JP2002202018A - Fuel pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce sliding resistance (friction loss) of an outer gear to a pump easing of a trochoidal gear type fuel pump and reduce the pulsation of delivery pressure. SOLUTION: Two inner gears 25, 26 are disposed with a partition wall 28 sandwiched between them with eccentricity on the inner peripheral side of the outer gear 24, and the eccentric directions of both inner gears 25, 26 are shifted from each other to the opposite sides by 180 deg.. Thus, the load in the direction of the outside diameter due to fuel pressure rise is applied from two inner gears 25, 26 to one outer gear 24 in the opposite directions by 180 deg. not to be offset load, so that the sliding resistance of the outer gear 24 to the cylindrical easing 21 is reduced. The number of teeth of the outer gear 24 is set to an odd number, and the number of teeth of the inner gears 25, 26 is set to an even number. Thus, the rotational phases of two inner gears 25, 26 are shifted by half pitch, the phases of pulsation wave of delivery output of two inner gears 25, 26 are shifted by half period of the pulsation wave so as to reduce the pulsation of delivery pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a trochoid gear type fuel pump in which an inner gear is eccentrically arranged on the inner peripheral side of an outer gear.

[0002]

2. Description of the Related Art In recent years, the use of a trochoid gear type fuel pump has been studied in order to improve the fuel discharge performance of a fuel pump mounted on a vehicle. In this trochoid gear type fuel pump, as shown in FIG. 7, an inner gear 3 with external teeth is eccentrically arranged on an inner peripheral side of an outer gear 2 with internal teeth rotatably housed in a cylindrical pump casing 1. At the same time, the two gears 2 and 3
A pump chamber 4 is formed between the teeth of the drive motor (not shown).
By rotating the inner gear 3 to rotate the outer gear 2, the volume of the pump chamber 4 is continuously increased / decreased while moving the pump chamber 4 between the teeth of the two gears 2 and 3 in the rotation direction. To suck and discharge fuel.

[0003]

In such a trochoid gear type fuel pump, since the volume of the pump chamber 4 is repeatedly changed, a discharge pressure pulsation having a frequency corresponding to the number of teeth of the inner gear 3 is generated. There is a disadvantage that the fuel tank, the fuel pipe, the floor panel of the vehicle, and the like are vibrated due to the pulsation, thereby increasing noise and vibration. For this reason, when using a trochoid gear type fuel pump, measures to reduce noise such as installing a discharge pressure pulsation reduction device outside the fuel pump or attaching a sound insulating material to the vehicle body are used to reduce noise and vibration. However, there is a disadvantage that the cost is increased.

In the trochoid gear type fuel pump, the volume of the pump chamber 4 decreases after the fuel is sucked into the pump chamber 4 in a region where the volume of the pump chamber 4 increases due to the rotation of the gears 2 and 3. The pressure in the pump chamber 4 is increased and discharged in the region where the pressure rises. At this time, in the discharge region where the volume of the pump chamber 4 is reduced, the fuel in the pump chamber 4 is pressurized and the fuel pressure (fuel pressure) increases, so that the outer pressure is applied to the outer gear 2 due to the increase in the fuel pressure. . The load in the outer diameter direction due to such a rise in fuel pressure is reduced by the pump chamber 4.
Does not occur in the suction region (suction port side) where the fuel pressure in the inside decreases, so that the load in the outer radial direction on the outer gear 2 is
Discharge area where the fuel pressure of pump chamber 4 rises (discharge port side)
This acts as an eccentric load, and a part of the outer gear 2 on the discharge port side is strongly pressed against the inner peripheral surface of the pump casing 1. For this reason, the sliding resistance (friction loss) of the outer gear 2 with respect to the pump casing 1 increases, and accordingly, the load on the drive motor increases, so that the power consumption increases or the fuel discharge performance decreases (the pump rotation speed decreases). Lowering).

The present invention has been made in view of these circumstances, and a first object is to provide a fuel pump which can reduce noise and vibration caused by pulsation of discharge pressure at low cost. A second object is to provide a fuel pump that can reduce the sliding resistance (friction loss) of the outer gear with respect to the pump casing, thereby reducing the power consumption of the drive motor and improving the fuel discharge performance.

[0006]

In order to achieve the first object, a trochoid gear type fuel pump according to a first aspect of the present invention is provided with two pumps each including an outer gear and an inner gear. The pump is configured such that the phases of the pulsations of the discharge pressure of the pumps are merged while interfering with each other with a phase shift of about a half wavelength (half cycle). According to this configuration, when the pressure pulsation wave of the fuel discharged from one of the pumps has a peak, the other becomes a valley, and the discharge pressure pulsations of the two pumps interfere with each other and cancel each other. Is significantly reduced, and noise and vibration due to the discharge pressure pulsation are greatly reduced. This eliminates the need for conventional noise countermeasures (e.g., a discharge pressure pulsation reduction device and a sound insulating material), and realizes low noise and low vibration at low cost.

[0007] In this case, the following two configurations can be considered as a configuration in which the phases of the discharge pressure pulsations of the two pumps merge with a shift of approximately half a wavelength. For example, if the length of the fuel flow path from the discharge ports of the two pumps to the fuel junction is shifted by about a half wavelength (or an odd multiple of the half wavelength), two discharge pressure pulsations occur at the fuel junction. Are shifted by about a half wavelength, and the discharge pressure pulsations interfere with each other and cancel each other. However, in this configuration, it is necessary to lengthen the fuel flow path from the discharge ports of the two pumps to the fuel junction to a certain extent,
Accordingly, there is a disadvantage that the fuel pump becomes large.

Therefore, it is preferable to adopt a configuration in which the rotational phases of the two pumps are shifted from each other by approximately a half pitch.
With this configuration, the phases of the discharge pressure pulsations of the discharge ports of the two pumps are shifted by about a half wavelength, so that the length of the fuel flow path from the discharge ports of the two pumps to the fuel confluence is a half wavelength (or Even if there is no deviation (an odd multiple of a half wavelength), the phases of the two discharge pressure pulsations are shifted by almost a half wavelength at the fuel junction, and the discharge pressure pulsations interfere with each other and cancel each other out. For this reason, it is possible to adopt a configuration in which fuel is merged in the vicinity of the discharge ports of the two pumps, and there is an advantage that the fuel pump can be downsized accordingly.

