JP2001329995A - Centrifugal compressor with variable diffuser - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a centrifugal compressor with a variable diffuser capable of completely burying a guide blade in a diffuser part, completely preventing a leak of compressed fluid from a gap between the guide blade and a diffuser wall, and suppressing drop in efficiency. SOLUTION: This centrifugal compressor has the guide blade 12 coming in and out of the diffuser wall 11; a hollow air-chamber 13; an elastic partition member 14 air tightly dividing the air-chamber and movable in the axial direction; and a fluid driving mechanism generating pressure difference in the elastic partition member and moving the elastic partition member in the axial direction by the fluid pressure. A part of the guide blade is fixed to the elastic partition member. A gap flow reducing device for reducing gap flow flowing between the diffuser wall for housing the guide blade and the guide blade is installed. The gap flow reducing device is composed of plural projections 21 for connecting a fixed part of an adjacent blade part 12b of a blade base part 12a; and recessed grooves 22 for housing the plural projections installed in the diffuser wall for housing the guide blade without contact.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a centrifugal compressor with a variable diffuser, which allows guide vanes to protrude and retract from a diffuser.

[0002]

2. Description of the Related Art A diffuser portion, which is a ring-shaped flow path, is provided between an impeller of a centrifugal compressor and a scroll portion. The diffuser has a role of converting kinetic energy of fluid discharged from the impeller into pressure.

[0003] A centrifugal compressor in which a guide vane for controlling the flow of a fluid is provided in the diffuser is also widely known. Providing such guide vanes generally increases efficiency over the "bladeless" case, but the usable flow range is narrower than without vanes. Therefore, when the flow rate range is very wide, such as in a centrifugal compressor applied to a vehicle supercharger, it is necessary to always change the characteristics of the diffuser to obtain characteristics that are close to optimal.

[0004] In response to this demand, as means for changing the characteristics of the diffuser section, there have conventionally been (1) means for changing the mounting angle of the diffuser blade (so-called variable pitch mechanism).
Also, (2) means for changing the width of the diffuser wall surface (for example, Japanese Patent Application Laid-Open No. 4-47199) has been proposed and partially implemented. However, since the structure of the variable pitch mechanism is complicated, a small centrifugal compressor (for example, a supercharger for a passenger car) is used.
Was difficult to apply. Further, in the means for changing the width of the diffuser wall surface (Japanese Patent Laid-Open No. 4-47199), there is a problem that the step in the flow path is inevitable and the performance is greatly reduced.

On the other hand, as means which have less of these problems, have a relatively simple structure, and have a great merit in performance, means for protruding and retracting the blades of the diffuser portion have been proposed (for example, Japanese Patent Laid-Open No. 5-99199, Kaihei 8-25412
No. 7).

[0006] "Centrifugal compressor" in JP-A-5-99199
As shown in FIG. 6, a blade device including a blade 2 having a large chord length and a blade 3 having a small chord is arranged on the inner peripheral side of the stationary blade 1, and the blade device increases in accordance with the operating flow rate of the compressor. The blade 2 or the small blade 3 protrudes into the diffuser flow path. Also, Japanese Patent Application Laid-Open No. 8-254127 discloses a "supercharging device".
As shown in FIG. 7, the guide vanes 4 are provided in the diffuser portion so as to be able to project and retract, the actuator 5 causes the guide vanes to project or retract into the diffuser portion, and the actuator operates in response to the operating state of the engine. It has a controller to perform.

[0007]

In the centrifugal compressor shown in FIG. 6, the stationary blade 1 is always provided in the diffuser portion.
Even if the large and small blades 2 and 3 are made to protrude, there is a problem in that the "bladeless" characteristic applicable to a wide flow rate range cannot be obtained. Further, in the supercharging device shown in FIG. 7, the guide blades can be completely projected and retracted into the diffuser portion in principle, but (1) it is difficult or impossible to keep the space between the guide blades and the diffuser portion airtight. It is possible to prevent leakage of the pressurized fluid completely, and (2) the actuator 5 operates against the pressurized internal pressure of the diffuser portion, so that the actuator becomes large. Was.

