JP2008163934A - Fuel pump and fuel feed apparatus using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel pump that supplies fuel to an internal combustion engine and a sub-tank from two rows of pump passages formed at radially shifted positions, to prevent excessive supply amount of fuel from the fuel tank to the sub-tank by taking into consideration the fuel discharge amount and fuel pressure of the pump passages, and to prevent lowering of an oil level of the sub-tank. <P>SOLUTION: Vane grooves 74, 76 are formed in two rows along a rotative direction. The pump passages 202, 206 are formed along the vane grooves 74, 76 in the rotative direction of an impeller 70. Fuel for the sub-tank is supplied from the pump passage 202 to the internal combustion engine, and fuel for a fuel tank is supplied from the pump passage 206 to the sub-tank. When passage areas of the pump passages 202, 206 are S1, S2, and diameters of the pump passages 202, 206 with the rotational axis of the impeller 70 as the center, are D1, D2, they are set as follows: 0.6≤(S2×D2)/(S1×D1)≤0.95. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention provides a fuel pump that forms two rows of blade grooves in the rotational direction at positions shifted in the radial direction of the impeller, supplies fuel from the subtank to the internal combustion engine, and supplies fuel from the fuel tank to the subtank, and uses the same The present invention relates to a fuel supply apparatus.

  There is known a fuel pump in which a fuel pump is housed in a sub-tank installed in the fuel tank, and the fuel in the sub-tank is boosted and supplied to an internal combustion engine. Among such fuel pumps, a fuel pump that does not use a jet pump and supplies fuel from a fuel tank to a sub tank by a fuel pump is known (see, for example, Patent Documents 1 and 2). In the fuel pumps of Patent Documents 1 and 2, two rows of blade grooves are formed in the rotational direction at positions displaced in the radial direction of the impeller, and the pump cases that rotatably accommodate the impellers along the two rows of blade grooves respectively. A pump passage is formed. Then, by rotation of the impeller, the fuel in the subtank is boosted in the pump passage along the blade groove on the outer peripheral side of the impeller and supplied to the internal combustion engine, and in the fuel tank in the pump passage along the blade groove on the inner peripheral side of the impeller. The fuel is boosted and supplied to the sub tank.

  Here, in such a fuel pump, if the fuel discharge amount supplied from the fuel pump to the internal combustion engine is Q1, and the fuel discharge amount supplied from the fuel pump to the sub-tank is Q2, the maximum required at the maximum output of the internal combustion engine Also in the fuel requirement amount, it is necessary to satisfy Q2 ≧ Q1. This is because Q2 <Q1, that is, the fuel discharge amount Q2 supplied from the fuel tank to the sub-tank becomes smaller than the fuel discharge amount Q1 supplied from the sub-tank to the internal combustion engine. This is because the pump cannot suck the fuel in the sub tank. Therefore, it is necessary to design a fuel pump having two rows of blade grooves and a pump passage so as to satisfy Q2 ≧ Q1 and prevent a decrease in the liquid level of the sub tank.

By the way, the fuel pressure that boosts the fuel in the sub tank and supplies it to the internal combustion engine is much higher than the fuel pressure that boosts the fuel in the fuel tank and supplies it to the sub tank. Therefore, the pressure difference in the rotation direction is larger in the pump passage for boosting the fuel in the sub tank and supplying the fuel to the internal combustion engine than in the pump passage for boosting the fuel in the fuel tank and supplying the fuel to the sub tank. When the pressure difference in the rotation direction of the pump passage is increased, a force is generated in the pump passage to cause the fuel to flow backward in the direction opposite to the rotation direction, so that the pump efficiency is reduced. Further, when the fuel pressure to be increased is high, the amount of fuel leaking from the clearance between the pump case and the impeller increases, so that the pump efficiency decreases. Therefore, it is necessary to design the fuel pump in consideration of not only the fuel discharge amount but also the fuel pressure for boosting the fuel in the pump passage. Here, assuming that the torque of the motor part of the fuel pump is T, the rotational speed of the motor part is R, the discharge pressure of the fuel discharged from the pump passage is P, and the fuel discharge amount is Q, (pump efficiency) = (P × Q) / (T × R).
However, although Patent Document 1 describes Q2> Q1, Patent Documents 1 and 2 describe a fuel pump that prevents a decrease in the liquid level of the sub tank in consideration of the fuel pressure in the pump passage. Absent.

US Pat. No. 5,596,970 Special Table 2002-500728

  The present invention has been made to solve the above-described problems, and supplies fuel to an internal combustion engine and a sub tank from two rows of pump passages formed at positions shifted in the radial direction. To provide a fuel pump and a fuel supply device using the same that prevent an excessive amount of fuel supply from a fuel tank to a sub tank in consideration of pressure and prevent a decrease in liquid level of the sub tank. With the goal.

