AU2009201350A1

AU2009201350A1 - External Inline LPG Fuel Pump

Info

Publication number: AU2009201350A1
Application number: AU2009201350A
Authority: AU
Inventors: Kyo Nam Choi; Kern Yong Kang; Chang Up Kim; An Sung Lee; Seung Mook Oh; Chul Woong Park
Original assignee: Korea Institute of Machinery and Materials KIMM
Current assignee: Korea Institute of Machinery and Materials KIMM
Priority date: 2009-04-07
Filing date: 2009-04-07
Publication date: 2010-10-21

Description

EXTERNAL INLINE LPG FUEL PUMP BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an external inline LPG fuel pump and, more particularly, to an external inline LPG fuel pump, in which even though LPG fuel is supplied to the fuel pump while a motor is driven, durability deterioration caused by the wearing of certain parts, including the bushing, the pumping part and the inside of the housing, is prevented to prolong the useful lifetime of the fuel pump and to reduce costs of repair and replacement involved with the fuel pump; a high-temperature LPG fuel discharged through an outlet port of the housing is cooled to reduce heat load and to improve durability of a device receiving the LPG fuel from the fuel pump; suction of the LPG fuel at an inlet port is improved to improve the efficiency of flow in the inlet port; and the fuel flows into the fuel pump through grooves to prevent a carrier from being pushed to one side by fuel pressure and therefore from coming into contact with first plate, to maintain equal pressure at both sides and to prevent noise and damage caused by friction when the carrier rotates. 2. Description of the Related Art In general, a pump is a device used to move a fluid by putting energy. Types of pumps typically include a turbo pump, a positive displacement pump and a special pump, among others. A turbo pump supplies kinetic energy to a fluid by rotation of an impeller. A positive pump sucks a fluid and discharges the fluid to move, by periodically changing its special volume. Special pumps apply the other methods. Among the aforementioned pumps, a positive displacement pump is used as an automobile fuel pump because oil pressure is very high while an amount of oil used is small. A Liquid Phase LPG Injection (LPLI) method has been applied to use LPG, which is environmentally friendly fuel, as automobile fuel. A conventional method has used an internal pump which is installed in a fuel tank for the LPLI. However, when the internal pump is out of order, not only the internal pump but also the fuel tank also needs to be replaced. Due to this problem, an external fuel pump to be installed in a fuel line has been proposed. In the external fuel pump, a carrier is positioned to rotate inside a case and to transfer fuel admitted to the fuel pump. The carrier rotated by a motor transfers the fuel admitted to the fuel pump to one side. (The conventional art described below uses a rotary vane as a carrier.) A conventional external fuel pump pumps LPG fuel to be transferred to an engine, by driving a shaft positioned at the motor. A bearing to rotate the shaft at its position, without being shaken, is installed to be connected to an inner surface of the fuel pump. However, when the conventional external fuel pump is used for a long time, the bearing seriously wears away because friction is continuously caused between the bearing and the inner surface of the fuel pump by the rotation of the shaft. Consequently, a rotation force of the motor decreases, thereby lowering the efficiency of the fuel pump.

Moreover, the wearing of the bearing increases maintenance costs including repair and replacement, thereby decreasing the productivity of and demand for the external fuel pump. Moreover, when the fuel admitted to the fuel pump is transferred to one side, the fuel pressure increases to push the rotary vane to the other side (which is opposite to the one side to which the fuel is transferred). Then, the rotary vane comes into contact with first plate and continuously rotates, thereby increasing a frictional force to cause noise and damage. SUMMARY OF THE INVENTION It is, therefore, an object of the present invention to provide an external inline LPG fuel pump in which bushings are respectively positioned about first and second shafts of a motor to be secured inside a housing; a ball is completely connected to an end of the first shaft in one body, to prevent the motor from being shaken by the bushings; and another ball is inserted into an end of the second shaft, to secure the motor, whereby even though LPG fuel is supplied to the fuel pump when the motor is driven, durability deterioration caused by the wearing of a bushing, a pumping part and the inside of a housing is prevented to prolong the useful lifetime of the fuel pump and to reduce costs of repair and replacement involved with the fuel pump. Another object of the present invention is to provide an external inline LPG fuel pump in which a case is formed to install a housing inside; and a partition is installed inside the case, whereby a high-temperature LPG fuel discharged through an outlet port of the housing is cooled to reduce heat load and to improve durability of a device receiving the LPG fuel from the fuel pump.

