JP5796302B2 - Variable nozzle unit and variable capacity turbocharger - Google Patents

Description

  The present invention relates to a variable nozzle unit or the like that varies a flow passage area (flow rate) of exhaust gas supplied to a turbine impeller side in a variable capacity supercharger.

  In recent years, various developments have been made on variable nozzle units used in turbines of variable capacity turbochargers. The configuration of a general variable nozzle unit will be briefly described as follows.

  A general variable nozzle unit includes a shroud as a first base ring that covers a turbine impeller, and a plurality of first guide holes are formed in the shroud at equal intervals in the circumferential direction. In addition, a gap adjusting plate as a second base ring is integrally connected to the shroud via a plurality of connecting pins so as to be opposed to and separated from each other, and the plurality of second guide holes are circumferentially connected to the gap adjusting plate. It is formed at equal intervals in the direction.

  A plurality of variable nozzles are arranged at equal intervals in the circumferential direction between the shroud and the gap adjusting plate, and each variable nozzle can rotate around an axis parallel to the axis of the turbine impeller. In addition, one side surface of each variable nozzle can slide on the facing surface of the shroud, and the other side surface of each variable nozzle can slide on the facing surface of the gap adjusting plate. Further, a first nozzle shaft is integrally formed on one side surface of each variable nozzle, and the first nozzle shaft is rotatably supported in a corresponding first guide hole of the shroud. Similarly, on the other side of each variable nozzle, a second nozzle shaft is integrally formed concentrically with the first nozzle shaft, and the first nozzle shaft can rotate in a corresponding second guide hole of the gap adjustment plate. It is supported by. A rotation mechanism is provided at an appropriate position on the shroud side to rotate the plurality of variable nozzles in synchronization with the opening direction and the narrowing direction (closing direction).

  In addition, there exist some which are shown to patent document 1-patent document 3 as a prior art relevant to this invention.

JP 2009-144615 A JP 2006-258108 A Japanese Patent Laid-Open No. 2007-40251

  By the way, the nozzle side gap of the variable nozzle unit (specifically, the gap between the facing surface of the shroud and one side surface of the variable nozzle and the gap between the facing surface of the gap adjusting plate and the other side surface of the variable nozzle). It is known that the efficiency of the variable capacity supercharger (turbine efficiency) is increased as the value of is reduced. On the other hand, when the nozzle side gap of the variable nozzle unit is reduced, the sliding resistance between the facing surface of the shroud and one side surface of the variable nozzle, and the sliding between the facing surface of the gap adjusting plate and the other side surface of the variable nozzle. Resistance increases. For this reason, the same nozzle opening (when the plurality of variable nozzles are rotated synchronously in the opening direction (opening operation) and when the plurality of variable nozzles are rotated synchronously (in the closing direction) (in the closing operation) Turbine rotational speed difference (turbine rotational speed hysteresis) occurs at the opening of the plurality of variable nozzles, and it becomes difficult to ensure the control performance of the variable capacity supercharger to a high level.

  Therefore, an object of the present invention is to provide a variable nozzle unit having a novel configuration that can solve the above-described problems.

A first aspect of the present invention is a variable nozzle unit that varies the flow area (flow rate) of exhaust gas supplied to a turbine impeller side in a variable capacity supercharger, and is integrally connected in a state of being opposed to each other at least. A pair of base rings each having a plurality of guide holes formed at equal intervals in the circumferential direction, and disposed between the pair of base rings at equal intervals in the circumferential direction and parallel to the axis of the turbine impeller At least one of which can be rotated around an axis, one side surface can slide on the facing surface of one of the base rings, and the other side surface can slide on the facing surface of the other base ring. A plurality of variable nozzles having a nozzle shaft that is integrally formed on a side surface and rotatably supported in the corresponding guide hole, and a plurality of the variable nozzles are synchronized in the opening direction and the narrowing direction (closing direction). A rotating mechanism (synchronous rotating mechanism) for rotating, a facing surface of each base ring (a facing surface of one base ring, a facing surface of the other base ring), one side surface of each variable nozzle, and each While the other side surface of the variable nozzle is subjected to nitriding treatment , the inner peripheral surface of each guide hole is not subjected to nitriding treatment.

