THIS INVENTION relates to an improved fluid motor or pump.

In one form the invention resides in a fluid motor or pump comprising a plurality of separate co-axial cylindrical chambers each chamber having a drive rotor mounted therein and being provided with inlets and outlets, each rotor having a plurality of spiral blades formed thereon, the blades on the respective rotor being arranged so that if the rotors were to be placed in end to end abutting rela¬ tionship the blades would be contiguous, the angle subten¬ ded by each blade being greater than 360/n where n is the number of the blades so that each blade overlaps the succeeding blade each drive rotor mating with a pair of diametrically opposed sealing rotors located in chambers positioned parallel to the cylindrical chambers said sealing rotors being provided with spiral recesses to re¬ ceive the spiral blades of the driving rotors in constant mesh.

The invention will be better understood by reference to the following description of several specific embodiments thereof as shown in the accompanying drawings wherein:-

Fig. 1 is a plan view of a drive rotor suitable for the present invention;

Fig. 2 is an elevation of two drive rotors in-end to end abutting relationship;

Fig. 3 is an elevation of the two drive rotors dis¬ placed axially with respect to each other; Fig. 4 is an isometric view of a unit having three sets of rotors, each set comprising one drive rotor and two diametrically opposed sealing rotors meshing with the drive rotor;

Fig. 5 is a plan view of one set of rotors located within cylindrical chambers showing an example of fluid movement within the inlet and outlet ports and chambers in relation to the direction of rotation of the respective rotors;

Fig. 6 is a partially sectional isometric diagramma¬ tic view of drive and seal rotors mounted within a housing showing an arrangement of ports; Fig. 7 is an isometric diagrammatic view of an arran¬ gement of housing segments indicating relative move¬ ment of fluid between various stages in a mul¬ ti-staged device; and

Figs. 8A - 8H shows various arrangements of rotor assemblies.

Referring to Figs. 1 to 3 of the drawings the rotors 13 and 14 shown have five spiral blades 5, 6, 7, 8, 9 the angle subtended by each blade over the total assembly of co-axial rotors being greater than 360/n where n is the number of blades. Thus in the embodiment shown each blade turns through an angle exceeding 72° from one end to the other. The amount that this angle exceeds 360/n is prefer¬ ably such that the overlap of one blade over the succeed¬ ing blade approximates the width of a blade.

It will be appreciated that this overlap still exists if the two rotors 13, 14 are replaced by 3 or more rotors of the same composite length.

Fig. 3 shows how the rotors may be axially displaced rela¬ tive to each other without affecting the overlap or align¬ ment of the blades.

Referring to Fig. 4, drive rotors 21, 22, 23 are mounted as a common output shaft 25 in such a way as to prevent rotational displacement of each relative to each other or to the shaft 25.

Seal rotors 15, 16, 17 are similarly mounted on common shaft 26 as are seal rotors 18, 19, 20 with respect to common shaft 24.

Bearings 27 - 32 locate the shafts in parallel axial arrangement.

It will be appreciated that by virtue of the overlap of the drive rotors, the seal rotors remain in constant mesh with the drive rotor without the need for timing gears or the like and further that any further overlap may exist without any deleterious affect on the meshing between the rotors.

Referring to Fig. 5, drive rotor 33 mounted on shaft 36 turns within cylindrical chamber formed by housing seg¬ ments 37, 38 seal rotors 34, 35 turn within cylindrical chambers formed by housing segments 138, 139 respectively. Spiral blades 44 - 48 on the rotor 33 mesh in constant mesh with spiral recesses 49 - 54 of the seal rotors 34 and 35. Fluid enters inlet ports 40, 41, passing through chambers 55, 56 and exiting through outlets 42, 43.

The construction of the unit is such that the volume of the chamber 55 defined by each pair of blades 44, 45 re¬ mains substantially constant. Thus the capacity of the unit as compared to a screw device is improved.

Fig. 6 shows one embodiment of the device comprising three sets of rotors as illustrated in Fig. 4. Housing segments 56, 57 and parts of top plate 58 and dividing plates 59, 60 are shown as removed in the drawing for the purpose of illustrating the manner in which the sets of rotors and their respective chambers are separated by the dividing plates 59, 60, the axial location of the dividing plates being such as to prevent the inlet ports communicating

directly with the respective outlet ports via the chamber encompassed by a pair of spiral blades.

Fig. 7 shows how rotor sets of different face widths may be used for the purpose of ulti staging. In this device three stages are used the fluid entering the first inlet is subsequently directed by a manifold, not shown, to the second and third inlets from each preceeding outlet.

It will be appreciated that the capacity and output of the device may be varied by varying the rotor widths as indi¬ cated in Figs. 8B and 8C, by adding rotors as indicated in Fig. 8D, by ganging sets of rotors as indicated in Fig. 8E, by multiple staging as indicated in Figs. 8F and 8G or by varying -the rotor diameters as indicated in Fig. 8H.

A unit consisting of a pair of chambers each having an in¬ let and an outlet and separated by a dividing plate and each chamber accommodating a drive rotor and two sealing rotors was operated as an air motor with each chamber having its own air supply was subjected to a number of tests using the following equipment and instrumentation:-

EQUIPMENT

1. Air Supply

engine - driven mobile air compressor

- two air supply hoses to the motor under test, each fitted with an automatic oiler.