Another object of the present invention is to provide an external inline LPG fuel pump in which LPG fuel flows into the fuel pump in a lateral direction so as to be inline transferred by a carrier, whereby suction of the LPG fuel through an inlet port is improved to increase the efficiency of flow in the inlet port. Another object of the present invention is to provide an external inline LPG fuel pump in which a carrier comprises: a through-aperture formed in the center of the carrier so as to be operatively connected to a driving shaft of a motor; a round protrusion part formed at one side around the through-aperture; and a number of grooves formed in various shapes in a circumferential direction of the round protrusion part around the through-aperture, whereby LPG fuel flows into the fuel pump through the grooves to prevent the carrier from being pushed to one side by pressure of the fuel and therefore from coming into contact with first plate, to maintain equal pressure at both sides and to prevent noise and damage caused by friction when the carrier rotates. According to an aspect of the present invention, there is provided an external inline LPG fuel pump comprising: a housing having an inlet port positioned at one side of the housing and an outlet port positioned at the other side of the housing, to respectively admit and discharge LPG fuel; a pumping part positioned in the housing proximate to the inlet port, to pump the LPG fuel into the housing; a motor part positioned in the housing and including: a first shaft operatively connected to the pumping part and including an end formed with a ball in one body, to drive the pumping part, a second shaft formed at the opposite side to the first shaft and supported at the side of the housing proximate to the outlet port, an electric motor positioned between the first shaft and the second shaft, to generate a rotation force by electricity, and bushings each receiving the first and second shafts being in

