JP2001280261A - Fuel pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce noise and vibration due to rattling and whirling of an outer gear of a trochoid gear type fuel pump. SOLUTION: When an inner gear 26 is rotated by a motor, the outer gear 25 is rotated to repeat continuous increasing the decreasing of capacity of each pump chamber 30 between the both gears 25 and 26. Fuel is transferred to the inside of the pump chamber 30 with increased capacity, and fuel is discharged from a discharge port 38 while it is pressurized in the pump chamber 30 with decreased capacity. Elastic pressing members 42 are stored in respective two storage recessed parts 41 formed on an inner peripheral part of a pump casing 21. Noise and vibration due to rattling and whirling of the outer gear 25 are reduced by pressing the outer gear 25 onto an inner peripheral surface of the discharge port 38 side of the pump casing 21 by elastic force of the both elastic pressing members 42 and high fuel pressure on the discharge port 38 side.

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. 4, 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]

However, it is necessary to provide a clearance (gap) between the outer periphery of the outer gear 2 and the inner periphery of the pump casing 1 in consideration of manufacturing tolerance, sliding resistance and the like. There is a disadvantage that rattling or whirling of the outer gear 2 occurs in the inside, whereby the outer gear 2 collides with the inner peripheral surface of the pump casing 1 and noise and vibration increase.

[0004] Incidentally, in Japanese Patent Application Laid-Open No. 5-133347,
The clearance between the outer gear outer periphery and the pump casing inner periphery is increased, and the outer gear outer periphery is
The outer gear is elastically supported by the elastic support mechanism at intervals of °, and when foreign matter enters the clearance between the outer gear outer circumference and the pump casing inner circumference, the outer gear moves in the direction opposite to the foreign matter entry position, so that the outer gear is caught by the foreign matter. I try to prevent the lock. However, as disclosed in this publication, the clearance between the outer gear and the pump casing is increased, and the outer gear is floated with respect to the pump casing by an elastic support mechanism so as to be elastically supported.
As a result, it becomes more difficult to reduce the whirling of the outer gear than before, and the whirling of the outer gear is amplified, and the noise and vibration are adversely affected and the noise and vibration are increased. Becomes

[0005] The present invention has been made in view of such circumstances, and an object thereof is to provide a trochoid gear type fuel pump that can reduce noise and vibration due to rattling and whirling of the outer gear. It is in.

[0006]

According to a first aspect of the present invention, there is provided a trochoid gear type fuel pump according to the present invention, wherein an outer gear is pressed against a cylindrical pump casing by an elastic force in one direction. This is a configuration provided with a pressing means. As described above, when the outer gear is pressed against the pump casing in one direction, the outer gear rotates while being pressed at a fixed position on the inner peripheral surface of the pump casing, so that rattling and whirling of the outer gear are suppressed, Noise and vibration due to rattling and whirling of the outer gear are effectively reduced.

In a trochoid gear type fuel pump, the volume of the pump chamber decreases after the fuel is sucked into the pump chamber in a region where the volume of the pump chamber increases between the teeth of the two gears due to the rotation of the two gears. The fuel in the pump chamber is discharged while being pressurized in the region. At this time, in the area on the discharge side where the volume of the pump chamber decreases, the fuel in the pump chamber is pressurized and the fuel pressure (fuel pressure) increases, so that the outer pressure is applied to the outer gear due to the increase in the fuel pressure.
Since the load in the radial direction due to such a rise in fuel pressure does not occur in the suction-side region where the fuel pressure in the pump chamber decreases,
The outer radial load due to the fuel pressure on the outer gear acts only on the discharge side region where the fuel pressure in the pump chamber increases.

In consideration of these characteristics, the direction in which the outer gear is pressed by the elastic pressing means is such that the volume of the pump chamber between the teeth of the two gears decreases and the fuel pressure in the pump chamber increases. It is preferable to set the direction to the discharge side. With this configuration, since the elastic force of the elastic pressing means acting on the outer gear and the direction of action of the fuel pressure are substantially the same, the outer gear is pressed against the pump casing by effectively utilizing the fuel pressure in addition to the elastic force of the elastic pressing means. Therefore, rattling and whirling of the outer gear can be suppressed more reliably. Further, the elastic force of the elastic pressing means necessary for suppressing the rattling and whirling of the outer gear can be reduced by the fuel pressure, and the cost of the elastic pressing means can be reduced accordingly.

