US2097037A - Rotary compressor or vacuum pump - Google Patents

Description

Oct. 26, 1937.- A. J. NORTHEY 2,097,037

ROTARY COMPRESSOR OR VACUUM PUMP Filed July 24, 1934 2 Sheets-Sheet J.

i 3 I/vvE/vTo'R m 4% A.J '/V0RT 7 Y HTTYS Patented Oct. 26, 1937 PATENT OFFICE 2,097,037 ROTARY COMPRESSOR OR VACUUM PUMP Arthur John Northey, Parkstone, England, 38-' signer to Northey Rotary Engines limited,

Townsville, Australia Application July 24, 1934, Serial No. 736,797 In Great Britain August 25, 1933 3 Claims.

This invention relates to rotary air or gas compressors, vacuum or liquid pumps or similar devices, more particularly of the kind comprising a pair of cylindrical chambers which intersect or penetrate one into the other and each fitted with a rotor comprising a cylindrical body portion of less diameter than thecylinder and a pro-' jecting arm or piston, extending towards the cylinder walls., These rotors are mounted upon parallel shafts one in each of the cylinder spaces, and each rotor body is suitably cut away so as to allow the associated projecting arms or pistons to pass one another in the course of their revolution. The shafts carrying the rotors may be suitably geared together or otherwise arcient compression or evacuation of charges ofair or other gaseous fluid.

Another object of the invention is to provide an improved form of liquid pump. A further object of the invention is to proville an improved form of motor driven by compressed air or by water power.

The invention consists in a compressor, vacuum pump, or liquid pump, or similar device in which a pair of coacting bladed rotors, ro-

ta'ting in opposite directions within a chamber, and drawing in a charge of air or other gaseous fluid, or liquid between the trailing sides of the blades simultaneously with the compression on the leading sides of said blades of the charge previously drawn in, is designed so that any compressed charge remaining in the chamber when the delivery valve closes, does not become a loss as in a reciprocating compressor, but expands into the suction charge already drawn in thereby raising the" pressure thereof,.practically the whole of the remainder of the compressed charge being on the leading or compression side of'the rotor tips on the next stroke of the rotors: The invention also consists in the further features hereinafter described and claimed.

Referring now to the accompanying drawings: Figure 1 is a cross-sectional view of a compressor constructed according to the invention and Figure 2 a longitudinal sectional elevation thereof; 7

Figure 3 a view similar to that shown in Figure 1 of amodified form of compressor, and

Figure 4 a longitudinal sectional plan thereof;

Figure 5 one arrangement for by-passing the charge from the compression side of the rotors to the induction side thereof.

In carrying the invention into effect according to the; embodiment illustrated in Figures 1 5 and 2, the compressor or evacuatorcomprises a main water cooled chamber a which is formed by two intersecting cylindrical bores. Within these bores two rotors band b revolve simultaneously in opposite directions, being carried on two parall0 lel shafts c and c which are concentric with v the bores.

The rotors b and b are each formed with a blade d which projects outwards towards the inner wall of each of the bores of the chamber a 15 and are provided with recesses or pockets e on their peripheries to enable the blades 11. to perform a complete revolution. The rotor shafts c and c are each provided at one end with a gear wheel I, the two gear wheels being of the 20 same size and meshing one with the other so that the rotors are maintained in correct angular relationship one to the other and no variation in relative angular velocity can take place between them. The rotors may be driven by any suitable motor, either electric, internal combustion or other form, connected to the driving member g mounted upon one of the rotor shafts c and c'..

In the upper'and lowerwalls of the chamber 30 i a, near the point of intersection of the two bores constituting the said chamber, are provided inlet and exhaust ports h and i which are controlled by non-return valves ;i-and k respectively, the valve i controlling the air or other gaseous fluid 35 passing through the inlet h from the conduit Z whilst the valve 7c controls the air expelled through the conduit m.

The rotors b and b revolve in the direction in 50 dicated by the arrows in Figure 1, and as they move from the position shown in this figure which f is the commencement of the suction stroke, the 7 volume enclosed between the trailing sides of the blades (1 increases and air or other gaseous fluid 55 .ports u.

usually governed by the amount of loading on the.

non-return discharge valve k, the air or other gaseous fluid under pressure will be discharged through the conduit m into a tank or reservoir 2 (Figure 5) or wherever it is required.

The end of the compression stroke is reached whenthe blades on the rotors reach a position immediately above the delivery valve k. The position of the.rotors at this stage is approximately that shown in Figure 1 except that they are inverted. By the time the rotors reach this position, mostof the compressed air or other gaseous fluid will have been expelled through the delivery valve k.