According to the first aspect of the present invention , when the flow rate of the exhaust gas is small (in other words, when the engine speed is in the low speed range), the rotation mechanism rotates in synchronization with the direction in which the plurality of variable nozzles are throttled Let As a result, the gas passage area of the exhaust gas supplied to the turbine impeller side (the throat area of the turbine impeller) is reduced, the flow rate of the exhaust gas is increased, and the work amount of the turbine impeller is sufficiently secured. .

  Further, when the flow rate of the exhaust gas is large (in other words, when the engine speed is in a high speed range), the rotation mechanism rotates the plurality of variable nozzles in synchronization with each other in the opening direction. Thereby, the gas flow passage area of the exhaust gas supplied to the turbine impeller side is increased, and a large amount of exhaust gas is supplied (normal operation of the variable nozzle unit).

  In addition to the normal action of the variable nozzle unit, the facing surface of each base ring, one side surface of each variable nozzle, and the other side surface of each variable nozzle are subjected to nitriding treatment, so that the facing surface of each base ring, The surface hardness of one side surface of each variable nozzle and the other side surface of each variable nozzle can be sufficiently increased. Thereby, the sliding resistance between the facing surface of one of the base rings and one side surface of the variable nozzle, and the sliding resistance between the facing surface of the other base ring and the other side surface of the variable nozzle are reduced. This can be sufficiently reduced (the characteristic action of the variable nozzle unit).

The second of the present invention utilizes the energy of the exhaust gas from the engine, the variable capacity supercharger for supercharging air to be supplied to said engine, comprising a variable nozzle unit comprising a first invention The summary is as follows.

According to the second aspect of the present invention , the same effect as that of the first aspect of the present invention is achieved.

  According to the present invention, the sliding resistance between the facing surface of one of the base rings and one side surface of the variable nozzle can be sufficiently reduced, so that the plurality of variable nozzles are rotated in synchronization with the opening direction. Difference in turbine rotation speed (turbine rotation speed) at the same nozzle opening (openings of the plurality of variable nozzles) between the time of rotation (during opening operation) and the time of rotation in synchronization with the direction of throttling (during throttling operation) Hysteresis) can be brought close to 0, and the control performance of the variable capacity supercharger can be ensured to a high level.

FIG. 1 is a diagram showing a characteristic part of a variable nozzle unit according to an embodiment of the present invention. FIG. 2 is an enlarged view of the arrow II in FIG. FIG. 3 is a front sectional view of the variable capacity supercharger according to the embodiment of the present invention. FIG. 4 is a view taken along the line IV-IV in FIG. 2, and a turbine impeller is omitted. FIG. 5 is a view taken along the line VV in FIG. 2, and the turbine impeller is omitted. FIG. 6A is a diagram showing the relationship between the turbine rotational speed and the hysteresis with respect to the nozzle opening in the inventive product, and FIG. 6B is a diagram showing the relationship between the turbine rotational speed and the hysteresis with respect to the nozzle opening in the comparative product. FIG.

  An embodiment of the present invention will be described with reference to FIGS. In the figure, “FF” indicates the forward direction, and “FR” indicates the backward direction.

  As shown in FIG. 3, a variable displacement variable displacement supercharger 1 for a vehicle according to an embodiment of the present invention is supplied to an engine using the energy of exhaust gas from an engine (not shown). The air is supercharged (compressed). The specific configuration of the variable capacity type variable capacity supercharger 1 is as follows.

  The variable capacity supercharger 1 includes a bearing housing 3, and a plurality of radial bearings 5 and a plurality of thrust bearings 7 are provided in the bearing housing 3. Further, the plurality of bearings 5 and 7 are provided with a rotor shaft (turbine shaft) 9 extending in the front-rear direction so as to be rotatable. In other words, the rotor shaft 9 is provided in the bearing housing 3 with the plurality of bearings 5. , 7 are rotatably provided.

