JP2003293880A - Fuel pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel pump, in which high efficiency is implemented, rising of fuel discharge pressure is expedited upon starting, and fluctuation in fuel discharge amount by vapor is small. <P>SOLUTION: A vapor discharge port 62 makes a pump flow passage mutually communicate to an outer space of the fuel pump, that is, an inner space of a fuel tank. An angle θ of a center of arrangement of the vapor discharge port is set to be positive pressure of approximately 15% or more and 30% or less of fuel discharge pressure. The angle θ of the center of arrangement of the vapor discharge port is determined according to pump flow passage structure. By setting the angle θ of the center of arrangement of the vapor discharge port, retention of vapor in the pump flow passage is prevented, lowering of efficiency of the fuel pump caused by forming of the vapor discharge port 62 is suppressed, and the rising of the fuel discharge pressure upon starting is expedited. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel pump that rotates an impeller to suck fuel from a fuel tank.

[0002]

2. Description of the Related Art Conventionally, an ECU is used depending on the engine operating state.
A fuel supply system that adjusts the discharge amount of a fuel pump is known. Vapor is generated in the fuel supply system due to heat received from the engine. When the amount of fuel supplied to the engine is large, the vapor in the pump passage of the fuel pump can be discharged together with the fuel from the fuel discharge port of the pump.
During low-power operation such as idling, the amount of fuel supplied to the engine is small. Therefore, when the temperature of the fuel becomes high, the vapor easily stays in the pump passage. When the vapor stays in the pump passage, the fuel discharge amount decreases, and when the vapor stays accumulated, vapor lock occurs. Tokkyo 3-6
Japanese Patent No. 1038 discloses a fuel pump provided with a vapor discharge port for discharging vapor from a pump passage.

FIG. 5 is a plan view showing a pump channel disclosed in Japanese Patent Publication No. 3-61038. The vertical cross-sectional shape of the pump channel is C along the outer peripheral edge of the impeller (not shown).
The lower groove 10 having a V shape and formed in the lower partition 104.
6 and an upper groove formed on an upper partition (not shown) that covers the lower partition 104 and the outer peripheral edge of the impeller. A fuel intake port 100 formed in the lower partition wall 104 communicates with a fuel tank, and an exhaust port (not shown) formed in the upper partition wall communicates with a fuel pipe to the engine. When the impeller rotates, fuel is sucked from the fuel tank into the pump passage through the fuel inlet 100, the fuel is boosted as it flows through the pump passage toward the outlet, and the fuel that has reached the predetermined exhaust pressure is pump passage. Is discharged through the discharge port.
The vapor outlet 1 is located at a position sufficiently distant from the fuel inlet 100.
By forming No. 02 and setting the fuel pressure at the vapor discharge port 102 to be high, it is possible to reliably discharge the vapor from the pump flow passage when vapor lock is likely to occur during high temperature and low output operation. It intersects with the central axis of the impeller, and passes through the vapor discharge port 102 and the end of the fuel fuel suction port 100.
The angle θ formed by the line segments of the book is set to about 100 ° in order to reliably discharge the vapor.

[0004]

However, the fuel is discharged from the vapor discharge port 102 together with the vapor. In the pump flow path, the fuel pressure increases as the distance from the fuel suction port 100 increases.
The fuel leakage from the vapor discharge port 102 increases as the distance from the vapor discharge port 102 increases. Therefore, as the vapor discharge port 102 is separated from the fuel suction port 100, the efficiency of the fuel pump decreases.

On the other hand, the vapor discharge port 102 is connected to the fuel suction port 1
If the fuel discharge pressure is close to 00, the fuel pressure at the vapor discharge port 102 becomes low and the vapor stays in the pump flow path, which causes a problem of vapor lock during low-power operation, and the rise of the fuel discharge pressure at the start is slow. Again, vapor outlet 10
There is also a risk that fuel will be inhaled from 2.

The present invention was created in order to solve such a problem, and an object thereof is to provide a fuel pump having a high efficiency and a small fluctuation in fuel discharge amount due to vapor. It is another object of the present invention to provide a fuel pump in which the fuel discharge pressure rises quickly at the time of start-up and the fluctuation of the fuel discharge amount due to vapor is small. Another object of the present invention is to provide a fuel pump having high efficiency, quick rise of the fuel discharge pressure at the time of starting, and small fluctuation of the fuel discharge amount due to vapor.