According to the present invention, the elastic force of the elastic pressing means may be intensively applied to one location on the outer periphery of the outer gear. In this case, however, the direction of action of the elastic force is accurately adjusted to the center of the outer gear. It is necessary to be configured so as to pass through, and is easily affected by manufacturing variations and the like.

Therefore, the outer periphery of the outer gear is pressed at a plurality of points by the elastic pressing means, and the direction of the resultant force of the pressing force is set so as to be directed to the discharge side where the fuel pressure of the pump chamber becomes high. Good. If you do this,
The direction in which the outer gear is pressed by the elastic pressing means can be stabilized, and the outer gear can be stably pressed in the direction of the discharge side without being affected by manufacturing variations or the like.

Further, during rotation of both gears, in addition to the fuel pressure of the pump chamber, a force for pressing the outer gear is generated by a rotational driving force acting on the outer gear from the inner gear. The direction in which the outer gear is pressed may be set to the direction of the resultant force of the pressing force of the outer gear generated by the fuel pressure of the pump chamber and the pressing force of the outer gear generated by the rotational driving force of the inner gear. With this configuration, in addition to the fuel pressure, the outer gear can be pressed against the pump casing by effectively utilizing the pressing force of the outer gear due to the rotational driving force of the inner gear, and the elastic force of the elastic pressing means can be reduced accordingly.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIG.
This will be described with reference to FIG. First, the configuration of the entire trochoid gear type fuel pump will be schematically described with reference to FIG. A motor section 12 and a trochoid gear type pump 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 13 is fixed by caulking or the like, and a fuel inlet (not shown) formed in the pump cover 14 is provided in a fuel tank (not shown). Fuel is sucked into the pump unit 13. A motor cover 16 that covers the motor unit 12 is fixed to the other end (upper end) of the housing 11 by caulking or the like.
Is provided with a connector 17 for supplying electricity to the motor section 12 and a fuel discharge port 18. The fuel discharged from the pump unit 13 is discharged from the fuel discharge port 18 through a gap between the armature 19 of the motor unit 12 and the magnet 20.

Next, the configuration of the trochoid gear type pump unit 13 will be described with reference to FIGS. Pump section 13
Is formed by closing the upper and lower openings of a cylindrical pump casing 21 with a casing cover 22 and an inner side cover 23, and these three parts are fixedly fastened with screws 24. And is fixed by caulking or the like. An outer gear 25 and an inner gear 26 are housed in the pump casing 21.

As shown in FIG. 2, on the inner peripheral side of the outer gear 25 and on the outer peripheral side of the inner gear 26, there are formed internal teeth 27 and external teeth 28, respectively. One less than the number of the internal teeth 27 is formed. The tooth thickness of the inner gear 26 is formed to be the same as the tooth thickness of the outer gear 25. Outer gear 25
Is rotatably fitted in a circular hole 29 formed eccentrically in the pump casing 21, and the fitting portion (sliding portion) has a necessary minimum in consideration of manufacturing tolerance and sliding resistance. Clearance is formed. The thickness dimension (axial dimension) of the outer gear 25 is smaller than the thickness dimension of the pump casing 21 by the side clearance.

An inner gear 26 is eccentrically housed on the inner peripheral side of the outer gear 25.
A plurality of pump chambers 30 are formed between the teeth 27 and 28 by meshing or contacting the teeth 7 and 28. In this case, since the outer gear 25 and the inner gear 26 are eccentric to each other, the amount of engagement between the teeth 27 and 28 of the two gears 25 and 26 continuously increases and decreases during rotation, and the volume of each pump chamber 30 is continuously increased. The operation of increasing / decreasing is repeated with one rotation as a cycle.

As shown in FIG. 1, the casing cover 22
A cylindrical bearing 32 is inserted into an insertion hole 31 formed in the center of the
The rotary shaft 33 of the motor unit 12 is rotatably inserted into and supported by the inner diameter of the bearing 32. This bearing 3
Reference numeral 2 protrudes to about 1/2 of the thickness of the inner gear 26, and a shaft hole 34 formed at the center of the inner gear 26 is rotatably fitted to the bearing 32. The rotating shaft 33 of the motor portion 12 projects downward from the bearing 32, and a D-cut portion 35 formed at the projecting portion is fitted into a D-shaped connection hole 36 formed below the shaft hole 34 of the inner gear 26. I have. Thus, when the rotation shaft 33 of the motor section 12 rotates, the inner gear 26 rotates integrally therewith, and further, the outer gear 25 meshing with the inner gear 26 also rotates. Note that a coupling may be used as a connecting means between the rotation shaft 33 of the motor unit 12 and the inner gear 26.

