JP2007255405A - Fuel pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel pump with increased pump efficiency. <P>SOLUTION: In a disk-like impeller 30, vane grooves 36 are formed in the rotating direction, and an annular peripheral part surrounding the vane groove 36 is formed on the outside of the vane grooves. Fuel sucked from a fuel inlet formed in a pump cover 20 is boosted by the rotation of the impeller 30 in pressure boosting passages 202, 203 on both sides of the impeller 30 in the thickness direction, and force-fed from a discharge port formed in a pump cover 22. The width of the outer peripheral part of the impeller 30 in the radial direction is set to be 1.3 to 2.2 mm. The interval Ds between the impeller 30 and the pump covers, 20, 22 in the axial direction is set to be 5 to 45 μm. The interval Dr between the impeller 30 and the pump cover 22 in the radial direction is set to be 50 to 300 μm. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fuel pump.

  2. Description of the Related Art Conventionally, a fuel pump that forms a plurality of blade grooves in the rotation direction of a disk-shaped impeller and pressurizes fuel sucked into a pressure increasing passage when the impeller rotates (see, for example, Patent Document 1). In such a fuel pump, for example, a higher discharge pressure is required due to a demand for improving atomization of fuel spray injected from a fuel injection valve. Although it is possible to increase the discharge pressure of the fuel pump by increasing the supply current to the motor part of the fuel pump, there is a problem that the power consumption of the fuel pump increases.

  Therefore, it is conceivable to increase the discharge pressure of the fuel pump without increasing the power consumption of the motor unit as much as possible by improving the pump efficiency of the pump unit. For example, in Patent Document 1, an attempt is made to increase the pump efficiency of the pump unit by gradually decreasing the passage area from the fuel inlet toward the boosting passage, thereby improving the efficiency of the fuel pump. Here, since the efficiency of the fuel pump is expressed by (motor efficiency) × (pump efficiency), if the pump efficiency is improved, the efficiency of the fuel pump is improved. The motor efficiency and the pump efficiency are: the drive current supplied to the motor part of the fuel pump is I, the applied voltage is V, the torque of the motor part is T, the rotational speed of the motor part is N, and the discharge pressure of the fuel discharged by the fuel pump Is P and the fuel discharge amount is Q, (motor efficiency) = (T × N) / (I × V), (pump efficiency) = (P × Q) / (T × N). Therefore, (fuel pump efficiency) = (motor efficiency) × (pump efficiency) = (P × Q) / (I × V). If the pump efficiency is improved, the fuel discharge pressure can be increased or the fuel discharge amount can be increased without increasing the power consumption of the fuel pump as much as possible.

  However, in the fuel pump as described above, since a sliding clearance is provided between the impeller and the pump cover that rotatably accommodates the impeller, the fuel flows between the impeller and the pump cover. There is a problem that the boosting efficiency of the fuel is lowered and the pump efficiency is lowered.

Japanese Unexamined Patent Publication No. 7-1899752

  The present invention has been made to solve the above-described problems, and an object thereof is to provide a fuel pump that improves pump efficiency.

In the first to third aspects of the invention, the annular outer peripheral portion of the impeller is provided to prevent the fuel from flowing between the impeller and the case member. Therefore, by increasing the width of the outer peripheral portion of the impeller in the rotational diameter direction and increasing the flow resistance of the flow path formed between the impeller and the case member, the fuel boosting efficiency can be increased.
However, when the width of the outer peripheral portion of the impeller is increased in the radial direction, the sliding resistance between the impeller and the case member also increases. That is, in order to increase the pump efficiency of the fuel pump, it is necessary to set the width of the outer peripheral portion of the impeller in the rotational radial direction within a predetermined range.

  Accordingly, in the inventions according to claims 1 to 3, the discharge pressure is set to 300 to 500 kPa and the rotation speed by setting the width in the rotation radial direction of the outer peripheral portion of the impeller to 1.3 mm to 2.2 mm as described above. The pump efficiency of the fuel pump used at 6000 to 10000 r / min and the discharge amount 150 to 250 L / h is increased.

