Patent Application
20050011559
The invention relates generally to fuel systems for internal combustion engines, and more specifically to fuel pump modules that supply fuel to an internal combustion engine.
The use of fuel pump modules to pump fuel from fuel tanks is well known in the automotive industry. A typical fuel pump module may include, for example, a fuel reservoir, a fuel pump within the fuel reservoir, a fuel level sensor, one or more filters positioned upstream of the pump inlet, an in-line fuel filter positioned downstream of the pump outlet, and a pressure regulator. The fuel pump module typically rests on the bottom of the fuel tank and pumps fuel from the tank until the tank is substantially empty.
During operation of the fuel pump, the reservoir is continually being filled to ensure that a steady supply of fuel is available to the fuel pump at all times during operation of the pump. Normally, fuel is drawn into the reservoir from the fuel tank by the fuel pump. In the case that the fuel level in the fuel tank is low, or vehicle maneuvering causes the fuel to slosh inside the fuel tank such that the fuel pump inlet cannot draw fuel from the bottom of the tank, the fuel pump is able to draw fuel from within the reservoir. This allows for substantially uninterrupted operation of the fuel pump, in that the fuel pump is substantially prevented from “running dry” and causing unwanted cycling of the fuel pressure to the engine.
Conventional fuel pump modules typically utilize a valve assembly, sometimes referred to as a discriminator valve, that is designed, in part, to prevent the fuel accumulated in the reservoir from draining back into the fuel tank when the fuel pump is not operating. A conventional fuel pump module, having a conventional discriminator valve, is shown and described in more detail below.
Prior art discriminator valves may not properly seal the reservoir as intended, thus allowing fuel accumulated in the reservoir to leak past the valve assembly and drain back to the fuel tank. With this occurrence, the fuel pump may operate without an initial supply of fuel at start-up, thus potentially causing the pump to overheat, or potentially causing the fuel pump inlet to become uncovered such that the fuel pump has to “run dry” in the beginning moments of operation before fuel once again submerges the fuel pump inlet.
The invention provides an improved discriminator valve assembly that increases the retention of fuel in the reservoir. More specifically, the invention provides a fuel pump module including a reservoir configured to hold a supply of fuel. The reservoir includes a fuel passageway and defines a first seat on a first side of the fuel passageway and a second seat on a second side of the fuel passageway. The fuel pump module also includes a seal configured to be seated on the first and second seats to substantially seal the fuel passageway. Further, the fuel pump module includes a weight biasing the seal toward the first and second seats by contacting the seal only at a location between the first and second seats.
In one construction of the invention, the first and second seats are substantially annular, the seal is a substantially flat, annular disk, and the weight is substantially annular. In another construction of the invention, the weight includes a substantially convex surface at least partially in contact with the seal.
The invention also provides a fuel pump module having a weight that is configured to provide a gap between a lower surface of the weight and an upper surface of the seal. Fuel enters the gap and helps bias the seal toward the first and second seats. In one construction, the gap includes a first gap located adjacent the first seat and a second gap located adjacent the second seat.
Further, the invention provides a method for maintaining fuel within a fuel pump module. The method includes providing a reservoir having a fuel passageway and defining a first seat on a first side of the fuel passageway and a second seat on a second side of the fuel passageway, and biasing a seal toward the first and second seats to substantially seal the fuel passageway even when the first and second seats are not properly aligned. In one construction, the method further includes deflecting the seal in an area between the first and second seats to ensure contact between the seal and the first seat, and the seal and the second seat.
The invention also provides another method for maintaining fuel within a fuel pump module. The method includes providing a gap between a lower surface of a weight and an upper surface of the seal. In one construction, the method further includes allowing fuel to enter the gap to bias the seal toward the first and second seats. In another construction, providing the gap includes providing a first gap adjacent the first seat and providing a second gap adjacent the second seat.
Other features of the invention will become apparent to those skilled in the art upon review of the following detailed description, claims, and drawings.
Before any features of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of other constructions and of being practiced or being carried out in various ways. Also, it is understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including” and “comprising” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items.
The fuel pump module 10 can be inserted into a fuel tank 14 having a top wall 18, a bottom wall 22, and four side walls 26 (only two are shown). The top wall 18 includes an opening 30 through which the fuel pump module 10 is inserted into the tank 14. The opening 30 is preferably circular, but can also be various other shapes.
