EP1640613A1 - Rotary piston compressor and process to use it - Google Patents

Abstract

The operating process is for a rotary piston compressor (1) with rotors (10, 20) to compressed gas. The gas-dynamic impact is created in a feed chamber (4) between its inflow side (4') and outflow side (4"). The closing time from the separation of the feed chamber from the volume enlargement region (V) is measured so that the filling of the feed chamber is increased by the impact charge.

Description

Technical area

The present invention relates to a rotary compressor for compressing gaseous media, comprising two wound rotors enclosed by a housing, each having at least three vanes for forming a number of delivery chambers between the vanes and the inner wall of the housing, and a method for operating such a rotary compressor.

State of the art

Rotary or Roots compressor of the type mentioned are long known and disclosed for example in DE 34 14 039 C2 or DE 31 14 064 C2. Due to increased demands, rotary piston compressors are now operated at high speeds, whereby the gas mass flow is increased accordingly. However, the increased speeds have the consequence that for each individual intake inevitably only a smaller amount of time is available. This has the disadvantageous effect of a poorer filling (lower degree of delivery) and thus a reduction in the per mass of rotation promoted gas mass. The increase in the mass flow of the compressible, gas or fluid Medium thus takes place only to a lesser extent than the increase in speed. This results in a limited or decreasing volumetric efficiency.

Presentation of the invention

It is therefore an object of the present invention to provide a rotary compressor of the aforementioned type and a method for operating a rotary compressor, which enables an increased delivery rate.

This object is achieved by a method having the features of claim 1 and by a rotary compressor with the features of claim 5. Advantageous developments of the invention are specified in the dependent claims.

The present invention is based on the idea to increase the degree of delivery of the rotary compressor in that generated in the respective delivery chamber, a fluid dynamic shock in the fluid to be compressed and used selectively. As a result, the filling in the respective delivery chamber is significantly increased and thus achieved a very good degree of delivery even at higher speeds. In this case, to achieve a pressure surge in known rotary compressors often only minor structural and / or operational adjustments or changes required, so that the principles of the present invention are economically applicable.

The generation of a pressure surge is carried out according to the invention by a flow through a delivery chamber with velocity component in the delivery chamber longitudinal direction and rapid separation of the respective delivery chamber from the area of increase in volume. This is for efficient use of the fluid dynamic shock generated thereby According to the invention provided that the inflow side of the respective delivery chamber is still open to the intake and only at a suitable time, but before a connection of the respective delivery chamber to the pressure side, is closed so that increases the filling of the delivery chamber by shock charging.

In other words, in the method according to the invention and the device according to the invention, a closing time from the separation of the relevant delivery chamber through which the delivery chamber extends is increased from the region of increase in volume until the relevant delivery chamber is closed on the inflow side in such a way that the filling of the delivery chamber is increased by impact charging becomes.
The advantages achieved by the invention are, in particular, that an improved delivery rate and a correspondingly increased volumetric efficiency are achieved by the targeted generation and use of a gas-dynamic impact. As a result, the speed range of rotary piston compressors is significantly increased because now high speeds can be used efficiently, which increases the overall management and improves the efficiency.

The term "gas-dynamic shock" refers to a phenomenon, as occurs for example in pipelines in a sudden closing of a slide upstream of the slide. This creates a pressure front, which moves approximately at the speed of sound upstream through the medium. This dynamic process adds another component to the static pressure in the medium, increasing the pressure and, for compressible media, the degree of filling.

According to a development of the method according to the invention, the operation of the rotary compressor by changing controlled geometric variables and / or the rotational speed of the rotary compressor, taking into account the temperature and the type of gaseous medium. The temperature and the nature of the gaseous medium determine the rate of propagation of a gas-dynamic impact within the medium and are therefore specifically taken into account in the operation of the rotary compressor according to the invention. The speed of the rotary compressor has an immediate effect on the closing time and the separation time to be discussed below and is therefore an important parameter in the operation of a rotary compressor according to the invention. The individual geometric parameters will be discussed in more detail below.

In order to ensure an effective generation of a gas-dynamic impact, according to a development of the present invention, it is provided that the rapid separation takes place within a separation time in which the rotors respectively pass through a rotation angle from the amount of the twisting angle and which is smaller than the 2.0.degree. Fache the duration of the gas-dynamic shock for the passage of the respective delivery chamber in Förderkammerlängsrichtung. In general, it should be noted that a progressive shortening of the separation time results in an increasingly pronounced gas-dynamic shock. Therefore, in view of the intended improvement in the degree of delivery in preferred embodiments, the separation time is to be gradually limited to 1.5 times, 1.0 times, 0.75 times and 0.5 times, respectively.