As the rotors move on from the position repre-, senting the end of the compression stroke, the

two blades move upwards, lying between the two rotor shafts. Both valves 7' and It automatically close andany small volume of compressed air or other gaseous fluid which may be contained in the space 8 is released and expands through the whole chamber a, raising the pressure therein to a value above that of atmosphere, that is to say, the chamber is supercharged. When the rotors againreach the position shown in Figure l, practically the whole of the supercharged air or other gaseous fluid will be contained in the space on the leading side of the rotors, that is in the volume which is being compressed. The only part of the charge which must fall to atmospheric pressure before further air can be drawn in, ,is that then contained in the space s and as this is a very small percentage of the total volume or air or other gaseous fluid its effect on the efllciency is negligible. The supercharging effect will naturally be greater the higher the delivery pressure of the compressor. k

In the modified form of compressor illustrated in Figures 3 and 4 the non-return valves :i and k are dispensed with, the inlet and outlet portst and u being directly controlled by the rotors b and b. The said ports t and u maybe arranged in pairs in the side walls of the chamber a, one on either side of each of the rotors, the inlet ports t being in alignment 'asare also the outlet The inlet" ports t, communicate by means of the passages v in the compressor casing,

.with the air or other gaseous fluid inlet conduit w whilst the outlet ports u are in communication with the air or other gaseous fluid..outlet conduit :1: by means of the passages 11.

The ports 1." and u are of curved segmental shape'and adapted to "be opened and closed by the rotors which are of the same shape as those already described with reference to Figures 1 and 2.

It will be seen from Figure 3 that the compressor operates in a similar manner to that shown in Figures 1 and 2, the blades d moving in the direction of the arrows to commence the induction stroke. As the blades move apart the inlet port t is uncovered by its rotor b so that air or other gaseous fluid is drawn through the conduit w and passages 12 into the space s between the blades. Furthermovement of the rotors causes the outlet port it to be uncovered by the 1 and discharge conduit 3:. The rotors now reach a position approximately similar to that shown in Figure 3 except'that they are inverted. Both the inlet and the outlet ports t and w are now. closed by their respective rotors and any small 5 pocket of compressed air remaining is trapped in the space s between the blades as in the arrangement shown in Figures 1 and 2. This pocket of compressed air or other gaseous fluid is expanded into the chamber a in a similar manner to'that already described, as the blades move upwards, thereby raising the pressure to a value above that of the atmosphere.

It will be clear from the above description that the induction and compression stages are pro- 15 duced in a common chamber. by means of a continuous and uniform rotary motion, so that no inertia forces have to be considered. The compressor may be perfectly balanced, and as the bearings and gears are the only wearing parts, speed of revolution is not limited by mechanicai considerations. The radial and axial clearances by the rotors are verysmall, so that the leakage losses are low and the volumetric efliciency is maintained in service, while for the same reason as no internal lubrication is absolutely necessary, the air or other gaseous fluid may be compressed and delivered free from any lubricating oil vapour. In some applications this. point is of importance, but probablythe main advantage of the design is that it combines the positive delivery at relatively high pressures of a reciprocating compressor with high speeds oi revolution, so that output in relation to weight and cost is very favourable.

A compressor as above described when used for road compressor work or any work where the amount of air used is varying, can be controlled or governed by by-passing the air fromthe compressionside of the rotors to the induction side 40 thereof.

One such arrangement is shown diagrammatically in Figure 5, according to which a by-pass conduit I extends from the compression side of the rotors to the suction side thereof, and has mounted therein a spring loaded valve 2. The said valve normally cuts off communication between the discharge conduit m and the suction side of the compressor, the compressed charge being discharged into the tank or reservoir 2 50 through the conduit 3 which latter is provided with a non-return valve 4. As soon as the pressure within the tank or reservoir 2 reaches a predetermined pressure the valve 21s raised from its seat by any suitable -means such as a pressure operated piston or electric device controlled by the pressure in the tank 2:, thereby allowing any further charges to pass up through the by-pass I to the suction side of the compressor.

By automatically controlling the time of opening of the by-pass valve by spring means or other governor, the pressurein the container can be keptat any desired mark whether the amount of air used be little or up to the maximum output of the compressor.

The device constituting the invention may also be used for pumping liquids and may be particularlyadapted for use as asuction or vacuum pump.

It can also be used as a motor driven by compressed air as, for example, in the operation of pneumatic tools or may be driven by water.

1. A compressor or vacuum pump comprising the combination of apair of cylindrical chambers 75 which intersect or penetrate one into the othe a pair of co-acting contacting cylindrical rotors,-

rotatable in opposite directions within said chambers, means for admitting air to said chambers and cutting it off, and means for delivering air therefrom and cutting off said delivery. a blade on each said rotors, extending outwardly toward the casing and a recess in each said rotors. adia-v cent its blade, the blade on the recess side and the recess on the blade side forming a continuous concave curve, the constructionand arrangement being such that the air is compressed between the leading radial surfaces 6: the two blades, and the recess and blades serve to transfer the compressed gas remaining in the recess after the closing of the delivery means, to the suction side of the compressor.

2. A compressor as claimed in claim 1 in which the means for admitting air-to said chambers and cutting it oil, and the means for delivering air therefrom and cutting oi! said delivery, comprises inlet and delivery ports arranged in each side of the chambers adjacent to thesides of the rotors so as to be covered and uncovered by the bodies of saldrrotors as they rotate.

3. A compressor as claimed in claim 1 in which the means for admitting air to said chambers and cutting it off, and the means for delivering air therefrom and cutting oil! said delivery, comprises inlet and delivery'ports arranged in the rotor casing and which-are opened and closed by means ot-non-return valves.

ARTHUR J OHN RORTHEY;

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