JP2005291152A - Connection construction of compressor impeller and drive shaft, and device with the connection construction - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a connection construction of a compressor impeller and a drive shaft excellent in durability and assembling facility and to provide a device having the connection construction. <P>SOLUTION: This turbo charger is constructed with a bottomed insertion hole 20, not a through hole, formed on a compressor impeller 13 side. This turbo charger causes stress concentration to be hardly generated and allows large improvement of the durability. The drive shaft 15 and the compressor impeller 13 are not screwed together and are connected to each other through interference fit with a fitting hole portion 20A and a fitting shaft portion 15A. This allows assembly to be precisely performed by concentricity of the fitted portions, deformation of the drive shaft, galling of threads and the like are not caused at all and the assembling facility is also satisfactory. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a coupling structure between a compressor impeller and a drive shaft, and an apparatus including the coupling structure.

Conventionally, a compressor impeller constituting an exhaust turbocharger (hereinafter abbreviated as an exhaust turbo) is fixed to a drive shaft provided integrally with a turbine by a nut. That is, the compressor impeller has a through-hole penetrating in the axial direction. The drive shaft is inserted into the through-hole, and a nut is screwed into a threaded portion formed on the tip side of the drive shaft. It was fastened and fixed.
However, in such a coupling structure, since a through hole is provided in the compressor impeller, stress concentration tends to occur in the middle in the axial direction, and there is a limit to improving durability.

In view of this, there has been proposed a coupling structure in which a screw hole with a bottom (a hole not penetrating) along the axial direction is provided in the compressor impeller instead of the through hole, and the drive shaft is screwed into the screw hole (for example, Patent Document 1). Moreover, in this patent document 1, in order to eliminate the rattling of a screwing part or to improve concentricity, the fitting part by the interference fit of a hole and a drive shaft is provided.
According to this coupling structure, since the screw hole may be short enough to ensure that the drive shaft is screwed together, it does not need to be provided to the middle in the axial direction, and stress concentration is unlikely to occur.

Japanese Patent No. 2794338

However, in the coupling structure described in Patent Document 1, when the coupling is performed, the drive shaft is first screwed into the screw hole on the compressor impeller side, and the screws are fitted to each other in the middle of the screwing. For this reason, the concentricity obtained at the screwing portion affects the fitting portion, and there arises a problem that the concentricity that should originally be obtained by the fitting portion is not accurate.
Also, if there is a big difference in concentricity between the screwed part and the fitting part, the screwing will proceed with the rattling of the screwed part, and the drive shaft will be bent overall, etc. There is also the possibility of deformation.
Even when the drive shaft is inserted in a state where the compressor impeller side is heated and the screwed portion or fitting portion on the compressor impeller side is expanded (shrink fit), the drive shaft is not deformed at the time of insertion. Later, as the temperature is returned to room temperature, the effect of the concentricity becomes noticeable, and deformation cannot be avoided.

On the other hand, in order to solve this problem, the interval between the screwing portion and the fitting portion is lengthened, and when the drive shaft is inserted into the screw hole, the base end side is first fitted to each other, and the fitting is advanced. It is also conceivable to start screwing on the tip side while going.
However, since the interval between the screwed portion and the fitting portion is increased, the screw hole is naturally increased, and stress concentration is likely to occur as before. Also, if the concentricity of the mating part and the screwing part is deviated, the concentricity at the mating part is given priority, so that the screwing does not work as expected and the screwing is forced. There is still the possibility of gnawing the screw threads or deforming them as a whole. The same is true when they are joined by shrink fitting.

  An object of the present invention is to provide a coupling structure between a compressor impeller and a drive shaft, which is excellent in durability and assemblability, and an apparatus including the coupling structure.

The coupling structure of the compressor impeller and the drive shaft according to claim 1 of the present invention is:
A projection provided on the back side of the compressor impeller, and a bottomed drive shaft insertion hole provided in the axial direction from the projection, and the insertion hole and the drive shaft are fitted with an interference fit. It is characterized by being connected only by the combination.

