US3820923A

US3820923A - Single stage or multistage rotary compressor

Info

Publication number: US3820923A
Application number: US00301558A
Authority: US
Inventors: A Zweifel
Original assignee: AIRFINA Ets
Current assignee: AIRFINA Ets
Priority date: 1971-12-01
Filing date: 1972-10-27
Publication date: 1974-06-28
Anticipated expiration: 1991-06-28
Also published as: FR2164224A5; JPS5653112B2; DE2240018C3; CA962645A; GB1402435A; JPS4864509A; ES409115A1; DE2240018B2; DE2240018A1

Abstract

A rotary compressor with injection of the cooling medium into a compression chamber is characterized by having a rotary compression means journaled in a housing. The compression means is adapted to compress the fluid along a compression path from a fluid inlet to a fluid outlet. A plurality of nozzles inject the cooling medium into the compression chamber along a portion of the compression path. The smallest cell volume v1, into which the cooling medium is still being injected and the smallest closed cell volume v2, of the compressor exhibits the relation:

Description

United States Patent 1191 Zweifel June 28, 1974 [54] SINGLE-STAGE OR MULTISTAGE ROTARY 3,462,072 8/1969 Schibbye 418/98 RESS 3,542,497 11/1970 Chapuis 418/84 COMP 0R 3,684,412 8/1972 Harlin et a1 418/97 x [75] Inventor: Antonio Zweifel, Zurich,

Switzerland [73] Assignee: Airfina Etablissements, Vaduz Liechtenstein, Switzerland [22] Filed: Oct. 27, 1972 [21] Appl. No.: 301,558

[30] Foreign Application Priority Data Dec. 1, 1971 Switzerland 17508/71 July 7, 1972 Switzerland 10182/72 [52] U.S. Cl 418/84, 418/85, 418/87, 1 418/89, 418/99 [51] Int. Cl. 'F01c 21/04 v [58] Field of Search 418/87, 97, 98, 99, 85, 418/84, 89, 100, 228

[56] References Cited UNITED STATES PATENTS 1,558,620 10/1925 Kagi 418/97 3,088,660 5/1963 Voggenthaler 418/98 X 3,129,877 4/1964 Nilsson et a1. 418/99 3,138,320 6/1964 Schibbyc 418/99 3,178,104 4/1965 Williams 418/98 3,186,631 6/1965 Lamberton et al. 417/228 X 3,191,853 6/1965 Kroeger 418/97 3,191,854 6/1965 Lowler et al 418/97 X 3,289,651 12/1966 .linno 418/85 X 3,448,916 6/1969 Fraser 417/228 Primary ExaminerC. .l. Husar Assistant ExaminerLeonard Smith Attorney, Agent, or FirrnE. Janet Berry; Lawrence Rosen 5 7 ABSTRACT 0.40 s s +0.60 where 11/ v v jv In one embodiment, the number of cooling medium inlet nozzles are over 20 per compression path, the ratio of length to width of a nozzle orifice exceeds 10, its minimum width is less than 0.1 V7, where F denotes the sum of the cross-sectional areas of the nozzles.

24 Claims, 19 Drawing Figures PAIENTEDauuzemm 3:

sum uaor11 PATENTEDJUNZMM saw on ur 11 PATENTEDJUNZB w 3520.923

saw '05 ur 11' FIG .4

PATENTEUJUH28 I874 sum as or 11 l l g:

vlllllll'll u ll llilll EHL L PATENTEDMZB 1914 saw us er w PAIENTEDaunza um sum "10 or 11 SINGLE-STAGE OR MULTISTAGE ROTARY COMPRESSOR The present invention concerns a single-stage or multi-stage rotary compressor with injection of coolants into the compression chamber.

Rotary compressors in the form of sliding-vane compressors and screw-compressors are known where oil or any other liquid is injected into the compression chamber to cool the compression medium. Thorough tests have shown that their efficiency can be improved without major manufacturing costs. In this sense the present invention is characterized in that the number of injection nozzles for the coolant is over 20 per compression stage, and/or, if the ratio of length to width of a nozzle orifice exceeds 10, its minimum width is less than 0.1 F, where F is the sum of the injection surfaces of all nozzles per compression stage.

Embodiments of the subject of the invention will be described below on the basis of drawings. Air is assumed here as a compression medium and oil as the injected liquid, but all consideration can also be extended to other compression media and cooling liquids.

FIGJI shows a schematic representation of the construction of a rotary sliding-vane compressor with oil separation system in 'a section along the line [-1 of FIG. 3.

FIGS. 2, 2a, 2b, 2c, 2d show portions of the rotary sliding-vane compressor according to FIG. 1 with cylinder, rotor, oil injection system and combined regulating valve along the line IIII of FIG. 3 and in a perspective,

view resp. with two different positions of the rotor (2 and 2a) in the embodiments with injection nozzles (2, 2a, 2b) and injection slots (20, 2d).

FIG. 3 shows a longitudinal section through the portion of the rotary sliding-vane compressor along the line III-III of FIG. 2.

FIG. 4 shows a schematic representation of the construction of a screw compressor with oil separation system in a section along the line IV-IV of FIG. 7.

