DE2835826A1 - ROTARY PISTON COMPRESSORS WITH COOPERATING ROTORS - Google Patents

Description

PATENT ADVOCATES A. GRÜNECKER

2 O 3 Ό Ό £. D.

H. KtNKELDEY VV. STOCKMAtR

DR-INGL-A «ElCAtIK> fr

K. SCHUMANN

P. H. JAKOB

OFt-INS.

G. BEZOLD

CFtRFAWIC-OlPL-CHBtI

8 MUNICH

MAXIMUM CUP

Rotary piston compressor with interacting rotors

The present invention relates to a rotary piston compressor, the interacting runner comprises, namely a pressure runner and a suction runner, each of which have an essentially cylindrical body, and at least one blade or tooth extending from the circumference of the body and in the longitudinal direction of the Runner extends, each blade or tooth is adapted to with a corresponding recess in the cylindrical body of the other rotor and during part of its path of movement for sealing engagement with the inner surface of one common to the two runners Housing to engage with the runner inside

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TELEPHONE (OBS) 23 28 62 TELEX OS-29 38O TELEGRAMS MONAPAT TELECOPER

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of the housing are arranged so that their cylindrical Bodies are juxtaposed at a common generatrix, and wherein the housing has an inlet port and an outlet port specifies.

In the case of a rotary lobe compressor of the type mentioned above The cylindrical runners "roll" on each other, although a small space is usually formed between them is, and the blades or teeth are arranged such that the blade of a rotor on the engagement, area of the rotor arrives in front of the blade of the other rotor in such a way that each blade seals, but with some play in engagement with the corresponding Recess in the other runner will occur. In this way, there is space taken up by the cylindrical walls and the end walls of the compressor housing and limited by the rotors, divided into a suction chamber and a compression chamber, wherein the blades of the runners act as pistons, which during the rotation of the runners continuously the Reduce the compression space and increase the suction space until the blades reach the area of engagement of the runners. Afterward the compression of air or gas that is sucked into Uj in the above-mentioned suction chamber is initiated, while another amount of gas is sucked into another suction space that is being formed.

A rotary lobe compressor 'of the type mentioned above, it is now used as a heat pump or for more conventional purposes, several advantages compared to compressors of the type having oscillating pistons. Thus the Rotary piston compressor has only a few moving parts that can be fully balanced. It can also be used in rotary lobe compressors a sufficient seal usually without direct mutual contact between the .. Runners and can be achieved without direct contact between runners and the surrounding housing. As a result

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only the rotor bearings need to be lubricated, and wear, and maintenance can only be extremely low.

The suction chamber and the compression chamber, into which the inner cavity of the housing is divided by the rotor, can at least in certain angular positions of the rotor with the inlet or outlet opening of the compressor housing in connection stand. In a known rotary piston compressor, the outlet opening and possibly also the inlet opening are of the compressor housing a slot that is in a End wall of the compressor housing is limited and is formed as an arc of a circle «The end surfaces of the cylindrical Body of the runners cooperate with these curved slots in such a way that during the rotation of the Runner, the slots are only covered or opened when they hit the recess of the corresponding Runner are aligned. As a result, the runners not only work as pistons, but also as inlet and outlet ports. Exhaust valves; and the use of delicate valves of the type found on reciprocating piston compressors is avoided.

To get a compressor with as large a capacity as possible in relation to the external dimensions of the compressor achieve, it is desirable to have the blades or teeth with the greatest possible radial height with respect to the radius of the to form the cylindrical body of the runner. As a result, the cylindrical runners with relatively small Diameters formed. This, in turn, entails that the curved inlet and outlet slots in the end walls of the compressor housing are limited, can only have a fairly limited radial width and must be arranged at a relatively small radial distance from the rotor axis, at this point the peripheral speed of the rotor and consequently the speed at which the inlet and outlet slots opened and closed is relatively small.

