Pumps – Condition responsive control of drive transmission or pump... – Adjustable cam or linkage
Patent
1994-12-27
1997-04-08
Thorpe, Timothy
Pumps
Condition responsive control of drive transmission or pump...
Adjustable cam or linkage
418 31, 418 24, F04B 4900
Patent
active
056181655
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a pump comprising a pump housing and a shaft-driven rotor having at least two outwardly spring-biased elements which lie in contact with the wall of a chamber surrounding the rotor and which, during rotation of the rotor, transport a gas and fluid medium from a suction port to a pressure port in the pump housing.
BACKGROUND TO THE INVENTION
Pumps according to the above are used for example for producing lubrication oil pressure in combustion engines for vehicles. The oil is transported by pressure to various parts of the engine and is used for lubricating a large number of bearings and hydraulic engine components.
It is normally required of an oil pump that it should give the required pressure even at the idling speed of the engine. Thus at higher speeds an unnecessarily high oil pressure is produced, which has to be reduced in some way, e.g. via an overflow valve.
The pump is normally driven by a power take-off from the engine drive shaft and the overproduction of oil pressure therefore has an effect on both the fuel consumption and the usable power. A variable displacement pump should be able to reduce the power requirement especially at speeds above idling. Such pumps are known but present disadvantages since they are comparatively expensive and complicated.
OBJECT OF THE INVENTION
The main object of the invention is therefore to achieve a pump which can deliver direct flow with constant pressure at varying speeds and which pump does not present the above mentioned disadvantages.
SUMMARY OF THE INVENTION
In order to achieve this object the invention is characterized in that the chamber surrounding the rotor is arranged in a body which is displaceable inside the pump housing in such a way that the chamber is movable between two end positions, of which one end position presents a comparatively small eccentricity with respect to, the rotating shaft of the rotor and the other end position presents a comparatively large eccentricity with respect to said shaft and in that the pump is provided with means for positioning of the body in the pump housing. The relatively small eccentricity in the one end position may be a small non-zero value or may be zero, in which case the housing in concentric with the shaft. Due to the design of the pump according to the invention, it can be used either in order to give the correct flow with constant back pressure at varying speed, or to give a varying flow at a constant speed.
Preferred embodiments of the invention are defined in the dependent claims.
BRIEF DESCRIPTION OF THE DRAWINGS
An embodiment of the invention will now be described in more detail with reference to the accompanying drawings, in which
FIG. 1 shows a longitudinal section through a pump according to the invention,
FIG. 2 is a cross-section through the pump shown in FIG. 1,
FIG. 3 shows the pump according to FIG. 2 with the sliding block displaced, and
FIG. 4 is another longitudinal section through a second embodiment according to the invention.
DESCRIPTION OF PREFERRED EMBODIMENTS
The oil pump shown in the figures is driven by a shaft 10 of a pulley 11, which is connected with a power take-off of a combustion engine via a V-belt (not shown). The shaft 10 is supported in position in a pump housing 12 by means of bearings 13, 14 and is operated at a speed which is proportional to the speed of the combustion engine. The capacity of the pump is so adapted that it is able to maintain the necessary oil pressure even when the engine is driven at its lowest speed.
The pump housing 12 is provided with end walls 35, 36 a suction port 15 and a pressure port 16 arranged parallel to this. An oblong chamber 17 contains a displaceable sliding block 18, said sliding block being connected with a control rod 19 which extends out through the wall of the pump housing on one of the short sides of the housing via a passage sealed with a sealing ring 20.
The control rod 19 extends into a chamber 21 coaxial with the longitudinal direction of the rod, said cham
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Albertsson Gert
Larsson Erik
AB Volvo
Korytnyk Peter G.
Thorpe Timothy
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