JP2009209731A - Method for measuring axial force of turbine shaft and supercharger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for measuring axial force of a turbine shaft and a supercharger capable of (1) accurately measuring axial force acting on the turbine shaft when a compressor impeller is fixed on the turbine shaft with using a fastener, (2) assembling the supercharger to satisfy desired performances, and (3) reducing individual differences of performances of the supercharger. <P>SOLUTION: This invention relates to a method for measuring axial force acting on the turbine shaft 2 when an insertion part 2b which is formed on one end side of the turbine shaft 2 and has a screw part 2d formed at a tip part is inserted in a compressor impeller 4 and the compressor impeller 4 is pressed and fixed on a receiving surface 2c formed between one end and another end of the turbine shaft 2 by a fastening nut 5 screwed on the screw part 2d. The insertion part 2b is inserted in the compressor impeller 4, pressed and fixed under a condition where strain gauges 6, 7 are provided on a surface of the insertion part 2b beforehand. Axial force is measured based on strain indicated by the strain gauges 6, 7. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for measuring an axial force of a turbine shaft and a supercharger.

Patent Documents 1 and 2 below disclose turbochargers that fix a compressor impeller into which a turbine shaft is inserted with a fastener (nut). When assembling such a turbocharger, the axial force acting on the turbine shaft is a predetermined value so that slippage between the compressor impeller and the turbine shaft does not occur and mechanical damage is not caused to the turbine shaft. It is necessary to tighten the fastener so that Conventionally, the axial force is evaluated by measuring torque acting on a fastener (nut) with a torque wrench or the like.
JP 2006-9634 A JP-A-5-79346

However, the conventional method for evaluating the axial force has a serious problem in terms of accuracy. That is, the relationship between the torque and the axial force fluctuates due to a difference in surface properties such as a compressor impeller or a fastener (nut), individual differences of workers performing a tightening operation, and the like, and 30 in an extreme case. An error as large as a percentage can occur.
In order to eliminate such errors, it is conceivable to evaluate the axial force with a dedicated measuring device (axial force measuring device), but at present, the axial force required for assembling the turbine shaft of the turbocharger is considered. An axial force measuring instrument having a performance that satisfies the setting accuracy has not been put into practical use.

The present invention has been made in view of the above-described circumstances, and has the following objects.
(1) When fixing a compressor impeller to a turbine shaft using a fastener, an axial force acting on the turbine shaft is measured with high accuracy.
(2) Assemble the turbocharger to satisfy the desired performance.
(3) Reduce individual differences in turbocharger performance.

The present invention employs the following means in order to solve the above problems.
That is, the present invention, as a first solution means for measuring the axial force of the turbine shaft, by inserting an insertion portion formed on one end side of the turbine shaft and having a threaded portion at the tip into the compressor impeller, A method for measuring an axial force acting on the turbine shaft when the compressor impeller is pressed and fixed to a receiving surface formed between one end and the other end of the turbine shaft by a fastening nut screwed to the screw portion. The insertion portion is inserted into the compressor impeller with a strain gauge provided in advance on the surface of the insertion portion to press and fix the compressor impeller, and the axial force is determined based on the strain amount indicated by the strain gauge. The measure is used.

  Further, as a second solving means relating to the turbine shaft axial force measuring method, in the first solving means relating to the turbine shaft axial force measuring method, the turbine shaft axis is sandwiched between the surfaces of the insertion portion. A means is adopted in which strain gauges are provided at symmetrical positions, and the axial force is measured based on the strain amount of each strain gauge.

  Further, as a third solving means relating to the axial force measuring method of the turbine shaft, in the first or second solving means relating to the axial force measuring method of the turbine shaft, a strain gauge lead wire is arranged in the turbine shaft. A means is adopted in which a through hole is formed at the end and a strain amount is obtained from a lead wire drawn out from the through hole.

