KR100904601B1 - Fuel pump and fuel feed apparatus having the same - Google Patents

Abstract

The fuel pump 30 includes an impeller 70 having first and second vane grooves 74 and 76 arranged along the rotational direction, respectively. The second vane groove 76 is located radially inward of the first vane groove 74. The fuel pump 30 includes pump cases 50, 52 that rotatably receive the impeller 70 and have first and second pump passages 202, 206. The first pump passage 202 is formed along the first vane groove 74 to supply fuel from the sub tank 20 to the engine 500. The second pump passage 206 is formed along the second vane groove 76 to supply fuel from the fuel tank 2 to the sub tank 20. The first and second pump passages 202 have diameters D1 and D2, respectively, with respect to the cross-sectional areas S1 and S2 and the rotation axis directions of the impellers 70 and 51, respectively. The cross-sectional areas S1 and S2 and the diameters D1 and D2 satisfy 0.6 ≦ (S2 × D2) / (S1 × D1) ≦ 0.95.

Fuel pump, vane groove, pump passage, impeller, fuel tank, sub tank

Description

FUEL PUMP AND FUEL FEED APPARATUS HAVING THE SAME

The present invention relates to a fuel pump comprising an impeller having two lines of vane grooves located at different positions in the radial direction. The invention also relates to a fuel supply apparatus having a fuel pump for supplying fuel from a sub tank to an engine while simultaneously supplying fuel from the fuel tank to the sub tank.

As is generally known, a fuel pump is provided in a sub tank housed within the fuel tank for pumping fuel from the sub tank to the internal combustion engine. For example, US Pat. Nos. 5,596,970 and 6,179,579 (JP-A-2002-500718) disclose such fuel pumps each including a fuel pump that supplies fuel from a fuel tank to a sub tank without using a jet pump. Doing.

In each of US Pat. Nos. 5,596,970 and 6,179,579, the fuel pump includes an impeller having two lines of vane grooves positioned at different positions in the radial direction, and two lines of vane grooves rotatably receiving the impeller. It includes a pump case having a pump passage along. The impeller rotates to draw fuel from the sub tank to supply fuel to the engine through a pump passage extending along the vane groove on the radially outer side. The impeller also draws fuel from the fuel tank and supplies fuel to the sub tank through a pump passage extending along the vane groove on the radially inner side.

The fuel pump supplies Q1 fuel to the engine and Q2 fuel to the sub tank. In such a fuel pump, the values Q1 and Q2 need to satisfy the relationship Q2 ≧ Q1 even when the engine needs the maximum amount while the engine provides the maximum power. If the amount Q2 of fuel supplied from the fuel tank to the sub tank is less than the amount Q1 of fuel supplied from the sub tank to the engine (Q2? Q1), the level of the sub tank is reduced, and thus the fuel pump draws fuel from the sub tank. Can not. Therefore, the fuel pump needs to be configured to have two lines of vane grooves, and the pump passage is configured to satisfy the relationship of Q2 ≧ Q1 and to prevent the level of the sub tank from decreasing.

The pressure of the fuel pumped from the sub tank to the engine is significantly greater than the fuel pressure pumped from the fuel tank to the sub tank. Therefore, the pressure difference of the fuel passage which pumps fuel from the sub tank to the engine is larger than the pressure difference of the fuel passage which pumps fuel from the fuel tank to the sub tank in terms of the rotational direction of the impeller. When the pressure difference in the pump passage becomes large, the fuel is forced in a direction opposite to the rotational direction, so that the pump efficiency of the fuel pump decreases. In addition, when the fuel is pressurized to a high pressure, the amount of fuel leaked through the gap between the pump case and the impeller becomes large, thereby reducing the pump efficiency. Therefore, the fuel pump needs to be designed in consideration of the increased fuel pressure through the pump passage and the amount of fuel supplied from the fuel pump. Here, pump efficiency (eta) is defined as (eta) = (PxQ) / (TxR). Where T is the torque provided by the motor portion of the fuel pump, R is the rotational speed of the motor portion, P is the discharge pressure of the fuel after passing through the pump passage, and Q is the discharged fuel after passing through the pump passage. Amount.

No. 5,596,970 and 6,179,579 do not disclose fuel pumps configured to prevent the level of the sub tank from decreasing in view of the fuel pressure in the pump passage.

In view of the above and other problems, an object of the present invention comprises a fuel pump comprising an impeller having two lines of vane grooves and configured to adjust the amount of fuel supplied from the fuel tank to the sub tank in consideration of the fuel pressure in the pump passageway. To provide. Another object of the present invention is to provide a fuel supply apparatus having a fuel pump for supplying fuel from a fuel tank to a sub tank while simultaneously supplying fuel from the sub tank to the engine.

According to one aspect of the present invention, there is disclosed a fuel pump for supplying fuel from a fuel tank to a sub tank contained within the fuel tank and for supplying fuel to the engine from the sub tank, wherein the fuel pumps are each arranged along a rotational direction thereof. And an impeller having a plurality of first vane grooves and a plurality of second vane grooves. The plurality of second vane grooves is located radially inward of the plurality of first vane grooves with respect to the radial direction of the impeller. The fuel pump further includes a pump case rotatably receiving the impeller and having a first pump passageway and a second pump passage respectively formed along the rotational direction. The first pump passage is formed along the first vane groove for supplying fuel from the sub tank to the engine. The second pump passage is formed along the second vane groove for supplying fuel from the fuel tank to the sub tank. The first and second pump passages have cross sections S1 and S2, respectively. The first and second pump passages each have diameters D1 and D2 in the direction of the axis of rotation of the impeller. The cross-sectional areas S1 and S2 and the diameters D1 and D2 satisfy 0.6 ≦ (S2 × D2) / (S1 × D1) ≦ 0.95.

