HIGH OUTPUT ROTARY COMPRESSOR

Abstract: Improved compressor comprising a stator (101) and a rotor (108) having vanes. The rotor is supported on a hollow axis (109) which comprises a valve assembly (135) having inlet and outlet valves. The air to be compressed enters the compressor through a hole (120) in the stator and is fed to the interior of the hollow axis (109) and thence through a one-way valve to the corresponding compression chamber. The compressed air is fed through outlet valves to a space (138) in the valve assembly (135) and then to a radially adapted outlet (143). Since the outlet and the inlet valves are adapted close to the centrum of the rotor, one-way valves of steel spring membrane type may be used. According to the invention, the gable (105) of the stator is provided with a shunt conduit (151) which connects the dead space at the position of the compression chamber having smallest volume with the diametrically opposite chamber having greatest volume for transferring the compressed air in the dead space for reuse. Different placement of said shunt conduit is described.

Description: High output rotary compressor Field of invention The present invention relates to an improved vane compressor of the type described in our international patent application No. PCT/SE84/00133 (WO 84/04137). The invention increases the com- pression rate achieveable with a certain size of the compressor or the amount of compressed air provided by this compressor. In this way a series connection of several compressors in order to provide a certain compression rate or an increase of the dimensions of the compressor in order to obtain an increased through-put capacity may be avoided. Prior art The above-mentioned international patent application No. PCT/5E84/00133 (WO 84/04137) relates to a vane compressor having inlet and outlet valves adapted in the excentric rotor of the compressor. Th ' e inlet and outlet valves are pressure operated and open when the atmosphere pressure is underpassed and the counter- pressure is exceeded, respectively. Moreover, the inlet and outlet valves are interconnected in pairs through a hydraulic system in order to open and close substantially simultaneously on the diametrically opposite sides of the rotor.. Further similar compressors are described in the French patent specifications FR-A-826 424 and FR-A-1 261 674. In the Swedish patent specification SE-B-333 791 there is diosclosed a vane compressor having a means for connecting the compression space to the inlet in order to decrease the output pressure. Thus, a partial short circuit is formed which decreases the pressure obtained. Summary of the invention The object of the present invention is to provide a compressor in which the inlet and outlet valves are positioned in the rotor axis and in absence of centrifugal forces are completely pressure operated in order to be able to open at a suitable time merely in response to the pressure conditions prevailing. Moreover, it is an object of the present invention to provide a compressor having a higher output pressure or a higher through-put capacity compared to previously known compressors, which improvement may be achieved without changing the dimensions of the stator and the rotor and their relative excentricity, respectively. Thus, there is provided a means at a vane compressor comprising a stator and an excentric rotor with vanes positioned therein, defining several compression chambers, and inlet and outlet valves or openings for permitting input of air or gas into each chamber in a position thereof, in which an underpressure prevails in relation to the suction pressure of the compressor, and permitting output of air or .gas from each, chamber in a position thereof,, in which an overpressure prevails in relation to the counterpressure. According to the invention, the inlet and outlet valves are positioned in an axis of the rotor and are merely pressure operated. Said axis is hollow and the inlet air to the compressor passes through the interior of the hollow axis to said inlet valves. Also the outlet air from the compressor passes from the outlet valves to the interior of the hollow axis and thence to the outlet of the compressor. According to another feature of the invention, a shunt conduit is adapted for connection of a first chamber of the compressor with an essentially diametrically opposite second chamber of the com- pressor in the position of the first chamber where the output of air substantially has been terminated for transfer of the remaining air with a high pressure to the second chamber in the position thereof, in which it substantially has terminated the suction stroke. The shunt conduit may be adapted in the stator and extends from a first position of the stator which substantially corresponds to the position of the front vane of the corresponding first chamber being in its position with the smallest volume, and to a second position of the stator substantially diametrically opposite thereto, which substantially