Rotary expansible chamber devices – With changeable working chamber magnitude – Spring or fluid biased movable member
Patent
1984-05-15
1985-11-05
Vrablik, John J.
Rotary expansible chamber devices
With changeable working chamber magnitude
Spring or fluid biased movable member
418 31, 418173, 418212, F04C 1100, F04C 1504
Patent
active
045510792
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to rotary pumps of the sliding vane type.
Rotary pumps of the sliding vane type are well known and for example are shown in British Patent No. 834,925. These pumps comprise a rotory driven by a rotor shaft, the rotor shaft having four vanes slidingly mounted in slots in the shaft, the ends of the vanes being in bearing engagement with inwardly facing bearing surfaces provided on the rotor to form four pump chambers between the vanes and rotor. Rotation of the rotor shaft causes rotation of the rotor and fluid is conveyed by the rotating pump chambers from an inlet in the pump casing or stator to an outlet in the casing or stator. Such pumps may be variable in capacity by moving the axis of the rotor surrounded by a sliding cage relative the shaft and stator. The ends of the vanes where they bear on the rotor are often angled or chamfered relative to the tangent of the radial centre line of the vanes at an angle of about 15.degree.. The rotor of the known pumps are radially ported so that as the rotor revolves in the stator a portion of the stator which can be on the sliding cage interacts with the ports to open or close the chambers.
Such pumps produce a pulsating output, each pulse corresponding in frequency to the rate of travel of each vane and subsequent vane past the outlet. In order to reduce the pulse frequency it is possible to increase the number of vanes. Unfortunately this results in a large rotor diameter since the rotor must have provision for each blade to slide in it.
A rotary vane pump according to the present invention comprises a rotor shaft, a rotor, a set of vanes slidably mounted to the rotor shaft at one axially longitudinal position on the rotor shaft, and a second set of vanes slidably mounted to the rotor shaft at a second axially longitudinal position on the rotor shaft, a stator surrounding the rotor, the first set of vanes and rotor forming a first pumping section and the second set of vanes forming a second pumping section where each pumping section feeds into a common pump outlet.
Preferably there are four vanes in each set, those of the first set being set at 45.degree. to those of the second set. Preferably each set has its own rotor.
Advantages of the pump of the invention are that the outlet flow is smoother and therefore faster, the rotor can be also made smaller and thus a smaller pump may be provided for a given duty.
According to another aspect of the invention a rotary vane pump according to the present invention comprises a rotor and rotor shaft, at least one set of vanes slidably mounted to the shaft and a stator having a pump inlet with an axial feed from the inlet to rotary pump chambers formed between the vanes and the rotor.
Preferably a second set of vanes slidably mounted on the rotor shaft is provided, the second set being axially longitudinally spaced from the first set and wherein the feed from the inlet to the rotary pump chambers formed by each set of vanes is axial. The axial feed may be from the centre of the stator axially outwards.
Feeding the pump chambers axially eliminates the need for ports in the side of the rotor which in turn eliminates the acceleration and deacceleration of fluid in the inlet and outlet lines caused by the rotor ports. Thus removal of the need for ports combined with splitting the flow enables the pump to run faster and more quietly. Furthermore eliminating the rotor ports has the effect of increasing the area supporting the rotor which enables the pump to operate at higher discharge pressures.
Combining the increased output with an increased running speed enables the smaller pump to be offered for a given duty.
Preferably the vane ends terminate in a flat surface angled at about 80.degree. to the vane sides. Hitherto this angle has been about 75.degree.. The increase in angle that is the decrease in terminal slope enables the rotor bore to be increased and in turn the eccentricity between stator block or cage and rotor axes can be increased so as to further increase the pump output.
The invention
REFERENCES:
patent: 1607383 (1926-11-01), Aurand
patent: 1719134 (1929-07-01), Roessler
patent: 1780217 (1930-11-01), Wiltse
patent: 2720171 (1955-10-01), Harrington et al.
patent: 3065706 (1962-11-01), Shoosmith
Plenty Limited
Vrablik John J.
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