JP4332772B2 - Fuel pump - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a trochoid gear type fuel pump configured by eccentrically arranging an inner gear on the inner peripheral side of an outer gear.
[0002]
[Prior art]
In recent years, in order to improve the fuel discharge performance of a fuel pump mounted on a vehicle, it has been studied to adopt a trochoid gear type fuel pump. In this trochoid gear type fuel pump, as shown in FIG. 7, an inner gear 3 with external teeth is eccentrically arranged on the inner peripheral side of an outer gear 2 with internal teeth rotatably accommodated in a cylindrical pump casing 1. At the same time, the gears 2 and 3 are meshed to form a pump chamber 4 between the teeth of the two gears 2 and 3, and the inner gear 3 is rotationally driven by a drive motor (not shown) to rotate the outer gear 2. While moving the pump chamber 4 between the teeth of the two gears 2 and 3 in the rotational direction, the volume of the pump chamber 4 is continuously increased and decreased to suck and discharge fuel.
[0003]
[Problems to be solved by the invention]
Since such a trochoid gear type fuel pump repeatedly changes the volume of the pump chamber 4, a discharge pressure pulsation having a frequency corresponding to the number of teeth of the inner gear 3 is generated, and the discharge pressure pulsation causes a fuel tank, a fuel pipe, a vehicle There is a disadvantage that noise and vibration are increased by vibrating the floor panel. For this reason, when using a trochoid gear type fuel pump, noise reduction measures such as mounting a discharge pressure pulsation reducing device outside the fuel pump or attaching a sound insulation to the vehicle body to reduce noise and vibration There is a disadvantage that the cost increases.
[0004]
By the way, the trochoid gear type fuel pump is a region where the volume of the pump chamber 4 decreases after the fuel is sucked into the pump chamber 4 in the region where the volume of the pump chamber 4 increases due to the rotation of both gears 2 and 3. The pressure in the pump chamber 4 is increased and discharged. At this time, in the discharge region where the volume of the pump chamber 4 decreases, the fuel in the pump chamber 4 is pressurized and the fuel pressure (fuel pressure) rises, so that the outer gear 2 is subjected to a load in the outer diameter direction due to the increase in fuel pressure. . Since the load in the outer diameter direction due to the increase in the fuel pressure does not occur in the suction region (suction port side) where the fuel pressure in the pump chamber 4 decreases, the load in the outer diameter direction on the outer gear 2 is caused by the fuel pressure in the pump chamber 4. This works only in the ascending discharge region (discharge port side), and this becomes an unbalanced load, and a part of the outer gear 2 on the discharge port side is pressed strongly 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 of the drive motor increases, resulting in an increase in power consumption and a decrease in fuel discharge performance (pump rotation speed Has the disadvantage of incurring a decrease.
[0005]
  The present invention has been made in consideration of these circumstances,The present inventionThe purpose of this is to provide a fuel pump that can reduce noise and vibration due to pulsation of discharge pressure at low cost.The
[0014]
[Means for Solving the Problems]
  In the invention according to claim 1, an inner gear with outer teeth is arranged eccentrically on the inner peripheral side of the outer gear with inner teeth, and a pump chamber formed between the teeth of both gears by engaging both gears is provided. The pump chamber is configured to continuously increase / decrease the volume of the pump chamber while moving in the rotational direction by rotation to suck and discharge fuel, andTwo discharge ports for discharging fuel in the pump chamber are formed at two locations, and the phases of the discharge pressure pulsations of these two discharge ports are shifted by approximately a half wavelength and merged while interfering with each other.The fuel pump is configured as follows.
[0015]
  The present inventionThe start position of the upstream discharge port of the two discharge ports is set in the vicinity of the end of the pump chamber where the volume is maximum, and the end position of the upstream discharge port is moved by a half-phase movement of both gears. Set near the end of the pump chamber to be formed, and set the start position of the downstream discharge port near the end of the first pump chamber formed from the end of the upstream discharge portIt is characterized by that.
[0016]
If it does in this way, the discharge pressure pulsation of two discharge ports will mutually interfere and cancel each other out, the discharge pressure pulsation will be reduced significantly, and the noise and vibration by pressure pulsation will be reduced significantly. Thereby, compared with the case where two pumps are provided, the number of parts can be reduced and the configuration can be simplified, and a reduction in size, weight, and cost can be realized.
[0017]
  In this case, the claim2As described above, a communication groove extending in the rotation 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 communicates with the upstream discharge port through the communication groove. You may comprise. In this way, part of the fuel pressurized in the pump chamber that has passed through the upstream discharge port flows back into the communication groove and flows into the upstream discharge port. Thereby, in the upstream discharge port, two pressure pulsations out of phase discharged from two adjacent pump chambers interfere with each other, and the discharge pressure pulsation in the upstream discharge port is reduced by the interference effect. .