[0007]

[Means for Solving the Problems] In order to solve the above problems, the correlation between the position of the vapor discharge port, efficiency, startability, and change in the amount of discharge at high temperature was repeatedly verified and verified. The correlation shown in 2 was discovered. The horizontal axis of each graph in FIG. 2 indicates the pressure of the fuel detected at the vapor discharge port when the vapor discharge port is provided at each position of the pump passage, and the pressure of the fuel discharged from the fuel discharge port (fuel discharge The pressure is expressed as a percentage. The pressure in the pump channel was detected by operating the fuel pump with a large number of holes made in the partition wall of the pump channel and inserting the pressure gauge needles into these holes. As shown in FIG. 2 (A), the efficiency drops as the fuel pressure detected at the position where the vapor discharge port is provided increases, but when the fuel pressure detected at the position where the vapor discharge port is provided exceeds 30%. The slope of change becomes steep. As shown in FIG. 2B, the time (rise time) required until the exhaust fuel pressure at startup is increased to a predetermined pressure is when the vapor exhaust port is provided at a position where the fuel pressure is close to 30%. The shortest. As shown in FIG. 2C, the change in the discharge amount (flow amount change amount) detected when the temperature is raised under a constant driving condition is determined by the fuel pressure detected at the position where the vapor discharge port is provided. The slope of the change becomes steep around 30%.

In the fuel pump according to the first or fifth aspect, since the fuel pump has the vapor discharge port for discharging the vapor from the pump flow passage in the section where the fuel pressure is a positive pressure, the vapor is not retained in the pump flow passage. Further, by discharging the vapor from the pump flow path through the vapor discharge port in the section where the fuel pressure is approximately 30% or less of the fuel discharge pressure, it is possible to suppress a decrease in efficiency due to the formation of the vapor discharge port. Therefore, the fuel pump according to the first aspect has a high efficiency and a small variation in the amount of fuel discharged by the vapor.

In the fuel pump according to the second or fifth aspect, since the fuel pump has the vapor discharge port for discharging the vapor from the pump flow passage in the section where the fuel pressure is a positive pressure, the vapor is not retained in the pump flow passage. Further, by discharging the vapor from the pump flow path through the vapor discharge port in the section where the fuel pressure is approximately 15% or more and 45% or less of the fuel discharge pressure, it is possible to accelerate the rise of the discharged fuel pressure at the time of starting. Therefore, in the fuel pump according to the second aspect of the present invention, the discharge fuel pressure rises quickly at the time of starting, and the fluctuation of the fuel discharge amount by the vapor is small.

In the fuel pump according to the third or fifth aspect, since the fuel pump has the vapor discharge port for discharging the vapor from the pump flow passage in the section where the fuel pressure is a positive pressure, the vapor is not retained in the pump flow passage. Further, in a section where the fuel pressure is approximately 15% or more and 30% or less of the fuel discharge pressure, the vapor is discharged from the pump flow path through the vapor discharge port, thereby suppressing a decrease in efficiency due to forming the vapor discharge port. It is also possible to accelerate the rise of the fuel discharge pressure at the start. Therefore, the fuel pump according to the third aspect has high efficiency, the fuel discharge pressure rises quickly at the time of starting, and the fluctuation of the fuel discharge amount by the vapor is small.

In the fuel pump according to the fourth or fifth aspect of the present invention, the centrifugal side contour of the cross section of the pump flow path is C-shaped in the section from the fuel suction port to the vapor discharge port. It is possible to efficiently pressurize the fuel in the pump passage in the section up to. Therefore,
Since the section length from the fuel inlet to the vapor outlet can be shortened and the section length from the vapor outlet to the fuel outlet can be extended, the efficiency can be further enhanced.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below based on Examples. FIG. 3 is a schematic diagram showing an overall configuration of a fuel supply system including a fuel pump 10 according to an embodiment of the present invention. First, the fuel supply system will be described. The fuel pump 10 is an in-tank type that is housed in a fuel tank 84 of an automobile.
The fuel 86 stored in No. 4 is filtered by the filter 88 and sucked. The fuel discharged from the fuel pump 10 is the fuel pipe 7
It is supplied to the accumulator pipe 78 through the high pressure fuel filter 72 attached to Nos. 0 and 76. The fuel is stored at a predetermined pressure by the storage tube 78, and is injected into the cylinder from an injector 80 provided in each cylinder of the engine. This fuel supply system is a returnless type in which fuel is returned in-tank.

The ECU 82 determines the fuel discharge pressure of the fuel pump 10 on the basis of signals input from various sensors for detecting the engine operating state, and sends a control signal to the fuel pump controller 74. The fuel pump controller 74 duty-controls the current applied to the fuel pump 10 from a power source (not shown) to a magnitude according to the control signal of the ECU 82. The fuel pump 10 discharges fuel into the fuel pipe 70 at a pressure according to the electric current controlled by the fuel pump controller 74. By adjusting the fuel discharge pressure of the fuel pump 10, the fuel pressure in the storage tube 78 is adjusted.

