JPH0435536Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a variable displacement turbocharger equipped with variable nozzle vanes, and particularly relates to a nozzle vane support structure when the nozzle vanes are made of ceramic.

[Prior Art] Various structures of turbochargers equipped with variable nozzle vanes have been known in the past, and are designed to prevent galling between the nozzle vanes and the inner wall surfaces of the gas passages at both ends due to thermal expansion of the nozzle vanes. The structure is known, for example, from Japanese Utility Model Application Publication No. 19602/1983.

Furthermore, a technique in which the nozzle vane is made of ceramic having excellent heat resistance and a small coefficient of thermal expansion is also known. By constructing the nozzle vane from ceramic having a small coefficient of thermal expansion, it is possible to reduce the gap between the wall surface of the annular gas passage and the blade end surface of the nozzle vane. Therefore, gas leakage from the gap is suppressed to a small level, and the efficiency of the turbocharger can be improved.

FIG. 4 shows an example of a nozzle vane support structure in a conventional variable displacement turbocharger. In FIG. 4, 1 indicates a nozzle vane, and the nozzle vane 1 is entirely made of ceramic. Shaft 1a of nozzle vane 1
is rotatably supported by a bush 3 press-fitted into the housing 2, and a rotation lever 4 for rotating the nozzle vane 1 is attached to the end of the shaft 1a.

FIG. 5 shows another example of a nozzle vane support structure in a conventional variable displacement turbocharger. The nozzle vane 5 is rotatably supported by a bush 3 that is press-fitted into the housing 2 as in FIG. 4. Unlike the integral structure shown in FIG. 4, the nozzle vane 5 is constructed by mechanically bonding a ceramic member and a metal member.

In other words, the nozzle vane portion 5 becomes extremely hot.
The shaft 5b, which is subject to less severe thermal conditions than the nozzle vane portion 5a, is made of a metal member. and,
The coupling structure between the nozzle vane portion 5a and the shaft 5b is a shrink-fitting structure 6.

[Problems to be solved by the invention] However, the support structure of the nozzle vane is
If the structures shown in the figures and FIG. 5 are used, the following problems occur. In other words, since ceramic is more fragile than metal materials, if the nozzle vane portion and the shaft are integrally formed as shown in FIG. 4, a problem arises in that the shaft is easily damaged by the fastening force when assembling the nozzle.

In addition, in a structure in which only the shaft is made of a metal member and connected by shrink fitting as shown in Fig. 5,
When the temperature of the joint exceeds the shrink-fitting temperature, the amount of thermal expansion of the metal shaft at the joint becomes greater than that of the nozzle vane made of ceramic, so the shrink-fit becomes ineffective and rotational driving force is transmitted to the nozzle vane. The problem arises that it is no longer possible.

Also, as can be said for both the structures shown in FIGS. 4 and 5, there is a gap between the nozzle vane and the member that supports the nozzle vane (for example, a bush), so that the nozzle vane can rotate. There is a problem in that the nozzle vane tilts downward by the gap due to its own weight, and a portion of the blade tip of the nozzle vane comes into contact with the wall surface of the gas passage, resulting in galling.

The present invention focuses on the above-mentioned problems, and in a turbocharger in which the nozzle vane is made of ceramic, it is possible to prevent the nozzle vane shaft from being damaged when the nozzle vane is assembled, and to ensure that rotational driving force is transmitted to the nozzle vane even under high temperatures. Moreover, it is an object of the present invention to provide a nozzle vane support structure for a variable displacement turbocharger that can prevent the nozzle vane from tilting due to a gap around the shaft of the nozzle vane.

[Means for Solving the Problems] A nozzle vane support structure for a variable displacement turbocharger according to the present invention in accordance with this objective includes a nozzle vane disposed in an annular gas passage formed between a swirl chamber and a turbine wheel, and a nozzle vane supporting structure for a variable displacement turbocharger of the present invention. In the variable displacement turbocharger, the shaft of the nozzle vane is rotatably supported on the housing side, and the nozzle vane is made of ceramic, and the shaft of the nozzle vane is inserted into a hollow metal shaft rotatably supported by the housing. A shaft of the nozzle vane protruding from the metal hollow shaft is provided with an engaging portion that engages with each other and transmits rotational driving force from the metal hollow shaft to the nozzle vane, at the base of the shaft and one end of the metal hollow shaft. A biasing means is provided at the end of the nozzle vane to constantly bring the axial end surface of the engaging portion of the nozzle vane into contact with the axial end surface of the engaging portion of the hollow metal shaft.

[Operation] In the variable displacement turbocharger nozzle vane support structure configured as described above, rotational driving force is transmitted to the nozzle vane via the engagement portion by rotating the metal hollow shaft. In other words, when assembling the nozzle vane, the rotating lever is not attached directly to the shaft of the nozzle vane made of ceramic, but to the metal hollow shaft, so there is no chance of the nozzle vane shaft being damaged during assembly as in the conventional method. is prevented. Note that since the engaging portion is formed at the base of the shaft of the nozzle vane, no large torsional force is applied to the shaft itself.