A

contact with the housing to rotate by the electric motor secured inside the housing, in which another ball is inserted into an end of the second shaft being in contact with the housing proximate to the outlet port, to allow the second shaft to smoothly and stably rotate, without being shaken by the electric motor secured inside the housing; and a case being hollow to install the housing inside and including: a number of outlets formed to cool a high-temperature LPG fuel discharged through the outlet port of the housing after passing through the pumping part and the motor part, to reduce heat load and to discharge the LPG fuel outwardly, and a partition formed to circulate the high-temperature LPG fuel so as to be cooled through a number of channels. BRIEF DESCRIPTION OF THE DRAWINGS These and other aspects and advantages of the present invention will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings, in which: FIG. 1 is a sectional view illustrating an external LPG fuel pump according to a first embodiment of the present invention; FIG. 2 is an enlarged section view of "A" shown in FIG. 1; FIG. 3 is a sectional view illustrating a shaft into which a ball is inserted according to the first embodiment; FIG. 4 is an exploded perspective view illustrating an external LPG fuel pump according to a second embodiment of the present invention; FIG. 5 is a sectional view illustrating the external LPG fuel pump according to the second embodiment; FIG. 6 is a perspective view illustrating a first plate according to the second embodiment; FIG. 7 is an enlarged sectional view illustrating a housing formed with a ball in one body according to a third embodiment of the present invention; FIG. 8 is a perspective view illustrating a carrier according to the first embodiment; FIG. 9 is a plan view illustrating the carrier according to the first embodiment; FIG. 10 is a plan view illustrating a carrier according to a fourth embodiment of the present invention; FIG. 11 is a plan view illustrating a carrier according to a fifth embodiment of the present invention; and FIG. 12 is a plan view illustrating a carrier according to a sixth embodiment of the present invention. [Brief description of reference numbers of major elements] 1, 27: through-apertures 2: round protrusion part 3: groove 4: connection part 10: housing 11: inlet port 12: outlet port 13: guide partition 14: fuel channel 15: insertion opening 20: pumping part 21: carrier 22: first plate 23: second plate 24: roller 25: flow opening 26: transfer opening 28: cover 30: motor part 31: electric motor 32: first shaft 33: rotor 34: permanent magnet 35: ball 36: second shaft 40: bushing 50: case 51: outlet 52: partition 100: fuel pump DETAILED DESCRIPTION OF THE INVENTION In accordance with the present invention, the above and other aspects can be accomplished by an external inline LPG fuel pump comprising: a housing having an inlet port positioned at one side of the housing and an outlet port positioned at the other side of the housing, to respectively admit and discharge LPG fuel; a pumping part positioned in the housing proximate to the inlet port, to pump the LPG fuel into the housing; a motor part positioned in the housing and including: a first shaft operatively connected to the pumping part and including an end formed with a ball in one body, to drive the pumping part, a second shaft formed at the opposite side to the first shaft and supported at the side of the housing proximate to the outlet port, an electric motor positioned between the first shaft and the second shaft, to generate a rotation force by electricity, and bushings each receiving the first and second shafts being in contact with the housing to rotate by the electric motor secured inside the housing, in which another ball is inserted into an end of the second shaft being in 0 contact with the housing proximate to the outlet port, to allow the second shaft to smoothly and stably rotate, without being shaken by the electric motor secured inside the housing; and a case being hollow to install the housing inside and including: a number of outlets formed to cool a high-temperature LPG fuel discharged through the outlet port of the housing after passing through the pumping 5 part and the motor part, to reduce heat load and to discharge the LPG fuel outwardly, 7 and a partition formed to circulate the high-temperature LPG fuel so as to be cooled through a number of channels. The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. It will be understood that words or terms used in the specification and claims shall not be interpreted as the meaning defined in commonly used dictionaries. It will be further understood that the words or terms should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the technical idea of the invention, based on the principle that an inventor may properly define the meaning of the words or terms to best explain the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. The present invention may be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided as teaching examples of the invention. Therefore, it will be understood that the scope of the invention is intended to include various modifications and alternative arrangements within the capabilities of persons skilled in the art using presently known or future technologies and equivalents. FIG. 1 is a sectional view illustrating an external LPG fuel pump according to a first embodiment of the present invention, FIG. 2 is an enlarged section view of "A" shown in FIG. 1, FIG. 3 is a sectional view illustrating a shaft into which a ball is inserted according to the first embodiment, FIG. 4 is an exploded perspective view illustrating an external LPG fuel pump according to a second embodiment of the present invention, FIG. 5 is a sectional view illustrating the external LPG fuel pump according to the second embodiment, FIG. 6 is a perspective view illustrating a first plate according to the second embodiment, FIG. 7 is an enlarged sectional view illustrating a housing formed with a ball in one body according to a third embodiment of the present invention, FIG. 8 is a perspective view illustrating a carrier according to the first embodiment, FIG. 9 is a plan view illustrating the carrier according to the first embodiment, FIG. 10 is a plan view illustrating a carrier according to a fourth embodiment of the present invention, FIG. 11 is a plan view illustrating a carrier according to a fifth embodiment of the present invention, and FIG. 12 is a plan view illustrating a carrier according to a sixth embodiment of the present invention. (First Embodiment) As illustrated in FIG. 1, an external LPG fuel pump 100 according to the first embodiment of the present invention comprises: a housing 10, a pump part 20, a motor part 30 and a case 50. The housing 10 has an inlet port 11 and an outlet port 12. The inlet port 11 is formed at one side of the housing 10, to admit LPG fuel. The outlet port 12 is formed at the other side of the housing 10, to discharge the LPG fuel. The inlet port 11 of the housing 10 is connected to a fuel tank (not shown), and the outlet port 12 of the housing 10 is connected to a fuel injector (not shown) of an engine. That is, the fuel pump 100 according to the first embodiment is the external inline fuel pump to be installed in a fuel line which connects the fuel tank and the fuel injector. A space to install the pumping part 20 is formed inside the housing 10 proximate to the inlet port 11, and another space to install the motor part 30 is formed inside the housing 10 proximate to the outlet port 12. A guide partition 13 is formed to divide the inner space of the housing 10 into the pumping part 20 and the a motor part 30. A fuel channel 14 is formed in the guide partition 13, to transfer the LPG fuel to the motor part 30 through the pumping part 20. The fuel channel 14 is formed at a predetermined angle, so that the LPG fuel is smoothly transferred to the motor part 30 by rotation of the pumping part 20. The pumping part 20 comprises: a carrier 21, a roller 24, a first plate 22, and a second plate 23. The carrier 21 is connected to a first shaft 32 of the motor part 30 and is rotated by the first shaft 32, to pull the LPG fuel through the inlet port 11 of the housing 10 and to transfer the fuel inside the housing 10. The roller 24 is formed to surround an outer circumferential surface of the carrier 21. The first plate 22 is positioned at one side of the carrier 21 and the second plate 23 is positioned at the other side of the carrier 21. The carrier 21 may use a roller vane or gear rotor. In reference to FIGS. 2 and 3, an end of the first shaft 32 connected to the carrier 21 contacts the first plate 22. A ball is completely connected to the end of the first shaft 32 in one body, so that the end of the first shaft 32 has a round arc shape. When the first shaft 32 rotates, friction between the first shaft 32 and the first plate 22 is reduced by the round arc shaped end of the first shaft 32, to prevent wearing, damage, or the like. Further, an opening (not shown) is formed at one side of the first plate 22 connected to the end of the first shaft 32, so that the first shaft 32 is not displaced to its left or right side. After the second plate 23, roller 24, carrier 21 and first plate 22 are sequentially stacked to be connected to one another, the pumping part 20 is closed by a cover 28, to prevent these connected elements from being separated outwardly or to prevent the LPG fuel admitted into the housing 10 from being released outwardly through any other ways than the outlet port 12. 10 As illustrated in FIG. 8, the carrier 21 comprises: a through-aperture 1, a round protrusion part 2, a number of grooves 3, and a connection part 4. The through-aperture 1 is formed in the center of the carrier 21 to receive and be connected to the first shaft 32 of the motor part 30. The round protrusion part 2 is formed at one side around the through-aperture 1. The grooves 3 are formed in a circumferential direction of the round projection part 2 around the through-aperture 1, to apply equal pressure to both sides and therefore to prevent noise and damage caused by friction when the carrier 21 is pushed to any one side by pressure of the fuel and thus it comes into contact with first plate. The connection part 4 is formed at an outer circumferential side of the carrier 21, to receive a rotation member (not shown) formed to reduce the friction of the outer circumferential side of the carrier 21 when the carrier 21 rotates. The connection part 4 protrudes upwardly facing an outer edge of the round protrusion part 2 and guides the admitted fuel to flow into the grooves 3. The round protrusion part 2 is formed to protrude upwardly in the middle of the top of the carrier 21, and the through-aperture 1 is formed in the middle of the round protrusion part 2, to receive/be connected to the driving shaft of a motor. The round protrusion part 2 protrudes by a predetermined height so that the grooves 3 are formed in the circumferential direction. The grooves 3 are each formed inwardly from an outer circumferential edge of the round protrusion part 2, and the fuel admitted into the fuel pump flows through the grooves 3. The grooves 3 are formed on the top surface of the round protrusion part 2 so that the fuel flows into the grooves 3 and the pressure inside the grooves 3 increases, to push the carrier 21 to the opposite side on which the grooves 3 are formed.