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The greatest circumferential length of the curved slots that can be covered at the same time is determined by the circumferential width the recess in the cylindrical body of the corresponding rotor is determined. This width of the Recess is in turn determined by the width or thickness of the blades or teeth, which - among other things in order to reduce the centrifugal forces acting on it to a minimum - desirably as small as possible should be held. For the reasons mentioned above, the flow resistance of the known rotary lobe compressors, those described above> will be quite high, and consequently their efficiency will be relatively low, and this is especially true for compressors with high Capacity to rotate at high speeds. These unfavorable conditions can to some extent be improved by forming an outlet slot at both ends of the pressure runner and possibly also an inlet slot at both ends of the suction runner. In this case, however, it will be necessary to use the two outlet slots and the two inlet slots to connect to each other by means of external piping, which are relatively bulky, especially in the case of a Compressor with high capacity, which at a relatively low compression pressure works "

From GB-PS 665 484 a rotary piston compressor is known in which the runners are hollow, and in which the inlet and Outlet openings in the housing with the recesses of the suction runner or pressure runner via the cavity of the runner stay in contact. The openings that connect the inner cavities of the runners with the corresponding recesses, can then extend over the entire length of the recesses and have a circumferential width that is essentially the same as the width of the corresponding recesses. In order to achieve that the compression chamber of the compressor is only connected to the outlet opening reaches when the pressure in the compression room

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is substantially equal to or equal to a back pressure exceeds, a stationary slide valve body is arranged in the pressure runner of the last-mentioned, known structure, to the connection between the inner cavity of the pressure rotor and its recess and consequently also the Interrupt the compression chamber until the desired pressure is reached in the compression chamber was achieved. This creates a compression period followed by a blow-out period, will. In said British patent it is proposed that the pressure runner be fixed to a rotatable mounted shaft and herewith in the axial direction up to the blade and the recess of the pressure rotor addition is connected. The stationary slide valve can then be attached to the compressor housing. As in the said Patent is established, this structure has the disadvantage that it is only for relatively short runners is suitable, which therefore limits the achievable capacity to a sensitive extent.

The rotary lobe compressor according to the invention belongs to the one before mentioned type, so a type in which the outlet opening with the recess of the pressure rotor via an inner Is cavity in communication, which is formed in the cylindrical body of the pressure runner, the cavity a having stationary slide valve body which is adapted to the connection between the inner cavity and to interrupt the recess of the pressure runner during a predetermined angle of rotation range in order to achieve a To provide a compression period and to re-establish the connection during a subsequent rotation angle range, to provide a blow-out period. The compressor according to the invention is characterized in that the Connection between the inner cavity and the recess of the pressure rotor and the corresponding slide valve body extends only over part of the axial length of the recess at one or both ends thereof, the Pressure rotor on a corresponding rotor shaft along the

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remaining part of the axial length of the pressure rotor is mounted or supported, and in that an additional outlet opening in the end wall of the compressor housing between the outer surface of the slide valve body and the circumference of the cylindrical body of the
Pressure runner is attached.

When the compressor according to the invention, it is possible to have a good to achieve general support of even relatively long runners with a large capacity “Furthermore, the reduction the connection opening between the inner cavity and the recess of the pressure runner according to the invention because of the possibility of axial delivery through the additional Outlet opening to be compensated, which is limited in the end wall of the compressor. It turned out that due to the aforementioned connection of radial and axial discharge, particularly good discharge flow conditions can be achieved during the entire delivery period, since the said cooperation is a relatively quick opening as well as a relatively quick one Closing the outlet openings caused so that the actual Compression diagram of the compressor can be approximated to the theoretical diagram, which means that the efficiency of the compressor will be particularly good.

The slide valve body is preferably formed in two parts / with each part extending in the axial direction from a corresponding end of the pressure runner, and with the part totaling one half to two thirds
covers the axial length of the pressure rotor. Said parts of the sliding valve body preferably have an outer diameter such that the tip of the suction rotor blade just touches the valve body parts (with a certain amount of play) when it runs past the parts.

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The front surface of the recess in the pressure runner is preferably formed essentially as part of a concave cylindrical surface which has a radius, which is greater than the radial distance from the center of the distance between the axes of the two runners to the radially outermost part of the suction rotor blade, the called cylindrical surface touches the outer surface of the slide valve body (with a certain amount of play). By forming the cooperating front surfaces of the pressure runner recess and the suction runner blade in particular, good engagement conditions achieved by means of simple and easily machinable surface shapes. if the cylindrical body of the suction or pressure rotor have the same diameter, the said radial Distance must be equal to the radial height of the suction rotor blade, and in this case the radius is the concave The cylinder surface is preferably greater than the said blade height.

