Internal-combustion engines – Charge forming device – With fuel pump
Reexamination Certificate
2000-06-13
2001-06-05
Moulis, Thomas N. (Department: 3747)
Internal-combustion engines
Charge forming device
With fuel pump
C123S514000, C417S062000, C417S251000
Reexamination Certificate
active
06240904
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
Not applicable.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not applicable.
BACKGROUND OF THE INVENTION
This invention relates to multi-stage fuel pumps such as are used in marine engine systems, and more particularly, to a two-stage fuel pump which is used in a stand alone configuration in such systems.
In co-pending, co-assigned U.S. patent application Ser. No. 551,586/09 filed Apr. 18, 2000, there is described a two-stage marine fuel pump used in an integrated fuel system. As described therein, the pump includes first and second pumping elements commonly mounted on a motor driven shaft. Fuel drawn into an inlet of the pump is pumped through the first element (comprising a first pump stage). Fuel expelled from the first stage is pumped into a reservoir from which it is drawn into an inlet of the second pump stage. Outlet fuel from the second stage is pumped to a fuel rail for delivery to a marine engine. All of the pump components are installed in a common housing and the pump has only a single fuel inlet and a single fuel outlet.
It has now been found that the two-stage pump is also useful in a variety of other fuel system configurations. In these applications, it is now advantageous to separate the first stage from the second stage so that even though the common mounting construction of components in the pump is the same as described in the co-pending application, routing of fuel to and from the pump stages allows greater flexibility in use of the pump.
BRIEF SUMMARY OF THE INVENTION
Among the several objects of the present invention is a two-stage marine fuel pump in which fuel is separately supplied to each pump stage rather than the fuel flowing from the first stage flowing directly to an inlet of the second stage.
Another object of the invention is such a fuel pump in which all of the pump components are commonly installed in a single housing, in which the pumping elements comprising the two pump stages are commonly mounted on a single drive shaft, but in which each stage has a separate inlet and a separate outlet.
A further object of the invention is such a fuel pump in which the pump stages can be connected in series, in parallel, or in series-parallel depending upon a particular fuel system application. For example, the pump stages are connected to fuel filters, external fuel pressure regulators, fuel coolers, etc. in implementing different fuel system configurations.
In accordance with the invention, generally stated, a stand alone two-stage marine fuel pump is usable in a variety of fuel system configurations. The pump includes pumping elements for each pump stage which are commonly mounted on a motor driven drive shaft. The first pump stage pumps fuel at a first pressure, and the second stage pumps fuel at a second and higher pressure. There is a separate fuel inlet and fuel outlet for each stage. This allows low pressure fuel from the outlet of the first pump stage to be supplied to one portion of the fuel system, and higher pressure fuel from the outlet of the second stage to be supplied elsewhere in the system. Accordingly, each pump stage is stand alone. In one fuel system configuration, the outlet of the first pump stage is routed to the inlet of the second pump stage. However, in other fuel system configurations, there is one path for routing fuel to the fuel inlet of the first pump stage and from the outlet thereof, and a separate path for routing fuel to the inlet of the second pump stage and from the outlet thereof. In these configurations fuel pumped from the first stage of the pump is delivered other than to the fuel inlet of the second pump stage, and fuel supplied to the inlet of the second pump stage is delivered other than from the fuel outlet of the first pump stage. Other objects and features will be in part apparent and in part pointed out hereinafter.
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Boutwell Rodney
Meyer Paul M.
Stephens Bruce
Ulm Ralph
Moulis Thomas N.
Polster Lieder Woodruff & Lucchesi L.C.
UIS, Inc.
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