In addition, since the rotational driving force from the metal hollow shaft is applied via the engaging part that has the same function as a spline, the bonding force between the two is not affected by temperature as in shrink fitting, so it can be used even under high temperatures. The rotational driving force from the metal hollow shaft is reliably transmitted to the nozzle vane.

Furthermore, the axial end surface of the engaging portion of the nozzle vane is constantly brought into contact with the end surface of the engaging portion of the metal hollow shaft by the biasing means, so that the rotation center axis of the nozzle vane and the rotation center of the metal hollow shaft are brought into contact with each other. The axis remains parallel. Therefore, the inclination of the nozzle vane is corrected and galling is prevented.

[Example] Below, preferred examples of the nozzle vane support structure of a variable displacement turbocharger according to the present invention are as follows.
This will be explained with reference to the drawings.

1 to 3 show a nozzle vane support structure for a variable displacement turbocharger according to an embodiment of the present invention. In Figures 1 and 3,
11 indicates a turbine housing, and 12 indicates a center housing. The turbine housing 11 and the center housing 12 are fastened together at their outer peripheries by, for example, a V-band. A spiral chamber 13 is formed on the inner outer peripheral side of the turbine housing 11, and an annular gas passage 15 is formed from the spiral chamber 13 to the turbine wheel 14 by the inner wall of the turbine housing 11 and the inner wall of the center housing 12. ing. This annular gas passage 1
5, a plurality of nozzle vanes 16 for adjusting the inflow speed of exhaust gas are disposed in an appropriate number in the circumferential direction. The nozzle vane 16 is made of ceramic, and has a nozzle vane portion 16a and a shaft 1.
6b is integrally formed.

The center housing 12 includes a nozzle vane 16.
A bearing 17 supporting the is press-fitted. Bearing 17
is the center housing 1 from the annular gas passage 15 side.
2, and one end thereof is exposed to the atmosphere. The bearing 17 is formed so that the diameter on the annular gas passage 15 side is larger than the diameter on the side exposed to the atmosphere,
Its shaft end is flush with the wall surface of the annular gas passage 15. A metal hollow shaft 18 having a large diameter at one end is rotatably inserted through the annular gas passage 15 side of the bearing 17 .

One end of the metal hollow shaft 18 is located inside the bearing 17 from the end surface of the bearing 17 on the annular gas passage 15 side, and the other end protrudes from the end surface of the bearing 17 on the side exposed to the atmosphere. A concave engaging portion 18a that can be engaged with the nozzle vane 16 is provided at the end of the metal hollow shaft 18 on the annular gas passage 15 side. A rotating lever 20 is attached to the end of the metal hollow shaft 18 that is exposed to the atmosphere. The rotating lever 20 is a fixed member 2
1 is pressed against the stepped portion of the metal hollow shaft 18 and fixed.

The shaft 16b of the nozzle vane 16 described above is inserted into the hollow portion of the metal hollow shaft 18. The end of the shaft 16b protrudes from the end surface of the metal hollow shaft 18 on the side exposed to the atmosphere. An engaging portion 16c that can engage with an engaging portion 18a at the end of the metal hollow shaft 18 is formed at the base of the shaft 16b. Nozzle vane 16
The engaging portion 16c has a rectangular cross-sectional shape as shown in FIG. That is, the shape of the engaging portion 16c of the nozzle vane 16 is formed to be similar to the engaging portion 18a of the metal hollow shaft 18, and is fitted into the engaging portion 18a with almost no looseness.

The axial end surface 18b of the engaging portion 18a of the metal hollow shaft 18 is perpendicular to the rotation center axis of the metal hollow shaft 18. An axial end surface 16d of the engaging portion 16b of the nozzle vane 16 is perpendicular to the rotation center axis of the nozzle vane 16.

A retaining ring 23 is attached to the end of the shaft 16b of the nozzle vane 16 that protrudes from the end surface 18c of the metal hollow shaft 18 exposed to the atmosphere. A compression coil spring 22 is interposed between the retaining ring 23 and the end surface 18c of the metal hollow shaft 18 as a biasing means. This results in
End face 1 of engaging portion 18a of metal hollow shaft 18
8b and the end surface 1 of the engaging portion 16c of the nozzle vane 16
6d are always in contact with each other.

Next, the operation of the nozzle vane support structure of the variable displacement turbocharger described above will be explained.