The front surface of the blade or the tooth of the suction runner preferably has a convex shape in order to to sealingly engage the concave front surface of the pressure runner recess. If the said If the concave surface of the pressure runner recess is a cylinder surface, as mentioned above, then the convex surface will also be Surface approximately be a cylindrical surface tangential to the outermost part of the suction rotor blade transforms. If the radius of the concave cylinder surface of the pressure runner recess is equal to the said radial Distance, then the convex cylinder surface of the suction rotor blade would have to have the same radius. In this In this case, however, the two cylinder surfaces would interact in such a way that the free flow of air or gas in the expanding space, which is limited in the pressure rotor recess, if the suction rotor blade is with their movement out of engagement with this recess begins, would be counteracted. The larger the radius of the

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concave cylinder surface of the pressure runner recess is chosen, the more freely air or gas can flow into the expanding space, but at the same time becomes increases the size of the recess and the blade, making it more difficult to balance the runners and the Effectiveness of the achievable seal or seal between the front surfaces of the pressure runner recess and suction impeller during the later stage of the blowdown period is decreased. According to the invention the cylindrical surface of the pressure runner recess can have a radius which is 1.25 times the radial Distance is; this has proven to be a good compromise given the above circumstances. The above mentioned rapid opening and closing of the outlet openings depends on the circumferential speed of the pressure runner. This peripheral speed and consequently the speed of opening and closing can, however can be increased in a manner known per se by using a pressure runner which has a cylindrical Has body with an outer diameter which is greater than the distance between the axes of the runners. If the The outer diameter of the cylindrical body of the pressure rotor is greater than the distance between the rotor axes, then the diameter of the suction rotor will be correspondingly smaller, and the part of the cylindrical Body of the pressure runner, which is radially outside an ima- Ginary cylinder surface is coaxial with the pressure runner and has a radius that is equal half the distance between the rotor axes will act as a tooth in relation to the suction rotor. The engagement between the radially outer part of the front surface of the pressure runner recess and the portion of the front surface of the suction rotor blade that is closer to the axis of the suction rotor than half the distance between the rotor axes can be achieved using the same principle as described above in connection with the convex front surface of the suction rotor blade and the concave cylindrical

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drical front surface of the cooperating with it Druckläuferausnehinung is described. I.e. that the concave transition surface between the outer surface of the cylindrical body of the suction runner and the front Surface of the suction rotor blade is preferably shaped as a concave cylindrical surface which has a radius which is greater than the difference between half the distance between the rotor axes and the radius of the outer surface of the cylindrical Body of the suction runner, with the cylindrical .. surface in adjacent surfaces of the suction runner transforms.

Since the rear surface of the suction impeller is constantly adjoins the suction chamber or the suction chamber of the compressor housing, it can be shaped so that it is the smallest possible Resistance to the gas flow into the suction rotor recess offers when it is with this recess intervenes. Thus, the pressure rotor blade can be shaped so that only the front part, for example a quarter of the circumferential length of the blade is adjacent to the inner wall of the housing. This is sufficient to get the to achieve the desired seal against the inner wall of the housing, and the disturbance formed by the blade the gas flow into the suction rotor recess is reduced. Furthermore, a sufficiently long circumferential length of the Blade or tooth root obtained in order to effectively attach the blade to the cylindrical body of the Ensure the runner.

When the compressor according to the invention are particularly good Inlet and outlet flow conditions achieved so that the Relationship between the radial height of the blade or the tooth and the total rotor diameter can be increased can, wherein the efficiency of the compressor is increased even further because of the pressure loss due to a margin can be that between the radially outer surfaces

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the rotor blades and the adjacent inner walls of the surrounding housing and between the alternately interacting rotors is of less importance if the capacity of the compressor is using a greater radial height of the blades is increased.

It should be noted that the term "intervention" or "touch" as used in the present description and in the claims, including the non-contact Engagement includes, i.e. the state in which there is a gap between the cooperating or one within the other engaging parts.

A particular aspect of the invention resides in a rotary piston compressor which is of two hollow, cooperating nature Has runners, each having a blade or a tooth and a corresponding recess, which is in communication with the cavity of the rotor. A slide valve body that is part of a cylinder forms, one of the runners is stationarily mounted inside the cavity, namely in the pressure runner, around the discharge opening of the compressor during a compression period to close and open the outlet during a blowdown period. According to the invention extends the Slide valve body only over a fraction of the axial length of the recess at one or both ends thereof, and the pressure rotor is on a corresponding rotor shaft mounted or supported along the remaining part of the axial length of the pressure runner. There is also an additional Outlet opening in the end wall of the compressor housing and is limited by the .Endfläche of the pressure rotor controlled, the discharge flow conditions of the compressor are greatly improved.

