Element, device and method for compressing a gas

Abstract

Element, device and method for compressing a gas. The element has a housing (2) in which a first and a second rotor (3, 4) with a respective axis of rotation are mounted, the housing (2) being provided with an axial outlet opening (8) formed in particular by: - a tongue-shaped protrusion (14) between a first and a second proximal edge (9b), wherein the edges of the tongue-shaped protrusion (14) are formed by at least a first and a second tongue edge (13a, 13b), wherein the first or second tongue edge (13a, 13b) is further from the axis of rotation of the first or second rotor (3, 4) than the second or first tongue edge (13a, 13b); characterized in that the first tongue edge (13a) has a first tongue edge radius with respect to the first axis of rotation that is smaller than the parallel radius of the first geometric path with respect to the first axis of rotation, said path being traced by the most distant contact points from the first axis of rotation between the end surfaces of the first and second blades (5a, 5b).

Description

TECHNICAL FIELD

[0001] The present invention relates to elements, devices and methods for compressing a gas. BACKGROUND

[0002] Several types of elements for compressing a gas are known from the prior art.

[0003] In a rotary displacement element, the element comprises a housing having an inner space in which one or more rotors having parallel axes of rotation are rotatably mounted and adjacent or almost adjacent to the wall of the inner space, for example two screw rotors which can rotate in opposite directions of rotation in unison and in contact or almost in contact with their blades.

[0004] The housing is provided with an inlet for sucking in the gas to be compressed into the inner space and an outlet for discharging the compressed gas from the inner space.

[0005] The gas sucked in through the inlet is compressed by the screw rotors through compression cavities between the blades of the rotors, which become smaller and smaller as the rotors turn or rotate.

[0006] This rotation also moves the compression cavities from the inlet to the outlet.

[0007] The outlet comprises, consists of or is defined by an outlet opening in the housing.

[0008] The outlet opening can be positioned as a so-called axial outlet opening in an end face of the inner space corresponding to an end surface of the screw rotors and / or designed as a radial port extending from the end face of the rotor surrounding inner space.

[0009] This axial outlet opening has a specific shape, viewed in the direction parallel to the axes of rotation, based on the shape of the compression cavities and the screw rotors have in the end surface of the screw rotors.

[0010] More specifically, this shape is generally determined by a so-called sealing line which is a geometric line corresponding to the trajectory of the contact points between the end surfaces of the rotors during their rotation in contact or almost in contact with each other. The sealing line thus separates a compression cavity at high pressure, i.e. in the last phase of its compression cycle, from another compression cavity at low pressure and thus separates the high pressure gas from the low pressure gas in the inner space.

[0011] The term "contact point" here does not necessarily refer to a direct contact point, but to a point on the outer surface of a rotor at which it is in contact or almost in contact with the other rotor during rotation, or in other words at which it is located at a minimum distance from the other rotor which is of the order of less than 1 mm.

[0012] Due to the shape of the sealing line and due to the specific position of the outlet opening in the end face of the inner space, the compression chamber will be connected with the outlet at the right time, so that the compressed gas located in the compression chamber can leave the housing through the outlet opening at the desired pressure, usually slightly above the outlet pressure, and without too much loss.

[0013] In addition, the outlet opening is located at a position where the blades of the two rotors rotate into contact or almost into contact with each other on the outlet side of the screw compressor element, i.e. at a position where the compression chamber is located on the outlet side.

[0014] The shape of the outlet opening is determined by its edges, which comprise two so-called proximal edges and two so-called distal edges.

[0015] Each proximal edge generally follows the base of the blade of one of the rotors. Or, in other words, the proximal edge corresponds to a geometric path which corresponds to a part of the trajectory which the base of the blade describes during the rotation of the rotor in question.

[0016] The base of the blade is the part of the rotor which has the smallest limiting radius.

[0017] Each distal edge generally follows a part of the trajectory of the end of the end surface of the blade of one of the rotors when this end surface is rotated towards the other rotor but has not yet come into contact or almost into contact with the other rotor.

[0018] Between the two proximal edges a tongue-shaped protrusion or so-called tongue is formed, the shape of which is determined by the sealing line.

[0019] The term "tongue-shaped" is used here to mean that the protrusion, viewed in a direction parallel to the axis of rotation, has an elongated shape formed by two axial lateral tongue flanks which start from a bottom or base and finally converge into a possibly truncated end, or in other words, generally similar to the shape of a cross-section of the complete free end of a human tongue.

[0020] More specifically, viewed in a direction parallel to the axis of rotation, the end of the tongue-shaped protrusion is formed by the contact points at which the end surfaces of the blades of the rotors first come into contact or almost into contact with each other, and each of the two tongue flanks of the tongue-shaped protrusion extending from the end is formed by a part of the trajectory of one of the two different contact points between the end surfaces of the blades. Thereby, the tongue-shaped protrusion extends in a direction opposite to the direction in which the rotors rotate between their axes of rotation.