  In addition, as a first solving means related to the supercharger, a compressor impeller inserted through a casing and an insertion portion formed on one end side of the turbine shaft and having a threaded portion at the tip thereof is connected to one end of the turbine shaft and the other. A rotating portion that is pressed and fixed by a fastening nut screwed to the screw portion on a receiving surface formed between the end and a turbine impeller fixed to the other end of the turbine shaft; and The turbocharger includes a bearing portion that is rotatably supported with respect to the casing, and the turbine shaft employs a means in which a strain gauge is provided on a surface of the insertion portion.

  Further, as a second solving means relating to the supercharger, in the first solving means relating to the supercharger, the strain gauge is provided at a symmetrical position across the axis of the turbine shaft. Adopt the means.

  Further, as a third solution means related to the supercharger, in the first or second solution means related to the supercharger, the turbine shaft is for the lead wire of the strain gauge to be pulled out to the shaft end. A means is adopted in which a through hole is provided, and the lead wire of the strain gauge is inserted into the through hole.

  Further, as a fourth solving means related to the supercharger, in any one of the first to third solving means related to the supercharger, the strain gauge is formed in the insertion portion of the turbine shaft. A means of being provided in the chamfered portion is adopted.

  Further, as a fifth solving means relating to the supercharger, in the fourth solving means relating to the supercharger, the chamfered portion corresponds to a maximum diameter of the compressor impeller in the axial direction of the turbine shaft. Or the means of being provided in the vicinity is employ | adopted.

  According to the present invention, the compressor impeller is inserted in a state in which a strain gauge is provided in advance on the surface of the insertion portion provided in the turbine shaft, the compressor impeller is pressed and fixed, and the axial force is based on the strain amount indicated by the strain gauge. Therefore, the axial force is indirectly measured based on the amount of strain detected by the strain gauge. According to the present invention, since the distortion amount of the insertion portion is a physical quantity that accurately reflects the axial force, it is possible to measure the axial force with high accuracy, and as a result, a turbocharger with desired performance is assembled. It is possible to reduce the variation in performance when a large number of turbochargers are assembled.

  Further, since the axial force is measured based on the strain amount of a strain gauge provided at a symmetrical position across the axis of the turbine shaft, even if the turbine shaft is bent and deformed when the compressor impeller is fixed with a fastener, The axial force is measured from the average value of the detected strain amount. As a result, the strain component in the bending direction is canceled out, and an accurate axial force can be measured only from the strain component in the axial direction.

  In addition, a through hole is provided in the turbine shaft, and a strain amount is obtained from a lead wire drawn out from the through hole. Therefore, a transmitter (telemeter) for wirelessly transmitting the strain amount detected by the strain gauge is provided. There is no need. This makes it possible to measure the axial force with high accuracy with an inexpensive and simple configuration.

  Further, since the chamfered portion is provided in the insertion portion of the turbine shaft and the strain gauge attached to the chamfered portion is provided, the compressor impeller can be inserted with the strain gauge provided in the insertion portion. As a result, it is possible to detect the amount of distortion of the insertion portion generated by tightening the fastener, and it is possible to measure the axial force of the turbine shaft from the detected amount of distortion.

  Further, since the chamfered portion is provided at or near the position corresponding to the maximum diameter of the compressor impeller in the axial direction, the bending load is distributed to the compressor impeller and the chamfered portion is difficult to bend and deform. As a result, it is possible to measure an accurate axial force without detecting an amount of distortion due to a load other than the axial force acting in the axial direction.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view showing a configuration of a supercharger A according to the present embodiment, FIG. 2 is a partial cross-sectional view of a rotating unit 1 in the supercharger A, and FIG. 3 (a) is an IIIa arrow view in FIG. 2, FIG. 3 (b) is an enlarged view of the main part IIIb in FIG. 2, and FIG. It is a IIIc arrow directional view in FIG.3 (b). Here, in the figure, the central axis (axial center) of the rotating unit 1 is P.

  As shown in FIG. 1, the supercharger A is one in which a rotating part 1 is rotatably mounted on a casing 20 via a bearing part 10.