[0018]
  Further claims3As described above, the length of the communication groove portion in the rotation direction may be set so that the communication groove portion communicates with the pump chamber that discharges fuel to the downstream discharge port. In this way, 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. The pressure pulsation in which the phase propagating from the upstream discharge port through the communication groove and the pump chamber is shifted by approximately half wavelength will interfere with the discharge pressure pulsation of the upstream discharge port. Discharge pressure pulsation is reduced. In this manner, in a state where both the discharge pressure pulsations of the two discharge ports are reduced, the discharge pressure pulsations of these two discharge ports merge while interfering with each other in the flow path outside the pump section with a shift of almost half wavelength. Thus, the discharge pressure pulsation of the entire fuel pump can be further effectively reduced.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
[Embodiment (1)]
Hereinafter, an embodiment (1) of the present invention will be described with reference to FIGS. Here, FIG. 1 is a longitudinal sectional view showing the fuel pump section 12 cut away, FIG. 2 is a sectional view taken along the line DD in FIG. 3, FIG. 3 is a bottom view of the fuel pump, and FIG. B sectional view, FIG. 5 is a CC sectional view of FIG. 2, and FIG. 6 is an AA sectional view of FIG.
[0021]
First, the overall configuration of the trochoid gear type fuel pump will be described with reference to FIG. A trochoid gear type pump unit 12 and a motor unit 13 are assembled in a cylindrical housing 11 of the fuel pump. A pump cover 14 that covers the lower surface of the pump portion 12 is fixed to one end (lower end) of the housing 11 by caulking or the like, and a fuel tank (not shown) in a fuel tank (not shown) is formed from a fuel inlet 15 formed in the pump cover 14. Fuel 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. The motor cover 16 includes a connector 17 and a fuel discharge port 18 for energizing the motor unit 13. Is provided. The fuel discharged from the pump unit 12 is discharged from the fuel discharge port 18 through a gap between the armature 33 of the motor unit 13 and the magnet 38.
[0022]
Next, the configuration of the trochoid gear type pump unit 12 will be described with reference to FIGS. 1 to 6. The casing of the pump unit 12 is configured by closing the upper and lower openings of the cylindrical casing 21 with a casing cover 22 and an internal side cover 23, and these components are fixed in the housing 11 together with the pump cover 14 by screwing or the like. An internal cover 23 is sandwiched between the pump cover 14 and the cylindrical casing 21. One outer gear 24 and two inner gears 25 and 26 are accommodated in the casing of the pump unit 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 iron-based sintered metal, and the inner surface (lower surface) of the casing cover 22 is also formed. The sliding surface such as the inner surface (upper surface) of the inner side cover 23 may be subjected to a surface treatment such as a fluororesin coating in order to reduce sliding resistance with respect to the gears 24 to 26.
[0023]
As shown in FIG. 6, inner teeth 24a and outer teeth 25a, 26a are formed on the inner peripheral side of the outer gear 24 and the outer peripheral sides of the inner gears 25, 26, respectively, and the outer gear 24 has an odd number of teeth. The number of teeth 26 is an even number that is one less than the number of teeth of the outer gear 24. Further, the inner gears 25 and 26 have the same tooth thickness as the outer gear 24.
[0024]
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. A partition wall 28 (see FIGS. 1 and 2) that divides the space in the outer gear 24 into two equal parts is formed on the inner peripheral side of the outer gear 24. The partition wall 28 is formed integrally with the outer gear 24, or the partition wall 28 formed as a separate part is fixed to the inner peripheral central portion of the outer gear 24 by joining or the like, or divided into two A partition wall of another part may be sandwiched between two divided outer gears, and these three parts may be integrated by joining or the like to form the outer gear 24.
[0025]
On the inner peripheral side of the outer gear 24, two inner gears 25, 26 are arranged in an eccentric manner with the partition wall 28 interposed therebetween, and the eccentric directions of the inner gears 25, 26 with respect to the outer gear 24 are shifted 180 ° opposite to each other. Yes. A large number of pump chambers 29, 30 (see FIG. 6) are formed between the teeth 24a, 25a, 26a of the gears 24, 25, 26 by meshing or contacting with each other. In this case, since the inner gears 25 and 26 are eccentric with respect to the outer gear 24, the meshing amounts of the teeth 24a, 25a, and 26a of the gears 24, 25, and 26 are continuously increased / decreased during rotation. The operation of continuously increasing / decreasing the volumes of the chambers 29 and 30 is repeated with one rotation as a cycle.
[0026]
As shown in FIGS. 1 and 2, the inner gears 25 and 26 are rotatably fitted to cylindrical bearings 31 and 32 that are eccentrically inserted 180 ° opposite to each other at substantially the center of the casing cover 22 and the pump cover 14. The rotary shaft 34 of the armature 33 of the motor unit 13 is inserted inside the cylindrical bearings 31 and 32. The D-cut portion of the rotating shaft 34 is inserted into a D-shaped connecting hole 35 formed in the center portion of the partition wall 28 of the outer gear 24, and the rotating shaft 34 of the motor portion 13 and the outer gear 24 are connected so as to transmit rotation. .
[0027]
The connection structure between the rotating shaft 34 of the motor unit 13 and the outer gear 24 is not limited to the above-described configuration. As shown in FIGS. 8 and 9, a coupling 60 is attached to the D-cut portion of the rotating shaft 34 of the motor unit 13. The coupling 60 may be inserted into a coupling-shaped connecting hole 61 formed at the center of the partition wall 28 of the outer gear 24 and driven to rotate.