The fuel pump module 10 includes a reservoir 34 sized to fit through the opening 30. The reservoir 34 is substantially cylindrical and has an outer wall 38 that defines an interior portion 42 for housing fuel and other fuel pump module components, as is commonly understood. The outer wall 38 has respective upper and lower ends 46, 50. The reservoir 34 is open on the upper end 46 and includes a reservoir inlet 54 on the lower end 50. The reservoir 34 can be made by injection molding or any other suitable plastic forming technique.
Further included in the fuel pump module 10 is a fuel pump 58 that communicates with the reservoir inlet 54 and the interior portion 42 to pump fuel. The fuel pump 58 includes an inlet end 60 having a fuel inlet 62 that selectively receives fuel from either the tank 14 or the interior portion 42 of the reservoir 34, and a fuel outlet 66 where fuel exits the fuel pump 58. As shown in
A lower filter plate 78 filters fuel just before it is received by the fuel inlet 62 of the fuel pump 58. In the illustrated construction, the lower filter plate 78 is formed as a liquid-permeable membrane. However, the lower filter plate 78 can be of any other known configuration. The fuel pump module 10 may also include a fuel level sensor assembly (not shown) coupled to the reservoir 34. The fuel level sensor assembly provides a measure of the amount of fuel present in the tank 14, as is commonly understood. It should be noted, however, that the use of a fuel level sensing device or any particular type of fuel level sensing device is not critical to the present invention.
The fuel pump module 10 further includes a flange 82 supported above the upper end 46 of the reservoir 34 by support members 86. The flange 82 is the same shape, preferably circular, as the opening 30 in the top wall 18 of the tank 14 so that the flange 82 closes and seals the opening 30 when the fuel pump module 10 is fully inserted. The flange 82 includes an electrical connector (not shown) for providing electrical power to the fuel pump 58. The electrical connector also provides for communication between the engine control unit (not shown), the fuel pump 58, and the fuel level sensor assembly. The flange 82 further includes an outlet port 90 that is fluidly connected with the fuel outlet 66 of the fuel pump 58 by a conduit 94. The outlet port 90 allows fuel to exit the fuel tank 14 and enter the external portion of the fuel system. The flange 82 also includes an inlet port 98 that allows unused fuel to be returned to the fuel tank 14 by, for example, a conventional fuel return line (not shown). As shown in
The connecting portion 74 of the upper filter plate 70 includes a lower tapered end 102 extending below the fuel inlet 62 of the fuel pump 58. The lower tapered end 102 of the connecting portion 74 is positioned partially within a valve seat member 106 supported by the reservoir 34. As shown in
The fuel pump 58 is coupled to the reservoir 34 such that the fuel pump 58 can receive fuel from the fuel tank 14 via multiple fuel passageways 130 formed in the valve seat member 106. In the illustrated construction (see
With reference to
Referring to
During operation of a vehicle utilizing the prior art discriminator valve assembly 170, when there is a sufficient level of fuel in the fuel tank 14, the fuel pump 58 draws fuel from the fuel tank 14 through the reservoir inlet 54. In this situation, the ingress of fuel into the fuel inlet 62 overcomes the downward bias of the flat washer 158 and lifts and unseats the seal 150 from the inner and outer seats 134, 138. The upward movement of the flat washer 158 and seal 150 is limited by the lower tapered end 102 of the connecting portion 74. Fuel is therefore allowed to enter the reservoir 34 via the reservoir inlet 54, pass through the lower filter plate 78, through the fuel passageways 130, through the apertures 162, 166 in the seal 150 and the washer 158, and into the fuel inlet 62 of the fuel pump 58.
Also, during operation of the vehicle, the reservoir 34 is continually being filled by return fuel entering via the inlet port 98. Alternatively, for returnless fuel systems, the reservoir 34 may be continually filled by a separate jet pump assembly (not shown). As previously stated, while the fuel pump 58 is drawing fuel from the fuel tank 14, the flat washer 158 is maintained against the lower tapered end 102 of the connecting portion 74. As a result, the substantially annular opening 118 between the upstanding wall 126 of the valve seat member 106 and the lower tapered end 102 is substantially blocked by the washer 158 and the seal 150 such that fuel may accumulate in the reservoir 34 and even spill over the upper end 46 of the reservoir 34. Since the opening 118 is substantially blocked, little or no fuel is drawn from the interior portion 42 of the reservoir 34 into the fuel inlet 62 of the fuel pump 58.