According to a third aspect of the present invention, the outer gears of the two pumps are integrally formed, and the two inner gears are eccentrically arranged on the inner peripheral side of one outer gear with the partition wall interposed therebetween. The configuration may be such that the eccentric directions of the two inner gears with respect to the outer gear are shifted to opposite sides by 180 ° from each other. In this configuration, the two inner gears disposed on the inner peripheral side of the outer gear have respective eccentric directions that are one to one.
Because it is shifted to the opposite side by 80 °, the two inner gears
The fuel pressure rising sides (discharge ports) are shifted by 180 ° from each other. As a result, a load in the outer diameter direction due to a rise in fuel pressure from one inner gear to another outer gear is 1
Since it acts on the opposite side by 80 °, the load in the outer radial direction acting on the outer gear is balanced, and almost no eccentric load acts on the outer gear. For this reason, the outer gear is not strongly pressed against the inner peripheral surface of the pump casing by the fuel pressure, and the sliding resistance (friction loss) of the outer gear with respect to the pump casing becomes smaller than before, and accordingly,
The load on the drive motor is reduced, and power consumption is reduced. Moreover, since the fuel is sucked and discharged by the two inner gears in the outer gear, the fuel discharge performance can be effectively improved in combination with the above-described sliding resistance reduction effect. Thus, the configuration of claim 3 can achieve both the first and second objects.

Further, the outer gears of the two pumps are formed separately, and one outer gear is formed on the inner peripheral side of each outer gear.
Two pumps having two eccentric inner gears may be arranged so as to overlap each other, and the eccentric directions of the gears may be shifted by 180 ° between the two pumps.
Even with this configuration, the fuel pressure rise side between the two pumps is shifted to the opposite side by 180 °, so that the loads in the outer diameter direction act on the opposite sides by 180 ° from both pumps, and the entire fuel pump has the outer diameter direction. Can be balanced, and the vibration of the fuel pump can be reduced.

In general, in a trochoid gear type fuel pump, the number of teeth of the inner gear should be one less than the number of teeth of the outer gear.
In the configuration in which the outer gears of the two pumps are driven to rotate in the same phase by a motor in the configuration shifted to the opposite side by 0 °, if the number of teeth of the outer gear on the driving side is even (the number of teeth of the inner gear on the driven side is odd), the driven The rotation phases of the two inner gears on the side coincide. In this state, the phases of the pulsation waves of the discharge pressures of the two pumps match, and when the discharge pressure pulsation wave of one of the pumps has a peak (valley), the other also has a peak (valley). Pressure pulsations amplify each other, and noise and vibration due to discharge pressure pulsations increase.

As a countermeasure, when the outer gears of the two pumps are rotationally driven by the motor in the same phase as in claim 5, the number of teeth of the outer gear on the drive side is set to an odd number,
It is preferable that the number of teeth of the driven inner gear driven to rotate by the outer gear is an even number smaller by one than the number of teeth of the outer gear. With this configuration, the rotational phases of the two driven inner gears are shifted by half a pitch, and the discharge pressure pulsations of the two pumps interfere with each other and cancel each other, so that the discharge pressure pulsation is greatly reduced, and the discharge pressure pulsation is reduced. Noise and vibration due to pulsation are greatly reduced.

When the inner gears of the two pumps are rotationally driven by the motor in the same phase, the number of teeth of the driving inner gear is even (the number of teeth of the driven outer gear is odd).
Since the rotational phases of the two outer gears on the driven side coincide with each other, the number of teeth of the inner gear on the driving side is set to an odd number, and the number of teeth of the outer gear on the driven side is set to be one less than the number of teeth of the inner gear. It is good to use even number. By doing so, the rotational phases of the two outer gears on the driven side are shifted by half a pitch, and the discharge pressure pulsations of the two pumps interfere with each other and cancel each other, so that the discharge pressure pulsation is greatly reduced, and the discharge pressure pulsation is reduced. Noise and vibration due to pulsation are greatly reduced.

On the other hand, as in claim 7, two discharge ports for discharging fuel in the pump chamber are formed.
The discharge pressure pulsations at the discharge ports may be combined so that the phases of the discharge pressure pulsations are shifted by about a half wavelength and interfere with each other.

More specifically, the start position of the upstream discharge port of the two discharge ports is set near the end of the pump chamber where the volume is maximum, and the upstream discharge port is set to the upstream discharge port. The end position of the port is set near the end of the pump chamber formed when both gears move half-phase, and the start position of the downstream discharge port is set to the end of the first pump chamber formed from the end of the upstream discharge port. It is good to set it near.

With this arrangement, the discharge pressure pulsations of the two discharge ports interfere with each other and cancel each other,
Discharge pressure pulsation is greatly reduced, and noise and vibration due to pressure pulsation are significantly reduced. As a result, the number of parts can be reduced and the configuration can be simplified as compared with the case where two pumps are provided, and a reduction in size, weight, and cost can be realized.

In this case, a communication groove extending in the rotational direction from the upstream discharge port of the two discharge ports is provided, and the pump chamber that has passed through the upstream discharge port is connected to the communication groove. May be configured to communicate with the upstream discharge port. With this configuration, a part of the fuel pressurized in the pump chamber after passing through the upstream discharge port flows backward through the communication groove and flows into the upstream discharge port. As a result, in the upstream discharge port, two pressure pulsations of different phases discharged from the two adjacent pump chambers interfere with each other, and the discharge pressure pulsation of the upstream discharge port is reduced by the interference effect. .

Further, it is preferable that the length of the communication groove in the rotational direction is set so that the communication groove communicates with the pump chamber for discharging fuel to the downstream discharge port.
With this configuration, the upstream discharge port and the downstream discharge port communicate with each other via the communication groove and the pump chamber. Therefore, in the downstream discharge port, the pump chamber that discharges fuel to the downstream discharge port is used. With respect to the discharge pressure pulsation, the pressure pulsation whose phase propagating from the upstream discharge port through the communication groove portion and the pump chamber is shifted by about a half wavelength interferes, and the interference effect of the downstream discharge port due to the interference effect. Discharge pressure pulsation is reduced. In this way, in a state where the discharge pressure pulsations of the two discharge ports are both reduced, the discharge pressure pulsations of the two discharge ports are merged while interfering with each other in the flow path outside the pump unit with a shift of about a half wavelength. Therefore, the discharge pressure pulsation of the entire fuel pump can be reduced more effectively.

In order to achieve the second object, an eleventh aspect of the present invention is an independent form of the configuration defined in the third aspect.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [Embodiment (1)] An embodiment (1) of the present invention will be described below with reference to FIGS.
Here, FIG. 1 is a longitudinal sectional view showing a cutaway pump section 12 of the fuel pump, FIG. 2 is a sectional view taken along line DD of FIG. 3, FIG. 3 is a bottom view of the fuel pump, and FIG. B sectional view, FIG. 5 is FIG.
6 is a sectional view taken along the line AA in FIG.