Next, the overall structure of the fuel pump 10 will be described. FIG. 4 shows a fuel pump 1 according to an embodiment of the present invention.
It is sectional drawing which shows 0. A motor that is a drive source of the fuel pump 10 is a DC motor with a brush, and has a configuration in which a permanent magnet is annularly arranged in a cylindrical housing 20, and an armature 22 is arranged on the inner peripheral side of this permanent magnet. .

An upper partition wall 26 of the pump channel 30 is press-fitted and fixed to the lower end of the cylindrical housing 20. The lower partition wall 32 of the pump flow path 30 so as to cover the upper partition wall 26.
Is fixed to the lower end of the housing 20 by caulking or the like. The upper partition wall 26 and the lower partition wall 32 are, for example, aluminum die castings. The connector body 16 is fixed to the upper end of the housing 20 by caulking or the like. A space left around the armature 22 in the housing 20 constitutes a fuel chamber 46.

A lower bearing 24 is provided at the center of the upper partition wall 26. The thrust bearing 3 is provided at the center of the lower partition wall 32.
6 is provided. The lower end of the shaft portion 44 of the armature 22 is rotatably supported by the lower bearing 24 in the radial direction,
It is rotatably supported in the axial direction by a thrust bearing 36. The upper end of the shaft portion 44 of the armature 22 is rotatably supported by the upper bearing 50 in the radial direction.

The impeller 37 includes an upper partition 26 and a lower partition 3.
It is rotatably accommodated between the two. The lower end of the shaft portion 44 of the armature 22 is formed in a D-shaped cross section, and the impeller 37 is fixed to that portion of the shaft portion 44 by press fitting or the like. The impeller 37 has a large number of blades 40 formed all around the outer peripheral edge and blade grooves 42 formed between the blades 40 adjacent to each other.

The fuel inlet 34 is formed in the lower partition wall 32. Upper partition wall 2 remaining around the periphery of the impeller 37
The remaining space between 6 and the lower partition wall 32 is the pump flow path 30. The pump flow path 30 is defined by an upper groove 28 formed in the upper partition wall 26, a lower groove 38 formed in the lower partition wall 32, and the outer peripheral edge of the impeller 37, and its vertical cross-sectional shape is defined as a C-shape.

The rotation of the impeller 37 causes the fuel in the fuel tank 84 to flow from the fuel inlet 34 to the pump passage 30.
Inhaled into. The fuel sucked into the pump passage 30 is pressurized by the rotation of the impeller 37, and is discharged into the fuel chamber 46 from a discharge port (not shown) formed in the upper partition wall 26.

The fuel outlet 14 is formed in the connector body 16. The fuel discharged into the fuel chamber 46 is discharged from the fuel discharge port 14 into the fuel pipe 70. Fuel outlet 14
A check valve member 12 is provided in the valve, and the check valve member 12 prevents the reverse flow of fuel from the fuel pipe 70 to the fuel pump 10.

Next, the structure of the pump passage 30 will be described in detail. FIG. 1 is a sectional view taken along line I-I of FIG. The lower groove 38 formed in the lower partition wall 32 includes an introducing portion 64, a pressure increasing portion 60, and a discharging portion 66.

The profile of the vertical cross section of the introduction portion 64 is formed in an arc shape with a constant radius of curvature on the inner peripheral side and on the outer peripheral side.
It is formed in an arc shape whose diameter decreases as it approaches. The fuel inlet 34 is opened in the introduction portion 64. The introduction portion 64 is formed so that the flow passage cross-sectional area is reduced as it approaches the booster portion 60. The portion near the fuel intake port 34 is relatively wide and deep, and the portion near the introduction portion 64 is relatively wide. The width is narrow and shallow. In the introduction section 64, the boosting section 6
The fuel pressure increases from negative pressure to positive pressure as it approaches zero.