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ORIGINAL INSPECTED

The invention will now be described with reference to the accompanying drawings Drawings described in more detail, wherein

Fig. 1 is a schematic view of a section Embodiment of the compressor according to the invention shows, in the direction of the arrows I-I seen in Fig. 2,

Fig. 2 is a sectional view as indicated by arrows II-II in Fig. 1;

Fig. 3 is an even more schematic view of a

'■■.'.:. -LliSchnitts. '. And shows a pressure runner and the recess formed in it,

Figures 4 and 5

each is a view of a section corresponding to that shown in Fig. 2, but with the runners in different turning positions.

The rotary piston compressor shown in the drawing has a housing 10 which has an interior space which is limited by a wall 11, which is essentially how .the number 8 is formed and two cylindrical obex ~ - has surfaces that have parallel axes. A runner 12 (hereinafter referred to as "pressure runner") with an inner Exhaust duct and a rotor 13 (hereinafter referred to as "suction rotor") with an inner inlet duct are within the Housing 10 and mounted coaxially with its inner cylinder surfaces. Each of the runners essentially comprises one cylindrical body 14 and 15, which are in proportion have such a diameter in relation to their spacing that these bodies are connected to one another along a generatrix are in engagement or touch each other (see in particular Fig. 2). On each of the cylindrical runners 14 and 15 is a shovel or a tooth 16 or 17 attached, the has a shape which will be described in more detail below. The runners 12 and 13 comprise radial ones

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Arms or spokes 18 and 19, by means of which the runners are attached to rotor shafts 20 and 21, which are rotatably mounted in the housing 10 by means of bearings 22 and 23. The rotor shaft 21 merges in an extension into a drive shaft 24, and the rotor shafts are with one another connected by identical, intermeshing gears 25 and 26, which ensure that the runners 12 and 13 constantly at the same speed and in opposite directions Rotate direction as indicated by arrows in Figs. The cylindrical bodies 14 and

15 of the runners are hollow and the inner cavity of the cylindrical body 14 of the pressure runners communicates partly with an outlet opening 27 " which is defined in the end cover of the housing 10" as shown in Fig. 1, and partly via outlet openings 28 at Bottom of an elongated depression or recess 29 formed in the pressure runner 12, a space being formed which is shaped like the numeral 8 and is defined between the wall 11 of the housing and the cylindrical bodies 14 and 15. The interior of the suction rotor 13 is similarly partially in connection with an inlet opening 30, which is delimited in the end cover of the housing, and partially with the space in the housing _t which is shaped like the number 8, via an axial opening or a slot 31, which extends essentially along the entire axial length of the suction rotor and forms a recess 32 therein. Each of the recesses 29 and 32 is shaped so that they the blade or the tooth

16 or 17 of the other runner during the counter-rotating Can accommodate rotary movement of the runner.

In operation of the compressor, the cylindrical top surfaces of the blades or teeth 16 and 17 move sealingly along the wall 11 of the rotor housing during the main partly the rotor movement, and at the same time the cylindrical bodies 14 and 15 of the rotor lie along a Generating close together. The housing

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space shaped like the number 8 / into a suction chamber or a suction chamber 33 divided, which is in communication with the inlet opening 30 and an increasing one Has volume, as well as in a compression chamber or a compression space 34, which is a decreasing Has volume (see Fig. 2) and with the outlet port 27 in communication during part of the compression movement as explained below. Thus the blades or teeth 16 and 17 act as movable ones Piston in the space shaped like the number 8.