  A compressor 11 that compresses air using centrifugal force is disposed on the rear side of the bearing housing 3, and the specific configuration of the compressor 11 is as follows.

  A compressor housing 13 is provided on the rear side of the bearing housing 3, and a compressor impeller 15 is disposed in the compressor housing 13 (the shaft center of the compressor impeller 15, in other words, the shaft center of the rotor shaft 9). It is provided to be rotatable around. The compressor impeller 15 includes a compressor wheel 17 integrally connected to the rear end portion of the rotor shaft 9, and several compressor blades 19 provided on the outer peripheral surface of the compressor wheel 17 at intervals in the circumferential direction. It has.

  An air intake 21 for taking in air is formed on the inlet side of the compressor impeller 15 in the compressor housing 13 (the front side of the compressor housing 13), and the air intake 21 can be connected to an air cleaner (not shown). . An annular diffuser flow path 23 that pressurizes compressed air is formed on the outlet side of the compressor impeller 15 between the bearing housing 3 and the compressor housing 13, and the diffuser flow path 23 is an air intake port. 21 is communicated. Further, a compressor scroll passage 25 is formed inside the compressor housing 13, and the compressor scroll passage 25 communicates with the diffuser passage 23. An air discharge port 27 for discharging compressed air is formed at an appropriate position of the compressor housing 13, and the air discharge port 27 communicates with the compressor scroll passage 25, and is an intake manifold of the engine. (Not shown) can be connected.

  A turbine 29 that generates rotational force (rotational torque) using the pressure energy of the exhaust gas is disposed on the front side of the bearing housing 3, and the specific configuration of the turbine 29 is as follows.

  As shown in FIGS. 2 and 3, a turbine housing 31 is provided on the front side of the bearing housing 3, and the turbine housing 31 is provided on the front side of the bearing housing 3 via a fastening bolt (not shown). A first turbine housing 33 and a second turbine housing 35 provided on the front side of the first turbine housing 33 via fastening bolts (not shown) are provided. A turbine impeller 37 is provided in the turbine housing 31 so as to be rotatable around an axis (the axis of the turbine impeller 37, in other words, the axis of the rotor shaft 9). A turbine wheel 39 formed integrally with the front end portion of the shaft 9 and a plurality of turbine blades 41 provided on the outer peripheral surface of the turbine wheel 39 at intervals in the circumferential direction. As described above, the turbine impeller 37 has the same rotational speed as the rotor shaft 9 and the compressor impeller 15, and the rotational speed of the turbine impeller 37 is referred to as a turbine rotational speed.

  A gas intake 43 for taking in exhaust gas is formed at an appropriate position of the turbine housing 31 (first turbine housing 33), and the gas intake 43 can be connected to an exhaust manifold (not shown) of the engine. . Further, a turbine scroll passage 45 is formed inside the turbine housing 31 (first turbine housing 33), and the turbine scroll passage 45 communicates with the gas inlet 43. Further, a gas discharge port 47 for discharging exhaust gas is formed on the outlet side of the turbine impeller 37 (the rear side of the turbine housing 31) in the turbine housing 31 (second turbine housing 35). The turbine scroll passage 45 communicates with a catalyst (not shown).

  In the turbine housing 31, a variable nozzle unit 49 that varies the flow area (flow rate) of exhaust gas supplied to the turbine impeller 37 side is provided so as to surround the turbine impeller 37. The configuration of the variable nozzle unit 49 is as follows.

  On the rear side of the second turbine housing 35, a shroud (shroud ring) 51 that covers a turbine impeller (outer edges of the plurality of turbine blades 41) as a first base ring is provided via a fastening bolt (not shown). A plurality of first guide holes 53 are formed in the shroud 51 at equal intervals in the circumferential direction. Further, a gap adjusting plate 55 as a second base ring is integrally connected to the shroud 51 via a plurality of connecting pins 57 so as to be opposed to and separated from each other, and the gap adjusting plate 55 has a plurality of second guides. Holes 59 are formed at equal intervals in the circumferential direction.

