Variable displacement exhaust turbocharger equipped with variable nozzle mechanism

A variable displacement exhaust turbocharger is provided with a plurality of nozzle vanes that are rotatably supported by a nozzle mount, a drive ring that is interlocked with an actuator and fits to a guide part of the nozzle mount, a lever plate having one end coupled to the drive ring and the other end coupled to the nozzle vane, and a variable nozzle mechanism that varies the vane angle of the nozzle vane by rotating the drive ring. A bulge suppressing portion is provided for absorbing bulging occurring on an outer peripheral surface of the guide part, the bulging being caused by the press-fitting of a nail pin into a press-fitting hole in a direction slightly toward the rotational axis with respect to the guide section and following the axial direction of the nozzle mount.

TECHNICAL FIELD

The present invention relates to a structure for retaining a drive ring rotatable with respect to a nozzle mount in a variable displacement exhaust turbocharger, which is used for an exhaust turbocharger of an internal combustion engine and which is equipped with a variable nozzle mechanism for varying a vane angle of a plurality of nozzle vanes.

BACKGROUND ART

As one variable displacement exhaust turbocharger which is used for an exhaust turbocharger of an internal combustion engine and which is equipped with a variable nozzle mechanism for varying a vane angle of a plurality of nozzle vanes, the technique of JP 2011-43119 is provided.

This technique is illustrated inFIG. 9A,FIG. 9BandFIG. 9Cof the attached drawings.FIG. 9Ais a plan view of a configuration of a nozzle vane08before being connected to a first link member074.FIG. 9Bis a Z arrow view ofFIG. 9A.FIG. 9Cis an enlarged view of a second shaft end portion ofFIG. 9A.

On an opposite side of a fitting part081from a vane064, a protruding portion085is provided. The protruding portion085is inserted in a hole074aof a first link member074and then pressed in a direction of a center axis S to form a caulking portion.

Then, in a notch area of a notch082in a second bearing066, a press-fitting portion086and a non press-fitting portion087are provided. The length of the press-fitting portion086in the direction perpendicular to the notch082is set slightly larger than the length of the hole074ain this above perpendicular direction.

Meanwhile, the length of the press-fitting portion086in a direction parallel to the notch082and perpendicular to the center axis S is set slightly smaller or equal to the length of the hole074in this perpendicular direction.

Therefore, the notch082has the shape that decreases from the press-fitting portion086toward the non-press-fitting portion087and the protruding portion085from the press-fit portion086as it goes to the tip.

As the notch082has a shape that decreases as it goes to the tip, it is easy to fit the fitting part081into the hole074aof the first link member074. Thus, when press-fitting the press-fitting portion086to the hole074a,even if a press-fit margin between the press-fitting portion086and the hole074is set large, the press-fitting force required for press-fitting does not increase excessively and occurrence of the press defects is suppressed.

CITATION LIST

Patent Literature

SUMMARY

Technical Problem

However, the technique of Patent Literature 1 (JP 2011-43119A) is to eliminate a relative movement between the second bearing066and the first link member074by inserting the notch082into the hole074aeasily by a clearance formed between the non press-fitting portion082of the notch082of the second bearing066and the hole074of the first link member074and then caulking the protruding portion085in the axial direction of the second bearing066to press the notch082against a wall of the hole074a.

Therefore, there is no technical disclosure as to how to suppress bulging of the first link member074caused by the press-fitting portion086inserted in the hole074aof the first link member074.

The present invention has been made to solve the above problems, and it is an object of the present invention to improve durable reliability of a variable displacement exhaust turbocharger equipped with a variable nozzle mechanism, by providing a bulge suppressing portion for suppressing a bulging portion generated at an outer peripheral part of a guide part of a nozzle mount when a press-fitting pin is press-fitted into a press-fitting hole formed in the nozzle mount along the axial direction, thereby preventing fixation of an inner peripheral surface of a drive ring and an outer peripheral surface of the guide part.

Solution to Problem

To solve the above issues, the present invention provides a variable displacement exhaust turbocharger which is equipped with a variable nozzle mechanism and is driven by exhaust gas from an engine, the variable displacement exhaust turbocharger comprising:

a plurality of nozzle vanes supported rotatably by a nozzle mount which is fixed to a case including a turbine casing of the variable displacement exhaust turbocharger;

a drive ring which is interlocked with an actuator and is fitted to an annular guide part protruding from a center part of the nozzle mount in an axial direction;

a plurality of lever plates each of which is fitted to a groove formed in the drive ring at one end via a connection pin and is connected to the nozzle vane at the other end;

the variable nozzle mechanism configured to swing the plurality of lever plates by rotation of the drive ring so as to change a vane angle of the plurality of nozzle vanes; and

a press-fitting pin which is press-fit to a side of the nozzle mount at a position slightly closer to a rotation axis than the annular guide part,

wherein a bulge suppressing portion is provided in at least one of the press-fitting pin or a press-fitting hole formed in the axial direction of the nozzle mount so as to absorb and suppress a bulge of an outer peripheral surface of the annular guide part generated when the press-fitting pin is press-fit in the press-fitting hole.

