Abstract
A coupling guard for a rotor, which includes a housing for enclosing the rotor in an inner space of the housing, the housing extending longitudinally along a length of the rotor; a ventilation system for creating a flow of gas in the inner space from a gas inlet to a gas outlet that exhausts outside. The gas inlet includes a pipe extending along a pipe longitudinal axis from outside to inside the housing. The pipe includes a first opening located outside the housing and a second opening located inside the housing in the inner space. The pipe has the second opening close to the rotor when the housing encloses the latter. The second opening has a curved edge wherein a projection of the curved edge onto a plane extending parallel to the longitudinal axis of the pipe and parallel to the axis of longitudinal extension is a segment of curve.
Claims
1. A coupling guard for a rotor, comprising: a housing configured for enclosing the rotor in an inner space of the housing, said housing being configured for extending longitudinally along a length of the rotor around an axis of longitudinal extension of the housing in order to surround at least said length of the rotor; a ventilation system for creating a flow of gas in said inner space from a housing gas inlet to a housing gas outlet from which the gas is exhausted outside of the housing; wherein the gas inlet comprises a pipe extending along a pipe longitudinal axis (L) from outside to inside the housing, said pipe comprising a first opening located outside the housing and a second opening located inside the housing in said inner space, the pipe being configured for having its second opening close to the rotor when the housing encloses the rotor, the second opening comprising at least a curved edge wherein a projection of the curved edge onto a plane extending parallel to the longitudinal axis of the pipe and parallel to the axis of longitudinal extension is a segment of curve, wherein said curved edge is obtained as an intersection of a plane with the pipe, wherein said plane is parallel to a housing axis of longitudinal extension and tilted of an acute angle with respect to the longitudinal axis.
2. The coupling guard of claim 1, wherein said curved edge is concave.
3. The coupling guard of claim 1, wherein the projection of said curve edge is an ellipse or a parabola.
4. The coupling guard of claim 1, wherein said curved edge is symmetric with respect to a plane extending perpendicularly to said housing axis of longitudinal extension and comprising the pipe longitudinal axis.
5. The coupling guard of claim 1, wherein a portion of the second opening delimited by said curved edge is configured for pointing or being directed towards a direction that is the direction of rotation of the rotor.
6. The coupling guard of claim 1, wherein said curved edge is obtained as an intersection of an ellipse with the pipe.
7. The coupling guard of claim 1, wherein the pipe comprises a straight part centered around the longitudinal axis and extending from outside to inside said housing, wherein said straight part directly ends with the second opening.
8. The coupling guard of claim 1, wherein the pipe comprises a straight part centered around the longitudinal axis and extending from outside to inside said housing, wherein said straight part has its end inside the housing coupled to a curved part.
9. The coupling guard according to claim 8, wherein the curved part of the pipe comprises a truncated cone and a curved pipe portion, wherein the second opening is formed by the open base of the truncated cone, wherein an open apex of the truncated cone is coupled to one extremity of said curved portion, the other extremity of said curved portion being coupled to the straight part.
10. The coupling guard according to claim 9, wherein the truncated cone is centered around a cone axis that forms an angle β comprised between 40°-55° with respect to the longitudinal axis.
11. The coupling guard according to claim 1, comprising: two gas inlets, each installed close to one of the longitudinal extremities of the housing, and a gas outlet located substantially at a same distance from each of the two gas inlets and radially at an opposite location.
12. The coupling guard according to claim 1, wherein the gas outlet comprises an exhaust pipe extending perpendicular to the housing axis of longitudinal extension and to the longitudinal axis.
13. A rotating machine, comprising: a first rotating assembly; a second rotating assembly; a rotor coupling the first rotating assembly to the second rotating assembly; and a coupling guard according to claim 1.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] Further description and details of the invention will be described now on the basis of embodiments illustrated by the following figures:
[0014] FIG. 1 Cross sectional front view of a schematic representation of a prior art ventilation system of a coupling guard.
[0015] FIG. 2 Cross sectional side view of the schematic representation of the coupling guard according to FIG. 1 taken along the line A-A.
[0016] FIG. 3 Schematic representation of a coupling guard according to the invention (Front view).