  A plurality of variable nozzles 61 are arranged at equal intervals between the shroud 51 and the gap adjusting plate 55, and each variable nozzle 61 can rotate around an axis parallel to the axis of the turbine impeller 37. . Further, one side surface (front side surface) of each variable nozzle 61 can slide on the facing surface of the shroud 51, and the other side surface (rear side surface) of each variable nozzle 61 slides on the facing surface of the gap adjustment plate. Is possible. Further, a first nozzle shaft 63 is integrally formed on one side surface of each variable nozzle 61, and the first nozzle shaft 63 is supported by a corresponding first guide hole 53 of the shroud 51. Similarly, on the other side surface of each variable nozzle 61, a second nozzle shaft 65 is integrally formed concentrically with the first nozzle shaft 63, and the second nozzle shaft 65 corresponds to the corresponding second of the gap adjustment plate 55. It is supported by the guide hole 59.

  The variable nozzle unit 49 includes a rotation mechanism (synchronous rotation mechanism) 67 that rotates the plurality of variable nozzles 61 in synchronization with the opening direction and the narrowing direction (closing direction).

  Specifically, the shroud 51 is provided with a drive ring 69 that is rotatable about the axis of the turbine impeller 37, and the inner peripheral surface of the drive ring 69 slides on the front end side portion of the outer peripheral surface of the shroud 51. It is possible to move. In addition, a plurality of rectangular connection pieces 71 for synchronization are integrally provided in the drive ring 69 at equal intervals in the circumferential direction by caulking of the mounting pins 73, and a rectangular drive is provided at an appropriate position of the drive ring 69. The connecting piece 75 is integrally provided by caulking the mounting pin 77. A U-shaped synchronization transmission link 79 is integrally connected to the distal end portion (front end portion) of the first nozzle shaft 63 of each variable nozzle 61, and the distal end portion of each synchronization transmission link 79 is Are engaged so as to be sandwiched between the corresponding connection pieces for synchronization 71. Further, the turbine housing 31 (second turbine housing 35) is provided with a drive shaft 81 so as to be rotatable around an axis parallel to the axis of the turbine impeller 37. One end (front end) of the drive shaft 81 is provided. Are coupled to an actuator (not shown) such as a stepping motor for rotating the drive shaft 81 via a transmission lever 83 and the like. Further, a U-shaped drive transmission link 85 is integrally connected to the other end portion (rear end portion) of the drive shaft 81, and the front end portion of the drive transmission link 85 is connected to the drive connection piece 75. It is engaged so that it may be pinched | interposed into.

  Next, the characteristic part of the variable nozzle unit 49 will be described.

  A portion of the entire surface of the shroud 51 excluding the inner peripheral surface of the first guide hole 53 (most of the entire surface) is subjected to salt bath soft nitriding (tuftride treatment) as an example of nitriding treatment. In this case, the nitride layer is formed by the salt bath soft nitriding treatment. The first guide holes 53 of the shroud 51 are formed by machining the shroud 51 whose entire surface has been subjected to salt bath soft nitriding. In other words, the first guide holes 53 of the shroud 51 are provided. The salt bath soft nitriding treatment is omitted for the inner peripheral surface of the hole 53. Instead of the salt bath soft nitriding treatment being performed on the entire surface of the shroud 51, the opposed surface of the shroud 51 (the surface on which one side surface of the variable nozzle 61 slides) and the front end side portion of the outer peripheral surface (drive) The salt bath soft nitriding treatment may be performed only on the surface on which the inner peripheral surface of the ring 69 slides. In FIG. 1, the portions subjected to the salt bath soft nitriding treatment are indicated by point hatching or thick lines.