• 0,25 < t_S/t_L < 1,75;
• bevorzugt 0,50 < t_S/t_L < 1,50;
• besonders bevorzugt 0,75 < t_S/t_L < 1,25.

In addition to an effective generation of a pressure surge, according to the invention, however, it is also important that the pressure surge is also used efficiently for an increased filling of the relevant delivery chamber and thus for an increase in the delivery rate. For this purpose, it is provided according to a development of the present invention that the closing time is less than 1.75 times the running time. This will ensures that the pressure surge generated in the delivery chamber does not "fizzle out", whereby an optimal exploitation of the pressure surge is achieved when the closing time is approximately equal to the term. Accordingly, it is particularly preferred if the ratio between closing time and running time approaches as closely as possible a ratio of 1.0 and lies in the following ranges:

• 0.25 <t _S / t _L <1.75;
• preferably 0.50 <t _{S /} t _L <1.50;
• more preferably 0.75 <t _S / t _L <1.25.

In the generally defined in claim 5 rotary compressor according to the present invention, an inflow opening is preferably provided, which allows at least in phases an inflow, in conveying chamber longitudinal direction. The starting point of this preferred embodiment is the fact that the pressure surge generated in the relevant delivery chamber generates a suction effect. This suction effect is used according to the invention to increase the filling of the respective delivery chamber, wherein the medium required to increase the filling enters the relevant delivery chamber via the inflow opening.

According to one embodiment of the invention, the inflow opening is at least partially limited by a control edge, the shape of which preferably approximates that of a wing or tooth portion, which passes in advance during operation of the rotary compressor, the control edge. By this measure, the inflow of medium in the relevant delivery chamber can be precisely controlled in terms of time and volume, so that the degree of filling increases and a "fizzling" of the pressure surge can be prevented. The shape of the control edge does not have to correspond exactly to that of the wing or tooth portion, but can also be flattened and approach a linear shape.

With regard to a possible variable operation of the rotary compressor, it is also particularly preferred that the inflow has an adjustable geometry, and in particular the control edge is adjustable. By this measure, it is for example possible to adjust the inflow conditions at the inlet opening to the operating speed of the rotary compressor, the temperature or type of medium to be conveyed, etc., so as to ensure the efficiency and economy of the rotary piston connector in a wide speed range.

• Länge der jeweiligen Förderkammer (4) in Förderkammerlängsrichtung,
• Ausbildung und/oder Anordnung der Zuströmöffnung in die jeweilige Förderkammer (4),
• Verwindungswinkel (β) der Rotoren (10, 20),
• Anzahl (n) der Flügel bzw. Zähne (12, 14, 16, 22, 24, 26) pro Rotor.

The above-mentioned geometric influencing variables relate generally to the design of the components of the rotary compressor according to the invention. According to the invention, however, it is particularly preferred for the geometric influencing variables to comprise at least one or more of the following variables:

• Length of the respective delivery chamber (4) in delivery chamber longitudinal direction,
• Training and / or arrangement of the inflow opening in the respective delivery chamber (4),
• Twist angle (β) of the rotors (10, 20),
• Number (s) of blades or teeth (12, 14, 16, 22, 24, 26) per rotor.

Brief description of the drawings

Fig. 1

shows a schematic perspective view of two twisted rotors for a rotary compressor according to the invention;

Fig. 2

shows a schematic perspective view of a rotary compressor 1 as a preferred embodiment of the present invention;

Fig. 3 to 6

each show a schematic sectional view of the rotary compressor 1 shown in Figure 2 in different operating phases, wherein the section along the in Fig. 2 facing the viewer edge of the rotors 10 and 20 is guided.

Fig. 7

shows a schematic sectional view of a modified embodiment of the rotary compressor 1 in the operating phase according to FIG. 4.

Detailed description of preferred embodiments

Preferred embodiments of the invention will now be described in detail with reference to the accompanying drawings.

Fig. 1 shows a schematic perspective view of two twisted rotors 10, 20 for a rotary compressor according to the present invention. The rotors 10, 20 are equipped in the present embodiment, each with three blades or teeth 12, 14, 16, 22, 24, 26 and are arranged to mesh with each other. At their respective ends, the rotors 10, 20 have only indicated waves 18, 28, by means of which the rotors can be rotatably mounted and driven in a housing or the like. The rotors 10, 20 are wound around their longitudinal axis, wherein the degree of distortion can be given by an angle β, which indicates the twist angle between the respective ends of the rotors 10, 20. The twist angle β is 40 ° in the present embodiment, although the present invention is not limited thereto. Rather, the torsion angle β may in principle assume any desired values, as long as it does not become so large that a short circuit between the pressure side and the suction side results.

