DOUBLE VANE PUMP

Abstract: A rotary vane pump in which two sets of vanes (3, 3') are each slidably mounted on a rotor shaft (1), each set of vanes being axially spaced, the vanes of the first set being preferably set at 45<o> to those of the second set, each set of vanes forming a pumping section which feeds into a common pump outlet (72), preferably the inlet (71) is between the sets of vanes and feeds axially into pump chambers (54a-d) formed between the vanes and the rotor.

Description: TITLE: DOUBLE VANE PUMP 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. 5 These pumps comprise a rotor 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 10 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 . The 0 rotor of the known pumps are radially ported so that as the rotor revolves in the stator a portion of th 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 5 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 posi¬ tion onthe 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° ' 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. OMPI 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° to the vane s des. Hitherto this angle has been about 75°. 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 will now be described by way of example with reference to the accompanying drawings in which: Figure " 1 is a transverse vertical cross-section of a first embodiment of the invention being a universal rotary vane pump, Figure 2 is an axial horizontal cross section of the first embodiment taken along line A-A of Fig. 1, Figure 3 is an axial vertical cross section of a second embodiment of the invention being an inboard fixed flow pump section being taken along line A-A of Figure 4, Figure 4 is a transverse vertical cross section of the second embodiment being on the left a section along line B-B and on the right a section along line C-C of Fig 3, Figure 5 is an axial vertical cross section of a third embodiment of the invention being an outboard fixed flow pump the section being similar to that of Fig. 3, Figure 6 is a vertical cross section of a hand control valve for varying the output of the pumps shown in Figs. 3 to 5, Figure 7 is a vertical cross section of a hydraulic control arrangement replacing the hand control valve of Fig. 6. In Figures 1 and 2 may be seen a rotary shaft 1 provided with two transverse slots 2 at right angles to each other and forming a first set of slots, and two transverse slots 2' at right angles to each other forming a second set of slots. The second set.of slots is axially aligned at 45 to the first set. Each slot 2, 2' has a pair of vanes 3, 3' mounted therein. Each vane has parallel sides 33 ; a perpendicular inner end face 34 and an angled or chamfered outer end face 35 which is angled at 80 to the vane sides at θ. That is to say is angled at 10 to the inner end face. The vanes freely slide in slots 2, 2'. The vanes may be both coupled in similar way to those shown in British Patent No. 1,013,801 or else one diametral pair may be coupled as shown at 3a_ in Fig. 1 and the other diametral pair may be uncoupled but in abutting relationship as shown at 3b_ in Fig. 1. The outer end faces 35 abut on inner planer surfaces 4 of a rotor 5 the outer cylindrical surface 51 of which is carried rotatably by an inner corresponding surface 61 of a cage 6 which is either fixed in a stator 7 as shown in Figs. 3 and 5 or else can be adjustable to vary the distance and thus the eccentricity between the rotor axis 52 and shaft axis 12. This adjusting may bo either by a manual arrangement as shown in Fig. 6 or by a hydraulic arrangement as shown in Fig. 7. A similar axially spaced rotor 5' to rotor 5 is provided in stator 7 for the second set of vanes 3' . Between each inner planar surface 4 of each rotor 5, 5' is curved surface 53. Chambers 54a_, b_, are formed between the vanes and rotor 1 and a fourth chamber 54d. is scarcely formed. An inlet 71 and outlet 72 in stator 7 are provided which connect with the pump chambers 54a. - cl. The inlet and outlet diverge in a centre member 8 to provide two inlet ducts 81 and 81' and two outlet duct 82 and 82' which stream the inlet and outlet liquids axially into and out of the pump chambers. This eliminates the need for ports in the outer periphery of the rotors which reduces or eliminates the acceleration and deacceleration of the fluid in the suction and delivery lines caused by the rotor ports, thereby together with the split flow the pump may run faster and more quietly than known pumps. Also by eliminating the rotor ports this has the effect of increasing the area of the cage 6 supporting the rotors which enables the pump to operate at higher discharge pressures. Figures 3 to 5 show in more detail two embodiments of the pump of the invention. The indexing of parts similar to those of Figures 1 and 2 is the same as in those figures. The inboard pump shown in Figure has roller bearings 90 which are lubricated by the medi being pumped. A seal 91 either mechanical or soft pack seals between the shaft 1 and stator 7. The outboard pump shown in Figure 5 is designed to handle low lubric liquids or liquids not compatible with roller "bearings ; in this pump shaft 1 is supported in roller bearings 93 are external of the liquid being pumped and are grease lubricated. The bearings 93 are in turn supported in brackets 94. The stator 7 is sealed to shaft 1 by mean of mechanical or soft packing seals 95. Brackets 94 al form heating or cooling chambers 96. In Figures 3 to 5 a cover plate 100 is provid on the stator 7 when the pumps are used as fixed flow pumps. The cover plate has a centre stud 101 which locks the cage 6 to the stator. When it is desired to convert the pumps to variable flow pumps, cover plate 100 and stud 101 are removed and either the hand control generally shown at 103 in Figure 6 or the hydraulic actuator generally shown at 105 in Figure 7 are bolted to the stator. In the hand control 103 a handwheel 107 has a threaded portion 109 which cooperates with a threaded sleeve 110 to move a pin 112 up or down. Pin 112 is connected to cage 6 so that the cage eccentricity can be varied. In the hydraulic actuator 105 a- piston 116 is secured to a pin 118 which is connected to cage 6 so that piston movement causes the cage eccentricity to be varied Piston 116 works in cylinder 118 the upper part of which above the piston 116 is connected via line 12θ to accumulator chamber 124 in accumulator 122. The space 126 above piston 116, line 12 and chamber 124 are filled with hydraulic oil. Weight is applied to weight containe 128 in the form of steel pellets 130. The weight of the container 128 and pellets 130 pressurises the oil in line 120, the container 1 , 28 sliding up and down ram 129. Pump pressure is fed to space 132 under the piston. A slight change in pump discharge pressure causes piston 116 to move which in turn moves cage 6 thus adjusting the pump output until the system balances again.

