JP2004197612A - Centrifugal compressor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a centrifugal compressor capable of preventing the efficiency from lowering by preventing leakage of fluid, increasing the operation range at a low flow side, and improving the efficiency at a high flow side. <P>SOLUTION: The centrifugal compressor 10 is provided with a guide vane unit 30 having a guide vane 32 which is slidably inserted in a guide hole 20 formed at a hub side passage wall 15, and can be projected and retreated by means of an operation mechanism 40. In the guide vane unit 30, the guide vane 32 is erected in a diffuser plate 31, and a crown plate 33 is formed at the tip. In a projecting state in the diffuser passage 14, a plane 33B formed outside the crown plate 33 is pneumatically placed in contact with a plane 16B of a shroud side passage wall 16 to make the passage wall at the shroud side. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a centrifugal compressor used for a compressor of a supercharger for a vehicle, and more particularly, to a centrifugal compressor in which guide vanes are provided in a diffuser passage so as to project and retract.
[0002]
[Prior art]
The centrifugal compressor is configured to convert kinetic energy of fluid discharged from the impeller into pressure energy by an annular diffuser passage formed between the impeller and the scroll. In some cases, guide vanes for controlling the flow of a fluid are provided in a diffuser passage to improve the efficiency of energy conversion.
[0003]
Centrifugal compressors with guide vanes in the diffuser passage can improve efficiency in low flow ranges, but have lower efficiency in high flow ranges than those without guide vanes, and the flow range in which high efficiency can be obtained is narrower. Disadvantage. For this reason, in a vehicle turbocharger or the like that requires high efficiency over a wide flow rate range, as disclosed in Patent Documents 1 and 2, guide vanes are provided so as to be able to protrude and retract from a diffuser wall, and guide vanes are provided in a diffuser passage. Various configurations have been proposed that can switch between a protruding state and a state retracted from the diffuser passage. With such a configuration, the efficiency can be increased by projecting the guide blades in a low flow rate range, and the efficiency can be prevented from lowering by retracting the guide blades from the diffuser passage at a high flow rate. High efficiency can be obtained.
[0004]
[Patent Document 1]
JP-A-5-99199 [Patent Document 2]
JP-A-8-254127
[Problems to be solved by the invention]
However, in the centrifugal compressor of the conventional configuration in which the guide vanes as described above are provided so as to be able to protrude and retract from the diffuser wall, the guide vanes protrude and retract through holes having a shape corresponding to the cross-sectional shape of the guide vanes formed on the diffuser wall. Therefore, there is a problem that the fluid leaks through a gap necessary for sliding existing between the hole and the guide blade, and the efficiency is reduced. Further, since a large number of holes having complicated shapes corresponding to the guide blades must be formed, there is a problem that processing is troublesome, time is required, and the cost is increased.
[0006]
The present invention has been made in view of the above-described problems, and can prevent a decrease in efficiency by preventing leakage of a fluid, can increase an operation region on a low flow rate side, and can improve efficiency on a high flow rate side. It is an object to provide a centrifugal compressor.
[0007]
[Means for solving the problem]
A centrifugal compressor according to the present invention that achieves the above object has a guide blade provided on at least one of opposed diffuser walls of a diffuser passage communicating a discharge side of an impeller with a scroll so as to be able to protrude and retract by moving operation means. In the centrifugal compressor, the guide blade is erected on an annular substrate member slidably fitted in an annular guide hole formed in one diffuser wall, and faces the tip of the diffuser when it protrudes. An annular tip plate member is formed, which forms a part of the other diffuser wall to be closed and closes the guide hole at the time of evacuation to form the one diffuser wall. A plane portion orthogonal to the moving direction of the guide blade is formed at least in part, and is configured to be in close contact with the other diffuser wall at the plane portion. And wherein the door.
[0008]
With this configuration, since the board member slides in and out of the guide hole, the shape of the sealing surface of the guide blade is a simple annular shape, so that the guide blade can be easily manufactured and can prevent fluid leakage. Further, when the guide blades are retracted, the end plate member closes the guide hole to prevent leakage of the fluid. Further, when the guide vanes protrude, the flat portion of the tip plate member is in close contact with the other diffuser wall, and flows through the gap formed between the tip plate member and the other diffuser wall to the scroll diffuser inlet side. Prevents reflux.
