Patent Application
20160245284
The present invention relates to a fluid pump which pumps fluid; more particularly to a fuel pump which pumps fuel; even more particularly fuel pump including a diverter plate which minimizes pressure pulsation transmission and prevents foreign matter present in the fuel from depositing in a pumping arrangement of the fuel pump.
Fluid pumps, and more particularly fuel pumps for pumping fuel, for example, from a fuel tank of a motor vehicle to an internal combustion engine of the motor vehicle, are known. A typical fuel pump includes a housing within which generally includes a pump section, a motor section, and an outlet section. The pump section includes an inlet plate, an outlet plate, and a pumping arrangement between the inlet plate and the outlet plate. The pumping arrangement is rotated by an electric motor located in the motor section, thereby causing fuel to be drawn into the housing through an inlet of the inlet plate and through an outlet passage of the outlet plate. The fuel then passes past the electric motor and exits the housing through an outlet of the outlet section. The fuel pump may be an impeller type fuel pump where the pumping arrangement is an impeller as shown in U.S. Pat. No. 8,556,568 to Fisher, the disclosure of which is incorporated herein by reference in its entirety or the fuel pump may be a gerotor-type fuel where the pumping arrangement is an inner gear rotor surrounded by an outer gear rotor as shown in U.S. Pat. No. 6,769,889 to Raney et al., the disclosure of which is incorporated herein by reference in its entirety. Alternatively, the fuel pump may be a vane-type fuel pump, a gear-type fuel pump, or a roller vane-type fuel pump.
Fuel pumps as described above are typically oriented with the pumping section oriented down, i.e. in the direction of gravity, while the outlet section is oriented up, i.e. away from gravity. Consequently, when the fuel pump is not operating, particulate matter that may be present in the fuel that has already exited the outlet passage of the outlet plate may settle downward, passing through the outlet passage of the outlet plate and depositing in the pumping arrangement. Foreign matter that settles in the pumping arrangement may lead to binding, fracturing, and increased wear of the pumping arrangement when the fuel pump is subsequently operated. Furthermore, the physics associated with the pumping arrangement moving the fuel from the inlet plate to the outlet plate may generate pressure pulsations which may propagate through the structure of the fuel pump, hoses, and fuel surrounding the fuel pump which may produce undesirable noise.
What is needed is a fuel pump which minimizes or eliminates one or more of the shortcomings as set forth above.
Briefly described, a fluid pump includes a housing; an outlet which discharges fluid from the housing; an inlet plate disposed within the housing, the inlet plate having an inlet which introduces fluid to the housing; an outlet plate disposed within the housing, the outlet plate having an outlet plate outlet passage; an electric motor disposed within the housing between the outlet plate and the outlet, the electric motor having a shaft which rotates about an axis; a pumping arrangement rotationally coupled to the shaft such that rotation of the pumping arrangement by the shaft causes fluid to be pumped from the inlet to the outlet plate outlet passage and through the outlet; a diverter plate disposed between the outlet plate outlet passage and the electric motor, the diverter plate having a diverter passage which provides fluid communication from the outlet plate outlet passage, past the electric motor, to the outlet, the diverter plate also having an imperforate wall which is axially aligned with the outlet plate outlet passage such that the imperforate wall laterally directs fluid from the outlet passage to the diverter passage. The imperforate wall of the diverter plate prevents foreign matter that may be present in the fuel from passing through the outlet plate outlet passage and depositing in the pumping arrangement when the fluid pump is not operating. The diverter plate also mitigates pressure pulsations generated by the pumping arrangement, thereby minimizing noise generated by the fluid pump.
This invention will be further described with reference to the accompanying drawings in which:
Reference will first be made to
Motor section 14 includes an electric motor 20 which is disposed within housing 18. Electric motor 20 includes a shaft 22 extending therefrom into pump section 12. Shaft 22 rotates about a first axis 24 when an electric current is applied to electric motor 20. Electric motors and their operation are well known, consequently, electric motor 20 will not be discussed further herein. Electric motor 20 may be configured as shown in United State Patent Application Publication No. US 2014/0314591 A1 to Herrera et al., the disclosure of which is incorporated herein by reference in its entirety.
With continued reference to
Inner gear rotor 28 includes a plurality of external teeth 44 on the outer perimeter thereof which engage complementary internal tooth recesses 46 of outer gear rotor 30, thereby defining a plurality of variable volume pumping chambers 48 between inner gear rotor 28 and outer gear rotor 30. It should be noted that only representative external teeth 44, internal tooth recesses 46 and pumping chambers 48 have been labeled in the drawings. As shown, inner gear rotor 28 has eight external teeth 44 while outer gear rotor 30 has nine internal tooth recesses 46, however, it should be understood that inner gear rotor 28 may have any number n external teeth 44 while outer gear rotor 30 has n+1 internal tooth recesses 46. Inlet 40 of inlet plate 26 is aligned with a portion of gear rotor bore 36 within which the geometry between external teeth 44 and internal tooth recesses 46 create pumping chambers 48 of relative large size while outlet plate outlet passage 42 of outlet plate 32 is aligned with a portion of gear rotor bore 36 within which the geometry between external teeth 44 and internal tooth recesses 46 create pumping chambers 48 of relatively small size. Inner gear rotor 28 is rotationally coupled to shaft 22, consequently, when electric motor 20 is rotated by application of an electric current, inner gear rotor 28 rotates about first axis 24. By virtue of external teeth 44 engaging internal tooth recesses 46, rotation of inner gear rotor 28 causes outer gear rotor 30 to rotate about second axis 38. In this way, the volume of pumping chambers 48 decreases as each pumping chamber 48 rotates from being in communication with inlet 40 to being in communication with outlet plate outlet passage 42, thereby causing fuel to be pressurized and pumped from inlet 40 to outlet plate outlet passage 42.
