JP2012149612A - Variable displacement turbocharger, and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a variable displacement turbocharger that prevents abnormal wear of a sliding part, and a method of manufacturing the same.SOLUTION: The variable displacement turbocharger includes a nozzle blade angle adjusting ring 32 for adjusting a blade angle of a nozzle vane 30 of a turbine 21, and a crank lever 33 for turning the nozzle blade angle adjusting ring 32 outside a turbine housing 26. A coating 10 with tungsten disulfide particles, graphite and antimony trioxide dispersed in silicon resin is formed on a locking portion between a slot 32a of the nozzle blade angle adjusting ring 32 and the crank lever 33.

Description

  The present invention relates to a variable displacement turbocharger having a nozzle vane with variable blade angle in a turbine, and more particularly, a variable displacement turbocharger with improved wear resistance of a nozzle blade angle adjusting ring for adjusting the blade angle of the nozzle vane and its manufacture. It is about the method.

  A turbocharger is installed in a diesel engine for a vehicle. Generally, a fixed capacity (conventional) turbocharger is used. However, since 2011, regulations will be strengthened in North America and Europe. In order to apply, it has been decided to adopt a variable capacity turbocharger (referred to as VNT or VGT) instead of a fixed capacity.

  The conventional variable capacity turbocharger mounted on the vehicle diesel engine is one in which nozzle vanes are provided on the turbine side as shown in Patent Documents 1 and 2 to control the exhaust gas flow rate. explain.

  As shown in FIG. 7, the variable capacity turbocharger 20 is configured by connecting a turbine 21 and a compressor 22 with a bearing housing 29, and the turbine 21 is provided with a turbine capacity variable mechanism 24.

  The turbine 21 includes a turbine impeller 25 and a turbine housing 26 that surrounds the turbine impeller 25 and into which exhaust gas is introduced. The compressor 22 surrounds the compressor impeller 27 and the compressor impeller 27, and a compressor housing 28 that introduces intake air. It consists of. The turbine impeller 25 and the compressor impeller 27 are connected by a turbo shaft 23, and the turbo shaft 23 is accommodated in a bearing housing 29 and supported by a bearing portion (not shown) provided in the bearing housing 29.

  As shown in FIGS. 5 to 7, the turbine capacity varying mechanism 24 includes a large number of nozzle vanes 30 provided at variable intervals along the circumferential direction of the nozzle throat portion 26 a of the turbine housing 26, and these nozzle vanes. Nozzle blade angle adjustment ring 32 connected 30 through a link plate 31, and a crank lever 33 for engaging the groove 32 a of the nozzle blade angle adjustment ring 32 and rotating the nozzle blade angle adjustment ring 32, A crankshaft 34 coupled to the crank lever 33 and extending out of the turbine housing 26; a control link 35 coupled to the extended crankshaft 34 for rotating the crankshaft 34; and the control link And a driving device 36 composed of a motor for driving 35.

  As shown in FIG. 6, the control link 35 includes a first drive lever 37 connected to the drive device 36, a second drive lever 38 connected to the crankshaft 34, and first and second drive levers 37, 38. The control rod 40 includes link pins 39a and 39b to be connected.

  As shown in FIG. 7, the blade capacity of the nozzle vane 30 is adjusted by the turbine capacity varying mechanism 24. As a result, the control rod 40 reciprocates when the drive device 36 rotates by a predetermined angle, whereby the crankshaft 34 rotates by a predetermined angle. At the same time, the crank lever 33 rotates and the nozzle blade angle adjustment ring 32 rotates by a predetermined angle, whereby the blade angle of the nozzle vane 30 is adjusted via the link plate 31, and the nozzle throat portion 26a is moved from the turbine housing 26. The rotational speed of the turbine impeller 25 can be varied by adjusting the inflow angle and the capacity of the exhaust gas flowing into the turbine impeller 25 through the turbine impeller 25.

Japanese Patent Laid-Open No. 05-296053 JP 2004-270472 A

  By the way, although the nozzle blade angle adjustment ring 32 is provided outside the turbine housing 26, it is exposed to a high temperature of 300 ° C. or higher even in the atmosphere outside the turbine housing 26. The sliding portion between the groove 32a of the ring 32 and the crank lever 33 for rotating the nozzle blade angle adjusting ring 32 has a problem that the frictional resistance increases. In particular, this sliding portion has a high contact stress because of the resultant force acting on the large number of nozzle vanes 30 that adjust the throttle amount of the exhaust gas introduction amount inside.