According to another aspect of the present invention, a fuel supply device for supplying fuel from a fuel tank to an engine is disclosed, wherein the fuel supply device includes a sub tank contained within the fuel tank. The fuel supply apparatus further includes a fuel pump housed in the sub tank to supply fuel from the fuel tank to the sub tank at the same time. The fuel pump includes an impeller having a plurality of first vane grooves and a plurality of second vane grooves each arranged along a rotational direction of the impeller, wherein the plurality of second vane grooves are radially inward of the plurality of first vane grooves. Is located. The fuel pump further includes a pump case rotatably receiving the impeller and having first and second pump passages respectively formed along the direction of rotation. The first pump passage extends along the first vane groove. The first pump passage is in communication with an inlet located inside the sub tank for sucking in fuel and in communication with an outlet for supplying fuel to the engine. The second pump passage extends along the second vane groove. The second pump passage is located outside the sub tank and communicates with an opening opened to the fuel tank to draw fuel from the fuel tank, and communicates with an outlet opened to the sub tank to supply fuel to the sub tank. The first and second pump passages have cross sections S1 and S2, respectively. The first and second pump passages each have diameters D1 and D2 in the direction of the axis of rotation of the impeller. The cross-sectional areas S1 and S2 and the diameters D1 and D2 satisfy 0.6 ≦ (S2 × D2) / (S1 × D1) ≦ 0.95.

The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings.

According to the present invention, it is possible to provide a fuel pump comprising an impeller having two lines of vane grooves and configured to adjust the amount of fuel supplied from the fuel tank to the sub tank in consideration of the fuel pressure in the pump passage.

(First embodiment)

1 to 5, a first embodiment is described. 2 shows a fuel pump according to a first embodiment. In Fig. 2, the thick arrows indicate the flow direction of the fuel. The fuel supply device 10 is accommodated in the fuel tank 2 with the sub tank 20 of the fuel supply device 10 accommodating the fuel pump 30. The fuel pump 30 is an in-tank pump provided inside a fuel tank of a vehicle such as a two-wheeled vehicle and a four-wheeled vehicle.

The sub tank 20 is substantially formed of resin of, for example, a lower cylindrical or rectangular box shape. The sub tank 20 has a lower wall 22 provided with leg portions 23 which respectively protrude toward the lower wall 3 of the fuel tank 2. The leg 23 is in contact with the lower wall 3 of the fuel tank 2. A leg 23 is provided between the lower wall 22 of the sub tank 20 and the lower wall 3 of the fuel tank 2 to form a space 210.

The fuel pump 30 includes a motor portion 32 and a pump portion 34. The motor unit 32 drives the pump unit 34. The housing 36 houses the motor portion 32 and the pump portion 34. The housing 36 has two axial ends each crimped and fixed to the end cover 38 and the pump case 50. The end cover 38 is formed of resin. The end cover 38 has a discharge port 39 through which the fuel pump 30 supplies fuel to the internal combustion engine 500.

The motor unit 32 is a DC motor having a permanent magnet, a rectifier, a brush, a choke coil, a rotor 40, and the like. Each permanent magnet is virtually arcuate. The permanent magnets are arranged in the circumferential direction along the inner circumference of the housing 36.

The rotor 40 is rotatable in the radially inner side of the permanent magnet. The rotor 40 has a shaft 42 rotatably supported by a metal bearing 44 at both axial ends. 2 shows one of the metal bearings 44 at one axial end of the shaft 42. The bearing 44 is supported by the pump case 52. Rotor 40 includes a rotor core and a coil. The rotor core has a plurality of magnet cores arranged along the direction of rotation. The coils are each wound around a magnet core. The coil of the rotor 40 is supplied with a drive current through a brush and a rectifier.

The pump portion 34 is a turbine pump including the pump cases 50 and 52 and the impeller 70. The pump portion 34 is provided at one axial end of the rotor 40 of the motor portion 32. Each pump case 50, 52 is a case member formed of a metal material or resin, such as aluminum, which is excellent in fuel resistance and mechanical strength. The pump cases 50 and 52 rotatably receive the impeller 70. The pump case 50 covers the pump portion 34 on the sub tank 20 side. The pump case 52 covers the pump portion 34 on the rotor 40 side.

The impeller 70 is made of a resin having excellent resistance to fuel and excellent mechanical strength, and is formed in a substantially disk shape.

As shown in Fig. 1, the impeller 70 has an annular portion 72 forming its outer periphery. The impeller 70 has a plurality of vane grooves 74 radially inward of the annular portion 72. The vane grooves 74 are arranged radially. The vane groove 74 functions as the first vane groove 74. The impeller 70 has a plurality of vane grooves 76 radially inward of the vane grooves 74. The vane grooves 76 are arranged radially. The vane groove 76 is located at a position different from the vane groove 74 in the radial direction of the impeller 70. The vane groove 76 functions as the second vane groove 76.

The vane grooves 74, 76 are provided on both axial sides of the impeller 70. The vane grooves 74, 76 provided on both axial sides of the impeller 70 communicate with each other. Fuel flows into the vane grooves 74 and 76 and the fuel forms a vortex flow 300 in the vane grooves 74 and 76 on both axial sides. The vane grooves 74 and 76 adjacent to each other in the rotational direction are divided by partition walls 75 and 77, respectively.

The pump cases 50, 52 on the axial side of the impeller 70 are substantially C shaped first and second pump passages 202, 206 along the vane grooves 74, 76 in the rotational direction of the impeller 70, respectively. ). The first pump passage 202 functions as a first pump passage communicating with the vane groove 74. The second pump passage 206 functions as a second pump passage in communication with the vane groove 76.