[0017] FIG. 4 Exemplary embodiments of the second opening according to the invention.
[0018] FIG. 5 Schematic illustration of a first preferred embodiment of a pipe according to the invention (Side view).
[0019] FIG. 6 Schematic illustration of a second preferred embodiment of a pipe according to the invention (Side view).
[0020] FIGS. 7A-B Side view of a pipe according to the invention (FIG. 7A) and schematic illustration of streamlines (FIG. 7B) of gas flowing around the pipe according to a top view along the line C-C of FIG. 7A.
[0021] FIG. 8 Schematic illustration of the details of a second opening according to the invention.
DETAILED DESCRIPTION OF INVENTION
[0022] FIGS. 1 and 2 show a prior art coupling guard 1 according to a cross sectional front view (FIG. 1) and side view (FIG. 2). The coupling guard 1 is configured for surrounding and enclosing a rotating coupling member 2 (hereafter simply called rotor) which is typically used for the transmission of rotation power from a first rotating assembly 2A to a second rotating assembly 2B. The coupling guard 1 comprises a ventilation system made of one or several gas (air) inlets 11 and outlets 12, wherein air coming from the outside of the coupling guard 1 enters into the latter through the gas inlet 11, is driven (see the arrows in FIG. 2) into rotation around the rotor 2 by the rotation of the latter around its rotational axis W according to a rotational speed w (due to friction force, the air inside the housing 10 is driven into rotation by the rotating surface of the rotor 2) and then leaves at some time the inner space of the coupling guard 1 through the air outlet 12. In order to improve the air circulation, scoops 13 are used for directing the flows of incoming and leaving air. This circulation of air inside the coupling guard enables to decrease the temperature of the surrounding environment of the rotor 2.
[0023] FIG. 3 shows a schematic front view of a coupling guard 1 according to the invention, wherein the same reference numbers have been taken for features identical or having the same function as those described in FIGS. 1 and 2. The coupling guard 1 comprises a housing 10 configured for surrounding and enclosing the rotor 2 so as to create an enclosed inner space 101 in which a flow of gas circulates from a gas inlet 11 to one or several gas outlets 12 of a ventilation system. The housing is preferably configured for being substantially centered around a rotor 2, and therefore around an axis of longitudinal extension LH that might be identical to the rotational axis w of the rotor 2, so as to surround at least partially a length of the rotor 2. The walls of the housing 10 define the boundaries of said inner space 101 inside which the rotating coupling member is enclosed. The housing 10 is preferentially substantially cylindrical. According to the present invention, the housing 10 comprises preferentially two gas inlets 11, namely a first gas inlet installed close to one of the longitudinal extremities of the housing 10 and a second gas inlet installed close to the other longitudinal extremities of the housing. According to other preferred embodiment, the housing 10 may comprise only one or more than two gas inlets 11 installed along the housing 10. For instance, a single or several gas inlets 11 might be located substantially in the middle of the housing 10 with respect to its length, and one or several gas outlets 12 might be each located at one extremity of the housing 10 with respect to its length, preferentially at least one gas outlet 12 located at each extremity of the housing 10 substantially located radially with respect to the coupling of the rotor 2 with the rotating assemblies 2A or 2B. According to FIG. 3, the two gas inlets 11 are preferentially aligned on a same longitudinal line extending from one of said extremities of the housing to the other one. For instance, the first gas inlet 11 is installed substantially above or close to the coupling of the rotor 2 with the first rotating assembly 2A and the other gas inlet 11 is installed substantially above or close to the coupling of the rotor 2 with the second rotating assembly 2B when the housing surrounds the rotor 2. Preferably, the housing comprises a single gas outlet 12 located at equal distance from each of the gas inlets 11, i.e. substantially in the middle of the housing 10 with respect to its length, and preferentially at a position radially opposite to the position of the gas inlets 11, e.g. typically at the bottom of the housing while the gas inlets are mounted on the top of the housing 10 (i.e. substantially above the rotor 2) when the housing 10 surrounds the rotor 2.