FIG. 5 shows adiagram of a rotary compressor in accordance with the ISO specifications, according to FIGS. I and 4 represented both for no-load and fullload.

view portions of the screw compressor according to FIG. 4 with cylinder male rotor, female rotor, oilinjection system (in FIGS. 6 and 60 only the injection nozzles for the male rotor are shown) and combined regulating valve along the line VVI of FIG. 9.

FIG. 7 shows a longitudinal section through the portion of the screw compressor along the line VII-VII of FIG. 6.

FIGS. 8, 80 show a development of the rotor surface of the screw compressor for two rotor positions. In these developments the location for intake, compression, the oil injection and the air delivery are visible. FIG. 8 shows the smallest cell volume 11 into which coolant is still injected, FIG. 8a the smallest closed cell volume 11 FIG. 9 shows a top view of the screw compressor according to FIG. 6 with suction flange and oil pump.

FIG. 10 shows a view of the screw compressor according to FIG. 6 from the rear, with injection flange, outlet and axial oil supply feeding.

In the schematic representation showing the construction of a rotary sliding-vane compressor in FIG. 1,

a lowercasing 1 is assembled with an upper casing 3'.

FIGS. 6, 6a, 6b, 6c, 6d show, partly in perspective I Connected to the casing 1, 3 is a cylinder 5 with the axis 6. A rotor 8 is mounted with its axis 9 eccentrically to the cylinder axis 6. The cylinder 5 is provided with one or several air intake ports 11 as well as a number of air outlet ports 12. The rotor 8 has substantially radially arranged sliding vanes 14 which hug the inner surface of the cylinder 5, due to the centrifugal force of the revolving rotor 8.

In the schematic representation of .the design of a screw compressor in FIG. 4, a lower casing 1 is assembled with an upper casing 3. Connected to the casings l, 3 is a double cylinder with the

axes

106 and 107.

take port, which cannot be seen in this section, and an air outlet port 12.

In the casing l, 3, both in the rotary sliding-vane as well as in the screw compressor (FIGS. 1 and 4), can be seen a first filter disk 16 with a relatively large filter surface (for example, felt), with corresponding oil pit 15 behind which is arranged a wire gauze 18 for retaining large drops formed on the disk 16. This filter 18 is joined, in the direction of the air flow, by a second filter disk whose surface is subdivided into an outer annular part 20 and into an inner annular part 21. The

corresponding oil pits

17 and 19 resp. are likewsie visible. After the outerannular part 20 is situated a wire gauze filter 22, after which the inner annular part 21 of the second disk is passed, and subsequently the delivery duct 24, the non-return valve 25 and the air connection 26. The oil pits l5, l7 and 19 are connected with the suction chamber of the compressor by an oil recover pipe 43 (FIGS. 3, 5).

The oil air mixture delivered by the compressor arrives in the lower casing l-, in which the oil deposits at the bottom, while the compressed air flows upward and is cleaned in the

filters

16, 18, 20-, 22 and 21 which follow. Subsequently the air flows through the non-return valve 25 which preceeds an air cooler 28 (FIG. 5). The oil flows into an oil cooler 27 (schematically represented in FIG. 5) to be cooled and then flows into intake 48 of a combined regulating valve 33. The oil then enters pre-chamber 52 where it is distribured through nozzles 54, 55 (bores or slots) and into the compression chamber. According to FIG. 2 and 6, the intake air or the intake gas flows over the combined multiple function-regulating valve 33 into a suction chamber 32. At the inlet of the suction chamber 32 is arranged a valve seat 34. The combined regulating valve 33, which regulates ON/OFF (principally it could also be regulated continuously by throttling the volume of air admitted and in screw compressors also by means of bypassing air inside the cylinder), also comprises a valve head 35 with a valve shaft 36. Its free end is connected to a control piston 38 in a control cylinder 37. The free end of the control cylinder 37 carries a connection 40 for the pressure medium (normally compressed air). In

the control piston 38 is embodied an insert 42.

The supply of the cooling oil to be injected into the compression chamber (it is also possible to use other liquids, for instance water), is effected from the lower casing 1 designed as an oil tank, which is under the final compression pressure, and from which oil is taken through a line and the cooler 27 (FIG. In order to increase the oil pressure, a pump 86 may be provided. The oil flows subsequently into a chamber 48 (FIGS. 2 and 6) and from there through a valve seat 50 into an oil pre-chamber 52. One end of the control piston 38 is designed as a valve body which controls the passage between the chamber 48 and the oil pre-chamber 52. Bores'53, which terminate in

nozzles

54 or 55, lead from the oil pre-chamber 52 into the interior of the cylinder 5 and 105 resp. In the above mentioned design with circular injection nozzles, these nozzles are arranged in relatively close rows (FIGS. 2 2a, 2b and 3 and 6, 6a, 6b respectively) like the bristles of a brush, so that the oil is charged uniformly distributed into the compressed air in the compression chamber 56. The oil can also be supplied through slot-shaped nozzles 55 (FIGS. 2c, 2d and 6c, 6d respectively.)

If we work with higher pressure ratios per stage (e.g., 8) good cooling is indispensable to prevent the air temperature from rising too much during the compression; because high air temperatures result in a poor efficiency, high thermal stress on the oil, irregular temperature distribution inside the compressor etc. The known oil-flooded compressors are so designed that the cooling liquid is injected through a relatively small number of nozzles, possibly prior to the compression, in order to utilize the highest oil-air pressure difference for the injection. This was based on the conviction that an oil mist would form which should absorb the heat generated during the compression of the air, thanks to its thorough mixing with the air and the small size of the droplets. This conclusion was apparently verified by the measurement of relatively low air temperatures at the delivery of the compressr or compression stage resp.

It was found that the desired oil mist is not formed by such an injection, due to the relatively low injection pressure and the relatively large diameter of the injection nozzles, but that the major part of the liquid passes over into relatively coarse drops, which cannot follow very well the airstream and which are therefore immediately separated. When the cooling liquid is injected only at the beginning of the compression, there are practically no more suspended oil drops in the air at the point where higher pressures prevail, and where due to the consequently higher air temperature, an intensive heat exchange is possible.

The air temperature will be correspondingly high there and cannot be determined by measuring the temperature at the outlet, because here liquid and air mix again so that the air temperature will be substantially lower than in the compression chamber. Furthermore the temperature measurement here represents the oil rather than the air temperature. Even with injection at higher air pressures, the obtained mixing of cooling liquid and air is rather poor, as long asthe liquid is not injected through many evenly distributed nozzles or through one or several thin slots. It required extensive research to find what advantages a uniformly distributed injection offers, particularly in the range of higher air pressures and air temperatures.

The known cooling system is also less effective in the sense that in some models because of premature aging the cooling oil must be changed after arelatively modcorresponding division into many individual nozzles,

arranged in the manner of bristles in a brush, with nozzle diameters between 0.3 and 1.2 mm, preferably about 0.8 mm, or one or several slots with a gap width of not more than 1 mm, preferably 0.3 mm, the cooling oil can be excellently distributed in the compression chamber in a finely atomized state. By impingement of the oil jets or spray (or in the case of injection through slots, of the oil curtains) on the rotor surface, the degree of atomization, and thus the distribution of the cooling liquid into the air tobe cooled can be improved. The air/oil mixture is also microscopically more homogeneous.

All these phenomena result in an effective cooling of the air and in an actually optimum utilization of the oil used for cooling. In addition the turbulence of the air in the compression chamber is improved by the great number of jets which results in an improvement both of the temperature and of the mass exchange, and therefore improves the effectiveness of the cooling oil.

The uniform distribution of the oil, particularly in the range of higher pressures, prevents leakage at most points. This improves not only the efficiency, but also the oil separation. The smallest oil drops, which render the oil separation difficult, are formed at higher air velocities, which can occur mainly at leaks.

In single-stage compressors with a pressure ratio of 8 and a ratio of 10 kg cooling oil per kg compressed air, we obtain an injection area F of about 1.5 sq.mm/rated horse power, where F denotes the sum of the injection cross-sections of all injection orifices. With circular nozzles with 0.8 mm diameter, we have thus 3 holes/- rated horse power. In the known rotary compressors, however, the number of injection nozzles per stage is less than 12, and the nozzle cross section is circular. With a rectangular cross section with a ratio of length to width of 10, for example, the number 12 corresponds to a nozzle width b of approx. 0.1 F In order to obtain air which is uniformly charged with oil during the compression, a much greater number of holes than 12 is therefore required in compressors with over 10 rated horse power, or with ratios of length to width of the nozzle orifice greater than 10, a minimum nozzle width substantially under 0.1 V F.

By cell volume we understand the volume of the enclosed space (cell) in which the air is contained during the compression. A cell volume as described below can also be defined after the outlet ports have been reached. In the rotary sliding-vane compressor, the cell volume is defined by the opposing faces of two successive blades or sliding-vanes and by the respective surface of the rotor and of the cylinder, considered as closed (FIG. 2). In the screw compressor, the cell volume is defined by the end wall and cylinder wall on the pressure side, considered as closed, and by the tooth flanks. By developing the rotor surface, it is possible to some extent to represent the three-dimensional cell volume two-dimensionally (FIGS. 8, 8a). There the male and

female rotor

108 and 110 respectively, are visible, as well as the points 112, 114 where the tooth combs hug the cylinder (see also FIG. 6). The end wall 170 on the suction side is interrupted by the intake 11, the end wall on the pressure side 169 by the outlet port 12. The complicated boundary 120 of the cell volume by the meshing of the teeth of the male rotor and of the female rotor is represented schematically in FIGS. 8 and 8a.

The smallest cell volume into which coolant is still injected is designated with V,, the smallest closed cell volume at which the cell reaches the first edge of an oil pocket or the first edge of an air outlet port (if there is no corresponding pocket provided) is designated with V In FIGS. 2, 2a, V corresponds to the hatched area CDEF, V to the area GHIK. In FIG. 8, V corresponds to the area ABCDEFGl-I, V to the area IKLMOPQR. In the above described compressor the following relation must apply. for each stage:

0.40 not greater than III not greater than l 0.60 with This means that the coolant itself is still beinginjected when the'cell has passed the first edge of an oil pocket or an outlet port, in which case V is smaller than V This arrangement ensures that a sudden undesired pressure rise, for example by a liquid stroke, cannot form in the cell, since the pressure can escape either through the injection nozzles 54 or injection slots 55 still connected to the cell, or through the air outlet ports 12 or oil pockets 58 already connected to the cell. To each outlet port 12 is assigned an oil pocket 58 in the rotary sliding-vane compressor (FIG. 2b).

In the known rotary compressors these values are in the range of As can be seen in FIGS. 1 and 4, the air outlet ports 12 are connected by a duct 59 with the lower casing 1, from which an air duct 60 leads to the

filters

16, 18, 20, 21 and 22. The plate-shaped

filters

16, 20, 21 are held on two

tie rods

61, 62 and 161, 162 respectively which bear on the

covers

64, 65, the tie rods being braced by means of nuts 63.

According to FIG. 3, the lateral covering of the cylinder 5 and of the rotor 8 is effected in the rotary slidingvane compressor by means of two two-part cylinder covers 69, 70 which serve to receive the

bearings

72, 73. In each cover 69, 70 is also arranged a stuffing-box ring 75, 76 which prevent outside air from getting into the bearings. Leakage air charged with oil mist flows through slots 77 between spacer rings 80 and the covers 69, 70 into the

bearings

72, 73 which are thus lubricated. The leakage air then flows through ducts 74 into the suction side of the compressor.

The rotor shaft ends are designated with 78 and 79. On one free end of the rotor shaft 79 is attached in the air-cooled model a cooling fan 81. Pressure oil ducts 82 lead from the oil pre-chamber 52 into the covers 69, 70. Lubricating and cooling oil is fed through ducts laterally to the rotor end faces as sealing liquid. For this purpose it is of advantage to supply the liquid only to one sector JH9 (FIG. 2a) of the rotor 8, which is defined by the smallest closed cell V GHIK. It is also As shown in FIG. 7, the lateral covering of the cyinder is effected in the screw compressors by means of two cylinder covers 169, which serve to receive the bearings 172, 173. In the cover 169 are also arranged two stuffing-box rings 175, 176 which prevent outside air from getting into the bearings. Leakage air containing oil mists flows through an annular slot 177 into the roller bearings 172 and 173 and from there through the bores 174 into the suction duct of the compressor.

Two control gear wheels 85 as well as an injection pump 86 can be arranged on the rotor shaft ends 179 and 183 preferably on the side opposite the drive. In the air-cooled model, this arrangement also includes a cooling propeller 81.

Pressure oil ducts 188 lead from the oil pre-chamber 52 into the cylinder-covers 169, 170'which supply cooling oil as sealing liquid through bores 182 laterally to the rotor end faces, so that the axial thrust of the rotor is at the same time partly compensated. Furthermore the oil ducts 184 are fed from the oil pre-chamber 52 and an axial injection from the end face on the pressure side is achieved through the nozzles 54. To this end it is of advantage to inject the cooling liquid only into the cell region limited by radial injection.

The valve 33 described above and represented in detail in FIGS. 2 and 6 is new in its design. It is a combination valve with coaxially arranged valve bodies which are connected with each other mechanically, either rigidly or elastically. It is actuated by a control medium, here compressed air, which acts only on one side of a piston. In the present case it performs the following functions:

Opening and closing the air intake, the cooling and lubricating oil, as well as additional oil supply with pressure-free oil carter during no load operation.

Relief valve in'case of current failure and sudden stoppage of the compressor.

The above described rotary compressor works as follows: (in this example only full-load or no-load operation) In the rotary sliding-vane compressor operating at full load the intake air to be compressed, with the rotat ing rotor 8, flows through the valve seat 34 (FIG. 2) into the suction chamber 32. Here it spreads and flows subsequently through the air intake ports 11 into the cylinder 5, where it is engaged by the sliding-vanes 14 of the rotating rotor 8 and moved in the direction of the arrow. During this process it is compressed due to the dimishing space between cylinder 5, rotor 8 and the corresponding sliding-vanes 14, the sliding-vanes 14 being pushed back into the rotor slots 8 by the inner cylinder wall' 7.

Due to the following compression, the air is heated quite considerably. In order to cool it, oil is injected through the nozzles 54 and resp. 55 into the corresponding compartment of the compression chamber.

The resulting oil spray or jets strike against the rotating rotor 8 where they atomize. The oil-air mixture as well as a swell of oil deposited on the bearing surface 7 of the cylinder 5 are pushed by the corresponding slidingvane 14 toward the pockets 58 and the air outlet ports namely during the time. in which the sliding-vane 14 passes by the outlet ports 12. In order to'prevent a sudden jerkey ejection of this liquid mass, the oil pocket 58 as well as several air outlet ports 12 are provided. There is thus sufficient volume available into which the liquid .can escape when asliding-vane 14 passes by, so thatv jerky ejections are avoided. Due to the fact that the pockets 58 extend inaddition beyond the openings 12, oil wedges'are formed on the pressure sidewhich reduce the leakage losses of compressed air toward the suction side. The running bearing surface of the cylin- "der isin'the region of the oil pocket 58 and air outlet ports v12- respectively, less'than 70 percent (preferably less than 50 percent) of the possible supporting surface of the entire cylinder width.

In the above described'screw compressor the fresh air to be compressed flows at full load through the valve seat 34 (FIG. 6)into'the suction chamber 32.

l2. Themajor' of the oil delivered with the air must be squeezed out from the narrowing gap between the rotor8 and the'cylinder in an extremely short time,

Here it flowsthrough the air intake ports 11 provided onthe cylinder end wall and on the cylinder barrel into the cylinder 105 There the suction starts by the tooth and tooth gap being disengaged on the end face, with the-male and

female rotor

108 and 110 respectively ro-. tating in the direction of the arrow, and with continued rotation,.both the tooth gap on themale rotor and that on thefemalerotor being released over their entire length. When the teeth are disengaged on the opposite end face, both tooth gaps are filled with air. With continued rotation the toothgaps on the suction side are closed by'the end wall. Later tooth and gap mesh again I on the suction side in the region opposite the intake. A

cell is thus formed which is bounded by the end wall on the pressure side, the cylinder andthe meshing tooth valve 25 out of the delivery duct 24 to the compressed air connection 26, and from there into an air receiver :or to the utilizer (not shown).., I

When the distribution net connected with the compressor has attained a provided maximumpressure, the compressor must switch automatically into its no-load position, in which the delivery of air stops, but not the lubrication nor the cooling of the rotor. The operating sequence is therefore as follows:

When the maximum'pressure is attained in the net,

a pressure switch 89 (FIG. 5) switches into the open position, a solenoid valve 91 feeds the control liquid and brings a servo-controlled slide-valve 92 into its noload position LpThe tap line-connected between the two

filters

20 and 21 is connected over the servo controlled slide-valve 92 with the outside ,air, so that the air blows off through this line. On the other hand, the system pressure is unchanged (since the latter is higher than the dropping pressure in the lowercasing g 1 (FIGS. 1 and 4), the non-return'valve 25 closes), so

flanks', in whichthe air is contained. Withcontinued rotation the'cell diminishes, since the point of engagement is displaced in the direction of the pressure side and the filled tooth gaps thus become shorter. The injectionof oil for cooling is effected on the cylinder barrel, in a similar manner as in the rotary sliding-vane compressor, thedistribution of the bores and slots resp. on the cylinder barrel corresponding to the cell form (FIGS. 6b,6d, 'and8), as well as on the end wall on the pressure side. Since there is no; friction due to slidingvanes etc. in the screw compressor, the injection of water instead of oil may be here of advantage. The

compression stops when the cell has reached the outlet I port 12 provided on the end face on the pressure side and on the cylinder barrel; oil pockets, which are of advantage ,in the rotary sliding vane compressor, are unnecessary here:

Both in the rotary sliding-vane and in the screw compressor the ejected mixture of air and oil flows subsequently through the duct 59 into the lower casing 1 (FIGS. 1 and 4), from which the compressed air flows through the air duct 60 and subsequently through the first filter plate 16.'Its area is relatively large, so that the velocity of flow of the-air is correspondingly slow. The degree of separation is, under otherwise equal conditions, lower at lowflow velocities. The successive refiltration is effected in the wire gauze filters 18 and 22, as well as in the second subdivided plate-shaped

filters

21, 20 with separately working parts. Due to this subdivision into partial surfaces and the resulting double flow through the filter plates 20, 2l'the air velocities in that the latter pushes a ball valve 93 into its left position (FIG. 5) .and a pressure is built up over the solenoid valve 91 and the pressure medium connection 40 (FIGS. -2, 5 and 6) under the control piston 38 which lifts the piston 38 and presses the valve head 35 above i the valve shaft 36 on the valve seat 34. The supply of intake air to the compressor is thus stopped.- During this closing movement, the'piston'38 hasclosed the valve seat also, and the coolant pumped by the oil pump 86 is returned 7 to the casing l by the excess: pressure valve 87. v i

Meanwhile, the air blows out of the casing 1 through the servo-controlled slide-valve 92 (FIG. 5) and the pressuredrops, causing the spring of the overflow valve 88 .to open for the oil pumped by the pump 86 to return into the casing 1, so that the oil circuit is'depressurized.

The shut-down of the intake air supply causes in the oil pre-chamber 52 (FIGS. 2 and 6) a negative pressure,

which is transmitted into the interior of the-piston 38 through the 'ports99,'now communicating with the said oil pre-chamber. As the chamber 48 is subject at first to the pressure developed by the oil pump 86, the ring valve 39 doses, but as soon as the oil circuit is depressurized by the opening of the overflow valve 88, 'the ring valve 39 opens under the action of a spring 97. Then oil' flowsfromthe' chamber 48 through the'ducts and the lateral ports 99 into the oil pre-chamber 52 and thence through the nozzles 54 and 5 5'into the compression chamber. The purpose of this reduced oil quantity is'to ensure lubrication and cooling of the compressor during the idling period.

Now, when consumption'reduces the pressure in the compressed air system below a specific minimum, the pressure switchi89 trips (FIG. 5), causing the solenoid valve 91 to takeup the position VJ? With the valve in that position, no further control medium'reaches the servo-controlled valve 92 or the piston 38,"so that the combined control valve opens under the suction prevailing in the'chamber 32 (FIGS. 2 and 6). The compressor begins to deliver, the pressure in the system system reaches that in the consumer system, the nonreturn valve 25 opens. The valve 93 shuts down against the consumer system, thus preventing any bypassing of the third filter 21 by the valve 93. The compressor delivers airto the charging system, i.e., to the air vessel, until this system also is completely charged. Then the compressor automatically switches to its idling position, as explained.

ln rotary compressors of the pumpless type, the oil pump 86, the excess-pressure valve 87 and the overflow valve 88 are redundant, but the circuitry and the control process remain substantially the same.

The above described compressors have a greater overall efficiency than the known compressors of this type, they have a higher volumetric efficiency, better oil separation, and a substantially lower oil consumption. The favourable cooling effect permits considerably higher pressure ratios per stage than heretofore with substantially the same efficiency. Thus where higher compression ratios are required the number of compression stages can be reduced 1 claim:

1. A rotary compressor with injection of the cooling medium into a compression chamber including in combination:

a housing positioned in the compressor;

fluid inlet means coupled to said housing and communicating with the compression chamber; fluid outlet means spaced from said fluid inlet means an disposed through said housing so as to communicate with the compression chamber;

rotary compression means journaled in said housing and adapted to compress the fluid along a compression path, the compression path including the area between the interior periphery of said housing and the external periphery of said rotary compression means as the latter mentioned means rotates from said fluid inlet means to said fluid outlet means; and

at least injection nozzles placed along the compresion path so as to communicate with the compression chamber and adapted to inject the cooling 'medium therein, the compression path defining a cell of varying and decreasing volume between said fluid inlet and outlet means wherein the smallest cell volume v into which the cooling medium is still being injected, and the smallest close cell volume v of the compressor exhibits the relation:

where and wherein the ratio of length to width of a nozzle orifice exceeds 10, its minimum width is less than 0.1 VT F denoting the sum of the cross-sectional areas ,of said plurality of injection nozzles.

2. A rotary compressor with injection of the cooling medium into a compressor chamber including in com bination:

a housing positioned in the compressor;

fluid inlet means coupled to said housing and communicating with the compression chamber;

fluid outlet means spaced from said fluid inlet means and disposed through said housing so as to communicate with the compression chamber; rotary compression means journaled in said housing and adapted to compress the fluid along a compres-.

sion path, the compression path including the area between the interior periphery of said housing and the external periphery of said rotary compression means as the latter mentioned means rotates from said fluid inlet means to said fluid outlet means; and

a plurality of injection nozzles placed along the compression path so as to communicate with the compression chamber and adapted to inject the cooling medium therein, said compression path defining a cell of varying and decreasing volume between said fluid inlet and outlet means wherein the smallest cell volume v into which the cooling medium is still being injected, and the smallest close cell volume v of the compressor exhibits the relation:

O.40 s 1!; s 0.60

where ll! v v /v 3. The rotary compressor as in claim 2 wherein said I plurality of injection nozzles are circularly shaped and 5. A rotary compressor with injection of the cooling medium into a compression chamber including in combination:

a housing positioned in the compressor;

fluid inlet means coupled to said housing and communicatingwith the compression chamber;

fluid outlet means spaced from said fluid inlet means and disposed through said housing so as to communicate with the compression chamber;

rotary compression means journaled in said housing and adapted to compress the fluid along a compression path, the compression path including the area between the interior periphery of said housing and a portion of the external periphery of said rotary compression means as the latter mentioned means rotates from said fluid inlet means to said fluid outlet means; and

a plurality of injection nozzles disposed through said housing and placed along the compression path so as to communicate with the compression chamber and adapted to inject the cooling medium therein, the compression path'defining a cell of varying and decreasing volume between said fluid inlet and outlet means wherein the smallest cell volume v into which the cooling medium is still being injected, and the smallest closed cell volume v of the compressor exhibits the relation:

0.40 s q, s. +0.60

where and wherein the ratio of length to width of a nozzle orifice exceeds 10, its minimum width is less than 0.1 VT, F denoting the sum of the cross-sectional areas of said plurality of injection nozzles.

6. The rotary compressor as in claim wherein each orifice has a substantially circular profile and has a diameter ranging from approximately 0.3 to 1.2 mm.

7. The rotary compressor as in claim 5 wherein said plurality of injection nozzles are distributed along the interior periphery of said housing so as to be substantially parallel to the longitudinal axis thereof.

8. The rotary compressor as in claim 5 wherein at least one of said plurality of injection nozzles communicates with the smallest closed cell volume.

9. The rotary compressor as in claim 5 wherein said housing is substantially cylindrically shaped and includes two substantially parallel opposed end walls, each of the end walls including a plurality of openings adapted to supply oil thereat to act as'a sealing and lubricating fluid for the ends of said rotary compression means positioned adjacent thereto.

10. The rotary compressor as in claim 9 wherein said rotary compression means further includes bearing means positioned in each of the end walls for rotatably journaling the former mentioned means, and aperture means disposed through the end walls and adapted to communicate with and tap a portion of the compressed fluid and direct same to lubricate said bearing means,

said aperture means further including ducts to egress said portion of the compress fluid in an area adjacent said fluid inlet means.

11. The rotary compressor as in claim 5 further including an output path coupled to said fluid outlet means and guiding the compressed fluid therefrom, said output path further including filter means interposed therealong to filter the compressed fluid as it transverses therethrough.

12. The rotary compressor as in claim 11 wherein said filter means comprises a filter plate, a filter housing dividing said filter plate into an included inner part and an outer part, the latter part defined around the inner part, said housing including baffles to direct the compressed fluid therethrough so that said filter plate experiences the compressed fluid flow in opposed directions. j

13. The rotary compressor as in claim 5 wherein said rotary compression means is a pair of cooperating screw rotors.

14. The rotary compressor as in claim 5 wherein said rotary compression means is a sliding-vane rotor and wherein said plurality of injection nozzles are disposed in a nozzle array of at least three rows.

15. The rotary compressor as in claim 14 wherein the array of nozzle rows are arranged so as to be parallel to the longitudinal axis of said housing.

16. The rotary compressor as in claim 14 wherein a portion of the area defined on the inside periphery of said housing located between the last one of said plurality of injection nozzles and said inlet means, and drawn so as to include said outlet means is less than 50 percent of the entire inside peripheral area of said housing.

17. The rotary compressor as in claim 5 wherein said fluid outlet means comprises a plurality of outlet ports positioned on the interior periphery of said housing so 12 as to be substantially parallel to the longitudinal axis thereof.

18. The rotary compressor as in claim 17 wherein each of said plurality of outlet ports communicates with a recess having a larger cross-sectional area then its respective one of each of said plurality of outlet ports, each of said recess being defined on the interior peripheral wall of said housing and adapted to facilitate the egress of oil and to facilitate isolation of said fluid inlet means from the compression chamber.

19. The rotary compressor as in claim 11 wherein said filter means includes a first filter serially interposed along the the output path and a second filter positioned further along the output path and parallel spaced from said first filter, each of said first and second filters being substantially disc-shaped.

. 20. The rotary compressor as in claim 19 further including a wire gauge filter interposed between said first and second filters and adapted to filter the cooling medium suspended in the compressed fluid as it transverses therethrough.

21. The rotary compressor-as in claim 19 wherein said second filter includes a filter housing that divides said second filter into an included inner annular part and an outer annular part, the latter part disposed around and including the inner part, said housing directing the compressed fluid serially through the outer annular part and then through the inner annular part, the outer annular pary having a surface area 1.5 times greater than the surface area of the inner annular part.

22. The rotary compressor as in claim 5 further including an input path coupled to said fluid inlet means,

an output path communicating with said fluid outlet means, a pre-chamber adapted to supply the cooling medium to said plurality of nozzles, regulating-valve means on one end adapted to regulate and block the flow of air through the input path, and on the other end adapted to regulate the flow of the cooling medium into said pre-chamber, said other end being coupled and responsive to the output of the rotary compressor.

23. The rotary compressor as in claim 22 wherein said other end of said regulating valve means includes a control piston, a control cylinder slidably retaining said control piston, a valve seat comprising the input to said pre-chamber, said control piston being driven by the output of the rotary compressor so that when a predetermined output pressure is reached said one end of said regulating-valve means blocks the flow of air through the input path while concomitant therewith said control piston engages said seat of said prechamber to block the flow of cooling medium therethrough.

24. The rotary compressor as in claim 23 wherein said control piston includes a substantially hollow enclosed piston skirt, aperture means disposed through the walls of said piston skirt, ring-valve means adapted to ride within said piston skirt and spring means biasing said ring-valve means so that when said piston skirt abuts against said valve seat to block the flow of cooling medium to said pre-chamber, said spring means lifts said ring-valve means from said piston skirt allowing a portion of the cooling medium to flow therearound to egress said aperture means into said pre-chamber and flow through said plurality of nozzles thereby lubricating and cooling said rotary compression means.

. Tfimrrn STATES MTENT arr-fur CERTIFICATE. jOF (IDRECTEQN Patent No. 3,826,923 Dated June 28, 1974 Igventor(s) :kntonio Zwei fel It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In column 319 claim line Bl the number 061" should read 1.0

Signed and sealed this 18th day of February 1975.

(SEAL) Attest C. MARSHALL DANN RUTH C. MASON Commissioner of Patents Attesting Officer and Trademarks FORM PO-lOSO (10-69) USCOMM-DC 60376-P69 U.5. GOVERNMENT PRINTING OFFICE: I969 0-366-334,

Claims

1. A rotary compressor with injection of the cooling medium into a compression chamber including in combination: a housing positioned in the compressor; fluid inlet means coupled to said housing and communicating with the compression chamber; fluid outlet means spaced from said fluid inlet means an disposed through said housing so as to communicate with the compression chamber; rotary compression means journaled in said housing and adapted to compress the fluid along a compression path, the compression path including the area betweeN the interior periphery of said housing and the external periphery of said rotary compression means as the latter mentioned means rotates from said fluid inlet means to said fluid outlet means; and at least 20 injection nozzles placed along the compresion path so as to communicate with the compression chamber and adapted to inject the cooling medium therein, the compression path defining a cell of varying and decreasing volume between said fluid inlet and outlet means wherein the smallest cell volume v1, into which the cooling medium is still being injected, and the smallest close cell volume v2, of the compressor exhibits the relation: -0.40 < OR = psi < OR = +0.60 where psi v1 - v2/v2, and wherein the ratio of length to width of a nozzle orifice exceeds 10, its minimum width is less than 0.1 square root F, F denoting the sum of the cross-sectional areas of said plurality of injection nozzles.