The inner side cover 23 has a fuel inlet 1
A suction port 37 for sucking fuel from 5 into the pump chamber 30 is formed. As shown in FIG. 2, the suction port 37 extends in a groove shape in the circumferential direction along the inner side surface of the inner side cover 23, and has a plurality of pump chambers 30 whose volume is increased by rotation of the gears 25 and 26. It is formed in a bow shape so as to communicate with.

Further, a discharge port 38 (see FIG. 2) is formed in the inner side cover 23 at a position substantially 180 ° opposite to the suction port 37. This discharge port 3
8 is formed in a bow shape so as to extend in a groove shape in the circumferential direction along the inner side surface of the inner side cover 23 and communicate with a plurality of pump chambers 30 whose volume is reduced by the rotation of the gears 25 and 26. Have been. The fuel discharged from the discharge port 38 is supplied to a discharge groove (not shown) on the inner surface of the pump cover 14 → a through hole (not shown) of the internal side cover 23 → a through flow channel 39 of the pump casing 21 (see FIG. 2). → Discharged to the motor section 12 through a passage of a through flow path (not shown) of the casing cover 22. Note that a discharge port may be formed in the casing cover 22 and fuel may be discharged directly from the discharge port to the motor unit 12 side.

As described above, when the inner gear 26 is driven to rotate by the motor section 12, the inner gear 26
The outer gear 25 meshing with the gears rotates, and both gears 25, 2
The operation of continuously increasing / decreasing the meshing amount of the teeth 27, 28 of the sixth, and continuously increasing / decreasing the volume of each pump chamber 30 formed between the teeth 27, 28 is repeated with one rotation as a cycle. . Thus, in the pump chamber 30 having a larger volume, the fuel is transferred in the rotation direction of the two gears 25 and 26 while sucking the fuel from the suction port 37. In the pump chamber 30 having a smaller volume, the transferred fuel is pressurized while being compressed. Discharge is performed from the discharge port 38.

Next, a configuration in which the outer gear 25 is pressed against the pump casing 21 in one direction by an elastic force will be described. On the suction port 37 side of the inner peripheral portion of the pump casing 21, two storage recesses 41 are formed at an interval of substantially 90 °, and an elastic pressing member 42 (elastic pressing means) is stored in each storage recess 41. I have. Each elastic pressing member 42
It is made of an elastic material (for example, nylon or the like) having a small sliding resistance to the outer gear 25 and having excellent wear resistance and gasoline resistance, and an elastic piece 42a is integrally formed. The elastic piece 42a of each elastic pressing member 42 is
The elastic pressing member 42 is pressed against the outer peripheral surface of the outer gear 25 by the elastic deformation of the elastic piece 42a, and the outer gear 25 is pressed against the pump casing 21 in one direction.

In this case, in the area on the discharge port 38 side where the volume of the pump chamber 30 is reduced, the fuel in the pump chamber 30 is pressurized and the fuel pressure rises. Load is applied. Since the load in the radial direction due to such a rise in fuel pressure does not occur in the region on the suction port 37 side where the fuel pressure in the pump chamber 30 decreases, the load in the radial direction due to the fuel pressure on the outer gear 25 is the fuel pressure in the pump chamber 30. Works only in the region on the discharge port 38 side where the pressure rises.

In consideration of this point, the direction in which the outer gear 25 is pressed by each elastic pressing member 42 passes through the center of rotation of the outer gear 25, and the resultant force of the pressing force is directed to the direction of the arc-shaped discharge port 38. . As a result, the elastic force of the elastic pressing member 42 acting on the outer gear 25 and the action direction of the fuel pressure become substantially the same, and the outer gear 25 is moved by the elastic force of the elastic pressing member 42 and the fuel pressure.
1 is held.

During the rotation of the two gears 25 and 26, in addition to the fuel pressure in the pump chamber 30, the inner gear 26
The force that presses the outer gear 25 is also generated by the rotational driving force acting on the outer gear 25. Therefore, the direction in which the outer gear 25 is pressed by the elastic pressing member 42 is the pressing force of the outer gear 25 generated by the fuel pressure of the pump chamber 30 and the outer gear 2 generated by the rotational driving force of the inner gear 26.
The direction of the resultant force with the pressing force of No. 5 may be set. The direction of the resultant force falls within the range of the discharge port 38.

