JPH074377A - Fuel pump - Google Patents

Abstract

PURPOSE:To reduce load torque at the rotating time of an impeller so as to improve pump efficiency by changing the shape of the pressure-regulating communicating hole of the impeller. CONSTITUTION:A fuel pump is provided with a disc-shaped impeller 10 rotatably built in a pump housing and provided with numerous blade grooves 11 at the outer peripheral part on both front and rear faces; sealing clearances provided between the respective front and rear faces of the impeller 10 and the pump housing wall surface facing the respective front and rear faces; and pressure- regulating communicating holes 24 formed at the impeller 10 so as to communicate the sealing clearances on both front and rear sides. The communicating hole 24 of the impeller 10 is formed into slit shape long in the circumferential direction of the impeller 10 and short in the radial direction of the impeller 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel pump mainly used as an in-tank type fuel supply pump for an electronically controlled fuel injection device for automobiles.

[0002]

2. Description of the Related Art A conventional example of an in-tank type fuel pump will be described with reference to FIG. 3 showing a cross-sectional view of its pump portion. The fuel pump has a cylindrical motor housing 1
The motor unit 2 is composed of a DC motor incorporated in the above, and the pump unit 3 is incorporated in the lower portion thereof. The motor unit 2 includes an armature 5 coaxial with the motor housing 1, a magnet 6 attached to an inner peripheral surface of the motor housing 1, a pump cover 7 attached to a lower end portion of the motor housing 1, and a motor (not shown). The motor cover is attached to the upper end of the housing 1. The motor cover is provided with a fuel outlet for connecting a fuel supply pipe to an automobile engine.

In the pump portion 3, the lower portion of the shaft 5a of the armature 5 is rotatably supported by the pump cover 7 via a bearing 8, and the lower end portion of the shaft 5a extends to the pump portion 3. The pump unit 3 is driven by the motor unit 2 in a cascade type (also called a Wesco type or a circumferential flow type).
The upper and lower impellers 10 each have a disk shape and have blade grooves 11 on the outer peripheral portions of both front and back surfaces thereof.

A pump housing for accommodating the impeller 10 is composed of the pump cover 7, a center plate 13 and a pump body 14 which are located below the pump cover in order. And the pump cover 7 and the center plate 1
3 and the center plate 13 and the pump body 14
And the impellers 10 are housed between them. Each impeller 10 is connected to the shaft 5a of the armature 5 by fitting.

Each impeller 1 is attached to the pump housing.
The upper and lower two-stage fuel passages 15 each having a substantially C shape corresponding to the outer peripheral portion of 0 are formed. A lower end of the fuel passage 15 communicates with a fuel intake port 17 provided in the pump body 14 and an end thereof communicates with a connection hole 18 provided in the center plate 13. The upper end of the fuel passage 15 communicates with the connection hole 18 of the center plate 13, and the end of the upper fuel passage 15 communicates with the inside of the motor housing 1 through a fuel outlet hole 19 provided in the pump cover 7. . The fuel inlet 17, the connection hole 18, and the fuel outlet hole 19 are shown to be on the same line in the drawing, but actually have a positional relationship in which they are displaced from each other by a predetermined angle.

A leak-preventing gap 20 is provided between the front and back surfaces of the impeller 10 (upper and lower surfaces in the drawing) and the wall surface of the pump housing facing the respective surfaces. The gap 20 is set to be a slight gap in which the fuel is not leaked from the fuel passage 15 while ensuring the smooth rotation of the impeller 10.

In the fuel pump, an impeller 10 of the pump unit 3 rotates together with the armature 5 by driving the motor unit 2 by using a battery (not shown) of an automobile as a power source. As a result, the fuel in the fuel tank is pumped up from the fuel intake port 17 to the fuel passage 15 below. The pumped fuel is pressurized by the rotation of the impeller 10 while passing through the lower fuel passage 15 and then the upper fuel passage 15, enters the motor housing 1 through the fuel outlet hole 19, and passes through the motor housing 1. Then, the fuel is discharged from the fuel discharge port.

Next, the impeller 1 in the fuel pump
The main configuration of 0 will be described in detail with reference to the explanatory view of FIG. 4 in addition to FIG. 4 (a) is a surface view of the impeller,
(B) is the sectional view. The impeller 10 is provided with, for example, circular pressure regulating communication holes 22 for communicating the leakage preventing gaps 20 on both sides of the impeller 10, for example, six on each of two circles, for a total of 12 at a predetermined interval. (See FIG. 4 (a)). The pressure adjusting communication hole 22 serves to adjust the pressure so as to eliminate the pressure difference between the leakage preventing gaps 20 on both sides of the impeller, thereby preventing the impeller 10 from being biased to one wall surface of the pump housing. By reducing the frictional resistance of the impeller 10, pump efficiency, durability, etc. can be improved. The diameter d of the communication hole 22 is, for example, about 2 mm in actual size. A fuel pump in which the impeller 10 having the pressure regulating communication hole 22 as described above is incorporated is disclosed in, for example, JP-A-1-53089.

[0009]

With the conventional example described above,
Indicates that the pressure regulating communication hole 22 of the impeller 10 has a circular shape.
The so-called communication hole 22 in the radial direction of the impeller 10
Has a large opening. Therefore, when the impeller 10 rotates
The load torque received (also called rotational load) is large,
The efficiency is low. This means that the motor
It hinders current flow. For the load torque of the impeller 10
Details will be described. The load torque is the shaft of the impeller 10.
The distance from the center to the axis of the communication hole 22 is R,
Communication area is S ₁And R × S₁Proportional to the value of.
Communication area S here₁Is the hole diameter (ie impeller half
The opening amount in the radial direction) was d, and the thickness of the impeller 10 was t.
When S₁= D × t, the area of the communication hole 22
This is a cross-sectional area in the radial direction of the impeller. Therefore, the load torque
To reduce power consumption, the communication area S₁Should be small,
Communication area S₁Is S₁= D × t, the thickness t is the same.
If it is 1, the opening amount d may be reduced.

Therefore, the present invention has been made to solve the above-mentioned problems, and the purpose thereof is to reduce the load torque when the impeller is rotated by changing the shape of the pressure regulating communication hole of the impeller, thereby improving the pump efficiency. It is to provide a fuel pump that can be improved.

[0011]

DISCLOSURE OF THE INVENTION The present invention for solving the above-mentioned problems includes an impeller having a disk shape rotatably incorporated in a pump housing and having a large number of blade grooves on the outer peripheral portions of both front and back surfaces thereof. A leak-preventing gap provided between the front and back surfaces of the impeller and the wall surface of the pump housing facing the respective faces, and a pressure-regulating communication that communicates with the leak-preventing gaps formed on the impeller on both sides of the impeller. In a fuel pump having a hole and increasing the fluid pressure by rotating the impeller by driving a motor unit, the pressure regulating communication hole of the impeller is formed in a slit shape long in the impeller circumferential direction and short in the impeller radial direction. Has been done.

[0012]

According to the above means, the pressure regulating communication hole of the impeller is formed in a slit shape that is long in the impeller circumferential direction and short in the impeller radial direction, so that the pressure regulating effect is not reduced as compared with the circular communication hole. The area can be secured and the opening amount in the radial direction of the impeller can be reduced, which reduces the communication area in the radial direction of the impeller, which in turn can reduce the load torque during rotation of the impeller.

[0013]

EXAMPLES Examples of the present invention will be described. Since this example is a modification of a part of the above-mentioned conventional example, the modified part will be described in detail, and the same or equivalent configuration as that of the conventional example will be designated by the same reference numeral in the drawings and redundant description will be given. Is omitted. The main structure of the impeller 10 will be described in detail with reference to the explanatory view of FIG. 1 in addition to FIG. Figure 1
(A) is a surface view of an impeller and (b) is a sectional view thereof. In the impeller 10 of this example, the pressure regulating communication hole 24
Is formed in place of the circular communication hole 22 of the conventional example.
The communication hole 24 is formed in a slit shape that is long in the impeller circumferential direction and short in the impeller radial direction. The impeller 10 having the slit-shaped communication hole 24 is assembled in a fuel pump in the same manner as in the conventional case, as shown in FIG.