As shown in FIGS. 1C and 1D, the cross-sectional contour of the introduction portion 64 is as shown in FIGS. 1C and 1D from the end of the fuel inlet 34 near the vapor outlet 62 to the vapor outlet 62. It has an arc shape. Further, the contour of the cross section of the upper groove 28 is formed in an arc shape in the entire section (see FIG. 4). Therefore,
In the section corresponding to the introduction portion 64, the centrifugal profile of the cross section of the pump flow channel 30 is substantially C-shaped. Therefore, in the section from the fuel inlet 34 to the vapor outlet 62,
The vane groove 42, the upper groove 28, and the lower groove 38 of the impeller 37 form a fuel flow with little turbulence. Therefore, it is possible to efficiently pressurize the fuel in the pump passage 30 in the section from the fuel suction port 34 to the vapor discharge port 62. Therefore, the section length of the introduction section 64 can be shortened and the section length of the booster section 60 can be extended, whereby the efficiency of the fuel pump 10 can be improved.

The cross-sectional shape of the booster section 60 is arcuate over the entire section, and the booster section 60 has a constant passage cross-sectional area over the entire section. The step-up portion 60 has a vertical cross section formed in a C shape, and the contour of the vertical cross section is formed in an arc shape having a constant radius of curvature on the inner peripheral side and the outer peripheral side. Booster 6
At 0, the fuel pressure increases linearly from the introduction portion 64 to the discharge portion 66.

The discharge portion 66 is formed at a position facing the discharge port formed in the upper partition wall 26. The discharge portion 66 becomes shallower as it goes away from the booster portion 60, so that the turbulent flow of fuel toward the discharge port is reduced.

The vapor discharge port 62 has an inlet 64 and a pressure booster 6.
It opens near the boundary of 0. The vapor discharge port 62 communicates the pump flow path 30 with the external space of the fuel pump 10, that is, the internal space of the fuel tank 84. It intersects with the central axis of the impeller 37 and the vapor discharge port 62.
The angle between two line segments passing through the fuel suction port 34 and the end of the fuel suction port 34 (hereinafter referred to as the center angle of the vapor discharge port arrangement) θ is the pump flow in the cross section passing through the vapor discharge port 62. Road 3
The fuel pressure within 0 (vapor discharge pressure) is the fuel discharge port 14
The fuel pressure (fuel discharge pressure) detected in (1) is set to be approximately 15% or more and 30% or less and a positive pressure with respect to the fuel pressure in the fuel tank 84. The arrangement central angle θ of the vapor discharge port is determined according to the configuration of the pump passage 30. In the pump channel 30 having the configuration shown in FIGS. 1 and 4,
When the arrangement central angle θ of the vapor discharge port was set to approximately 50 ° or more and 80 ° or less, the vapor discharge pressure became a positive pressure of approximately 15% or more and 30% or less of the fuel discharge pressure. By setting the arrangement center angle θ of the vapor discharge port as described above, it is possible to prevent the vapor from accumulating in the pump flow path 30, and the efficiency of the fuel pump 10 due to the formation of the vapor discharge port 62. Can be suppressed, and also
It is possible to accelerate the rise of the fuel discharge pressure at the time of starting.

For the purpose of only suppressing the decrease in the fuel discharge amount caused by the accumulation of vapor in the pump passage 30,
The arrangement center angle θ of the vapor discharge port may be set so that the vapor discharge pressure becomes a positive pressure of approximately 30% or less of the fuel discharge pressure. Further, for the purpose of only speeding up the rise of the exhaust fuel pressure at the time of start-up, if the vapor discharge port arrangement center angle θ is set so that the vapor discharge pressure is approximately 15% or more and 45% or less of the fuel discharge pressure. Good.

Next, the flow of vapor and fuel in the pump passage 30 will be described. The vapor is the fuel tank 84.
On the other hand, a large amount is generated in the vicinity of the fuel suction port 34 where a negative pressure is generated. When the fuel is sucked into the pump passage 30 from the fuel suction port 34, the vapor is sucked into the pump passage 30 together with the fuel. The fuel is gradually pressurized in a section of the pump passage 30 corresponding to the introduction portion 64, and becomes a positive pressure with respect to the fuel pressure in the fuel pump 10 before flowing to the opening of the vapor discharge port 62. When the vapor flows with the fuel to the opening of the vapor discharge port 62, the vapor has a positive pressure with respect to the fuel pressure in the fuel tank 84 at the opening of the vapor discharge port 62. Is discharged to the outside. Since the pump passage 30 has a positive pressure with respect to the fuel tank 84 at the opening of the vapor discharge port 62, the fuel not filtered by the filter 88 flows from the fuel tank 84 to the pump passage 30 through the vapor discharge port 62. Not inhaled.

The embodiments of the present invention have been described above based on the embodiments. Next, set the vapor discharge outlet at a central angle of 55.
The results of verifying the effects of this embodiment by setting the angle of 120 ° and 120 ° will be described.