That is, when the fuel flows into the fuel pump, the fuel is transferred to one side by the carrier 21. Since high pressure applies in the direction opposite to the direction in which the fuel is transferred, the fuel pushes the carrier 21 to the other side. Then, the carrier 21 comes in contact with first plate positioned outside. As a result, a frictional force between the carrier 21 and first plate increases by rotation of the carrier 21 and this causes noise and damage. In this regard, the grooves 3 have the function of pushing the carrier 2 to the opposite side on which the grooves 3 are formed, by increasing the pressure inside of the grooves 3. To prevent the carrier 21 from being pushed to one side, the grooves 3 are formed to maintain equal pressure in both sides against the pressure of the transferred fuel, so that the carrier 21 does not come into contact with first plate, thereby preventing noise and damage. As illustrated in FIG. 9, a number of the grooves 3 are formed in a circumferential direction on the top surface of the round protrusion part 2. Each of the grooves 3 is formed inwardly from the outer circumferential edge of the round protrusion part 2 towards an inner circumferential edge of the round protrusion 2, at a predetermined space (from the inner circumferential edge of the round protrusion 2, i.e., the through-aperture 1). The grooves 3 are formed in a spiral shape taken as a whole. The groove 3 is formed to be progressively narrower, in its width, from the outer circumferential edge of the round protrusion 2 towards the inner circumferential edge of the round protrusion part 2, so that the pressure of the fuel flowing into the grooves 3 increases to push the carrier 21 to the opposite side on which the grooves 3 are formed. The pressure of the fuel most increases in the most inner side of the groove 3.