  A portion of the entire surface of the gap adjusting plate 55 excluding the inner peripheral surface of the second guide hole 59 (most of the entire surface) is subjected to salt bath soft nitriding, in other words, salt bath soft nitriding. A nitride layer is formed by the treatment. Further, each second guide hole 59 of the gap adjusting plate 55 is formed by machining the gap adjusting plate 55 whose entire surface has been subjected to the salt bath soft nitriding, in other words, the gap adjusting plate. The salt bath soft nitriding treatment is omitted for the inner peripheral surface of each of the second guide holes 59 of 55. It should be noted that the salt bath soft nitriding treatment is not applied to most of the entire surface of the gap adjusting plate 55, but only the opposite surface of the gap adjusting plate 55 (the surface on which the other side of the variable nozzle 61 slides) is softened with the salt bath. Nitriding treatment may be performed.

  The entire surface of each variable nozzle 61 (including the outer peripheral surface of the first nozzle shaft 63 and the outer peripheral surface of the second nozzle shaft 65) is subjected to salt bath soft nitriding, in other words, salt bath soft nitriding. A nitride layer is formed by the treatment. Instead of subjecting the entire surface of each variable nozzle 61 to salt bath soft nitriding, one side of each variable nozzle 61, the other side of each variable nozzle 61, and the outer periphery of the first nozzle shaft 63 of each variable nozzle 61 The salt bath soft nitriding treatment may be performed only on the surface and the outer peripheral surface of the second nozzle shaft 65 of each variable nozzle 61.

  The entire surface of the drive ring 69 is subjected to a salt bath soft nitriding treatment, in other words, a nitride layer is formed by the salt bath soft nitriding treatment. Instead of subjecting the entire surface of drive ring 69 to salt bath soft nitriding, salt bath soft nitriding may be applied only to the inner peripheral surface of drive ring 69.

  Then, the effect | action and effect of embodiment of this invention are demonstrated.

  The exhaust gas taken in from the gas inlet 43 is circulated from the inlet side of the turbine impeller 37 to the outlet side (from the upstream side to the downstream side as viewed from the flow direction of the exhaust gas) via the turbine scroll passage 45, thereby The rotor shaft 9 and the compressor impeller 15 can be rotated integrally with the turbine impeller 37 by generating a rotational force (rotational torque) using the pressure energy of the gas. Thereby, the air taken in from the air intake 21 can be compressed and discharged from the air outlet 27 via the diffuser passage 23 and the compressor scroll passage 25, and the air supplied to the engine is supercharged. can do.

  Here, when the flow rate of the exhaust gas is small (in other words, when the engine speed is in the low speed range), the drive shaft 81 and the plurality of drive transmission links 85 and the plurality of drive shafts 81 are rotated in one direction by the actuator. While the transmission link 79 for synchronization is appropriately swung, the plurality of variable nozzles 61 are rotated synchronously in the direction of squeezing. Accordingly, the flow area of the exhaust gas supplied to the turbine impeller 37 side (the throat area of the turbine impeller 37) is reduced, the flow rate of the exhaust gas is increased, and work of the turbine impeller 37 is sufficiently ensured.

  When the exhaust gas flow rate is high (in other words, when the engine speed is in the high speed range), the drive shaft 81 and the plurality of synchronizations are rotated by rotating the drive shaft 81 in the other direction by the actuator. The plurality of variable nozzles 61 are rotated in synchronism with the direction in which the variable nozzles 61 are opened while the transmission link 79 is appropriately swung. Thereby, the flow passage area of the exhaust gas supplied to the turbine impeller 37 side is increased, and a large amount of exhaust gas is supplied. (Normal operation of the variable capacity supercharger 1).

