Electric fuel pump

An electric fuel pump includes a housing having an oil inlet and an oil outlet, an impeller, a stator unit mounted in the housing and including a stator and a starter terminal set connected to the stator, a packaging adhesive encapsulating the stator and the starter terminal set to create an oil guide passage in communication between the oil inlet and the oil outlet, and a rotor unit mounted in the housing and including a rotor rotatably mounted in the stator and a rotating shaft mounted in the rotor and connected with the impeller. When the stator unit is electrically conducted, the rotor unit drives the impeller to draw a fuel oil into the oil guide passage. When the fuel oil goes through the oil guide passage, the stator and the starter terminal set are well protected by the packaging adhesive and prohibited from contacting the fuel oil.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to pump technology and more particularly, to an electric fuel pump that offers high durability.

2. Description of the Related Art

An electric fuel pump is adapted for transporting a certain pressure fuel oil through a piping to a carburetor so that the engine can be smoothly started to output torque. In conventional electric fuel pump system, an armature assembly and a pump unit are respectively placed in a yoke pipe assembly and then connected together. When the armature assembly is started to rotate, an impeller of the pump unit is rotated to boost the pressure of the fuel oil and to force the pressure-increased fuel oil out of the pump unit through the yoke pipe assembly to the carburetor via an oil outlet of a top cover assembly.

However, in the conventional electric fuel pump system, the armature assembly is kept in direct contact with the fuel oil. After a long use, the armature assembly is vulnerable to fuel corrosion, causing structural damage and affecting the performance. Thus, the structural durability of the conventional electric fuel pump system is not good enough.

SUMMARY OF THE INVENTION

The present invention has been accomplished under the circumstances in view. It is the main object of the present invention to provide an electric fuel pump, which avoids fuel oil damage to the structure, prolonging the lifespan and enhancing the durability.

To achieve this and other objects of the present invention, an electric fuel pump comprises a housing, a pressure booster, a stator unit and a rotor unit. The housing defines an oil inlet and an oil outlet. The pressure booster is mounted in the housing, comprising an impeller seat and an impeller. The impeller seat comprises an oil hole. The impeller is rotatably mounted in the impeller seat between the oil inlet of the housing and the oil hole of the impeller seat, and adapted for sucking a fuel oil into the housing to increase its pressure and then forcing the high-pressure fuel oil out of the impeller seat through the oil hole. The stator unit is mounted in the housing, comprising a stator and a starter terminal set. The starter terminal set is mounted at one end of the stator and encapsulated with the stator in a packaging adhesive so that an oil guide passage is created inside the stator and the starter terminal set. The oil guide passage has two opposite ends thereof respectively connected to the oil outlet of the housing and the oil hole of the impeller seat of the pressure booster so that the fuel oil can be delivered from the oil hole of the impeller seat through the oil guide passage to the oil outlet of the housing. The rotor unit is mounted in the housing, comprising a rotor, a magnet and a rotating shaft. The rotor is rotatably mounted in the stator. The magnet is mounted between the stator and the rotor. The rotating shaft extends through the rotator, having one end thereof rotatably inserted into the stator unit and an opposite end thereof connected with the impeller of the pressure booster. Thus, when the stator unit is electrically conducted, the rotating shaft of the rotator unit drives the impeller of the pressure booster to rotate.

Thus, the electric fuel pump of the present invention uses the packaging adhesive to protect the stator and the starter terminal set, prohibiting the stator and the starter terminal set from contacting the fuel oil when the fuel oil is being delivered through the oil guide passage. Thus, the invention effectively prolongs the lifespan of the electric fuel pump and enhances the durability of the electric fuel pump while maintaining a stable operating performance.

In the present invention, the stator comprises a stator iron core. The stator iron core comprises a plurality of magnetically permeable members equiangularly spaced from one another so that a diversion space is defined between each two adjacent magnetically permeable members. The starter terminal set comprises a terminal block. The terminal block is connected to one end of the stator iron core, comprising an axle tube and a plurality of draft tubes spaced around the axle tube. The rotating shaft is rotatably inserted into the axle tube. The draft tubes are respectively connected to the diversion spaces of the stator iron core. Thus, the draft tubes of the terminal block and the diversion spaces of the stator iron core form the oil guide passage.

In the present invention, the stator iron core of the stator comprises at least one positioning rod; the terminal block comprises at least one positioning groove respectively engaged with the at least one positioning rod of the stator iron core, enhancing installation convenience.

DETAILED DESCRIPTION OF THE INVENTION

Referring toFIGS. 1 and 2, an electric fuel pump10in accordance with the present invention is shown. The electric fuel pump10comprises a housing20, a pressure booster30, a stator unit40, and a rotor unit80.

The housing20comprises a tubular housing body21, an inlet end cap22, an outlet end cap23, and a pair of power supply terminals24. The inlet end cap22is fastened to one end of the tubular housing body21, comprising an oil inlet25cut through opposing front and inner ends thereof and an arc runner26located the inner end. The arc runner26has one end thereof connected to the oil inlet25. The outlet end cap23is fastened to an opposite end of the tubular housing body21, comprising an oil outlet27cut through opposing front and inner ends thereof. The power supply terminals24are mounted at the outlet end cap23, as shown inFIG. 4, for connection to an external power source (not shown).

The pressure booster30is mounted in the tubular housing body21of the housing20, comprising an impeller seat31and an impeller32. The impeller seat31comprises a rear axle hole33located at the center thereof, and an oil hole34spaced around the rear axle hole33and disposed in communication with the oil inlet25of the housing20. The impeller32is rotatably mounted in the impeller seat31between the oil inlet25of the housing20and the oil hole34of the impeller seat31.

