Rotary expansible chamber devices – With changeable working chamber magnitude – Spring or fluid biased movable member
Patent
1996-04-23
1997-11-25
Vrablik, John J.
Rotary expansible chamber devices
With changeable working chamber magnitude
Spring or fluid biased movable member
418 27, 418 30, F04C 2344, F04C 1504
Patent
active
056904797
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a multi-stage regulator for pumps, in particular for lubricant pumps, with a regulating piston to which pressure can be applied from pressure derived from the output side of the pump, and with increasing pressure can be displaced counter to the force of a flexible restoring element.
Such a regulator is, for example, known from regulatable vane-cell pumps. Generally in this case a piston with a circular cross-section is guided in a cylinder and pressure is applied to it by means of a branch conduit from the output side of the pump. A counter-compression spring opposes resistance to the movement of the piston in the cylinder resulting from the action of the pump pressure. A drive pin for the adjustment ring of the vane-cell pump is located, for example, between the piston and the spring. By displacement or pivoting of the adjustment ring relative to the rotor of the vane-cell pump, the eccentricity of the vane-cell pump is altered and thereby also the displaced volume of the individual cells of the pump as well as the hydraulic pumping capacity as a whole. The relative arrangement of piston, spring, rotor, adjustment ring and drive pin is in addition selected so that with rising pressure, as a result of the piston moving forward increasingly in opposition to the force of the compression spring, the adjustment ring is pressed over the drive pin, in the sense of less eccentricity relative to the rotor, so that the pumping capacity reduces and the output pressure sinks, or else is kept constant. The pump parameters which can be pre-determined, that is to say in concrete terms the geometry and size of the rotor and adjustment ring, the maximum and minimum eccentricity thereof determined by the maximum regulating distance of the piston-spring-drive pin system, and the spring characteristics, determine the properties of the regulator, that is to say above all the maximum pressure which can occur at the pump output. The speed the load connected to the output side of the pump, which represents a pressure sink with a more or less adjustable, and generally temperature dependent, flow resistance.
Such pumps are often found in internal combustion engines, which are generally used over a wide range of revolution speeds and at variable operating temperatures. In this case the pump shaft is normally directly connected to the crankshaft of the engine, and thus rotates at the same revolution speed as the engine, or at least at a revolution speed proportional thereto.
If the oil pressure produced by such a pump is plotted (at a given temperature) against the engine revolution speed, normally a more or less linear progression is found, up to a pre-determinable maximum value of, for example 5 bar, wherein above the revolution speed at which this value is reached, the pressure is kept constant with the aid of the regulator.
The oil pressure necessary for an internal combustion engine is also dependent on the revolution speed, above all because the engine has pivot bearings and rotating parts and the lubricant has in part to be conveyed radially inwards from outside, counter to the effect of centrifugal force, to rotating parts in order to guarantee sufficient lubrication of such areas. As a result there is generally a non-linear increase in the minimum necessary oil pressure with increasing revolution speed.
The development of minimum oil pressure for a typical combustion engine is shown as curve a in FIG. 1, wherein at the same time the development of the oil pressure of a lubricating oil pump with pressure control, coupled to an engine, is also shown, as curve b.
The hydraulic capacity of a pump results from the product of the volume flow produced and the pressure difference between the output and input of the pump. Regulatable lubricant pumps such as, for example, vane-cell pumps, have the property of using pressure as the regulation parameter, as the pressure acts indirectly or directly on the adjusting member which can alter the eccentricity of the piston ring, so that the amount of adjustme
REFERENCES:
patent: 2975717 (1961-03-01), Rynders et al.
patent: 3415058 (1968-12-01), Underwood et al.
patent: 4325215 (1982-04-01), Yamamoto
Lehmann Uwe
Stich Bodo
Wilhelm Maik
Mercedes-Benz Aktiengesellschaft
Vrablik John J.
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