First, the configuration of the entire trochoid gear type fuel pump will be schematically described with reference to FIG. A trochoid gear type pump section 12 and a motor section 13 are assembled in a cylindrical housing 11 of a fuel pump. At one end (lower end) of the housing 11, a pump cover 14 that covers the lower surface of the pump section 12 is fixed by caulking or the like, and a fuel inlet 15 formed in the pump cover 14 is formed.
Then, fuel in a fuel tank (not shown) is sucked into the pump unit 12. A motor cover 16 that covers the motor unit 13 is fixed to the other end (upper end) of the housing 11 by caulking or the like.
3 are provided with a connector 17 for supplying electricity to the fuel cell 3 and a fuel discharge port 18. The fuel discharged from the pump unit 12 is
The fuel is discharged from the fuel discharge port 18 through a gap between the armature 33 of the motor unit 13 and the magnet 38.

Next, the structure of the trochoid gear pump 12 will be described with reference to FIGS. Pump section 12
Is formed by closing the upper and lower openings of a cylindrical casing 21 with a casing cover 22 and an inner side cover 23, and these parts are fixed together with the pump cover 14 in the housing 11 by screwing or the like. An inner cover 23 is sandwiched between the cover 14 and the cylindrical casing 21. One outer gear 24 and two inner gears 25 and 26 are housed in the casing of the pump section 12. The outer gear 24,
The inner gears 25 and 26, the inner side cover 23, and the cylindrical casing 21 are formed of a wear-resistant material such as an iron-based sintered metal, and the inner surface (lower surface) of the casing cover 22 and the inner side cover 23 are formed. A sliding surface such as an inner surface (upper surface) may be subjected to a surface treatment such as a fluororesin coating in order to reduce sliding resistance to each of the gears 24 to 26.

As shown in FIG. 6, on the inner peripheral side of the outer gear 24 and the outer peripheral side of the inner gears 25 and 26, there are formed internal teeth 24a and external teeth 25a and 26a, respectively.
The number of teeth of 4 is an odd number, and the number of teeth of the inner gears 25 and 26 is formed as an even number smaller by one than the number of teeth of the outer gear 24. The tooth thickness of the inner gears 25 and 26 is
4 is formed to be the same as the tooth thickness.

The outer gear 24 is rotatably fitted in a circular hole 27 formed in the cylindrical casing 21.
The thickness dimension (axial dimension) of the outer gear 24 is smaller than the thickness dimension of the cylindrical casing 21 by the side clearance. On the inner peripheral side of the outer gear 24, a partition wall 28 (see FIGS. 1 and 2) that divides a space in the outer gear 24 into two equal parts is formed. This partition wall 28
May be formed integrally with the outer gear 24, or a partition wall 28 formed as a separate component may be fixed to the inner peripheral center portion of the outer gear 24 by joining or the like, or between the two divided outer gears. Alternatively, the outer gear 24 may be formed by interposing a partition wall of another part and integrating these three parts by joining or the like.

On the inner peripheral side of the outer gear 24, two inner gears 25 and 26 are superposed and eccentrically arranged with a partition wall 28 interposed therebetween.
The eccentric directions of 5, 26 are offset by 180 ° from each other. And, the teeth 24a of each gear 24, 25, 26,
Numerous pump chambers 29, 30 (see FIG. 6) are formed between the teeth by engagement or contact of 25a, 26a. In this case, since the inner gears 25 and 26 are eccentric with respect to the outer gear 24, each gear 24,
The operation of continuously increasing / decreasing the amount of engagement of the teeth 24a, 25a, 26a of the teeth 25, 26 and continuously increasing / decreasing the volume of the pump chambers 29, 30 is repeated with one rotation as a cycle.

As shown in FIGS. 1 and 2, the inner gear 2
5 and 26 are the casing cover 22 and the pump cover 14.
Are rotatably fitted to and supported by cylindrical bearings 31 and 32 eccentrically press-fit to the opposite sides of each other at an angle of 180 °, and a rotating shaft 34 of an armature 33 of the motor unit 13 is provided inside the cylindrical bearings 31 and 32. It has been inserted. The D-cut portion of the rotation shaft 34 is inserted into a D-shaped connection hole 35 formed in the center of the partition wall 28 of the outer gear 24, and the rotation shaft 34 of the motor portion 13 and the outer gear 24 are connected so that rotation can be transmitted. .

The rotating shaft 34 of the motor unit 13 and the outer gear 2
The coupling structure with the motor 4 is not limited to the above-described configuration. As shown in FIGS. 8 and 9, the coupling 60 is inserted into the D-cut portion of the rotating shaft 34 of the motor unit 13, and the coupling 6 is inserted.
0 may be inserted into a coupling-shaped coupling hole 61 formed in the center of the partition wall 28 of the outer gear 24 to be driven to rotate.

When the outer gear 24 is driven to rotate by the motor section 13, the inner gears 25 and 26 meshing with the outer gear 24 rotate about cylindrical bearings 31 and 32 eccentric to opposite sides by 180 °. The motor unit 1
3 in the radial direction of the armature 33
4 is supported by being inserted into a radial bearing 36 press-fitted into the center of the casing cover 22.
The load in the thrust direction of No. 3 is supported by a thrust bearing 37 press-fitted inside the center of the pump cover 14.

The fuel sucked from the fuel inlet 15 of the pump cover 14 is divided into two directions and is sucked into the pump chambers 29, 30 of the upper and lower inner gears 25, 26. That is, half of the fuel sucked from the fuel suction port 15 is supplied to the suction port 39 formed in the inner side cover 23 (see FIG. 2).
From the pump chamber 30 of the lower inner gear 26. The remaining half of the fuel sucked from the fuel inlet 15 is supplied to the fuel introduction groove 40 (FIGS.
→ See FIG. 4) → Through hole 41 of internal side cover 23 (FIG. 2)
→) Through the flow path 42 of the cylindrical casing 21 (see FIG. 2) → into the pump chamber 29 of the upper inner gear 25 via the fuel introduction groove 43 (see FIGS. 2 and 5) on the inner surface of the casing cover 22. .

The pump chamber 3 of the lower inner gear 26
The fuel discharged from 0 is discharged from the discharge port 45 of the inner side cover 23 (see FIG. 1) → the discharge groove 47 on the inner surface of the pump cover 14 (see FIGS. 1 and 4) → the discharge channel 48 (see FIG. 1). The liquid is discharged to the motor section 13 through the path. The discharge channel 48 is formed by the inner side cover 23 and the cylindrical casing 21.
And the casing cover 22 is vertically penetrated.

