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  Fuel pumpRelated Patent Categories: Pumps, Motor Driven, Electric Or Magnetic Motor, Rotary Motor And Rotary Nonexpansible Chamber Pump, Having Additional Means To Remove Heat From Pump Or MotorThe Patent Description & Claims data below is from USPTO Patent Application 20060204385. Brief Patent Description - Full Patent Description - Patent Application Claims
CROSS REFERENCE [0001] This application claims priority to Japanese Patent application number 2005-67677, filed on Mar. 10, 2005, the contents of which are hereby incorporated by reference as if fully set forth herein. BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present invention relates to a fuel pump for drawing in a fuel such as gasoline etc., increasing the pressure thereof, and discharging the pressurized fuel. [0004] 2. Description of the Related Art [0005] A known fuel pump generally comprises a housing, a pump casing attached to a lower end portion of the housing, and a motor cover attached to an upper end portion of the housing. An intake hole is provided in the lower surface of the pump casing. A discharge port is provided in the upper surface of the motor cover. The discharge port protrudes from the upper surface of the motor cover. A motor is accommodated inside a motor chamber defined by the housing, pump casing, and motor cover (i.e., space inside the housing). The lower end of the motor shaft is rotatably supported on the pump casing, and the upper end of the motor shaft is rotatably supported on the motor cover. An impeller is rotatably disposed within the pump casing. The impeller is connected with the lower end of the motor shaft. When the motor rotates, the impeller also rotates and a fuel is drawn into the pump casing from the intake hole. The pressure of the fuel drawn into the pump casing rises and the fuel is discharged from the discharge port through the motor chamber. [0006] This type of fuel pump is usually disposed within the fuel tank. As a result, the length of the fuel pump in the axial direction is restricted by the shape of the fuel tank. In recent years, fuel tanks have tended to become flatter. In particular, flattened fuel tanks for automobiles are designed to enable the enlargement of space inside the automobile, without increasing the size of the automobile body. Therefore, there is need for the axial length of the fuel pump to be shorter as well. [0007] In the conventional fuel pump, a discharge port protrudes from the upper surface of the motor cover, and the discharge port is inserted into a fuel pipe (e.g., hose, etc.). Therefore, the diameter of the discharge port is made less than the diameter of the fuel pipe. On the other hand, because the pressurized fuel flows from the discharge port into the fuel pipe, the discharge port and the fuel pipe have to be strongly joined. Thus, the surface area of the joint portion of the discharge port and the fuel pipe has to be somewhat increased to obtain a strong joint thereof. Since the diameter of the discharge port is less than the diameter of the fuel pipe, the length of the discharge port has to be increased to a certain extent in order to join strongly the discharge port and the fuel pipe. For this reason, in the conventional fuel pumps, it is difficult to shorten the discharge port. Therefore, the length of the fuel pump in the axial direction is increased by the length of the discharge port. [0008] Japanese Laid-Open Patent Publications No. 2004-293526 and 2003-286924 disclose fuel pumps in which the discharge port is formed concavely from the upper surface of the motor cover. However, in those fuel pumps, the discharge port is disposed in the center of the motor cover (i.e., on a central axis line of the fuel pump). Because a bearing that supports the motor shaft is disposed in the center of the motor cover, the discharge port has to be disposed above the bearing. As a result, the length of such fuel pump in the axial direction is structurally also difficult to decrease. SUMMARY OF THE INVENTION [0009] Accordingly, it is one object of the present teachings to provide a fuel pump that makes it possible to decrease the length of the fuel pump in the axial direction, thereby improving installation ability on a fuel tank. [0010] In one aspect of the present teachings, fuel pump may comprise a housing, a motor disposed within the housing, and a motor cover attached to one end of the housing. The motor may include a motor shaft. The motor cover may comprise a bearing retaining portion and a discharge port. The bearing retaining portion retains a bearing that rotatably supports one end of the motor shaft. The discharge port may be formed concavely from the outer surface of the motor cover. A fuel pipe is inserted into the discharge port. When the motor shaft rotates, a fuel is drawn into the housing and discharged to the fuel pipe from the discharge port. The bearing retaining portion may be formed in a center of the inner surface of the motor cover. The discharge port may be disposed in a position shifted from the bearing retaining portion. [0011] In this fuel pump, the fuel pipe is