Referring to FIG. 2, the pump case 50 has a fuel inlet 201 of the first pump passage 202. The pump case 52 has a fuel outlet 203 of the first pump passage 202. The fuel inlet 201 opens inwardly of the sub tank 20. The fuel outlet 203 of the first pump passage 202 opens to the fuel chamber 208 of the motor portion 32. The fuel inlet 201 is provided with a suction filter for removing foreign matter contained in the fuel flowing from the sub tank 20.

The pump case 50 has a fuel inlet 205 and a fuel outlet 207 of the second pump passage 206. The fuel inlet 205 is a through hole extending through the bottom wall 22 of the sub tank 20. The fuel inlet 205 opens to the outside of the sub tank 20 and to the inside of the fuel tank 2. The fuel outlet 207 opens to the inside of the sub tank 20. The lower wall 22 of the sub tank 20 has a lower inner periphery which forms a through hole through which the fuel inlet 205 extends. An elastic member 64 formed of an elastic material is interposed between the lower inner periphery of the lower wall 22 and the fuel inlet 205 to be substantially cylindrical. The elastic member 64 functions as a seal member. The elastic member 64 prevents fuel from leaking from the through hole of the lower wall 22. The fuel inlet 205 is provided with a check valve 66 which prevents fuel from flowing back into the fuel tank 2 from the sub tank 20. A check valve 66 is provided at the fuel inlet 205 to prevent backflow of fuel into the fuel tank 2 at the fuel pump 30. Therefore, the fuel pump 30 can accumulate fuel even when the fuel pump 30 is stopped. Accordingly, the fuel pump 30 may rapidly suck fuel through the fuel inlet 205 to supply fuel from the fuel tank 2 to the sub tank 20 with the fuel pump 30 starting to operate. Can be. The fuel inlet 205 is provided with a suction filter 62 for removing foreign matter in the fuel flowing from the fuel tank 2. The suction filter 62 is provided in the space 210 formed between the lower wall 22 of the sub tank 20 and the lower wall 3 of the fuel tank 2.

Referring to FIG. 2, when the rotor 40 is operated, the impeller 70 moves the shaft 42 to suck fuel through the fuel inlets 201 and 205 into the first and second pump passages 202 and 206. Rotate with). The fuel flows in and out between the vane grooves 74 and 76 on the front side and the vane grooves 74 and 76 on the rear side with respect to the rotational direction. The fuel repeats inflow and outflow to form a vortex flow 300 that is pressurized through the first and second pump passages 202, 206.

The impeller 70 rotates to draw fuel from the sub tank 20 through the fuel inlet 205, and the fuel is pressurized through the first pump passage 202 on both sides with respect to the axis of rotation. The fuel is combined at the fuel outlet 203 of the pump case 50 on the motor part 32 side. Thus, fuel is discharged into the fuel chamber 208 of the motor portion 32 through the fuel outlet 203. Fuel discharged into the fuel chamber 208 through the fuel outlet 203 passes through the gap between the outer periphery of the rotor 40 and the inner periphery of the British magnet. Thus, fuel is supplied to the engine 500 through the exhaust port 39 of the end cover 38. In this operation, the fuel pressurized in the pump portion 34 flows through the motor portion 32 so that the fuel cools the motor portion 32 and lubricates the active portions inside the motor portion 32.

The amount of fuel discharged to the engine 500 through the discharge port 39 is about 20 to 300 L / h. This amount of fuel discharged through the discharge port 39 is equal to the amount of fuel discharged through the fuel outlet 203 of the first pump passage 202. The rotation speed of the impeller 70 is about 4000 to 15000 rpm.

The impeller 70 rotates to draw fuel from the fuel tank 2 through the fuel inlet 205, and the fuel is pressurized through the second pump passage 206 on both sides with respect to the axis of rotation. The fuel is combined at the fuel outlet 207 of the pump case 50 and discharged to the sub tank 20 through the fuel outlet 207.

Here, the amount of fuel supplied from the first pump passage 202 is Q1. The diameter of the first pump passage 202 about the axis of rotation of the impeller 70 is D1. The cross-sectional area of the first pump passage 202 is S1. The amount of fuel supplied from the second pump passage 206 located radially inward of the first pump passage 202 is Q2. The diameter of the second pump passage 206 about the axis of rotation of the impeller 70 is D2. The cross-sectional area of the second pump passage 206 is S2. The rotational speed per minute of the impeller is R rpm. The values Q1 and Q2 are defined by the following formulas (1) and (2). In this structure, the first and second pump passages 202, 206 are provided on both sides of the impeller 70 with respect to the axis of rotation, and the values S1, S2 are the first and second pumps on both sides of the impeller 70. It is the sum of the cross-sectional areas of the passages 202, 206.

Q1 = π × S1 × D1 × R (1)

Q2 = π × S2 × D2 × R (2)

Thus, when fuel is supplied from the sub tank 20 to the engine 500, Q2 ≧ Q1 is the first and second pump passages (i.e., without consideration of fuel pressure in the first and second pump passages 202,206). The amount of fuel passing through 202 and 206 is taken into account to maintain the level in the sub tank 20. That is, the following formula (3) satisfies maintaining the level of the sub tank 20.

Q2≥Q1

π × S2 × D2 × R ≥ π × S1 × D1 × R

(S2 × D2) / (S1 × D1) ≥ 1 (3)

However, the pressure in the first pump passage 202 through which the fuel supplied from the sub tank 20 to the engine 500 is pressurized is the second through which the fuel supplied from the fuel tank 2 to the sub tank 20 is pressurized. Higher than the pressure in the pump passage 206. Therefore, the decrease in the discharge amount Q1 of the first pump passage 202 defined by equation (1) is greater than the decrease in the discharge amount Q2 of the second pump passage 206 defined by equation (2). Therefore, if the cross-sectional areas S1, S2 and the diameters D1, D2 are simply determined to satisfy the formula (3), the actual value of the discharge amount Q2 becomes excessively larger than the actual value of the discharge amount Q1. As a result, fuel is excessively supplied from the fuel tank 2 to the sub tank 20.