On the other hand, the pump chamber 2 of the upper inner gear 25
9 is discharged from the discharge port 44 of the casing cover 22 (see FIGS. 1 and 5) to the motor unit 13 side.

In the trochoid gear type fuel pump constructed as described above, when the motor 13 rotates and the outer gear 24 and the inner gears 25 and 26 rotate, each gear 2
The engagement amount of the teeth 24a, 25a, 26a of 4, 25, 26 continuously increases and decreases, and each tooth 24a, 25a, 26
The operation of continuously increasing / decreasing the volume of each of the pump chambers 29 and 30 formed between “a” is repeated with one rotation as a cycle.
Thereby, in the pump chambers 29 and 30 whose volumes are expanded,
In the pump chambers 29 and 30 where the fuel is transferred while sucking the fuel and the volume is reduced, the transferred fuel is supplied to the discharge port 4.
Discharge from 4,45.

At this time, in the discharge region where the volumes of the pump chambers 29 and 30 decrease, the fuel in the pump chambers 29 and 30 is pressurized and the fuel pressure (fuel pressure) rises. Load is applied in the outer diameter direction. The load in the outer diameter direction due to such a rise in fuel pressure is reduced by the pump chamber 2.
Since the pressure does not occur in the suction region where the fuel pressure of the pump chambers 9 and 30 is reduced, the load on the outer gear 24 in the radial direction is limited to the discharge region (the discharge port 4 where the fuel pressure of the pump chambers 29 and 30 increases).
(4, 45 side) only.

In the present embodiment, the two inner gears 25 and 26 arranged on the inner peripheral side of the outer gear 24 have their eccentric directions deviated by 180 ° from each other, so that the two inner gears 25 and 26 Fuel pressure rising side (discharge port 4
4,45) are shifted 180 ° from each other. As a result, the loads F1, F in the outer radial direction due to the increase in the fuel pressure are applied to the one outer gear 24 from the two inner gears 25, 26.
2 (see FIG. 6) act on opposite sides of each other by 180 °, so that loads F1 and F
2 are balanced, and the eccentric load hardly acts on the outer gear 24. For this reason, the outer gear 2
4 is not strongly pressed against the inner peripheral surface of the cylindrical casing 21, the sliding resistance (friction loss) of the outer gear 24 with respect to the cylindrical casing 21 becomes smaller than before, and the load on the motor unit 13 is reduced accordingly. Power consumption is reduced. In addition, since the fuel is sucked and discharged by the two inner gears 25 and 26 in the outer gear 24, the fuel discharge performance can be effectively improved in combination with the above-described sliding resistance reduction effect.

Generally, in the trochoid gear type fuel pump, the number of teeth of the inner gears 25 and 26 may be one less than the number of teeth of the outer gear 24.
4 is an even number (the number of teeth of the driven inner gears 25 and 26 is an odd number), the two driven inner gears 25 and 2
6 have the same rotational phase. In this state, the phases of the pulsation waves of the discharge pressure of the two driven inner gears 25 and 26 match, and the pulsation wave of the discharge pressure of one of the inner gears has a peak (valley).
At the time of the other, the other also becomes a peak (valley), two inner gears 2
The discharge pressure pulsations 5 and 26 amplify each other, and noise and vibration due to the discharge pressure pulsation increase.

As a countermeasure against this, in this embodiment (1),
The number of teeth of the outer gear 24 on the driving side is an odd number, and the number of teeth of the inner gears 25 and 26 on the driven side is an even number that is one less than the number of teeth of the outer gear 24 on the driving side. As a result, the rotational phases of the two driven inner gears 25 and 26 are shifted by a half pitch, and the phases of the pulsation waves of the discharge pressure of the two driven inner gears 25 and 26 are shifted by a half cycle of the pulsation wave. As a result, when the discharge pressure pulsation wave of one of the inner gears has a peak, the other becomes a valley, and the discharge pressure pulsations of the two inner gears 25 and 26 interfere with each other and cancel each other, thereby greatly reducing the discharge pressure pulsation. As a result, noise and vibration due to discharge pressure pulsation are significantly reduced. This eliminates the need for conventional noise countermeasures (e.g., a discharge pressure pulsation reduction device and a sound insulating material), and realizes low noise and low vibration at low cost.

When manufacturing the outer gear, a 2
A partition wall of another part may be interposed between the two divided outer gears, and these three parts may be integrated by joining or the like. In this case, however, one of the divided outer gears is half of the other divided outer gear. The partition walls may be sandwiched in a state shifted in pitch to be integrated. In this case, contrary to the above embodiment, the number of teeth of the outer gear is set to an even number, and the number of teeth of the inner gear is set to be one less than the number of teeth of the outer gear.
It is better to use an odd number. Thus, as in the above embodiment, the phases of the pulsation waves of the discharge pressures of the two inner gears are shifted by a half cycle of the pulsation waves, and the pressure pulsation is greatly reduced.

[Embodiment (2)] The pump section 12 of the embodiment (1) is arranged such that two inner gears 25 and 26 are overlapped on the inner peripheral side of one outer gear 24 with a partition wall 28 interposed therebetween. By doing so, two pumps were formed, and the outer gears 24 of the two pumps were formed integrally.
To the pump unit 6 according to the embodiment (2) of the present invention shown in FIG.
Reference numeral 2 denotes an outer gear 67 (68) of two pumps formed separately, and two pumps each having one inner gear 69 (70) arranged on the inner peripheral side of each outer gear 67 (68) are arranged so as to overlap each other. ing.

Hereinafter, the configuration of the pump section 62 will be specifically described. Here, FIG. 10 shows the pump section 62 of the fuel pump.
FIG. 11 is a sectional view taken along line FF of FIG. 10, FIG. 12 is a sectional view taken along line GG of FIG. 10, FIG. 13 is a sectional view taken along line HH of FIG. 10, and FIG. FIG. 2 is a sectional view taken along line II of FIG.
However, portions substantially the same as those in the embodiment (1) will be denoted by the same reference numerals and description thereof will be simplified.

In this embodiment (2), as shown in FIG. 10, the casing of the pump section 62 is formed by stacking two cylindrical casings 63 and 64 with an intermediate plate 65 interposed therebetween.
The upper and lower openings are closed by a casing cover 22 and an inner side cover 23, and these components are fixed together with the pump cover 14 in the housing 11 by screws 66. A pair of outer gear 67 and inner gear 69 constituting the first pump is housed in a space above the intermediate plate 65 in the casing of the pump portion 62, and a second pump is placed in a space below the intermediate plate 65. A pair of outer gear 68 and inner gear 7
0 is stored.