Here, the fuel discharge amount of the first pump passage is Q1, the diameter of the first pump passage around the rotation shaft of the impeller is D1, the passage sectional area of the first pump passage is S1, and the first pump passage Q2 is the fuel discharge amount of the second pump passage formed on the inner peripheral side of the shaft, D2 is the diameter of the second pump passage around the rotation shaft of the impeller, and S2 is the cross-sectional area of the second pump passage. When the rotational speed per minute of the impeller is R, the fuel discharge amounts Q1 and Q2 per minute are expressed by the following equations (1) and (2). In the configuration in which the pump passage is formed on both sides of the impeller in the rotation axis direction, S1 and S2 are the sum of the passage areas of the pump passages on both sides of the impeller in the rotation axis direction.
Q1 = π × S1 × D1 × R (1)
Q2 = π × S2 × D2 × R (2)

Therefore, considering only the flow rate without considering the fuel pressure in the pump passage, even if fuel is supplied from the sub tank to the internal combustion engine, in order to prevent the liquid level of the sub tank from being lowered, if Q2 ≧ Q1 is satisfied. Good. That is, the following equation (3) may be satisfied.
Q2 ≧ Q1
π × S2 × D2 × R ≧ π × S1 × D1 × R
(S2 × D2) / (S1 × D1) ≧ 1 (3)

  However, since the first pump passage for supplying fuel from the sub tank to the internal combustion engine has a higher fuel pressure than the second pump passage for supplying fuel from the fuel tank to the sub tank, the pressure difference causes the first pump passage to be in a direction opposite to the rotation direction. The applied force and the fuel leakage are larger than those of the second pump passage. As a result, the decrease amount of the fuel discharge amount Q1 from the first pump passage equation (1) is larger than the decrease amount of the fuel discharge amount Q2 from the second pump passage equation (2). Therefore, if the passage areas and diameters of the first pump passage and the second pump passage are set so as to satisfy the expression (3), the actual Q2 becomes too larger than Q1. As a result, excess fuel is supplied from the fuel tank to the sub tank.

Therefore, in the inventions according to claims 1 to 9, in consideration of the fuel pressures of the first pump passage and the second pump passage, the passage areas and diameters of the first pump passage and the second pump passage are expressed by the formula ( It is set to satisfy 4).
0.6 ≦ (S2 × D2) / (S1 × D1) ≦ 0.95 (4)
By satisfying 0.6 ≦ (S2 × D2) / (S1 × D1), the fuel discharge amount Q2 supplied from the fuel tank to the sub-tank becomes smaller than the fuel discharge amount Q1 supplied from the sub-tank to the internal combustion engine. It can be prevented from passing. Further, by satisfying (S2 × D2) / (S1 × D1) ≦ 0.9, the fuel discharge amount Q2 supplied from the fuel tank to the sub tank is larger than the fuel discharge amount Q1 supplied from the sub tank to the internal combustion engine. It can prevent becoming too much. Thus, by setting the passage areas and diameters of the first pump passage and the second pump passage so as to satisfy the expression (4), in the invention according to claims 1 to 9, the fuel tank to the sub tank The fuel supply amount is prevented from becoming excessive, and the liquid level height of the sub tank is prevented from being lowered.

  In the second aspect of the invention, the fuel pressure P (kPa) discharged from the first pump passage is 200 ≦ P ≦ 800. By setting the passage areas and diameters of the first pump passage and the second pump passage so as to satisfy the expression (4) according to the value of the fuel pressure P satisfying this range, the fuel from the fuel tank to the sub tank is set. While preventing the supply amount from becoming excessive, it is possible to prevent the liquid level of the sub tank from being lowered.

By the way, as the impeller rotates, the fuel in the pump passage repeatedly enters and exits the blade groove from the blade groove at the front in the rotation direction toward the blade groove at the rear in the rotation direction, and is boosted as a swirl flow. The swirling flow desirably has a flow shape close to a circle in the cross section of the swirling passage including the pump passage and the blade groove. This is to prevent the direction of the swirling flow from changing suddenly when swirling and reducing the swirling flow energy as much as possible. By preventing a decrease in the energy of the swirling flow, the pump efficiency in the pump passage is increased. In order for the flow shape of the swirling flow to be a circle, the depth of the pump passage and the depth of the blade groove should be substantially equal in the thickness direction of the impeller. The depth H in the impeller rotation axis direction of the blade groove corresponds to approximately ½ of the impeller plate thickness t, and therefore, the following equation (5) may be satisfied. Actually, the value of H / t should be set within a predetermined range including 0.5, and the flow shape of the swirling flow should not be too flat.
H = t / 2
H / t = 0.5 (5)

  Therefore, in the third aspect of the invention, if the depth of the second pump passage in the direction of the impeller rotating shaft is H2, and the thickness of the impeller is t, 0.2 ≦ H2 / t ≦ 0.6 is set. In the second pump passage, the flow shape of the swirling flow is prevented from becoming too flat. Thereby, since the fall of the energy of the swirl | vortex flow in a 2nd pump channel | path can be prevented, the pump efficiency in a 2nd pump channel | path rises. In the second pump passage, since the fuel pressure to be increased is lower than that in the first pump passage, it is desirable to satisfy 0.2 ≦ H2 / t ≦ 0.6 and increase the pump efficiency.