  The coupling structure of the compressor impeller and the drive shaft according to claim 2 of the present invention is the coupling structure of the compressor impeller and the drive shaft according to claim 1, wherein the compressor impeller and the drive shaft are connected in the rotational direction. A slip suppression means for suppressing slippage between each other is provided.

  The compressor impeller and drive shaft coupling structure according to claim 3 of the present invention is the compressor impeller and drive shaft coupling structure according to claim 1 or 2, wherein the compressor impeller and the drive shaft include: The omission control means which suppresses the omission | missing between the axial directions is provided.

  According to a fourth aspect of the present invention, there is provided a coupling structure between the compressor impeller and the drive shaft. In the coupling structure between the compressor impeller and the drive shaft according to the third aspect, the drop prevention means reduces the diameter or expands at a predetermined temperature or higher. It is characterized by including a snap ring made of a shape memory alloy to be diameterd.

  The compressor impeller and drive shaft coupling structure according to claim 5 of the present invention is the compressor impeller and drive shaft coupling structure according to claim 4, wherein the shape transformation temperature of the snap ring is the compressor impeller and the drive shaft. It is characterized by being higher than the practical operating temperature of the drive shaft.

  A coupling structure between a compressor impeller and a drive shaft according to a sixth aspect of the present invention is the coupling structure between the compressor impeller and the drive shaft according to any one of the first to fifth aspects. And a sleeve and a thrust collar, or an integrated member of the sleeve and the thrust collar is pressed and clamped between the step portion provided on the outer peripheral portion of the drive shaft.

  On the other hand, an apparatus according to a seventh aspect of the present invention is characterized by including the coupling structure of the compressor impeller and the drive shaft according to any one of the first to sixth aspects.

  As described above, according to the first aspect of the present invention, since a bottomed insertion hole is provided on the compressor impeller side instead of a through hole, stress concentration hardly occurs, and durability is improved. In addition, the drive shaft and the compressor impeller are not screwed together, but are coupled with each other only by interference fit. As a result, no galling or the like occurs in the thread portion and the assemblability is good.

According to the second aspect of the present invention, since the slip suppression means is provided so that slip does not occur between the compressor impeller and the drive shaft, the compressor impeller is prevented from rotating, and idling on the drive shaft side is prevented.
Here, as the slip suppression means, it is conceivable that the drive shaft side is processed to have a two-sided width, other cross-sectional polygonal shape, or non-circular cross-sectional shape so that the compressor impeller side is engaged with this part. .

According to the third aspect of the present invention, the disengagement preventing means is provided so that the disengagement between the compressor impeller and the drive shaft does not occur, so that the compressor impeller is disengaged from the drive shaft and the contact with the surrounding, for example, the housing is reliably prevented. Become so.
Note that the disengagement suppressing means does not compensate for the frictional force of the fitting portion, and may be a simple one such as a snap ring.

According to the invention of claim 4, since the snap ring is made of a shape memory alloy that is deformed at a predetermined temperature or higher, when the coupling between the compressor impeller and the drive shaft is released to disassemble each other, only these are heated. Well, a strong pulling force or the like is unnecessary, and it can be easily disassembled.
In addition, as such a snap ring, Ti-Ni base ternary high-temperature shape memory alloy etc. which added Au (gold), Pd (palladium), Zr (zirconium), Hf (haonium) etc. to Ti-Ni alloy etc. Can be used.

  According to the invention of claim 5, since the shape transformation temperature of the snap ring is higher than the practical use temperature of the compressor impeller and the drive shaft, the compressor impeller is operated during normal operation of the device to which the coupling structure is applied. There is no worry that the drive shaft will come off and it will only come off when heated.

According to the sixth aspect of the present invention, the sleeve and the thrust collar are pressed and clamped between the end surface of the compressor impeller and the stepped portion of the drive shaft, so that these members rotate together with the compressor impeller and the drive shaft more reliably. And the seizure or the like of them is prevented.
At this time, by applying the slip suppression means of claim 2 also to the sleeve and the thrust collar, the integral rotation is more reliably performed.
It should be noted that the present invention can be applied even when the sleeve and the thrust collar are formed of an integral member as required.

  According to the seventh aspect of the invention, the above-described object of the present invention can be achieved because the coupling structure of the compressor impeller and the drive shaft is applied.