Furthermore, when the guide blades are made to be able to protrude and retract, it is necessary that the blade tips come into complete contact with the opposing wall when the blades are protruded from the viewpoint of improving efficiency. In this case, a small gap is required between the base of the blade and the diffuser wall in consideration of the processing accuracy and the assembly accuracy of the product.
However, if this gap exists, a gap flow flows from the outlet side of the diffuser with a high pressure to the inlet side of the diffuser through the gap, which causes a problem that the efficiency is reduced.

The present invention has been made to solve such a problem. That is, an object of the present invention is to allow the guide blade to completely protrude and retract from the diffuser portion, to completely prevent the pressurized fluid from leaking from the gap between the guide blade and the diffuser wall, and to set the guide blade to the opposite side when the guide blade projects. The blade tip gap loss can be reduced by closely adhering to the diffuser wall of the
At the same time, it is an object of the present invention to provide a centrifugal compressor with a variable diffuser, which can reduce a gap flow flowing to the inlet side of the diffuser through a gap between the base of the guide vane and the diffuser wall surface, and can suppress a decrease in efficiency.

[0010]

According to the present invention, there is provided a guide blade (12) which can protrude and retract from at least one of opposed diffuser walls (11), and a hollow provided on the diffuser wall side for accommodating the guide blade. An air chamber (13), an elastic partition member (14) which air-tightly divides the air chamber into a diffuser side and an anti-diffuser side and is movable in the axial direction, and a diffuser side and an anti-diffuser side of the elastic partition member. A fluid drive mechanism for generating a differential pressure to move the elastic partition member in the axial direction by fluid pressure, wherein a part of the guide blade is attached to the elastic partition member, and further a diffuser wall for accommodating the guide blade. A centrifugal compressor with a variable diffuser, comprising: a gap flow reducing device that reduces a gap flow flowing between the guide blades.

According to the configuration of the present invention described above, there is provided the elastic partition member (14) for airtightly dividing the hollow air chamber (13) accommodating the guide vane (12) into the diffuser side and the anti-diffuser side. Therefore, leakage of the pressurized fluid from the gap between the guide vane and the diffuser wall can be completely prevented. Further, since the elastic partition member is moved in the axial direction by the fluid pressure by the fluid drive mechanism, the guide blade is brought into close contact with the diffuser wall surface on the opposite side when the guide blade protrudes, so that blade tip gap loss can be reduced.

In addition, since a gap flow reducing device for reducing a gap flow flowing between the diffuser wall for accommodating the guide blade and the guide blade is provided, a high pressure is applied through the gap between the base of the blade and the diffuser wall surface. It is possible to reduce the gap flow flowing from the outlet side of the diffuser to the inlet side of the diffuser, thereby suppressing a decrease in efficiency.

According to a preferred embodiment of the present invention, the guide blade (12) includes a disk-shaped blade base (12a),
The gap flow reduction device comprises a plurality of blades (12b) fixed at one end to the blade base and arranged at intervals in the circumferential direction, and the gap flow reducing device is configured to fix a blade adjacent to the blade base (12a). And a plurality of concave grooves (22) provided on a diffuser wall for accommodating the guide vanes and accommodating the plurality of convexes without contact. With this configuration, the protrusion (2) of the blade base (12a)
A so-called labyrinth seal can be constituted by 1) and the concave groove (22) of the diffuser wall, and the gap flow can be reduced without making them contact each other.

Further, the convex portion (21) and the concave groove (22)
May extend in the circumferential direction or obliquely to the circumferential direction. According to any of these configurations, the labyrinth seal can be formed substantially perpendicular to the gap flow flowing from the outlet side of the diffuser having a high pressure to the inlet side of the diffuser, and the gap flow can be effectively reduced.