[0028]
When the outer gear 24 is rotationally driven by the motor unit 13, the inner gears 25 and 26 that mesh with the outer gear 24 rotate around the cylindrical bearings 31 and 32 that are eccentric to each other by 180 °. The radial load of the armature 33 of the motor unit 13 is supported by inserting the rotary shaft 34 through a radial bearing 36 press-fitted into the central portion of the casing cover 22, and the thrust load of the armature 33 is It is supported by a thrust bearing 37 that is press-fitted inside the center of the pump cover 14.
[0029]
The fuel sucked from the fuel suction port 15 of the pump cover 14 is divided into two directions and sucked into the pump chambers 29 and 30 of the inner gears 25 and 26 on both the upper and lower sides. That is, half of the fuel sucked from the fuel suction port 15 is sucked into the pump chamber 30 of the lower inner gear 26 from the suction port 39 (see FIG. 2) formed in the inner side cover 23. The remaining half of the fuel sucked from the fuel inlet 15 is the fuel introduction groove 40 (see FIGS. 2 to 4) on the inner surface of the pump cover 14 → the through hole 41 (see FIG. 2) of the inner side cover 23 → the cylindrical casing. 21 through the passage 42 (see FIG. 2) → the fuel introduction groove 43 (see FIGS. 2 and 5) on the inner surface of the casing cover 22 and sucked into the pump chamber 29 of the upper inner gear 25.
[0030]
Further, the fuel discharged from the pump chamber 30 of the lower inner gear 26 is discharged from the discharge port 45 (see FIG. 1) of the inner side cover 23 → the discharge groove 47 (see FIGS. 1 and 4) on the inner surface of the pump cover 14 → It is discharged to the motor unit 13 side through the path of the discharge flow path 48 (see FIG. 1). The discharge passage 48 is formed so as to penetrate the inner side cover 23, the cylindrical casing 21 and the casing cover 22 in the vertical direction.
[0031]
On the other hand, the fuel discharged from the pump chamber 29 of the upper inner gear 25 is discharged from the discharge port 44 (see FIGS. 1 and 5) of the casing cover 22 to the motor unit 13 side.
[0032]
In the trochoid gear type fuel pump configured as described above, when the motor unit 13 rotates and the outer gear 24 and the inner gears 25 and 26 rotate, the meshing amounts of the teeth 24a, 25a, and 26a of the gears 24, 25, and 26, respectively. Is continuously increased / decreased, and the operation of continuously increasing / decreasing the volume of each pump chamber 29, 30 formed between the teeth 24a, 25a, 26a is repeated with one rotation as a cycle. Thereby, in the pump chambers 29 and 30 whose volume is increased, the fuel is transferred while sucking the fuel, and in the pump chambers 29 and 30 whose volume is reduced, the transferred fuel is discharged from the discharge ports 44 and 45.
[0033]
At this time, in the discharge region in which the volumes of the pump chambers 29 and 30 are reduced, the fuel in the pump chambers 29 and 30 is pressurized and the fuel pressure (fuel pressure) rises. The load is applied. Since the load in the outer diameter direction due to the increase in the fuel pressure does not occur in the suction region where the fuel pressure in the pump chambers 29 and 30 decreases, the load in the outer diameter direction on the outer gear 24 increases the fuel pressure in the pump chambers 29 and 30. Works only in the discharge area (discharge ports 44 and 45 side).
[0034]
In the present embodiment, the two inner gears 25, 26 arranged on the inner peripheral side of the outer gear 24 are offset from each other by 180 ° in the eccentric direction, so the two inner gears 25, 26 are on the fuel pressure increasing side. (Discharge ports 44 and 45) are shifted 180 ° opposite to each other. As a result, the outer radial loads F1 and F2 (see FIG. 6) due to the increase in fuel pressure from the two inner gears 25 and 26 act on the one outer gear 24 on the opposite sides of 180 °, and thus act on the outer gear 24. The loads F1 and F2 in the outer diameter direction are balanced, and the eccentric load hardly acts on the outer gear 24. For this reason, the outer gear 24 is not strongly pressed against the inner peripheral surface of the cylindrical casing 21 by the fuel pressure, and the sliding resistance (friction loss) of the outer gear 24 with respect to the cylindrical casing 21 becomes smaller than that of the conventional one, and accordingly, the motor portion The load of 13 becomes small and power consumption decreases. 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 enhanced in combination with the above-described sliding resistance reduction effect.
[0035]
In general, in the trochoid gear type fuel pump, the number of teeth of the inner gears 25, 26 may be one less than the number of teeth of the outer gear 24, but the number of teeth of the outer gear 24 on the driving side is even (the driven inner gears 25, 26 on the driven side). If the number of teeth is an odd number), the rotational phases of the two driven inner gears 25 and 26 coincide. In this state, the phase of the pulsating wave of the discharge pressure of the two driven inner gears 25 and 26 coincides, and when the discharge pressure pulsating wave of one inner gear is a mountain (valley), the other is also a mountain (valley). The discharge pressure pulsations of the two inner gears 25 and 26 amplify each other, and noise and vibration due to the discharge pressure pulsations increase.