In the following, the design values of the impeller 70 and the first and second pump passages 202, 206 are described.

The impeller 70 has an outer diameter of 20 to 50 mm. The first and second pump passages 202, 206 are formed along the vane grooves 74, 76 on both sides with respect to the axis of rotation. The first pump passage 202 on one side with respect to the axis of rotation has a cross-sectional area S1. The second pump passage 206 on one side with respect to the axis of rotation has a cross-sectional area S2. Each cross-sectional area S1, S2 is 2 to 8 mm ² . The discharge amount of fuel through the first pump passage 202 is Q1, the diameter of the first pump passage 202 with respect to the axis of rotation of the impeller 70 is D1, and the discharge amount of fuel through the second pump passage 206 is Q2, the diameter of the second pump passage 206 relative to the axis of rotation of the impeller 70 is D2, and the rotational speed of the impeller 70 is R per minute. The values of the discharge amounts Q1 and Q2 are defined by the above formulas (1) and (2). In the formulas (1) and (2), S1 is replaced by 2 x S1 and S2 by 2 x S2. The diameter D1 is the distance between the center 100 of the width W1 of the first pump passage 202 and the center 100 of the width W1 with respect to the radial direction of the impeller 70. The diameter D2 is the distance between the center 102 of the width W2 of the second pump passage 206 and the center 102 of the width W2 with respect to the radial direction of the impeller 70.

Here, Q2? Q1 satisfies maintaining the level of the sub tank 20 even when fuel is supplied from the sub tank 20 to the engine 500 outside the fuel tank 2. That is, equation (3) satisfies limiting the level reduction of the sub tank 20.

The pressure of the fuel pressurized through the first pump passage 202 is higher than the pressure of the fuel pressurized through the second pump passage 206. Fuel is pressurized through the first pump passage 202 to be the fuel pressure P1 and supplied from the fuel pump 30 to the engine 500. The fuel is also pressurized through the second pump passage 206 to be fuel pressure P2 and fed from the fuel pump 30 to the sub tank 20. For example, the fuel pressure P1 needs to be 200 to 800 kPa. In comparison, the fuel pressure P2 needs to be at most 50 kPa. Accordingly, a pressure difference occurs in the first and second pump passages 202 and 206 with respect to the rotation direction, and a force is applied to the fuel in each of the first and second pump passages 202 and 206 opposite to the rotation direction. You lose. The force exerted on the fuel in the first pump passage 202 is greater than the force exerted on the fuel in the second pump passage 206. This pressure difference further causes fuel leakage in the first and second pump passages 202, 206 through respective gaps between the pump cases 50, 52 and the impeller 70. The fuel leak from the first pump passage 202 is greater than the fuel leak from the second pump passage 206. Therefore, the decrease in the discharge amount Q1 of the first pump passage 202 defined in equation (1) is greater than the decrease in the discharge amount Q2 of the second pump passage 206 defined in equation (2). If the cross-sectional areas S1, S2 and diameters D1, D2 are simply determined to satisfy equation (3), the actual value of the discharge amount Q2 becomes excessively larger than the actual value of the discharge amount Q1. As a result, the discharge amount Q2 of the fuel supplied from the fuel tank 2 to the sub tank 20 becomes excessively large. It is sufficient that fuel is supplied to the sub tank 20 so that the level of the sub tank 20 is maintained. In other words, the fuel does not need to be excessively supplied from the fuel tank 2 to the sub tank 20.

Therefore, the range of (S2 × D2) / (S1 × D1) needs to be determined in consideration of the range of the fuel pressure P1 pressurized through the first pump passage 202. The fuel pressurized through the first pump passage 202 and supplied from the fuel pump 30 to the engine 500 is, for example, within a fuel pressure P1 between 200 and 800 kPa. Therefore, the range of (S2 × D2) / (S1 × D1) needs to be determined such that the fuel pressure P1 becomes 200 to 800 kPa, for example, and the actual value of Q2 / Q1 is possibly 1. Equation (4) below is obtained from FIG.

0.6 ≤ (S2 × D2) / (S1 × D1) ≤ 0.95 (4)

The range of (S2 × D2) / (S1 × D1) is determined in a range determined by equation (4) so that the fuel pressure P1 becomes 200 to 800 kPa, and the actual value of Q2 / Q1 is possibly 1.

In addition, the vortex flow 300 passing along the first pump passage 202 and the vane groove 74 is preferably circular in shape. Also, the vortex flow 300 passing along the second pump passage 206 and the vane groove 76 is also preferably circular in shape. When the vortex stone flow 300 is substantially circular in shape, the pump efficiency η of the vortex flow 300 is improved by possibly reducing the loss of kinetic energy caused by the drastic change in the flow direction of the vortex flow 300. Can be.

The first and second pump passages 202 and 206 have depths H1 and H2 along the axis of rotation of the impeller 70, respectively. The depths H1, H2 of the first and second pump passages 202, 206 are the depths of the vane grooves 74, 76 with respect to the thickness direction of the impeller 70 such that the swirl flow 300 is formed in a substantially circular shape, respectively. And are virtually identical to each other. Each of the depths H1, H2 of the first and second pump passages 202, 206 is in fact 1/2 of the thickness t of the impeller 70. Thus, equations (5) and (6) satisfy that the vortex flows 300 are each formed in a substantially circular shape.