Fig. 2 shows a schematic perspective view of a rotary compressor 1 as a preferred embodiment of the present invention. The rotary piston compressor 1 shown in FIG. 2 contains the twisted rotors 10, 20 already described with reference to FIG. 1, which are enclosed by a housing 2 and are rotatably mounted therein via the shafts 18, 28. Between the wings or teeth 12, 14, 16, 22, 24, 26 of the rotors 10, 20 and an inner wall 2 'of the housing 2 conveying chambers 4 are formed, which are flowed through during the operation of the rotary compressor from a medium to be conveyed. It should be noted that during operation of the rotary compressor are continuously formed by two rotors 10, 20 delivery chambers and dissolved, but by way of example only one delivery chamber 4 is discussed below. Further, in the area between the rotors 10, 20, a region of volume increase V is formed, i. an area in which increases in a rotation of the rotors 10, 20, the volume between adjacent vanes and thereby feed medium is sucked.

The inflow of the pumped medium into the rotary compressor 1 takes place on an inflow side 4 'via inflow openings 30, which are provided in such a way that the inflow into the rotary compressor takes place at least partially axially. The inflow openings 30 are, as can be seen in Fig. 2, each bounded on one side by a control edge 32, whose shape corresponds to that of a wing section, the control edge 32 passes in advance during operation of the rotary compressor. Although in the present embodiment, a fixed control edge 32 is shown, the geometry of the control edge 32 can be adjustable in particular during operation of the rotary compressor 1.

During operation of the rotary compressor, the respective delivery chamber 4 is flowed through by the conveying medium in the longitudinal direction from an inflow side 4 'to an outlet side 4 ", i. in the direction from the viewer in Fig. 2 facing side to the side facing away from the viewer in Fig. 2. For clarity, the upstream ends of the vanes or teeth are designated 12 ', 14', 16 ', 22', 24 ', 26', while the opposite ends of the vanes are 12 ", 14". , 16 ", 22", 24 ", 26" (see also Fig. 1).

The operation of the rotary compressor 1 according to the invention will be described below in detail with reference to Figures 3 to 6, each showing a schematic sectional view of the rotary compressor shown in Fig. 2 in different phases of operation, the section along the in Fig. 2 facing the viewer edge of Rotors 10 and 20 is guided. In the individual views, the contours of the ends of the rotors 10, 12 facing the viewer are shown by solid lines, while the contours of the ends of the rotors 10, 20 facing away from the observer are shown by dashed lines.

Fig. 3 shows "Phase I", in which in the region of the increase in volume V delivery medium is sucked into the rotary compressor 1, which is to be ejected later on the pressure side in the region of an ejection opening A. The direction of rotation of the rotors 10, 20 is indicated by two arrows in Fig. 3 and the following Figs. the rotor 10 rotates counterclockwise while the rotor 20 rotates in the clockwise direction.

The beginning of the subsequent "Phase II" is shown schematically in FIG. Phase II is initiated by the fact that the delivery chamber 4, between the teeth 12, 14 of the Rotor 10 and the inner wall 2 'of the housing 2 is formed, is separated from the area of the increase in volume V. This separation takes place in that the rear end 14 "of the rotor tooth 14 is brought into abutment with the housing inner wall 2 'at the point indicated in FIG. 4 by a suction-side ridge angle fs, and thus the delivery chamber 4 from the area of the increase in volume V. As a result of the rapid separation of the delivery chamber 4 from the region of the increase in volume V, a gas-dynamic impact is generated in the delivery chamber 4 approximately at the time shown in FIG.

The separation of the delivery chamber 4 from the region of the increase in volume V takes place in a period of time in which the rotors 10, 20 each pass through a rotation angle of the amount of the torsion angle β, which thus decreases with increasing speed. The separation time can therefore be defined, for example, with purely axial inflow as follows: $${\mathrm{Separation\; time\; t}}_{\mathrm{T}}=\mathrm{Twist\; angle\; \beta }/(6*\mathrm{Speed\; n})\mathrm{,}$$

The generated in the delivery chamber 4, gas-dynamic shock now propagates in the delivery chamber 4 from the viewer facing away to the viewer side facing (inflow side), approximately at the speed of sound, in turn, depending on the temperature and the properties of the fluid stands.
A transit time t _L , which requires the gas dynamic shock to pass through the delivery chamber 4 in the delivery chamber longitudinal direction, is accordingly: $${\mathrm{Runtime\; t}}_{\mathrm{L}}=\mathrm{F}\ddot{\mathrm{O}}\mathrm{rderkammerl}\ddot{\mathrm{a}}\mathrm{nge}1/\mathrm{Speed\; of\; sound\; a}$$

During the further course of phase II, the delivery chamber 4 via the inflow opening 30 (see also Fig. 2) further connected to the inflow side, so that under the Effect of the gas-dynamic impact further medium enters the delivery chamber 4 and the filling of the delivery chamber 4 is continuously increased.