The motor part 30 positioned in the housing 10 comprises: a first shaft 32, a second shaft 36 and an electric motor 31. The first shaft 32 is connected to the pumping part 20 and includes an end formed with a ball in one body, to drive the pumping part 20. The second shaft 36 is formed at the opposite position to the first shaft 32 and supported at the housing 10 proximate to the outlet port 12. The electric motor 31 between the first shaft 32 and the second shaft 36 generates a rotation force by electricity. Any actuator may be used in addition to the electric motor 31. The electric motor 31 comprises: a permanent magnet 34, and a rotor 33 positioned in a magnetic field region generated by the permanent magnet 34. Since the electric motor 31 is obvious to those skilled in the art to which the present invention pertains, no further description thereof will be presented. The first shaft 32 and the second shaft 36 are respectively formed to protrude, at predetermined lengths, from both sides of the electric motor 31. The first shaft 32 is installed through the guide partition 13 so that the electric motor 31 is secured in the housing 10. One end of the second shaft 36 is inserted into the housing 10 proximate to the outlet port 12, to secure the electric motor 31. Bushings 40 are respectively positioned about the outer circumferential surfaces of the first shaft 32 and the second shaft 36 contacting with the housing 10, to minimally reduce friction D when the first shaft 32 and the second shaft 36 rotate and to smoothly rotate the first shaft 32 and the second shaft 36. The bushings 40 are obvious to those skilled in the art to which the present invention pertains, no further description thereof will be presented. The bushings 40 are respectively positioned around the outer circumferential 5 surfaces of the first shaft 32 and the second shaft 36 but they are not fixed.