When there is an insufficient amount of fuel in the fuel tank 14 or the fuel is not available at the reservoir inlet 54 due to vehicle maneuvering, the fuel pump 58 draws fuel from the interior portion 42 of the reservoir 34. This occurs when the ingress of fuel through the fuel passageways 130 is interrupted, causing the weight of the flat washer 158 to bias the seal 150 against the inner and outer seats 134, 138, thereby blocking the fuel passageways 130. At the same time, the opening 118 between the upstanding wall 126 of the valve seat member 106 and the lower tapered end 102 is uncovered by the downwardly moving washer 158, thereby allowing fuel from the interior portion 42 of the reservoir 34 to flow through the opening 118, into the valve seat member 106, and into the fuel inlet 62 of the fuel pump 58.
During periods between operation of the vehicle, when the fuel pump 58 is not active, the washer 158 biases the seal 150 against the seats 134, 138 to block the fuel passageways 130 to substantially maintain the level of fuel accumulated in the reservoir 34. However, if the seal 150 does not seat properly against the inner seat 134 and the outer seat 138, the fuel accumulated in the reservoir 34 can leak back into the fuel tank 14 through the fuel passageways 130. During periods of low fuel levels in the tank 14 and/or when the vehicle is parked on a slope so that fuel in the tank 14 is not readily available to the reservoir inlet 54, the fuel pump 58 can loose its prime of fuel. As a result, starting the engine may be problematic.
As shown in
The present invention provides an improved fuel pump module having many of the same components associated with the prior art fuel pump module 10 (e.g., the reservoir 34, the pump 58, the flange 82, etc.), with like components given like reference numerals. However, the improved fuel pump module of the present invention includes an improved discriminator valve assembly 178 that reduces or eliminates the leakage paths 174 that may occur using prior art discriminator valve assemblies 170 like those shown in
With reference to
The weight 182 is configured to contact the seal 150 only at a location between the inner and outer seats 134, 138. With this concentration of the weight 182 on the seal 150 at a location between the seats 134, 138, the resilient seal 150 is deflected, thereby conforming the seal 150 to any height irregularities between the inner and outer seats 134, 138. Sealing of the fuel passageways 130, even when there are height irregularities between the inner and outer seats 134, 138, is improved. It is important to note that the deflection of the seal 150 may vary from the deflection illustrated in
In the illustrated construction of
The weight 182 is also configured to provide at least one gap between the lower convex surface 186 of the weight 182 and an upper surface 206 of the seal 150. As best illustrated in
The size and configuration of the gaps 210, 214 are determined in part by the shape of the weight 182, and more specifically, by a convex slope angle θ defined by the lower convex surface 186 relative to a substantially horizontal plane containing the contact interface between the substantially flat apex portion 198 and the upper surface 206 of the seal 150. As illustrated in
In addition to ensuring that contact between the weight 182 and the seal 150 occurs only at a location between the first and second seats 134, 138, the outer and inner gaps 210, 214 further facilitate proper sealing of the fuel passageways 130 by allowing fuel to move freely into the gaps 210, 214 when the fuel pump 58 is not active. As fuel is allowed to flow into the gaps 210, 214, the fuel pressure acts directly on portions of the seal 150 between and adjacent the inner and outer seats 134, 138. The added fuel pressure in the gaps 210, 214 helps to bias the seal 150 toward the seats 134, 138 and deflect the seal 150 so that it conforms with any height irregularities or waviness between the inner and outer seats 134, 138. In the illustrated construction, the portion of the outer gap 210 located directly adjacent (above, as viewed in
Generally, as indicated by an average trend line 226 of the six sample reservoirs 34, the sample reservoirs 34 utilizing the weight 182 lost some of their fuel shortly after the beginning of the test, after which time the rate of fuel loss decreased substantially throughout the remainder of the 24-hour test period. On average, the initial height of fuel in the six sample reservoirs 34 was 97.2 mm. After the 24-hour test period, on average, the retained height of fuel in the six sample reservoirs 34 was 33.2 mm. This corresponds to a fuel height loss of 64 mm, or a loss of 66% of the initial level of fuel in the reservoirs. On average, the reservoirs 34 utilizing the weight 182 retained about 16.6 times the fuel retained by the reservoirs 34 utilizing the conventional flat washers 158.
Various features of the invention are set forth in the following claims.