H1 / t = 0.5 (5)

H2 / t = 0.5 (6)

Indeed, when each value H1 / t, H2 / t is within a predetermined range including 0.5, each vortex flow 300 may not be excessively flat. Equations (7) and (8) below are obtained from FIG. 4 to form a range of H1 / t and H2 / t satisfying η1 ≥ 40% and η2 ≥ 10%, respectively. The ranges defined by the formulas (7) and (8) include the maximum values of the pump efficiencies η 1 and η 2 of the first and second pump passages 202 and 206, respectively.

0.3 ≤ H1 / t ≤ 0.6 (7)

0.2 ≤ H2 / t ≤ 0.6 (8)

The pump efficiency of the second pump passage 206 is lower than that of the first pump passage 202, so it is particularly desirable to satisfy equation (8).

The fact that twice the values of the depths H1 and H2 of the pump passages is substantially the same as the widths W1 and W2 of the first and second pump passages 202 and 206 with respect to the radial direction of the impeller 70, respectively, results in a vortex flow 300. Virtually satisfactory to form in a circle. That is, equations (9) and (10) satisfy the fact that the vortex flow 300 is formed in a substantially circular shape.

2 = W1 / H1 (9)

2 = W2 / H2 (10)

Indeed, when the respective values of W1 / H1 and W2 / H2 are within a predetermined range including two, the flow direction of each vortex flow 300 is not excessively flat. Equations (11) and (12) below are obtained from Fig. 5 to determine the ranges of W1 / H1 and W2 / H2 that satisfy? 1? 40% and? 2? 10%, respectively. The range defined by equations (11) and (12) includes the maximum values of the pump efficiencies η 1 and η 2 in the first and second pump passages 202 and 206, respectively.

1.5 ≤ W1 / H1 ≤ 2.1 (11)

1.9 ≤ W2 / H2 ≤ 2.5 (12)

The pump efficiency η 2 in the second pump passage 206 is lower than the pump efficiency η 1 of the first pump passage 202, and therefore it is particularly desirable to satisfy equation (12).

In this embodiment, the fuel pump 30 has vane grooves 74 and 76 at different positions with respect to the radial direction of the impeller 70. The fuel pump 30 supplies fuel from the sub tank 20 to the engine 500, and also supplies fuel from the fuel tank 2 to the sub tank 20. In the fuel pump 30, the first and second pump passages 202, 206 have cross-sectional areas S1, S2, respectively, and the first and second pump passages 202, 206 are respectively axial in the impeller 70. Have diameters D1 and D2. Also, in particular, the range of (S2 × D2) / (S1 × D1) is determined to satisfy the formula (3) in consideration of the pressure of the first pump passage 202 to which the fuel supplied to the engine 500 is pressurized. . Therefore, the decrease in the fuel level of the sub tank 20 is prevented, and the amount of fuel supplied from the fuel tank 2 to the sub tank 20 is prevented from excessively increasing.

Further, the thicknesses t of the depths H1, H2 and impeller 70 of the first and second pump passages 202, 206 are such that H1 / t and H2 / t are in the ranges defined by equations (7) and (8). It is suitably limited. The depths H1, H2 and widths W1, W2 of the first and second pump passages 202, 206 with respect to the radial direction are suitably such that W1 / H1 and W2 / H2 are in the ranges defined by equations (11), (12). It is limited. Thus, the swirl flow 300 formed between the first pump passage 202 and the vane groove 74 is limited to become flat. In addition, the swirl flow 300 formed between the second pump passage 206 and the vane groove 76 is also limited to a flat shape. Thus, the pump efficiency is improved.

In this embodiment, the cross-sectional areas S1 and S2 of the first and second pump passages 202 and 206 and the diameters D1 and D2 take the equation (4) in consideration of the pressure of the first and second pump passages 202 and 206. It is formed to satisfy.

0.6 ≤ (S2 × D2) / (S1 × D1) ≤ 0.95 (4)

Therefore, the quantity Q2 of fuel supplied from the fuel tank 2 to the sub tank 20 is supplied from the sub tank 20 to the engine 500 by satisfying the formula 0.6? (S2 x D2) / (S1 x D1). Excessively less than the quantity Q1 of fuel to be used is prevented. Also, the quantity Q2 of fuel supplied from the fuel tank 2 to the sub tank 20 is supplied from the sub tank 20 to the engine 500 by satisfying the formula (S2 × D2) / (S1 × D1) ≦ 0.95. Excessively larger than the amount Q1 of fuel to be used is prevented. Therefore, the amount of fuel supplied from the fuel tank 2 to the sub tank 20 is prevented from becoming excessively large, and the level of the sub tank 20 is adjusted to satisfy the equation (4). The reduction is limited by determining the cross-sectional areas S1, S2 and diameters D1, D2 of 202, 206.

The fuel pressure supplied to the first pump passage is P (kPa) satisfying 200 ≦ P ≦ 800. The amount of fuel supplied from the fuel tank 2 to the sub tank 20 is prevented from becoming excessively large, and the level of the sub tank 20 is satisfied so as to satisfy the formula (4) with a pressure in the range of 200 ≦ P ≦ 800. The reduction is limited by determining the cross-sectional areas S1, S2 and diameters D1, D2 of the first and second pump passages 202, 206.