Therefore, when the first shaft 32 and the second shaft 36 rotate, the bushings 40 are spaced apart from the housing 10 at a predetermined distance and therefore no wearing between the bushings 40 and the housing 10 is caused. Accordingly, durability of the fuel pump 100 is improved to prolong the useful lifetime of the fuel pump 100. However, in reference to FIGS. 2 and 3, when the bushings 40 are spaced apart from the housing 10, the electric motor 31, first shaft 32 and second shaft 36 of the motor part 30 are shaken, not to be secured. To prevent this problem, another ball 35 is inserted into an end of the second shaft 36 (which is a part contacting with the housing 10 proximate to the outlet port 12). The ball 35 is not fixed, to minimize friction with the housing 10 when the second shaft 36 with the ball 35 rotates. The end of the second shaft 36 includes a connection opening 36a to receive the ball 35 being inserted. As the ball 36 is inserted into the end of the second shaft 36, the electric motor 31 and second shaft 36 of the motor part 30 are prevented from shaking, to reduce the wearing of the motor shafts and the housing 10. An insertion opening 15 to receive the ball 35 inserted into the end of the second shaft 36 is formed in the inner surface of the housing 10 proximate to the outlet port 12, to prevent the ball 35 from being separated. The ball 35 may be inserted to be attached to and detached from the end of the second shaft 36, it may be fixed with the second shaft 36 in one body or it may be attached to the end of the second shaft 36 in different ways. The ball 36 may be made by selectively using any one of silicon carbide (SiC), alumina (A1 2 0 3 ) and zirconia (ZrO 2 ), which are the same materials used for the first shaft 32 and the second shaft 36. 1A The case 50 is hollow to install the housing 10 inside. A high-temperature LPG fuel discharged through the outlet port 12 of the housing 10 through the pumping part 20 and the motor part 30 is cooled between the case 50 and the housing 10, to reduce heat load of the LPG fuel. A number of outlets 51 are formed at an end of the case 50, to discharge the uniformly cooled LPG fuel outwardly from the case 50. A partition 52 is formed in the case 50, to circulate the high-temperature LPG fuel so as to be cooled through a number of channels. The partition 50 is supported by the inner side of the case 50 and the outer side of the housing 10, to guide the LPG fuel. (Second Embodiment) As illustrated in FIGS. 4 and 5, a housing 10 comprises: an inlet port 11 and an outlet port 12. The inlet port 11 is formed around an end of a side of the housing 10, to admit LPG fuel. The outlet port 12 is formed around an end of another side of the housing 10, to discharge the LPG fuel. The inlet port 11 of the housing 10 is connected to a fuel tank (not shown), and the outlet port 12 of the housing 10 is connected to a fuel injector (not shown) of an engine. In reference to FIGS. 4 and 6, a pumping unit 20 comprises: a carrier 21, a roller 24, a first plate 22 and a second plate 23. The carrier 21 is operatively connected to a first shaft 32 of a motor part 30 and is rotated by the first shaft 32, to transfer the LPG fuel admitted through the inlet port 11 into the housing 10. The roller 24 is formed to surround an outer circumferential surface of the carrier 21. The first plate 22 is positioned at one side of the carrier 21 and includes a flow opening 25. The flow opening 25 is formed in a fan shape at an inner side of the first plate 22, so that the LPG fuel drawn by the carrier flows in a lateral direction through the flow opening 25. The second plate 23 is positioned at the other side of the carrier 21 and includes a transfer opening 26 and a through-aperture 27. The transfer opening 26 is formed to be curved so that the LPG fuel flowing through the flow opening 25 of the first plate 22 by the carrier 21 is transferred in a vertical direction. The through-aperture 27 is formed in the center of the second plate 23 to receive the first shaft 32 so as to be connected to the carrier 21. The constitution of the other elements of an external LPG fuel pump according to the second embodiment is the same as that according to the first embodiment described above. (Third embodiment) As illustrated in FIG. 7, a ball 35 is connected, in one body, to a middle part of a housing 10 proximate to an outlet port 12 and be in contact with an end of a second shaft 36. The second shaft 36 smoothly rotates by the ball 35. The ball is attached to the housing 10 in one body when the housing 10 is manufactured. The constitution of the other elements of an external LPG fuel pump according to the third embodiment is the same as that according to the first embodiment described above. (Forth embodiment) As illustrated in FIG. 10, a number of grooves 3 are formed in a circumferential direction on the top of a round protrusion part 2. Each of the grooves 3 is formed outwardly from the through-aperture 1 towards an outer circumferential edge of the round protrusion part, at a predetermined space (from the outer circumferential edge of the round protrusion part 2). The grooves 3 are formed in a spiral shape taken as a whole. 16 The groove 3 is formed to be progressively wider, in its width, outwardly, from an inner circumferential edge of the round protrusion part 2 (i.e., from the through-aperture 1) towards an outer circumferential edge of the round protrusion part 2, so that a carrier 21 is pushed to the opposite side on which the grooves 3 are formed by flowing the fuels into the grooves 3 and increasing pressure inside the grooves 3. The pressure of the fuel most increases in the most outer side of the groove 3. The constitution of the other elements of an external LPG fuel pump according to the fourth embodiment is the same as that according to the first embodiment described above. (Fifth embodiment) As illustrated in FIG. 11, a number of grooves 3 are formed in the circumferential direction on the top of a round protrusion part 2. Each of the grooves 3 is formed to be extended from an outer circumferential edge of the round protrusion part 2 to a through-aperture 1. The groove 3 is formed to be progressively narrower, in its width, towards the through-aperture 1, so that a carrier 21 is pushed to the opposite side on which the grooves 3 are formed by flowing the fuels into the grooves 3 and increasing pressure inside the grooves 3. The grooves 3 are formed in a herringbone shape taken as a whole. The herringbone shape is formed in the shape of "C". The constitution of the other elements of an external LPG fuel pump according to the fifth embodiment is the same as that according to the first embodiment described above. (Sixth Embodiment) As illustrated in FIG. 12, a number of grooves 3 are formed in a circumferential direction on the top of a round protrusion part 2. The grooves 3 are 17 formed in a multi-stage on the top of the round protrusion part 2. In other words, each of the grooves 3 is formed independently (at a predetermined space from an outer circumferential edge of the round protrusion part 2 and at a predetermined space from an inner circumferential edge of the round protrusion part 2, i.e., a through-aperture 1). This type of the grove parts 3 is called a step-pocket. The groove 3 is formed in a planar fan-shape. The constitution of the other elements of an external LPG fuel pump according to the fifth embodiment is the same as that according to the first embodiment described above. As described above, in the external inline LPG fuel pump according to the present invention, the bushings are positioned around the first and second shafts of the motor secured inside the housing, the one ball is completely connected to the end of the first shaft, in one body, to prevent the motor from shaking by the bushings, and the other ball is inserted into the end of the second shaft to secure the motor, thereby preventing durability deterioration caused by the wearing of the bushing, the pumping part and the inside of a housing even though the LPG fuel flows into the fuel pump during the motor is driven, to prolong the useful lifetime of the fuel pump and to reduce costs of repair and replacement involved with the fuel pump. Furthermore, in the external inline LPG fuel pump according to the present ) invention, the case is formed to install the housing inside and the partition is disposed inside the case, thereby cooling the high-temperature LPG fuel discharged through the outlet port of the housing, to reduce heat load and to improve the durability of the device receiving the LPG fuel from the fuel pump. Furthermore, in the external inline LPG fuel pump according to the present invention, the LPG fuel flows in the lateral direction and is inline transferred by the 18 carrier, thereby improving suction of the LPG fuel through the inlet port, to increase the efficiency of flow in the inlet port. Furthermore, in the external inline LPG fuel pump according to the present invention, the carrier is structured to include: the through-aperture formed in the center of the carrier so as to be connected to the driving shaft of the motor, the round protrusion part formed at the surface around the through-aperture, and the grooves in various shapes formed in the circumferential direction of the round protrusion part around the through-aperture, so that the LPG fuel flows into the fuel pump through the grooves, thereby preventing the carrier from being pushed to one side and therefore from coming into contact with first plate by the pressure of the LPG fuel flowing into the fuel pump and maintaining equal pressure at both sides, to prevent noise and damage caused by friction upon rotation. While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims.