[0009]
In addition to the above configuration, the tip plate member has the flat portion formed on the outer surface on the outlet side of the diffuser passage, and the inlet side is formed as an inclined surface in a direction in which the tip is sharpened. The inclined surface is configured so as to be smoothly continuous with the one diffuser wall at the time of retreat.
[0010]
With this configuration, when the guide vanes protrude, the flat portion of the tip plate member is in close contact with the other diffuser wall, and the diffuser inlet for the fluid on the scroll side through a gap formed between the tip plate member and the other diffuser wall. When the guide vanes are retracted, the inclined surface of the tip plate member smoothly continues the one diffuser wall to smoothly flow the air flow.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a longitudinal sectional view of a centrifugal compressor of a supercharger for a vehicle which pressurizes and supplies the intake air of an engine, which is one configuration example of the centrifugal compressor according to the present invention, and FIG. FIG. In FIG. 2, the upper half shows a state in which the guide vanes protrude into the diffuser passage, and the lower half shows a state in which the guide vanes retreat from the diffuser passage. FIG. 3 is an enlarged cross-sectional view of a diffuser passage portion indicated by a portion X in FIG. 1 and shows a state where guide vanes protrude into the diffuser passage. FIG. 4 shows a state where the guide vanes are retracted from the state of FIG. FIG.
[0012]
In a centrifugal compressor 10 shown in FIG. 1, an impeller 12 attached to a turbine shaft 9 driven to rotate by a turbine (not shown) is provided in a housing 11, and is formed on a discharge side and an outer peripheral side of the housing 11. The scroll 13 is in communication with the diffuser passage 14.
[0013]
The diffuser passage 14 is an annular passage having a predetermined width sandwiched between opposed hub-side passage walls 15 and a shroud-side passage wall 16 serving as diffuser walls, and the hub-side passage wall 15 is provided between the scroll 13 and the hub side of the scroll 13. The outer cover plate 17 and the inner cover plate 18 are interposed between the body plates 19 fastened to the opening ends, and the shroud-side passage wall 16 is formed by the wall surface of the housing 11.
[0014]
The outer peripheral cover plate 17 and the inner peripheral cover plate 18 constituting the hub side passage wall 15 are each formed in an annular shape having a predetermined thickness and are provided concentrically about the rotation axis of the impeller 12. An annular guide hole 20 is formed in the hub-side passage wall 15 at the inner peripheral edge of the inner periphery 17 and the outer peripheral edge of the inner peripheral cover plate 18. A fluid chamber 41 of an operating mechanism 40 as operating means is formed by the body plate 19 on the back side of the guide hole 20.
[0015]
A guide blade unit 30 including a guide blade 32 is provided in the guide hole 20 so as to be movable in a direction parallel to the rotation axis of the impeller 12. The guide vane unit 30 is moved by an operation mechanism 40 as a moving operation means, and selects one of a protruding state in which the guide vanes 32 are located in the diffuser passage 14 and a retracted state in which the guide vane 32 is retracted from the diffuser passage 14. It can be taken uniformly.
[0016]
In FIG. 3, the guide vane unit 30 has, for example, 13 to 17 guide vanes 32 erected at equal intervals in the circumferential direction on an annular diffuser plate 31 serving as a substrate member, and an annular end serving as a tip plate member at its tip. Is provided. When the guide blade unit 30 protrudes into the diffuser passage 14, the outer surface of the crown plate 33 is in close contact with the shroud-side passage wall 16, and the inner surface serves as a shroud-side passage wall, and the diffuser plate 31 is guided by the guide hole. The opening 20 is closed to form a passage wall on the hub side. In FIG. 4, when the guide blade unit 30 is retracted from the diffuser passage 14, the crown plate 33 closes the guide hole 20 to form a hub-side passage wall.