Claims: AMENDED CLAIMS [received by the International Bureau on 19 March 1984 (19.03.84); original claims 1 to 19 replaced by amended claims 1 to 11] 1. A rotary van pump comprising a pair of rotors and a rotor shaft, two sets of vanes only, slidably mounted to the shaft at separate longitudinal positions on the shaft, the rotors and stator surrounding each vane set, the rotors having flats on their inner surfaces on which the outer ends of the vanes engage, a common pump inlet and a common pump outlet between the vane sets, with axial feeds from the inlet to rotary pump chambers formed either side of the inlet between the vanes, rotor, rotor shaft and stator. 2. A pump as claimed in claim 1 wherein the inlet and outlet diverge in a centre member to provide two inlet ducts and two outlet ducts to stream the inlet and outlet fluids axially into and out of the pump chambers. 3. A pump as claimed in claim 1 wherein the vanes of the first set of vanes are set at 45° to those of the second set. 4. A pump as claimed in any one of claims 1 to 3 wherein the outer ends of the vanes terminate in a flat surface angled at about 80° to the vane sides. 5. A pump as claimed in any one of claims 1 to 4 wherein each set of vanes has its separate rotor. 6. A pump as claimed in any one of claims 1 to 5 wherein the rotors are mounted in cages which are adjustable radially from the pump axis so as to vary the distance OiV-Pl between the or each rotor axis and the shaft axis. 7. A pump as claimed in claim 6 wherein the radial adjustment is by means of a piston or the like. 8. A pump as claimed in claim 6 wherein the radial adjustment is by means of a hand-operable control cooperating with a threaded member to move the cage so that the cage eccentricity may be varied. 9. A pump as claimed in claim 7 wherein the piston or the like is mounted in a cylinder connected to an accumulator chamber in an accumulator by a conduit filled with a liquid. 10. A pump as claimed in claim 9 wherein the liquid acts on one side of the piston or the like whilst the pump discharge is connected to the other side of the piston or the like, and wherein the accumulator pressure is adjustable to vary the pressure acting on said one side of the piston or the like. 11. A pump as claimed in claim 10 wherein the accumulator comprises a hollow fixed shaft or ram the interior of which is connected to the cylinder, and wherein the accumulator chamber surrounds a part of the shaft or ram, the chamber being formed in apart of a container the container containing weighting means, preferably a number of weights, the weight of which can be adjusted to bias the pressure acting on said one side of the piston or like.

Inventors: KAIN ALEXANDER STANLEY, KAIN, ALEXANDER, STANLEY
Applicants: PLENTY LTD, PLENTY LIMITED
Application year: 1983
Main classification: F04C11
IPC codes: F04C2, F04C11, F04C14