  On the other hand, by reducing the distance between the impeller and the case member in the rotation axis direction of the impeller, or by reducing the distance between the impeller and the case member in the radial direction of the impeller, that is, the sliding clearance between the impeller and the case member is reduced. By reducing the size, the flow channel area of the flow channel formed between the impeller and the case member can be reduced, and the flow channel resistance can be increased.

  However, the lower limit value of the distance between the impeller and the case member described above is designed in consideration of the dimensional tolerance of the impeller and the case member and the swelling of the impeller. Therefore, if the interval between the impeller and the case member is to be made smaller than the lower limit designed as described above, the dimensional tolerance of the impeller and the case member is strictly controlled, and the impeller and the case member are highly resistant to swelling. Due to the necessity of being formed of a material or the like, the manufacturing cost of the fuel pump increases.

  In the invention described in claim 2, the distance between the impeller and the case member in the rotation axis direction of the impeller is 5 μm to 45 μm. Therefore, the pump efficiency can be increased without increasing the manufacturing cost of the fuel pump according to the first aspect of the present invention.

  In the invention according to claim 3, the interval in the rotational radial direction of the impeller between the impeller and the case member is 50 μm to 300 μm. Therefore, the pump efficiency of the fuel pump can be increased without increasing the manufacturing cost of the fuel pump according to the first aspect of the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
A fuel pump according to an embodiment of the present invention is shown in FIG. The fuel pump 10 is an in-tank type turbine pump mounted in a fuel tank of a vehicle, for example, and supplies the fuel in the fuel tank to a fuel injection valve (not shown). The fuel pump 10 has a discharge pressure of 300 to 500 kPa, a discharge amount of 150 to 250 L / h, and a rotation speed of 6000 to 10,000 rpm.

(Configuration of fuel pump)
As shown in FIG. 2, the fuel pump 10 includes a pump unit 12 and a motor unit 13 that rotationally drives the pump unit 12. The housing 14 also serves as a housing for the pump unit 12 and the motor unit 13, and crimps the end cover 16 and the pump cover 20.

  The pump unit 12 is a turbine pump having pump covers 20 and 22 and an impeller 30. The pump cover 22 is press-fitted into the housing 14 and abuts against the step portion 15 of the housing 14 in the axial direction. The pump covers 20 and 22 are case members that accommodate the impeller 30 in a rotatable manner. As shown in FIG. 3, C-shaped pressure increasing passages 202 and 203 are formed between the pump covers 20 and 22 and the impeller 30, respectively. That is, the pressure increasing passages 202 and 203 are formed on both sides in the thickness direction, which is the axial direction of the impeller 30, respectively. Note that an arrow 302 in FIG. 3 indicates the rotation direction of the impeller 30.

  As shown in FIG. 4, the impeller 30 formed in a disk shape is provided with a plurality of blade grooves 36 in the rotation direction, and an annular outer peripheral portion 32 is formed outside the blade grooves 36 in the rotation radial direction. Yes. When the impeller 30 rotates together with the shaft 51 by the rotation of the armature 50 shown in FIG. 2, the fuel that has flowed into the pressure increasing passages 202 and 203 from the outer radial direction of the vane groove 36 at the front in the rotational direction is transferred to the blade groove 36 at the rear in the rotational direction. It flows inward in the radial direction.

  By repeating such outflow and inflow of the fuel many times between the blade grooves 36, the fuel becomes a swirl flow 300 and is pressurized in the pressure increasing passages 202 and 203 (see FIG. 3). The fuel sucked from the fuel inlet 200 (see FIG. 3B) provided in the pump cover 20 by the rotation of the impeller 30 is pressurized by the pressure increase passages 202 and 203 on both sides in the thickness direction of the impeller 30 by the rotation of the impeller 30. From the discharge port 206 (see FIG. 3 (A)) provided in the pump cover 22, it is pumped to the motor unit 13 side.