As illustrated inFIGS. 3 and 4, the stator unit40comprises a starter terminal set50consisting of a terminal block51and a pair of starter terminals52. The terminal block51comprises a back cover53, a front cover54, and a circuit board55.

The back cover53comprises three positioning grooves532equiangularly located on one side thereof, an axle tube534perpendicularly extended from an opposite side thereof at the center, four draft tubes536equiangularly spaced around the axle tube534, and a pair of rear pin holes538.

The front cover54comprises a first through hole542located at the center, and four first coupling holes544equiangularly spaced around the first through hole542. The front cover54is assembled with the back cover53by coupling the first through hole542and the first coupling holes544to the axle tube534and draft tubes536of the back cover53respectively with a metal connection ring56set between the front cover54and the back cover53around the border area. The front cover54further comprises a pair of front pin holes546.

The circuit board55is mounted between the front cover54and the back cover53, comprising a second through hole552located at the center and four second coupling holes554equiangularly spaced around the second through hole552. The second through hole552and second coupling holes554of the circuit board55are respectively coupled to the axle tube534and draft tubes536of the back cover53. The circuit board55further comprises two conducting pins57that are inserted with respective opposing front and rear ends thereof into the front pin holes546of the front cover54and the rear pin holes538of the back cover53.

The starter terminals52are mounted on one side of the front cover54opposite to the back cover53, and electrically connected with respective one ends thereof to the power supply terminals24of the housing20and respective opposite ends thereof to the pins57of the circuit board55.

On the other hand, the stator unit40further comprises a stator60. The stator60comprises a stator iron core61and six coil sets64. The stator iron core61comprises three positioning rods62equiangularly located at one end thereof opposite to the pressure booster30, and six magnetically permeable members63equiangularly spaced around the inner perimeter thereof and respectively surrounded by one respective coil set64.

When assembling the stator60and the starter terminal set50, insert the positioning rods62of the stator iron core61into the respective positioning grooves532of the back cover53of the terminal block51, and then solder one respective lead-out end (not shown) of each coil set64to the pins57of the circuit board55of the terminal block51. After assembled the stator60and the starter terminal set50, encapsulate the stator60and the starter terminal set50with a packaging adhesive70using insert molding technology. At this time, the packaging adhesive70seals up the inner and outer perimeters of the stator iron core61and the coil sets64, causing formation of a diversion space65between each two adjacent magnetically permeable members63. The starter terminal set50allows the overall outer perimeter of the terminal block51to be sealed up by the packaging adhesive70, leaving the starter terminals52partially exposed to the outside of the packaging adhesive70for connection to the power supply terminals24of the housing20. At this time, the draft tubes536are kept open. Thus, as shown inFIG. 4, four diversion spaces65in the stator iron core61are respectively connected with the four draft tubes536of the terminal block51, creating an oil guide passage42that has one end thereof disposed in communication with the oil hole34of the impeller seat31and an opposite end thereof disposed in communication with the oil outlet27of the housing20.

The rotor unit80is mounted in the tubular housing body21of the housing20, comprising a bearing seat81, a rotor82, a magnet83and a rotating shaft84. The bearing seat81is abutted against one end of the packaging adhesive70, comprising a front axle hole812located at the center of one end thereof and connected to the axle tube534of the back cover53of the terminal block51and four pilot holes814spaced around the front axle hole812and respectively connected to the draft tubes536of the back cover53of the terminal block51. The bearing seat81further comprises a terminal slot816for accommodating the starter terminals52of the stator unit40. The rotor82is mounted in the stator60and surrounded by the magnetically permeable members63of the stator iron core61. The magnet83is mounted on the outer perimeter of the rotor82to face toward the magnetically permeable members63of the stator iron core61. The rotating shaft84is mounted in the rotor82, having one end thereof inserted through and supported on a first axle bearing85in the rear axle hole33of the impeller seat31and then connected with the impeller32and an opposite end thereof inserted through the axle tube534of the terminal block51into a second axle bearing86and supported by the second axle bearing86in the front axle hole812of the bearing seat81.

When the power supply terminals24and the starter terminals52are electrically conducted to transmit electricity through the coil sets64, a rotating magnetic field is generated. This rotating magnetic field being created by the stator60induces an electric current in the rotor82resulting in another magnetic field. This induced magnetic field from the rotor82interacts with the rotating magnetic field, causing the rotor82to rotate. During rotation of the rotor82, the rotating shaft84drives the impeller32to rotate, causing generation of a vacuum suction force that draws a fuel oil from the oil inlet25of the housing20into the inside of the housing20, enabling the fuel oil to flow through the arc runner26of the inlet end cap22into the impeller32. At this time, the pressure of the fuel oil is increased subject to rotation of the impeller32at a high speed. The high pressure fuel oil is then guided to flow through the oil hole34of the impeller seat31to the oil guide passage42of the stator unit40and then to flow out of the oil guide passage42of the stator unit40through the pilot holes814of the bearing block81to the outlet end cap23of the housing20, and finally to flow out of the housing20through the oil outlet27of the outlet end cap23.

When the fuel oil is flowing through the oil guide passage42of the stator unit40, the starter terminal set50and the stator60are well protected by the packaging adhesive70, prohibiting the circuit board55and the coil sets64from contacting the fuel oil. Thus, the invention achieves the targets of prolonging the lifespan of the electric fuel pump and enhancing the durability of the electric fuel pump while maintaining a stable operating performance.