As shown in FIGS. 13 and 14, circular holes 71 and 72 are formed in the cylindrical casings 63 and 64 at positions eccentric to opposite sides by 180 °, respectively.
Outer gears 67 and 68 are rotatably fitted in the gears 1 and 72, respectively. Inner gears 69 and 70 are eccentrically arranged on the inner peripheral side of the outer gears 67 and 68, respectively. In the embodiment (2), the two inner gears 69, 7
0 are arranged coaxially and rotationally driven in the same phase, and each outer gear 6
The eccentric directions of 7, 68 are offset by 180 ° from each other. The number of teeth of the drive-side inner gears 69 and 70 rotated by the motor unit 13 is odd, and the number of teeth of the driven-side outer gears 67 and 68 is equal to the number of teeth of the drive-side inner gear 6.
It is formed in an even number one more than the number of teeth of 9,70.

As shown in FIG. 10, each inner gear 69,
70 is rotatably fitted to and supported by a shaft 73 press-fitted into the center of the pump cover 14.
70 and the rotating shaft 34 of the motor unit 13
4 so as to be able to transmit rotation. Motor unit 1
The rotation shaft 34 and the coupling 74 are connected by inserting the D-cut portion of the third rotation shaft 34 into the D-shaped connection hole formed in the upper portion of the coupling 74, and formed downward at the lower portion of the coupling 74. The coupling 74 and the inner gears 69 and 70 are connected by inserting the plurality of connecting pins 91 into the connection holes of the inner gears 69 and 70. When the inner gears 69, 70 are driven to rotate by the motor section 13, the outer gears 67, 68 meshing with the respective inner gears 69, 70 rotate in a state of being eccentric to 180 ° opposite sides. The load in the thrust direction of the armature 33 of the motor unit 13 is supported on the upper surface of the shaft 73.

As in the embodiment (1), half of the fuel sucked from the fuel suction port 15 of the pump cover 14 is drawn from the suction port 39 of the inner side cover 23 into the pump chamber 76 of the lower inner gear 70. Is done. The remaining half of the fuel sucked from the fuel inlet 15 is supplied to the fuel introduction groove 40 (see FIGS. 10 and 11) on the inner surface of the pump cover 14 → the through flow channel 77 (see FIGS. 10, 13 and 14).
→ The fuel introduction groove 43 on the inner surface of the casing cover 22 (FIG. 10)
And the pump chamber 75 of the upper inner gear 69 through the path shown in FIG. In addition, the through flow path 77 includes the inner side cover 23, the cylindrical casing 64, and the intermediate plate 6.
5 and the cylindrical casing cover 63 are vertically penetrated.

The pump chamber 7 of the lower inner gear 70
The fuel discharged from the motor unit 13 flows through a discharge port 45 of the inner side cover 23 → a discharge groove 47 (see FIG. 11) on the inner surface of the pump cover 14 → a discharge passage 78 (see FIGS. 12 to 14). Is discharged to the side. Note that the discharge channel 78
Is formed so as to penetrate the inner side cover 23, the cylindrical casing 64, the intermediate plate 65, the cylindrical casing 63, and the casing cover 22 in the vertical direction. On the other hand, the fuel discharged from the pump chamber 75 of the upper inner gear 69 is discharged from the discharge port 44 (see FIG. 12) of the casing cover 22 to the motor section 13 side.

In the above-described embodiment (2), the number of teeth of the drive-side inner gears 69 and 70 that are rotated and driven in the same phase by the motor unit 13 is an odd number, and the number of teeth of the driven-side outer gears 67 and 68 is Since the number of teeth of the inner gears 69 and 70 is set to an even number which is one more than the number of teeth, the rotational phases of the two outer gears 67 and 68 on the driven side are shifted by a half pitch, and the discharge pressures of the two pumps are the same as in the embodiment (1). The pulsations interfere with each other and cancel each other, so that the discharge pressure pulsation is greatly reduced, and the noise and vibration due to the discharge pressure pulsation are significantly reduced. This eliminates the need for conventional noise countermeasures (e.g., a discharge pressure pulsation reduction device and a sound insulating material), and realizes low noise and low vibration at low cost.

It should be noted that one inner gear may be rotated with a half pitch shift with respect to the other inner gear. In this case, contrary to the embodiment (2), the inner gears 69 and 70 on the drive side are rotated. The number of teeth is preferably an even number, and the number of teeth of the driven outer gears 67 and 68 is preferably an odd number that is one more than the number of teeth of the inner gears 69 and 70. Accordingly, as in the embodiment (2), the phases of the pulsation waves of the discharge pressures of the two pumps are shifted by a half wavelength (half cycle) of the pulsation waves, and the discharge pressure pulsation is greatly reduced.

In the above embodiment (2), the eccentric directions of the outer gears 67 and 68 of the upper and lower pumps are 180
Due to the shift to the opposite side, the fuel pressure rise side between both pumps is shifted to the opposite side by 180 °. For this reason, the loads in the outer diameter direction act on the opposite sides of each other by 180 ° between the two pumps, so that the loads acting in the outer diameter direction can be balanced as a whole of the fuel pump, and the vibration of the fuel pump can be reduced. .

Further, in the above embodiment (2), the intermediate plate 65 fixed between the two cylindrical casings 63, 64 is interposed between the upper and lower pumps, so that the upper and lower pumps (the outer gear 67, Outer gears 67, 68 due to a radial load (fuel pressure) acting on the outer gears 67, 68).
The tilting of the outer gears 67 and 68 due to the tilting of the outer gears 67 and 68 can be prevented.

Further, in the above embodiment (2), even if the tooth thickness of the outer gears 67, 68 and the inner gears 69, 70 is changed, the tooth thickness is absorbed by the change of the thickness of the inner side cover 23, so that the overall pump length is reduced. Can be kept constant, and the pump discharge capacity can be changed by changing the tooth thickness without changing the overall pump length. Therefore, it is possible to cope with various engines having different required discharge capacities by using a fuel pump of a common size, and it is possible to use a common mounting part (a bracket or the like) for the fuel pump.

In the above embodiment (2), the two inner gears 69, 70 are arranged coaxially,
The eccentric directions of the two outer gears 67 and 68 with respect to the eccentric members 9 and 70 are shifted to the opposite sides by 180 ° from each other.
The two outer gears may be arranged coaxially and the eccentric directions of the two inner gears with respect to the outer gear may be shifted by 180 ° from each other. In this case, the side cover is integrated with the side surface of each outer gear, and the side cover and the rotating shaft of the motor unit are connected to each other, so that the two outer gears are rotationally driven together with the side cover by the motor unit in the same phase. The number of teeth of the outer gear on the driving side may be an odd number, and the number of teeth of the inner gear on the driven side may be an even number one less than the number of teeth of the outer gear. Further, one outer gear may be rotated with a half pitch shift with respect to the other outer gear. In this case, the number of teeth of the outer gear is an even number, and the number of teeth of the inner gear is an odd number which is one less than the number of teeth of the outer gear. It is good.