  The fuel pressurized by the pressure increase passage 202 on the fuel inlet 200 side of the impeller 30 passes through the blade groove 36 in the vicinity of the discharge port 206 and moves to the pressure increase passage 203 on the discharge port 206 side. 13 is pumped. The fuel pumped into the motor unit 13 passes through the fuel passage 208 between the permanent magnet 42 and the armature 50 and is supplied to the engine side from the discharge port 210 provided in the end cover 16. An air vent hole 204 provided in the pump cover 20 shown in FIG. 3 (B) is for exhausting the air contained in the fuel in the pressure increasing passages 202 and 203 to the outside of the fuel pump 10.

As shown in FIG. 2, a plurality of permanent magnets 42 are attached to the inner peripheral wall of the housing 14 on the circumference. Adjacent permanent magnets 42 form magnetic poles having different poles in the rotation direction.
A commutator 70 is assembled at the end of the armature 50 opposite to the impeller 30. The shaft 51 of the armature 50 is supported by the bearing member 24, and the bearing members 24 on both sides of the shaft 51 are supported by the bearing holder 40 and the pump cover 22, respectively.
As the commutator 70 rotates and sequentially contacts a brush (not shown), the current supplied to the coil of the armature 50 is rectified. The permanent magnet 42, the armature 50, the commutator 70, and the brush (not shown) constitute a DC motor.

(Flow path configuration near the impeller)
As shown in FIG. 4, the circumferential width of the blade groove 36 is not uniform. Therefore, the blade grooves 36 are arranged at unequal pitches in the rotation direction. The blade grooves 36 adjacent to each other in the rotational direction of the impeller 30 are partitioned by a V-shaped partition wall 34 that is inclined forward from the substantially center in the thickness direction of the impeller 30 toward both end surfaces 31 in the thickness direction of the impeller 30 in the rotational direction. (See FIG. 5B). In addition, as shown in FIG. 1, a part of the inner side of the blade groove 36 in the rotational radial direction is partitioned by a partition wall 35 that protrudes from the inner side of the blade groove 36 toward the outer side of the rotational radial direction. The outer side in the direction of the rotation diameter penetrates in the direction of the rotation axis.
As a result, the fuel that has flowed into the blade groove 36 from the pressure-increasing passages 202 and 203 on both sides in the rotation axis direction becomes a swirl flow 300 that rotates in the opposite direction on both sides in the rotation axis direction by the partition wall 35, thereby sucking in from the fuel inlet 200. The increased fuel is pressurized in the pressure increasing passages 200 and 202.

  However, since a sliding clearance is provided between the impeller 30 and the pump covers 20 and 22, the fuel flows between the impeller 30 and the pump covers 20 and 22, thereby boosting the fuel by the impeller 30. Efficiency decreases. Specifically, in the fuel pump 10 that is set to a discharge pressure of 300 to 500 kPa, a discharge amount of 150 to 250 L / h, and a rotation speed of 6000 to 10,000 rpm, the rotation of the outer peripheral portion 32 of the impeller 30 as shown in FIG. When the radial width (hereinafter referred to as the width of the outer peripheral portion 32) W is smaller than 1.3 mm, the flow resistance of the flow path formed between the impeller 30 and the pump covers 20 and 22 is reduced, and the impeller The flow rate of the fuel flowing between 30 and the pump covers 20 and 22 increases. As described above, when the flow rate of the fuel flowing between the impeller 30 and the pump covers 20 and 22 increases, the boosting efficiency of the fuel decreases. On the other hand, when the width W of the outer peripheral portion 32 is wider than 2.2 mm, the sliding resistance between the impeller 30 and the pump covers 20 and 22 increases.

  Therefore, by setting the width W of the outer peripheral portion 32 of the impeller 30 to 1.3 mm to 2.2 mm, the pressure increase efficiency of the fuel is enhanced while suppressing the sliding resistance between the impeller 30 and the pump covers 20 and 22. Thus, the pump efficiency of the fuel pump 10 is increased.

  Further, the distance Ds (see FIG. 1) between the impeller 30 and the pump covers 20 and 22 in the rotational axis direction is set to 5 μm to 45 μm, and the distance Dr (see FIG. 1) between the impeller 30 and the pump cover 22 in the rotational radial direction. Is set to 50 μm to 300 μm.