When the arrangement central angle θ of the vapor discharge port was set to 55 ° within the range of this embodiment, the flow rate of the fuel discharged from the vapor discharge port 62 was 11 liters / hour. The central angle θ of arrangement of the vapor discharge port is 55 ° within the range of this embodiment.
It was confirmed that fuel was not drawn in from the vapor discharge port 62 when set to.

When the arrangement central angle θ of the vapor discharge port was set to 120 °, which is outside the range of this embodiment, the flow rate of the fuel discharged from the vapor discharge port 62 was 25 liters / hour.
The arrangement central angle θ of the vapor discharge port is 12 within the range of this embodiment.
When set to 0 °, the fuel is not sucked from the vapor discharge port 62, but the fuel pressure in the pump passage 30 is high, so the flow rate of the fuel discharged from the vapor discharge port 62 increases, and the efficiency is increased. Becomes worse.

In the above-mentioned embodiment, the vapor discharge pressure is approximately 15% or more and 30% or less of the fuel discharge pressure, and the center of the vapor discharge port is arranged so as to be a positive pressure with respect to the fuel pressure in the fuel tank 84. Since the angle θ is set, it is possible to prevent the vapor from staying in the pump flow path and to prevent the efficiency from being reduced by forming the vapor discharge port. Can accelerate the rise of. Therefore, according to the above-described embodiment, the efficiency is high, the rise of the fuel discharge pressure at the time of starting is fast,
It is possible to realize a fuel pump in which fluctuations in fuel discharge amount due to vapor are small. Further, the fuel consumption of the vehicle can be suppressed by increasing the efficiency of the fuel pump and reducing the current applied to the coil.

Although the fuel pump 10 controlled by the fuel pump controller 74 has been described in the above embodiment, the present invention can also be applied to a fuel pump included in a fuel supply system that does not include a fuel pump controller.

[Brief description of drawings]

FIG. 1A is a sectional view taken along line I-I of FIG. 3, and FIG.
6A is a partial cross-sectional view showing the cross-sectional shape of the lower groove at the position indicated by arrow B in FIG. 7A, and FIG. 6C is a partial cross-sectional view showing the cross-sectional shape of the lower groove at the position indicated by arrow C in FIG. , (D) are partial cross-sectional views showing the cross-sectional shape of the lower groove at the position indicated by arrow D in (A).

FIG. 2A is a graph for explaining a correlation between a position of a vapor discharge port and efficiency, and FIG. 2B is a graph for explaining a correlation between a position of a vapor discharge port and startability. And (C) is a graph for explaining the correlation between the position of the vapor discharge port and the change in discharge amount at high temperature.

FIG. 3 is a schematic diagram showing an overall configuration of a fuel supply system including a fuel pump according to an embodiment of the present invention.

FIG. 4 is a sectional view showing a fuel pump according to an embodiment of the present invention.

FIG. 5 is a plan view showing an example of a conventional pump flow path provided with a vapor discharge port.

[Explanation of symbols]

10 Fuel pump 14 Fuel outlet 26 Upper partition 28 Upper groove 30 pump channels 32 Lower partition 34 Fuel inlet 38 Lower groove 37 Impeller 60 Booster 62 Vapor outlet 64 Introduction 66 Ejector θ Arrangement center angle of vapor discharge port

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F04D 29/44 F04D 29/44 BE

Claims (5)

[Claims] 1. A fuel pump for boosting the fuel sucked from a fuel suction port by an impeller in a pump passage and discharging the fuel from a fuel discharge port, wherein the fuel pressure is a positive pressure of about 30% or less of the fuel discharge pressure. 2. A fuel pump having a vapor discharge port for discharging vapor from the pump flow path. 2. A fuel pump for boosting the fuel sucked from a fuel suction port by an impeller in a pump passage and discharging the fuel from a fuel discharge port, wherein the fuel pressure is a positive pressure of approximately 15% to 45% of the fuel discharge pressure. The fuel pump is characterized in that it has a vapor discharge port for discharging vapor from the pump flow path in the following section. 3. A fuel pump for boosting the fuel sucked from a fuel suction port by an impeller in a pump passage and discharging it from a fuel discharge port, wherein the fuel pressure is a positive pressure of approximately 15% to 30% of the fuel discharge pressure. The fuel pump is characterized in that it has a vapor discharge port for discharging vapor from the pump flow path in the following section. 4. The centrifugal-side contour of the transverse cross section of the pump flow path in the section from the fuel suction port to the vapor discharge port is substantially C-shaped, according to claim 1, 2 or 3. Fuel pump. 5. The fuel pump according to claim 1, wherein the fuel pump is provided in a returnless fuel supply system.