[Embodiment (3)] Next, FIGS.
Embodiment 9 (3) of the present invention will be described with reference to FIG. Here, FIG. 15 is a longitudinal sectional view showing a cutaway pump section 79 of the fuel pump, FIG. 16 is a JJ sectional view of FIG. 15, FIG. 17 is a KK sectional view of FIG. 15, and FIG. LL sectional view of
FIG. 19 is a cross-sectional view of the casing cover 22 shown along the line MM in FIG. However, portions substantially the same as those in the embodiment (1) will be denoted by the same reference numerals and description thereof will be simplified.

In the present embodiment (3), as shown in FIG.
The upper and lower openings are closed by a casing cover 22 and a pump cover 14. A pair of outer gear 80 and inner gear 81 are housed in the casing of the pump section 79. The outer gear 80 is a cylindrical casing 2
The inner gear 8 is rotatably fitted in the first circular hole 27.
1 is fitted and supported on a rotating shaft 34 of the motor unit 13. The rotation shaft 34 of the motor unit 13 and the inner gear 81 are connected so as to be able to transmit rotation via a coupling 82, and when the inner gear 81 is driven to rotate by the motor unit 13,
The outer gear 80 meshing with the inner gear 81 rotates.

As shown in FIG. 16, a suction port 84 is formed in the pump cover 14 so as to communicate with a plurality of pump chambers 83 whose capacity is increased. From the pump chamber 83.

On the other hand, as shown in FIGS. 17 to 19, the casing chamber 22 has a pump chamber 83 having a reduced volume.
Two discharge ports 85 and 86 are formed so as to communicate with the fuel cell. Fuel discharged from the pump chamber 83 is discharged from the discharge ports 85 and 86 to the motor unit 13 side. By providing each of the discharge ports 85 and 86 as described below, the phases of the discharge pressure pulsations are shifted by about a half wavelength and merged while interfering.

FIG. 17A shows the rotational positions of the inner gear 81 and the outer gear 80 when the volume of the pump chamber 83a at the boundary region between the suction region and the discharge region is maximized.
FIG. 17B shows the inner gear 8 from the position shown in FIG.
1 shows a state when the outer gear 80 and the outer gear 80 are rotated by a half pitch. As shown in FIG. 17A, the first discharge port 85 (upstream discharge port) has a length substantially half a pitch from the partition position between the pump chamber 83a having the maximum volume and the pump chamber 83b adjacent thereto. It is formed over. As a result, as shown in FIG. 17A, the start position of the first discharge port 85 is near the end of the pump chamber 83a where the volume is maximum, and as shown in FIG. The end position of the eye discharge port 85 is near the end of the pump chamber 83a formed when the two gears 80 and 81 have moved half a phase.

Further, the second discharge port 86 (downstream discharge port) is approximately 1.5 times from the first discharge port 85.
It is formed at a position separated by a pitch in the rotation direction.
Thus, as shown in FIG. 17B, the start position of the second discharge port 86 is near the end of the first pump chamber 83b formed from the end of the first discharge port 85, After the first discharge port 85 starts to open to the pump chamber 83a having the maximum volume, the second discharge port 86 starts opening to the pump chamber 83b next to the pump chamber 83a having the maximum volume with a delay of a half pitch. It has become.

As a result, the second discharge is delayed by a half pitch after a part of the fuel in the pump chamber 83a having the maximum volume shown in FIG. The remaining fuel in the pump chamber 83b next to the pump chamber 83a having the maximum capacity is discharged from the port 86. As a result, the vertical timing of the discharge pressure of the two discharge ports 85 and 86 is shifted by a half pitch, and the phase of the discharge pressure pulsation of the two discharge ports 85 and 86 is shifted by a substantially half wavelength.

The interval between the two discharge ports 85 and 86 may be determined according to the number of teeth of the inner gear 81 and the outer gear 80. Even if the number of teeth changes, one pump chamber is provided after the first discharge port. The second discharge port may be formed at a position where (interdental chamber) can be formed.

Further, as shown in FIG.
A recess 87 having a predetermined step (for example, about 0.2 mm) with respect to the lower surface (sliding surface) 22a of the casing cover 22 is formed between the casings 5 and 86. Further, a tapered portion 88 that expands toward the pump chamber 83 is formed at the inlet of the discharge port 86.

In the embodiment (3) described above, the discharge ports 85 and 86 through which the fuel in the pump chamber 83 is discharged.
Are formed such that the phases of the discharge pressure pulsations are shifted by about a half wavelength and merge while interfering with each other.
5, 86 discharge pressure pulsations interfere with each other and cancel each other, so that discharge pressure pulsations are greatly reduced, and noise and vibration due to discharge pressure pulsations are significantly reduced. This makes it possible to reduce the number of parts and simplify the configuration, as compared with the case where two pumps are provided to reduce the discharge pressure pulsation as in the above-described embodiments (1) and (2). Lighter weight and lower cost can be achieved while realizing noise reduction and vibration reduction.

[Embodiment (4)] Next, an embodiment (4) of the present invention will be described with reference to FIGS. Here, FIG. 20 is a longitudinal sectional view showing a cutaway pump section 90 of the fuel pump, FIG. 21 is an NN sectional view of FIG. 20, FIG. 22 is a PP sectional view of FIG. 20, and FIG. QQ sectional view of
24 is a sectional view taken along line RR of FIG. 20, and FIG.
FIG. 8 is a view for explaining positions of forming 8, 99 and a communication groove 100; It is to be noted that the same parts as those in the embodiment (1) are denoted by the same reference numerals, and the description is simplified.

In the present embodiment (4), as shown in FIG.
The upper and lower openings of the pump unit 90 are closed by a casing cover 22 and an inner side cover 23. A pair of outer gear 92 and inner gear 9
3 are stored. The inner gear 93 is rotatably fitted to and supported by a radial bearing 36 press-fitted into the casing cover 22, and the motor portion 13 is provided inside the radial bearing 36.
Of the rotary shaft 34 is inserted. In the present embodiment (4), as shown in FIG.
Thus, the number of teeth of the inner gear 93 is 5.