  In the invention according to claim 4, when the depth of the first pump passage in the direction of the impeller rotating shaft is H1, and the thickness of the impeller is t, 0.3 ≦ H1 / t ≦ 0.6 is set. The flow shape of the swirling flow is prevented from becoming too flat in one pump passage. Thereby, since the fall of the energy of the swirl | vortex flow in a 1st pump channel | path can be prevented, the pump efficiency in a 1st pump channel | path rises.

Further, in order for the flow shape of the swirling flow to be a circle, twice the depth H of the pump passage and the radial width W of the pump passage may be substantially equal. That is, the following equation (6) may be satisfied. Actually, the value of W / H should be set to a predetermined range including 2, and the shape of the swirling flow should not be too flat.
2 x H = W
2 = W / H (6)

  Therefore, in the invention described in claim 5, when the radial width of the second pump passage is W2 and the depth of the second pump passage is H2, 1.9 ≦ W2 / H2 ≦ 2.5 is set. In addition, the cross-sectional shape of the swirling flow is prevented from becoming too flat. Thereby, since the fall of the energy of the swirl | vortex flow in a 2nd pump channel | path can be prevented, the pump efficiency in a 2nd pump channel | path rises. In the second pump passage, the fuel pressure to be increased is lower than that in the first pump passage. Therefore, it is desirable to satisfy 1.9 ≦ W2 / H2 ≦ 2.5 to increase the pump efficiency.

  In the invention according to claim 6, assuming that the width of the first pump passage in the radial direction is W1 and the depth of the first pump passage in the direction of the impeller rotating shaft is H1, 1.5 ≦ W1 / H1 ≦ 2. 1 is set to prevent the flow shape of the swirling flow in the first pump passage from becoming too flat. Thereby, since the fall of the energy of the swirl | vortex flow in a 1st pump channel | path can be prevented, the pump efficiency in a 1st pump channel | path rises.

  In the seventh aspect of the invention, the seal width a (mm) of the seal portion provided between the first pump passage and the second pump passage is set to 1 ≦ a ≦ 2.5. By setting the seal width a to 1 mm or more, fuel leakage from the first pump passage to the second pump passage can be prevented. By setting the seal width a to 2.5 mm or less, it is possible to prevent the fuel discharge amount Q2 supplied from the fuel tank to the sub tank from being excessively larger than the fuel discharge amount Q1 supplied from the sub tank to the internal combustion engine. As a result, the pump efficiency in the pump passage increases.

  In the invention according to claim 8, the plate width of the plurality of first blades provided on the outer peripheral side of the impeller is B1, and the plate width of the plurality of second blades provided on the inner peripheral side of the impeller is B2. Then, 1.5 ≦ B2 / B1 ≦ 3 is set. The thinner the impeller blades, the faster the swelling speed. On the other hand, if the blade width of the impeller blades is thick, the passage cross-sectional area of the pump passage is reduced accordingly, and the fuel discharge amount is reduced. Therefore, B2 / B1 is set to 1.5 or more, and the swelling speed of the impeller second blade is the same as or slower than the swelling speed of the impeller first blade. Clearance can be narrowed to prevent contact. Further, by setting B2 / B1 to 3 or less, Q2 ≧ Q1 can be satisfied. As a result, the pump efficiency is increased, and the lowering of the liquid level of the sub tank is prevented.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
A fuel supply apparatus using a fuel pump according to the first embodiment of the present invention is shown in FIG. In FIG. 2, a thick arrow indicates the direction of fuel flow. The fuel supply device 10 is installed in the fuel tank 2 in a state where the fuel pump 30 is accommodated in the sub tank 20. The fuel pump 30 is an in-tank type turbine pump mounted on, for example, a two-wheeled vehicle or a four-wheeled vehicle.