[0017]
The diffuser plate 31 is formed in an annular shape having a predetermined thickness which is slidably fitted in the guide hole 20, and has a step 31 </ b> A formed inside its outer periphery. On the other hand, a step portion 20A is formed at a corner portion of the outer peripheral cover plate 17 which forms the outer periphery of the guide hole 20, and when the guide blade unit 30 projects, the step portion 31A comes into contact with the step portion 20A and The position is defined and air leakage is prevented. Instead of this, the step formed on the inner periphery of the diffuser plate 31 abuts on the step formed inside the inner periphery of the guide hole 20 to define the position of the guide blade unit 30 and to prevent air leakage. It is good also as composition which prevents.
[0018]
In FIG. 3, the crown plate 33 is an annular shape having an inner and outer diameter capable of closing the guide hole 20 from the diffuser passage 14 side, and an inner surface on the guide blade 32 side is a plane orthogonal to the central axis of the impeller 12. The outer surface of the diffuser passage 14 has a tapered inclined surface 33A on the entrance side and a flat portion 33B on the rear end side. The plane portion 33B is a plane orthogonal to the moving direction of the guide blade 32 and has a predetermined width. As a result, the crown plate 33 has a wedge shape with a sharp tip at the inlet side of the diffuser passage 14 and a plate-like cross section having a predetermined constant thickness at the outlet side. In FIG. 4, when the guide blade unit 30 is retracted from the diffuser passage 14, the sharp tip portion comes into contact with the inner peripheral cover plate 18 to form a smoothly continuous wall surface.
[0019]
On the other hand, a portion of the shroud-side passage wall 16 facing the crown plate 33 is formed in a shape in which the inclined portion 16A and the flat portion 16B are continuous with each other so as to correspond to the outer surface of the crown plate 33. 14, the inclined surface 33A of the crown plate 33 contacts the inclined portion 16A of the shroud-side passage wall 16, and the flat portion 33B of the crown plate 33 contacts the flat portion 16B of the shroud-side passage wall 16, respectively. The inner surface of the crown plate 33 and the housing 11 are smoothly connected.
[0020]
In this manner, the crown plate 33 abuts on the shroud-side passage wall 16 at the inclined surface 33A and the flat portion 33B, whereby the flat portion 33B of the crown plate 33 airtightly adheres to the flat portion 16B of the shroud-side passage wall 16. Thus, it is possible to prevent air from flowing from the scroll side to the inlet side of the diffuser passage 14 through the gap between the crown plate 33 and the shroud-side passage wall 16. That is, when the entire outer surface of the crown plate 33 is inclined, it is difficult to airtightly adhere to the shroud-side passage wall 16 over the entire circumference of the crown plate 33, and the scroll side is formed through a gap formed therebetween. Although air recirculation occurs from the air to the inlet side of the diffuser passage 14 to reduce the efficiency, the provision of the flat portion 33 </ b> B as in the present configuration makes the airtight seal over the entire circumference of the crown plate 33. And the efficiency can be prevented from lowering. Incidentally, an elastic adhesion layer such as rubber may be formed on the outer surface of the crown plate 33 by baking or the like, so that the airtightness can be further improved.
[0021]
In FIGS. 3 and 4, the operating mechanism 40 includes a diaphragm 42 as an elastic partitioning member inside a fluid chamber 41 sealed by the body plate 19 on the back side of the guide hole 20. A projecting spring 43 is disposed in the air chamber 41R on the rear side of the chamber 41F and 41R, and a negative pressure source is provided in the air chamber 41R via a control valve (not shown). Connected and configured.
[0022]
The diaphragm 42 has an annular shape corresponding to the fluid chamber 41, and its center in the width direction is fastened to the diffuser plate 31 of the guide blade unit 30, and is urged forward by a projecting spring 43.
[0023]
The plurality of projecting springs 43 are coil springs, and are disposed in the air chamber 41 </ b> R in the circumferential direction. The projecting springs 43 urge the diaphragm 42 forward through a retainer 44.
[0024]
In the operating mechanism 40 configured as described above, in a normal state, the diaphragm 42 is pressed and urged forward by the projecting spring 43 to bring the guide blade unit 30 into the projecting state, and the control valve is opened to supply the negative pressure source to the air chamber 41R. When the negative pressure is applied, the diaphragm 42 is displaced rearward against the urging force of the protruding spring 43, so that the guide blade unit 30 is set in the retracted state.