  In addition to the normal operation of the variable displacement supercharger 1, the facing surface of the shroud 51, the facing surface of the gap adjusting plate 55, one side surface of each variable nozzle 61, the other side surface of each variable nozzle 61, Since the salt bath soft nitriding treatment is applied to the outer peripheral surface of the first nozzle shaft 63 and the outer peripheral surface of the second nozzle shaft 65 of each variable nozzle 61, the surface hardness of the facing surface of the shroud 51 is sufficiently increased. be able to. Thus, sliding resistance between the facing surface of the shroud 51 and one side surface of the variable nozzle 61, sliding resistance between the facing surface of the gap adjusting plate 55 and the other side surface of the variable nozzle 61, The sliding resistance between the outer peripheral surface of the first nozzle shaft 63 and the inner peripheral surface of the first guide hole 53 of the shroud 51, and the outer peripheral surface of the second nozzle shaft 65 of each variable nozzle 61 and the first of the gap adjustment plate 55. The sliding resistance between the inner peripheral surface of the two guide holes 59 can be sufficiently reduced.

  Further, since the salt bath soft nitriding treatment is performed on the front end side portion of the outer peripheral surface of the shroud 51 and the inner peripheral surface of the drive ring 69, the front end side portion of the outer peripheral surface of the shroud 51 and the inner portion of the drive ring 69. The surface hardness of the peripheral surface can be sufficiently increased. Thereby, the sliding resistance between the front end side part of the outer peripheral surface of the shroud 51 and the inner peripheral surface of the drive ring 69 can be sufficiently reduced.

  Further, since the salt bath soft nitriding treatment is omitted for the inner peripheral surface of each first guide hole 53 of the shroud 51 and the inner peripheral surface of each second guide hole 59 of the gap adjusting plate 55, the shroud 51 is omitted. By suppressing the oxidative expansion of each first guide hole 53 and each second guide hole 59 of the gap adjusting plate 55, it is possible to sufficiently reduce the operational astringency of each variable nozzle 61 (of the variable capacity supercharger 1). Peculiar action).

  According to the embodiment of the present invention, the sliding resistance between the facing surface of the shroud 51 and one side surface of the variable nozzle 61 can be sufficiently reduced, and the operational astringency of each variable nozzle 61 can be sufficiently reduced. The same nozzle opening (the plurality of variable nozzles 61) between when the plurality of variable nozzles 61 are rotated synchronously in the opening direction (opening operation) and when the plurality of variable nozzles 61 are rotated synchronously in the throttle direction (during the throttle operation). ), The control performance of the variable capacity supercharger 1 can be ensured to a high level.

  Furthermore, in order to confirm the effect of the present invention, the inventor made a prototype of the turbine 29 according to the embodiment of the present invention as an inventive product, and applied a salt bath soft nitriding treatment to the constituent members (such as the shroud 51) of the variable nozzle unit 49. A turbine (not shown) according to a comparative example, which is different from the turbine 29 according to the embodiment of the present invention only as a comparative product, is prototyped as a comparative product, and the performance of the inventive product and the comparative product is simulated by simulating actual operating conditions. The test was conducted and the results were summarized as shown in FIGS. 6 (a) and 6 (b). That is, the hysteresis of the turbine rotational speed at the same nozzle opening occurs for the comparative product, whereas the hysteresis of the turbine rotational speed at the same nozzle opening becomes almost zero for the comparative product. The effect was confirmed.

  In addition, this invention is not restricted to description of the above-mentioned embodiment, For example, it can implement in a various aspect as follows. That is, not only the variable nozzle unit 49 having the both end support type variable nozzle 61 having the first nozzle shaft 63 and the second nozzle shaft 65, but also any of the first nozzle shaft 63 and the second nozzle shaft 65. The present invention may be applied to a variable nozzle unit having a cantilevered variable nozzle having such a nozzle shaft. Further, the salt bath soft nitriding treatment used in the configuration of the variable nozzle unit 49 may be changed to another nitriding treatment such as a gas nitriding treatment. Further, the scope of rights encompassed by the present invention is not limited to these embodiments.