The sub tank 20 is formed in a bottomed cylindrical shape or rectangular box shape by resin. The bottom wall 22 of the sub tank 20 is formed with a leg portion 23 that protrudes toward the bottom wall 3 of the fuel tank 2 and contacts the bottom wall 3. The leg portion 23 forms a space 210 between the bottom wall 22 of the sub tank 20 and the bottom wall 3 of the fuel tank 2.
The fuel pump 30 includes a motor unit 32 and a pump unit 34 that is rotationally driven by the motor unit 32. The housing 36 also serves as a housing for the motor portion 32 and the pump portion 34, and the end cover 38 and the pump case 50 are caulked at both ends in the axial direction. The end cover 38 is made of resin. The end cover 38 is formed with a discharge port 39 for supplying fuel boosted by the fuel pump 30 to an internal combustion engine (not shown).

The motor unit 32 is a direct current brush motor including a permanent magnet, a commutator, a brush, a choke coil, an armature 40, and the like (not shown). The permanent magnet is formed in an arc shape, and a plurality of permanent magnets are attached to the inner peripheral wall of the housing 36 in the circumferential direction.
The armature 40 is rotatably installed on the inner peripheral side of the permanent magnet. The shaft 42 of the armature 40 is rotatably supported at both ends in the axial direction by metal bearings 44 (in FIG. 2, only the bearing 44 at one end in the axial direction is shown). The bearing 44 is supported by the pump case 52. The armature 40 includes a rotor core that forms a plurality of magnetic pole cores in the rotation direction, and coils that are wound around the magnetic pole cores. A drive current is supplied to the coil of the armature 40 through a brush and a commutator.

  The pump unit 34 is a turbine pump having pump cases 50 and 52 and an impeller 70. The pump part 34 is installed on one side of the armature 40 in the rotation axis direction with respect to the motor part 32. The pump cases 50 and 52 are case members that rotatably accommodate the impeller 70, and are formed of a metal material such as aluminum or a high-strength resin material that has excellent fuel resistance. The pump case 50 covers the sub tank 20 side of the pump unit 34, and the pump case 52 covers the armature 40 side of the pump unit 34.

  The impeller 70 is formed in a disk shape with a high strength resin material having excellent fuel resistance. As shown in FIG. 1, the outer periphery of the impeller 70 is surrounded by an annular portion 72, and a plurality of blade grooves 74 as first blade grooves rotate on the outer peripheral edge portion of the impeller 70 on the inner peripheral side of the annular portion 72. Is formed in the direction. On the inner peripheral side of the blade groove 74, a plurality of blade grooves 76 serving as second blade grooves are formed in the rotational direction so as to be displaced in the radial direction from the first blade groove 74. The blade grooves 74 and 76 are formed on both sides of the impeller 70 in the rotation axis direction. The blade grooves 74 and 76 formed on both sides in the rotation axis direction communicate with each other. The fuel flowing into the blade grooves 74 and 76 flows as the swirl flow 300 in the blade grooves 74 and 76 on both sides in the rotation axis direction. The blade grooves 74 and 76 adjacent to each other in the rotation direction are partitioned by partition walls 75 and 77, respectively.

The pump passages 202 and 206 are formed in a C shape in the pump cases 50 and 52 on both sides in the rotation axis direction of the impeller 70 along the blade grooves 74 and 76 in the rotation direction of the impeller 70. A pump passage 202 as a first pump passage communicates with the blade groove 74, and a pump passage 206 as a second pump passage communicates with the blade groove 76.
As shown in FIG. 2, the fuel inlet 201 of the pump passage 202 is formed in the pump case 50, and the fuel outlet 203 of the pump passage 202 is formed in the pump case 52. The fuel inlet 201 opens toward the sub tank 20, and the fuel outlet 203 of the pump passage 202 opens toward the fuel chamber 208 in the motor unit 32. A suction filter 60 for removing foreign matters in the fuel in the sub tank 20 is attached to the fuel inlet 201.

  A fuel inlet 205 and a fuel outlet 207 of the pump passage 206 are formed in the pump case 50. The fuel inlet 205 passes through the bottom wall 22 of the sub tank 20 and opens toward the outside of the sub tank 20 and the inside of the fuel tank 2, and the fuel outlet 207 opens toward the inside of the sub tank 20. Between the bottom wall 22 of the sub tank 20 and the fuel inlet 205 where the fuel inlet 205 penetrates, an elastic member 64 formed in a cylindrical shape with rubber or the like is installed as a sealing material. The elastic member 64 prevents fuel from leaking from the bottom wall 22 where the fuel inlet 205 penetrates. The fuel inlet 205 is provided with a check valve 66 that prevents the backflow of fuel from the sub tank 20 to the fuel tank 2. Since the check valve 66 is installed at the fuel inlet 205, the fuel in the fuel pump 30 is prevented from flowing into the fuel tank 2 when the fuel pump 30 is stopped, and the fuel is injected into the fuel pump 30. Can be stored. As a result, when the fuel pump 30 is started, the fuel can be quickly sucked from the fuel inlet 205 and the fuel in the fuel tank 2 can be supplied to the sub tank 20. Further, a suction filter 62 for removing foreign matters in the fuel in the fuel tank 2 is attached to the fuel inlet 205. The suction filter 62 is installed in a space 210 formed between the bottom wall 22 of the sub tank 20 and the bottom wall 3 of the fuel tank 2.