As shown in FIG. 21, the D-cut portion of the rotating shaft 34 is inserted into the coupling 94, and the coupling 94 is inserted into the coupling-shaped coupling hole 95 formed at the center of the inner gear 93. The motor unit 13
The rotation shaft 34 and the inner gear 93 are connected via a coupling 94 so that rotation can be transmitted.

As shown in FIG. 22, a suction port 97 is formed in the inner side cover 23, and fuel sucked from the fuel suction port 15 is sucked into the pump chamber 96 from the suction port 97.

On the other hand, as shown in FIGS. 23 to 25, the casing cover 22 has a pump chamber 96 having a reduced volume.
Two discharge ports 98 and 99 are formed so as to communicate with the fuel cell. Fuel discharged from the pump chamber 96 is discharged from the discharge ports 98 and 99 to the motor unit 13 side.

FIG. 25A shows the rotational positions of the inner gear 93 and the outer gear 92 when the volume of the pump chamber 96a at the boundary between the suction area and the discharge area is maximized.
FIG. 25B shows the inner gear 9 from the position shown in FIG.
3 shows a state when the outer gear 92 and the outer gear 92 are rotated by a half pitch. In this embodiment (4), as in the embodiment (3), the upstream-side discharge port 98 is provided as shown in FIG.
As shown in (a), a pump chamber 96a having the maximum capacity and a pump chamber 96b adjacent to the pump chamber 96b are formed over a length substantially equal to a half pitch from the partition position.
It is formed at a position away from the upstream discharge port 98 by about 1.5 pitches in the rotation direction. As a result, FIG.
After a part of the fuel in the pump chamber 96a having the maximum volume shown in FIG. 5 (a) is started to be discharged from the upstream discharge port 98, the pump chamber 96a having the maximum volume is discharged from the downstream discharge port 99 with a delay of almost a half pitch. The remaining fuel in the adjacent pump chamber 96b is discharged, and the phases of the discharge pressure pulsations of the two discharge ports 98 and 99 are shifted from each other by almost a half wavelength and merge while interfering.

In this embodiment (4), each discharge port 9
The entirety of the discharge ports 98, 99 is formed in a substantially rectangular shape without narrowing the upstream and downstream ends of the pumps 8, 99, so that the opening area of the discharge ports 98, 99 with respect to the pump chamber 96 can be increased. .

The casing cover 22 has a predetermined step (for example, 0.1
mm) with the upstream discharge port 98
Is formed so as to extend in the rotational direction from the downstream end of the. Thereby, as shown in FIG. 25B, the pump chamber 96b that has passed through the upstream discharge port 98 is connected to the upstream discharge port 98 by the communication groove 100. When the pump chamber 96b moves a half pitch from the position shown in FIG. 25A to reach the position shown in FIG. 25B, the pump chamber 96b starts to communicate with the downstream discharge port 99, Further, when the position moves by a half pitch from the position shown in FIG. 25B, it moves to the position of the pump chamber 96c shown in FIG.

In this case, the length of the communication groove 100 in the rotation direction is such that the leading end of the communication groove 100 is the downstream discharge port 9.
9 is set to communicate with a pump chamber 96c that discharges fuel. Thus, at the rotation position shown in FIG. 25A, the upstream discharge port 98 and the downstream discharge port 99 are connected to each other via the communication groove 100 and the pump chamber 96c.

In the pump section 90 configured as described above,
After the fuel in the pump chamber 96a shown in FIG. 25A starts to be discharged from the upstream discharge port 98, the fuel in the pump chamber 96b shown in FIG. From the two discharge ports 9
The phases of the 8,99 discharge pressure pulsations merge while interfering with a phase shift of approximately half a wavelength.

At this time, as shown in FIG. 25 (b), a part of the fuel pressurized in the pump chamber 96b which has passed through the upstream discharge port 98 flows back through the communication groove 100, and the upstream discharge port It flows into 98. As a result, in the upstream discharge port 98, two pressure pulsations of different phases discharged from the two adjacent pump chambers 98a and 98b interfere with each other, and the upstream discharge port 98 is caused by the interference effect.
Discharge pressure pulsation is reduced.

Further, as shown in FIG. 25 (a), the communication groove 100 is formed so as to communicate with the pump chamber 96c for discharging fuel to the downstream discharge port 99. The side discharge port 99 is communicated with the communication groove 100 via the pump chamber 96c. Thus, the downstream discharge port 99 is connected to the downstream discharge port 9.
9, a discharge pressure pulsation of the pump chamber 96c for discharging fuel,
The pressure pulsation propagating from the upstream discharge port 98 through the communication groove 100 and the pump chamber 96c interferes. As described above, since the pressure pulsation propagating from the upstream discharge port 98 is advanced by approximately half a wavelength from the discharge pressure pulsation of the downstream discharge port 99, the interference of the two pressure pulsations causes the downstream pulsation of the downstream discharge port 99 to generate. The discharge pressure pulsation is effectively reduced.

Therefore, in the present embodiment (4), the communication groove 100 reduces both the discharge pressure pulsation of the upstream discharge port 98 and the discharge pressure pulsation of the downstream discharge port 99, and the two discharge ports 98 , 99 are merged while interfering with each other in the flow path outside the pump section 90 with a shift of almost half a wavelength, and the effect of reducing the discharge pressure pulsation of the whole pump can be further improved. Noise and vibration caused by the vibration can be effectively reduced.

In this embodiment (4), the communication groove 10
The length of the communication groove 100 is set so that the communication groove 100 communicates with the pump chamber 96c that discharges fuel to the downstream discharge port 99. However, the length of the communication groove 100 is shortened to reduce the length of the pump chamber 96c. May not be reached. Even in this case, the effect of reducing the discharge pressure pulsation of the upstream discharge port 98 by the communication groove 100 can be obtained.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a fuel pump according to an embodiment (1) of the present invention in a cutaway manner.

FIG. 2 is a sectional view taken along line DD of FIG. 3;

FIG. 3 is a bottom view of the fuel pump.

FIG. 4 is a sectional view taken along line BB of FIG. 2;

FIG. 5 is a sectional view taken along line CC of FIG. 2;

FIG. 6 is a sectional view taken along line AA of FIG. 1;

FIG. 7 is a diagram illustrating the structure of a conventional trochoid gear type fuel pump.

FIG. 8 is a longitudinal sectional view showing a pump section of a fuel pump according to a modification of the embodiment (1) of the present invention in a cutaway manner.

FIG. 9 is a sectional view taken along line EE of FIG. 8;

FIG. 10 is a vertical cross-sectional view showing a pump section of a fuel pump according to an embodiment (2) of the present invention in a cutaway manner.

