) on the downstream side . At the downstream end (27d) of the variable depth channel portion (27), there is a steep slope portion in which the groove gradient is steeper than the bottom surface of the groove at the intermediate portion in the channel direction of the variable depth channel portion (27). 2. The fuel pump according to claim 1, wherein (Z) is formed continuously with said shallowest portion (27dt). An imaginary straight line (L1) connecting the rotation axis (X) and the center of the fuel inlet (23i) when viewed in a projection plane orthogonal to the rotation axis (X) of the impeller (24); 3. A fuel pump according to claim 1 or 2, characterized in that an angle ([alpha]) formed by an imaginary straight line (L2) connecting X) and the center of said vent hole (26) is 120 degrees or more. A fuel pump according to any one of claims 1 to 3, characterized in that the depth (d2) of the groove bottom surface of said shallowest portion (27dt) is set to 0.6 mm or less.

Images