  As shown in FIGS. 1 and 2, the rotating unit 1 includes a turbine shaft 2, a turbine impeller 3, a compressor impeller 4, a fastening nut 5, a pair of strain gauges 6 and 7, a thrust bush 8 and an oil drain 9. ing.

  The turbine shaft 2 is arranged on the central axis P of the rotating portion 1 and has a large-diameter supported portion 2a, a compressor impeller 4, a thrust bush 8 and oil that are rotatably supported by the bearing portion 10. A small-diameter insertion portion 2b to be inserted into the cut 9 is provided. A receiving surface 2c perpendicular to the central axis P is formed at the boundary between the supported portion 2a and the insertion portion 2b.

  On the outer peripheral surface of the insertion portion 2b, a screw portion 2d is formed at the other end (see FIG. 2), and two chamfered portions 2e are formed at a position corresponding to the maximum diameter of the compressor impeller 4 in the direction of the central axis P. (See FIGS. 3A and 3B). These two chamfered portions 2e are formed so as to be symmetric with respect to the axis (center axis P) and so that the respective planes are parallel to each other.

  Further, as shown in FIGS. 2 and 3, a through hole 2g that penetrates the two chamfered portions 2e and the shaft end 2f is formed in the insertion portion 2b. This through-hole 2g is drilled by electric discharge machining, and is branched from the chamfered portion 2e and the pore 2g1 drilled from the center of the shaft end 2f to the branch point Q at the substantially center of the insertion portion 2b along the central axis P. It consists of two pores 2g2 drilled to point Q.

As shown in FIG. 3B, the pore 2g2 is formed in an inclined state with respect to the central axis P so as to be directed to the central axis P toward the axial end 2f side. Each angle between 2g2 and the pore 2g1 is an obtuse angle.
The through hole 2g is about 9 mm of the outer diameter of the insertion portion 2d, whereas the diameter of the through hole 2g is about 1 mm. The lead wires 6a and 7a can be reliably inserted.

  Returning to FIG. 2, the turbine impeller 3 includes a plurality of long blades and short blades formed in a radial pattern, and is fixed to one end of the turbine shaft 2. Specifically, the turbine shaft 2 is fixed to the end surface on the supported portion 2a side by welding.

  Like the turbine impeller 3, the compressor impeller 4 is provided with a plurality of long blades and short blades alternately, and the insertion portion 2b is inserted into the insertion hole 4a and fastened through the thrust bush 8 and the oil drain 9 The nut 5 is pressed and fixed.

  The fastening nut 5 is screwed to the screw portion 2d, and receives the compressor impeller 4, the thrust bush 8, and the oil drain 9 against the receiving surface 2c to fix them to the turbine shaft 2 (insertion portion 2b). . The fastening nut 5 is tightened so that an axial force value F2 is generated in the insertion portion 2b. The axial force value F2 is set to an axial force value at which the compressor impeller 4 does not slip with respect to the turbine shaft 2 and the turbine shaft 2 is not likely to be damaged.

The strain gauges 6 and 7 are provided in the chamfered portion 2e on the turbine shaft 2 (insertion portion 2b), and the lead wires 6a and 7a are inserted through the through holes 2g and drawn to the shaft end 2f.
As shown in FIGS. 3A and 3B, the strain gauges 6 and 7 are symmetrical with respect to the center axis P at a position corresponding to the maximum diameter of the compressor impeller 4 in the axial direction of the center axis P. In addition, as shown in FIG. 3C, it is attached so that distortion in the direction of the central axis P can be detected.

  Each of the lead wires 6a and 7a has one end inserted obliquely from the opening on the chamfered portion 2e side to the branch point Q along the pore 2g2 and further to the shaft end 2f. At this time, as described above, since the respective angles between the two pores 2g2 and 2g1 are obtuse, the lead wires 6a and 7a are obstructed by the corners in the middle of the through hole 2g. It can be made to enter smoothly without any problems. One end of each of the lead wires 6a and 7a drawn out from the through hole 2g is connected to a strain axial force transducer (not shown).