With the above configuration, by providing the bulge suppressing portion which is configured to suppress bulging of the press-fitting hole of the guide part of the nozzle part out of the outer peripheral surface in the radial direction when press-fitting the pin into the press-fitting hole, it is possible to prevent fixation of the inner peripheral surface of the drive ring and the outer peripheral surface of the guide part.

It is preferable in the present invention that a depth of the press-fitting hole is greater than a thickness of the annular guide part in the axial direction, and the bulge suppressing portion includes an enlarged diameter part which is formed in the press-fitting hole in such a manner that a hole diameter of the press-fitting hole is larger than an outer diameter of the press-fitting pin at least in a range corresponding to the thickness of the annular guide part in the axial direction from an insertion side.

With this configuration, as the bulge suppression portion is formed such that the hole diameter of the press-fitting hole is larger than the outer diameter of the press-fitting pin in a range approximately equivalent to the thickness of the drive ring from the pin insertion side, the bulge suppressing portion is capable of suppressing bulge of the outer peripheral surface of the guide part due to the press-fitting of the pin and also prevent fixation of the inner peripheral surface of the drive ring and the outer peripheral surface of the guide part.

It is also preferable in the present invention that a depth of the press-fitting hole is greater than a thickness of the annular guide part in the axial direction, and the bulge suppressing portion includes a reduced diameter part which is formed in the press-fitting pin in such a manner that an outer peripheral part of the press-fitting pin is smaller than a diameter of the press-fitting hole at least in a range corresponding to the thickness of the annular guide part in the axial direction from a base part toward a tip part of the press-fitting pin.

With this configuration, as the bulge suppressing portion is formed such that the outer diameter of the press-fitting pin is smaller than the hole diameter of the press-fitting hole in a range approximately equivalent to the thickness of the drive ring from the pin insertion side, the bulge suppressing portion is capable of suppressing bulge of the outer peripheral surface of the guide part due to the press-fitting of the pin and also prevent fixation of the inner peripheral surface of the drive ring and the outer peripheral surface of the guide part.

Moreover, the press-fitting pin can be precisely formed by lathe machining, whereby cost reduction can be achieved.

It is also preferable in the present invention that the bulge suppressing portion includes a notch which is formed along an axial direction of the press-fitting pin in such a manner that the notch is on a side nearer to the outer peripheral surface of the annular guide part.

With this configuration, the press-fitting area can be longer and thus, perpendicularity of the press-fitting pin with respect to the nozzle mount is stabilized.

It is also preferable in the present invention that the bulge suppressing portion comprises a cylindrical spring pin which has a C-shaped cross-section and is press-fitted into the press-fitting hole, and a pin which is press-fitted into an inner cylindrical part of the cylindrical spring pin.

With this configuration, as the C-shaped notch portion of the cylindrical spring pin absorbs the bulge caused by press-fitting of the pin, it is possible to prevent bulging on the outer peripheral surface of the guide part and also prevent fixation of the inner peripheral surface of the drive ring and the outer peripheral surface of the guide part.

Therefore, it is no longer necessary to regulate orientation when press-fitting the nail pin20. This facilitates the press-fitting work.

It is also preferable in the present invention that the bulge suppressing portion is a cutout portion of the outer peripheral surface of the guide part which is cut out in advance in an amount equivalent to a bulge amount.

With this configuration, the bulge suppressing portion is formed by predicting a bulge amount of the bulging portion caused by press-fitting the pin, and cutting out a portion in the bulge amount. The cutout portion is restored by a bulge caused by press-fitting of the pin, and the cutout portion is restored to a smooth peripheral surface. As a result, it is possible to prevent fixation of the inner peripheral surface of the drive ring and the outer peripheral surface of the guide part.

Moreover, as it is no longer necessary to regulate orientation of the pin, the press-fitting work is facilitated. Further, as the pin is press-fitted over the entire circumference of the pin, it is to improve fixing of the pin with respect to the nozzle mount.

It is also preferable in the present invention that the press-fitting pin is a headed pin with a flange-shaped head for retaining an inner peripheral part of the drive ring so that inner peripheral part of the drive ring does not come off from the guide part.

With this configuration, the drive ring is retained by the flange-shaped head of the press-fitting pin so as to prevent the drive ring from falling out from the guide part. This simplifies the structure, whereby cost reduction can be achieved and the drive ring can be retained reliably.

It is also preferable in the present invention that the press-fitting pin is a stopper pin which is configured to restrict an opening degree of the nozzle vane by contacting a side face of the lever plate.