[0036]
As a countermeasure, 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 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-side inner gears 25, 26 are shifted by a half pitch, and the phase of the pulsating wave of the discharge pressure of the two driven-side inner gears 25, 26 is shifted by a half period of the pulsating wave. As a result, when the discharge pressure pulsation wave of one inner gear is 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 out. The noise and vibration due to the discharge pressure pulsation are greatly reduced. This eliminates the need for conventional noise countermeasures (discharge pressure pulsation reduction device, sound insulation material, etc.), and can realize low noise and low vibration at low cost.
[0037]
When manufacturing the outer gear, a partition wall of another part may be sandwiched between two divided outer gears divided in advance, and these three parts may be integrated by joining or the like. The split outer gear may be integrated by sandwiching the partition wall in a state shifted by a half pitch with respect to the other split outer gear. In this case, contrary to the above embodiment, the number of teeth of the outer gear may be an even number, and the number of teeth of the inner gear may be an odd number that is one less than the number of teeth of the outer gear. As a result, as in the above embodiment, the phase of the pulsating wave of the discharge pressure of the two inner gears is shifted by a half cycle of the pulsating wave, and the pressure pulsation is greatly reduced.
[0038]
[Embodiment (2)]
The pump unit 12 of the embodiment (1) constitutes two pumps by arranging two inner gears 25 and 26 on the inner peripheral side of one outer gear 24 with the partition wall 28 interposed therebetween, Although the outer gear 24 of the two pumps is integrally formed, the pump portion 62 of the embodiment (2) of the present invention shown in FIGS. 10 to 14 is formed by separately forming the outer gear 67 (68) of the two pumps. 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.
[0039]
Hereinafter, the configuration of the pump unit 62 will be described in detail. Here, FIG. 10 is a longitudinal sectional view showing the fuel pump part 62 cut away, FIG. 11 is a sectional view taken along the line FF in FIG. 10, FIG. 12 is a sectional view taken along the line GG in FIG. FIG. 14 is a cross-sectional view taken along line II of FIG. However, substantially the same parts as those of the embodiment (1) are denoted by the same reference numerals, and the description is simplified.
[0040]
In the present embodiment (2), as shown in FIG. 10, the casing of the pump unit 62 includes two cylindrical casings 63 and 64 that are overlapped with the intermediate plate 65 interposed therebetween, and the openings on both the upper and lower sides thereof are connected to the casing cover 22. The inner side cover 23 is closed and each of these components is fastened and fixed in the housing 11 together with the pump cover 14 by screws 66. A pair of outer gear 67 and inner gear 69 constituting the first pump are accommodated in the space above the intermediate plate 65 in the casing of the pump portion 62, and the second pump is located in the space below the intermediate plate 65. A pair of outer gears 68 and an inner gear 70 that constitute the above are housed.
[0041]
As shown in FIGS. 13 and 14, the cylindrical casings 63 and 64 are formed with circular holes 71 and 72 at positions eccentric to the opposite sides of 180 °, and the outer gears 67 are respectively provided in the circular holes 71 and 72, respectively. 68 are rotatably fitted. Inner gears 69 and 70 are eccentrically arranged on the inner peripheral sides of the outer gears 67 and 68, respectively. In the present embodiment (2), the two inner gears 69 and 70 are arranged so as to be driven coaxially and in the same phase, and the eccentric directions of the outer gears 67 and 68 with respect to the inner gears 69 and 70 are 180 ° opposite to each other. It is shifted. Further, the number of teeth of the driving-side inner gears 69 and 70 driven to rotate by the motor unit 13 is odd, and the number of teeth of the driven-side outer gears 67 and 68 is one more than the number of teeth of the driving-side inner gears 69 and 70. It is formed in an even number.
[0042]
As shown in FIG. 10, the inner gears 69 and 70 are rotatably fitted and supported on a shaft 73 press-fitted into the central portion of the pump cover 14, and the inner gears 69 and 70 and the rotating shaft 34 of the motor unit 13 are connected to each other. , And are coupled so as to be able to transmit rotation via a coupling 74. The D-cut portion of the rotating shaft 34 of the motor unit 13 is inserted into a D-shaped connecting hole formed in the upper portion of the coupling 74, whereby the rotating shaft 34 and the coupling 74 are connected, and the lower portion of the coupling 74 is directed downward. The coupling 74 and the inner gears 69 and 70 are connected by inserting the formed connecting pins 91 into the connecting holes of the inner gears 69 and 70. When the inner gears 69 and 70 are rotationally driven by the motor unit 13, the outer gears 67 and 68 that mesh with the inner gears 69 and 70 rotate in a state where they are eccentric to each other at 180 °. 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.