  Here, the distance in the rotation axis direction between the impeller 30 and the pump covers 20 and 22 (hereinafter referred to as side clearance) Ds is made smaller than 5 μm, or the distance in the rotation diameter direction between the impeller 30 and the pump cover 22 (hereinafter referred to as “side clearance”). Radial clearance.) When Dr is reduced, it is necessary to strictly manage the dimensional tolerances of the impeller 30 and the pump covers 20 and 22, and to form the impeller 30 and the pump covers 20 and 22 from a material having high swelling resistance. As a result, the manufacturing cost of the fuel pump 10 increases. On the other hand, when the side clearance Ds is made larger than 45 μm or the radial clearance Dr is made larger than 300 μm, the flow area of the flow path formed between the impeller 30 and the pump covers 20 and 22 is increased, and the flow resistance is increased. As a result of the reduction, the boosting efficiency of the fuel decreases, and the fuel discharge amount decreases (see FIGS. 7 and 8).

  Therefore, the side clearance Ds that is the distance between the impeller 30 and the pump covers 20 and 22 in the rotational axis direction is set to 5 μm to 45 μm, and the radial clearance Dr that is the distance between the impeller 30 and the pump cover 22 in the rotational radial direction is 50 μm. By setting to ˜300 μm, the fuel boosting efficiency is increased without increasing the manufacturing cost of the fuel pump 10, and the pump efficiency of the fuel pump 10 is increased.

(Other embodiments)
In the above embodiment, the configuration of the fuel pump 10 has been specifically described. However, the fuel pump according to the present invention is a fuel pump having a discharge pressure of 300 to 500 kPa, a discharge amount of 150 to 250 L / h, and a rotation speed of 6000 to 10000 rpm. Any fuel pump may be used as long as the width in the radial direction, the side clearance Ds, and the radial clearance Dr are within the above-mentioned dimensions, and the configuration is not limited to the configuration of the fuel pump 10 illustrated.

As long as the fuel pump that satisfies the above specifications can be designed by setting the width of the outer peripheral portion 32 of the impeller 30 in the rotational radial direction to 1.3 mm to 2.2 mm, either the side clearance Ds or the radial clearance Dr. May be outside the above range, or both may be outside the above range.
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.

The enlarged view of the impeller vicinity of the fuel pump by one Embodiment of this invention. 1 is a cross-sectional view showing a fuel pump according to an embodiment of the present invention. (A) is explanatory drawing which shows the pump cover on the discharge side, (B) is explanatory drawing which shows the pump cover on the suction side. (A) is the perspective view which looked at the impeller from the suction side, (B) is an enlarged view of the blade groove part of (A). (A) is the schematic diagram which looked at the blade groove | channel of the impeller from the suction side, (B) is the BB sectional drawing of (A). The characteristic view which shows the relationship between the width | variety of the outer peripheral part of an impeller, and pump efficiency. The characteristic view which shows the relationship between a side clearance and discharge amount. The characteristic view which shows the relationship between radial clearance and discharge amount.

Explanation of symbols

10: Fuel pump, 13: Motor part, 20: Pump cover (case member), 22: Pump cover (case member), 30: Impeller, 32: Outer peripheral part, 36: Blade groove

Claims (3)

A motor section;
An impeller that is rotationally driven by the motor unit and has a plurality of blade grooves provided in the rotation direction and an outer peripheral portion formed in an annular shape on the outer side in the rotation radial direction of the blade grooves, and pressurizes the fuel;
A case member that rotatably accommodates the impeller,
The fuel pump according to claim 1, wherein a width of the outer peripheral portion in the radial direction is 1.3 mm to 2.2 mm.   2. The fuel pump according to claim 1, wherein an interval between the impeller and the case member in a rotation axis direction is 5 μm to 45 μm. 3. The fuel pump according to claim 1, wherein a distance between the impeller and the case member in a rotation radial direction is 50 μm to 300 μm.

Images