Pumps – Three or more cylinders arranged in parallel – radial – or... – Condition responsive fluid control
Patent
1995-07-26
1998-09-01
Freay, Charles G.
Pumps
Three or more cylinders arranged in parallel, radial, or...
Condition responsive fluid control
F04B 4900
Patent
active
058001310
DESCRIPTION:
BRIEF SUMMARY
CROSS REFERENCE TO RELATED APPLICATIONS
This application is a national phase of PCT/DE 94/00087 filed 27 Jan. 1994 and based, in turn, on German national application P 43 02 610.9 of 30 Jan. 1993 under the International Convention.
FIELD OF THE INVENTION
The invention relates to a process for the regulation of the pumping capacity of lubricant pumps in which the pumping capacity is regulated by the pressure at the pump outlet or at a consumer site, such that when the pressure increases the pumping capacity is effectively reduced. The present invention relates also to a lubricant pump which may be regulated and comprises a regulating device by which the pumping capacity is effectively reduced in order to limit the lubricant flow.
BACKGROUND OF THE INVENTION
A process and a pump, specifically a vane pump, with pressure regulation, are known from German Offenlegungsschrift No. 40 11 679.
The pressure at the discharge side of a pump of this type can be caused to act on a regulating piston on which a compression spring acts from the opposite side directly or indirectly. The piston acts on the displaceable ring of the vane pump and influences thereby its eccentricity and the lubricant flow. The pump and the regulating device are so designed that when the pressure at the discharge side of the pump increases, the piston displaces the displaceable ring in the direction of smaller eccentricity so that by the reduction of the lubricant flow the pressure at the discharge side of the pump is reduced. By the use of suitable compression springs and geometries of the regulating device the regulating characteristics of such a pump may be varied within wide limits.
The application of the present invention is, however, not limited to vane pumps. The invention may be used particularly for all pumps which can be regulated, particularly pumps using only a so-called loss control, i.e. in which, when a predetermined pressure is exceeded, excessive lubricant is directed through a bypass around consumer sites while only the lubricant flow (effective lubricant flow) pumped through the system is reduced but not the total quantity pumped. Naturally, rather than using such systems it is preferable to use controllable pumps whose pumping capacity or lubricant flow may be directly influenced and not only their effective lubricant flow.
The term "effective lubricant flow" is intended to mean that volume of he lubricant which is pumped under pressure per unit time through the consumer sites, the corresponding supply and discharge lines and possibly auxiliary, upstream units, such as oil filters. Oil, which is pumped, for instance through bypasses, from and back to a pump reservoir is not considered to be part of the effective lubricant flow. Also draining off oil through bypasses reduces the pressure at the discharge side of the pump and in the whole system so that no energy saving can be achieved. A significant reduction of energy is achieved only when the volume pumped by the pump is from the outset adapted to the demand as is the case with controllable vane pumps or constant-displacement pumps with multi-stage control systems.
Such lubricant pumps are used particularly to supply lubricant to lubrication points in internal combustion engines, particularly for motor vehicles.
The demand for lubricant or the minimum demand of an internal combustion engine depends however on a number of different factors. A significant factor is the working temperature of the engine and/or of the relevant lubrication points and also of the lubricant. When it is cold, oil, used generally as a lubricant, has a high viscosity and may be forced only with difficulties through narrow spaces at the lubrication points. At the same time also the demand on lubricant of a cold internal combustion engine is not very high because the parts moving with respect to each other have in a cold state generally a smaller clearance from each other and the viscosity of the oil is high so that less oil may be forced through.
In view of this, the effective pumping capacity o
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Power Input and Storage, U.S. Publication "Machine Design" Jun. 1990, pp. 554-586.
Technical Publication No. 1, Dea and Texaco Verkauf GmbH, "Schmierung", 1970.
Lehmann Uwe
Stich Bodo
Wilhelm Maik
Dubno Herbert
Freay Charles G.
Mercedes-Benz Aktiengesellschaft
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