[0043]
As in the embodiment (1), half of the fuel sucked from the fuel suction port 15 of the pump cover 14 is sucked into the pump chamber 76 of the lower inner gear 70 from the suction port 39 of the inner side cover 23. The remaining half of the fuel sucked from the fuel inlet 15 is the fuel introduction groove 40 (see FIGS. 10 and 11) on the inner surface of the pump cover 14 → the through passage 77 (see FIGS. 10, 13 and 14) → The air is sucked into the pump chamber 75 of the upper inner gear 69 through the path of the fuel introduction groove 43 (see FIGS. 10 and 12) on the inner surface of the casing cover 22. The through passage 77 is formed so as to penetrate the inner side cover 23, the cylindrical casing 64, the intermediate plate 65, and the cylindrical casing cover 63 in the vertical direction.
[0044]
Further, the fuel discharged from the pump chamber 76 of the lower inner gear 70 is discharged from the discharge port 45 of the inner side cover 23 → the discharge groove 47 (see FIG. 11) on the inner surface of the pump cover 14 → the discharge flow path 78 (FIG. 12 to FIG. 12). It is discharged to the motor unit 13 side through the route of FIG. The discharge passage 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 unit 13 side.
[0045]
In the present embodiment (2) described above, the number of teeth of the drive-side inner gears 69 and 70 that are rotationally driven by the motor unit 13 in the same phase is set to an odd number, and the number of teeth of the driven outer gears 67 and 68 is set to the inner gear 69, Since the number of teeth is one more than the number of teeth of 70, the rotational phases of the two outer gears 67 and 68 on the driven side are shifted by a half pitch, and the discharge pressure pulsations of the two pumps are mutually different, as in the first embodiment. The interference pressures cancel each other, the discharge pressure pulsation is greatly reduced, and the noise and vibration due to the discharge pressure pulsation are greatly reduced. This eliminates the need for conventional noise countermeasures (discharge pressure pulsation reduction device, sound insulation material, etc.), and can realize low noise and low vibration at low cost.
[0046]
Note that one inner gear may be rotated by a half pitch with respect to the other inner gear. In this case, the number of teeth of the inner gears 69 and 70 on the driving side is opposite to that in the above-described embodiment (2). It is preferable that the number of teeth of the driven outer gears 67 and 68 is an odd number that is one more than the number of teeth of the inner gears 69 and 70. Thereby, similarly to the above embodiment (2), the phases of the pulsating waves of the discharge pressures of the two pumps are shifted by a half wavelength (half cycle) of the pulsating waves, and the discharge pressure pulsation is greatly reduced.
[0047]
Further, in the above embodiment (2), the eccentric directions of the outer gears 67 and 68 of the upper and lower pumps are deviated from each other by 180 °, so that the fuel pressure rising sides are deviated from each other by 180 °. For this reason, the load in the outer diameter direction acts on the opposite sides by 180 ° between the two pumps, and the load acting in the outer diameter direction can be balanced as a whole fuel pump, and the vibration of the fuel pump can be reduced. .
[0048]
In addition, in the above embodiment (2), the intermediate plate 65 sandwiched and fixed between the two cylindrical casings 63 and 64 is interposed between the upper and lower pumps, so that the upper and lower pumps (outer gears 67 and 68) are connected to each other. The intermediate plate 65 can prevent the outer gears 67 and 68 from tilting due to the acting load (fuel pressure) in the outer diameter direction, and the rotation sliding resistance can be prevented from increasing due to the tilting of the outer gears 67 and 68. Can do.
[0049]
Further, in the above embodiment (2), even if the tooth thicknesses of the outer gears 67 and 68 and the inner gears 69 and 70 are changed, the corresponding amount is absorbed by the change in the thickness dimension of the inner side cover 23, so that the total pump length is constant. The pump discharge capacity can be changed by changing the tooth thickness without changing the overall length of the pump. For this reason, it is possible to cope with various engines having different required discharge capacities with a fuel pump of a common size, and it is possible to share fuel pump mounting parts (such as a bracket).
[0050]
In the above embodiment (2), the two inner gears 69, 70 are arranged coaxially, and the eccentric directions of the two outer gears 67, 68 with respect to the inner gears 69, 70 are shifted 180 ° opposite to each other. However, the two outer gears may be arranged on the same axis, and the eccentric directions of the two inner gears with respect to the outer gear may be shifted to the opposite sides by 180 °. 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 rotate the two outer gears together with the side cover in the same phase by the motor unit. 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 that is one less than the number of teeth of the outer gear. Further, one outer gear may be rotated with a half-pitch shift relative 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 that is one less than the number of teeth of the outer gear. What should I do?
[0051]
[Embodiment (3)]
Next, an embodiment (3) of the present invention will be described with reference to FIGS. Here, FIG. 15 is a longitudinal sectional view showing a fuel pump section 79 cut away, FIG. 16 is a JJ sectional view of FIG. 15, FIG. 17 is a KK sectional view of FIG. 15, and FIG. FIG. 19 is a sectional view of the casing cover 22 taken along line MM in FIG. However, substantially the same parts as those of the embodiment (1) are denoted by the same reference numerals, and the description is simplified.
