US 6,651,545 B2Granted

Fluid translating device

AssigneeCaterpillar Inc.

InventorAndrew H. Nippert

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Abstract

It is desirable to deliver only the fluid that is used to do useful work and not waste energy. In the subject arrangement, selected ones of a plurality of pistons are held at their top dead center positions when delivery therefrom is not needed. This is accomplished by having a valving arrangement disposed between the associated pressure chambers and first and second inlet/outlet ports. The valving arrangement is movable from a neutral, flow blocking position to an operative flow passing position. At the flow blocking position, fluid flow into and out of the associated pressure chamber is blocked, thus the associated piston is maintained at the top dead center position. By holding selected ones of the pistons at the top dead center position, the effective volume of fluid being used is reduced and energy is saved due to the fact that the selected pistons are not moving any fluid.

Claims12

Dependent claims

A variable displacement fluid translating device, comprising:

a housing having first and second inlet/outlet ports and defining a reference axis therethrough
a rotating cam disposed in the housing along the reference axis and having a cam surface;
a plurality of piston bores defined in the housing about the reference axis and each bore of the plurality of piston bores having a bottom portion;
a plurality of pistons slideably disposed in the plurality of piston bores and selectively in mating contact with the cam surface of the rotating cam;
a plurality of pressure chambers defined in the housing between the respective one of the plurality of pistons and the bottom portion of the respective ones of the plurality of piston bores;
a valving arrangement connected between selected pressure chambers of the plurality of pressure chambers and the respective first and second inlet/outlet ports and being operative to selectively block fluid flow in and out of each pressure chamber to hold the respective piston at a predetermined position, each of the valving arrangements including first and second valving assemblies;
and
first and second electrically controlled actuators operatively connected to each of the first and second valving assemblies.

5 more elements

A method of controlling the relative position of respective ones of a plurality of pistons within a variable displacement fluid translating device, comprising the steps:

providing a housing having first and second inlet/outlet ports and a reference axis;
providing a rotating cam having a cam surface in the housing along the reference axis;
forming a plurality of piston bores in the housing about the reference axis;
providing a plurality of pistons in the plurality of piston bores that are slideably disposed in the respective piston bores and that are selectively in mating contact with the cam surface of the rotating cam;
establishing a plurality of pressure chambers between the respective one of the plurality of pistons and the respective ones of the plurality of piston bores;
and
providing first and second valving assemblies between one selected pressure chamber of the plurality of pressure chambers and the respective first and second inlet/outlet ports, the first and second valving assemblies being operative to selectively block the fluid flow in and out of the one pressure chamber to maintain the associated piston at a predetermined position.

4 more elements

Dependencies are inferred from the claim text.

Facts

Application: 10/021,869Filed 13 Dec 2001
Published: US 2003/0110935 A119 Jun 2003
Granted: 25 Nov 2003
Term ends: Not estimatedThe source records don’t support an estimate.

Classification4 codes

F04B 49/121
By varying the length of stroke of the working members: lost-motion device in the driving mechanism
F04B 1/063
Control: by using a valve in a system with several pumping chambers wherein the flow-path through the chambers can be changed, e.g. between series…
F04B 49/03
Stopping, starting, unloading or idling control: by means of valves
F04B
Positive-displacement machines for liquids