  The thrust bush 8 transmits a load in the axial direction of the rotating portion 1 to a thrust bearing 15 described later, and constitutes the rotating portion 1 and the bearing portion 10. The thrust bush 8 is a substantially cylindrical member having a flange, and one end face on the flange side is in contact with the receiving surface 2c and the other end face is in contact with the oil drain 9, and like the compressor impeller 4. The fastening nut 5 is pressed and fixed to the turbine shaft 2.

  The oil drain 9 is a member that seals the oil O supplied to a bearing casing 21 described later together with the seal plate 23. The oil drain 9 has a substantially cylindrical shape with a concave portion formed on the outer peripheral surface. One end surface is in contact with the thrust bush 8 and the other end surface is in contact with the compressor impeller 4. Is pressed and fixed to the turbine shaft 2.

  In the present embodiment, the bearing portion 10 has a full float type floating bush bearing structure, and includes a thrust bush 8, a bearing casing 21, a pair of floating metals 12A and 12B, a thrust bearing 15, and a pair of retaining rings 13. , Bearing spacer 14 and oil O. The bearing casing 21 constitutes the bearing portion 10 and the casing 20.

  The bearing casing 21 is formed with a shaft insertion hole 21a through which the turbine shaft 2 is inserted and a flow path 21b of oil O supplied from the vehicle. The flow path 21b is configured so that the turbine casing 22 side is mainly cooled after the oil O is supplied to the floating metals 12A and 12B and the thrust bush 8, and is finally discharged to the outside. Has been.

  The floating metals 12A and 12B are cylindrical members having a plurality of through holes on the peripheral surface, and are provided between two points spaced apart from each other by the turbine shaft 2 (supported portion 2a) and a bearing casing 21 described later. It has been.

The retaining ring 13 has a C-shaped cross section and is locked to a circumferential groove provided in a peripheral wall forming the shaft insertion hole 21a to restrict the movement of the floating metal 12A in the axial direction. is doing.
The bearing spacer 14 is a ring-shaped member, and is engaged with the peripheral wall of the shaft insertion hole 21a to restrict the axial movement of the floating metal 12B together with the thrust bush 8.

  The thrust bearing 15 is a hollow disk-shaped member, and the turbine shaft 2 is inserted through the thrust bush 8. The flange portion of the thrust bush 8 is fixed to the bearing casing 21 so as to be sandwiched between the bearing casing 21 and the floating metal 12B. With such a configuration, the thrust bearing 15 receives a load in the thrust direction of the turbine shaft 2 from the thrust bush 8.

  In such a bearing 10, oil O is continuously supplied during operation of the supercharger A, and an oil film is formed and held on the inner and outer peripheral surfaces of the floating metals 12 </ b> A and 12 </ b> B. The turbine shaft 2 rotates through the oil film inside the floating metals 12A and 12B, and the floating metals 12A and 12B rotate through the oil film as the turbine shaft 2 rotates. The rotational speed of the floating metals 12A and 12B is, for example, about several tens of percent of the rotational speed of the turbine shaft 2. With such a configuration, the turbine shaft 2 can be rotatably supported even when the turbine shaft 2 rotates at a high rotational speed.

  The casing 20 is configured by joining a turbine casing 22 to one end of a bearing casing 21, a seal plate 23 to the other end of the bearing casing 21, and a compressor casing 24 to the seal plate 23.

  The turbine casing 22 includes an accommodating portion 22a that accommodates the turbine impeller 3 and a scroll portion 22b that is formed to wrap around the accommodating portion 22a, and a flow path for exhaust gas supplied from the vehicle by being joined to the bearing casing 21. Is forming.

  The seal plate 23 is a substantially disk-shaped member, and the turbine shaft 2 is inserted through the oil drain 9 into a through-hole formed at a substantially center. The through hole is provided with a ring-shaped seal ring 23a, and the seal ring 23a is engaged with a recess provided on the outer peripheral surface of the oil drain 9 described above, whereby the bearing casing 21 is engaged. The oil O supplied to is prevented from leaking into the compressor casing.

