JP3102522B2 - Gear pump - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

In the present invention, a plurality of pressure chambers are formed between an eccentric inner rotor and an outer rotor, and the inner rotor and the outer rotor are rotated to discharge the fluid in the pressure chambers. Regarding the gear pump,
For example, the present invention is applied to a vehicle fuel pump.

[0002]

2. Description of the Related Art Gear pumps of the trochoid type or the like have been widely known. Japanese Patent Application Laid-Open No. 61-160590 proposes such a positive displacement rotary pump used as a fuel pump for a vehicle. Such a gear pump forms a plurality of pressure chambers between an outer rotor having internal teeth formed therein, and an inner rotor having eccentrically housed inside the outer rotor and having external teeth meshing with the internal teeth. I have. The fluid is sucked and discharged by rotating the outer rotor and the inner rotor and moving the pressure chamber while changing the volume.

[0003]

In recent years, as the quietness of vehicles has improved, there has been a demand for a reduction in discharge pulsation of a fuel pump, especially a trochoid pump or the like. However, in the structure for driving the trochoid rotor disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 61-160590, there is a problem that the tip clearance increases and decreases with the rotation cycle of the rotor because the inner rotor whirls. Also,
In the structure disclosed in U.S. Pat. No. 4,820,138, although the above problem can be solved, there is a problem that the coupling is pressed against the cover by the pressure inside the pump and is worn.

An object of the present invention is to provide a gear pump that prevents a coupling connecting a drive shaft and an inner rotor from being pressed in one direction by a pressure difference of a fluid, reduces wear of each member, and improves pump efficiency. Aim.

[0005]

A gear pump according to the present invention for solving the above-mentioned object has an outer rotor formed with internal teeth, and external teeth housed in the outer rotor and meshing with the internal teeth. An inner rotor, a casing forming the side walls of a plurality of pressure chambers formed between the inner teeth and the outer teeth, rotatably accommodating the outer rotor and the inner rotor and eccentrically housing the outer rotor and the inner rotor; A drive shaft for rotating the inner rotor and moving the pressure chamber while changing its volume, a suction port provided in communication with the increasing pressure chamber, and a decreasing pressure chamber. a discharge port provided in communication, and coupling with a second engagement portion engaged with the inner groove portion of the first fitting portion and the inner rotor fitted to an end portion of the drive shaft Provided the low pressure side of the coupling
From the low pressure side to the high pressure side
And a pressure balance chamber to be applied, wherein the coupling is
It is characterized by having a pressure balance passage communicating the high pressure side around the coupling with the pressure balance chamber . According to the gear pump according to claim 2 of the present invention, the pressure
The high pressure side end face of the coupling and the low pressure
It is a communication hole opened on the side end surface.

[0006]

According to the gear pump of the present invention, when fluid is pumped from the suction port to the discharge port via the pressure chamber,
A pressure difference occurs between the discharge port and the suction port. At this time, the fluid tries to leak from the high pressure discharge port side to the low pressure suction port side via the sliding portion around the drive shaft,
The coupling tends to be pressed against the casing by the pressure of the fluid. However, since the pressure difference between the high pressure side and the low pressure side around the coupling is eliminated by the pressure balance passage, the contact force between the coupling and the casing is reduced, so that wear is reduced.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a vehicle fuel pump will be described below with reference to FIGS. The fuel pump for a vehicle according to this embodiment is provided with a fuel filter (not shown) or the like, and is housed in a fuel tank for use. FIG. 1 is a partial sectional view of a vehicle fuel pump, and FIG.
FIG. 3 is a partial cutaway overall view, and FIG. 3 is a sectional view taken along the line AA shown in FIG.

In FIG. 1 to FIG. 3, a cover 11 is provided at one end of a cylindrical housing 10 of the fuel pump 1. The cover 11 includes a power supply connector 13.
And a discharge port 14 from which pressurized fuel is discharged. A motor part as a driving means is built in a central part 12 of the housing 10. A pump unit 30 is provided at the other end of the housing 10. Pump unit 30
Are a pump casing 31, a spacer 32, an outer rotor 33, an inner rotor 34, and a pump cover 36.
And

The pump casing 31 is connected to the housing 10
Is pressed into the inner circumference of In the pump casing 31,
A hole is formed in the center thereof, and a bearing 37 of the shaft 21 of the armature 20 of the motor unit and a cylindrical bush 38 are press-fitted. Further, the pump casing 31 includes
A discharge port 39 is formed over a predetermined range, and the discharge port 39 communicates with the inside of the housing 10 via a discharge passage 40. The discharge port 39 is shown in FIG. 3 as a virtual line (two-dot chain line).