Further, the clearance flow reducing device may be a brush seal or an elastic seal provided between the guide blade and a through hole in a diffuser wall for accommodating the guide blade.
By using such a brush seal or an elastic seal together, the flow rate of the fluid flowing into the labyrinth seal portion can be further reduced.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. In each of the drawings, common portions are denoted by the same reference numerals, and redundant description will be omitted. FIG. 1 is an overall configuration diagram showing a centrifugal compressor with a variable diffuser of the present invention. As shown in this figure, the centrifugal compressor 10 with a variable diffuser of the present invention accommodates a guide blade 12 that can protrude and retract from at least one of the opposed diffuser walls 11 (in this figure, the anti-shroud side) and a guide blade 12. The air chamber 13 includes a hollow air chamber 13 provided on the diffuser wall side, and an elastic partition member 14 that divides the air chamber 13 into a diffuser side and a non-diffuser side in an airtight manner and is movable in the axial direction. In this figure, 6 is an impeller, 7 is a scroll casing, and 8 is a seal plate. In this example, the seal plate 8 includes a seal plate cover 8a, a diaphragm cover 8b, and a main body 8c.
Consists of

FIG. 2 is a view taken in the direction of arrows AA in FIG. In this figure, the impeller 6 and the scroll casing 7 are
It is omitted for clarity of the drawing.

As shown in FIG. 1 and FIG.
In this example, is composed of a disk-shaped blade base 12a and a plurality of blades 12b having one end fixed to the blade base 12a and arranged at intervals in the circumferential direction. The diffuser wall 11 on the anti-shroud side (that is, the seal plate cover 8a) is provided with a through hole through which each blade 12b penetrates, and the blade 12b is connected to the diffuser wall 1 on the anti-shroud side.
The blade portion 12b can move in the axial direction of the impeller 6 from a position where the blade portion 12b is retracted flush with the inside 1 to a protruding position where the blade portion 12b abuts on the diffuser wall 11 on the opposite side.

In this example, the hollow air chamber 13 is a hollow cylindrical space provided inside the diffuser wall 11 on the side opposite to the shroud, that is, inside the seal plate 8. The elastic partition member 14 is a ring-shaped diaphragm or bellows, and its outer edge and inner edge are air-tightly fixed to the air chamber 13, and this space (air chamber 13) is divided into a diffuser side and an anti-diffuser side. are doing. Furthermore, this diaphragm (or bellows) can be deformed in the axial direction while maintaining airtightness, and the guide blade 12
(In this example, the left end of the blade base 12a) is attached.

The centrifugal compressor 10 with a variable diffuser according to the present invention further includes a fluid drive mechanism for moving the elastic partition member 14 in the axial direction by fluid pressure. This fluid drive mechanism includes an urging means 16 for urging the elastic partition member 14 in the axial direction, a piping line 17a for reducing or increasing the pressure on the side opposite to the diffuser of the air chamber 13 and an external negative pressure source (or positive pressure). And an on-off valve (not shown) that communicates with the pressure source. A differential pressure is generated between the diffuser side and the anti-diffuser side of the elastic partition member 14 to move the elastic partition member 14 in the axial direction by fluid pressure. In addition, 17b is another piping line for extracting the static pressure of the diffuser portion.

In this example, the urging means 16 is a compression spring housed in a compressed state on the side opposite to the diffuser (left side in the figure) of the air chamber 13, and the elastic partition member 14 and the guide blade 12 via this. It is urged toward the diffuser wall opposite the diffuser section.

According to the above-described structure, for example, when the flow rate of the centrifugal compressor is small and the efficiency needs to be increased, the diffuser side and the anti-diffuser side of the air chamber 13 are communicated with each other to have the same pressure. By the urging force of the means 16, the guide vanes 12 are moved toward the opposite diffuser wall,
The leading end (right end in the figure) of the guide blade 12 can be brought into contact with the diffuser wall on the opposite side without any gap.