As shown in Fig. 1, the spokes or arms 18 of the pressure runner 12 are only along the central portion of the Shaft connected to the rotor shaft 20. Slide valve body 35, which are designed as cylinder sectors, are stationarily attached to the end walls of the housing 10 and extending axially inward therefrom. This slide valve body cooperate with the outlet openings 28 which delimit the recess 29 of the pressure rotor 12 at the bottom are, and these openings 28 can also only be found at the end sections of the rotor and have a axial length which corresponds to the axial length of the slide valve body 35. This slide valve body 35 are set up to close off the outlet openings 28 during each compression period in such a way that the compression in the compression chamber 34 essentially can take place adiabatically until a pressure is reached that is substantially equal to or greater than the counter pressure, against which the compressor is working. The output period follows this adiabatic compression. Around improved outlet flow conditions for the compressed Gas or the compressed air during the dispensing period, and a quicker opening and a quicker one Closing the compression chamber 34 to achieve is one additional outlet opening 36 formed in each end wall of the housing. These outlet openings 3 6 are with the outlet openings 27 in connection and are shaped such that

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they usually from the end walls of the cylindrical Body 14 exposed and. be locked, but they are attached and opened when the pressure runner recess 29 assumes an angular position in which it is on the opening 36 is aligned. The outlet flow conditions for compressed gas or compressed air can be improved by increasing the radial width of the gas outlet opening 36. Such an increase the radial width can be achieved by using a pressure runner 12 which is cylindrical Body 14 with an approximately larger diameter than that of the cylindrical body 15 of the suction rotor 13 as shown in the drawings.

Figures 4 and 5 represent the final stages of the output period which is critical for the efficiency of the compressor. In this position. The compression area ■ 34 essentially through the end walls of the housing, the blades 13 and 14 and through the surfaces of the recess 29 limited. The compression chamber is up to the last moment with the gas outlet opening 27, which is in the End cover of the housing 10 is formed over the openings 28 in connection, which increasingly from the slide valve bodies 35 are closed, as well as via the gas outlet openings 36, which increasingly from the cylindrical body of the pressure runner are covered. In favor of the efficiency of the compressor, it is essential that the compression space 34 is reduced to zero essentially at the moment in which the openings 28 and 36 are completely closed, so that no "dead space" is is of practical importance. In the embodiment shown in the drawings, this becomes the case achieved that the suction rotor blade 17 with the pressure rotor blade 16 and! the surfaces of the recess is engaged such that when the runners are rotated the lines of contact are moved toward one another and meet at the axial line where the open

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openings 28 and 36 covered at the latest by the slide valve bodies or the cylindrical body 14 of the pressure rotor and are locked.

In the embodiment shown in the drawings, between the rear (calculated in the direction of rotation) Edge 37 of the suction rotor blade 17 moving along a circular path ":" and the front surface the pressure rotor blade 16 and the adjacent one the rear surface of the print run recess achieved a line of contact, these surfaces being shaped as cycloids. This line of contact moves in the direction of rotation together with the rear edge 37. The other line of contact is between the front surface 39 of the suction runner vane 17 and the front surface 40 of the pressure runner recess 29 scored. In the embodiment shown in the drawings, the surface 40 is part formed a concave cylinder surface which tangentially touches an imaginary cylinder surface 41, which is a continuation the cylindrical slide valve body 35 forms, and as shown in FIG. 3, the surface 40 has preferably a radius 42 which is a little larger than the radial distance 43 between the imaginary cylinder surface 41 and a circle 44 with its center '-. On der.-axis of the pressure runner is seated and has a radius that is equal to half the distance between the runner axes. This circle can be viewed as the pitch circle of the gear 25, and the corresponding pitch circle of the gear 26 on the suction rotor shaft is denoted by 45. The front surface 39 of the suction rotor blade, which is connected to the Surface 40 interacts is formed as a corresponding convex surface which is designed to be in to come into sealing engagement with the cylinder surface 40, and which is also approximately a cylinder surface, which merges into the radially outer, cylindrical, uppermost surface of the blade or tooth and has a radius, which is greater than the radial distance from the part

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circle 45 of the suction runner to the top surface of the Suction rotor blade. As indicated in FIGS. 4 and 5, this shape of the surfaces 39 makes it possible and 40 achieved that the line of contact between the Surfaces opposite to the direction of rotation of the rotor moved as desired.

When the cylindrical body 14 of the pressure runner a has a larger diameter than the cylindrical body 15 of the suction runner, as mentioned above, then the edge acts 46 between the outer surface of the cylindrical body 14 and the front surface 40 of the pusher recess as a tooth or blade which, as shown in Fig. 4, engages with a corner 47 which defines the transition The corner 47 is then preferably formed between the cylindrical body 15 and the blade 17 of the suction runner designed as a concave cylindrical surface which has a radius that is greater than the radial distance between the outer surface of the cylindrical body 15 and the pitch circle 45 of the suction runner, and the edge 46 can then v ^ i:.: have a corresponding convex curvature.