The disk-shaped spacer 32 is connected to the housing 10.
It is inserted in the inner circumference of and is prevented from rotating. Spacer 32
Is formed with a cylindrical hole whose center is displaced by a predetermined amount. The disk-shaped outer rotor 33 is provided with a spacer 32.
And a trochoid tooth is formed inside the cylindrical hole.

The inner rotor 34 is housed inside the outer rotor 33. On the outer side of the inner rotor 34, trochoid teeth having one less tooth than the trochoid teeth of the outer rotor 33 are formed, and a hole is formed on the inner side.
A bearing 34a is press-fitted into a hole inside the inner rotor 34, and the inner rotor 34 is rotatably supported by the bush 38 via the bearing 34a.

The pump casing 31 has four female screw holes (not shown), and the spacer 32 has holes through which screws 43 pass. The pump casing 31 and the spacer 32 are tightened by a screw 43. In addition, the outer rotor 33 and the inner rotor 34 are formed to be about 10 to 30 μm thinner than the spacer 32 so as to be rotatably accommodated.

Further, the pump cover 36 is inserted into the inner periphery of the housing 10 so as to restrict the axial movement of the outer rotor 33 and the inner rotor, and is fixed by caulking. The pump cover 36 has a suction port 42 and a suction port 41 communicating therewith. Suction port 4 formed over a predetermined range in pump cover 36
1 is shown in FIG. 3 as a hidden line (dashed line).

The shaft 21 is rotatably supported by a bearing 37 and is axially supported by a pin 22. As shown in FIG. 4, the coupling 23 connecting the shaft 21 and the inner rotor 34 has a stepped cylindrical shape, and has two parallel surfaces 23a and 23b penetrating in the axial direction at the center of the coupling 23. An inner hole is formed. The two parallel surfaces 23a and 23b are fitted into two parallel cutout surfaces 21a and 21b formed on the outer periphery of the end of the shaft 21. Protrusions 23d and 23e are formed on the radial direction side of the annular small cylindrical portion 23c of the coupling 23 so as to engage with the inner wall groove 34a of the inner rotor 34, and the protrusions 23d and 23e are formed.
Is located in the middle of the adjacent two parallel surfaces 23a and 23b.

Further, a projection 23d of the coupling 23,
Pressure balancing holes 23g and 23h penetrating in the axial direction are formed in 23e and the large cylindrical portion 23f. A pressure balance chamber is formed by the pressure balance holes 23g and 23h.
The chamber 36a on the side of the pin 22 and the chamber 38a on the side of the bush 38
By maintaining the oil pressure balance equally, wear of the contact portion between the coupling 23 and the pump cover 36 is reduced. The coupling 23 transmits the rotational force of the shaft 21 to the inner rotor 34.

The outer rotor 33 and the inner rotor 34 are mounted eccentrically by a predetermined amount as shown in FIG.
A plurality of pressure chambers 50 are formed between trochoid teeth formed on the inner periphery of the outer rotor 33 and trochoid teeth formed on the outer periphery of the inner rotor 34. The pressure chamber 50 is formed by the pump casing 31 and the pump cover 36.
Are formed.

Next, the operation of this embodiment will be described. In actual use, a fuel filter (not shown) is attached to the suction port 42 of the fuel pump 1 shown in FIG.
4 is connected to a pipe directed to a fuel injection device of a vehicle engine (not shown), and a connector 13 is connected to a connector connected to a vehicle-mounted battery (not shown). Is held.