  In FIG. 2, when the impeller 70 rotates together with the shaft 42 by the rotation of the armature 40, the fuel sucked into the pump passages 202 and 206 from the fuel inlets 201 and 205, respectively, from the vane grooves 74 and 76 in the rotation direction forward. By repeating many outflows and inflows toward the rear blade grooves 74 and 76, the swirl flow 300 is increased in pressure by the pump passages 202 and 206.

  The fuel in the sub-tank 20 sucked from the fuel inlet 201 by the rotation of the impeller 70 is boosted in the pump passages 202 on both sides in the rotation axis direction, and merged at the fuel outlet 203 formed in the pump case 52 on the motor unit 32 side. The fuel is discharged from the outlet 203 into the fuel chamber 208 of the motor unit 32. The fuel discharged from the fuel outlet 203 into the fuel chamber 208 passes through a gap formed between the outer peripheral surface of the armature 40 and the inner peripheral surface of a permanent magnet (not shown), and the discharge port 39 provided in the end cover 38. To the internal combustion engine side. Thus, since the fuel pressurized by the pump unit 34 flows inside the motor unit 32, the fuel cools the motor unit 32 and lubricates the sliding part inside the motor unit 32.

The fuel discharge amount discharged from the discharge port 39 and supplied to the internal combustion engine is 20 L / h to 300 L / h. This fuel discharge amount corresponds to the fuel discharge amount discharged from the fuel outlet 203 of the pump passage 202. The rotation speed of the impeller 70 is 4000-15000 rpm.
Further, the fuel in the fuel tank 2 sucked from the fuel inlet 205 by the rotation of the impeller 70 is boosted in the pump passages 206 on both sides in the rotation axis direction, and merges at the fuel outlet 207 formed in the pump case 50, and the fuel outlet 207 To the sub tank 20.

Next, design values of the impeller 70 and the pump passages 202 and 206 will be described.
The outer diameter of the impeller 70 is set in the range of 20 mm to 50 mm. One passage cross-sectional area S1 and S2 of the pump passages 202 and 206 formed on both sides in the rotational axis direction along the blade grooves 74 and 76 is set in a range of ² mm ^{2 to} 8 mm ² . The discharge amount of the pump passage 202 is Q1, the diameter of the pump passage 202 around the rotation shaft of the impeller 70 is D1, the discharge amount of the pump passage 206 is Q2, and the discharge amount of the pump passage 206 around the rotation shaft of the impeller 70 is Assuming that the diameter is D2 and the rotation speed per minute of the impeller 70 is R, Q1 and Q2 are expressed by the equations (1) and (2) as described above. However, in the formulas (1) and (2), S1 is replaced with 2 × S1, and S2 is replaced with 2 × S2. The diameters D1 and D2 represent the distance between the centers 100 of the radial passage width W1 of the pump passage 202 and the distance between the centers 102 of the radial passage width W2 of the pump passage 206.
Here, even if fuel is supplied from the sub tank 20 to the internal combustion engine outside the fuel tank 2, in order to prevent the liquid level of the sub tank 20 from being lowered, Q2 ≧ Q1 should be satisfied. That is, the expression (3) should be satisfied.

  However, the fuel pressure increased in the pump passage 202 is higher than the fuel pressure increased in the pump passage 206. For example, the required value of the fuel pressure P1 that is boosted in the pump passage 202 and supplied from the fuel pump 30 to the internal combustion engine is in the range of 200 kPa to 800 kPa, and is boosted in the pump passage 206 and supplied from the fuel pump 30 into the sub tank 20. The required fuel pressure P2 is about 50 kPa at the maximum. As a result, in the pump passage 202, the force acting in the direction opposite to the rotational direction due to the fuel pressure difference in the rotational direction, and the amount of fuel leaking from the clearance between the impeller 70 and the pump cases 50, 52 are larger than in the pump passage 206. Therefore, the amount of decrease from the fuel discharge amount Q1 expressed by the equation (1) of the pump passage 202 is larger than the amount of decrease from the fuel discharge amount Q2 expressed by the equation (2) of the pump passage 206. Therefore, if the passage areas and diameters of the pump passage 202 and the pump passage 206 are set so as to satisfy the expression (3), the actual Q2 becomes too larger than Q1. As a result, the amount of fuel supplied from the fuel tank 2 to the sub tank 20 becomes excessive. The sub tank 20 only needs to be supplied with an amount of fuel that does not lower the liquid level of the sub tank 20, and it is not necessary to supply an excessive amount of fuel from the fuel tank 2 to the sub tank 20.

