Pumps – Processes
Reexamination Certificate
1998-05-18
2001-02-06
Freay, Charles G. (Department: 3746)
Pumps
Processes
C417S270000, C417S286000, C417S287000, C417S427000
Reexamination Certificate
active
06183207
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a pump.
2. Background Information
Pumps are used to create fluid flow and increase a fluid pressure within an hydraulic system. For example, some internal combustion engines contain a pump that increases the pressure of hydraulic fluid which is used to hydraulically actuate intensified fuel injectors of the engine. Such engine pumps may contain one or more pistons that are reciprocated within a pump chamber by a wobble plate. Each revolution of the wobble plate causes the piston to draw in fluid through an inlet port and then pressurize and push the fluid through an outlet port of the pump.
The wobble plate is mechanically coupled to the rotational output of the engine. The speed of the pump is controlled by the speed of the engine. Consequently, the output of the pump increases with a corresponding increase in the engine speed. It may be desirable to increase or decrease the output of the pump without varying the speed of the engine. It would therefore be desirable to provide a pump which can vary the pump output to a number of different levels for a given input speed of the pump.
SUMMARY OF THE INVENTION
One embodiment of the present invention is a pump which can selectively operate in a number of different modes, wherein each mode corresponds to a different output of the pump. The pump may have a plurality of pump chambers located within a pump housing. The pump chambers may be coupled to an inlet port and an outlet port. Each pump chamber may have a pumping device which draws in fluid from the inlet port during an intake stroke and pushes fluid through the outlet port during a power stroke. The pump may also have a plurality of valve assemblies which control the output of the pump. The valve assemblies may be operated in a number of different modes. Each mode creates a different pump output.
REFERENCES:
patent: 4326839 (1982-04-01), Fry et al.
patent: 5050233 (1991-09-01), Hitosugi et al.
patent: 5456581 (1995-10-01), Jokela et al.
patent: 5700136 (1997-12-01), Sturman
patent: WO 91/04414 A1 (1991-04-01), None
patent: WO 97/43548 A1 (1997-11-01), None
patent: WO 98/03788 A1 (1998-01-01), None
Blakely , Sokoloff, Taylor & Zafman LLP
Freay Charles G.
Sturman Industries, Inc.
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