According to the present embodiment described above, the outer gear 25 is pressed against the discharge port 38 by the two elastic pressing members 42, so that the elastic force and the fuel pressure of the elastic pressing member 42 acting on the outer gear 25 are reduced. The action directions are substantially the same, and the outer gear 25 can be reliably pressed against the inner peripheral surface of the pump casing 21 on the discharge port 38 side by the elastic force of the elastic pressing member 42 and the fuel pressure. Thereby, rattling and whirling of the outer gear 25 can be suppressed, and noise and vibration due to rattling and whirling of the outer gear 25 can be effectively reduced.

Further, since the fuel pressure can be effectively used as a load for pressing the outer gear 25 against the pump casing 21, the elastic force of the elastic pressing member 42 required to suppress the rattling and whirling of the outer gear 25 is reduced by the fuel pressure. The size of the elastic pressing member 42 can be reduced because of the small size.

However, in the present invention, the outer gear 25 may be pressed in a direction other than the discharge port 38 by the elastic pressing member 42 (elastic pressing means). Even in this case, the elastic force of the elastic pressing member 42 is increased to some extent. By doing so, rattling and whirling of the outer gear 25 can be suppressed.

In the present embodiment, the outer gear 25 is pressed in one direction by the two elastic pressing members 42, so that the pressing direction of the outer gear 25 by the elastic pressing members 42 can be stabilized, and manufacturing variations and the like can be achieved. , The outer gear 25 can be stably pressed in the direction toward the discharge port 38 side. Note that the same effect can be obtained even if three or more elastic pressing members 42 are provided, and the arrangement intervals of the elastic pressing members 42 may be appropriately changed. However, in the present invention, only one elastic pressing member 42 may be provided, and even in this case, the intended object of the present invention can be achieved.

In the present embodiment, the elastic pressing member 42
Although the elastic piece portion 42a is formed integrally with the outer gear 25, the elastic pressing member may be pressed against the outer gear 25 by a spring material such as a separate pulling housed in the housing recess 41 and the elastic force of the spring material. .

In addition, the present invention can be implemented with various changes without departing from the gist, such as by appropriately changing the number of teeth of the outer gear 25 and the inner gear 26.

[Brief description of the drawings]

FIG. 1 is a front view showing a main part of a fuel pump according to an embodiment of the present invention in a cutaway manner.

FIG. 2 is a cross-sectional view of the pump section taken along line AA of FIG. 1;

FIG. 3 is an enlarged cross-sectional view showing an arrangement state of an elastic pressing member.

FIG. 4 is a cross-sectional view of a pump section of a conventional trochoid gear type fuel pump.

[Explanation of symbols]

11 housing, 12 motor part, 13 pump part,
14 pump cover, 15 fuel inlet, 18 fuel outlet, 21 pump casing, 22 casing cover, 23 internal side cover, 25 outer gear, 26
... inner gear, 27 ... internal teeth, 28 ... external teeth, 30 ... pump chamber, 32 ... bearing, 33 ... rotating shaft, 37 ... suction port, 3
8: discharge port, 41: storage recess, 42: elastic pressing member (elastic pressing means), 42a: elastic piece.

Claims (4)

[Claims] An inner gear with external teeth is eccentrically arranged on the inner peripheral side of an outer gear with internal teeth rotatably housed in a cylindrical pump casing. In a fuel pump for sucking / discharging fuel by continuously increasing / decreasing the volume of the pump chamber while moving the formed pump chamber in the rotation direction by the rotation of both gears, the outer gear relative to the pump casing A fuel pump provided with elastic pressing means for pressing the elastic member in one direction by an elastic force. 2. The direction in which the elastic gear presses the outer gear is set in the direction of the discharge side where the volume of the pump chamber between the teeth of the two gears decreases and the fuel pressure in the pump chamber increases. The fuel pump according to claim 1, wherein: 3. The elastic pressing means presses the outer periphery of the outer gear at a plurality of places, and the direction of the resultant force of the pressing is directed to the direction of the discharge side where the fuel pressure of the pump chamber becomes high. The fuel pump according to claim 2, wherein 4. The direction in which the elastic gear presses the outer gear is the direction of the resultant force of the pressing force of the outer gear generated by the fuel pressure of the pump chamber and the pressing force of the outer gear generated by the rotational driving force of the inner gear. The fuel pump according to claim 2, wherein the fuel pump is set to: