JP2007309299A - Centrifugal compressor with variable diffuser - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a centrifugal compressor with a variable diffuser capable of surely constituting the variable diffuser of a two-stage blade cascade even when there is not enough installation space for the variable diffuser in the centrifugal compressor. <P>SOLUTION: Respective front blades 10B and respective rear blades 10C are supported on a base plate 9 through a common turning support shaft 10A in such a manner of capable of being turned. When a group of the rotating support shafts 10A are synchronously turned, a group of the front blades 10B and a group of the rear blades 10C are simultaneously varied and operated. A swirling flow of suction gas flowing from a base end outer periphery of a compressor wheel to a scroll flow passage flows along the group of the front blades 10B and the group of the rear blades 10C, and thereby, the velocity of the swirling flow is gradually decelerated in two stages, and a pressure of the suction gas is effectively raised. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a centrifugal compressor that pressurizes and pumps suction gas, and particularly relates to a centrifugal compressor with a variable diffuser including a variable diffuser.

  2. Description of the Related Art Conventionally, a centrifugal compressor that pressurizes sucked gas by pumping gas sucked by a compressor wheel rotating in a compressor housing toward a scroll passage formed around the compressor wheel is generally known.

  As this type of centrifugal compressor, a centrifugal compressor with a variable diffuser (see, for example, Patent Document 1) including a variable diffuser that can variably adjust the pressure of intake air is known. Here, the variable diffuser simultaneously tilts the group of movable blades (blade-type vanes) arranged in a ring via the rotation support shafts to simultaneously adjust the blade angle of each movable blade (wing-type vane). It is a variable diffuser with a single stage cascade that can be changed to

Further, as this type of centrifugal compressor, a centrifugal compressor provided with a two-stage blade row diffuser capable of efficiently increasing the pressure of the suction gas by gradually decelerating the flow velocity of the suction gas in two stages (for example, Patent Documents). 2), and a multistage centrifugal compressor (see, for example, Patent Document 3) in which only the latter blade row of the two-stage blade row is rotatably supported and its blade angle is variable.
JP 2005-163691 A (paragraph number 13, paragraph number 15, FIG. 1, FIG. 2) JP-A-6-241197 (abstract) Japanese Patent Laid-Open No. 2001-200787 (paragraph number 35)

  By the way, the development of centrifugal compressors configured as turbocharger compressors for vehicles has been progressing in the direction of increasing the startup speed of operation, and the operating range from the surging area to the choke area has been expanded accordingly. Is desired.

  In order to meet such a demand, a variable diffuser having a two-stage blade row is configured by combining the structure of the variable diffuser described in Patent Document 1 and the structure of the diffuser having the two-stage blade row described in Patent Document 2. It is possible to do.

  However, in such a variable diffuser having a two-stage blade row, a group of rotating support shafts and a group of rotating support shafts for simultaneously changing the blade angles of the first-stage blade row are rotated synchronously. In addition to the one-system link mechanism to be moved, another group of rotation support shafts corresponding to the second stage blade row and another one-system link mechanism are required.

  Therefore, the variable diffuser of the two-stage blade row is not only complicated in structure but also large in size, increasing the manufacturing cost, and is difficult to apply when there is not enough room for the variable diffuser in the centrifugal compressor. Become.

  Therefore, the present invention provides a centrifugal compressor with a variable diffuser capable of reliably configuring a variable diffuser of a two-stage blade row even when there is not enough space for installing the variable diffuser in the centrifugal compressor. And

  The centrifugal compressor with a variable diffuser according to the present invention receives the incoming air from the vane provided in the diffuser portion of the centrifugal compressor between the outer periphery of the proximal end portion of the compressor wheel in the compressor housing and the scroll passage around the compressor wheel. A centrifugal compressor with a variable diffuser having a variable diffuser whose angle is variable according to the amount of intake air, the variable diffuser including a base plate that forms an annular gas flow path between the compressor housing and a shroud wall surface; A group of movable wings arranged in a ring on the base plate, and a group of rotating support shafts that can pivotably support the movable wings on the base plate and simultaneously change the wing angles of the movable wings. Each movable wing has a combined structure of a front wing and a rear wing divided by a predetermined gap in the blade length direction. Characterized in that the front blades and rear blades are pivotally supported on the base plate via a common rotational shaft.

  In the centrifugal compressor with a variable diffuser according to the present invention, the blade angles of the group of front blades and the group of rear blades constituting the group of movable blades are simultaneously adjusted by the group of rotation support shafts rotating synchronously. Change operation is performed. Then, the swirling flow of the suction gas flowing from the outer periphery of the proximal end portion of the compressor wheel toward the scroll flow path flows along the group of front stage blades and the group of rear stage blades. It is decelerated and the pressure of the intake gas rises efficiently.

  Here, the centrifugal compressor with a variable diffuser of the present invention employs a structure in which each front blade and each rear blade are rotatably supported on a base plate via a common rotation shaft. Compared to the structure in which the front blades and the rear blades are rotatably supported on the base plate via separate rotation shafts, each rotation support shaft and a link mechanism for rotating them synchronously are one system. And the structure is extremely simple.

  In the centrifugal compressor with a variable diffuser according to the present invention, the suction gas flowing along the pressure surface of the front blade is from the gap between the rear end portion of the front blade and the front end portion of the rear blade to the suction surface side of the rear blade. It is preferable that the rear end portion of the front blade and the front end portion of the rear blade are coupled to the rotation support shaft in a state where the positions of the annular gas flow passages are shifted in the radial direction and the circumferential direction so as to flow in.

  In this case, the high-energy intake gas flowing along the pressure surface of the front blade smoothly flows into the suction surface side of the rear blade from the gap between the rear end portion of the front blade and the front end portion of the rear blade. For this reason, even if a separation phenomenon occurs in the suction gas flowing along the suction surface of the front blade, the flow of the separated suction gas flows from the pressure surface of the front blade to the suction surface side of the rear blade. Since it joins the gas flow, the exfoliation phenomenon is prevented from expanding.

  The centrifugal compressor with a variable diffuser according to the present invention employs a structure in which the front blades and the rear blades are rotatably supported on the base plate via the common rotation shafts. The shaft and the link mechanism for rotating them synchronously are only one system, and the structure is extremely simple. Therefore, according to the centrifugal compressor with a variable diffuser of the present invention, the variable diffuser of the two-stage blade row can be reliably configured even when there is no room for the installation of the variable diffuser in the centrifugal compressor.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of a centrifugal compressor with a variable diffuser according to the invention will be described with reference to the drawings. In the drawings to be referred to, FIG. 1 is a sectional view showing a schematic structure of a turbocharger provided with a centrifugal compressor with a variable diffuser according to an embodiment as a compressor, FIG. 2 is a front view of the variable diffuser shown in FIG. FIG. 4 is an enlarged perspective view of the movable blade shown in FIG. 2, and FIG. 4 is a partially enlarged view of the variable diffuser showing the operation of the front blade and the rear blade of the movable blade shown in FIG.

  A centrifugal compressor with a variable diffuser according to an embodiment is configured as a compressor of a turbocharger 1 shown in FIG. The turbocharger 1 connects a turbine housing 2 for a turbine interposed in the middle of an exhaust system of a vehicle engine (not shown) and a compressor housing 3 for a compressor interposed in the middle of an intake system. A center housing (bearing housing) 4 is provided.

  In the turbine housing 2, a scroll passage 2 </ b> A for introducing exhaust gas flowing through the exhaust system of the vehicle engine is formed. A turbine wheel 5 that is rotationally driven by passage of exhaust gas flowing in from the scroll flow path 2 </ b> A is accommodated in the turbine housing 2.

  On the other hand, the compressor housing 3 accommodates a compressor wheel 6 for supercharging the intake air of the vehicle engine to a pressure higher than the atmospheric pressure. Around the compressor wheel 6, there is formed a scroll passage 3A that pressurizes the intake air and feeds it to the intake system of the vehicle engine.

  The turbine wheel 5 in the turbine housing 2 and the compressor wheel 6 in the compressor housing 3 are connected to each other via a shaft 7 so as to rotate integrally. The shaft 7 is rotatably supported by the center housing 4 via a floating bearing (not shown).

  Here, between the outer periphery of the proximal end portion of the compressor wheel 6 in the compressor housing 3 and the scroll flow path 3A around the compressor wheel 3, the angle of attack with respect to the inflow air of the vane provided in the diffuser portion of the centrifugal compressor is set as the intake air amount. A variable diffuser 8 having a two-stage blade row that is variable according to the above is installed.

  The variable diffuser 8 is a flat ring-shaped base plate 9 that is fitted and fixed to the center housing 4 side in the compressor housing 3 to form an annular air flow path with the shroud wall surface 3B of the compressor housing 3, and FIG. As shown in FIG. 4, a group of movable blades 10 arranged concentrically and annularly on the base plate 9 at equal angular intervals, and each movable blade 10 is supported on the base plate 9 so as to be rotatable while passing through the base plate 9. A group of rotating support shafts 10A capable of changing the blade angles of the movable blades 10 all at once are provided.

  Here, as shown in an enlarged view in FIG. 3, each movable blade 10 has a combined structure of a front blade 10 </ b> B and a rear blade 10 </ b> C divided with a predetermined gap in the blade length direction. The front blade 10B and the rear blade 10C are integrally formed with the rotary shaft 10A, for example, by casting an aluminum alloy. The rotating support shaft 10A is formed in a cylindrical shape, and a disk-like platform 10D having a slightly larger diameter is formed at one end thereof.

  The front blade 10B has a wedge shape in which a leading edge 10E at the front end facing the upstream side of the intake air flowing along the blade length direction is formed at an acute angle, and a trailing edge 10F at the rear end is formed in an arc shape. It has a cross-sectional shape.

  Similarly, in the rear blade 10C, the leading edge 10G at the front end facing the upstream side of the intake air flowing along the blade length direction is formed at an acute angle, and the trailing edge 10H at the rear end is formed in an arc shape. It has a wedge-shaped cross-sectional shape. The rear blade 1 is formed in a cross-sectional shape larger than that of the front blade 10B so as to constitute the movable blade 10 in combination with the front blade 10B.

  Then, the front blade 10B and the rear blade 10C as described above cancel the moments input to the rotary shaft 10A via the front blade 10B and the rear blade 10C by the pressure of the intake air, respectively. In order to enable smooth rotation with respect to the base plate 9, the rear end portion of the front blade 10B on the trailing edge 10F side and the front end portion of the rear blade 10C on the leading edge 10G side are one end of the rotation support shaft 10A. Is coupled to the end face of the platform 10D.

  Also, as shown by the arrows in FIG. 4, the intake air flowing along the pressure surface of the front blade 10B is between the trailing edge 10F at the rear end of the front blade 10B and the leading edge 10G at the front end of the rear blade 10C. In order to flow from the gap to the suction surface side of the rear blade 10C, the trailing edge 10F side rear end of the front blade 10B and the leading edge 10G side front end of the rear blade 10C are annular airflows. The position is shifted in the radial direction and the circumferential direction of the road.

  That is, the front stage blade 10B is disposed close to the inner side of the base plate 9 with respect to the center line of the rear stage blade 10C, and the rear end portion of the front stage blade 10B on the trailing edge 10F side is the leading edge 10G side of the rear stage blade 10C. The base plate 9 is disposed with a position shifted inward in the radial direction of the base plate 9 and is shifted in the circumferential direction of the base plate 9 toward the upstream side of the intake air.

  On the other hand, as shown in FIG. 1, in order to simultaneously tilt the front blades 10B to equal blade angles and rotate the rear blades 10C to equal blade angles via the pivot shaft 10A, as shown in FIG. On the back side of the base plate 9, a unison ring 12 that is rotatably supported concentrically on the base plate 9 via a plurality of guide rollers 11 is disposed.

  The unison ring 12 is engaged with a swinging end portion of each operation arm (not shown) fixed to the other end portion of each rotation support shaft 10 </ b> A that penetrates the base plate 9. When the unison ring 12 is rotated through the link mechanism 13 by, for example, a drive motor (not shown) attached to the compressor housing 3, the unison ring 12 is rotated through the respective operation arms (not shown). By rotating 10A all at once, the front blades 10B are simultaneously tilted to an equal blade angle, and the subsequent blades 10C are simultaneously tilted to an equal blade angle.

  In the turbocharger 1 configured as described above, exhaust gas discharged to the exhaust system of the vehicle engine (not shown) passes through the turbine wheel 5 from the scroll flow path 2A in the turbine housing 2 shown in FIG. As a result, the turbine wheel 5 is rotationally driven. The rotation of the turbine wheel 5 causes the compressor wheel 6 in the compressor housing 3 to be rotationally driven, whereby the air in the intake system of the vehicle engine is pressurized to atmospheric pressure or higher and fed from the scroll flow path 3A. .

  Here, the intake air that is pumped from the outer periphery of the base end portion of the compressor wheel 6 toward the scroll passage 3 </ b> A is formed between the base plate 9 of the variable diffuser 8 and the shroud wall surface 3 </ b> B of the compressor housing 3. By circulating the annular air flow path along the front blades 10B and the rear blades 10C of the variable diffuser 8, the flow velocity is gradually decreased in two stages by the front blades 10B and the rear blades 10C, thereby improving the pressure efficiency. It rises gradually gradually.

  At that time, as shown by the arrows in FIG. 4, the high-energy intake air flowing along the pressure surface of the front blade 10B is the leading edge of the trailing edge 10F of the rear blade 10B and the leading edge of the front blade 10C. It flows into the suction surface side of the rear blade 10C from the gap between the edge 10G.

  For this reason, even if a separation phenomenon occurs in the intake air flowing along the suction surface of each front blade 10B in a state where the blade angle of the group of movable blades 10 is operated to be small and the flow rate of the intake air is reduced, The separated intake air flow merges with the flow of high energy intake air flowing from the pressure surface of each front blade 10B to the suction surface side of each rear blade 10C, so that the separation phenomenon is prevented from expanding.

  Here, the centrifugal compressor with a variable diffuser according to an embodiment employs a structure in which the front blades 10B and the rear blades 10C are rotatably supported on the base plate 9 via the common rotation shafts 10A. Therefore, each rotation support shaft 10A and the unison ring 12 and the link mechanism 13 that rotate these synchronously are only one system, and the structure is extremely simple.

  Therefore, according to the centrifugal compressor with a variable diffuser of the embodiment configured as a compressor of the turbocharger 1, the variable diffuser of the two-stage blade row can be used even when there is not enough room for the variable diffuser in the compressor housing 3. 8 can be configured reliably.

  The centrifugal compressor with a variable diffuser according to the present invention is not limited to the above-described embodiment. For example, the shapes of the front blade 10B and the rear blade 10C constituting the movable blade 10 shown in FIG. 3 are not limited to those shown in the drawing, and can be changed as appropriate.

  Further, the front blade 10B and the rear blade 10C do not need to be integrally formed with the rotating support shaft 10A by casting an aluminum alloy, and may be integrally formed with an appropriate structural synthetic resin or the like.

  Furthermore, the front blade 10B and the rear blade 10C may be fixed to the pivot shaft 10A by appropriate means such as welding or adhesion.

It is sectional drawing which shows schematic structure of the turbocharger provided with the centrifugal compressor with a variable diffuser which concerns on one Embodiment of this invention as a compressor. It is a front view of the variable diffuser shown in FIG. FIG. 3 is an enlarged perspective view of the movable wing shown in FIG. 2. FIG. 3 is a partially enlarged view of a variable diffuser showing the operation of the front blade and the rear blade of the movable blade shown in FIG. 2.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Turbocharger, 2 ... Turbine housing, 3 ... Compressor housing, 3A ... Scroll flow path, 3B ... Shroud wall surface, 5 ... Turbine wheel, 6 ... Compressor wheel, 8 ... Variable diffuser, 9 ... Base plate, 10 ... Movable blade, 10A: Rotating support shaft, 10B: Front blade, 10C: Rear blade, 10D ... Platform, 10E ... Leading edge, 10F ... Trailing edge, 10G ... Leading edge, 10H ... Trailing edge, 11 ... Guide roller, 12 ... Unison ring, 13 ... Link mechanism.

Claims (2)

Variable angle of change of the angle of attack with respect to the inflow air of the vane provided in the diffuser part of the centrifugal compressor between the outer periphery of the base end of the compressor wheel in the compressor housing and the scroll flow path around it. A centrifugal compressor with a variable diffuser equipped with a diffuser,
The variable diffuser has a base plate that forms an annular gas flow path with a shroud wall of the compressor housing, a group of movable blades arranged in an annular shape on the base plate, and each movable blade can be rotated on the base plate. And a group of pivots that can be operated to change the blade angle of each movable wing at once,
Each of the movable blades has a combined structure of a front blade and a rear blade divided by a predetermined gap in the blade length direction, and the rotating support shaft common to the front blade and the rear blade. A centrifugal compressor with a variable diffuser, which is rotatably supported on the base plate via   The rear end of the front blade and the rear stage so that the intake gas flowing along the pressure surface of the front blade flows into the suction surface side of the rear blade from the gap between the rear end of the front blade and the front end of the rear blade. 2. The centrifugal with variable diffuser according to claim 1, wherein a front end portion of the blade is coupled to the rotation support shaft in a state where the position of the annular gas flow path is shifted in a radial direction and a circumferential direction. Compressor.