According to this fuel pump, the pressure regulating communication hole 24 of the impeller 10 has a slit shape that is long in the circumferential direction of the impeller and short in the radial direction of the impeller, so that the pressure regulating effect is greater than that of the circular communication hole 22. It is possible to secure an opening area that does not reduce the opening ratio and reduce the opening amount b in the impeller radial direction.

Looking at the load torque of the impeller 10,
The load torque is proportional to the value of R × S, where R is the distance from the shaft center of the impeller 10 to the center of the pressure regulating communication hole 24 in the radial direction of the impeller and S is the communication area of the communication hole 24. Here, the communication area S is an area represented by S = b × t, where b is an opening amount in the impeller radial direction and t is a thickness of the impeller 10, and is a cross-sectional area of the communication hole 22 in the impeller radial direction. is there. As compared with the circular communication hole 22 (see FIG. 4) of the conventional example, if the opening area, distance R, and thickness t of both communication holes 22 and 24 are the same, the impeller radius of the slit-shaped communication hole 24 is the same. Opening amount b in the direction is circular communication hole 22
Is smaller than the opening amount d in the impeller radial direction. Therefore,
Since the slit-shaped communication hole 24 is used, the communication area S becomes smaller than the communication area S ₁ of the circular communication hole 22, and thus the load torque is reduced. By thus reducing the load torque, the pump efficiency is improved. This improvement in pump efficiency makes it possible to reduce the motor current.

FIG. 2 is a characteristic diagram showing the relationship between the voltage V applied to the motor unit 2, the discharge flow rate Q of the fuel pump, and the drive current I of the motor unit 2. The horizontal axis in the figure represents the applied voltage V (V), the left vertical axis represents the discharge flow rate (L / H), and the right vertical axis represents the current I (A). The straight line indicated by the solid line A in the figure indicates that the discharge flow rate Q increases in proportion to the applied voltage V. The solid line B in the figure shows the characteristics of the current I of the example product, and the current I of the conventional product shown by the dotted line C.
It can be seen that the current value is lower than the characteristics of.

[0017]

According to the fuel pump of the present invention, since the pressure regulating communicating hole of the impeller is formed in a slit shape long in the impeller circumferential direction and short in the impeller radial direction, the pressure regulating effect is higher than that of the circular communicating hole. It is possible to reduce the opening amount in the radial direction of the impeller without lowering the impeller radius, which reduces the communication area in the radial direction of the impeller, which in turn reduces the load torque during rotation of the impeller, improving pump efficiency and further improving the motor efficiency. It is possible to reduce the current of parts.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an impeller of an embodiment.

FIG. 2 is a characteristic diagram showing a relationship among an applied voltage, a discharge flow rate, and a current.

FIG. 3 is a sectional view showing a pump portion of a fuel pump.

FIG. 4 is an explanatory view showing a conventional impeller.

[Explanation of symbols]

 10 Impeller 11 Blade groove 24 Communication hole

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuo Nomura 1-1-1-1, Kyowa-cho, Obu-shi, Aichi Aisan Industry Co., Ltd.

Claims (1)

[Claims] 1. An impeller having a disk shape rotatably incorporated in a pump housing and having a large number of blade grooves on the outer peripheral portions of the front and back surfaces thereof, and the front and back surfaces of the impeller and the respective surfaces facing each other. A leak preventive gap provided between the impeller and a wall surface of the pump housing, and a pressure adjusting communicating hole formed in the impeller and communicating with the leak preventive gaps on both front and back sides of the impeller. A fuel pump for increasing the fluid pressure by rotating the fuel pump, wherein the pressure regulating communication hole of the impeller is formed in a slit shape that is long in the circumferential direction of the impeller and short in the radial direction of the impeller.