[0025]
Here, a ventilation hole 50 that communicates the rear air chamber 41 </ b> R and the diffuser passage 14 is provided through the outer peripheral cover plate 17 and the body plate 19.
[0026]
In the ventilation hole 50, a ventilation hole 51 penetrating the outer peripheral cover plate 17 in the thickness direction and a ventilation hole 52 penetrating the body plate 19 in the thickness direction communicate with each other at a joint surface between the outer peripheral cover plate 17 and the body plate 19. It is formed as follows. The diameter and number thereof are set to a minimum value so that the pressure of the diffuser passage can be applied to the air chamber 41R and the operation of moving the diaphragm 42 by applying a negative pressure from a negative pressure source is not hindered. For example, it may be formed at one location in the circumferential direction with a diameter of 1 mm.
[0027]
By providing such a vent hole 50, the pressure in the diffuser passage 14 acts on the rear air chamber 41R, and the front air chamber 41F in which the pressure in the diffuser passage 14 leaks and the rear air chamber 41R. The chamber 41R and the internal pressure are equalized. As a result, it is possible to stably maintain the protruding state by performing the protruding operation of the guide blade unit 30 with the protruding spring 43 having a small urging force. That is, when there is no vent hole 50, only the pressure in the front air chamber 41F increases and acts on the diaphragm 42. Therefore, the projecting spring 43 for projecting the guide blade unit 30 exerts a large urging force against this pressure. However, it is possible to drive with a small force by eliminating the pressure difference between the front and rear air chambers 41F and 41R by the ventilation hole 50. In this configuration, the opening position of the ventilation hole 50 to the diffuser passage 14 is set to a position covered by the crown plate 33 when the guide blade unit 30 is in the retracted state, but the ventilation hole 50 is hermetically closed and closed. When there is a possibility that the supply of pressure to the air chamber 41R on the side may become impossible, a through hole is formed at a position corresponding to the opening of the ventilation hole 50 of the crown plate 33.
[0028]
The centrifugal compressor 10 configured as described above, with the control valve of the operating mechanism 40 closed in the low flow rate region as shown in FIG. 3, so that the guide blade 32 is positioned in the diffuser passage 14 so that the guide blade unit 30 is projected into the diffuser passage 14. On the other hand, as shown in FIG. 4, in the high flow rate region, the control valve is opened to retract the guide blade unit 30 from the diffuser passage 14. As a result, the efficiency can be increased by the guide blades 32 in the low flow rate region, and the efficiency can be prevented from decreasing in the high flow rate range, so that high efficiency can be obtained in a wide flow rate range.
[0029]
The movement of the guide vane unit 30 is possible only by controlling the opening and closing of one control valve of the operation mechanism 40, and is extremely simple. Since the control valve may be a simple one, it can be constructed at a low cost.
[0030]
In a state where the guide blade unit 30 protrudes into the diffuser passage 14, the diffuser plate 31 closes the guide hole 20, and the step portion 31 A of the diuser plate 31 contacts the step portion 20 A of the guide hole 20, and the inside of the diffuser passage 14. Can be prevented from leaking into the fluid chamber 41, and the diaphragm 42 in the fluid chamber 41 can be kept airtight so that a decrease in efficiency due to air leakage can be prevented. Since the inner surface of the crown plate 33 is smoothly continuous with the casing 11, the air discharged from the impeller 12 can flow smoothly.
[0031]
On the other hand, when the guide vane unit 30 is retracted from the diffuser passage 14, the crown plate 33 closes the guide hole 20 to prevent the air in the diffuser passage 14 from leaking to the fluid chamber 41, and the outer surface of the crown plate 33. Can smoothly flow air discharged from the impeller 12 continuously with the cover plate 18.
[0032]
Although the above configuration example has been described with respect to the centrifugal compressor applied to the vehicle supercharger, the present invention is not limited to the vehicle supercharger, but similarly applies to other centrifugal compressors operating in a wide flow rate range. Can be applied. Further, the guide vanes are provided on the wall surface on the hub side of the diffuser passage, but may be provided on the wall surface on the shroud side if there is sufficient space.