Therefore, it is necessary to set the range of (S2 × D2) / (S1 × D1) in consideration of the range of the fuel pressure P1 that is increased in the pump passage 202. As described above, the range of the fuel pressure P1 boosted in the pump passage 202 and supplied from the fuel pump 30 to the internal combustion engine is in the range of 200 kPa to 800 kPa. Therefore, it is required to set the range of (S2 × D2) / (S1 × D1) so that the actual value of Q2 / Q1 approaches 1 as much as possible in the range of 200 kPa to 800 kPa. Therefore, the range of the following equation (7) is obtained from FIG.
0.6 ≦ (S2 × D2) / (S1 × D1) ≦ 0.95 (7)
If it is the range of Formula (7), (S2 * D2) / (S1 * D1) can be set so that the actual value of Q2 / Q1 may approach 1 as much as possible in the range where the fuel pressure P1 is 200 kPa to 800 kPa.

  The flow shape of the swirling flow 300 flowing through the pump passage 202 and the blade groove 74 and between the pump passage 206 and the blade groove 76 is preferably close to a circle. This is to prevent the direction of the swirl flow 300 from changing suddenly when swirling and to reduce the energy of the swirl flow 300 as much as possible, and to increase the pump efficiency η.

In order for the flow shape of the swirling flow 300 to be a circle, the depths H1 and H2 of the pump passages 202 and 206 in the impeller rotation axis direction and the depths of the blade grooves 74 and 76 are substantially equal in the plate thickness direction of the impeller 70. It only has to be. Since the depths H1 and H2 of the pump passages 202 and 206 correspond to approximately half of the plate thickness t of the impeller, the equations (8) and (9) may be satisfied.
H1 / t = 0.5 (8)
H2 / t = 0.5 (9)

Actually, the values of H1 / t and H2 / t may be set to a predetermined range including 0.5, and the flow shape of the swirling flow 300 may not be too flat. Therefore, from FIG. 4, H1 / t and H2 / t satisfying η1 ≧ 40% and η2 ≧ 10% are obtained as a predetermined range in which the pump efficiency η1 and η2 in the pump passages 202 and 206 include the maximum values. Expressions (10) and (11) are obtained.
0.3 ≦ H1 / t ≦ 0.6 (10)
0.2 ≦ H2 / t ≦ 0.6 (11)
Since the pump efficiency of the pump passage 206 is lower than that of the pump passage 202, it is particularly desirable to satisfy the equation (11).

In addition, in order for the flow shape of the swirl flow 300 to be a circle, the depths H1 and H2 of the pump passages 202 and 206 and the radial widths W1 and W2 of the pump passages 202 and 206 are almost equal. Good. That is, the expressions (12) and (13) may be satisfied.
2 = W1 / H1 (12)
2 = W2 / H2 (13)

Actually, the values of W1 / H1 and W2 / H2 are set to a predetermined range including 2, and the flow shape of the swirling flow 300 may not be too flat. Therefore, from FIG. 5, when W1 / H1 and W2 / H2 satisfying η1 ≧ 40% and η2 ≧ 10% are obtained as a predetermined range in which the pump efficiency η1 and η2 in the pump passages 202 and 206 include the maximum values, Equations (14) and (15) are obtained.
1.5 ≦ W1 / H1 ≦ 2.1 (14)
1.9 ≦ W2 / H2 ≦ 2.5 (15)
Since the pump efficiency of the pump passage 206 is lower than that of the pump passage 206, it is particularly desirable to satisfy the equation (15).

  As described above, in the present embodiment, the fuel pump 30 in which the blade grooves 74 and 76 are formed at positions shifted in the radial direction of the impeller 70 supplies the fuel in the sub tank 20 to the internal combustion engine, and the fuel tank. Two fuels are supplied to the sub tank 20. In the fuel pump 30 having such a configuration, the passage areas S1 and S2 of the pump passages 202 and 206 and the rotating shaft of the impeller 70 are taken into consideration, particularly in consideration of the fuel pressure of the pump passage 202 that boosts the fuel supplied to the internal combustion engine. (S2 × D2) / (S1 × D1) is set to an appropriate range shown in Expression (7) with respect to the diameters D1 and D2 of the pump passages 202 and 206. Thereby, it is possible to prevent the liquid level of the sub tank 20 from being lowered and to prevent the amount of fuel supplied from the fuel tank 2 to the sub tank 20 from becoming excessive.