With the closing of the delivery chamber 4 on the upstream side of the beginning of "Phase III" is reached, which is shown in Fig. 5 schematically. At this time, the inflow-side end 14 'of the wing 14 has passed the control edge 32 so far that the inflow opening 30 is completely closed. The delivery chamber is now completely closed and is continued in the direction of rotation together with the sucked-in delivery medium in order to discharge the delivery medium to the discharge opening A. The period of time required for separating the delivery chamber 4 from the region of increase in volume V until the delivery chamber 4 is completely closed depends on the closing angle α _s and the rotational speed n given in FIG. 4 and is calculated as follows: $${\mathrm{Closing\; time\; t}}_{\mathrm{s}}={\mathrm{Closing\; angle\; \alpha }}_{\mathrm{s}}/6*\mathrm{Speed\; n}$$

Finally, in "Phase IV", the delivery medium contained in the delivery chamber 4 is discharged to the discharge port A on the delivery side. The phase IV is initiated in that the inflow-side end section 14 'of the tooth 14 passes over the line of the pressure-side ridge angle f _D , so that the considered delivery chamber 4 is connected to the pressure side and the discharge opening A. A state of the rotary pistons during phase IV is shown schematically in FIG. In this case, the delivery chamber 4 is connected to the discharge opening A and the medium is continuously ejected by the progressive rotation of the rotors 10, 20. At the same time, of course, analogous processes to the above explanations take place in the other delivery chambers.

• 0,25 < t_s/t_L < 1,75;
• bevorzugt 0, 50 < t_s/t_L < 1,5
• besonders bevorzugt 0, 75< t_s/t_L < 1,25

The geometry and the operating parameters of the rotary compressor 1 according to the invention are now designed such that the gas-dynamic shock described above is effectively generated and then utilized to increase the degree of filling of the respective delivery chamber. For this purpose, the rapid separation of the considered delivery chamber 4 takes place within a separation time t _T , which is less than 2.0 times the transit time t _L and, for example, is 1.50 times the transit time t _L. In addition, the separation time t _T and the transit time t _{L are} matched to one another such that they lie in the following preferred ranges:

• 0.25 <t _s / t _L <1.75;
• preferably 0, 50 <t _s / t _L <1.5
• more preferably 0.75 <t _s / t _L <1.25

• Länge der jeweiligen Förderkammer (4) in Förderkammerlängsrichtung,
• Ausbildung und/oder Anordnung der Zuströmöffnung in die jeweilige Förderkammer (4),
• Verwindungswinkel (β) der Rotoren (10, 20),
• Anzahl (n) der Flügel bzw. Zähne (12, 14, 16, 22, 24, 26) pro Rotor.

As can be seen from the above explanations, the geometric influencing variables which influence the operating characteristics of the rotary compressor according to the invention comprise the following variables:

• Length of the respective delivery chamber (4) in delivery chamber longitudinal direction,
• Training and / or arrangement of the inflow opening in the respective delivery chamber (4),
• Twist angle (β) of the rotors (10, 20),
• Number (s) of blades or teeth (12, 14, 16, 22, 24, 26) per rotor.

A modified embodiment of the rotary compressor 1 is shown in Fig. 7 in a schematic sectional view, in a Fig. 4 corresponding operating phase. The embodiment shown in Fig. 7 differs from the previous embodiment in that the control edge 32 has a contour whose shape approximates that of a wing portion, which in the operation of the Rotary compressor, the control edge 32 passes in advance. With this configuration, the inflow of medium into the respective delivery chamber 4 can be effectively controlled by flowing large amounts of medium into the delivery chamber 4 until the end of the closing time t _s , while the delivery chamber 4 is disconnected as quickly as possible when the closing time t _s expires, in order to prevent in this way a "fuming" of the gas-dynamic shock generated in the delivery chamber 4 particularly effective and to achieve the best possible filling of the delivery chamber 4. The control edge 32 may also assume a somewhat flattened shape than shown in FIG. 7 and, in a preferred embodiment, may also be adjustable as a function of the operating parameters of the rotary compressor 1, for example as a function of the operating speed, etc.