  Hereinafter, each embodiment of the present invention will be described with reference to the drawings. In the second embodiment and later described below, the same members as those in the first embodiment described below are denoted by the same reference numerals, and detailed description thereof in the second and subsequent embodiments is omitted or simplified.

[First Embodiment]
FIG. 1 is a cross-sectional view showing a turbocharger 1 to which a coupling structure of a compressor impeller 13 and a drive shaft 15 according to a first embodiment of the present invention is applied, and FIG. 2 is a cross-sectional view showing a main part of the turbocharger 1. It is.

  The turbocharger 1 is mounted on, for example, a gasoline engine or a diesel engine, and includes a compressor 11 connected in the middle of an intake pipe to an engine (not shown) and an exhaust turbine 12 connected in the middle of an exhaust pipe. With. The compressor 11 has a compressor impeller 13 that compresses intake air from the outside by rotating. The exhaust turbine 12 has a turbine wheel 14 that is rotated by inflowing exhaust gas. The turbine wheel 14 and the compressor impeller 13 are coupled by a drive shaft 15 and are rotatably supported by a housing 16. Yes. The drive shaft 15 is made of steel integrally cast with the turbine wheel 14, and the compressor impeller 13 is an aluminum casting.

Hereinafter, a connecting portion between the compressor impeller 13 and the drive shaft 15 will be described in detail.
At the center of the back side of the compressor impeller 13, that is, the center of the side facing the turbine wheel 14, a projection 19 that protrudes toward the turbine wheel 14 is provided. An insertion hole 20 is provided from the protrusion 19 toward the back side in the axial direction.

  The insertion hole 20 is a hole for inserting the drive shaft 15, but is a bottomed hole, not a conventional through hole that penetrates the compressor impeller 13. Further, as shown in FIG. 2 in an enlarged manner, the insertion hole 20 is a fitting hole portion 20A having a circular cross section on the back side, a drum-shaped drum having a larger diameter on the opening side and two shallow parallel surfaces. It is an engagement hole 20B. A chamfered chamfer surface 20C is formed between the fitting hole 20A and the engagement hole 20B.

  On the tip side of one drive shaft 15, there is provided a fitting shaft portion 15A that is inserted into the insertion hole 20 of the compressor impeller 13 and engages with the fitting hole portion 20A. An engagement shaft portion 15B that engages with the engagement hole portion 20B is provided on the end side.

  The fitting state between the fitting shaft portion 15A and the fitting hole portion 20A is an interference fit by shrink fitting. That is, the aluminum compressor impeller 13 is heated to about 150 ° C. to expand the diameter of the fitting hole 20A, and the steel drive shaft 15 (integrated with the turbine wheel 14) is fitted between them to bring it to room temperature. Return to reduce diameter for an interference fit. In addition to this, there is no conventional screwing structure, and the compressor impeller 13 and the drive shaft 15 are coupled only by fitting.

  A substantially C-shaped snap ring 21 is attached to the circumferential groove 15C provided in the fitting shaft portion 15A. The snap ring 21 is made of a shape memory alloy and has an appropriate elastic force in the range of the practical temperature of the turbocharger 1 and is maintained at the illustrated diameter, but exceeds the practical temperature of the turbocharger 1. For example, the diameter is reduced from about 150 ° C. (predetermined temperature) to about 600 ° C. and buried in the circumferential groove 15C.

  Therefore, when the fitting shaft portion 15A is fitted into the fitting hole portion 20A, the snap ring 21 is fitted into the circumferential groove 15C at a normal temperature and inserted into the heated compressor impeller 13 as it is. After the diameter is reduced by abutting against the chamfer surface 20C, the diameter is increased and locked when reaching the circumferential groove 20D on the fitting hole 20A side. Thus, the compressor impeller 13 does not come off from the drive shaft 15. That is, the snap ring 21 and the circumferential grooves 15C and 20D constitute the drop prevention means 22 of the present invention.