It should be noted that various changes and modifications to the embodiment shown in the drawings can be made within the scope of the present invention. Thus, the interacting surfaces of the blades and recesses do not necessarily have the shapes described, provided that other precautions are taken to ensure that the lines of contact are aligned to be moved to reduce the dead space to a minimum. It should also be noted that although the measures mentioned above, namely the reduction of the dead space, the improvement of the outlet flow conditions from the pressure rotor and the advantageous. Attachment of the Slide valve body all work together to make a rotary lobe compressor that is a particularly good one

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Has efficiency, these measures, also advantageously Can be used on its own without using the other.

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Claims (6)

PAVrNlANWyS LFE "A. GRUNECKER H. KINKELDEY DR-IWL OR-ING. AeE (CALTEd-O K. SCHUMANN DR RER NAX. - DIPL.-PHYS. P. H. JAKOB G. BEZOLD Often. RSl NAT.- DPL-CHEM 8 MUNICH MAXlMlLtANSTRASSE 16 Aug 1978 EH 13 Aktieselskabet Thomas Ths. Sabroe & Co. Chr. D. X's Yej 201, DK-8270 Back to s ρ Rotary piston compressor with interacting rotors, namely a pressure rotor and a suction rotor, each have a substantially cylindrical body and at least one blade or tooth that extends from the circumference and in the longitudinal direction of the rotor extends, each blade or tooth is adapted to have an associated recess in the cylindrical Body of the other runner ~ and with the inner surface during part of its path of movement a housing common to the two runners to enter into sealing engagement, the runners inside of the housing are arranged in such a way that their cylindrical bodies abut one another along a common generatrix, the housing defining an inlet opening and an outlet opening which in turn correspond to the recess of the pressure runner is in communication via an inner cavity formed in the cylindrical body of the pressure runner and wherein the cavity includes a stationary slide valve body adapted to 909812/0702 TELEPHONE (088) 922882 TELEX 06-2SSSO TELEGRAMME MONAPAT TELEKOPlEREFi the connection between the inner cavity and the recess of the pressure runner during a predetermined To interrupt the angle of rotation range in order to achieve a compression period, and the connection during a to restore the subsequent angle of rotation range in order to achieve a blow-out period, thereby g e k e η η ζ E ichnet that the connection (28) between the inner cavity and the recess (29) of the pressure runner (12) as well as the corresponding. Slide valve body (35) itself extends only over part of the axial length of the recess at its one or both ends that the Pressure runner on a corresponding runner shaft (20) along the remaining part of the axial length of the pressure runner attached or mounted, and that an additional outlet opening (3 6) in the end wall of the compressor housing between the outer surface (41) of the slide valve body and the circumference of the cylindrical body (14) of the pressure runner is formed. 2. Rotary piston compressor according to claim 1, characterized in that that the slide valve body (35) is in two parts, each part axially extending from a corresponding one End of the pressure runner (12) extends out and the parts Cover a total of half to two thirds of the axial length of the pressure rotor. 3. Rotary piston compressor according to one of claims 1 or 2, characterized in that the front surface (40) of the pressure runner recess substantially as part of a concave cylindrical surface is formed which has a radius (42) which is greater than the radial distance (43) from the center of the distance between the axes of the two runners to the radially outermost part of the suction rotor blade (17), and that the cylinder surface is the outer Surface of the slide valve body (35). 909812/0702 2835828 4. Rotary piston compressor according to claim 3, characterized in that that the cylindrical surface (40) of the pressure runner recess (29) has a radius that is approximately 1.25 times the radial distance (43). 5. Rotary piston compressor according to one of claims 1 up to 4, whereby suction and pressure runners are set up to rotating at the same angular velocity and the cylindrical body of the pressure runner having a Has outer diameter which is greater than the center distance of the rotor, characterized in that the transition surface (47) between the outer surface of the cylindrical body (15) of the suction runner and the front The surface (39) of the suction rotor blade (17) is shaped as a concave cylindrical surface which has a radius, which is greater than the difference between half the distance between the rotor axes and the radius of the outer surface the cylindrical body of the suction rotor, 6. Rotary piston compressor according to one of claims 1 to 5, characterized in that the blade (16) of the pressure rotor rests sealingly against the inner surface (11) of the housing only at the front part of its circumferential length. 909812/0702