With this configuration, as the press-fitting pin is a stopper pin which is configured to restrict an opening degree of the nozzle vane by contacting a side face of the lever plate, the structure is simplified by making the edge of the outer peripheral part of the guide part into a smooth outer peripheral surface, and the performance of the variable nozzle mechanism is improved by accurately regulating the swing range of the lever plate.

It is preferable in the present invention that the press-fitting pin is a lock pin for positioning between the bearing housing and the nozzle mount.

With this configuration, as the press-fitting pin is a lock pin for positioning between the bearing housing and the nozzle mount, the structure is simplified and the performance of the variable nozzle mechanism is improved by making the edge of the outer peripheral part of the guide part into a smooth outer peripheral surface.

Advantageous Effects

By providing the bulge suppressing portion which is configured to suppress bulging of the press-fitting hole of the guide part of the nozzle part out of the outer peripheral surface in the radial direction when press-fitting the pin into the press-fitting hole, it is possible to prevent fixation of the inner peripheral surface of the drive ring and the outer peripheral surface of the guide part.

Moreover, as the bulge suppressing portion is formed such that outer peripheral part of the nail pin is smaller than the hole diameter of the press-fitting hole, the pin can be precisely formed by lathe machining, whereby cost reduction can be achieved.

Further, by adopting the stopper pin for restricting swinging of the lever plate which is configured to operate opening of the nozzle vane, it is possible to achieve improved easiness of press-fitting work and reduced cost.

DETAILED DESCRIPTION

It is intended, however, that unless particularly specified, dimensions, materials, shapes, relative positions and the like of components described in the embodiments shall be interpreted as illustrative only and not limitative of the scope of the present invention.

FIG. 1is a longitudinal cross-sectional view of a main part of a variable displacement exhaust turbocharger equipped with a variable nozzle mechanism according to an embodiment of the present invention.

FIG. 1illustrates a turbine casing30, a scroll38of a scroll shape formed in an outer peripheral part of the turbine casing30, a turbine rotor of a radial flow type34, a compressor35, a turbine shaft32for connecting the turbine rotor34and the compressor35, a compressor housing31and a bearing housing36.

The turbine shaft32connecting the turbine rotor34and the compressor35is rotatably supported by the bearing housing36via two bearings37,37. The drawing also illustrates an exhaust gas outlet8and a rotation axis CL of the exhaust turbocharger.

A plurality of nozzle vanes2is arranged on an inner circumferential side of the scroll38at equal intervals in the circumferential direction of a turbine and is supported rotatably by a nozzle mount5. A nozzle shaft2ais formed on a vane end of the nozzle vane2and is rotatably supported by the nozzle mount5which is fixed to the turbine casing30.

On an opposite side of the nozzle shaft2afrom the vane end, the nozzle shaft2ais connected to a drive ring3via a lever plate1. The drive ring3is configured to change a vane angle of the nozzle vane2by rotation of the nozzle shaft2a.

An actuator rod33is configured to transmit a reciprocating motion from an actuator (not shown). A drive mechanism39is configured to convert the reciprocating motion of the actuator rod33into a rotational motion via a link15which is fixed to a rotation shaft15a,and engage a drive pin15adisposed at one end of a lever15bwhose other end is fixed to the rotation shaft15awith an engagement groove3z(seeFIG. 2) formed in an outer peripheral part of the drive ring3so as to rotate the drive ring3.

The section surrounded by a dotted line is a variable nozzle mechanism100for varying a vane angle of the nozzle vane2.

In the operation of the variable displacement exhaust turbocharger equipped with the variable nozzle mechanism which is configured as illustrated inFIG. 1, exhaust gas from an internal combustion engine (not shown) enters the scroll38and flows into the nozzle vanes2while swirling along the scroll shape of the scroll38. After flowing past between the nozzle vanes (an opening area), the exhaust gas flows in the turbine rotor34from its outer peripheral side. Then, the exhaust gas flows radially toward the center to perform expansion work in the turbine rotor34. After performing the expansion work, the exhaust gas flows out in the axial direction and then guided toward the exhaust gas outlet8and sent outside of the turbine rotor34.

In order to control the displacement of this variable displacement turbine, a vane angle of the nozzle vanes2at which a flow rate of the exhaust gas through the nozzle vanes2abecomes a desired flow rate is set by a vane angle controller (not shown) with respect to the actuator. The reciprocal displacement of the actuator with respect to this vane angle is transmitted to the drive ring3via the drive mechanism39so as to drive and rotate the drive ring3.

By rotation of the drive ring3, the lever plate1is caused to rotate around the nozzle shaft2avia a connection pin10which is described later. By rotation of the nozzle shaft2a,the nozzle vane2is rotated to the vane angle which is set as to the actuator. As a result, the area between adjacent vanes (the opening area between adjacent vanes) changes.

FIG. 2Ais a front view of the variable nozzle mechanism, which is taken from the lever plate1side.FIG. 2Bis a cross-sectional view in A-A ofFIG. 2A. The drawings illustrate a variable nozzle mechanism100for varying the vane angle of the nozzle vanes2. The variable nozzle mechanism100is configured as described below.

The drive ring3formed in a disk shape is externally fitted to a guide part5aof a cylinder shape (a ring shape) which protrudes in the direction of the axis CL of the nozzle mount5(in the same direction as the rotation axis of the exhaust turbocharger) to be rotatably supported. Further, grooves3y,with which the connection pins10engage, are formed at an outer circumferential side at equal intervals in the circumferential direction. The grooves3yare described later. The drive mechanism39has a drive groove3zwhere the actuator rod33engages.

The same number of the lever plates1as the grooves3yof the drive ring3is provided at equal intervals in the circumferential direction.

Each of the lever plates1is fitted in the groove3yof the drive ring3via the connection pin10on an outer circumferential side (one end) and is connected to the nozzle shaft2afixed to the nozzle vane2on an inner circumferential side (the other end).

Further, the nozzle shaft2ais supported about its axis to be rotatable with respect to the nozzle mount5.

A nozzle plate6of an annular shape is connected to the nozzle mount5by a plurality of nozzle supports61.

A stopper pin7protrudes from a center part of the nozzle mount5in the direction of the axis CL, and a plurality of stopper pins7is arranged circumferentially at equal intervals in an outer peripheral part of an end surface of the guide part5aof a cylindrical shape (a ring shape). Further, the plurality of stopper pins7(four stopper pins in this embodiment) is press-fitted in a plurality of press-fitting holes (not shown) along the direction of the axis CL.

The stopper pin7is a so-called opening restricting member for restricting swinging of the lever plate1at a closed position of the nozzle vanes (a closed position of the opening area), the lever plate1being configured to swing about the nozzle shaft2ain response to rotating movement of the driving ring3.

A lock pin9is a positioning pin for improving assembling accuracy of the bearing housing36and the nozzle mount5. By restricting an assembling angle of the bearing housing36and the nozzle mount5(assembling accuracy), a driving amount of the drive ring3is accurately transmitted with respect to a driving amount of the actuator, and the opening degree of the nozzle vane2can be precisely controlled, thereby fully exerting the performance of the turbocharger.

In the variable nozzle mechanism, as illustrated inFIG. 2B, the lever plate1is arranged on an outer side in the axial direction (on the exhaust gas outlet8side inFIG. 1), and between a side face of the lever plate1and a side face of the nozzle mount5, the drive ring3is arranged in the state where the drive ring3, the lever plate1and the nozzle mount5are arranged next to one another in the axial direction.

The connection pin10is formed integrally with a base material by pressurizing one side face of each of the lever plates1by a press machine so that a rectangular depression10ais formed on the side face and a rectangular protrusion is formed on the other side face by extrusion.

The drive ring3of the variable nozzle mechanism100having such configuration needs to be retained with respective appropriate clearances between the nozzle mount5and the lever plate1and between the inner peripheral surface of the drive ring3and the outer peripheral surface of the guide part51.

If the clearance is greater than a specified value, the drive ring3rocks in the axial direction of the nozzle mount5. This can result in one-side hitting of a thrust-direction end of a sliding face of the drive ring3against the guide part (one-side contact), which causes fixation.

On the other hand, if the clearance is smaller than the specified value, the sliding resistance of the nozzle mount5increases, which causes fixation of the sliding portion.

To prevent the fixation, it is desired to ensure an appropriate amount of clearance in the thrust direction of the nozzle mount5and the drive ring. To maintain the appropriate amount of clearance, a nail pin which is a press-fitting pin with a flange extending in the radial direction is press-fitted in the outer peripheral part of the end face of the guide part5ain the thrust direction so as to secure an appropriate clearance by means of the flange of the press-fitting pin.

FIG. 3Ais an enlarged cross-sectional view of a part where a nail pin serving as the press-fitting pin is press-fitted in the nozzle mount5according to a first embodiment of the present invention, which is taken in B-B ofFIG. 2A.FIG. 3Bis an enlarged view of a press-fitting hole on the nozzle mount.FIG. 3Cis a schematic view of the nail pin to be press-inserted in the press-fitting hole ofFIG. 3B.

InFIG. 3A, the drive ring3of a disk shape is externally fitted with a small clearance to the guide part5aof a cylinder shape (a ring shape) which protrudes in the axial direction of the nozzle mount5.

A nail pin20has a flange portion20ato prevent rocking of the drive ring3in the direction of the axis CL of the nozzle mount5during rotation of the drive ring3. This nail pin20is press-fitted in a press-fitting hole5b.

Therefore, the press-fitting position of the nail pin20is disposed slightly closer to the center axis CL of the nozzle mount5from an outer peripheral line of the end face of the cylindrical guide part5a,and a plurality of the press-fitting positions is arranged at equal intervals in the circumferential direction.

FIG. 3Bis a detailed view of the press-fitting hole5b.FIG. 3Cis an illustration of the nail pin20to be press-fitted in the press-fitting hole5b.

The press-fitting hole5bis formed in the outer peripheral part of the end face of the guide part5aalong the axis CL of the nozzle mount5, and a plurality of the press-fitting holes5bis arranged at equal intervals in the circumferential direction.

The press-fitting hole5bchanges in hole diameter at two stages along an axis of the hole. Specifically, the hole diameter of the press-fitting hole5bis ø1on an opening side where the nail pin20is inserted and changes to ø2on its deeper side. The length L1of the section with the hole diameter ø1is slightly larger than the width T of the sliding face of the drive ring3(thickness in the axial direction) by length L3. In other words, the width T of the sliding face of the drive ring3is maintained within the range of L1.

The hole diameter ø2is smaller than a diameter ø3of a tip part of the nail pin20, and the hole diameter ø2and the diameter ø3are formed according to a dimensional relationship of press-fitting. The length L2of the tip part of the pin20(press-fit margin) which is inserted in the hole diameter ø2is set so that the nail pin20does not come out from the press-fitting hole5beasily during the operation of the drive ring3.

As illustrated inFIG. 3C, the nail pin20, however, has a constant pin diameter ø3from the tip to the flange portion20a.

A protruding portion20cis a portion where a press-fitting tool is abutted when press-fitting the nail pin20into the press-fitting hole5b.Without the protruding portion20c,a pin portion20bdeforms during insertion of the nail pin20due to the press-fitting pressure acting on the pin portion20b.The deformation of the pin portion20baccompanies deformation of the flange portion20a.Therefore, the protruding portion20cis provided to prevent deformation of the nail pin20and facilitate assembling thereof.

Further, a height L7of the guide part5ais set so that an appropriate clearance L4is secured between the flange portion20aof the nail pin20and the drive ring3when the nail pin20is press-fitted into the press-fitting hole5b.

Furthermore, as the space5eserving as a bulge suppressing portion is formed in L1section of the nail pin20and the press-fitting hole5b,although a section of the press-fitting hole5bof the nozzle mount5on the drive ring3side is thin and has low rigidity, it, is possible to prevent, outward bulging of the section where the sliding face width (T) of the drive ring3is located.

A relief R is provided in a section of connection between a protruding portion52on a side face of the nozzle mount5(a contact face with the drive ring3) and the guide part5aso that the edge of the sliding face with width T of the drive ring reliably contacts the guide part5a.

By ensuring that the drive ring3contacts the guide part5ain the entire range of the sliding face of the drive ring3, it is possible to reduce rocking of the drive ring3in the thrust direction during rotation of the drive ring3, thereby preventing the fixation of the edge of the sliding face width of the drive ring and the guide part5a.

Further, the protruding portion52is formed in a disk shape on an outer circumferential side of the relief R of the side face and constitutes a contact face where the radial-direction side face of the drive ring3contacts. The protruding portion52is provided to reduce frictional resistance between the side face of the nozzle mount and the radial-direction side face of the drive ring3, thereby enhancing smooth rotation of the drive ring3.

With the above configuration, as the space5eserving as a bulge suppressing portion is formed in L1section of the nail pin20and the press-fitting hole5b,press-fitting of the nail pin20does not generate a bulging portion on the surface of the guide part5ain the section where the sliding face width (T) of the drive ring3is located. Therefore, it is possible to maintain the surface of the guide part5asmooth and prevent the fixation of the drive ring3and the guide part5a.

Moreover, as the diameter of the press-fitting hole5bin the section L1is large, press-fitting work is facilitated.

A second embodiment will be described in reference toFIG. 4.

The structure is the same as the first embodiment, except for press-fitting of a lock pin serving as the press-fitting pin for positioning between the nozzle mount and the bearing housing on the outer peripheral part of the nozzle mount5. Thus, structures such as the variable nozzle mechanism will not be described further herein.

In addition, for parts of the same shape with the same effect, are assigned the same reference numerals, and a description thereof will be omitted.

FIG. 4is a partial enlarged view of a C-C section ofFIG. 2Awhere a lock pin is press-fitted in the nozzle mount5according to a second embodiment of the present invention.

Although the bearing housing36is not shown inFIG. 2A, the bearing housing36is illustrated inFIG. 4to clarify the disposition of the lock pin9.

FIG.4shows the nozzle mount5and the drive ring3. The drive ring3is externally fitted to the guide part5aof the nozzle mount5.

In the vicinity of the outer peripheral part of the guide part5aof the nozzle mount5, a plurality of press-fitting holes5his formed along the axis CL of the nozzle mount5. In the plurality of press-fitting holes5h,a plurality of lock pins9is press-fitted. The lock pins9serve as the press-fitting pins for positioning between the nozzle mount5and the bearing housing36.

The press-fitting hole5hhas a hole diameter allowing the space5eto be formed in an amount of the tip part of the guide part5a(in section corresponding to L1ofFIG. 3B), the space5eserving as a bulge suppressing portion for preventing bulging of the outer peripheral part of the guide part5aduring press-fitting of the lock pin9.

Further, the section on a deeper side of the press-fitting hole from the space5e(in a section corresponding to L2ofFIG. 3B) is where the lock pin9is press-fitted.

An opposite end of the lock pin9from the press-fitting portion being press-fitted is fitted to the bearing housing36, thereby positioning the nozzle mount5with precision.

With this configuration, as the space5eserving as a bulge suppressing portion is formed in a L1corresponding section of the press-fitting hole5hand the lock pin9, press-fitting of the lock pin9does not generate a bulging portion on the surface of the guide part5a.Therefore, it is possible to maintain the surface of the guide part5asmooth and prevent the fixation of the drive ring3and the guide part5a.

Moreover, as the diameter of the press-fitting hole5bin the section L1is large, press-fitting work is facilitated.

Further, since the assembling accuracy of the bearing housing36and the nozzle mount5is improved, a driving amount of the drive ring3is transmitted accurately relative to a driving amount of the actuator, and the opening of the nozzle vane2can be precisely controlled, thereby exerting sufficient performance of the turbocharger.

Furthermore, the stopper pin7for restricting the opening degree of the nozzle vane2have configuration similar to the aforementioned lock pin9and thus will not be described further.

A third embodiment will be described in reference toFIG. 5A,FIG. 5BandFIG. 5C.

The structure is the same as the first embodiment, except for press-fitting of a nail pin21in the nozzle mount51. Thus, structures such as the variable nozzle mechanism will not be described further herein.

In addition, for parts of the same shape with the same effect, are assigned the same reference numerals, and a description thereof will be omitted.

FIG. 5Ais an enlarged cross-sectional view of a section where a nail pin according to the third embodiment of the present invention is press-fitted in the nozzle mount.FIG. 5Bis an enlarged view of a press-fitting hole on the nozzle mount side.FIG. 5Cis a schematic view of the nail pin to be inserted in the press-fitting hole ofFIG. 5B.

FIG. 5Ashows a nozzle mount51and a lever plate1. InFIG. 5A, the drive ring3is externally fitted to a guide part51aof the nozzle mount51.

The press-fitting hole51bhas a diameter ø2and is formed in the outer peripheral part of the end face of the guide part51aalong the axis CL of the nozzle mount51, and a plurality of the press-fitting holes51bis arranged in the peripheral part at equal intervals in the circumferential direction.

The nail pin21is a press-fitting pin to be press-fitted in the press-fitting hole51b.The nail pin21is formed in a diameter ø3at a tip part21band in a diameter ø4at a reduced diameter part21cbetween the diameter ø3and a flange portion21a,and diameter ø3>diameter ø4.

The length L1of the diameter ø4section of the reduced diameter part21cis determined to secure a clearance L4between the side face of the drive ring3and the flange portion21a(appropriate clearance L1=t+L4).

The length L5of the diameter ø3of the tip part21b(press-fit margin) is set so that the nail pin21does not come out from the press-fitting hole51beasily during the operation of the drive ring3when inserting the nail pin21into the press-fitting hole51b.

Further, each of the tip part21bof the nail pin21and the press-fitting hole51bis formed in interference-fitting dimension of a respective elastic deformation region so that the section (L1) of the press-fitting hole51bopposing the drive ring does not plastically deform when press-fitting the nail pin21into the press-fitting hole51b.

With this configuration, as the bulge suppressing portion21eis formed in the L1section of the press fitting hole51band the nail pin21, press-fitting of nail pin21does not generate a bulging portion on the surface of the guide part51ain the section where the sliding face width (T) of the drive ring3is located. Therefore, it is possible to maintain the surface of the guide part51asmooth and prevent the fixation of the drive ring3and the guide part51a.

Moreover, the nail pin21can be formed to have a stepped portion, etc. by lathe machining, whereby cost reduction can be achieved.

This embodiment is also applicable to the case where a pin-shape member other than the nail pin, such as the lock pin and the stopper pin for restricting the opening of the nozzle vane, is press-fitted in the nozzle mount.

A fourth embodiment will be described in reference toFIG. 6A,FIG. 6B,FIG. 6CandFIG. 6D.

The structure is the same as the second embodiment, except for a shape of the nail pin. Thus, structures except for the nail pin will not be described further herein.

In addition, for parts of the same shape with the same effect, are assigned the same reference numerals, and a description thereof will be omitted.