  Conventionally, the nozzle blade angle adjustment ring 32 and the crank lever 33 are formed of SUS, and the sliding surfaces thereof are chromized (surface hardening treatment with chromium element) or hardening treatment, nitriding, DLC coating (diamond-like coating) ), Trivalloy T400 alloy (registered trademark), Hastelloy (registered trademark), and the like have been proposed.

  However, there is a problem that even if the material strength is enhanced, mechanical friction is inevitable because it is used in a high temperature environment, and abnormal wear cannot be prevented.

  Accordingly, an object of the present invention is to provide a variable capacity turbocharger that can solve the above-described problems and can prevent abnormal wear even if sliding portion wears, and a method of manufacturing the same.

  In order to achieve the above object, a first aspect of the present invention is a variable capacity turbocharger including a nozzle blade angle adjusting ring for adjusting a blade angle of a nozzle vane of a turbine and a crank lever for rotating the nozzle blade angle adjusting ring outside the turbine housing. In the charger, a variable-capacity turbocharger characterized in that a film in which tungsten disulfide particles, graphite, and antimony trioxide are dispersed in silicon resin is formed at the engaging portion between the nozzle blade angle adjusting ring groove and the crank lever. It is a charger.

  According to a second aspect of the present invention, there is provided a variable capacity turbocharger manufacturing method including a nozzle blade angle adjusting ring for adjusting a blade angle of a nozzle vane of a turbine and a crank lever for rotating the nozzle blade angle adjusting ring outside the turbine housing. 40-50 parts by mass of resin, 30-40 parts by mass of tungsten disulfide particles, 6-10 parts by mass of graphite, and 10-20 parts by mass of antimony trioxide. A binder is added to this, and the nozzle blade angle is adjusted. A variable capacity characterized in that it is applied to the ring groove and the sliding surface of the crank lever and then dried, this is repeated several times, and the film thickness is adjusted to 30 ± 10 μm, followed by firing to form a film. This is a method of manufacturing a turbocharger.

  A third aspect of the present invention is the method of manufacturing a variable capacity turbocharger according to the second aspect, wherein the coating is formed after the outer peripheral surface of the sliding surface is subjected to chromization or nitriding.

  The present invention forms on the sliding surface a film in which tungsten disulfide, graphite, and antimony trioxide are dispersed in a silicone resin, so that the sliding property is high and the wear resistance is excellent even in a high temperature environment. The nozzle blade angle adjustment ring structure can be used as a variable capacity turbocharger.

It is a figure which shows one Embodiment of the nozzle blade angle adjustment ring structure of the variable capacity | capacitance turbocharger of this invention. It is a figure explaining the abrasion resistance and sliding property of the film | membrane formed in the sliding surface of the nozzle blade angle adjustment ring structure of the variable capacity | capacitance turbocharger of this invention. It is a figure which shows the abrasion resistance test result in this invention and a prior art example. It is a figure explaining abrasion of the sliding surface in the past. It is a perspective view which shows the detail of the nozzle vane and nozzle blade angle adjustment ring structure of a variable capacity | capacitance turbocharger. It is a perspective view which shows the detail of the control link of a variable capacity | capacitance turbocharger. It is a whole sectional view of a variable capacity turbocharger.

  A preferred embodiment of the present invention will be described below in detail with reference to the accompanying drawings.

  First, the basic configuration of the variable capacity turbocharger is as described with reference to FIGS.

  FIG. 1 shows the nozzle blade angle adjusting ring structure of the variable capacity turbocharger of the present invention. FIG. 1 (a) is an overall perspective view of the nozzle blade angle adjusting ring structure, and FIG. FIG. 1C is a perspective view of the main part of the nozzle blade angle adjusting ring 32, and FIG. 1C is a perspective view of the main part of the crank lever 33.

  As shown in FIG. 1B, the nozzle blade angle adjustment ring 32 is formed with a groove 32 a that engages with the crank lever 33. As shown in FIG. 1C, the crank lever 33 includes an engagement pin 33a that engages with the groove 32a of the nozzle blade angle adjustment ring 32, and a boss portion 33b that is connected to the crankshaft 34 (FIGS. 6 and 7). Have

  In the present invention, the wear resistance and self-sufficiency are provided on both the sliding surface on the inner surface of the groove 32a of the nozzle blade angle adjusting ring 32 and the outer peripheral surface of the engaging pin 33a of the crank lever 33, or on one of the sliding surfaces. A film 10 having lubricity is formed.

  Further, these sliding surfaces are subjected to chromization treatment and nitriding treatment before the film formation, and the film 10 is formed on the outer peripheral surface of the hardened layer.

The component of this film 10 is
(A) Silicon resin 40-50 mass parts (B) Tungsten disulfide particle 30-40 mass parts (C) Graphite 6-10 mass parts (D) It consists of 10-20 mass parts antimony trioxide.

  (A) As the silicon resin, one having a polysiloxane bond (Si—O—Si) as a main skeleton, having heat resistance exceeding a heat resistant temperature of 300 ° C., and having a low degree of polymerization is used.

  (B) Tungsten disulfide particles are particles having excellent self-lubricating properties, and those having an average particle size of 1 to 2 μm are used.

  (C) As graphite, it is preferable because it has excellent self-lubricating property and has lubricity even if it is worn away and peeled off from the film, and has an average particle diameter of 1 to 2 μm.

  (D) Antimony trioxide is added as a lubricating auxiliary agent and wear resistance as an improver.

  An inorganic binder is added to the components (A) to (D) to form a film-forming resin.

  A coating film is formed on the sliding surface (the inner surface of the groove 32a, the outer peripheral surface of the engaging pin 33a) with this film-forming resin by spray coating or the like, and then heated and dried at 70 to 90 ° C. for 20 minutes or more. This spray coating and drying are repeated 3 to 5 times, and finally a coating film having a thickness of 30 ± 10 μm, preferably 30 μm is formed, and then the coating film is baked by baking at 230 ° C. ± 10 ° C. for 60 minutes. 10 is formed.

The characteristics of this film 10 are
Friction coefficient 0.06 (typical value)
Cross-cut test 100/100 (JIS K 5400)
Pencil hardness 5H
Heat resistance No change after heating at about 600 ° C. for 30 minutes.

  In addition, the coating is performed after the inner surface of the groove 32a, the outer peripheral surface of the engaging pin 33a, the curing process such as the chromizing process or the nitriding process, and the hardened layer is sandblasted to roughen the surface, and then the coating is performed. Good.

  Next, the operation of the film 10 will be described.

  First, FIG. 4 shows a state of the inner peripheral surface of the groove 32a of the conventional nozzle blade angle adjustment ring 32 and the outer peripheral surface of the engagement pin 33a of the crank lever 33, which are not formed with a film.

  In this conventional example, even if the surface of the groove 32a (or the engaging pin 33a) is subjected to nitriding treatment, the processing roughness of micron order remains, and the sliding surface is not in a state of being in uniform contact, As shown to Fig.4 (a), it exists in the state which the top part used as the maximum height was in point contact with the internal peripheral surface. Therefore, if the contact stress due to friction, vibration, or the like is high in the state of FIG. 4A, a micro fracture occurs from the point-contacted portion 32p, and the contact portion is lost and damaged as shown in FIG. 4B. It disappears from the sliding surface as a piece 32B, and then contact and destruction of the high portion 32p occur sequentially, and wear progresses rapidly unlike normal friction, and the hardened layer subjected to the surface hardening treatment disappears. I found out.

  On the other hand, in the present invention, the above-described abnormal wear can be prevented by forming the film 10.

  This will be described with reference to FIG.

  FIG. 2 shows an enlarged schematic view of the cross section of the coating 10 formed in the groove 32a (or the engagement pin 33a).

  First, as shown in FIG. 2 (a), immediately after the formation of the coating 10, the groove 32a (or the engagement pin 33a) in which the coating 10 in which tungsten disulfide particles 11B and graphite 11C are dispersed is formed in the silicon resin 11A. In this state, the contact is made with the inner peripheral surface of the engagement pin 33a (or the groove 32a).

  Thus, by including the tungsten disulfide particles 11 </ b> B and the graphite 11 </ b> C in the film 10, the sliding performance of the sliding surface is good even at high temperatures.