Claims (12)

Method for operating a rotary compressor (1) with twisted rotors (10, 20) for compressing gaseous media, in which
in each of an inflow side (4 ') to an outlet side (4'') in the delivery chamber longitudinal flow direction through the delivery chamber (4) by rapidly separating from a region of the increase in volume (V) a gas-dynamic shock is generated, and
a closing time (t _S ) from the separation of the relevant, in Förderkammerlängsrichtung flowed through the conveying chamber (4) from the region of the increase in volume (V) to close the relevant delivery chamber (4) on the inflow side (4 ') is dimensioned such that the filling of the delivery chamber (4) is increased by shock charging. A method according to claim 1, characterized in that the operation of the rotary compressor (1) by changing geometrical parameters and / or the rotational speed of the rotary compressor (1) is controlled taking into account the temperature and the type of gaseous medium. A method according to claim 1 or 2, characterized in that the rapid separation takes place within a separation time (t _T ) in which the rotors (10, 20) in each case a rotation angle of the amount of twisting angle (β), and which is less than that the transit time (t _L) 2.0 times of the gas-dynamic surge for passing through the respective feed chamber (4) in the conveying chamber the longitudinal direction. Method according to one of claims 1 to 3, characterized in that the closing time (t _S ) is less than 1.75 times the running time (t _L ). Rotary piston compressor (1) for compressing gaseous media, with
two twisted rotors (10, 20) enclosed by a housing (2) and each having at least three vanes or teeth (12, 14, 16, 22, 24, 26) for forming a number of delivery chambers (4) between the vanes or vanes Teeth and the inner wall (2 ') of the housing (2), and
at least part-axial, one-sided inflow of the gaseous medium into a relevant delivery chamber (4) through which flow in the delivery chamber longitudinal direction and an area of an increase in volume (V) formed by delivery chambers,
wherein the geometric parameters and the rotational speed of the rotary compressor (1) are coordinated and dimensioned taking into account the temperature and the nature of the gaseous medium such that a rapid separation of the respective delivery chamber (4) from the area of increase in volume (V) to produce a gas-dynamic Pushes done, and
a closing time (t _S ) from the separation of the relevant delivery chamber (4) from the area of the increase in volume (8) until the closing of the respective delivery chamber (4) on the inflow side (4 ') is set such that the filling of the relevant delivery chamber (4) is increased by shock charging. Rotary piston compressor according to claim 5, characterized in that the geometric parameters and the speed of the compressor (1) below Considering the temperature of the gaseous medium so matched and dimensioned that
the closing time (t _S ) is less than 1.75 times a running time (t _L ) of the gas-dynamic impact for passing through the relevant delivery chamber (4) in the delivery chamber longitudinal direction, and
a separation time (t _T ), in which the rotors (10, 20) each pass through a rotation angle of the amount of the twisting angle (β) is less than 2.0 times the running time (t _L ). Rotary piston compressor according to claim 5 or 6, characterized in that an inflow opening (30) is provided, which at least at least partially permits phased and an inflow chamber in the conveying direction longitudinal to the respective feed chamber (4). Rotary piston compressor according to claim 7, characterized in that the inflow opening (30) is limited at least in sections by a control edge (32) whose shape preferably approximates that of a vane or tooth section, which during operation of the rotary compressor (1) the control edge (32 ) happened in advance. Rotary piston compressor according to claim 7 or 8, characterized in that the inflow opening (30) has an adjustable geometry, and in particular the control edge (32) is adjustable. Rotary piston compressor according to claim 5 to 9 or method according to one of claims 1 to 4, characterized in that the separation time (t _T ) is less than 1.75 times, preferably 1.5 times, particularly preferably 1.0 -fold, further particularly preferred 0.75 times, most preferably 0.5 times the transit time (t _L ). Rotary piston compressor according to one of claims 5 to 10 or method according to one of claims 1 to 4, characterized in that the ratio between the closing time (t _S ) and the transit time (t _L ) is in the following ranges: - 0.25 <t _S / t _L <1.75; preferably 0.50 <t _S / t _L <1.50; more preferably 0.75 <t _S / t _L <1.25. Rotary piston compressor according to one of claims 5 to 11 or method according to one of claims 2 to 4, characterized in that the geometric influencing variables comprise at least one or more of the following variables: Length of the respective delivery chamber (4) in delivery chamber longitudinal direction, - Training and / or arrangement of the inflow opening in the respective delivery chamber (4), Torsion angle (β) of the rotors (10, 20), - Number (n) of the wings or teeth (12, 14, 16, 22, 24, 26) per rotor.

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