Claims

1. An external inline LPG fuel pump to compress pump LPG fuel, comprising: a housing (10) having an inlet port (11) formed at one side of the housing (10) and an outlet port (12) formed at the other side of the housing (10), to respectively admit and discharge the LPG fuel; a pumping part (20) positioned in the housing (10) proximate to the inlet port (11), to pump the LPG fuel into the housing (10); a motor part (30) positioned inside the housing (10) and including a first shaft (32), a second shaft (36), an electric motor (31) and bushings (40), wherein the first shaft (32) is operatively connected to the pumping part (20) and an end of the first shaft (32) is formed with a ball in one body, to drive the pumping part (20), the second shaft (36) is formed at the opposite side to the first shaft (32) and supported at the side of the housing (10) proximate to the outlet port (12), the electric motor (31) is between the first shaft (32) and the second shaft (36), to generate a rotation force by electricity, and the bushings (40) each receive the first shaft (32) and the second shaft (36) being in contact with the housing (10), allowing the first shaft (32) and the second shaft (36) to rotate while the electric motor (31) is secured in the housing (10); and a case (50) surrounding the housing (10) including: a number of outlets (51) and a partition (52), wherein the outlets (51) cools the high-temperature LPG fuel discharged through the outlet port (12) of the housing (10) through the pumping part gn (20) and the motor part (30) and discharges the LPG fuel outwardly by reducing heat load.