inserted into the discharge port. Therefore, the diameter of the discharge port can be made larger than the outer diameter of the fuel pipe. Thus, the surface area of the joint portion of the fuel pipe and discharge port can be ensured even if the length of the discharge port is shorter than that of the protruding discharge port. Furthermore, because the discharge port is disposed in a position shifted from the bearing retaining portion, the bearing retaining portion and the discharge port can be disposed so as to overlap in the axial direction. As a result, the length of the fuel pump in the axial direction can be shortened and the installation ability on a fuel tank can be improved. [0012] Preferably, a fuel channel formed in the motor cover extends linearly from the inner surface of the motor cover toward the discharge port. Because channel resistance to the fuel flow from inside the housing to the discharge port is decreased, the pump efficiency can be increased. [0013] In another aspect of the present teachings, the motor may comprise a commutator and a brush that comes into contact with the commutator. The motor cover may comprise a brush retaining portion for retaining the brush. The brush retaining portion may be formed in the inner surface of the motor cover. Preferably, the brush retaining portion and the discharge port are arranged side by side in the circumferential direction, and the bearing retaining portion, discharge port, and brush retaining portion are arranged so as to overlap in the axial direction. [0014] In this fuel pump, because the brush retaining portion and discharge port are arranged side by side in the circumferential direction of the fuel pump, the brush retaining portion can be arranged in a position close to the axial center of the motor shaft. As a result, the commutator diameter is reduced and the circumferential speed of the commutator is decreased, thereby making it possible to suppress the wear on the brush. Furthermore, because the bearing retaining portion and the discharge port and the brush retaining portion overlap in the axial direction, the axial length of the fuel pump can be shortened. [0015] In the above-described fuel pumps, the wall that forms the bearing retaining portion can be shared with the wall that forms the discharge port. Alternatively, the wall that forms the discharge port can be shared with the wall that forms the brush retaining portion. Alternatively, the wall that forms the bearing retaining portion can be shared with the wall that forms the brush retaining portion. Sharing the walls that form the adjacent portions (i.e., bearing retaining portion, brush retaining portion, or discharge port) makes it possible to dispose the portions close to each other and to make the fuel pump compact in the radial direction. [0016] In another aspect of the present teachings, the motor cover may include a fuel discharge hole which is formed in the bottom surface of the discharge port. Preferably, a return check valve for opening and closing the fuel discharge hole is installed in the discharge port, and the return check valve is positioned on the outer side of the fuel pipe in a state where the fuel pipe is inserted into the discharge port. [0017] In this fuel pump, the fuel pipe and return check valve are disposed side by side in the axial direction of the fuel pump. Because the return check valve is not disposed inside the fuel pipe, the shape of the return check valve is not restricted by the shape of the fuel pipe and the diameter (i.e., seal diameter) of the return check valve can be increased. As a result, pressure sensitivity of the return check valve can be increased and the return check valve can be operated with good stability even when the stroke of the return check valve is small. Furthermore, because the stroke of the return check valve can be reduced, the length of the discharge port can be shortened. [0018] When the return check valve is installed in the discharge port, it is preferred that a guide for guiding the return check valve be further provided in the discharge port. With such a configuration, the return check valve is prevented from tilting inside the discharge port and operability of the return check valve can be ensured. [0019] These aspects and features may be utilized singularly or, in combination, in order to make improved fuel pump. In addition, other objects, features and advantages of the present teachings will be readily understood after reading the following detailed description together with the accompanying drawings and claims. Of course, the additional features and aspects disclosed herein also may be utilized singularly or, in combination with the above-described aspect and features. BRIEF DESCRIPTION OF THE DRAWINGS [0020] FIG. 1 schematically shows a fuel pump of a representative embodiment of the present teachings and a fuel filter that will be connected to the fuel pump. Continue reading... Full patent description for Fuel pump Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Fuel pump patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. 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