  On the other hand, when the compressor impeller 13 is removed from the drive shaft 15, the compressor impeller 13 is heated to 150 ° C. or more together with the drive shaft 15 side, whereby the snap ring 21 is also heated to reduce the diameter, and the circumference It is possible to release the locking state with the groove 20D and to extract the compressor impeller 13.

  The engaging shaft portion 15B has a so-called two-surface width and has a pair of parallel engaging surfaces 15D. The entire outer peripheral portion including the engagement surface 15D is engaged with the engagement hole 20B. As a result, the compressor impeller 13 and the drive shaft 15 are prevented from slipping relative to each other in the rotational direction and do not idle. That is, the slip restraining means 23 of the present invention is constituted by the flat engagement surface 15D that forms this two-surface width and the engagement hole portion 20B that engages with the flat engagement surface 15D.

  By the way, the engagement surface 15D having a two-surface width is continuously formed with a predetermined length toward the base end side. The sleeve 24 and the thrust collar are pressed between the engagement surface 15D and the outer peripheral portion of this portion by the end surface 19A of the projection 19 of the compressor impeller 13 and the stepped portion 15E on the base end side of the two-surface width. 25 is arranged. At the same time that the compressor impeller 13 is fitted to the drive shaft 15 by an interference fit, the sleeve 24 and the thrust collar 25 are sandwiched. At this time, the snap ring 21 and the circumferential groove 20D described above are locked to each other by a tapered surface, and the compressor impeller 13 is also pressed against the sleeve 24 by this tapered surface, thereby improving the clamping force. Is planned.

  In the coupling structure described above, the compressor impeller 13, the drive shaft 15 (turbine wheel 14), the sleeve 24, and the thrust collar 25 rotate together. These are supported by a full float bearing 26 (FIG. 1) in the radial direction and supported by a thrust bearing 27 disposed between the sleeve 24 and the thrust collar 25 in the thrust direction. Further, as shown in FIG. 2, the compressor impeller 13 side is oil-sealed by a double seal ring 29 that is fitted into the sleeve 24 and held by the holding ring 28.

According to this embodiment, there are the following effects.
(1) That is, in the turbocharger 1, since the bottomed insertion hole 20 is provided on the compressor impeller 13 side, stress concentration is less likely to occur, and durability is greatly improved. Can do. In addition, the drive shaft 15 and the compressor impeller 13 are not screwed together, but the fitting hole portion 20A and the fitting shaft portion 15A are coupled with each other only by an interference fit. The parts can be assembled with high accuracy due to the concentricity of the parts, and the drive shaft is not deformed and the thread parts are not galvanized at all.

(2) Further, since the disengagement suppression means 22 using the snap ring 21 is provided so that the compressor impeller 13 does not come off from the drive shaft 15, it is possible to prevent the compressor impeller 13 from coming off from the drive shaft 15, and the housing It is possible to prevent damage and the like by reliably preventing contact with the inside.

(3) At this time, since the snap ring 21 is made of a shape memory alloy that deforms at a predetermined temperature or higher, when the compressor impeller 13 is detached from the drive shaft 15 and disassembled, it is only necessary to heat them to the temperature or higher. This eliminates the need for a strong pulling force and can be easily disassembled. Moreover, since the compressor impeller 13 is made of aluminum and has a larger thermal expansion coefficient than the steel drive shaft 15, the diameter of the insertion hole 20 can be increased by heating, and the compressor impeller 13 can be removed more easily. .

(4) Since the shape transformation temperature of the snap ring 21 is higher than the practical use temperature of the compressor impeller 13 and the drive shaft 15, the compressor impeller 13, the drive shaft 15, Can be removed by heating only during decomposition.

(5) Further, slip prevention means comprising a flat engagement surface 15D forming a two-surface width and an engagement hole portion 20B engaged with the two so as to prevent slippage between the compressor impeller 13 and the drive shaft 15. Since 23 is provided, the compressor impeller 13 can be reliably prevented from rotating and the idling on the drive shaft 15 side can be prevented. Moreover, since the engagement surface 15D has a simple structure, it can be easily formed by milling or the like.

(6) In addition, since the sleeve 24 and the thrust collar 25 are also engaged with the engagement surface 15D of the drive shaft 15, the sleeve 24 and the thrust collar 25 are rotated together with the drive shaft 15 with certainty. be able to.