2. The external inline LPG fuel pump of claim 1, wherein the pumping part (20) comprises: a carrier (21) connected to the first shaft (32) of the motor part (30) and rotated by the first shaft (32), to transfer the LPG fuel admitted through the inlet port (11) into the housing (10); a roller (24) formed to surround an outer circumferential surface of the carrier (21); a first plate (22) positioned at one side of the carrier (21) and including a flow opening (25) and a recess, wherein the flow opening (25) is formed in a fan-shape at an inner side of the first plate (22), so that the LPG fuel pumped by the carrier (21) flows in a lateral direction, and the recess is formed around the center of the first plate (22) coming into contact with the end of the first shaft (32) to prevent the first shaft (32) from separating to the right or left; and a second plate (23) positioned at the other side of the carrier (21) and including a transfer opening (26) and a through-aperture (27), wherein the transfer opening (26) is formed to be curved so that the LPG fuel flowing through the flow opening (25) of the first plate (22) by the carrier (21) is transferred in a vertical direction, and the through-aperture (27) is formed around the center so that the first shaft (32) passes through the through-aperture (27) to be connected to the carrier (21). 91

3. The external inline LPG fuel pump of claim 1, wherein an inner surface of the housing (10) proximate to the outlet port (12) includes an insertion opening (15) to receive a ball (35) inserted into an end of the second shaft (36), to prevent the ball (35) from separating from the end of the second shaft (36).

4. The external inline LPG fuel pump of claim 2, wherein the carrier (21) comprises: a through-aperture (1) formed around the center of the carrier (21), so that the carrier (21) is connected to the first shaft (32) of the motor part (30) through the through-aperture (1); a round protrusion part (2) formed at one side of the carrier (21) around the through-aperture (1); and a number of grooves (3) formed in a circumferential direction of the round protrusion part (2) around the though-aperture (1) so that equal pressure is applied to both sides, to prevent noise and damage caused by friction generated when the carrier (21) is pushed to one side by pressure of the fuel and comes into contact with first plate.

5. The external inline LPG fuel pump of claim 4, wherein each of the grooves (3) is formed inwardly from an outer circumferential edge of the round protrusion part (2) towards an inner circumferential edge of the round protrusion part (2), at a predetermined space from the inner circumferential edge of the round protrusion part (2), i.e., from the through-aperture (1), a width of the groove (3) becomes progressively narrower towards the inner circumferential edge of the round protrusion part (2), and the grooves (3) are formed in a spiral shape taken as a whole, so that the carrier (21) is pushed to the opposite side on which the grooves (3 )are formed by flowing the fuel into the grooves (3) and increasing pressure.

6. The external inline LPG fuel pump of claim 4, wherein each of the grooves (3) is formed outwardly from an inner circumferential edge of the round protrusion part (2), i.e. from the through-aperture, towards an outer circumferential edge of the round protrusion part (2), at a predetermined space from the outer circumferential edge of the round protrusion part (2), a width of the groove (3) becomes progressively wider towards the outer circumferential edge of the round protrusion part (2), and the grooves (3) are formed in a spiral shape taken as a whole, so that the carrier (21) is pushed to the opposite side on which the grooves (3 )are formed by flowing the fuel into the grooves (3) and increasing pressure.

7. The external inline LPG fuel pump of claim 4, wherein each of the grooves (3) is formed in a herringbone shape to be progressively narrower, in its width, towards an inner circumference edge of the round protrusion part (2), i.e., towards the through-aperture (1), so that the carrier (21) is pushed to the opposite side on which the grooves (3 ) are formed by flowing the fuel into the grooves (3) and increasing pressure.

8. The external inline LPG fuel pump of claim 4, wherein each of the grooves (3) is formed in a fan shape around the round protrusion part (2), so that the carrier (21) is pushed to the opposite side on which the grooves (3 ) are formed by flowing the fuel into the grooves (3) and increasing pressure.

9. The external inline LPG fuel pump of claim 1, wherein the ball (35) being in contact with the end of the second shaft (36) of the motor part (3) is connected to the housing (10) in one body in the middle of the inner surface of the housing (10) proximate to the outlet port (12), so that the second shaft (36) smoothly rotates.