[0024] According to the present invention, the gas inlet 11 comprises a pipe 14, preferentially substantially cylindrical, extending from outside to inside the housing 10 through the housing wall along a longitudinal axis L parallel to at least a part of its axial length. One extremity of the pipe 14 is therefore located on the external side of the housing 10 and another extremity is located within the inner space 101 defined by the housing 10, i.e. on the internal side of the housing 10. The pipe 14 is preferentially a straight pipe. In particular, the longitudinal axis L of the pipe 14 extends towards the rotor 2, e.g. radially towards the rotor 2, preferentially centered one the rotational axis W of the rotor 2 (e.g. an extension of the longitudinal axis L intersecting the rotor 2 or the rotational axis W), or might be off centered with respect to the rotor 2 or its rotational axis W (in this case, the distance between the longitudinal axis or its extension and the rotational axis W being greater than the radius of the rotor so that an extension of the pipe along the longitudinal axis would not enter into contact with the rotor 2). Preferentially, the pipe 14 is installed on the top of the housing 10, i.e. vertically above the rotational axis of the rotor 2 when the housing 10 surrounds the latter. The extremity of the pipe 14 located outside the housing 10 comprises a first opening for letting a gas entering within the inner space 101 of the housing, said gas flowing therefore from outside the housing to inside the housing. Said gas can be air at atmospheric pressure surrounding the coupling guard 1 or gas comprised within a closed chamber outside from the housing and connected to the first opening of said pipe 14.
[0025] The pipe 14 further comprises a second opening 142, which is preferentially close to the rotor 2, e.g. close to a coupling of the rotor 2 with one of said first or second rotating assembly 2A, 2B, and preferably free of contact with the rotor 2. The second opening 142 is located inside the housing 10, within said inner space 101 for ensuring a circulation of the gas which enters by the first opening 141, flows then inside the pipe 14 until reaching the second opening 142, and leaves said pipe 14 through said second opening 142 in order to enter the inner space 101. The gas entering the inner space 101 through said second opening 142 is then driven into rotation by the rotor 2 when the latter rotates around its rotational axis W according to a rotational speed w, and finally, exhausts through the gas outlet 12, enabling therefore to cool down the inner space 101. Indeed, the temperature of the gas entering the inner space 101 is lower than the temperature of the gas exhausted by the gas outlet 12, enabling therefore a cooling of the rotor 2 and its surrounding environment enclosed within the housing 10. According to the present invention, the second opening 142 comprises at least a curved edge C1, i.e. the boundary line of the pipe surface at the location of the second opening comprises at least a curved part.
[0026] The pipe 14 is fixed to the housing 10 so that its second opening 142 is directed in the same direction as the direction of rotation (given by the rotational speed w) of the rotor 2 when the housing 10 encloses the latter (it does not open in a direction opposite to the direction of rotation of the rotor 2). Otherwise said, the pipe 14 comprises a leading edge 14A and a trailing edge 14B (see FIG. 4-7) which includes the curved edge C1, wherein the leading edge 14A faces and contacts first the flow of gas during rotation of the rotor 2, said flow of gas having to flow from the leading edge 14A to the trailing edge 14B when rotating around the rotational axis W of the rotor 2 during the rotation of the latter, the trailing edge 14B being opposite to the leading edge 14A (notably with respect to a cross sectional view passing longitudinally through the middle of the pipe and perpendicularly to the longitudinal axis of the housing 10, i.e. perpendicularly to the rotational axis W of the rotor 2 when the housing encloses the latter). According to the pipe 14 position and shape with respect to the housing 10 and the rotor 2, and as shown in FIGS. 7A and 7B which show a pipe according to the invention respectively from a side view and top view, streamlines 71 of gas flow (the flow direction is schematically represented by the arrow 72) separate in front of the leading edge 14A for joining together after the trailing edge 14B, creating in front of the second opening 142, more precisely in front of the curved edge C1, a negative pressure with respect to the pressure at the first opening 141, this pressure difference between the first opening 141 and the second opening 142 creating a flow of gas from the first opening 141 to the second opening 142 inside the inner space 101 as schematically shown by arrow 73 in FIGS. 7A and 7B.