  The compressor casing 24 includes an accommodating portion 24a that accommodates the compressor impeller 4 and a scroll portion 24b that is formed to wrap around the accommodating portion 24a. The compressor casing 24 joins the bearing casing 21 to form a flow path of air supplied to the vehicle. is doing.

Next, the assembly procedure of the supercharger A having the above configuration will be described.
When the supercharger A is assembled, the floating metals 12A and 12B are provided on the bearing casing 21 to which the turbine casing 22, the seal plate 23, the compressor casing 24, and the like are not attached. Then, the turbine shaft 2 to which the turbine impeller 3 is fixed is inserted into the bearing casing 21 from the turbine casing 22 side to the compressor casing 24 side.

  Next, after the thrust bush 8 is inserted into the insertion portion 2 b of the turbine shaft 2, the thrust bearing 15 is fixed to the inner end surface of the bearing casing 21, and the insertion portion 2 b is inserted into the oil drain 9.

Next, the seal plate 23 is fixed to the bearing casing 21, and the insertion portion 2 b is inserted into the compressor impeller 4. At this time, since the strain gauges 6 and 7 are affixed to the chamfered portion 2e and do not protrude outward from the outer peripheral surface of the insertion portion 2b, the strain gauges 6 and 7 are formed on the formation surface of the insertion hole 4a in the compressor impeller 4. There will be no interference. Then, the fastening nut 5 is screwed onto the screw portion 2d, and the fastening nut 5 is tightened with a spanner while the turbine shaft 2 is fixed.
Further, after the fastening nut 5 is screwed to the screw portion 2d, the lead wires 6a and 7a drawn from the shaft end 2f are connected to a strain axial force transducer (not shown).

  When the end surface of the fastening nut 5 comes into contact with the compressor impeller 4 and the spanner is further tightened, the compressor impeller 4, the oil drain 9 and the thrust bush 8 are pressed against the fastening nut 5 and the receiving surface 2c, and the insertion portion 2b is pivoted. By being pulled in the direction, axial strain ε and axial force F (tensile stress) are generated in the insertion portion 2b.

  At this time, the turbine shaft 2 is fixed, and bending deformation occurs in the turbine shaft 2 as a whole due to the force applied to the spanner. Here, in the chamfered portion 2e, the bending load is distributed to the compressor impeller 4 and the amount of bending deformation is minute.

The strain gauges 6 and 7 detect the strain ε of the core chamfer 2e generated at this time, and transmit the detected values ε _a and ε _b to the strain axial force transducer connected to the lead wires 6a and 7a.

  A strain axial force transducer (not shown) connected to the lead wires 6a and 7a stores in advance data indicating the relationship between the strain ε and the axial force F indicated by this characteristic curve. 7, when each detected value of strain ε is input, an average value of the two detected values is calculated, and a measured value of axial force F corresponding to this value is provided in the strain axial force converter. As shown on the monitor.

FIG. 4 shows a characteristic curve showing the relationship between the axial force F generated in the insertion portion 2b and the strain ε.
The characteristic curve diagram shown in FIG. 4 is obtained by preparing a part equivalent to the turbine shaft 2 in advance and conducting a tensile test on the insertion portion 2b to obtain the relationship between the axial force F (tensile load) and the strain ε. .

The strain axial force converter calculates an average value of the detected values ε _a and ε _b transmitted from the lead wires 6a and 7a, and based on the calculated average value based on the characteristic curve diagram shown in FIG. In terms of force F, the converted axial force value F1 of the axial force F is displayed on the monitor.

Then, until the strain ε reaches the detected value ε2, that is, after tightening the fastening nut 5 to the prescribed axial force value F2, the lead wires 6a and 7a drawn outward from the shaft end 2f are cut, and the turbine casing is cut. 22 is fixed to the bearing casing 21, and the compressor casing 24 is fixed to the seal plate 23.
The supercharger A assembled in this way is attached to the vehicle and is stably operated.