corresponds to the position of the front vane of the corresponding second chamber being in its position with the greatest volume. Alternatively, the first mouth of the shunt conduit may be between the vanes of the first chamber being in its position of smallest volume. The shunt conduit may be provided with one-way valves at the first and/or the second mouth. If the speed of operation of the one-way valves are insufficient, the rotor may be provided with recesses between the vanes, which recesses operate as valves for the first mouth of the shund conduit and open the conduit as soon as the rotor has passed the position for its smallest volume. Each recess may be defined by a rim surface which is parallel to the radie of the rotor and a surface which is perpendicular to the radie of the rotor, so that the recess is a half sector. The shunt conduit is adapted in the gable or the gables of the stator or in the cylindrical housing of the stator. The shunt conduit may be provided with an accumulator between the first and second mouth thereof. In ' a preferred embodiment of the invention, the shunt conduit is however adapted in the rotor and comprises valves adapted to open and close the shunt conduit at the intended pressure conditions. The shunt conduit is a ring-shaped or radial channel adapted in the rotor and connected with each compression chamber through separate holes, which comprises valves adapted to open and close the input in the ringshaped channel and the output from the ring-shaped channel, respectively. These valves are preferably valves adapted in each vane. By the invention there is provided a compressor in which the inlefe and outlet valves are positioned in the interior of the hollow axis of the rotor. These valves are completely pressure operated and thus open by themselves when the pressure conditions are those necessary. By means of the shunt conduit there is further provided that the amount of air with high pressure which is left in the rotor chamber after the output stroke is transferred to another rotor chamber immediately after its suction stroke in order to increase the pressure and the amount of air in the last-mentioned chamber. In this way, the air which is left in the so called dead space of the compressor is used and the efficiency of the compressor is increased in this way. Of course, the necessary drive power will be corre¬ spondingly increased. In another preferred embodiment, the compressor comprises two identical compressor halves, which are alternatively parallel- and series-connected by an exchangable valve assembly positioned in the interior of a common hollow axis. At the series connection, the first compressor half is provided with said shunt conduit in order to increase its volume through-put, whereby the two halves are adapted to each other. Brief description of the drawings The invention is described in details below by means of preferred embodiments of the invention and with reference to the appended drawings. Fig. 1 is a cross section through a compressor according to previously known technique. Figs. 2 - 7 are schematic cross-sectional views through a compressor essentially according to Fig. 1 provided with a shunt conduit according to the present invention and show succeeding positions of the rotor during a cycle. Fig. 8 is a plan view of a vane divided into two halves. Fig. 9 is a schematic view of a preferred embodiment of the invention. Fig. 10 is a schematic cross-sectional view through another embodiment of the compressor according to the invention. Figs. 11, 12 and 13 are cross-sectional views taken according to the lines XI-XI, XII-XII and XIII-XIII in Fig. 10. Fig. 14 is a schematical cross-sectional view through a valve device used in the compressor according to Fig. 10. Fig. 15 is a cross-sectional view taken according to the line XV-XV in Fig. 14. Fig. 16 is a cross-sectional view similar to Figs. 12 and 13 comprising said shunt channel in the rotor. Fig. 17 is a cross-sectional view of a valve assembly according to the invention. Fig. 18 is a side view according to the line XVIII-XVIII in Fig. 17. Fig. 19 is a side view according to the line XIX-XIX in Fig. 17. Detailed description of the invention In Fig. 1 there is shown a compressor according to previously known technique, specifically according to the above-mentioned international patent application PCT/SE84/00133. The compressor comprises a housing or a stator 15 and a rotor 14 positioned in the stator. The rotor is excentrically journalled and is composed of four segments, each occupying a fourth of the cross section of the rotor. Each segment comprises an inlet opening 16 for air having an inlet valve 19, 23 and an outlet opening 17 having an outlet valve 20, 24. The inlet valve 19, 23 opens to a compressor chamber 46 between the rotor and the stator and permits the air to flow into the chamber 46 as soon as the pressure in said chamber 46 is below the pressure in the inlet opening 16, which usually is the atmosphere pressure. The outlet valve 20, 