Conversely, when the flow rate of the centrifugal compressor is large and its operation is required to be more stable than efficiency, the anti-diffuser side of the air chamber 13 is connected to an external negative pressure source (for example, a vacuum source for brake). , The pressure on the diffuser side (the right side in the figure) of the elastic partition member 14 becomes higher than the pressure on the anti-diffuser side (the left side).
The elastic partition member 14 and the guide blade 12 attached thereto are moved in the opposite direction (left side in the figure) against the urging force of the above, and the guide blade 12 is retracted, and its tip (right end in the figure) is connected to the diffuser wall 11. Can be flush.

FIG. 3 is a schematic configuration diagram of a portion B in FIG. As shown in this figure, the centrifugal compressor 10 with a variable diffuser of the present invention further includes a gap flow flowing between the diffuser wall 11 (that is, the seal plate cover 8a in this example) for accommodating the guide blade 12 and the guide blade 12. And a gap flow reducing device for reducing the gap flow. In the example of FIG. 3, the gap flow reducing device includes a plurality of convex portions 21 that connect fixed portions of adjacent blade portions of the blade base portion 12 a, and a diffuser wall 11 (the seal plate cover 8) that accommodates the guide blade 12.
a) a plurality of grooves 22 provided in FIG. Convex part 21
And the concave groove 22 are fitted without contacting each other,
During this time, a so-called labyrinth seal is formed.

FIG. 4 is a view taken in the direction of arrows CC in FIG. In this figure, in addition to the impeller 6 and the scroll casing 7, a diffuser wall 11 (seal plate cover 8a)
Are omitted, and the disk-shaped blade base 12a and the plurality of blades 12
Only b is shown. As shown in this figure, in this embodiment, the convex portion 21 and the (not-shown concave groove 22) are formed concentrically with the impeller 6 in the circumferential direction.

FIG. 5 is another embodiment similar to FIG. In this embodiment, unlike FIG. 4, the protrusion 21 and the (not-shown concave groove 22) extend obliquely with respect to the circumferential direction concentric with the impeller 6.

According to the configuration of the present invention described above, since the elastic partition member 14 for airtightly dividing the hollow air chamber 13 accommodating the guide blades 12 into the diffuser side and the anti-diffuser side is provided, Leakage of the pressurized fluid from the gap in the diffuser wall can be completely prevented. Further, since the elastic partition member is moved in the axial direction by the fluid pressure by the fluid drive mechanism, the guide blade is brought into close contact with the diffuser wall surface on the opposite side when the guide blade protrudes, so that blade tip gap loss can be reduced.

Further, since a gap flow reducing device for reducing a gap flow flowing between the diffuser wall for accommodating the guide blade and the guide blade is provided, a high pressure is applied through the gap between the base of the blade and the diffuser wall surface. It is possible to reduce the gap flow flowing from the outlet side of the diffuser to the inlet side of the diffuser, thereby suppressing a decrease in efficiency.

In particular, by forming a so-called labyrinth seal with the convex portion 21 of the blade base 12a and the concave groove 22 of the diffuser wall, it is possible to reduce the gap flow without contacting each other.

As a clearance flow reducing device, a brush seal or an elastic seal may be provided between the guide blade and a through hole in the diffuser wall for accommodating the guide blade. By using such a brush seal or an elastic seal together, the flow rate of the fluid flowing into the labyrinth seal portion can be further reduced.

[0031]

According to the centrifugal compressor with a variable diffuser of the present invention described above, the space 13 is provided in a state where the blades come out.
3 can be minimized from the side B to the side A in FIG. That is, the convex portion 2
By forming a so-called labyrinth seal with the groove 1 and the groove 22, the flow path resistance to the air flowing through the gap is increased, and the gap flow (B → C → A in FIG. 3) flowing backward is reduced.
The efficiency of the diffuser can be improved.