[0052]
In the present embodiment (3), as shown in FIG. 15, the casing of the pump unit 79 is configured by closing the openings on the upper and lower sides of the cylindrical casing 21 with the casing cover 22 and the pump cover 14. A pair of outer gear 80 and inner gear 81 are housed in the casing. The outer gear 80 is rotatably fitted in the circular hole 27 of the cylindrical casing 21, and the inner gear 81 is fitted and supported on the rotating shaft 34 of the motor unit 13. The rotating shaft 34 of the motor unit 13 and the inner gear 81 are connected via a coupling 82 so as to be able to transmit rotation. When the inner gear 81 is rotationally driven by the motor unit 13, the outer gear 80 meshing with the inner gear 81 rotates.
[0053]
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 volumes are increased, and the fuel sucked from the fuel suction port 15 is supplied from the suction port 84 to the pump chamber. 83 is inhaled.
[0054]
On the other hand, as shown in FIGS. 17 to 19, two discharge ports 85 and 86 are formed in the casing cover 22 so as to communicate with the pump chamber 83 whose volume is reduced, and the fuel discharged from the pump chamber 83 is The discharge ports 85 and 86 discharge to the motor unit 13 side. By providing the discharge ports 85 and 86 as described below, the phases of the discharge pressure pulsations are configured to merge while interfering with each other with a shift of approximately a half wavelength.
[0055]
FIG. 17A shows the rotational positions of the inner gear 81 and the outer gear 80 when the volume of the pump chamber 83a in the boundary region between the suction region and the discharge region becomes maximum, and FIG. The state when the inner gear 81 and the outer gear 80 are rotated by a half pitch from the position a) is shown. As shown in FIG. 17A, the first discharge port 85 (upstream discharge port) has a length corresponding to approximately a half pitch from the partition position between the pump chamber 83a having the maximum volume and the adjacent pump chamber 83b. 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 having the maximum volume, and as shown in FIG. The end position of the eye discharge port 85 is in the vicinity of the end of the pump chamber 83a formed when the two gears 80, 81 have moved half-phase.
[0056]
Further, the second discharge port 86 (downstream discharge port) is formed at a position away from the first discharge port 85 by approximately 1.5 pitches 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 with the maximum volume, the second discharge port 86 starts to open to the pump chamber 83b adjacent to the pump chamber 83a with the maximum volume after a half pitch delay. It is like that.
[0057]
Accordingly, a part of the fuel in the pump chamber 83a having the maximum volume shown in FIG. 17A starts to be discharged from the first discharge port 85, and then is delayed from the second discharge port 86 by a half pitch. The remaining fuel in the pump chamber 83b adjacent to the maximum volume pump chamber 83a is discharged. As a result, the vertical movement 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 approximately a half wavelength.
[0058]
The interval between the two discharge ports 85 and 86 may be determined in accordance with the number of teeth of the inner gear 81 and the outer gear 80. Even if the number of teeth changes, one pump chamber (between teeth) The second discharge port may be formed at a position where the chamber) can be formed.
[0059]
Further, as shown in FIG. 19, 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 discharge ports 85 and 86. ing. Furthermore, a taper portion 88 that extends toward the pump chamber 83 is formed at the inlet of the discharge port 86.
[0060]
In the present embodiment (3) described above, the discharge ports 85 and 86 from which the fuel in the pump chamber 83 is discharged are formed so as to merge while interfering with the phase of the discharge pressure pulsation being shifted by approximately a half wavelength. The discharge pressure pulsations of the two discharge ports 85 and 86 interfere with each other and cancel each other out, the discharge pressure pulsations are greatly reduced, and noise and vibration due to the discharge pressure pulsations are greatly reduced. Thereby, compared with the case where the two pumps are provided to reduce the discharge pressure pulsation as in the embodiments (1) and (2), the number of parts can be reduced and the configuration can be simplified. It is possible to achieve weight reduction and cost reduction while realizing noise reduction and vibration reduction.
[0061]
[Embodiment (4)]
Next, Embodiment (4) of this invention is demonstrated using FIG. 20 thru | or FIG. Here, FIG. 20 is a longitudinal sectional view showing the fuel pump section 90 cut away, FIG. 21 is an NN sectional view of FIG. 20, FIG. 22 is a PP sectional view of FIG. 20, and FIG. 24 is a cross-sectional view taken along the line Q-Q, FIG. 24 is a cross-sectional view taken along the line RR in FIG. 20, and FIG. 25 is a view for explaining the positions where the discharge ports 98 and 99 and the communication groove 100 are formed. In addition, about the substantially same part as the said embodiment (1), the same code | symbol is attached | subjected and description is simplified.
[0062]
In the present embodiment (4), as shown in FIG. 20, the casing of the pump unit 90 is configured by closing the openings on the upper and lower sides of the cylindrical casing 21 with the casing cover 22 and the inner side cover 23. A pair of outer gear 92 and inner gear 93 are accommodated in the 90 casing. The inner gear 93 is rotatably fitted and supported on a radial bearing 36 press-fitted into the casing cover 22, and the rotating shaft 34 of the motor unit 13 is inserted inside the radial bearing 36. In this embodiment (4), as shown in FIG. 21, the number of teeth of the outer gear 92 is 6, and the number of teeth of the inner gear 93 is 5.