  Next, as shown in FIG. 2B, during the use of the coating 10, the tungsten disulfide particles 11B and the graphite 11C are sequentially released from the sliding surface due to wear and wear gradually.

  Further, as wear progresses as shown in FIG. 2 (c), the high portion 32p (or 33p) of the surface of the groove 32a (or the engagement pin 33a) begins to be exposed from the silicon resin 11A, but the tungsten disulfide particles 11B and Since the graphite 11C is a solid lubricant, the gradual contact wear does not proceed as described with reference to FIG. 4, but slight wear occurs in the sequentially exposed portions, and finally FIG. 2 (d). As shown in FIG. 4, the entire surface is in a mirror surface 32M (or 33M) polished by lapping, and surface contact is achieved without supporting the contact force locally, so that the wear rate can be dramatically improved.

  In addition, the mirror-like finish processing as described above is technically possible by cutting + polishing + lapping in the initial stage of assembly, but considering the posture error during assembly and the variation of the mating parts, Realization of contact is difficult.

  Although there is a method such as matching polishing, it is still difficult to carry out in a state where a large number of parts are combined such as the nozzle blade angle adjusting ring 32 and the crank lever 33.

  Thus, in the present invention, the coating 10 made of silicon resin is formed on the sliding surface of the groove 32a of the nozzle blade angle adjusting ring 32 and the engaging pin 33a of the crank lever 33. Tungsten disulfide or graphite dispersed in the silicon resin becomes a solid lubricant, which eliminates the problem of surface roughness and finally allows the sliding surface to be in a mirror-finished state.

  Next, the results of actual life tests in the accelerated rig test using the nozzle blade angle adjusting ring 32 and the crank lever 33 of the present invention and the conventional example will be described with reference to FIG. At this time, the vibration inlet was made from the blade angle adjusting ring 32 side which is a turbo mounting portion.

  In FIG. 3, in the present invention and the conventional example, the nozzle blade angle adjustment ring 32 and the crank lever 33 are both SUS, and the sliding surface is subjected to SUS + nitriding treatment of the base (the treatment layer is evaluated to be approximately 50 μm). In the present invention, a film was formed after nitriding, and in the conventional example, no coating was formed.

  As a result, in the conventional example, the wear life is 0.3289 (mm) at the life and the wear time is 789 (hr), whereas the wear at the life is 0.3289 (mm) in the present invention. ), The lifetime was 2691 (hr), and it was confirmed that the life could be increased by 3.4 times when worn.

  3 that the initial wear rate is greatly reduced and the steady wear rate can be improved to about 1/3 of the conventional example.

DESCRIPTION OF SYMBOLS 10 Film | membrane 24 Turbine capacity variable mechanism 30 Nozzle vane 32 Nozzle blade angle adjustment ring 32a Groove 33 Crank lever 33a Engagement pin

Claims (3)

  In a variable capacity turbocharger having a nozzle blade angle adjusting ring for adjusting a blade angle of a turbine nozzle vane and a crank lever for rotating the nozzle blade angle adjusting ring outside the turbine housing, a groove of the nozzle blade angle adjusting ring, a crank lever, A variable capacity turbocharger characterized in that a coating film in which tungsten disulfide particles, graphite, and antimony trioxide are dispersed in a silicon resin is formed at the engaging portion.   In a method for manufacturing a variable capacity turbocharger having a nozzle blade angle adjusting ring for adjusting a blade angle of a nozzle vane of a turbine and a crank lever for rotating the nozzle blade angle adjusting ring outside the turbine housing, 40 to 50 parts by mass of silicon resin 30 to 40 parts by mass of tungsten disulfide particles, 6 to 10 parts by mass of graphite, and 10 to 20 parts by mass of antimony trioxide. A binder is added to this, and this is added to the groove of the nozzle blade angle adjusting ring and the crank lever. A method for producing a variable capacity turbocharger, characterized in that the coating is applied to the sliding surface and then dried, and this is repeated several times to obtain a coating thickness of 30 ± 10 μm and then fired to form a coating.   The manufacturing method of the variable capacity | capacitance turbocharger of Claim 2 which formed the said film | membrane after performing the chromization process or the nitriding process on the outer peripheral surface of the said sliding surface.