[0027] According to the present invention, the orthogonal projection of the curved edge C1 of the second opening 142 onto a plane B (represented by line B-B in the side views of FIG. 4-7) extending parallel to the longitudinal axis L of the pipe 14 and parallel to the rotational axis W of the rotor 2 when the housing 10 surrounds the latter is a segment of curve (see for instance the front views of pipes according to the invention presented in FIG. 4). Additionally, a projection of the second opening 142, in particular of its curved edge C1, onto a plane perpendicular to the plane B and extending parallel to the longitudinal axis L, i.e. perpendicular to the rotational axis W of the rotor 2, comprises either a straight segment S titled with respect to the longitudinal axis L or a concave segment CA with respect to said longitudinal axis L.
[0028] FIG. 4 shows three different preferred embodiments of the second opening 142 for the pipe 14 according to the invention. For each of the three embodiments, a side view is presented on the left and a corresponding front view on the right. In each case, the pipe 14 comprises a straight part surrounding the longitudinal axis L. According to the top and middle embodiments shown in FIG. 4, said straight part directly ends with the second opening 142. According to the embodiment shown at the bottom of FIG. 4, the straight part is coupled at its end with a curved pipe part curved in a direction substantially parallel to the direction of rotation of the rotor 2, said curved pipe part ending then with the second opening 142. For the three embodiments of FIG. 4, a projection (i.e. orthogonal projection) of the curved edge C1 of the second opening 142 onto a plane parallel to the longitudinal axis L and to the rotational axis W (which is also the longitudinal axis along which the housing 10 extends) is a concave segment of curve.
[0029] In each case and as shown in FIG. 8, said second opening 142 comprises at least one curved edge C1 which is a segment of curve extending continuously from a first point P1 to a second point P2 while passing by a point M that is the point of the segment of curve that is the closest to the first opening 141 with respect to the first point P1 and to the second point P2 which are in particular configured for being closer to the rotor 2 compared to the point M (the point M is typically an “extremum” of the segment of curve with respect to a Cartesian coordinate system x,y,z as shown in FIG. 8, wherein the z-axis extends along the longitudinal axis L, and the x- and y-axis define a plane perpendicular to the z-axis), wherein the tangent to the segment of curve at the first point P1 and respectively at the second point P2 makes an angle α1 and respectively α2, with a plane perpendicular to the longitudinal axis L, with α1 and α2 being different from 0. In other words, each of said tangents at P1 and P2 is tilted with respect to said plane perpendicular to the longitudinal axis L of the pipe 14. Preferentially, α1=α2 and the segment of curve (i.e. the curved edge C1) is symmetric with respect to a plane comprising the longitudinal axis L and the point M. Preferably, the segment of curve [P1,M] has the same length as the segment of curve [P2,M]. Preferentially, among all points forming said curved edge C1 extending from P1 to P2 (of course, P1 is different from P2 and M, and P2 is different from M), only the tangent to the segment of curve at the point M is parallel to said plane perpendicular to the longitudinal axis L. The curved edge C1 is thus a continuous segment of curve extending from the first point P1 and from the second point P2, notably symmetrically, to the point M. This continuity of the curved edge C1 improves the stiffness of the second opening 142, so that the thickness of the wall of the pipe 14 can be minimized, sparing therefore material and decreasing the costs of production of the pipe 14.
[0030] Preferentially, in the case wherein the straight part ends directly with said second opening 142, then the curved edge C1 is obtained by truncation of the end of said straight part, i.e. of the pipe straight part, wherein the curved edge C1 corresponds to the intersection of the end of the straight part with an ellipsoid, like a sphere, or with a plane. In other words, a portion of the pipe 14 extending from the end of the straight part until the curved edge C1 has been removed from the pipe 14, creating therefore the opening 142. The curved edge C1 is preferentially obtained by slicing the end of the pipe with a plane or an ellipsoid like a sphere. The result of this truncation is a pipe 14 whose end inside the housing is characterized by the second opening 142 having a beveled shape, e.g. an arched beveled shape. According to this configuration, the curved edge C1 characterizing the beveled end pipe shape is concave. Preferentially, said curved edge C1 connects with a second segment C2 of curve (see FIG. 8), for instance the second curve segment C2 extending from the point P1 to the point P2 in a plane perpendicular to the longitudinal axis L. Said second curve segment C2 is therefore a portion of the second opening 142 that lies in a plane substantially perpendicular to the longitudinal axis. Preferentially, the angles α1 and α2 at respectively the points P1 and P2 defined between the tangent to the curved edge C1 (i.e. the segment of curve “C1”) and the tangent to the second curve segment C2 at both points P1 and P2 are comprised between 90°≤α1, α2≤160°, with preferentially α1 and/or α2 strictly greater than 90°. According to these preferred embodiments, the second opening 142 comprises thus a first portion including the curved edge C1 and a second portion including the second segment of curve C2, wherein the curved edge C1 of the second opening 142 is substantially beveled/tilted with respect to the longitudinal axis L and the segment of curve C2 of said second portion is substantially perpendicular to the longitudinal axis L. According to the preferred embodiments shown at the top and in the middle of FIG. 4 (see also FIG. 5 and FIG. 8), at least one of the following structural constructions might be chosen: [0031] 0.8.Math.Dp1≤Lp1≤1.2.Math.Dp1, wherein Dp1 is the diameter of the pipe straight part and Lp1 is the height of the second opening 142, or of its curved edge C1, as projected onto the longitudinal axis L; and/or [0032] Lp1≤h, wherein h is length of the pipe 14 inside the housing and measured along the longitudinal axis L (see FIG. 5); and/or [0033] r1≥0.5.Math.Dp1, wherein r1 is the radius of a sphere used for the truncation of the end of the straight part as shown in the top embodiment of FIG. 4; and/or [0034] 0.3.Math.Dp1≤x1≤Dp1, with preferentially 0.3.Math.Dp1≤x1≤0.9.Math.Dp1; [0035] 240°≤γ≤90°, wherein γ is the angle characterizing the opening of said second opening 142 measured in the plane perpendicular to the longitudinal axis L, having as vertex the intersection O of said plane with the longitudinal axis L, γ being the angle at vertex O enclosed by the rays OP1 and OP2 (see FIG. 8).
[0036] In the case of the pipe 14 having the straight part coupled at its end with a curved part which makes preferentially the straight part ending by a trumpet/conical shape (see the bottom embodiment in FIG. 4), then said second opening 142 is preferably formed by the open base of a truncated cone 41, wherein the open apex of the cone 41 is coupled to a first extremity of a curved/bent pipe portion 40, wherein the other extremity of said curved/bent pipe portion is connected to the straight part, having both the same diameter, while the diameter Dp2 of the second opening 142 is in this case greater that the pipe diameter Dp1. Preferentially, the truncated cone is centered around a cone axis LC that preferentially forms an angle β with 35°≤β≤90, with preferentially β comprised between 40°-55°. According to this preferred embodiment (shown at the bottom of FIG. 4, in FIG. 6), at least one of the following structural constructions might be chosen: [0037] h≥1.6.Math.Dp1, wherein h is the length of the pipe 14 inside the housing and measured along the longitudinal axis L (see FIG. 6); and/or [0038] Dp1≤Dp2≤2.Math.Dp1; and/or [0039] 0≤Lp2≤1.7.Math.Dp1, wherein Lp2 is the height of the truncated cone 41. If Lp2=0, then the straight part of the pipe 14 is simply connected to the curved portion 40, the second opening having then a diameter equals to Dp1 and making then the angle β with the plane perpendicular to the longitudinal axis L.
[0040] For all embodiments according to the invention, the distance e separating the part of the second opening 142 which is the closest to the rotor 2 from the rotor 2 preferentially satisfies 10 mm≤e≤25 mm.
[0041] Finally, and preferentially, at least one, preferentially each, gas outlet 12 is located radially opposite to the gas inlet 11, e.g. at a bottom part of the housing 10 when the gas inlet is located at a top part of the housing 10. Said gas outlet 12 preferentially comprises an exhaust pipe 21 extending perpendicular to the rotational axis w of the rotor 2 and to the longitudinal axis L of the pipe 14 of the gas inlet 11. The exhaust pipe 21 comprises a first opening located inside the housing and configured for collecting a flow of gas and a second opening configured for exhausting said collected flow of gas outside of the housing 10.
