BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be better understood from the following detailed description of the preferred embodiments thereof, taken in conjunction with the accompanying drawings, wherein like reference numerals refer to like parts, in which:
FIG. 1 is a sectional view of portion of a fuel delivery system in accordance with an embodiment of the present invention.
FIG. 2 is an exploded view of a pump unit of the system of FIG. 1.
FIG. 3 is plan view of a pump cover of the pump unit of FIG. 2.
DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENT
With reference to FIG. 1, a sectional view of a portion of a fuel delivery system is shown, generally indicated at 10, in accordance with an embodiment of the invention. The system 10 includes a pump unit, generally indicted at 12. The pump unit includes a pump housing 14, a pump cover 16, and an impeller 18 there-between. The impeller 18 is coupled to a shaft 20 of a motor (not shown) for rotation therewith. The shaft passes through an opening 22 in the pump housing 14.
With reference to FIGS. 2 and 3, the pump cover 16 includes a body 23 having inlets 24a, 24b and a jet outlet 26, 26′. As best shown in FIGS. 1 and 3, the pump cover 16 also includes a first inner channel 28a and second outer channel 30a in the body 23. The outer channel 30 is thus located radially outward of the inner channel 28a. The pump housing 14 includes a first inner channel 28b and second outer channel 30b (see FIG. 2). Thus, when the pump unit 12 is assembled, inner channels 28a and 28b cooperate to form a first channel 32 and outer channels 30a and 30b cooperate to form a second channel 34 (see FIG. 1).
As shown in FIG. 2, the impeller 18 includes first set of vanes 36 and a second set of vanes 38. The vanes 36 are located radially inward of and coplanar with vanes 38. When the pump housing 14 is assembled with the pump cover 16 with the impeller 18 encased therein, inner vanes 36 are aligned radially with channel 32 and the outer vanes 38 are aligned radially with channel 34.
With reference to FIG. 1, fuel is contained in a reservoir 37 that is disposed near a bottom of a fuel tank (not shown). When a motor rotates the shaft 20, the impeller 18 rotates to draw fuel (shown by arrows F) through the inlets 24a and 24b. Fuel that enters inlet 24b is pumped by inner vanes 36 of the impeller 18 through channel 32, to the jet exit 26, 26′ and through a jet nozzle 38 of a jet pump, generally indicated at 41. The nozzle 38 is associated with a venturi tube 40 of the jet pump such that suction occurs to draw fuel F′ from the tank into the reservoir 37 to replenish the reservoir. Fuel F that enters inlet 24b is pumped by outer vanes 38 of the impeller 18 through channel 34. Fuel F″ is then pumped out of a fuel outlet 42 through pump housing 14 to supply fuel to the engine (not shown).
With this dual channel configuration, there are times when vapor is present in the channel 32 and thus there is a delay in jet pump activation. To address this delay, with reference to FIGS. 2 and 3, connecting structure is provided to fluidly connect the channels 32 and 34. More particularly, the connection structure is in the form of a connecting channel 44 (FIG. 3) that connects inner channel 28a with outer channel 30a of the pump cover 16 and a channel 44′ (FIG. 2) that connects inner channel 28b and outer channel 30b in the pump housing 14. The channels 44, 44′ allow fluid to flow from the respective outer channel to the respective inner channel with a controlled flow rate and a controlled set pressure to prime the inner channels 28a, 28b and thus improve the performance of the inner channels 28a, 28b by reducing the jet activation delay.
The channel 32 has a working pressure of about 1 Bar and the channel 34 builds to a system pressure of about 4 Bars. The location of the channel 44, 44′ should be at the place in the outer channels 30a, 30b where the outer channel is at approximately 1 Bar. Also, channel 44 is downstream of purge hole 46 (FIG. 3). This ensures that the pressure in the jet system is not exceeded and also ensures that any vapor in the outer channel 30a is purged before it reaches the channel 44.
The size and shape of the connecting channels 44, 44′ are selected to minimize jet activation delay without significantly decreasing the overall efficiency of the fuel pump unit, since the connecting channels 44, 44′ take fuel from the outer channels 30a, 30b decreasing flow to the engine. The size of the channels 44, 44′ is selected to introduce just enough fluid flow into the respective inner channel to minimize jet activation delay. In the embodiment, fluid flows through the connection channels 44, 44′ at approximately 10 L/h.
The embodiment shows connecting channels 44 and 44′ that ensure a consistent location of the channel connection with respect to a pressure build-up location and so as not to introduce potential noise harmonic orders. It can be appreciated that the connecting channel 44 can be provided without channel 44′ or channel 44′ can be provided without channel 44 depending on the application. The channels 44, 44′ are preferably machined, but can be provided in the die cast tool without requiring an additional machining operation. The channels 44, 44′ are located so as to not introduce additional turbulence in the fluid streams, for example, to ensure a smooth transition of fluid from the respective outer channel to the respective inner channel.
The foregoing preferred embodiments have been shown and described for the purposes of illustrating the structural and functional principles of the present invention, as well as illustrating the methods of employing the preferred embodiments and are subject to change without departing from such principles. Therefore, this invention includes all modifications encompassed within the spirit of the following claims.
Patent Application
20070251508