24 also opens to the chamber 46.between th ' e rotor and the stator and permits the air to flow out from the chamber 46 as soon, as the pressure in said chamber 46 is higher than the pressure- in the outlet opening 17. In this way there is provided a pressure operated flow of air into and out from the chamber 46. Each inlet valve 19, 23 is connected to the corresponding diametrically opposite outlet valve 20, 24 in order to forcedly open and close at the same time and to balance the centrifugal forces in relation to each other. Moreover, vanes 47, cf. Figs. 2 - 7, are positioned in the rotor between each sector in order to define each chamber 46 in a previously known manner. Of practical reaons it is not possible to obtain too high compression rates since the distance between the rotor and stator cannot be decreased too much. Thus, there is formed a chamber having a certain smallest volume, which chamber usually is called the dead space. In Fig. 4 there is schematically shown the stator 15 having the rotor 14 in the position in which the chambers 30 and 31 (corresponds to the chamber 46) are greatest and smallest, respectively. The chamber 30 has sucked air inside said chamber during the previous positions shown in Figs. 2 and 3. In the position according to Fig. 4, said chamber 30 is closed by closing a valve 19, which in the figure is shown as a simple one-way valve. The corresponding is true for the chamber 31 which in the positions shown in Figs. 2 and 3 has compressed the air enclosed therein and in the position according to Fig. 4 has achieved its greatest compression, at which position the one-way valve 20 is closed. The one-way valve 20 was opened when the pressure in the chamber reached .the counterpressure, e.g. in the position according to Fig. 2. In Fig. 4 there is shown a conduit 32 which connects the chamber 31 with the chamber 30 as soon as the rotor has passed the lower dead position shown in Fig. 4. Thus, the chambers 30 and 31 are connected so that the air which is left in chamber 31 after the output has taken place can be used. As soon as pressure compensation has taken place and the pressure in the chamber 30 is equal to the pressure in the chamber 31, which e.g. may occur in the position shown in Fig. 6, a one-way valve 33 prevents the air from flowing in the opposite direction when the pressure in the chamber 31 decreases at its expansion. The one-way valve 33 is positioned at the. end 37 of the conduit placed closest to the chamber 31. Moreover, there may be a second one-way valve 34 close to the second end 38 of the conduit close to the chamber 30 in order to prevent the pressure in the conduit 32 from increasing since the pressure in the chamber 30 now is successively increasing. Thus, the conduit 32 is only operating during the time the rotor moves from the positions according to Figs. 4 - 6. After the position according to Fig. 6, the pressure in the chamber 31 will thus be considerably lower than if the conduit had not been there. This means that the air in the chamber 31 does not any longer has a pressure which is considerably higher than the pressure in the chamber 35 in front thereof, which is in the suction stroke and has approximately atmospheric pressure. This means in turn that the pressure in the chamber 31 does not any longer to the • same extent as in a conventional compressor help the driving of the rotor, and thus there is required a greater power from the drive motor of the compressor. Moreover, the chamber 30 will enclose more air than in the normal case, which means that the resistance against compression will be greater and thus a higher power is required by the drive motor. This also means that the pressure in the chamber 30 will be higher in the position according to Fig. 4 and that the amount of air will be higher compared to if the conduit 32 was not there. Thus, according to the invention there has been provided a consider¬ able improvement of the compressure according to Fig. 1 with very simple means, viz. only the addition of conduit 32. It is favourable that the conduit opens in the position shown in Figs. 4 and 5 since the increase of pressure in the chamber 30 in this position still takes place relatively slow. It would also be possible to place the mouth higher, seen according to Fig. 4, since the one-way valve 34 effectively prevents the air from passing out to said conduit. However, if the pressure in the conduit 32 of any reason will be higher than in the chamber 30, the one-way valve 34 will open and allow input of air, which is the effect aimed at. Said conduit 32 simultaneously provides a second favourable effect. When the pressure is revealed in the chamber 31 and fed to the chamber 30, the one-way valves 20, '19 in the- outlet and inlet conduits ' 17, 16, respectively, will immediately be closed with a • distinct movement, which means that said pair of valves will operate simultaneously. Moreover, it is prevented that said one-way valves will occupy an intermediate position which possibly will allow a certain flow-back. Thus, said conduit 32 will provide the same operation as the hydraulic system according to Fig. 1, which thus will be unnecessary. Moreover, it is made possible that said valves can be constrmucted as simple one-way valves, which improves the safety. The one-way valves will achieve a sufficiently fast respond time due to the servo action provided by the conduit 32. At high speeds it is uncertain if the one-way valves 33, 34 are sufficiently fast for operating as intended. According to an alternative embodiment of the invention and for avoiding said problem, the mouth of the conduit 32 is adapted at the most low position of the stator as shown in Fig. 6 at 39. The second end 38 of the conduit is at the same position as previously. Moreover, the rotor is provided with a recess 42 at the periphery thereof having the shape shown in Fig. 6. The recess 42 is positioned centered between the vanes in order to be placed opposite to the mouth 39 « when the rotor is in the position having smallest volume according to Fig. 4. However, the recess may be offset from said middle position if desired. Said placement of the recess 42 means that the rotor normally will be immediately above the mouth 39 during the major portion of its movement and thus at least essentially closing said conduit 32. However, when the recess 42 will arrive opposite to the mouth 39, a flow path will be opened allowing the air to flow through said conduit 32. In other words, the rotor 14 itself will by means of said recess 42 operate as a valve which opens and closes the mouth of the conduit at suitable positions. As shown in Fig. 6, the recess 42 has a sharp edge 40 and a plane surface 41 so that the opening of the mouth 39 takes place at a distinct position determined by said edge 40 while the closing of the mouth takes place successively during a longer time period determined by the surface 41. In this way, the closing of the inlet and outlet valves 19 and 20 is facilitated since the opening of the valve 32 takes place abruptly. Said recess 42 may of cource have other suitable shapes, cf. e.g. Fig. 7. * Of cource, the recess 42 increases the .dead space of the chamber 31, but the improved operation according to the invention compensates said drawback. The recess extends only over that part of the rotor which is immediately above said mouth 39 in the axial direction, which means that the influence on the increase of the dead space will be much less than appears from Fig. 6. In Fig 6 it is suggested that the conduit may be provided with an accumulator 43 for air so that the pressure in said accumulator at equilibrium is essentially constant and is somewhere between the outlet pressure of the chamber 31 and the inlet pressure of chamber 30. Said accumulator should have a relatively large volume and is preferably used at high speeds in order to equalize the very short pressure pulses from the dead space. At low speeds, the construction shown in Fig. 4 is preferred. In this case, the conduit 32 should be as short as possible in order that the pressure from the chamber 31 shall reach the chamber 30 in the shortest time possible. At the same time, the cross-sectional area of the conduit should be dimensioned so that the volume of the conduit will be the smallest possible at the same time as the flow of air will not be prevented in an unnecessary amount. The mouths 37 - 39 should be aerodynamically shaped having a flared connection to the inner surface of the stator having rounded corners. Suitably, the mouth is narrow in the peripheral direction but extendeds in the longitudinal direction (slot shaped) and then passes to a circular cross-sectional shape. This shape is advantageous for preventing short circuit between the chambers 31 and 35 when the corresponding vane passes said mouth. The nozzle is suitably a so called de Laval nozzle. It is of course possible to omit the one-way valves 33 and 34 and still achieve the operation according to the invention. However, in this case there is a risk that the conduit 32 will decrease the compression in the chamber 30 when it is still connected to the mouth 38 by pressing back a portion of the air inside the conduit. The dimensions and connection of the conduit to each chamber may also be valid in dependence of the application, specifically in dependence of the speed at which the compressor is driven and which counterpressure that prevails. " At certain speeds it is possible to achieve resonance in the conduit 32, which may be used for making the conduit more efficient and possibly means that the one-way valves can be dispensed with. The mouth 38 may also be adapted opposite to the mouth 39 in Fig. 6, whereby the recesses in the rotor control the opening and closing of this mouth, which in this case is placed in the gable of the stator opposite to the periphery of the rotor as shown at 44 in Fig. 6. It is also possible to adapt the mouths 39 and 44 in each gable of the stator so that the conduit 32 extends diagonally from one able to the other gable. This makes it possible to provide the rotor with two sets of recesses, one adjacent each stator gable so that the opening and closing of the mouths of the conduits may be adapted to the intended application and may possibly be offset in relation to each other for compensating possible time losses in the conduit 32. Moreover, the recesses may have different lengths at each end of the conduit in order to be adapted to the flow conditions prevailing. Thus, it is realized that the above-mentioned shunt conduit makes possible to use the compressed air amount in the dead space, which means that a more efficient compressor has been provided. Experiments have also shown that the compressor according the the invention does not need as much cooling as a compressor according to previously known technique. It is also possible per se to connect the first mouth of the conduit to the pressure outlet of the compressor, especially if the above-mentioned accumulator is used, but in that case the favourable effect according to the invention of using the dead space is not achieved. In Fig. 10 there is shown another variant of the compressor according to the invention in cross section. The compressor 100 comprises as previously a stator 101 in the shape of a cylindric body provided with radial cooling fins 102, cf. Fig. 11. In the cylindric body there are tree blocks 103, 104, 105. The left block 103 and the right block 105 are essentially similar but mirror rever.sed in relation to each other and comprise each a radial bearing 106, 107 for the rotor 108. The radial bearings may be roll bearings or needle bearings etc. The rotor is supported by a through hollow axis 109, which extends over essentially the hole length of the cylindric body 101. The axis is at its left end closed by a cap 110, which is removable and locked by means of one or several radial lock screws 111. The cap supports a radial fan 112 positioned outside the cylindric body, which fan provides cooling air to the cooling fins 102 through a cap which is not shown. At the right end, the axis is provided with a coupling to the drive motor 113, which suitably is an electric motor, but of course can be an internal combustion engine or similar. The coupling of the axis 109 to the output axis 114 of the motor is provided by a sleeve 115 which is positioned outside the axis and is provided with several radially inwardly extending fins 116 which co-operate with the corresponding grooves 117 in the output axis 114. The fins 116 are provided with rubber packings 118, which make an elastic coupling between the sleeve 115 and the hollow axis 109 positioned inside thereof while the coupling between the output shaft 114 and the fins 116 is essentially stiff. Of course, the coupling between the output shaft 114 and the fins 116 may be elastic while the coupling between the hollow axis 109 and fins 116 may be stiff whereby the same operation is achieved. Between the hollow axis 109 and the output axis 114 there is a space 119 which allows air to flow inside the hollow axis 109 from the surrounding atmosphere through holes 120 in the cylindric body 102. Of course, the air may be provided to the hollow axis 109 from the other side through suitable holes in the cap 110. The space inside the cylindric body 10.1 is divided into two halves symmetric around the line 121. Thus, there is in reality two rotors 108 or sub-assemblies positioned on each side of the block 104 which is of production reasons. These rotors are identical and are interconnected by the hollow axis 109 for common movement and only one of the halves is closer described. In Fig. 12 there is shown a cross section through the rotor 108, from which appears that the rotor has four identical parts in which four vanes 122 are positioned in corresponding slits 123. The vanes do not extend radially but form an angle to the radius so that the vanes extend in the rotational- direction which is. well-known within the art per se. This positioning makes it possible to use vanes of synthetic resin bounded coal, whereby the problem with lubrication of the vanes may be avoided. Thus, vanes of syntetic resin bounded coal manufactured of Rekofa Wentzel GmbH u CoKG under number 9257 are used, which have shown to be stiff enough for resisting bending forces occurring and which makes possible to completely eliminate lubrication by oil, which is a considerable advantage, specifically in view of the fact that the exhausted compressed air must not any longer pass a separator for oil. Moreover, the exhausted air will be much cleaner. The vanes may be manufactured with a very great surface equality and is mounted in the compressor with a slightly too big dimension in the transversal direction. At the first rotation of the rotor, the vanes are immediately worn to the width of the compression chamber so that a minimal leakage takes place. Moreover, it appears from Fig. 12 that the rotor comprises four inlet channels 124 having relatively great diameters which open to the periphery of the rotor. The hollow axis 109 is provided with corresponding holes 125 and inside each hole there is an inlet valve 126 which comprises a spring steel membrane 127 attached to a ring 128, cf Fig. 15. Inside the ring 128 there is an inner hollow axis 129 provided with corresponding holes 130. The spring steel membrane 127 is sqeezed between the ring 128 and the outer block 131, which has a rounded rim 138 so that the spring steel does not bend against the sharp edge. In Fig. 13 it is further shown that the rotor is provided with four outlet channels 133, which are controlled by corresponding outlet valves 134. All valves are positioned in a valve assembly 135 shown more in details in Figs. 14 and 15. The space 138 is connected to the outlet of the compressor through several holes 141 in the outer hollow axis 137. These holes 141 pass to a ring shaped groove 142 in the middle block 104, cf Fig. 10, and further to the outlet 143. Thus, the whole valve assembly forms a compact unit 135 which fits closely in the shaft 109 as shown in Fig. 10. The axis 109 is provided with a stop shoulder 146, which maintains the valve assembly 135 between the shoulder and the cap 110 by 0-rings 147 and 148. Thus, it is realized that the valve assembly 135 is easily exchangeable by removing the cap 110. Since the valve assembly is positioned in the interior of the hollow axis it is a simple task to convert the present single-step compressor into a two-step compressor by exchanging the valve assembly into one that series-connects the two compressor parts or sub-assemblies on each side of line 121, cf. Fig. 10. The shunt conduit itself gives some kind of multi-stage compression but it would be more adequate to call the shunt conduit a kind of turbo changer. If the two compressor halves on each side of line 121 are series-connected, normally, the second stage operates at higher pressure and should have a smaller volume compared to the first stage as shown in Fig. 1. However, by providing the first stage with the shunt conduit according to the present invention, said first stage has an increased volume through-put which means that it looks like a stage having a greater volume. Such a two-stage compressor is schematically shown in Fig. 9. Such a conversion is very simple as stated above in that only different valve assemblies may be used. In Fig. 9 there is shown a compressor divided into two sub-assemblies according to Fig. 10. These sub-assemblies are shown schematically in Fig. 9 and includes a common valve assembly 161 connecting the two sub-assemblies 162 and 163 in series as shown by arrows 164. A shunt conduit 165 is connected to the first sub-assembly 162 in the gable thereof. This conversion is made possible since the valve assembly is positioned in the hollow axis and since the shunt conduit provides said increase of volume through-put. From the description above, the operation of the compressor should clearly appear. Preferably, the compressor is dimensioned for being driven at a constant predetermined speed, e.g. 3000 r/m, whereby the spring forces in the spring steel membranes 127 and 139 are adjusted so that the centrifugal forces at said speed are balanced. Thus, the valves may perform their function at very small pressure differences over the valves, which is necessary at said high speeds. Of course the vanes can be made in one piece of material. According to another embodiment of the invention each vane 47 is divided into two halves by an inclined radially extending division line 160 as shown in Fig. 8. The sealing between the two halves takes place by making the abutting surfaces as smooth as possible. The centrifugal forces push each vane half outwards, which means that a lateral force is developed in the contact surface which aids in the sealing. Moreover, each vane half is biased by said centrifugal forces towards its gable and ensures a good sealing therebetween. The inclination of the division line 160 may be selected in dependence of the application area and materials used. At present it is preferred to have the division line having only a slight angle in relation to the radius and the two halves being identical. However, an offset of the division line may be advantageous at certain applications. In Figs. 17 - 19 there is shown an alternative valve assembly according to the invention having valve membranes which are completely unaffected by the centrifugal forces. The valve assembly comprises, as shown in Fig. 17, an input valve seat 174, an input membrane 172 and springs 178 urging said membrane towards the seat. The springs 178 are positioned in an input spring body 175. The input of air is shown by the arrow 171. The input valve seat is composed of a plurality of openings 181 as shown in Fig. 12. Fig. 19 shown the input membrane 172 and the openings for the springs 178. The output valve is shown to the right in Fig. 17 and comprises an output valve seat 176, an output membrane 173 and springs 179 positioned in an output spring body 177. The various bodies are sealed by 0-rings 180 where necessary. The operation should be clear to a skilled person. TAhe valve assembly shown is made for series connection of two or more sub-assemblies but a parallel connection would be obvious to a skilled person. As shown by broken lines in Fig. 10, each outer block 103 and 105 is provided with a shunt conduit 151 according to the invention. Said shunt conduit connects the compression chamber having its greatest volume with the diametrically opposite chamber having its smallest volume. The operation is exactly the same as described above in connection with Figs. 2 - 7. Alternatively, it is possible to arrange said shunt conduit in the rotor as shown in Fig. 16. The rotor is provided with a ring- -shaped channel 152 which is positioned around the axis 109 and of cource at axial distance from the inlet and outlet channels 124 and 133, e.g. outside the outer hollow axis 137. Four radial bores 153 extend from each compression chamber to the ring-shaped channel 152. The radial bores pass through the vanes, each vane being provided with a corresponding recess 154, which may be oval or rectangular. The opening 154 is placed and dimensioned so that it opens the corresponding bore 153 when the corresponding compression chamber has its smallest volume and thus the outlet stroke is completed as shown at the right bottom in Fig. 16 at the vane 156. Thence, the compressed air from the dead space is fed to the ring-shaped channel 152. After a rotation of about 20 , the opening 153 is closed by the fact that the vane now has moved upwardly as shown in the upper right position in Fig. 16. In the opening 154 there is an insert 155 which is movable between two positions in said opening 154. Said insert 155 has a slightly bigger thickness than the vane and thus has a higher friction against the walls of the rotor in relation to the vane. When the vane 157 in its upper position changes its movement direction from outwards to inwards, the insert will, due to the friction against the walls of the slit, be moved outwards in relation to the vane towards the tip of the vane to its second position shown in the left upper position in Fig. 16. Both gravitation forces and centrifugal forces co-operate to said relative movement. Thus, the corresponding opening 153 in the upper left position of the vane 158 is opened when the volume in the corresponding compression chamber is at its maximum and the compressed air in the ring-shaped channel can pass out to said compression chamber and increase the amount of air therein. After about 20 the opening 153 is closed again in order to prevent the successively compressed air from flowing back to the ring channel 152. When finally the vane 159 reaches ' its lower position, the movement direction of the vane is reversed and the insert change position again to that shown in the right lower position at the vane 156. Thus, the ring channel 152 will operate as a reservoar or accumulator for superfluous compressed air from the dead space and feed said compressed air into the compression chamber at that position where it may be reused in a useful way according to the present invention. By adapting the shunt conduit in the rotor, the advantage is achieved that the length of the shunt conduit is decreased and that the number of interferencies in the surface of the stator is minimized, which entails an improved operation. If necessary, the vanes may be provided with ears, which locally seals the hole 153 in the most extended position of the vane without the necessity to increase the length of the vane in its entirety. The shunt conduit described above in connection with Figs. 4 - 6, 10 and 16 may also be adapted for use in connection with other types of compressors such as piston compressors, screw compressors etc. For piston compressors there are needed at least two cylinders. For one-cylinder piston compressors the reservoir previously mentioned must be extended by a delaying device as positions for input and output do not occur simultanously. A skilled person realizes how the shunt conduit may be adapted to such compressor constructions. When the valves are adapted in the rotor as in the present invention, the dead space will increase due to the volume of the channels to said valves, especially if the output pressure is high and if more than four vanes, e.g. six or eight vanes are used. In this case it is essential to use the shunt conduit in order to compensate for the increase in the dead space of the compressor and substantially eliminate said drawback. Preferred embodiments of the invention has been described above for the purpose that a skilled person may understand and be able to use the invention. However, there are many possibilities of modification' of the embodiment described without departing from the inventive idea and the intention is that such modifications obvious to a skilled person should be included within the scope of the invention» The invention is only limited by the appended patent claims.

Claims: CLAIMS 1. A means at a compressor comprising at least one compression space and inlet and outlet channels for allowing input of air or gas to the compression space when an underpressure prevails therein in relation to the inlet pressure of the compressor and for output of air when an overpressure prevails therein in relation to the counterpressure of the compressor, c h a r a c t e r i z e d by a shunt conduit (32) which is adapted for connection of a first space (31) of the compressor having a small volume to a second space (30) of the compressor having a great volume for transferring the remaining amount of air having a high pressure from said first space to said second space. 2. A means according to claim 1, c h a r a c t e r i z e d in that the shunt conduit (32) connects a first chamber (31) of the compressor in the position thereof in which the output of air essentially has been terminated for transferring the remaining air having high pressure from said first chamber to a second chamber in the position thereof in which said second chamber essentially has terminated its suction stroke. 3. A means according to claim 1 or 2, whereby the compressor is a vane compressor comprising a stator (15) and an excentric rotor (14) positioned therein having vanes (47) defining several compression chambers (30, 31, 35, 36), and inlet and outlet valves (19, 20) or openings for allowing input of air or gas into each chamber in a position (30) thereof in which an underpressure prevails in relation to the suction pressure of the compressor and output of air or gas from each chamber in a position (31) thereof in which an overpressure prevails in relation to the counterpressure of the compressor, c h a r a c t e r i z e d in that the shunt conduit (32) is adapted to connect a first chamber (31) of the compressor with an essentially diametrically opposite second chamber (30) of the compressor in the position of the first chamber where the output of gas essentially has terminated for transferring the remaining gas having a high pressure to the second chamber in the position thereof in which it essentially has terminated its suction stroke. 4. A means according to claim 3, c h a r a c t e r i z e d in that the shunt conduit (32) is adapted in the stator and extends from a first position (37) of the stator which substantially corresponds to the position of the front vane of the corresponding first chamber (31) being in its position with the smallest volume, and to a second position (38) of the stator substantially diametrically opposite thereto which substantially corresponds to the position of the front vane of the corresponding second chamber (30) being in its position with the greatest volume. 5. A means according to claim 4, c h a r a c t e r i z e d in that the conduit (32) is provided with at least one one-way valve (33) at the mouth to said first position and/or at least one one-way valve (34) at the mouth to said second position. 6. A means according to claim 3, c h a r a c t e r i z e d in that the shunt conduit (32) is adapted in the stator and extends from a first position (39) on the stator which is between the vanes of the first chamber (31) when it is in its position with smallest volume, and to a second position (38) on the stator which substantially corresponds to the position of the front vane of the corresponding chamber (30) being in its position with the greatest volume. 7. A means according to claim 6, c h a r a c t e r i z e d in that the rotor (14) is provided with recesses (40, 41, 42) between the vanes, which recesses act as valves for the first mouth (39) and/or for the second mouth (44) of the shunt conduit. 8. A means according to any of claims 3 - 7, c h a r a c ¬ t e r i z e d in that the shunt conduit (151) is adapted in the gable (1+5) or gables of the stator and that the shunt conduit is placed in the cylindric housing of the stator. 9. A means according to claim 3, c h a r a c t e r i z e d in that the shunt conduit (152, 153) is adapted in the rotor and comprises valves adapted to open and close the shunt conduit. 10. A means according to claim 9, c h a r a c t e r i z e d in that the shunt conduit comprises a ring-shaped channel (152) adapted in the rotor and connected with each compression chamber through separate bores (153), including valves (154, 155) adapted to open and close for controlling the flow into the ring-shaped channel and the flow out from the ring-shaped channel, respectively. 11. A means according to claim . 10, c h a r a c t e r i z e d in that said valves are openings in each vane (154), which openings comprises inserts (155) which are movable-. 12. A means according to claim 3, c h a r a c t e r i z e d in that the compressor is divided into at least two substantially equal sub-assemblies (162, 163) which are mounted on a common axis and includes a common valve assembly (161) mounted in said axis, said valve assembly being exchangable between a first valve assembly connecting said sub-assemblies essentially in parallel and a second valve assembly connecting said sub-assemblies essentially in series. 13. A means according to claim 12, c h a r a c t e r i z e d in that said sub-assemblies are connected in series and that the first sub-assembly (162) is provided with said shunt conduit (165) in order to increase the volume through-put in said first sub- -assembly.

Inventors: DRAAISMA RUDOLPH, REICHMANN WERNER, DRAAISMA, RUDOLPH, REICHMANN, WERNER
Applicants: DRAAISMA RUDOLPH, REICHMANN WERNER, DRAAISMA, RUDOLPH, REICHMANN, WERNER
Application year: 1986
Main classification: F04C29
IPC codes: F04C18, F04C28, F04C29