The rotary lever 20 is rotated by a link mechanism (not shown).
When driven, the metal hollow shaft 18 rotates within the bearing 17, and the force is applied to the engaging portions 18a, 16c.
is transmitted to the nozzle vane 16 via. That is, since the engaging portion 18a of the metal hollow shaft 18 and the engaging portion 16c of the nozzle vane 16 are fitted together with almost no play, the metal hollow shaft 1
The rotational driving force from 8 is reliably transmitted to nozzle vane 16. In other words, since the two are engaged with each other, there is no possibility of slippage, and the rotational driving force is prevented from being transmitted to the nozzle vane 16 due to the influence of thermal expansion.

Furthermore, because the compression coil spring 22 causes the end surface 16d of the engagement portion 16c of the nozzle vane 16 to be in close contact with the end surface 18b of the engagement portion of the metal hollow shaft 18, the rotation center axis of the metal hollow shaft 18 and the nozzle vane 16 The nozzle vane 16 is maintained parallel to the center axis of rotation, and the nozzle vane 16 is prevented from tilting downward. That is, the posture of the nozzle vane 16 is constantly corrected by the compression coil spring, and a portion of the blade end surface of the nozzle vane 16 is prevented from contacting the inner wall of the annular gas passage 15, thereby eliminating galling.

As a result, the blade end surface 16e of the nozzle vane 16
is substantially parallel to the wall surface 15a forming the annular gas passage 15, and the gap between the blade end surface 16e of the nozzle vane 16 and the wall surface 15a is made uniform. This is very convenient for managing the gap between the nozzle vane 16 and the annular gas passage 15.

In addition, in this embodiment, each engaging portion 16c,
Although the cross-sectional shape of 18a is square, it is not limited to square and may have any shape as long as the rotational driving force is reliably transmitted from metal hollow shaft 18 to nozzle vane 16.

[Effects of the Invention] As explained above, when the nozzle vane support structure of the variable displacement turbocharger of the present invention is used, the following effects can be obtained.

(a) A mechanism that inserts the shaft of the nozzle vane into the hollow metal shaft and engages the base of the shaft of the nozzle vane and one end of the hollow metal shaft to transmit rotational driving force from the hollow metal shaft to the nozzle vane. Since the joint is provided, there is no need to attach a rotating lever etc. to the nozzle vane shaft, which prevents damage to the nozzle vane shaft when assembling the nozzle vane, and also prevents the metal hollow shaft from being damaged even under high temperatures. Rotational driving force can be reliably transmitted from the nozzle vane to the nozzle vane.

(b) Furthermore, since the engaging portion of the nozzle vane is provided at the base of the shaft, no large rotational driving force is applied to the shaft itself, and breakage at the shaft portion can be reliably prevented.

(c) Since the end of the shaft of the nozzle vane protruding from the hollow metal shaft is provided with a biasing means for constantly abutting the end surface in the axial direction of the engagement portion between the hollow metal shaft and the nozzle vane,
It becomes possible to make the rotation center axis of the nozzle vane parallel to the rotation center axis of the metal hollow shaft, and it is possible to maintain a uniform gap between the blade end surface of the nozzle vane and the wall surface of the annular gas passage.

As a result, it is possible to prevent galling due to contact between the blade end surface of the nozzle vane and the wall surface of the annular gas passage, and it is also possible to easily manage the gap and significantly reduce the gap.
Turbine efficiency can be significantly improved.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a nozzle vane support structure of a variable displacement turbocharger according to an embodiment of the present invention;
Fig. 2 is a sectional view taken along the - line in Fig. 1, Fig. 3 is an overall sectional view of a variable displacement turbocharger to which the nozzle vane support structure of Fig. 1 is applied, and Fig. 4 is a cross-sectional view of a nozzle vane in a conventional variable displacement turbocharger. FIG. 5 is a sectional view showing an example of a support structure, and FIG. 5 is a sectional view showing another example of a nozzle vane support structure in a conventional variable displacement turbocharger. 11... Turbine housing, 12... Center housing, 15... Annular gas passage, 16... Nozzle vane, 16b... Shaft, 16c, 18
a... Engaging portion, 16d, 18b... Axial end surface of the engaging portion, 18... Metal hollow shaft, 22...
...Compression coil spring as a biasing means.

Claims (1)

[Scope of utility model registration request] A variable displacement turbocharger, in which a nozzle vane is disposed in an annular gas passage formed between a swirl chamber and a turbine wheel, and a shaft of the nozzle vane is rotatably supported on a housing side,
The nozzle vane is made of ceramic, and the shaft of the nozzle vane is inserted into a metal hollow shaft rotatably supported by the housing,
An engaging portion is provided at the base of the shaft of the nozzle vane and one end of the metal hollow shaft to engage with each other and transmit rotational driving force from the metal hollow shaft to the nozzle vane, and protrudes from the metal hollow shaft. A variable capacity variable capacity characterized in that a biasing means is provided at the end of the shaft of the nozzle vane to constantly bring the axial end surface of the engaging portion of the nozzle vane into contact with the axial end surface of the engaging portion of the hollow metal shaft. Turbocharger nozzle vane support structure.