  Further, with respect to the depths H1 and H2 of the pump passages 202 and 206 and the plate thickness t of the impeller 70, H1 / t and H2 / t are set within appropriate ranges shown in the equations (10) and (11). In addition, for the depths H1 and H2 of the pump passages 202 and 206 and the radial widths W1 and W2 of the pump passages 202 and 206, W1 / H1 and W2 / H2 are in appropriate ranges shown in the equations (14) and (15). Is set. Thereby, the flow shape of the swirling flow 300 flowing through the pump passage 202 and the blade groove 74 and between the pump passage 206 and the blade groove 76 is prevented from being flattened, and the pump efficiency is increased.

(Second embodiment)
A fuel supply device using a fuel pump according to a second embodiment of the present invention is shown in FIGS. Components that are substantially the same as those of the first embodiment are denoted by the same reference numerals and description thereof is omitted. In the present embodiment, as shown in FIG. 6, the seal width a of the seal portion is between the second pump passage sectional area S <b> 2 and the first pump passage sectional area S <b> 1 indicated by the dashed line and the two-dot chain line. The seal width of the seal part provided in is shown. O indicates the center line of the impeller 51.

  FIG. 9 is a characteristic diagram showing the relationship between the seal width a of the seal portion, the pump efficiency, and the internal / external flow rate ratio according to the second embodiment of the present invention. When the torque of the motor part of the fuel pump is T, the rotational speed of the motor part is R, the discharge pressure of the fuel discharged from the pump passage is P, and the fuel discharge amount is Q, the pump efficiency is (pump efficiency) = (P * Q) / (T * R). The solid line shows the relationship between the pump efficiency and the seal width a. The dotted line represents the relationship between the value obtained by dividing the fuel discharge amount Q2 of the second pump passage by the fuel discharge amount Q1 of the first pump passage and the seal width a, and the impeller diameter (mm) is φ20, Measurement was performed on four types of φ30, φ40, and φ50.

  Also in this embodiment, the fuel pressure P discharged from the first pump passage is 200 to 800 kPa, which is higher than the fuel pressure discharged from the second pump passage is 50 kPa or less. For this reason, fuel leakage occurs from the first pump passage on the high pressure side to the second pump passage on the low pressure side, and the pump efficiency decreases. This fuel leakage can be reduced by increasing the seal width a. When the seal width a is 1 mm or more, the pump efficiency is a sufficient value of 40% or more, and when the seal width a is 1 mm or less, the pump efficiency is drastically reduced and the second pressure on the low pressure side from the first pump passage is reduced. Fuel leakage will occur in the pump passage. When the seal width a is 2.5 mm or more, the pump efficiency becomes constant and does not improve any more.

On the other hand, if the seal width a is too large, the inner passage cross-sectional area (S2 in FIG. 6) cannot be secured sufficiently, so that Q2 ≧ Q1 is not satisfied. In order to satisfy Q2 ≧ Q1, Q2 / Q1 is 1 or more. The relationship that satisfies this relationship is that the impeller diameter φ50 has a seal width a of 8.5 mm or less, and the general impeller diameter φ30 has a seal width a of 2.5 mm or less. From the above, the optimum seal width a (mm) was set as the following equation (16).
1 ≦ a ≦ 2.5 (16)

  FIG. 7 is a cross-sectional view showing the fuel supply device of this embodiment, and FIG. 8 is a plan view of the impeller taken along the line XX in FIG. In the present embodiment, if the plate width of the blades of the outer impeller divided by the blade grooves 52a of the impeller 51 is B1, and the plate width of the blades of the inner impeller is B2, B2 ≧ B1 is set.

  FIG. 10 is a characteristic diagram showing the relationship between the plate width ratio, the swelling speed, and Q2 / Q1 of the impeller blade according to the second embodiment of the present invention. The impeller blade swelling speed increases as the surface area of the impeller increases and the plate thickness decreases. The solid line indicates the relationship between the value obtained by dividing the inner impeller blade swelling speed by the outer impeller blade swelling speed and the blade width ratio (B2 / B1). If the value obtained by dividing the inner impeller blade swelling speed by the outer impeller blade swelling speed is 1 or more, that is, the inner impeller blade swelling speed is larger than the outer impeller blade swelling speed, the clearance is wider than the clearance set based on the outer impeller blade. Is required. Therefore, the value obtained by dividing the inner impeller blade swelling speed by the outer impeller blade swelling speed is preferably 1 or less, and the blade width ratio at that time is 1.5.