FIG. 6Ais a schematic view of a nozzle mount and a nail pin according to a fourth embodiment of the present invention, illustrating a direction of a notch formed on the nail pin with respect to the nozzle mount.FIG. 6Bis a schematic view of the nail pin having the notch.FIG. 6Cis a view on Y arrow ofFIG. 6B.FIG. 6Dis a schematic view of the state where the nail pin is press-fitted in the press-fitting hole.

A nail pin22of this embodiment includes a notch22cof a belt shape which is formed in a pin portion22balong an axial direction of the pin portion22bas illustrated inFIG. 6BandFIG. 6C.

The press-fitting hole5bis formed in the outer peripheral part of the end face of the guide part51aalong the axis CL of the nozzle mount51, and a plurality of the press-fitting holes5bis arranged in the peripheral part at equal intervals in the circumferential direction.

As illustrated inFIG. 6A, when press-fitting the nail pin22into the press-fitting hole51b,the nail pin22is press-fitted with the notch22facing the drive ring3side.

FIG. 6Dillustrates the state where the nail pin22is press-fitted in the press-fitting hole51b.In the drawing, a bulge suppressing portion22eis formed on the drive ring3side.

With the above configuration, as the bulge suppressing portion is formed by the notch22c,press-fitting of the nail pin20does not generate a bulging portion on the surface of the guide part51ain the section where the sliding face width (T) of the drive ring3is located. Therefore, it is possible to maintain the surface of the guide part51asmooth and prevent the fixation of the drive ring3and the guide part51a.

Moreover, the press-fitting area becomes longer across the pin portion22band thus, perpendicularity of the nail pin with respect to the nozzle mount is stabilized.

This embodiment is also applicable to the case where a pin-shape member other than the nail pin, such as the lock pin and the stopper pin for restricting the opening of the nozzle vane, is press-fitted in the nozzle mount.

A fifth embodiment will be described in reference toFIG. 7A,FIG. 7B,FIG. 7CandFIG. 7D.

The structure is the same as the second embodiment, except for the configuration for press-fitting the nail pin21into the press-fitting hole of the nozzle mount via a cylindrical spring pin. Thus, structures such as the variable nozzle mechanism will not be described further herein.

In addition, for parts of the same shape with the same effect, are assigned the same reference numerals, and a description thereof will be omitted.

FIG. 7Ais an oblique view of a cylindrical spring pin according to the fifth embodiment of the present invention.FIG. 7Bis a schematic oblique of a nail pin to be press-fitted in the cylindrical spring ofFIG. 7A.FIG. 7Cis a schematic view of the state where the nail pin is press-fitted in the press-fitting hole via the cylindrical spring pin.FIG. 7Dis a view of F-F arrow ofFIG. 7C.

In FIG.7A, a cylindrical spring pin24has a notch24aformed by cutting out a portion of a cylindrical shape thereof along an axis of the cylindrical shape. The cylindrical spring pin24has a substantially C-shaped cross-section in a direction perpendicular to an axis of the cylindrical shape.

InFIG. 7B, a nail pin23comprises a pin portion23bwhich is press-fitted in the press-fitting hole51b,a flange portion23afor restricting rocking of the drive ring3, and a protrusion23cserving as a receiving part for a press-fitting tool during the press-fitting.

FIG. 7Cillustrates the state where the nail pin23is press-fitted in the press-fitting hole51bvia the cylindrical spring pin24.

The press-fitting hole51bis formed in the outer peripheral part of the end face of the guide part51aalong the axis CL of the nozzle mount51, and a plurality of the press-fitting holes51bis arranged in the peripheral part at equal intervals in the circumferential direction.

The cylindrical spring pin24is press-fitted press-fitting hole51bin such a state that an outer diameter of the cylindrical spring pin24is in an interference-fitting state with respect to a diameter ø2of the press-fitting hole51b.

The nail pin23as the press-fitting pin is press-fitted in an inner cylindrical part24bof the cylindrical spring pin24in an interference-fitting state.

Further, each of the length L7of the pin portion23bof the nail pin23and the length L8of the cylindrical spring pin24is preferably greater than the width T of the sliding face of the drive ring3.

The pressure acting on the outer peripheral part of the guide part51ais uniformized in the thrust direction by press-fitting the cylindrical spring pin24and the nail pin23so that the clearance between the outer peripheral surface of the guide part51aand the inner peripheral surface of the drive ring3does not change in the thrust direction.

FIG. 7Dis a view of F-F arrow ofFIG. 7C, and the cylindrical spring pin24is press-fitted in the press-fitting hole51bin the state where the notch24aof the cylindrical spring pin24is disposed in the circumferential direction of the guide part51ain this embodiment.

The cylindrical spring pin24deforms when the nail pin23is press-fitted in the inner cylindrical part24bof the cylindrical spring pin24, and this deformation can be absorbed by the notch24a.