(7) The sleeve 24 and the thrust collar 25 are not only engaged with the engagement surface 15D of the drive shaft 15 but also pressed between the end surface 19A of the compressor impeller 13 and the step portion 15E of the drive shaft 15. Since they are clamped, they can be integrally rotated with the compressor impeller 13 and the drive shaft more reliably, and seizure of the sleeve 24 and the thrust collar 25 can be prevented.

[Second Embodiment]
FIG. 3 shows a second embodiment of the present invention.
In the present embodiment, a sleeve collar (integral member) 30 in which a sleeve and a thrust collar are integrated is used, and accordingly, the thrust bearing 27 has a horseshoe shape as shown in FIG. Further, instead of the snap ring, a plurality (only one is shown in FIG. 3) of ball latches (disengagement suppressing means) 31 having a steel ball biased by a spring or the like is provided around the fitting shaft portion 15A. This is different from the first embodiment. Other configurations are the same as those of the first embodiment.

Here, in the present embodiment, a thrust bearing 27 is fitted into the sleeve collar 30 from the radial direction, and the fitted sleeve collar 30 is accommodated in the housing 16. Is inserted into the drive shaft 15 and the compressor impeller 13 is fitted.
In FIG. 4, reference numeral “27 </ b> A” is a pad portion that contacts the sleeve collar 30, and reference numeral “27 </ b> B” is a tapered land portion that interposes lubricating oil with the sleeve collar 30.

In this embodiment, the effects (3) and (4) described above cannot be obtained, but other effects can be obtained in the same manner with the same or similar configuration as the first embodiment. In addition, the present embodiment has the following effects.
(8) That is, since the sleeve collar 30 has a shape in which the sleeve and the thrust collar are integrated, it is only necessary to prepare this one part, and the number of parts can be reduced.

(9) Since the thrust bearing 27 has a horseshoe shape, even when the sleeve collar 30 is used, the thrust bearing 27 can be fitted into the sleeve collar 30 without any trouble.

[Third Embodiment]
FIG. 5 shows a third embodiment of the present invention.
In the present embodiment, the sleeve 24 is engraved with an internal thread portion 24A, and the drive shaft 15 is engraved with an external thread portion 15F and screwed together. The thrust collar 25 is pressed against the step portion 15E by this screwing. Therefore, the end surface 19 </ b> A of the compressor impeller 13 does not sandwich the sleeve 24 and the thrust collar 25 and does not contact the sleeve 24. Further, the engagement surface 15D having a two-surface width is provided between the fitting shaft portion 15A and the male screw portion 15F. Other configurations are the same as those of the first embodiment or the second embodiment.

Such an embodiment has the following effects due to its unique configuration.
(10) Since the thrust collar 25 is clamped by screwing the sleeve 24 onto the drive shaft 15 and tightening, the sleeve 24 is clamped by the compressor impeller 13 as compared with the structure of clamping the sleeve 24 together with the compressor impeller 13. There is no need to press, and the fitting state between the fitting shaft 15A and the fitting hole 20A can be maintained better.

In addition, this invention is not limited to the said embodiment, Including other structures etc. which can achieve the objective of this invention, the deformation | transformation etc. which are shown below are also contained in this invention.
For example, in each of the above embodiments, the sleeve 24 and the thrust collar 25 are sandwiched by using the compressor impeller 13 or the thrust collar 25 is sandwiched by screwing the sleeve 24. As described above, the sleeve 24 and the thrust collar 25 may be sandwiched between the step portion 15E by the snap ring 32.
In FIG. 6, the snap ring 32 has a biasing force in the direction of reducing the diameter, and is once expanded and fitted into the circumferential groove 15G. Further, in order to press the sleeve 24 and the thrust collar 25 in the fitted state, the snap ring 32 and the circumferential groove 15G are respectively formed with tapered surfaces.

  According to the previous embodiment, the snap ring 21 constituting the drop prevention means 22 is reduced in diameter at a predetermined temperature or higher, but may be increased in diameter at a predetermined temperature. When the compressor impeller 13 is heated and removed, the snap ring comes to be accommodated in the circumferential groove 20D on the fitting hole 20A side, and comes off together with the compressor impeller 13.