The dotted line shows the relationship between the value of Q2 / Q1 and the blade width ratio (B2 / B1) of the blades. When the blade width is increased, the swelling speed is decreased, but the inner passage cross-sectional area (S2 in FIG. 6) cannot be secured sufficiently, so that Q2 ≧ Q1 is not satisfied. The blade width ratio of Q2 ≧ Q1 is 3 or less. Therefore, the blade width ratio satisfying the swelling speed and the pump chamber flow rate was set as the following equation (17).
1.5 ≦ (B2 / B1) ≦ 3 (17)

(Third embodiment)
In the third embodiment, pump passages are formed on both sides of the impeller in the rotation axis direction. In the present invention, the pump passage may be formed only on one side of the impeller in the rotation axis direction.
In the first embodiment, a brush motor is employed for the motor unit. In the present invention, a brushless motor may be employed for the motor portion of the fuel pump.

  As described above, the present invention is not limited to the above-described embodiment, and can be applied to various embodiments without departing from the gist thereof.

A sectional view showing a pump passage of a first embodiment. Sectional drawing which shows the fuel supply apparatus of 1st embodiment. The characteristic view which shows the relationship between (S2 * D2) / (S1 * D1) and (Q2 / Q1). The characteristic view which shows the relationship between (H / t) and pump efficiency (eta). The characteristic view which shows the relationship between (W / H) and pump efficiency (eta). Sectional drawing which shows the principal part of the fuel supply apparatus of 2nd embodiment. Sectional drawing which shows the fuel supply apparatus of 2nd embodiment. Impeller top view of the second embodiment The characteristic view which shows the relationship between the seal width a of 2nd embodiment, pump efficiency (eta), (Q2 / Q1). The characteristic view which shows the relationship between impeller board thickness ratio (B2 / B1) of 2nd embodiment, swelling speed, and (Q2 / Q1).

Explanation of symbols

DESCRIPTION OF SYMBOLS 10: Fuel supply apparatus, 20: Sub tank, 30: Fuel pump, 32: Motor part, 34: Pump part, 40: Armature, 42: Shaft (rotary shaft), 50, 52: Pump case, 51, 70: Impeller , 52a, 74, 76: vane groove, 202, 206: pump passage

Claims (9)

In a fuel pump for supplying fuel in the fuel tank to a sub-tank installed in the fuel tank and supplying fuel in the sub-tank to an internal combustion engine,
An impeller that is rotationally driven by the motor unit and has a plurality of first blade grooves on the outer peripheral side and a plurality of second blade grooves on the inner peripheral side of the first blade grooves;
The impeller is rotatably accommodated, is formed in a rotation direction along the first blade groove, and is provided in a first pump passage for supplying fuel in the sub tank to the internal combustion engine, and in the second blade groove. A pump case having a second pump passage formed in a rotational direction along the direction of supplying fuel in the fuel tank into the sub-tank;
With
The cross-sectional area of the first pump passage is S1, the diameter of the first pump passage around the rotation axis of the impeller is D1, the cross-sectional area of the second pump passage is S2, and the rotation of the impeller A fuel pump characterized in that 0.6 ≦ (S2 × D2) / (S1 × D1) ≦ 0.95, where D2 is a diameter of the second pump passage centered on the shaft.   2. The fuel pump according to claim 1, wherein the fuel pressure P (kPa) discharged from the first pump passage satisfies 200 ≦ P ≦ 800.   The depth of the second pump passage in the impeller rotation axis direction is H2, and the thickness of the impeller is t, and 0.2≤H2 / t≤0.6. The fuel pump described in 1.   4. The fuel pump according to claim 3, wherein 0.3 ≦ H1 / t ≦ 0.6, where H <b> 1 is a depth of the first pump passage in an impeller rotation axis direction.   1.9 ≦ W2 / H2 ≦ 2.5, where W2 is the radial width of the second pump passage and H2 is the depth of the second pump passage in the impeller rotation axis direction. The fuel pump according to any one of claims 1 to 4.   When the width in the radial direction of the first pump passage is W1 and the depth of the first pump passage in the impeller rotation axis direction is H1, 1.5 ≦ W1 / H1 ≦ 2.1. The fuel pump according to claim 5.   2. If the seal width of a seal portion provided between the first pump passage and the second pump passage is a (mm), 1 ≦ a ≦ 2.5. 7. The fuel pump according to 6.   When the plate width of the plurality of first blades provided on the outer peripheral side of the impeller is B1, and the plate width of the plurality of second blades provided on the inner peripheral side of the impeller is B2, 1.5 ≦ 8. The fuel pump according to claim 1, wherein B2 / B1 ≦ 3. A fuel pump according to any one of claims 1 to 8,
A sub tank that houses the fuel pump and is installed in the fuel tank;
With
The fuel inlet of the first pump passage opens into the sub tank, and the fuel discharged from the fuel outlet of the first pump passage is supplied to the internal combustion engine,
The fuel supply device according to claim 1, wherein a fuel inlet of the second pump passage opens to the outside of the sub tank and the inside of the fuel tank, and a fuel outlet of the second pump passage opens to the inside of the sub tank.

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