The fuel in the first and second pump passages 202, 206 flows out from one of the vane grooves 74, 76 on the front side with respect to the rotational direction by the rotation of the impeller 70, and the vane groove 74 on the rear side. 76, repeats the inflow to the other, so that the fuel forms a vortex flow 300 as it is pressurized. The vortex flow 300 preferably has a circular shape in cross section of each passage including the first and second pump passages 202, 206 and the vane grooves 74, 76. The vortex flow 300 has a substantially circular shape in cross section so that the vortex flow 300 is limited in the sharp change in the flow direction, and the vortex flow 300 maintains kinetic energy. Therefore, the pump efficiencies η 1 and η 2 of the first and second pump passages 202 and 206 are improved. Each of the depths H1, H2 of the first and second pump passages 202, 206 are each vane groove 74, 76 relative to the thickness direction of the impeller 70 to form a substantially circular vortex flow 300. Is virtually equal to the depth of As defined by equations (5) and (6), each of the depths H1, H2 of each of the first and second pump passages 202, 206 is substantially one half of the thickness t of the impeller 70. Indeed, when H / t is in a predetermined range including 0.5, the vortex flow 300 is not excessively flat.

H1 = t / 2

H2 = t / 2

H1 / t = 0.5 (5)

H2 / t = 0.5 (6)

The second pump passage 206 has a depth H2 with respect to the axis of rotation, the impeller 70 has a thickness t, and H2 and t satisfy 0.2 ≦ H2 / t ≦ 0.6. Thus, the vortex flow 300 is prevented from becoming excessively flat in the second pump passage 206. In this structure, the energy of the vortex flow 300 of the second pump passage 206 is maintained, and the pump efficiency η 2 of the second pump passage 206 is improved. The fuel pressure after passing through the second pump passage 206 is lower than the fuel pressure after passing through the first pump passage 202. Therefore, it is desirable to improve the pump efficiency by satisfying 0.2? H2 / t? 0.6.

The first pump passage 202 has a depth H1 with respect to the rotation axis direction of the impeller 70. The impeller 70 has a thickness t. H1 and t satisfy 0.3 ≦ H1 / t ≦ 0.6, so that the vortex flow 300 of the first pump passage 202 is prevented from becoming excessively flat. In this structure, the energy of the vortex flow 300 of the first pump passage 202 is maintained, and the pump efficiency η of the first pump passage 202 is improved.

Two times the respective depth H1, H2 values of the respective pump passages 202, 206 are substantially equal to the respective widths W1, W2 of the respective pump passages 202, 206 with respect to the radial direction of the impeller 70, respectively. To satisfy the fact that the vortex flow 300 is substantially circular. That is, equations (9) and (10) satisfy the fact that the vortex flow 300 is formed in a substantially circular shape. Indeed, when W / H is within a predetermined range of two, the vortex flow 300 is not excessively flat.

2 x H1 = W1

2 × H2 = W2

2 = W1 / H1 (9)

2 = W2 / H2 (10)

The second pump passage 206 has a width W2 with respect to the radial direction of the impeller 70, the second pump passage 206 has a depth H2 with respect to the axis of rotation, and W2 and H2 have 1.9 ≦ W2 / H2 ≦ 2.5. Satisfies. Thus, the vortex flow 300 is prevented from becoming excessively flat. In this structure, the energy of the vortex flow 300 of the second pump passage is maintained, and the pump efficiency η of the second pump passage is improved. The fuel pressure pressurized through the second pump passage 206 is lower than the fuel pressure pressurized through the first pump passage 202. Therefore, it is preferable to improve the pump efficiency η by satisfying the relationship of 1.9 ≦ W2 / H2 ≦ 2.5.

The first pump passage 202 has a width W1 with respect to the direction of rotation of the impeller 70, the first pump passage 202 has a depth H1 with respect to the axis of rotation, and W1 and H1 have 1.5 ≦ W1 / H1 ≦ 2.1 Satisfies. Thus, the vortex flow 300 is prevented from becoming excessively flat. In this structure, the energy of the vortex flow 300 of the first pump passage 202 is maintained, and the pump efficiency η of the first pump passage 202 is improved.

(2nd Example)

6 to 8 show a fuel supply apparatus having a fuel pump according to the second embodiment. In this embodiment, referring to FIG. 6, the first pump passage 302 has a first cross-sectional area S1 indicated by a dashed line, and the second pump passage 306 has a second cross-sectional area S2 indicated by a dashed line. Has A seal portion having a seal width a1 is formed between the first cross-sectional area S1 and the second cross-sectional area S2. The impeller 51 has the rotation axis O. As shown in FIG.

The pump efficiency η is defined as η = (P × Q) / (T × R). Where T is the torque provided by the motor portion of the fuel pump, R is the rotational speed of the motor portion, P is the discharge pressure of the fuel after passing through the pump passage, and Q is the amount of discharged fuel after passing through the pump passage. to be. Referring to Fig. 9, the solid line indicates the relationship between the pump efficiency η and the seal width a1. The fuel is discharged by the discharge amount Q1 after passing through the first pump passage 302, and discharged by the discharge amount Q2 after passing through the second pump passage 306. In Fig. 9, each dotted line indicates the relationship between the value of Q2 / Q1 and the seal width a1. The dotted line indicates the relationship between the value of Q2 / Q1 and the seal width a1 in the impeller 51 having diameters of φ20, φ30, φ40 and φ50.

In this embodiment, the pressure P1 of the fuel after passing through the first pump passage 302 is also 200 to 800 kPa. The pressure P2 of the fuel after passing through the second pump passage 306 is also 50 kPa or less. That is, the fuel pressure P1 is higher than the fuel pressure P2. In such a structure, fuel leaks from the first pump passage 302 to the second pump passage 306, so that the pump efficiency η decreases. This fuel leakage is reduced with an increase in the seal width a1. When seal width a1 is 1 mm or more, pump efficiency (eta) 1 is 40% or more, and sufficient pump efficiency (eta) 1 is obtained. On the other hand, when the seal width a1 is smaller than 1 mm, fuel leaks from the first pump passage 302 to the second pump passage 306, so that the pump efficiency η 1 decreases rapidly. In contrast, if the seal width a1 is 2.5 mm or more, the pump efficiency η1 is substantially constant and does not increase further.