[0021] The tongue is a limiting part of the outlet opening, said part being located at a position where the end surfaces of the blades of the two rotors rotate in contact with or almost in contact with each other and preventing the backflow of the compressed gas through the outlet opening to the inlet side of the inner space, which would otherwise occur between the two different contact points.

[0022] However, the known shape of the outlet opening has a number of drawbacks.

[0023] One drawback is that during the last phase of the fluidic contact of the compression chamber with the outlet opening, the gas in the compression chamber is subject to so-called dynamic over-compression. This is because the area of the compression chamber which at this time is in fluidic contact with the outlet opening is insufficient to obtain a proper and smooth evacuation of the compressed gas from the compression chamber to the outlet.

[0024] This is combined with a locally very high pressure in the compression chamber for which the element is not designed and which can lead to damage of the element.

[0025] Another drawback is that there is always a part of the compressed gas in the compression chamber which cannot exit the inner space through the outlet opening. This is because, by further rotation of the rotors, each of the contact points, seen in a direction parallel to the axis of rotation, advances from the end of the tongue over the edge of the tongue to the bottom of the tongue; and after the contact points have reached the bottom of the tongue, the compression chamber is no longer in fluidic connection with the outlet opening.

[0026] The above-mentioned part of the compressed gas will leak towards the inlet side of the inner cavity when the rotors are further rotated and thus cause an efficiency loss. SUMMARY

[0027] It is an object of the present invention to provide a solution to at least one of the previously mentioned and / or other drawbacks.

[0028] Subject of the present invention is an element for compressing a gas, wherein said element comprises a housing enclosing an inner space, a helical first rotor and a helical second rotor rotatably mounted in said inner space and adjacent or almost adjacent to a wall of said inner space,

[0029] so that during a rotation period of said first rotor and said second rotor in opposite rotation directions, a first blade of said first rotor and a second blade of said second rotor rotate in contact with or almost in contact with each other at a position between said first rotor and said second rotor,

[0030] wherein said housing is provided with an inlet for guiding a gas to be compressed towards and into said inner space and an outlet for guiding a compressed gas away from and out of said inner space,

[0031] wherein said outlet comprises an axial outlet opening abutting said inner space,

[0032] wherein, seen in a direction parallel to a first rotation axis of the first rotor and a second rotation axis of the second rotor, the outlet opening is formed by:

[0033] - a first distal edge which is located entirely within a first rotation angle around the first rotation axis in which the end surface of the first vane facing the outlet opening rotates during the rotation period towards or within a maximum rotation circle of the end surface of the second vane facing the outlet opening;

[0034] - a second distal edge which is located entirely within a second rotation angle around the second rotation axis in which the end surface of the second vane rotates during the rotation period towards or within a maximum rotation circle of the end surface of the first vane facing the outlet opening;

[0035] - a first proximal edge which is located entirely within the first rotation angle at a smaller distance from the first rotation axis than the first distal edge;

[0036] - a second proximal edge which is located entirely within the second rotation angle at a smaller distance from the second rotation axis than the second distal edge;

[0037] - a tongue-shaped protrusion between the first proximal edge and the second proximal edge,

[0038] the protrusion being first positioned within a third rotation angle around the first rotation axis in which the end surface of the first vane and the end surface of the second vane rotate in contact with or nearly in contact with each other during the rotation period and secondly positioned within a fourth rotation angle around the second rotation axis in which the end surface of the first vane and the end surface of the second vane rotate in contact with or nearly in contact with each other during the rotation period,

[0039] wherein the tongue-shaped protrusion is fastened to a base sheet of the housing and extends from the base sheet in a direction opposite to the direction in which the first rotor and the second rotor rotate between the first rotation axis and the second rotation axis during the rotation period, and

[0040] wherein an edge of the tongue-shaped protrusion is formed by at least a first tongue rim and a second tongue rim extending from the base sheet, wherein the first tongue rim is further away from the rotation axis of the first rotor than the second tongue rim and the second tongue rim is further away from the rotation axis of the second rotor than the first tongue rim;

[0041] characterized in that, over the entire length of said first tongue, said first tongue radius of the first tongue relative to said first rotation axis is smaller than a first geometric path parallel to said first tongue radius relative to said first rotation axis, said first geometric path being described during said rotation period by the contact point furthest from said first rotation axis between said end surface of said first blade and said end surface of said second blade.

[0042] The "edge" of the tongue-shaped protrusion refers to the part of the circumference of the tongue-shaped protrusion that partly forms the outlet opening.

[0043] In this context, the "tongue radius" refers to the straight-line distance between a point of the tongue and the rotation axis, which can vary over the length of the tongue.

[0044] Preferably, the first tongue radius is at least 2.5% smaller than said radius of the first geometric path over the entire length of the first tongue.

[0045] By making the first tongue radius of the first tongue smaller than the radius of the first geometric path, the outlet opening will effectively become larger than the outlet opening in the known element where the first tongue coincides with the first geometric path when observed in a direction parallel to the first and second rotation axes.

[0046] It is important to note that this change in the shape of the outlet opening at the first tongue position is counterintuitive, as it results in the outlet opening being fluidly connected to the low-pressure zone of the inlet side of the internal space at certain times during the rotation of the screw rotor, which is known to cause leakage of compressed gas to the inlet side.

[0047] This change in the shape of the outlet opening will intentionally create these leaks in order to expel a desired portion of the compressed gas to reduce the over-compression in the compression chamber.

[0048] An advantage is therefore that this shape of the outlet opening will greatly reduce the aforementioned over-compression.

[0049] It is noted that both the over-compression of the gas in the compression chamber and the leakage of compressed gas to the inlet side occur at the first tongue, and thus close to each other, when observed in a direction parallel to the first and second rotation axes.

[0050] In addition, the shape of the outlet opening will also allow more compressed gas in the compression chamber to exit the internal space through the outlet opening and ultimately leave the element compared to the known element.

[0051] This results in a relative specific energy consumption (SER), or a reduction in the power demand per unit of compressed gas produced, in the element.

[0052] Thus, the element has a higher efficiency than known elements.

[0053] In a preferred embodiment of the element according to the invention, over the entire length of the second tongue edge, the second tongue edge radius of the second tongue edge relative to the second axis of rotation is smaller than the radius of a second geometrical path parallel to the second tongue edge radius relative to the second axis of rotation, the second geometrical path being traced during the rotation period by the contact point between the end surface of the first blade and the end surface of the second blade that is farthest from the second axis of rotation.

[0054] Preferably, the second tongue edge radius is at least 2.5% smaller than the radius of the second geometrical path over the entire length of the second tongue edge.

[0055] Also by making the second tongue edge radius smaller than the radius of the second geometrical path, the outlet opening will effectively become larger than in known elements in which the second tongue edge coincides with the second geometrical path when viewed in a direction parallel to the first and second axes of rotation.

[0056] The advantages thereof are obviously similar to the above-mentioned advantages obtained by making the first tongue edge radius smaller than in known elements.

[0057] In another preferred embodiment of the element according to the invention, the first rotor is a male threaded rotor and the second rotor is a female threaded rotor.

[0058] In practice, in the case where the male threaded rotor and the female threaded rotor are mounted in the internal space of the element, the last stage of compression in which the compression chamber is in fluid contact with the outlet opening and the gas in the compression chamber is over-compressed touches the base of the female threaded rotor.

[0059] Thus, the percentage reduction in the tongue edge radius of the tongue edge closest to the female threaded rotor will have a relatively large advantage over the same percentage reduction in the tongue edge radius of the tongue edge closest to the male rotor.

[0060] For example, in the case where only the first tongue edge radius is smaller than the radius of the first geometrical path and the second tongue edge radius is not smaller than the radius of the second geometrical path, the result is that the case where the first rotor is a male rotor and the second rotor is a female rotor is more advantageous than the case where the first rotor is a female rotor and the second rotor is a male rotor.

[0061] In another preferred embodiment of the element according to the invention, the outlet opening is also formed by a connecting edge of the tongue-shaped protrusion, the connecting edge connecting the first tongue edge and the second tongue edge, such that the tongue-shaped protrusion has a truncated shape at the connecting edge, when viewed in a direction parallel to the first and second axes of rotation.

[0062] Due to the connecting edge between the first and second tongue rim and the associated truncated shape of the tongue protrusion, the area of the outlet opening will increase.

[0063] This will have the effect of further reducing over-compression in the compression chamber and further reducing the relative power consumption.

[0064] In another preferred embodiment of the element according to the application, the element is a screw compressor element, preferably an oil-free screw compressor element.

[0065] However, the scope of the application does not exclude that the screw compressor element is a fluid-injected screw compressor element, an oil-free screw vacuum pump element, a fluid-injected screw vacuum pump element, an oil-free screw blower element or a fluid-injected screw blower element.

[0066] In another preferred embodiment of the element according to the application, as seen in a direction parallel to the first and second rotational axis, the distance from at least a portion of the first distal edge to the first rotational axis is smaller than the radius of the maximum rotation circle of the end surface of the first blade.

[0067] In another preferred embodiment of the element according to the application, as seen in a direction parallel to the first and second rotational axis, the distance from at least a portion of the second distal edge to the second rotational axis is smaller than the radius of the maximum rotation circle of the end surface of the second blade.

[0068] By making the distance between, on the one hand, the first and / or second distal edge and, on the other hand, the first or second rotational axis, respectively, smaller than the radius of the maximum rotation circle of the end surface of the first or second blade, the area of the compression chamber in fluid contact with the outlet opening during the rotation period can be reduced as desired at positions where the end surface of the first blade and the end surface of the second blade have not yet come into contact with each other or close to coming into contact with each other and where there is also no over-compression in the compression chamber during the rotation period.

[0069] In this way, the pressure ratio, i.e. the ratio of the outlet pressure to the inlet pressure, across the element is increased.

[0070] In another preferred embodiment of the element according to the application, as seen in a direction parallel to the first and second rotational axis, in the third rotational angle, the radius of the first proximal edge relative to the first rotational axis is equal to or smaller than the radius of the base of the first blade relative to the first rotational axis.

[0071] In another preferred embodiment of the element according to the invention, the radius of the second proximal edge relative to the second rotation axis is equal to or smaller than the radius of the base of the second vane relative to the second rotation axis, as seen in a direction parallel to the first rotation axis and the second rotation axis, in the fourth rotation angle.

[0072] By taking the radius of the first proximal edge and / or the second proximal edge equal to or smaller than the radius of the base of the first vane or the second vane, respectively, in the third rotation angle or the fourth rotation angle, respectively, the area of the compression chamber in fluid contact with the outlet opening within this third rotation angle or fourth rotation angle, respectively, will be kept as large as possible.

[0073] The problem of over-compression in the compression chamber exactly within this third rotation angle and fourth rotation angle is significant in known elements for compressing a gas.

[0074] Keeping the area of the compression chamber in fluid contact with the outlet opening within this third rotation angle or fourth rotation angle, respectively, as large as possible will minimize this problem of over-compression in the compression chamber.

[0075] In another preferred embodiment of the element according to the invention, the distance from at least a part of the first proximal edge to the first rotation axis is larger than the radius of the base of the first vane, as seen in a direction parallel to the first rotation axis and the second rotation axis, outside the third rotation angle.

[0076] In another preferred embodiment of the element according to the invention, the distance from at least a part of the second proximal edge to the second rotation axis is larger than the radius of the base of the second vane, as seen in a direction parallel to the first rotation axis and the second rotation axis, outside the fourth rotation angle.

[0077] By taking the distance between the first proximal edge and / or the second proximal edge, on the one hand, and the first rotation axis or the second rotation axis, on the other hand, respectively, larger than the radius of the base of the first rotor or the second rotor, respectively, outside the third rotation angle or the fourth rotation angle, respectively, the area of the compression chamber in fluid contact with the outlet opening during the rotation period can be reduced as desired at positions where the first vane and the second vane have not yet come into contact with each other or into close contact with each other and there is no over-compression yet in the compression chamber.

[0078] In this way, the pressure ratio, i.e. the ratio of the outlet pressure to the inlet pressure, across the element is increased.

[0079] The invention also relates to a device for compressing a gas, the device comprising an element according to the invention.

[0080] Needless to say, the advantages associated with such a device are the same as those of the element in question.

[0081] The present invention also relates to a method for discharging compressed gas from an element for compressing gas according to the present invention, wherein said method comprises the step of discharging said compressed gas from said interior space through said outlet opening, characterized in that, seen in a direction parallel to said first and second rotational axis, at no time during said rotational period, a contact point between said end surface of said first vane and said end surface of said second vane overlaps said tongue-shaped protrusion.

[0082] At and between the first and second contact points of the first and second rotors, leakage of compressed gas to the inlet side of the interior space can occur, which has the advantages as mentioned above. BRIEF DESCRIPTION OF DRAWINGS

[0083] For a better understanding of the features of the present invention, some preferred embodiments of an element for compressing gas according to the present invention, a device equipped with said element and a method for compressing gas according to the present invention will be described below by way of example, without any limiting features, with reference to the accompanying drawings, in which:

[0084] Figure 1 An element for compressing gas according to the present invention is schematically shown;

[0085] Figure 2 A cross-section along the center line II-II is shown, wherein the axial outlet opening of the element is visible; Figure 1 Figure 1

[0086] Figure 3 The same view as in Fig. 1 is shown, but it is a known element with a known axial outlet opening; Figure 2

[0087] The axial outlet opening of the element of Fig. 1 is shown superimposed and horizontally mirrored on the known axial outlet opening of the element of Fig. 2. Figure 4 DETAILED DESCRIPTION Figure 2 Figure 3

[0088] Figure 1 An element for compressing gas according to the present invention, in this case a screw compressor element 1, is schematically shown.

[0089] It comprises a housing 2 enclosing an interior space, two helical rotors 3, 4 with vanes 5 rotatably mounted in said interior space and adjacent or almost adjacent to the walls of the interior space, i.e. a male first rotor 3 and a female second rotor 4 which can be rotationally fitted into each other.

[0090] ​​​​​In this case, but not essential for the present application, the screw compressor element 1 is an oil-free screw compressor element 1, which means that no oil is injected into the housing 2 to lubricate, cool and / or seal the rotors 3, 4.

[0091] Alternatively, the screw compressor element 1 can also be an oil-injected screw compressor element, a water-injected screw compressor element, an oil-free screw vacuum pump element, an oil-injected screw vacuum pump element, a water-injected screw vacuum pump element, an oil-free screw blower element, an oil-injected screw blower element or a water-injected screw blower element.

[0092] The housing 2 is provided with an inlet 6 for guiding the gas to be compressed towards and into the interior space and an outlet 7 for guiding the compressed gas away from and out of the interior space. The outlet 7 comprises an axial outlet opening 8 adjoining the interior space in the housing 2, i.e. a physical opening in the housing 2.

[0093] The scope of the present application does not exclude that the outlet also comprises radial ports extending from an end face of the interior space containing the outlet opening 8 around the rotors.

[0094] Figure 2 and Figure 3 are schematically shown, respectively, the outlet opening 8 according to the present application and the outlet opening 8 of a known element, respectively, as seen in a direction parallel to the rotational axis of the first rotor 3 and the second rotational axis of the second rotor 4, wherein the housing 2 is not shown for the sake of clarity.

[0095] The outlet opening 8 comprises a plurality of edges 9a, 9b, 10a, 10b, 13a, 13b.

[0096] First, the outlet opening comprises two proximal edges 9a, 9b. In the outlet opening 8 of the known element as shown in Figure 3 as seen in a direction parallel to the first rotational axis and the second rotational axis, the first proximal edge 9a coincides completely with a part of the trajectory traced by the base 11a of the blades 5 of the first rotor 3. As seen in a direction parallel to the first rotational axis and the second rotational axis, Figure 3 the second proximal edge 9b in the known element coincides completely with a part of the trajectory traced by the base 11b of the blades 5 of the second rotor 4.

[0097] In the outlet opening 8 according to the present application as shown in Figure 2In the outlet opening 8 of the element according to the application as shown, the radius of the first proximal edge 9a with respect to the first rotation axis or the radius of the second proximal edge 9b with respect to the second rotation axis, respectively, can be as large as the radius of the geometric path of the base 11a of the first rotor 3 or of the base 11b of the second rotor 4, respectively, as seen in the direction parallel to the first rotation axis and to the second rotation axis. However, the present application does not exclude that the radius of the first proximal edge 9a is larger than the radius of the geometric path of the base 11a outside a third rotation angle around the first rotation axis at which the first blade 5a of the first rotor 3 and the second blade 5b of the second rotor 4 rotate in contact with or almost in contact with each other, as seen in the direction parallel to the first rotation axis and to the second rotation axis. The present application does not exclude either that the radius of the second proximal edge 9b is larger than the radius of the geometric path of the base 11b outside a fourth rotation angle around the second rotation axis at which the first blade 5a of the first rotor 3 and the second blade 5b of the second rotor 4 rotate in contact with or almost in contact with each other, as seen in the direction parallel to the first rotation axis and to the second rotation axis.

[0098] Furthermore, the outlet opening 8 comprises two distal edges 10a, 10b.

[0099] For the outlet opening 8 of the known element as shown in Figure 3 The distal edges 10a, 10b are those edges of the outlet opening 8 which, as seen in the direction parallel to the first rotation axis and to the second rotation axis, coincide completely with a part of the trajectory of the tip 12 of the blade 5 of the rotor 3, 4.

[0100] With regard to the outlet opening 8 known in Figure 3 The first distal edge 10a coincides completely with a part of the trajectory of the tip 12 of the blade 5 of the first rotor 3 within a first rotation angle around the first rotation axis, wherein, as seen in the direction parallel to the first rotation axis and to the second rotation axis, the tip 12 of the blade 5 of the first rotor 3 rotates during the rotation period towards or just within the maximum rotation circle of the blade 5 of the second rotor 4. The second distal edge 10b coincides completely with a part of the trajectory of the tip 12 of the blade 5 of the second rotor 4 within a second rotation angle around the second rotation axis, wherein, as seen in the direction parallel to the first rotation axis and to the second rotation axis, the tip 12 of the blade 5 of the second rotor 4 rotates during the rotation period towards or just within the maximum rotation circle of the blade 5 of the first rotor 3.

[0101] In the outlet opening 8 of the known element as shown in Figure 2In the outlet opening 8 of the element according to the application shown, the radius of the first distal edge 10a with respect to the first rotation axis or the radius of the second distal edge 10b with respect to the second rotation axis, respectively, can be as large as the radius of the geometric path of the tip 12 of the blade 5 of the first rotor 3 or of the second rotor 4, respectively, as observed in a direction parallel to the first rotation axis and to the second rotation axis. However, the present application does not exclude that the radius of the first distal edge 10a and / or of the second distal edge 10b, respectively, is smaller than the radius of the geometric path of the tip 12 of the blade 5 of the first rotor 3 or of the second rotor 4, respectively, as observed in a direction parallel to the first rotation axis and to the second rotation axis.

[0102] The piece of casing 2 between the two proximal edges 9a, 9b within the third and fourth rotation angles is a limiting portion, called tongue-shaped protrusion 14 or tongue.

[0103] The shape of this tongue-shaped protrusion 14 is such that Figure 3 In the known outlet opening 8 in More specifically, as observed in a direction parallel to the first rotation axis and to the second rotation axis, both the two tongue flanges 13a, 13b of the tongue-shaped protrusion 14 follow, during the rotation period, the geometric path of different points of contact between the end surfaces of the blades 5 of the first rotor 3 and of the second rotor 4, said end surfaces facing the outlet opening 8.

[0104] The tongue-shaped protrusion 14 is fastened to the base sheet of the casing 2 as a portion of the casing 2 and extends from this base sheet in a direction opposite to the direction in which the first rotor 3 and the second rotor 4 rotate between the first rotation axis and the second rotation axis during the rotation period.

[0105] The first tongue flange 13a is farther from the rotation axis of the first rotor 3 than the second tongue flange 13b, and the second tongue flange 13b is farther from the rotation axis of the second rotor 4 than the first tongue flange 13a.

[0106] According to the embodiment of the application as shown in Figure 2 As observed in a direction parallel to the first rotation axis and to the second rotation axis, over the entire length of the first tongue flange 13a, the first tongue flange radius of the first tongue flange 13a with respect to the first rotation axis is smaller than the radius of a first geometric path parallel to this first tongue flange radius, said first geometric path being described by the contact point between the end surfaces of the blades 5 of the first rotor 3 and of the second rotor 4 that is farthest from the first rotation axis during the rotation period.

[0107] Thus, as observed in a direction parallel to the first rotation axis and to the second rotation axis, the area of the tongue-shaped protrusion 14 in the outlet opening 8 according to the application in Figure 2 is smaller than the area of the tongue-shaped protrusion 14 in the outlet opening 8 in Figure 3the known outlet opening 8 in the known element. It is noted that this adjustment is counterintuitive, as this adjustment implies that gas being compressed is deliberately leaked from the outlet 7 to the inlet side of the element.

[0108] In other words, Figure 2 the outlet opening 8 according to the invention in the element Figure 3 is larger, i.e. has a larger area, than the known outlet opening 8. As already mentioned, it is more specifically the tongue-shaped protrusion 14 that is larger in the outlet opening 8 according to the invention than in the known element. Figure 3 the tongue-shaped protrusion 14 in the element according to the invention is smaller than in the known element.

[0109] Preferably, the first tongue rim radius is at least 2.5% smaller than said radius of the first geometric path over the entire length of the first tongue rim 13a.

[0110] The radius can be more than 2.5% smaller.

[0111] Within the scope of the invention, the first edge of the base sheet of the housing 2 to which the tongue-shaped protrusion 14 is fastened does not exclude that it still at least partly overlaps with the first geometric path, as seen in a direction parallel to the first and second rotational axes.

[0112] In the case of the outlet opening 8 according to the invention in the element Figure 2 as seen in a direction parallel to the first and second rotational axes, the second tongue rim radius of the second tongue rim 13b relative to the second rotational axis is also smaller than the radius of a second geometric path parallel to this second tongue rim radius, said second geometric path being delineated by the contact points between the end surfaces of the blades 5 of the first and second rotors 3 and 4 that are farthest from the second rotational axis during a rotational period, over the entire length of the second tongue rim 13b.

[0113] Within the scope of the invention, the second edge of the base sheet of the housing 2 to which the tongue-shaped protrusion 14 is fastened does not exclude that it still at least partly overlaps with the second geometric path, as seen in a direction parallel to the first and second rotational axes.

[0114] In this case, in order to further reduce the element according to the invention compared to the known element as shown in Figure 3 the tongue-shaped protrusion 14 in the element according to the invention has a truncated shape. Figure 2 the area of the tongue-shaped protrusion 14 in the element according to the invention, Figure 2 the outlet opening 8 in the element according to the invention is additionally formed by a connecting edge 15 of the tongue-shaped protrusion 14, said connecting edge 15 connecting the first tongue rim 13a and the second tongue rim 13b, such that in the element according to the invention Figure 3 the end 16 of the tongue-shaped protrusion 14 is cut off in the known element, such that in the element according to the invention Figure 2 the tongue-shaped protrusion 14 according to the invention has a truncated shape.

[0115] AsFigure 2 In the middle it can be seen that the edge of the outlet opening 8 is rounded. This is to facilitate the manufacture of the housing 2 by casting.

[0116] In Figure 4 In the middle, Figure 2 and Figure 3 The outlet openings 8 of Figures 1 and 2 are shown superimposed on each other and horizontally mirrored, thus visually showing where the outlet openings 8 are manufactured larger.

[0117] In Figure 4 It can be clearly seen in the middle that the tongue-shaped protrusion 14 is smaller in the outlet opening 8 according to the application and that the tip 16 is cut off.

[0118] The operation of the screw compressor element 1 is very simple and as follows.

[0119] During operation, the screw rotors 3, 4, together with their blades 5, rotate in contact with each other or almost in contact with each other.

[0120] The gas to be compressed, for example ambient air, is sucked in through the inlet 6.

[0121] The sucked-in gas to be compressed enters the so-called compression chamber 17 between the blades 5 of the screw rotors 3, 4.

[0122] The rotation of the screw rotors 3, 4 moves the compression chamber 17 towards the outlet 7 and at the same time it becomes smaller, so that the gas is compressed in this chamber.

[0123] When viewed in the direction parallel to the first and second rotation axes, when the outlet side of the inner space of the compression chamber 17 finally overlaps the outlet opening 8, a fluid connection will be formed between the compression chamber 17 and the outlet 7, so that the now compressed gas from the compression chamber 17 will leave the screw compressor element 1.

[0124] Figure 2 and Figure 3 indicates the compression chamber 17.

[0125] The shape of the outlet opening 8 is determined by the aforementioned sealing line and is chosen so that the moment of fluid connection between the compression chamber 17 and the outlet 7 occurs in the last phase of compression and also ensures that the fluid connection is broken at the moment when the compression chamber 17 in question re-connects fluidically with the inlet 6. Thus, the sealing line forms a separation between the high-pressure gas on the one hand and the low-pressure gas on the other hand in the inner space.

[0126] Figure 2 and Figure 3 It is clearly shown in the comparison that Figure 2 the time of fluid connection of the compression chamber 17 with the outlet opening 8 in Figure 3the compression chamber 17 is longer. There will also be an intentional leakage from the outlet 7 to the inlet side of the inner space compared to known screw compressor elements.

[0127] Thus, substantially all of the compressed gas has the opportunity to escape from the compression chamber 17. Compared to the case where Figure 2 the compression chamber 17 is longer, there will also be an intentional leakage from the outlet 7 to the inlet side of the inner space compared to known screw compressor elements. Figure 3 In the case where Figure 2 the compression chamber 17 is longer, the amount of compressed gas that can leak directly from the compression chamber 17 to the inlet side of the inner space will be less.

[0128] There will also be less over-compression in the compression chamber 17, i.e. immediately after the compression chamber 17 has closed from the outlet opening 8 Figure 2 the maximum pressure in the compression chamber 17 will be lower than in the case where Figure 3 the compression chamber 17 is longer.

[0129] As already mentioned, this has the effect of increasing the efficiency of the screw compressor element 1, since the relative power consumption (specific energy requirement, SER) is reduced, or the power produced per unit of compressed gas volume.

[0130] The magnitude of the percentage reduction in the relative power consumption depends on the speed of the compressor element and is generally lower at high speeds of the screw compressor element and higher at the lowest speeds.

[0131] The present invention is in no way limited to the embodiments described by way of example and shown in the drawings, but the element for compressing a gas according to the present invention, the device equipped with said element and the method for compressing a gas according to the present invention can be realized in various shapes and dimensions without departing from the scope of the present invention as defined in the claims.

Claims

1. A component for compressing gas, The component includes a housing (2) that encloses the internal space, a helical first rotor (3) and a helical second rotor (4) rotatably mounted within the housing and adjacent to the wall of the internal space. During the rotational cycle of the first rotor (3) and the second rotor (4) in opposite rotational directions, the first blade (5a) of the first rotor (3) and the second blade (5b) of the second rotor (4) rotate in contact with or nearly in contact with each other at a position between the first rotor (3) and the second rotor (4). The outer casing (2) is provided with an inlet (6) for guiding the gas to be compressed toward and into the internal space and an outlet (7) for guiding the compressed gas away from and away from the internal space. The outlet (7) therein includes an axial outlet opening (8) adjacent to the interior space. in, Viewed in a direction parallel to the first rotation axis of the first rotor (3) and the second rotation axis of the second rotor (4), the axial outlet opening (8) is formed by the following: - A first distal edge (10a) is located entirely within a first rotation angle about the first rotation axis, in which the end surface of the first blade (5a) facing the axial outlet opening (8) rotates toward the maximum rotation circle of the end surface of the second blade (5b) facing the axial outlet opening (8) or within the maximum rotation circle of the end surface of the second blade (5b) facing the axial outlet opening (8) during the rotation cycle; - The second distal edge (10b) lies entirely within a second rotation angle about the second rotation axis, in which the end surface of the second blade (5b) rotates toward or within the maximum rotation circle of the end surface of the first blade (5a) during the rotation cycle. - The first proximal edge (9a) is completely within the first rotation angle and is located at a distance from the first rotation axis that is smaller than the distance from the first distal edge (10a) to the first rotation axis. - The second proximal edge (9b) is completely within the second rotation angle and is at a smaller distance from the second rotation axis than the second distal edge (10b) is at a smaller distance from the second rotation axis; - A tongue-shaped protrusion (14) between the first proximal edge (9a) and the second proximal edge (9b), the tongue-shaped protrusion being first positioned within a third rotation angle about the first rotation axis and secondly positioned within a fourth rotation angle about the second rotation axis, in the third rotation angle, during the rotation cycle, the end surfaces of the first blade (5a) and the second blade (5b) rotating in contact with or nearly in contact with each other, and in the fourth rotation angle, during the rotation cycle, the end surfaces of the first blade (5a) and the second blade (5b) rotating in contact with or nearly in contact with each other. The tongue-shaped protrusion (14) is fastened to the substrate of the housing (2) and extends from the substrate in a direction opposite to the direction in which the first rotor (3) and the second rotor (4) rotate between the first rotation axis and the second rotation axis during the rotation cycle. The edge of the tongue-shaped protrusion (14) is formed by at least a first tongue edge (13a) and a second tongue edge (13b) extending from the substrate, wherein the first tongue edge (13a) is further away from the first axis of rotation of the first rotor (3) than the second tongue edge (13b) and the second tongue edge (13b) is further away from the second axis of rotation of the second rotor (4) than the first tongue edge (13a); Its features Over the entire length of the first tongue edge (13a), the radius of the first tongue edge (13a) relative to the first axis of rotation is smaller than the radius of the first geometric path parallel to the first tongue edge radius relative to the first axis of rotation, the first geometric path being drawn during the rotation cycle by the contact point furthest from the first axis of rotation between the end surfaces of the first blade (5a) and the second blade (5b), and Wherein, over the entire length of the second tongue edge (13b), the second tongue edge radius of the second tongue edge (13b) relative to the second axis of rotation is smaller than the radius of the second geometric path parallel to the second tongue edge radius relative to the second axis of rotation, the second geometric path being drawn during the rotation cycle by the contact point furthest from the second axis of rotation between the end surfaces of the first blade (5a) and the end surfaces of the second blade (5b).