  As described above, according to the present invention, the compressor impeller 4 is inserted and fixed in a state where the strain gauges 6 and 7 are provided in advance on the surface of the insertion portion 2b provided in the turbine shaft 2, and the strain gauge 6, Since the axial force F is measured based on the strain amount ε detected by 7, the axial force F is indirectly measured based on the strain amount ε. According to the present invention as described above, since the distortion amount ε of the insertion portion is a physical quantity that accurately reflects the axial force, the axial force F can be measured with high accuracy.

  Therefore, it is not necessary to tighten the fastening nut 5 with an axial force value lower than the prescribed axial force value F2 in consideration of an error, and the compressor impeller 4 can be completely prevented from slipping. Further, in consideration of the error of the axial force F, it is not necessary to use a material having high strength for the turbine shaft 2 or to increase the size of the turbine shaft 2, and the turbine shaft 2 can be used optimally. It becomes possible. Furthermore, individual differences in performance of the supercharger A can be reduced.

  Further, since the axial force F is measured based on the strain amount ε detected by the strain gauges 6 and 7 provided at symmetrical positions with respect to the central axis P (axial center) of the turbine shaft 2, the compressor impeller 4 is fastened with a fastening nut. The axial force F is measured from the average value of the two strains ε even if bending deformation occurs in the turbine shaft 2 when fixing at 5. Thereby, the distortion component in the bending direction is canceled out, and the accurate axial force F can be measured only from the distortion component in the central axis P direction.

Further, since the chamfered portion 2e is provided in the insertion portion 2b of the turbine shaft 2 and the strain gauges 6 and 7 attached to the chamfered portion 2e are provided, the compressor is provided with the strain gauges 6 and 7 provided in the insertion portion 2b. The impeller 4 can be inserted smoothly.
Further, the strain gauges 6 and 7 are covered and reliably held by the inner surface of the compressor impeller 4. That is, it is possible to prevent the strain gauges 6 and 7 from falling off when the rotating unit 1 is rotated.

Further, since the two chamfered portions 2e are provided at symmetrical positions with the central axis P (axial center) of the turbine shaft 2 in between, the distance between them is farthest from the outer peripheral surface of the central axis P. Thereby, it is possible to minimize the influence of one chamfered portion 2e on the other chamfered portion 2e. That is, the distribution of the torsional stress is made axisymmetric so that the torsional stress is prevented from concentrating on a part, and the decrease in the sectional secondary pole moment is minimized compared with the case where the two chamfered portions 2e are not provided. Can be.
Furthermore, it is possible to minimize the deterioration of the rotational balance around the central axis P of the portion provided with the chamfered portion 2e.

  Further, since the chamfered portion 2e, the through-hole 2g (pores 2g1, 2g2), and the strain gauges 6, 7 are provided symmetrically around the central axis P, it is easy to balance the rotation of the rotating portion 1. can do.

  Further, since a through hole 2g is provided in the turbine shaft 2 and the strain amount ε is acquired from the lead wires 6a and 7a drawn from the through hole 2g, the strain amount ε detected by the strain gauges 6 and 7 is wirelessly transmitted. There is no need to provide a transmitter (telemeter). Thereby, it is possible to measure the axial force F with high accuracy with an inexpensive and simple configuration.

  Further, the chamfered portion 2e is provided at a position corresponding to the maximum diameter of the compressor impeller 4 in the axial direction of the turbine shaft 2, and the bending load is distributed to the compressor impeller 4 so that the chamfered portion 2e is hardly bent and deformed. . Accordingly, it is possible to measure the accurate axial force F without detecting the strain amount ε due to the load other than the axial force F acting in the axial direction.

In addition, this invention is not limited to the said embodiment, For example, the following modifications can be considered.
(1) In the above embodiment, the chamfered portion 2e is formed at a position corresponding to the maximum diameter of the compressor impeller 4 in the axial direction of the turbine shaft 2 (so as to face a position corresponding to the position of the air inlet). This is because the distortion amount ε is detected very accurately while avoiding the influence of the bending of the turbine shaft 2, and an accurate detection value can be obtained even in the vicinity of the position corresponding to the maximum diameter of the compressor impeller 4. In addition, good detection values can be obtained at other positions.