Therefore, in the centrifugal compressor with a variable diffuser according to the present invention, the guide vanes can be completely protruded and retracted from the diffuser portion, the leakage of the pressurized fluid from the gap between the guide vanes and the diffuser wall can be completely prevented, and the guide vanes can be completely prevented. When the blades protrude, the guide vanes are brought into close contact with the diffuser wall on the opposite side to reduce blade tip gap loss. It has excellent effects such as the ability to suppress the decrease.

It should be noted that the present invention is not limited to the above-described embodiment, and can be freely modified without departing from the gist of the present invention.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram showing a centrifugal compressor with a variable diffuser of the present invention.

FIG. 2 is a view as viewed in the direction of arrows AA in FIG. 1;

FIG. 3 is a schematic configuration diagram of a portion B in FIG. 1;

FIG. 4 is a view taken in the direction of arrows CC in FIG. 1;

FIG. 5 is another embodiment similar to FIG.

FIG. 6 is a schematic view of a conventional centrifugal compressor with a variable diffuser.

FIG. 7 is another schematic diagram of a conventional centrifugal compressor with a variable diffuser.

[Explanation of symbols]

1 stationary blade, 2, 3 blade, 4 guide blade, 5 actuator, 6 impeller, 7 scroll casing,
8 Seal plate, 8a Seal plate cover, 8
b Diaphragm cover, 8c Main body 10 Centrifugal compressor with variable diffuser, 11 Diffuser wall, 12 Guide vane, 12a Blade base, 12b
Blade part, 13 air chamber, 14 elastic partition member (diaphragm or bellows), 16 urging means (compression spring), 17a, 17b piping line, 21 convex part, 22
Groove

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Hiroshi Tange 3-1-1-15 Toyosu, Koto-ku, Tokyo Ishikawajima Harima Heavy Industries, Ltd. Tokyo Engineering Center (72) Inventor Yoshiaki Hirai 3-1-1 Toyosu, Koto-ku, Tokyo No. 15 Ishikawajima Harima Heavy Industries, Ltd. Tokyo Engineering Center F term (reference) 3H034 AA02 BB03 BB06 DD07 DD08 DD26 EE08 EE13 EE18

Claims (4)

[Claims] 1. A guide vane (12) that can protrude and retract from at least one of the opposed diffuser walls (11), a hollow air chamber (13) provided on the diffuser wall side for accommodating the guide vanes, and An elastic partition member (14) which divides the chamber into a diffuser side and an anti-diffuser side in an airtight manner and is movable in the axial direction, and a differential pressure is generated between the diffuser side and the anti-diffuser side of the elastic partition member to separate the elastic partition member. A fluid drive mechanism for moving in the axial direction by fluid pressure, a part of the guide blade is attached to an elastic partition member, and further, a gap flow flowing between the diffuser wall accommodating the guide blade and the guide blade is provided. A centrifugal compressor with a variable diffuser, comprising a clearance flow reducing device for reducing the amount of clearance. 2. The guide blade (12) includes a disk-shaped blade base (12a) and a plurality of blades (12b) having one end fixed to the blade base and arranged at intervals in the circumferential direction. A plurality of projections (21) connecting fixed portions of adjacent blades of the blade base (12a);
A plurality of grooves (2) provided on a diffuser wall for accommodating the guide vanes and accommodating the plurality of projections without contact.
2. The centrifugal compressor with a variable diffuser according to claim 1, wherein the centrifugal compressor has a variable diffuser. 3. The convex portion (21) and the concave groove (22)
3. The centrifugal compressor with a variable diffuser according to claim 2, wherein the centrifugal compressor with a variable diffuser extends in a circumferential direction or obliquely to the circumferential direction. 4. The device according to claim 1, wherein the clearance flow reducing device is a brush seal or an elastic seal provided between the guide blade and a through hole of a diffuser wall that accommodates the guide blade. Centrifugal compressor with variable diffuser.