Lubrication – Systems – With measuring or metering value system
Patent
1986-07-07
1987-12-08
Smith, Leonard E.
Lubrication
Systems
With measuring or metering value system
184 29, G01F 1104, F16N 2700, F16K 2116
Patent
active
047113219
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a device for metering liquid media, particularly lubricants, comprising a plunger: body acting between an inlet and an outlet in a chamber being circular in section, said body having on the one hand a suitably conical closing part with the purpose of blocking the outlet when the plunger body is moved to a forward end position, and on the other hand having a piston or piston-shaped part with a diameter that is at least somewhat smaller than the diameter of the chamber, so that a gap is formed between the outside of the piston and the inside of a housing confining the chamber, said medium being able to pass through said gap in order to charge the space between the piston and the outlet when the plunger body, suitably by means of a spring, is being returned to a backward end or starting position, a sealing ring, placed in the area of the periphery of the piston, being arranged to cooperate with a conically narrowing surface in such a way that said sealing ring is brought closer to said conical surface when the plunger body is moved in the direction towards the outlet in order to seal or close said gap and in that way render a backflow of the medium past the piston impossible, and on the other hand being distanced from the conical surface and allowing free passage for the medium past the piston, when the plunger body is moved in the direction towards the inlet.
When in the following discussion, in connection with the invention, liquid media are discussed, this is not intended to mean only such thinly fluid liquids as oils and the like but also such media that are semi-liquid or viscous, as for instance fats or thixotropic liquids.
BACKGROUND OF THE INVENTION
For the lubrication of vehicles and/or machines of different kinds, so called single pipeline systems are often used that work with pressure sequences in an arrangement of conduits that lead from a pressure producer or feeding pump to those separate metering devices or elements, which are included in the system to a number that agrees with the number of lubrication points. The most simple metering element consists of a restriction in the form of a calibrated orifice. At a given pressure difference a metered amount is dispensed by this kind of element, which amount is a function of the area of the orifice, the viscosity of the lubricating medium and the duration of the pressure. This kind of metering element is however generally considered to be too inaccurate.
In order to obtain good accuracy it is required that the metering element meters a given volume of medium independently of variations in the pressure, of the viscosity of the medium and of the tolerances in the metering element.
Metering devices of the above described kind are disclosed in the U.S. Pat. Nos. 1,897,609 and 2,000,925. These designs do however not function satisfactorily. The metering element does not have any stable sealing function of the "sluicing cone" of the metering piston.
In the design according to U.S. Pat. No. 1,897,609, the piston element in question floats freely in its associated chamber without any hydrostatically defined position in relation to the cone in question. This means that the piston will oscillate in every intermediate position in relation to the cone. In the end positions other conditions arise and mechanical stops and hydrodynamic forces influence the function. The essential factor, from the functional point of view, is however that the metering piston is not "tight" in its path between the end positions, which results in that an indefinably larger amount of lubricant than intended being discharged.
In the design according to U.S. Pat. No. 2,000,925 an attempt has been made to remove this drawback by introducing a spring that is intended to forcibly close the cone against the piston. In this case as well, however it is impossible to make this solution stable. In order to meet the two functional conditions at the discharge and at the return, certain conditions have to be met. The requirements thus are that the cone has to be closed
REFERENCES:
patent: 1652764 (1927-12-01), Cowles
patent: 1767490 (1930-06-01), Sweet
patent: 1881842 (1932-10-01), Moore
patent: 1897609 (1933-02-01), Cowles
patent: 2000925 (1935-05-01), Cowles
patent: 2532269 (1950-11-01), Davis
patent: 3119463 (1964-01-01), Jackson
patent: 3559765 (1971-02-01), Smith
patent: 3985205 (1976-10-01), Hedlund et al.
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