(2) In the above embodiment, two strain gauges are provided. However, the axial force F can be obtained by detecting the strain amount ε from one strain gauge. Further, two or more strain gauges may be provided, and an average value may be calculated from the strain amount ε detected by each strain gauge, thereby obtaining the axial force F.
(3) In the above embodiment, the lead wires 6a and 7a are cut after reaching the prescribed axial force. However, the lead wires 6a and 7a are accommodated in the fastening nut 5 using an accommodating portion (for example, a cap nut). During the maintenance, the fastening nut 5 may be connected again with a predetermined axial force F by reconnecting to the strain axial force transducer.

In one Embodiment of this invention, it is a figure which shows the schematic block diagram of the supercharger A. FIG. In one Embodiment of this invention, it is a partial cross section figure of the rotation part 1. FIG. In one Embodiment of this invention, it is a principal part enlarged view of the rotation part 1, Comprising: Fig.3 (a) is a IIIa arrow line view in FIG. 2, FIG.3 (b) is a principal part in FIG. FIG. 3C is an enlarged view of IIIb, and FIG. 3C is a view taken in the direction of arrow IIIc in FIG. In one Embodiment of this invention, the characteristic curve which shows the relationship between the axial force F which generate | occur | produces in the insertion part 2b, and distortion | strain (epsilon) is shown.

Explanation of symbols

2 ... Turbine shaft 2b ... Insertion part 2e ... Chamfer 2f ... End face 2g ... Through hole 3 ... Turbine impeller 4 ... Compressor impellers 6, 7 ... Strain gauges 6a, 7a ... Lead wire 10 ... Bearing part 20 ... Casing A ... Supercharging Machine F ... Axial force ε ... Strain amount

Claims (8)

An insertion portion formed at one end of the turbine shaft and having a threaded portion at the tip is inserted into a compressor impeller, and the compressor impeller is placed on a receiving surface formed between one end and the other end of the turbine shaft. A method of measuring an axial force acting on the turbine shaft when being pressed and fixed with a fastening nut that is screwed onto a screw part,
With the strain gauge provided in advance on the surface of the insertion portion, the insertion portion is inserted into the compressor impeller to press and fix the compressor impeller, and the axial force is measured based on the strain amount indicated by the strain gauge. A method for measuring the axial force of a turbine shaft, characterized in that   2. The strain gauge according to claim 1, wherein strain gauges are provided at symmetrical positions on the surface of the insertion portion with the axis of the turbine shaft interposed therebetween, and the axial force is measured based on a strain amount of each strain gauge. A method for measuring the axial force of a turbine shaft.   The turbine according to claim 1 or 2, wherein a through hole for pulling out a lead wire of a strain gauge to the shaft end is provided in the turbine shaft, and the amount of strain is obtained from the lead wire drawn out from the through hole. Axial force measurement method for shafts. A compressor impeller inserted through a casing and an insertion portion formed at one end of the turbine shaft and having a threaded portion at the tip thereof is formed on the receiving surface formed between one end and the other end of the turbine shaft. And a rotating part having a turbine impeller fixed to the other end of the turbine shaft and a bearing part for rotatably supporting the rotating part with respect to the casing. A turbocharger comprising:
The turboshaft is provided with a strain gauge on the surface of the insertion portion.   The supercharger according to claim 4, wherein the strain gauge is provided at a symmetrical position across the axis of the turbine shaft.   The turbine shaft is provided with a through-hole for pulling out the lead wire of the strain gauge to the shaft end, and the lead wire of the strain gauge is inserted into the through-hole. 5. The turbocharger according to 5.   The supercharger according to any one of 4 to 6, wherein the strain gauge is provided in a chamfered portion formed in an insertion portion of the turbine shaft.   The supercharger according to claim 7, wherein the chamfered portion is provided at or near a position corresponding to the maximum diameter of the compressor impeller in the axial direction of the turbine shaft.

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