2. A rotary compressor with injection of the cooling medium into a compressor chamber including in combination: a housing positioned in the compressor; fluid inlet means coupled to said housing and communicating with the compression chamber; fluid outlet means spaced from said fluid inlet means and disposed through said housing so as to communicate with the compression chamber; rotary compression means journaled in said housing and adapted to compress the fluid along a compression path, the compression path including the area between the interior periphery of said housing and the external periphery of said rotary compression means as the latter mentioned means rotates from said fluid inlet means to said fluid outlet means; and a plurality of injection nozzles placed along the compression path so as to communicate with the compression chamber and adapted to inject the cooling medium therein, said compression path defining a cell of varying and decreasing volume between said fluid inlet and outlet means wherein the smallest cell volume v1, into which the cooling medium is still being injected, and the smallest close cell volume v2, of the compressor exhibits the relation: -0.40 < or = psi < or = + 0.60 where psi v1 - v2/v2.

3. The rotary compressor as in claim 2 wherein said plurality of injection nozzles are circularly shaped and have a nozzle diameter of less than 0.1 mm.

4. The rotary compressor as in claim 2 wherein said plurality of injection nozzles are circularly shaped and have a nozzle diameter of approximately 0.3 to 1.2 mm.

5. A rotary compressor with injection of the cooling medium into a compression chamber including in combination: a housing positioned in the compressor; fluid inlet means coupled to said housing and communicating with the compression chamber; fluid outlet means spaced from said fluid inlet means and disposed through said housing so as to communicate with the compression chamber; rotary compression means journaled in said housing and adapted to compress the fluid along a compression path, the compression path including the area between the interior periphery of said housing and a portion of the external periphery of said rotary compression means as the latter mentioned means rotates from said fluid inlet means to said fluid outlet means; and a plurality of injection nozzles disposed through said housing and placed along the compression path so as to communicate with the compression chamber and adapted to inject the cooling medium therein, the compression path defining a cell of varying and decreasing volume between said fluid inlet and outlet means wherein the smallest cell volume v1, into which the cooling medium is still being injected, and the smallest closed cell volume v2, of the compressor exhibits the relation: -0.40 < or = psi < or = + 0.60 where psi v1 - v2/v2, and wherein the ratio of length to width of a nozzle orifice exceeds 10, its minimum width is less than 0.1 Square Root F, F denoting the sum of the cross-sectional areas of said plurality of injection nozzles.

6. The rotary compressor as in claim 5 wherein each orifice has a substantially circular profile and has a diameter ranging from approximately 0.3 to 1.2 mm.

9. The rotary compressor as in claim 5 wherein said housing is substantially cylindrically shaped and includes two substantially parallel opposed end walls, each of the end walls including a plurality of openings adapted to supply oil thereat to act as a sealing and lubricating fluid for the ends of said rotary compression means positioned adjacent thereto.

10. The rotary compressor as in claim 9 wherein said rotary compression means further includes bearing means positioned in each of the end walls for rotatably journaling the former mentioned means, and aperture means disposed through the end walls and adapted to communicate with and tap a portion of the compressed fluid and direct same to lubricate said bearing means, said aperture means further including ducts to egress said portion of the compress fluid in an area adjacent said fluid inlet means.

12. The rotary compressor as in claim 11 wherein said filter means comprises a filter plate, a filter housing dividing said filter plate into an included inner part and an outer part, the latter part defined around the inner part, said housing including baffles to direct the compressed fluid therethrough so that said filter plate experiences the compressed fluid flow in opposed directions.

17. The rotary compressor as in claim 5 wherein said fluid outlet means comprises a plurality of outlet ports positioned on the interior periphery of said housing so as to be substantially parallel to the longitudinal axis thereof.

20. The rotary compressor as in claim 19 further including a wire gauge filter interposed between said first and second filters and adapted to filter the cooling medium suspended in the compressed fluid as it transverses therethrough.

21. The rotary compressor as in claim 19 wherein said second filter includes a filter housing that divides said second filter into an included inner annular part and an outer annular part, the latter part disposed around and including the inner part, said housing directing the compressed fluid serially through the outer annular part and then through the inner annular part, the outer annular pary having a surface area 1.5 times greater than the surface area of the inner annular part.

22. The rotary compressor as in claim 5 further including an input path coupled to said fluid inlet means, an output path communicating with said fluid outlet means, a pre-chamber adapted to supply the cooling medium to said plurality of nozzles, regulating-valve means on one end adapted to regulate and block the flow of air through the input path, and on the other end adapted to regulate the flow of the cooling medium into said pre-chamber, said other end being coupled and responsive to the output of the rotary compressor.

23. The rotary compressor as in claim 22 wherein said other end of said regulating valve means includes a control piston, a control cylinder slidably retaining said control piston, a valve seat comprising the input to said pre-chamber, said control piston being driven by the output of the rotary compressor so that when a predetermined output pressure is reached said one end of said regulating-valve means blocks the flow of air through the input path while concomitant therewith said control piston engages said seat of said pre-chamber to block the flow of cooling medium therethrough.