DESCRIPTION OF SYMBOLS 1 Variable displacement supercharger 3 Bearing housing 9 Rotor shaft 11 Compressor 13 Compressor housing 15 Compressor impeller 29 Turbine 31 Turbine housing 33 First turbine housing 35 Second turbine housing 37 Turbine impeller 49 Variable nozzle unit 51 Shroud 53 First guide hole 55 Gap adjustment plate 57 Connecting pin 59 Second guide hole 61 Variable nozzle 63 First nozzle shaft 65 Second nozzle shaft 67 Rotating mechanism 69 Drive ring 71 Synchronizing connecting piece 73 Mounting pin 75 Driving connecting piece 77 Mounting pin 79 Synchronizing Transmission link 81 Drive shaft 83 Transmission lever 85 Drive transmission link

Claims (7)

In the variable nozzle unit that varies the flow area of the exhaust gas supplied to the turbine impeller side in the variable capacity supercharger,
A pair of base rings that are integrally connected in a state of being opposed to each other, and at least one of which has a plurality of guide holes formed at equal intervals in the circumferential direction;
A pair of the base rings are arranged at equal intervals in the circumferential direction, are rotatable about an axis parallel to the axis of the turbine impeller, and one side surface slides on the opposite surface of the one base ring. The nozzle shaft is movable and the other side surface is slidable on the opposite surface of the other base ring, is integrally formed on at least one side surface, and is rotatably supported in the corresponding guide hole. A plurality of variable nozzles;
A rotation mechanism that rotates the variable nozzles in synchronization with a direction in which the variable nozzles are opened and squeezed; and
A variable nozzle unit in which the facing surface of each base ring, one side surface of each variable nozzle, and the other side surface of each variable nozzle are subjected to nitriding treatment, but the inner peripheral surface of each guide hole is not subjected to nitriding treatment . Nitriding the outer peripheral surface of the nozzle axes of the variable nozzle is performed, the variable nozzle unit according to claim 1. The synchronous rotation mechanism is
A drive ring that is rotatably provided on any of the base rings and whose inner peripheral surface is slidable on the outer peripheral surface of any of the base rings;
A plurality of connection pieces provided at equal intervals on the drive ring;
A transmission link integrally connected to the nozzle shaft of each variable nozzle and having a tip engaged with the corresponding connecting piece;
Equipped with an actuator for rotating the drive ring,
Any of the nitriding treatment to the outer peripheral surface and inner peripheral surface of the drive ring of the base ring is applied, a variable nozzle unit according to claim 1 or claim 2. The plurality of guide holes are respectively formed a plurality of the guide holes at equal intervals in the circumferential direction on the pair of the base ring, wherein the nozzle axis is formed integrally on both sides of each variable nozzle, claim variable nozzle unit according to any of one of claims 3 to 1. In the variable capacity supercharger that uses the energy of exhaust gas from the engine to supercharge the air supplied to the engine,
It is provided with a variable nozzle unit according to any one of claims 1 to 4, a variable capacity turbocharger. A pair of base rings in which a plurality of guide holes are formed in at least one of the circumferential directions;
A variable nozzle having a nozzle shaft disposed between the pair of base rings and rotatably supported in the guide hole;
A variable nozzle unit including a rotation mechanism for rotating the variable nozzle,
A variable nozzle unit in which the opposing surfaces of the pair of base rings, one side surface of the variable nozzle, and the other side surface of the variable nozzle are subjected to nitriding treatment, while the inner peripheral surface of the guide hole is not subjected to nitriding treatment . A first nozzle ring formed with a first guide hole;
A second nozzle ring formed with a second guide hole and facing the first nozzle ring;
A variable nozzle disposed between the first nozzle ring and the second nozzle ring and slidable relative to the first nozzle ring and the second nozzle ring;
A nozzle shaft formed on the variable nozzle and supported by the first guide hole and the second guide hole;
Nitride layers are formed on the surfaces of the variable nozzle and the first nozzle ring that slide with each other and the surfaces of the variable nozzle and the second nozzle ring that slide with each other. The variable nozzle unit, wherein a nitride layer is not formed on the inner peripheral surface and the inner peripheral surface of the second guide hole.

Images