11 is a sectional view taken along line FF of FIG. 10;

FIG. 12 is a sectional view taken along line GG of FIG. 10;

FIG. 13 is a sectional view taken along line HH of FIG. 10;

FIG. 14 is a sectional view taken along the line II of FIG. 10;

FIG. 15 is a longitudinal sectional view showing a pump section of the fuel pump according to the embodiment (3) of the present invention, which is cut away.

16 is a sectional view taken along the line JJ of FIG.

17A and 17B are views for explaining a formation position of a discharge port, and FIGS. 17A and 17B are cross-sectional views taken along the line KK of FIG.

18 is a sectional view taken along line LL of FIG.

FIG. 19 is a sectional view of the casing cover shown along the line MM in FIG. 18;

FIG. 20 is a longitudinal sectional view showing a pump section of a fuel pump according to an embodiment (4) of the present invention in a cutaway manner.

21 is a sectional view taken along line NN of FIG. 20;

FIG. 22 is a sectional view taken along line PP of FIG. 20;

FIG. 23 is a sectional view taken along line QQ of FIG. 20;

FIG. 24 is a sectional view taken along line RR of FIG. 20;

FIGS. 25A and 25B are views for explaining formation positions of a discharge port and a communication groove, and FIGS. 25A and 25B are views showing a state of a gear rotation position shifted by a half pitch; FIGS.

[Explanation of symbols]

11 ... housing, 12 ... pump part, 13 ... motor part,
14 pump cover, 15 fuel inlet, 18 fuel outlet, 21 cylindrical casing, 22 casing cover, 23 internal side cover, 24 outer gear, 24
a ... internal teeth, 25, 26 ... inner gear, 25a, 26a ...
External teeth, 28: Partition wall, 29, 30 ... Pump room, 31, 3
2 ... cylindrical bearing, 34 ... rotating shaft, 39 ... suction port, 40
... Fuel introduction groove, 42 ... Through channel, 43 ... Fuel introduction groove, 4
4, 45 discharge port, 47 discharge groove, 48 discharge flow path, 62 pump part, 63, 64 cylindrical casing, 6
5. Intermediate plate, 67, 68 ... Outer gear, 69, 7
0 ... inner gear, 73 ... shaft, 75, 76 ... pump chamber, 77 ... through flow path, 78 ... discharge flow path, 79 ... pump section, 80 ... outer gear, 81 ... inner gear, 83 ... pump chamber, 84 ... suction port, 85, 86 ... discharge port, 9
0: pump part, 92: outer gear, 93: inner gear,
97 ... suction port, 98, 99 ... discharge port, 100 ...
Communication groove.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Katsuhiko Kusaya 1-1-1 Showa-cho, Kariya-shi, Aichi F-term in DENSO Corporation (reference) 3H041 AA02 BB04 CC11 DD01 DD05 DD06 DD07 DD10 DD13 DD18 DD36 DD38 3H044 AA02 BB03 CC11 DD01 DD05 DD06 DD13 DD16 DD18 DD26 DD28

Claims (11)

[Claims] An inner gear with external teeth is eccentrically arranged on the inner peripheral side of an outer gear with internal teeth, and a pump chamber formed between the teeth of both gears by meshing both gears is rotated by rotation of both gears. In the fuel pump that sucks and discharges fuel by continuously increasing and decreasing the volume of the pump chamber while moving the pump chamber in the
And a fuel pump wherein the phases of the discharge pressure pulsations of these two pumps merge while interfering with each other with a phase shift of approximately half a wavelength. 2. The fuel pump according to claim 1, wherein the rotation phases of the two pumps are shifted by approximately a half pitch. 3. The two outer gears of the two pumps are integrally formed, and two inner gears are eccentrically arranged on the inner peripheral side of one outer gear with a partition wall interposed therebetween, and both inner gears with respect to the outer gear are arranged. 3. The fuel pump according to claim 1, wherein the eccentric directions are shifted by 180 degrees from each other. 4. An outer gear of the two pumps is formed separately, and two pumps having one inner gear eccentrically arranged on the inner peripheral side of each outer gear are arranged so as to overlap with each other. 3. The fuel pump according to claim 1, wherein the eccentric directions are shifted by 180 degrees from each other. 5. The outer gears of the two pumps are rotationally driven by a motor in the same phase, the number of teeth of the outer gear is odd, and the number of teeth of the inner gear driven by the outer gear is smaller than the number of teeth of the outer gear. The fuel pump according to claim 3 or 4, wherein the number is one less than an even number. 6. The inner gears of the two pumps are driven to rotate in the same phase by a motor, the number of teeth of the inner gear is odd, and the number of teeth of the outer gear driven by the inner gear is smaller than the number of teeth of the inner gear. 5. The fuel pump according to claim 4, wherein the number is set to an even number greater by one. 7. An inner gear with external teeth is eccentrically arranged on the inner peripheral side of an outer gear with internal teeth, and a pump chamber formed between the teeth of both gears by meshing both gears is rotated by rotation of both gears. In a fuel pump that sucks and discharges fuel by continuously increasing and decreasing the volume of the pump chamber while moving in the direction, two discharge ports for discharging fuel in the pump chamber are formed at two locations. A fuel pump characterized in that the discharge pressure pulsations of the discharge ports at the locations are merged while interfering with each other with a phase shifted by about a half wavelength. 8. The start position of the upstream discharge port of the two discharge ports is set near the end of the pump chamber where the volume is maximum, and the end position of the upstream discharge port is determined by both gears. The start position of the downstream discharge port is set near the end of the first pump chamber formed from the end portion of the upstream discharge port. The fuel pump according to claim 7, wherein 9. A communication groove portion extending in a rotational direction from an upstream discharge port of the two discharge ports is provided, and a pump chamber that has passed through the upstream discharge port is formed by the communication groove portion with the upstream discharge port. The fuel pump according to claim 7, wherein the fuel pump is configured to communicate with the fuel pump. 10. The communication groove according to claim 9, wherein a length of the communication groove in a rotational direction is set such that the communication groove communicates with a pump chamber that discharges fuel to a downstream discharge port. Fuel pump. 11. An inner gear with external teeth is eccentrically arranged on the inner peripheral side of an outer gear with internal teeth, and a pump chamber formed between the teeth of both gears by meshing both gears is rotated by rotation of both gears. In a fuel pump that sucks and discharges fuel by continuously increasing and decreasing the volume of the pump chamber while moving in the direction, two inner gears are overlapped on the inner peripheral side of one outer gear with a partition wall interposed therebetween. And the eccentric directions of both inner gears with respect to the outer gear are set to one another.
A fuel pump characterized in that the fuel pump is shifted to the opposite side by 80 °.