Therefore, the notch24aserves as the bulge suppressing portion24e.

With this configuration, the notch24aof the cylindrical spring pin24is provided to accommodate press-fitting of the nail pin23and thus, press-fitting of the nail pin23is absorbed by the notch24aof the cylindrical spring pin24. Therefore, it is possible to prevent bulging of the outer peripheral surface of the guide part51adue to press-fitting of the nail pin23and also prevent the fixation of the inner peripheral surface of the drive ring3and the outer peripheral surface of the guide part5a.

Therefore, it is no longer necessary to regulate orientation when press-fitting the nail pin and the cylindrical spring pin. This achieves improved easiness of press-fitting work and reduced cost.

This embodiment is also applicable to the case where a pin-shape member other than the nail pin, such as the lock pin and the stopper pin for restricting the opening of the nozzle vane, is press-fitted in the nozzle mount.

A sixth embodiment will be described in reference toFIG. 8A,FIG. 8BandFIG. 8C.

The structure is the same as the first embodiment, except for the configuration of the nozzle mount. Thus, structures other than the nozzle mount will not be described further herein.

In addition, for parts of the same shape with the same effect, are assigned the same reference numerals, and a description thereof will be omitted.

FIG. 8Ais a partial enlarged view of the state where a nail pin according to a sixth embodiment of the present invention is press-fitted in a nozzle mount.FIG. 8Bis a partial enlarged view taken from the lever plate side, before press-fitting of the nail pin into the nozzle mount.FIG. 8Cis a partial enlarged view taken from the lever plate side, after press-fitting of the nail pin into the nozzle mount.

InFIG. 8A, a press-fitting hole53bhas is formed in a nozzle mount53along an axis CL of the nozzle mount53, and a plurality of the press-fitting holes53bis arranged at an outer peripheral part of an end face of a guide part53aat equal intervals in the circumferential direction.

As illustrated inFIG. 8B, a portion is cut off from the outer peripheral surface of the guide part54aof the nozzle mount53in a shape equivalent to a predicted bulge, so as to form a notch53cserving as a bulge suppressing portion. The predicted bulge is an bulge predicted as to a section where the press-fitting hole53band the sliding face side of the drive ring oppose each other, which bulges out of the guide part53aat the press-fitting of the nail pin20.

As illustrated inFIG. 8C, at the press-fitting of the nail pin20into the press-fitting hole53b,the outer peripheral surface of the guide part53ais formed into a smooth circular arc surface.

Therefore, as illustrated inFIG. 8A, by press-fitting the nail pin20into the press-fitting hole53b,the outer peripheral surface of the guide part53abulges outward in the radial direction, thereby making the outer peripheral surface of the guide part53ainto a smooth circular arc surface (seeFIG. 8C) while allowing for an appropriate clearance between the outer peripheral surface of the guide part53aand the inner peripheral surface of the drive ring3.

With this configuration, by predicting in advance a bulge amount of the bulging portion caused by press-fitting the nail pin20and removing this section, it is possible to prevent protrusion of the outer peripheral surface of the guide part53at the press-fitting of the nail pin20and make the outer peripheral surface of the guide part53into a smooth circular arc, thereby preventing fixation between the inner peripheral surface of the drive ring3and the outer peripheral surface of the guide part53a.

Further, it is no longer necessary to regulate orientation when press-fitting the nail pin20. This achieves improved easiness of press-fitting work and reduced cost.

Furthermore, since the nail pin20is press-fitted over the entire pin length (20b), perpendicularity of the nail pin20with respect to the nozzle mount53is stabilized, and it is possible to improve fixing of the nail pin20.

While the embodiment has been described regarding the nail pin20for restricting the drive ring3in the thrust direction. However, the embodiment is also applicable to the stopper pin7which is configured to restrict the lever plate1for varying the vane angle of the nozzle vane2illustrated inFIG. 2when the nozzle vane2reaches a specified closed position, so as to restrict the vane angle of the nozzle vane2below the specified closed position.

Specifically, the embodiment is widely applicable to the case where the structure of press-fitting a pin into the edge of the outer peripheral part is used and a smooth outer peripheral surface is required.

This embodiment is also applicable to the case where a pin-shape member other than the nail pin, such as the lock pin and the stopper pin for restricting the opening of the nozzle vane, is press-fitted in the nozzle mount.

INDUSTRIAL APPLICABILITY

According to the present invention, it is possible to provide a variable displacement exhaust turbocharger equipped with a variable nozzle mechanism, whereby improved durable reliability is achieved by providing the bulge suppressing portion for absorbing a bulging portion generated at press-fitting of the nail pin in the press-fitting hole formed in the nozzle mount along the axial direction, thereby preventing fixation of the inner peripheral surface of the drive ring and the outer peripheral surface of the guide part.