2. The element for compressing gas according to claim 1, characterized in that... Over the entire length of the first tongue edge (13a), the radius of the first tongue edge is at least 2.5% smaller than the radius of the first geometric path.

3. The element for compressing gas according to claim 1 or 2, characterized in that... Over the entire length of the second tongue edge (13b), the radius of the second tongue edge is at least 2.5% smaller than the radius of the second geometric path.

4. The element for compressing gas according to claim 1 or 2, characterized in that... The first rotor (3) is a male thread rotor and the second rotor (4) is a female thread rotor.

5. The element for compressing gas according to claim 1 or 2, characterized in that... Viewed in a direction parallel to the first and second rotation axes, the axial outlet opening (8) is also formed by the connecting edge (15) of the tongue-shaped protrusion (14), which connects the first tongue edge (13a) and the second tongue edge (13b), such that the tongue-shaped protrusion (14) has a truncated shape at the connecting edge (15).

6. The element for compressing gas according to claim 1 or 2, characterized in that... The component is a screw compressor component (1).

7. The element for compressing gas according to claim 6, characterized in that... The component is an oil-free screw compressor component (1).

8. The element for compressing gas according to claim 1 or 2, characterized in that... Viewed in a direction parallel to the first and second rotation axes, the distance from at least a portion of the first distal edge (10a) to the first rotation axis is less than the radius of the maximum rotation circle of the end surface of the first blade (5a).

9. The element for compressing gas according to claim 1 or 2, characterized in that... Viewed in a direction parallel to the first and second rotation axes, the distance from at least a portion of the second distal edge (10b) to the second rotation axis is less than the radius of the maximum rotation circle of the end surface of the second blade (5b).

10. The element for compressing gas according to claim 1 or 2, characterized in that... Viewed in a direction parallel to the first and second rotation axes, in the third rotation angle, the radius of the first proximal edge (9a) relative to the first rotation axis is equal to or less than the radius of the base of the first blade (5a) relative to the first rotation axis.

11. The element for compressing gas according to claim 1 or 2, characterized in that... Viewed in a direction parallel to the first and second rotation axes, in the fourth rotation angle, the radius of the second proximal edge (9b) relative to the second rotation axis is equal to or less than the radius of the base of the second blade (5b) relative to the second rotation axis.

12. The element for compressing gas according to claim 1 or 2, characterized in that... Viewed in a direction parallel to the first and second rotation axes, outside the third rotation angle, the distance from at least a portion of the first proximal edge (9a) to the first rotation axis is greater than the radius of the base of the first blade (5a).

13. The element for compressing gas according to claim 1 or 2, characterized in that... Viewed in a direction parallel to the first and second rotation axes, outside the fourth rotation angle, the distance from at least a portion of the second proximal edge (9b) to the second rotation axis is greater than the radius of the base of the second blade (5b).

14. An apparatus for compressing gas, characterized in that... The apparatus for compressing gas includes an element for compressing gas according to any one of the preceding claims.

15. A method for discharging compressed gas from an element for compressing gas according to any one of claims 1 to 13, wherein the method comprises the step of discharging the compressed gas from the internal space through the axial outlet opening (8), characterized in that... Viewed in a direction parallel to the first and second rotation axes, at any time during the rotation cycle, there is no point of contact between the end surfaces of the first blade (5a) and the end surfaces of the second blade (5b) that overlaps with the tongue-shaped protrusion (14).

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