In addition, when the seal width a1 is excessively large, the second cross-sectional area S2 of the second pump passage 306 is not sufficiently guaranteed, and the relationship Q2 ≧ Q1 is not satisfied. If the value of Q2 / Q1 is 1 or more, the relationship of Q2≥Q1 is satisfied. To satisfy the relationship of Q2≥Q1, the seal width a1 is set to 8.5 mm or less when the impeller 51 has a diameter of φ50, and the seal width a1 is 2.5 mm or less when the impeller 51 has a diameter of φ30. Is set to. The diameter of 30 is a common value. In this regard, the optimum range of the seal width a1 mm is determined by the following equation (13).

1 ≤ a1 ≤ 2.5 (13)

As shown in Figs. 7 and 8, in this embodiment, each vane plate forming the radially outer vane groove 52a has a thickness B1, and each vane plate of the radially inner side has a thickness B2. Have Thickness B1 and thickness B2 satisfy the relationship of B2≥B1.

When there is fuel, the vane plate of the radially inner impeller 51 is expanded at expansion speed V2, and the vane plate of the radially outer impeller 51 is expanded at expansion speed V1. The expansion rate V2 and the expansion rate V1 have an expansion rate ratio V2 / V1. When the surface area of the impeller 51 becomes large, the expansion speed of the vane plate of the impeller 51 becomes large, and the thickness of the vane plate becomes small. The thickness B1 of the vane groove 52a on the radially outer side and the thickness B2 of the vane groove 52a on the radially inner side have a thickness ratio B2 / B1. In Fig. 10, the solid line shows the relationship between the expansion rate ratio V2 / V1 and the thickness ratio B2 / B1. When the expansion speed ratio V2 / V1 is equal to or greater than 1, that is, when the expansion speed V2 is equal to or larger than the expansion speed V1, the radially inner impeller 51 has a predetermined gap based on the radially outer impeller 51. It requires a larger gap. Therefore, it is preferable that expansion rate ratio V2 / V1 is 1 or less. When expansion rate ratio V2 / V1 is 1, thickness ratio B2 / B1 is 1.5.

In Fig. 10, the dotted line shows the relationship between the value Q2 / Q1 and the thickness ratio B2 / B1. As the thicknesses B1 and B2 of the vane plate increase, the expansion speed is lowered. Nevertheless, the second cross-sectional area S2 of the second pump passage 306 in Fig. 6 is not sufficiently guaranteed, and the relationship of Q2≥Q1 is Not satisfied The thickness ratio B2 / B1 is 3 or less to satisfy the relationship of Q2 ≧ Q1. Therefore, the range of thickness ratio B2 / B1 which satisfies the expansion rate and the fuel amount of the pump chamber is defined by the following equation (14).

1.5 ≤ (B2 / B1) ≤ 3 (14)

In this embodiment, the first pump passage and the second pump passage form a seal portion having a seal width a1 that satisfies 1 ≦ a1 ≦ 2.5 therebetween. The seal width a1 is determined to be 1 mm or more, so that fuel is prevented from leaking from the first pump passage 302 to the second pump passage 306. In addition, the quantity Q2 of fuel supplied from the fuel tank 2 to the sub tank 20 determines that the seal width a1 is 2.5 mm or less, so that the amount of fuel supplied from the sub tank 20 to the engine 500 is reduced. Excessively larger than the amount Q1 is prevented. Therefore, the pump efficiency η in the pump passage is improved.

The impeller 51 forms first vane grooves and has first vane plates each having a thickness B1. The impeller 51 forms second vane grooves and has second vane plates each having a thickness B2. B1 and B2 satisfy 1.5 ≦ B2 / B1 ≦ 3. As the thickness of each vane plate becomes smaller, the expansion rate increases. However, as the thickness of each vane plate becomes larger, the cross-sectional area of the pump passage becomes smaller accordingly, and as a result, the amount of fuel discharged from the fuel pump is reduced. Therefore, the value of B2 / B1 is set to 1.5 or more, and the expansion speed of each second vane plate is set to be equal to or less than the expansion speed of each first vane plate. Thus, the gap between the impeller 51 and the pump case is maintained, so that the impeller 51 and the pump case are limited in contact with each other. Further, the relationship of Q2≥Q1 is satisfied by setting the value of B2 / B1 to 3 or less. Therefore, the pump efficiency η is improved and the level of the sub tank 20 is maintained.

One pump passage may be formed on one side of the impeller with respect to the axis of rotation of the impeller.

In the first embodiment, the motor portion includes a brushless motor. Alternatively, the motor unit may include a motor having a brush.

The above structure of embodiments may be combined as appropriate.

Various modifications and variations of the embodiments can be made in various ways without departing from the spirit of the invention.

1 is a sectional view showing a pump passage of a fuel pump according to the first embodiment.

Fig. 2 is a sectional view showing the fuel supply device according to the first embodiment.

3 is a graph showing a relationship between a value Q2 / Q1 and a value (S2 × D2) / (S1 × D1).

4 is a graph showing the relationship between the value H / t and the pump efficiency η.

Fig. 5 is a graph showing the relationship between the value W / H and the pump efficiency η.

Fig. 6 is a sectional view showing the pump passage of the fuel pump according to the second embodiment.

7 is a sectional view showing a fuel supply device according to a second embodiment.

8 is a plan view showing an impeller;

9 is a graph showing the relationship between the seal width a1, the pump efficiency η, and the value Q2 / Q1.

10 is a graph showing the relationship between the thickness ratio B2 / B1, the expansion rate ratio V2 / V1, and the value Q2 / Q1.