Diverter plate 34 segregates the portion of housing 18 which houses pump section 12 from the portion of housing 18 which houses electric motor 20, consequently, diverter plate 34 is disposed between outlet plate outlet passage 42 and electric motor 20. Diverter plate 34 includes a diverter passage 50 which provides fluid communication from outlet plate outlet passage 42 and past electric motor 20 to outlet 19. As shown, diverter passage 50 may be comprised of a plurality of individual diverter passages 50 which extend axially through diverter plate 34. Diverter plate 34 also includes an imperforate wall 52 which is axially aligned with outlet plate outlet passage 42. Consequently, imperforate wall 52 laterally directs fuel from outlet plate outlet passage 42 to diverter passage 50.
Diverter plate 34 may also include a plurality of diverter channels 54 which extend laterally across the side of diverter plate 34 which faces toward outlet plate 32 such that each diverter channel 54 provides fluid communication from outlet plate outlet passage 42 to at least one diverter passage 50. Diverter channels 54 may be shaped to be divergent toward diverter passages 50, and as shown, may be dovetail shaped in cross-section. As shown best in
Diverter plate 34 may also include a contamination trap 56 which is illustrated as a recess in the face of diverter plate 34 that faces toward electric motor 20. Contamination trap 56 is arcuate in shape and has an arc length that is less than 360°. In operation, rotation of electric motor 20 causes the fuel within motor section 14 to swirl around first axis 24 as the fuel flows toward outlet 19. Contamination trap 56 produces a low pressure area which may allow foreign matter present in the fuel to settle and deposit. While contamination trap 56 has been illustrated as being arcuate in shape, it should now be understood that contamination trap 56 may take many forms which may be, by way of non-limiting example, a pattern of square, diamond, or triangles; a series of recessed ribs, or a cross-hatch pattern on the surface of diverter plate 34 that faces toward electric motor 20.
A diverter central aperture 58 extends axially through diverter plate 34 such that diverter central aperture 58 is centered about first axis 24, consequently allowing shaft 22 to extend coaxially through diverter central aperture 58. Diverter central aperture 58 is sealed, for example by engaging outlet plate 32, thereby preventing fuel from passing through diverter central aperture 58. Diverter plate 34 is also sealed on the outer perimeter thereof, for example by engaging a flux carrier of electric motor 20 as shown or alternatively by engaging the inner perimeter of housing 18. In this way substantially all fuel that exits outlet plate outlet passage 42 is laterally directed to and passes through diverter passages 50.
In practice, fuel pump 10 is oriented with pump section 12 facing down, i.e. toward gravity, while outlet 19 is oriented facing up, i.e. away from gravity. Consequently, when fuel pump 10 is not in operation, particulate matter that may be present in motor section 14 tends to settle down toward diverter plate 34. However, since diverter passages 50 are not axially aligned with outlet plate outlet passage 42 of outlet plate 32, the foreign matter that has already passed through diverter passages 50 will not have access to outlet plate outlet passage 42, and consequently, imperforate wall 52 shields outlet plate outlet passage 42 from the foreign matter, thereby preventing the foreign matter from depositing in inner gear rotor 28 and outer gear rotor 30. Furthermore, contamination trap 56 creates an area of stagnation which promotes deposition of foreign matter within contamination trap 56.
In operation, the pumping arrangement comprising inner gear rotor 28 and outer gear rotor 30 generate pressure pulsations. However, diverter plate 34 acts to mitigate the pressure pulsations, thereby minimizing noise generated by fuel pump 10. More specifically, the geometry of diverter channels 54 and diverter passages 50 can be tailored to optimize the mitigation of pressure pulsations, without being bound by theory, by breaking up the pressure pulsations. If mitigating pressure pulsations generated by the pumping arrangement is not an objective, diverter channels 54 may be omitted and diverter passages 50 may be increased in size and decreased in number. Similarly, diverter channels 54 may be omitted depending on the magnitude of pressure pulsation mitigation that is desired since diverter passages 50 may be able to be tailored to provide sufficient mitigation of pressure pulsations alone.
As described herein, diverter plate 34 has been illustrated as a standalone component, however, it should now be understood that diverter plate 34 could alternatively be integrated with other elements of fuel pump 10. By way of non-limiting example only, diverter plate 34 may be integrally formed with a magnet holder of electric motor 20 where the magnet holder is configured to hold permanent magnets that are used to cause rotation of electric motor 20.
As described herein, the pumping arrangement has been illustrated as inner gear rotor 28 and outer gear rotor 30. However, it should now be understood that the pumping arrangement may take other forms which may include, by way of non-limiting example only, an impeller, roller vanes, gears, or vanes.
While this invention has been described in terms of preferred embodiments thereof, it is not intended to be so limited, but rather only to the extent set forth in the claims that follow.