When a current is supplied from the connector 13, the shaft 21 is rotated by the motor. The shaft 21
It rotates clockwise in FIG. The rotation of the shaft 21 rotates the inner rotor 34 via the coupling 23, and further rotates the outer rotor 33 meshing with the inner rotor 34. Thus, the pressure chamber 50 formed between the outer rotor 33 and the inner rotor 34 sequentially moves in the clockwise direction.
Since the rotors 33 and 34 are eccentrically provided, the volume of the pressure chamber 50 gradually increases on the left side in FIG. 3 and gradually decreases on the right side in FIG. Thereby, fuel is sucked from the suction port 41 and discharged to the discharge port 39. Therefore, the fuel in the fuel tank is sucked from the suction port 42, pressurized by the pump unit, passes through the housing 10, and
Fuel is delivered from 4.

Generally, the fuel discharged from the discharge port 14 is 2 to 4 kg by a pressure regulator (not shown).
f / cm ^2, and the fuel pressure in the discharge passage 40 is maintained at approximately ² to 4 kgf / cm ² . Therefore, the clearance between the shaft 21 and the bearing 37 and the shaft 2
In order to allow a part of the fuel to leak from the high pressure side to the low pressure side through the gap between
And try to push to the left. However, since the pressure balance holes 23g and 23h are formed in the coupling 23, the pressures in the chambers 38a and 36a are equalized, and the coupling 23 is not pressed against the pump cover 36.

In this embodiment, the pressure balance holes 23g and 23h penetrating in the axial direction of the coupling 23 are provided.
Since it is sufficient that the pressure in the chamber 38a and the chamber 36a on both sides of the coupling 23 can be balanced, the present invention does not need to be a hole and may be provided with a groove or the like. It is desirable to adjust the size and the number of them.

[0021]

As described above, according to the gear pump of the present invention, a pressure balance passage connecting the high pressure side and the low pressure side is formed in the coupling connecting the drive shaft and the inner rotor. Are balanced, and the pressing force in one direction of the coupling is reduced, so that there is an effect that wear of the sliding portion is reduced.

[Brief description of the drawings]

FIG. 1 is a partial sectional view of a vehicle fuel pump according to an embodiment to which the present invention is applied.

FIG. 2 is a partially cutaway plan view of a vehicle fuel pump according to an embodiment to which the present invention is applied.

FIG. 3 is a sectional view taken along line AA shown in FIG. 2;

FIG. 4 is a partial perspective view of a vehicle fuel pump according to an embodiment to which the present invention is applied.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vehicle fuel pump 10 Housing 21 Shaft 23 Coupling 23a Parallel two surface part (first fitting part) 23b Parallel two surface part (first fitting part) 23d Projecting part (second fitting part) 23e Projecting part (second Fitting portion) 23g Pressure balance hole (pressure balance passage) 23h Pressure balance hole (pressure balance passage) 30 Pump unit 31 Pump casing (casing) 32 Spacer 33 Outer rotor 34 Inner rotor 34a Inner wall groove 36 Pump cover (casing) 37 Bearing 38 Bush 39 Discharge port 40 Discharge passage 41 Suction port 42 Suction port 50 Pressure chamber

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) F04C 2/08-2/28 F04C 11/00-15/04 321

Claims (2)

(57) [Claims] 1. An outer rotor having internal teeth formed therein, an inner rotor housed in the outer rotor and having external teeth meshing with the internal teeth formed therein, and the outer rotor and the inner rotor being eccentrically rotatable with each other. A casing that accommodates and forms the side walls of a plurality of pressure chambers formed between the inner teeth and the outer teeth, and rotates the outer rotor and the inner rotor to move the pressure chambers while changing the volume thereof. A drive shaft, a suction port provided in communication with the pressure chamber of increasing capacity, a discharge port provided in communication with the pressure chamber of decreasing capacity, and an end of the drive shaft. A coupling having a first fitting portion to be fitted and a second fitting portion engaged with an inner wall groove of the inner rotor; and a low pressure side to a high pressure side provided on a low pressure side of the coupling.
Pressure balance chamber for applying fluid pressure to the coupling
With the door, said coupling, a high pressure side of the periphery of the coupling
A gear pump having a pressure balance passage communicating with the pressure balance chamber . 2. The pressure balance passage, wherein:
Communication holes open at the high-pressure end and low-pressure end of the ring
The gear pump according to claim 1, wherein