<Explanation of symbols for main parts of the drawings>

2: fuel tank

10: fuel supply device

20: sub tank

30: fuel pump

36: housing

50, 52: pump case

70 impeller

74, 76: vane groove

202 and 302: first pump passage

206, 306: second pump passage

300: vortex flow

500: engine

Claims (11)

A fuel pump 30 which supplies fuel from the fuel tank 2 to the sub tank 20 accommodated in the fuel tank 2 and supplies fuel from the sub tank 20 to the engine 500, Impellers 70 and 51 having a plurality of first vane grooves 74 and a plurality of second vane grooves 76 arranged along the rotation direction thereof, A pump case (50, 52) rotatably receiving impellers (70, 51) and having first pump passages (202, 302) and second pump passages (206, 306) respectively formed along the rotational direction; , The plurality of second vane grooves 76 are located radially inward of the plurality of first vane grooves 74 with respect to the radial direction of the impellers 70 and 51, The first pump passages 202, 302 are formed along the first vane groove 74 to supply fuel from the sub tank 20 to the engine 500, and the second pump passages 206, 306 Is formed along the second vane groove 76 to supply fuel from the fuel tank 2 to the sub tank 20, The first and second pump passages 202, 206, 302, 306 each have a cross-sectional area S1, S2, The first and second pump passages 202, 206, 302, 306 have diameters D1, D2, respectively, with respect to the rotation axis direction of the impellers 70, 51, A fuel pump in which the cross-sectional areas S1 and S2 and the diameters D1 and D2 satisfy 0.6 ≦ (S2 × D2) / (S1 × D1) ≦ 0.95. 2. The fuel pump of claim 1, wherein the first pump passageway (202, 302) is configured to supply fuel at pressure P, and the pressure P satisfies 200 kPa <P <800 kPa. 2. The second pump passage 206, 306 has a depth H2 in the direction of the axis of rotation, Impellers 70 and 51 have a thickness t, And a depth H2 and a thickness t satisfy 0.2 &lt; H2 / t &lt; 0.6. 4. The first pump passage 202, 302 has a depth H1 relative to the axis of rotation, And a depth H1 and a thickness t satisfy 0.3 &lt; H1 / t &lt; 0.6. The second pump passage 206, 306 has a width W2 in the radial direction of the impellers 70, 51, according to claim 1. The second pump passages 206, 306 have a depth H 2 with respect to the axis of rotation, A fuel pump whose width W2 and depth H2 satisfy 1.9 ≦ W2 / H2 ≦ 2.5. The method of claim 5 wherein the first pump passages 202, 302 have a width W1 in the radial direction, The first pump passages 202, 302 have a depth H1 with respect to the axis of rotation, A fuel pump whose width W1 and depth H1 satisfy 1.5 ≦ W1 / H1 ≦ 2.1. The seal portion according to any one of claims 1 to 4, wherein a seal portion having a seal width a1 is formed between the first pump passages 202 and 302 and the second pump passages 206 and 306, A fuel pump in which the seal width a1 satisfies 1 ≤ a1 ≤ 2.5. The method according to any one of claims 1 to 4, The impellers 70, 51 form a plurality of first vane grooves 74 and each have a plurality of first vane plates having a thickness B1, The impellers 70, 51 form a plurality of second vane grooves 76 and each have a plurality of second vane plates having a thickness B2, A fuel pump in which thickness B1 and thickness B2 satisfy 1.5 ≦ B2 / B1 ≦ 3. The method according to any one of claims 1 to 4, A fuel pump further comprising a motor portion (32) for driving and rotating the impeller (70, 51). Fuel supply, The fuel pump 30 according to any one of claims 1 to 4, A sub tank 20 which receives the fuel pump 30 and is housed in the fuel tank 2; The first pump passages 202, 302 have an inlet 201 located inside the sub tank 20, The first pump passage 202, 302 has an outlet 203 for supplying fuel to the engine 500, The second pump passages 206, 306 have an inlet 205 located outside the sub tank 20 and open to the fuel tank 2, The second pump passage (206, 306) has an outlet (207) open to the sub tank (20). A fuel supply device for supplying fuel from the fuel tank 2 to the engine 500, A sub tank 20 accommodated in the fuel tank 2, A fuel pump 30 accommodated in the sub tank 20 to supply fuel from the fuel tank 2 to the sub tank 20 and at the same time supply the fuel from the sub tank 20 to the engine 500, The fuel pump 30, Impellers 70 and 51 having a plurality of first vane grooves 74 and a plurality of second vane grooves 76 arranged along the rotation direction thereof, A pump case (50, 52) having first and second pump passages (202, 206, 302, 306) rotatably receiving the impellers (70, 51), respectively, formed along the direction of rotation; The plurality of second vane grooves 76 are located radially inward of the plurality of first vane grooves 74, The first pump passage 202, 302 extends along the first vane groove 74, The first pump passages 202, 302 communicate with an inlet 201 located inside of the sub tank 20 to draw fuel and communicate with an outlet 203 to supply fuel to the engine 500. Become, The second pump passages 206, 306 extend along the second vane groove 76, The second pump passages 206, 306 are located outside the sub tank 20 and communicate with an inlet 205 which is open to the fuel tank 2 for drawing fuel from the fuel tank 2, and the sub tank ( In communication with an outlet 207 open to the sub tank for fueling 20), The first and second pump passages 202, 206, 302, 306 have cross sections S1, S2, respectively The first and second pump passages 202, 206, 302, 306 have diameters D1, D2, respectively, with respect to the rotation axis direction of the impellers 70, 51, A fuel supply apparatus in which the cross-sectional areas S1 and S2 and the diameters D1 and D2 satisfy 0.6 ≦ (S2 × D2) / (S1 × D1) ≦ 0.95.

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