[0033]
【The invention's effect】
As described above, according to the centrifugal compressor according to the present invention, the guide blades stand on the annular substrate member slidably fitted in the annular guide hole formed in one of the diffuser walls. A toroidal tip plate member is provided at the tip thereof, which forms a part of the other diffuser wall facing when protruding and closes the guide hole when retracting to form one diffuser wall, The tip plate member has a flat portion formed on at least a part of the outer surface thereof at right angles to the moving direction of the guide blade, and the flat plate portion is configured to be in close contact with the other diffuser wall, so that the guide blade is Since the substrate member slides in and out of the guide hole, the shape of the sealing surface is a simple annular shape, so that it can be easily manufactured and can prevent a decrease in efficiency due to leakage of fluid. Further, when the guide vanes are retracted, the tip plate member closes the guide hole to prevent a decrease in efficiency due to fluid leakage, and when the guide vanes protrude, the flat portion of the tip plate member is in close contact with the other diffuser wall and the tip plate member contacts the diffuser wall. This prevents the fluid on the scroll side from flowing back to the diffuser inlet side through the gap between the other diffuser walls, thereby achieving high efficiency. That is, it is possible to prevent a decrease in efficiency by preventing leakage of the fluid, to expand an operation region on the low flow rate side, and to improve the efficiency on the high flow rate side.
[0034]
In addition to the above configuration, the end plate member has a flat portion formed on the outer surface on the outlet side of the diffuser passage, and the inlet side is formed as an inclined surface with a sharpened tip, and is inclined when the guide blade is retracted. The surface is configured so as to be smoothly continuous with one diffuser wall, so that when the guide vanes protrude, the flat portion of the tip plate member is in close contact with the other diffuser wall and the tip plate member and the other diffuser wall are in contact with each other. In addition to preventing reflux of the fluid on the scroll side to the diffuser inlet side through the gap formed between the diffuser and the efficiency of the diffuser, the inclined surface of the tip plate member smoothly contacts the one diffuser wall when the guide vanes are retracted. An air stream can be smoothly flowed continuously and high efficiency can be obtained.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a centrifugal compressor of a supercharger for a vehicle, which is a configuration example of a centrifugal compressor according to the present invention, which supplies pressurized intake air to an engine.
FIG. 2 is a partially cutaway sectional view of a casing corresponding to the line AA in FIG. 1 except for a casing.
FIG. 3 is an enlarged cross-sectional view of a portion X in FIG. 1 and shows a state where guide vanes protrude into a diffuser passage.
FIG. 4 is a view showing a state where the guide vanes are retracted from FIG. 3;
[Explanation of symbols]
Reference Signs List 10 Centrifugal compressor 12 Impeller 13 Scroll 14 Diffuser passage 15 Hub-side passage wall (diffuser wall)
16 Shroud side passage wall (diffuser wall)
20 guide hole 30 guide blade unit 31 diffuser plate (substrate member)
32 Guide vane 33 Crown plate (tip plate member)
33A Inclined surface 33B Flat surface portion 40 Operation mechanism (moving operation means)

Claims (2)

In a centrifugal compressor, a guide blade is provided on at least one of the opposed diffuser walls of a diffuser passage communicating with a discharge side of an impeller and a scroll so as to be able to protrude and retract by moving operation means.
The guide vanes are erected on an annular substrate member slidably fitted in an annular guide hole formed in one diffuser wall, and the other diffuser wall is opposed to the distal end thereof when protruding. And a ring-shaped tip plate member that forms a part of the diffuser wall and closes the guide hole when retracted to form the one diffuser wall is provided.
The tip plate member has a flat portion formed on at least a part of its outer surface perpendicular to the moving direction of the guide blade, and the flat plate portion is configured to be in close contact with the other diffuser wall. Characteristic centrifugal compressor. The tip plate member has the flat portion formed on the outer surface on the outlet side of the diffuser passage, and the inlet side is formed as an inclined surface having a sharpened tip, and the inclined surface is formed when the guide blade is retracted. The centrifugal compressor according to claim 1, wherein the centrifugal compressor is configured to be smoothly connected to the one diffuser wall.

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