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US 4,053,902 AGranted
Fluid pump for a writing device
AssigneeSiemens Aktiengesellschaft
InventorsBengt Skafvenstedt, Sture Ahlgren, Eberhard Tschuertz
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AssigneeSiemens Aktiengesellschaft
InventorsBengt Skafvenstedt, Sture Ahlgren, Eberhard Tschuertz
Estimating the term…
A pump mechanism for delivering ink or the like writing fluid from a reservoir to a point of utilization such as a writing device. The mechanism includes a piston slidable in a cylinder for drawing ink into the cylinder during a suction stroke and discharging the ink during a pumping stroke. The cylinder is formed by a cylinder wall which includes a frusto-conical portion tapered inwardly in a direction away from the piston. The piston comprises a single plastic member having a forward end portion which faces and cooperates with the tapered portion of the cylinder wall and which has an outside diameter which is greater than the smallest diameter of the tapered cylinder wall portion, whereby the forward end portion of the piston engages the tapered cylinder wall portion as the piston moves forward during a pumping stroke. The front or forward wall of the piston is recessed to enable the forward end portion of the piston to deform and slidingly engage the tapered cylinder wall in sealing engagement as the piston moves forward in a pumping stroke. The forward end portion moves out of engagement with the tapered cylinder wall portion as the piston moves backward during a suction stroke.
A pump mechanism for delivering ink or the like writing fluid from a reservoir to a writing device comprising a pump housing having an internal cylinder wall forming a cylinder, a piston disposed within said cylinder and slidable forward in a pumping stroke and backward in a suction stroke, and drive means for moving said piston through said pumping and suction strokes, said cylinder wall comprising a frusto-conical portion tapered inwardly in a direction away from said piston, and said piston comprising a plastic member having a forward end portion which cooperates with said tapered portion of said cylinder wall and which has an outside diameter which is greater than the smallest diameter of said tapered cylinder wall portion to slidingly engage the same in sealing relation as said piston moves forward during a pumping stroke, and to move out of engagement with the same as the piston moves backward in a suction stroke, said forward end portion of said piston having a forward facing recess formed therein permitting radially inward deformation of said forward end portion of said piston upon engagement thereof with said tapered cylinder wall portion.
Dependencies are inferred from the claim text.
Drawings are temporarily unavailable. Open the PDF at USPTO
The means being cams, eccentrics or pin-and-slot mechanisms: the means being pin-and-slot mechanisms
Ink supply systems ; Circuit parts therefor: ink pumps, ink valves
Piston machines or pumps characterised by having positively-driven valving: in which the valving is performed by pistons and cylinders coacting to…
The means being cams, eccentrics or pin-and-slot mechanisms: the means being cams
Term ended 11 Oct 1994 (estimated)
USPTO file history isn’t available for this patent, so only indexed dates are shown.
This invention relates generally to fluid pumps and more particularly to a pump for delivering ink or the like writing fluid from a reservoir to a writing device. The pump of the present invention comprises a mechanism including a housing, a cylinder formed in the housing, a piston slidable within the cylinder and piston drive means for moving the piston forward and backward within the cylinder to provide a pumping stroke and a suction stroke.
Most known ink pumping mechanisms of this general description comprise a metal spring-loaded piston actuated by an eccentrically mounted wheel, and further include one or more spring loaded valves. Generally, the previously known constructions are complicated in design and have a relatively short useful life, due to a decrease in pumping effect, which in turn is proportional to the reduction in the effect of the spring of the spring-loaded piston.
An object of the present invention is to overcome these deficiencies and to provide a pump for ink or the like writing fluids which is relatively simple in design, inexpensive in manufacture and capable of having a long, useful life.
The drawing is a vertical sectional view of a pump mechanism incorporating the principles of the present invention.
Referring to the drawing, there is disclosed a fluid pump mechanism, indicated generally at reference numeral 1, for pumping ink or the like writing fluid from an ink reservoir or container 2 to a writing device indicated at reference numeral 3. The writing device 3 may be one of many well known types and may correspond, for example, to the writing device disclosed in U.S. Pat. No. 2,566,443.
The pump mechanism 1 comprises a pump housing 4 in which is formed a cylinder 5. A piston 6 is carried for slidable movement within the cylinder 5. The piston 6 is made of a one-piece plastic member and is driven forward during a pumping stroke to deliver ink from the cylinder 5 to the writing device 3, and is moved backward in a suction stroke to draw ink from the reservoir 2 into the cylinder 5.
The means for driving the plastic piston 6 forward and backward comprises, in the embodiment illustrated, a toothed wheel or gear 11, which is mounted for rotation on a shaft 10 journalled in a gear housing 9. A cam follower groove 12 is formed in the gear 11 and disposed therewithin is a rotatable cam follower 14 mounted for rotation on a shaft 13 and connected to a piston rod 7 which, in turn, is fixedly connected to the piston 6. The gear 11 is rotated by means of a pinion 15 which in turn is driven by a suitable driving mechanism such as, for example, an electric motor indicated at reference numeral 16.