[0063]
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 a coupling-shaped connecting hole 95 formed at the center of the inner gear 93. The rotating shaft 34 of the motor unit 13 and the inner gear 93 are connected via a coupling 94 so as to be able to transmit rotation.
[0064]
Further, as shown in FIG. 22, a suction port 97 is formed in the inner side cover 23, and the fuel sucked from the fuel suction port 15 is sucked into the pump chamber 96 from the suction port 97.
[0065]
On the other hand, as shown in FIGS. 23 to 25, two discharge ports 98 and 99 are formed in the casing cover 22 so as to communicate with the pump chamber 96 whose volume decreases, and the fuel discharged from the pump chamber 96 is , And discharged from the discharge ports 98 and 99 to the motor unit 13 side.
[0066]
FIG. 25A shows the rotational positions of the inner gear 93 and the outer gear 92 when the volume of the pump chamber 96a in the boundary region between the suction region and the discharge region is maximized, and FIG. The state when the inner gear 93 and the outer gear 92 are rotated by a half pitch from the position a) is shown. Also in the present embodiment (4), as in the embodiment (3), as shown in FIG. 25 (a), the upstream discharge port 98 includes the pump chamber 96a having the maximum volume and the pump chamber 96b adjacent thereto. The downstream discharge port 99 is formed at a position away from the upstream discharge port 98 in the rotational direction by approximately 1.5 pitches. Thereby, a part of the fuel in the pump chamber 96a having the maximum volume shown in FIG. 25A starts to be discharged from the upstream discharge port 98, and is delayed from the downstream discharge port 99 by about a half pitch. The remaining fuel in the pump chamber 96b adjacent to the pump chamber 96a is discharged, and the phases of the discharge pressure pulsations of the two discharge ports 98 and 99 are shifted by approximately a half wavelength and merged while interfering with each other.
[0067]
In the present embodiment (4), the discharge ports 98 and 99 are entirely formed in a substantially rectangular shape without narrowing the upstream and downstream ends of the discharge ports 98 and 99, and the pump chambers of the discharge ports 98 and 99 are formed. The opening area with respect to 96 is made large.
[0068]
The casing cover 22 is formed with a communication groove portion 100 having a predetermined step (for example, 0.1 mm) with respect to the lower surface of the casing cover 22 so as to extend from the downstream end portion of the upstream discharge port 98 in the rotational direction. ing. As a result, as shown in FIG. 25B, the pump chamber 96 b that has passed through the upstream discharge port 98 is communicated with the upstream discharge port 98 by the communication groove portion 100. When the pump chamber 96b moves half a pitch from the position shown in FIG. 25 (a) to the position shown in FIG. 25 (b), the pump chamber 96b starts to communicate with the downstream discharge port 99. Further, when the half pitch is moved from the position shown in FIG. 25 (b), it moves to the position of the pump chamber 96c shown in FIG. 25 (a).
[0069]
In this case, the length of the communication groove portion 100 in the rotation direction is set so that the front end portion of the communication groove portion 100 communicates with the pump chamber 96 c that discharges fuel to the downstream discharge port 99. Accordingly, at the rotational position shown in FIG. 25A, the upstream discharge port 98 and the downstream discharge port 99 are communicated with each other via the communication groove portion 100 and the pump chamber 96c.
[0070]
In the pump section 90 configured as described above, the fuel shown in FIG. 25B is delayed by a half pitch 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 chamber 96b is discharged from the downstream discharge port 99, and the phases of the discharge pressure pulsations of the two discharge ports 98 and 99 are shifted by approximately a half wavelength and merge while interfering with each other.
[0071]
At this time, as shown in FIG. 25B, a part of the fuel pressurized in the pump chamber 96 b that has passed through the upstream discharge port 98 flows backward into the communication groove 100 and flows into the upstream discharge port 98. . Thereby, in the upstream discharge port 98, two pressure pulsations out of phase discharged from the two adjacent pump chambers 98a and 98b interfere with each other, and the discharge pressure of the upstream discharge port 98 is caused by the interference effect. Pulsation is reduced.
[0072]
Furthermore, as shown in FIG. 25A, the communication groove portion 100 is formed so as to communicate with the pump chamber 96c that discharges fuel to the downstream discharge port 99, so that the upstream discharge port 98 and the downstream discharge port 99 communicates with the communication groove portion 100 via the pump chamber 96c. Thus, in the downstream discharge port 99, the discharge pressure pulsation of the pump chamber 96c that discharges fuel to the downstream discharge port 99 and the pressure pulsation that propagates from the upstream discharge port 98 through the communication groove 100 and the pump chamber 96c. And become to interfere. As described above, since the pressure pulsation propagating from the upstream discharge port 98 is approximately half a wavelength ahead of the discharge pressure pulsation of the downstream discharge port 99, the interference of these two pressure pulsations causes the downstream discharge port 99 to move. The discharge pressure pulsation is effectively reduced.