  In the above embodiment, an example in which the coupling structure of the compressor impeller and the drive shaft of the present invention is applied to a turbocharger has been shown. However, the coupling structure of the present invention is not limited to a turbocharger, and any fluid (gas, liquid, etc.) It may be applied to a pump or the like that pumps air, or may be applied to a blower for air conditioning.

The best configuration, method and the like for carrying out the present invention have been disclosed in the above description, but the present invention is not limited to this. That is, the invention has been illustrated and described primarily with respect to particular embodiments, but may be configured for the above-described embodiments without departing from the scope and spirit of the invention. Various modifications can be made by those skilled in the art in terms of quantity, other details, and the like.
Therefore, the description limited to the shape, quantity and the like disclosed above is an example for easy understanding of the present invention, and does not limit the present invention. The description by the name of the member which remove | excluded the limitation of one part or all of such restrictions is included in this invention.

  The present invention can be used for a turbocharger attached to an internal combustion engine, a pump for pumping an arbitrary fluid, a blower for air conditioning, and the like.

Sectional drawing which shows the apparatus with which the coupling structure of the compressor impeller and drive shaft which concerns on 1st Embodiment of this invention was applied. Sectional drawing which shows the principal part of the said 1st Embodiment. Sectional drawing which shows 2nd Embodiment of this invention. The front view which shows the member used for the said 2nd Embodiment. Sectional drawing which shows 3rd Embodiment of this invention. Sectional drawing which shows the modification of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Turbocharger (apparatus), 13 ... Compressor impeller, 15 ... Drive shaft, 15E ... Step part, 19 ... Projection part, 20 ... Insertion hole, 21 ... Snap ring, 22 ... Drop prevention means, 23 ... Slip prevention means, 24 ... Sleeve, 25 ... Thrust collar, 30 ... Sleeve collar (integral member), 31 ... Ball latch (disengagement suppressing means).

Claims (7)

In the coupling structure of the compressor impeller (13) and the drive shaft (15),
A protrusion (19) provided on the back side of the compressor impeller (13);
A bottomed drive shaft insertion hole (20) provided along the axial direction from the protrusion (19),
The coupling structure of the compressor impeller (13) and the drive shaft (15), wherein the insertion hole (20) and the drive shaft (15) are coupled only by an interference fit. In the coupling structure of the compressor impeller (13) and the drive shaft (15) according to claim 1,
The compressor impeller (13) and the drive shaft (15) are provided with slip suppression means (23) for suppressing slippage between them in the rotational direction. Connection structure with the shaft (15). In the coupling structure of the compressor impeller (13) and the drive shaft (15) according to claim 1 or 2,
The compressor impeller (13) and the drive shaft (15) are provided with a slip prevention means (22) for restraining slippage in the axial direction between the compressor impeller (13) and the drive shaft (15). Connection structure with the shaft (15). In the coupling structure of the compressor impeller (13) and the drive shaft (15) according to claim 3,
The drop prevention means (22) includes a snap ring (21) made of a shape memory alloy that reduces or expands in diameter at a predetermined temperature or higher. A compressor impeller (13) and a drive shaft ( 15) A bonded structure. In the coupling structure of the compressor impeller (13) and the drive shaft (15) according to claim 4,
The shape transformation temperature of the snap ring (21) is higher than the practical use temperature of the compressor impeller (13) and the drive shaft (15). The compressor impeller (13) and the drive shaft (15) Bond structure. In the coupling structure of the compressor impeller (13) and the drive shaft (15) according to any one of claims 1 to 5,
A sleeve (24) and a thrust collar (25) are pressed between a protrusion end surface (19A) of the compressor impeller (13) and a stepped portion (15E) provided on an outer peripheral portion of the drive shaft (15). The combined structure of the compressor impeller (13) and the drive shaft (15), wherein the integrated member (30) of the sleeve and the thrust collar is pressed and clamped.   A device (1) comprising a coupling structure of the compressor impeller (13) according to any one of claims 1 to 6 and a drive shaft (15).

Images