2. Instrumentation

Fischer and Porter Flowrator # 10A3565AFB11A fitted with # 448C414D01 tube and ^' # 303J133T60

float, rated at 677 cubic feet per minute at 21°C and 93 lbf/in ² .

pressure regulating valves fitted to the inlet and outlet of the flowrator fitted with pressure gauges.

commercial pressure gauge used to measure motor inlet pressure.

Go Power dynamometer, model DA 500, serial num¬ ber RD2076, and digital readout system, serial number P1050.

PROCEDURE

the first and second test runs were carried out using the flowrator outlet pressure regulator to control the motor inlet pressure.

subsequent runs were made with this pressure regulator removed from the circuit and the motor inlet pressure controlled using a ball valve in conjunction with the pressure gauge reading pressure at the motor inlet.

dynamometer load and air supply were adjusted to achieve selected speed and inlet pressure condi¬ tions. When conditions were stable the speed, torque and flowrator readings were recorded.

flowrator temperature and inlet pressure were also recorded.

Output power and air consumption over a range of operating speeds were calculated from the re¬ sults obtained and a set out in the following tables:-

TABLE I

Derived Results First Run Single-stage Motor

Speed r/min Corrected Torque Power Motor Inlet

Nm H..P. lbf/ln ³

750 81.0 8.5 85

750 83.1 8.7 88

770 86.3 9.3 90

770 87.4 9.4 95

960 79.9 10.8 84

1010 74.5 10.6 80

1020 75.6 10.8 83

1070 72.4 10.9 80

1150 72.4 11.7 •78

1300 66.0 12.0 75

1620 57.5 13.1 68

1910 48.9 13.1 60

2140 45.7 13.7 55

2400 41.5 14.0 50

2640 36.1 13.4 46

2830 32.9 13.1 42

2900 30.8 12.5 41

2990 30.8 12.9 40

2630 30.8 11.4 44

1290 70.3 12.7 70

1050 78.8 11.6 78

860 87.4 10.6 84

790 90.6 10.0 90

TABLE II

Derived Results Second Run Single-stage Motor

Speed r/min Corrected Torque Power Motor Inlet

Nm H.P. lbf/m ^a

580 46.8 3.8 50

870 46.8 5.7 50

790 45.7 5.1 50

1090 44.7 6.8 49

1450 43.6 8.9 50

1950 42.5 11.6 49

2340 39.3 12.9 48

2590 34.0 12.4 47

2850 30.8 12.3 42

3000 29.7 12.5 39

2840 29.7 11.8 40

2440 34.0 11.6 46

1790 51.1 12.8 58

1250 56.1 9.8 60

940 58.5 7.7 60

670 60.7 5.7 60

710 72.4 7.2 70

710 70.3 7.0. 70

760 70.3 7.5 71

1260 64.9 11.5 70

1380 61.7 12.0 68

1810 52.1 13.2 60

2150 43.6 13.2 52

1940 31.9 8.7 40

2570 29.7 10.7 40

TABLE III

Derived Results Third Run Single-stage Motor

Speed r/min Corrected Power Corrected Motor Inlet

Torque H.P. Airflow lbf/ln ^a

Nm ft ³ /min

.

590 47.9 4.0 266 50

740 41.5 4.3 269 50

930 46.8 6.1 301 50

1220 42.5 7.3 330 50

1720 42.5 10.3 393 49

1960 43.6 12.0 452 51

2460 39.3 13.6 489 50

2750 37.2 14.4 529 50

2880 35.1 14.2 527 48-

650 59.6 5.4 292 60

910 52.1 6.7 311 60

880 58.5 7.2 330 60 ^'

1200 56.4 9.5 368 60

1760 51.1 12.6 445 60

2280 47.9 15.3 507 62

2300 46.8 15.1 512 58

1680 61.7 14.6 489 72

1350 64.9 12.3 444 70

1080 67.1 10.2 417 70

750 68.1 7.2 356 70

720 72.4 7.3 349 70

750 70.3 7.4 339 70

DISCUSSION

1. The torque absorption characteristics of the dynamo¬ meter determined the lowest speed attainable in each series of tests. The dynamometer was calibrated using a moment arm and masses - corrected torque values are used in the derived results.

Accuracy of the digital readout is _+ digit i.e. +5 r/min and +^0,5 Nm

2. Air flow rates as measured by the flowrator were cor¬ rected for temperature and pressure using the manu¬ facturer's calibration curves.

3. The first and second run results (for the single stage motor) were obtained using the flowrator outlet pressure regulator to control the inlet pressure to the motor. This proved to be unsatisfactory, with the regulator unable to control the pressure as the flow rate increased.

4. The third, fourth and fifth runs were carried out with the, flowrator outlet pressure regulator removed from the air supply circuit.

5. The graphs set out in Figs. 9, 10 and 11 of the drawings show the results of tests carried out on the single-stage motor at 50, 60 and 70 lbf/in ³ inlet pressure respectively. Maximum speed in these tests was determined by the ability to supply air at the designated pressure to the motor. As pressure in¬ creased the maximum speed was reduced.