[0073]
Therefore, in the present embodiment (4), in the state where both the discharge pressure pulsation of the upstream discharge port 98 and the discharge pressure pulsation of the downstream discharge port 99 are reduced by the communication groove portion 100, The discharge pressure pulsation joins while interfering with a shift of almost half wavelength in the flow path outside the pump unit 90, and the effect of reducing the discharge pressure pulsation of the entire pump can be further improved. Vibration can be effectively reduced.
[0074]
In this embodiment (4), the length of the communication groove portion 100 in the rotational direction is set so that the communication groove portion 100 communicates with the pump chamber 96c that discharges fuel to the downstream discharge port 99. The length of 100 may be shortened so that it does not reach the pump chamber 96c. Even in this case, the effect of reducing the discharge pressure pulsation of the upstream discharge port 98 by the communication groove portion 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.
2 is a cross-sectional view taken along the line DD of FIG. 3;
FIG. 3 is a bottom view of the fuel pump.
4 is a cross-sectional view taken along the line BB in FIG.
5 is a cross-sectional view taken along the line CC in FIG.
6 is a cross-sectional view taken along line AA in FIG.
FIG. 7 is a view for explaining the structure of a conventional trochoid gear type fuel pump.
FIG. 8 is a longitudinal sectional view showing the fuel pump in a modified example of the embodiment (1) of the present invention, with the pump section broken away.
9 is a cross-sectional view taken along line EE in FIG.
FIG. 10 is a longitudinal sectional view showing the fuel pump according to the embodiment (2) of the present invention in a cutaway manner.
11 is a sectional view taken along line FF in FIG.
12 is a cross-sectional view taken along line GG in FIG.
13 is a cross-sectional view taken along line HH in FIG.
14 is a cross-sectional view taken along the line II of FIG.
FIG. 15 is a longitudinal sectional view showing a fuel pump according to an embodiment (3) of the present invention in a cutaway manner.
16 is a sectional view taken along line JJ in FIG.
FIGS. 17A and 17B are views for explaining the formation position of the discharge port, and FIGS. 15A and 15B are cross-sectional views taken along the line KK in FIG.
18 is a cross-sectional view taken along line LL in FIG.
19 is a sectional view of the casing cover taken along line MM in FIG.
FIG. 20 is a longitudinal sectional view showing the fuel pump according to the embodiment (4) of the present invention in a cutaway manner.
21 is a sectional view taken along line NN in FIG.
22 is a cross-sectional view taken along the line PP in FIG.
23 is a cross-sectional view taken along QQ in FIG.
24 is a cross-sectional view taken along line RR in FIG.
FIGS. 25A and 25B are diagrams for explaining the formation positions of the discharge port and the communication groove, and FIGS. 25A and 25B are views showing the state of the gear rotation position shifted by a half pitch. FIGS.
[Explanation of symbols]
DESCRIPTION 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 ... Inner side cover, 24 ... Outer gear 24a ... inner teeth, 25,26 ... inner gears, 25a, 26a ... outer teeth, 28 ... partition walls, 29,30 ... pump chamber, 31,32 ... cylindrical bearings, 34 ... rotary shaft, 39 ... suction port, 40 ... Fuel introduction groove, 42 ... Through passage, 43 ... Fuel introduction groove, 44, 45 ... Discharge port, 47 ... Discharge groove, 48 ... Discharge passage, 62 ... Pump section, 63, 64 ... Cylindrical casing, 65 ... Intermediate plate , 67, 68 ... outer gear, 69, 70 ... inner gear, 73 ... shaft, 75, 76 ... pump chamber, 77 ... through passage, 78 ... discharge passage, 79 ... pump section, 80 ... outer gear, DESCRIPTION OF SYMBOLS 1 ... Inner gear, 83 ... Pump chamber, 84 ... Suction port, 85, 86 ... Discharge port, 90 ... Pump part, 92 ... Outer gear, 93 ... Inner gear, 97 ... Suction port, 98, 99 ... Discharge port, 100 ... Communication groove part .

Claims (3)

An inner gear with external teeth is arranged eccentrically on the inner peripheral side of the outer gear with internal teeth, and the pump chamber formed between the teeth of both gears by meshing both gears is moved in the rotational direction by the rotation of both gears. , together with the volume of the pump chamber continuously increases or decreases configured to suction and discharge the fuel, the discharge port the fuel of the pump chamber is discharged is formed in two places, the discharge of these two places In the fuel pump configured to merge while interfering with the phase of the discharge pressure pulsation of the port shifted by almost a half wavelength ,
The start position of the upstream discharge port of the two discharge ports is set in the vicinity of the end of the pump chamber where the volume is maximum, and the end position of the upstream discharge port is determined when both gears move half-phase. Set near the end of the pump chamber to be formed,
A fuel pump , wherein a start position of a downstream discharge port is set in the vicinity of a first pump chamber end formed from an upstream discharge port end portion . A communication groove that extends 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 communicates with the upstream discharge port by the communication groove. The fuel pump according to claim 1 , wherein the fuel pump is configured. 3. The fuel pump according to claim 2 , wherein a length of the communication groove portion in the rotation direction is set so that the communication groove portion communicates with a pump chamber that discharges fuel to a downstream discharge port.

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