JPS6143923Y2 - - Google Patents

Description

[Detailed description of the invention] This invention is particularly effective when using ceramic parts in combination with regular metallic parts in turbochargers that rotate at high speeds under high temperatures. The present invention relates to an impeller support device for a turbocharger that is fastened to a ceramic shaft.

Ceramic materials are superior to metallic materials in terms of high-temperature strength, thermal shock resistance, low thermal conductivity, and low coefficient of thermal expansion, so they can be used as components of turbochargers that rotate at high speeds at high temperatures. It is lower cost, more heat resistant, and lighter than conventional products, making it possible to obtain a supercharger with excellent responsiveness to engine loads. However, ceramic materials are susceptible to mechanical shock, so when considering the structure of the joints when used in combination with dissimilar parts, such as the structure of the fastening part between a metallic impeller and a ceramic shaft that supports the impeller, it is necessary to use thread cutting or press-fitting. There are also processing problems that arise from the difficulty of forming metallic parts, strength problems where the required strength cannot be obtained with parts of the same shape as metallic parts, and thermal deformation that causes looseness or cracking of closely bonded parts at high temperatures. There are many problems, and unless all these problems are solved, it will be difficult to combine ceramic parts with metal parts to construct a machine.

Figure 1 shows the structure of a conventional metal impeller a that is fastened to a metal shaft b. Impeller a is fastened to shaft b using a nut d that engages with a screw c provided on shaft b. Although it has been
If the shaft b is made of ceramic material, thread cutting is quite difficult, and even if thread cutting is performed, the strength of the thread is insufficient, so it is difficult to adopt the structure shown in the drawing.

This invention was devised to solve the above-mentioned problem and provide a support device that easily fastens the impeller of a turbocharger to a ceramic shaft. The shaft is provided with a fixed two-piece turret structure and a nut having a tapered part that engages with a tapered part provided on the outside of the cotter, and a mechanism that presses the nut against the tapered part of the cotter. By configuring the impeller inserted in the turbocharger to be tightened on the side opposite to the rotor, the impeller of the turbocharger can be safely and securely tightened to the shaft, and is superior to conventional models in terms of manufacturing costs and heat resistance. It is possible to provide a turbo supercharger.

Embodiments of the present invention will be described below with reference to the drawings.

2 and 3 show a first embodiment of the present invention, in which a groove 2 having a square cross section is recessed in the shape of a ring on the outer circumference of the shaft near the shaft end of a shaft 1 made of ceramic. Two-piece rotors 5, 5 having a conical tapered portion 4 that converges in the direction of the aluminum alloy impeller 3 are fixed in the grooves so as not to be movable in the shaft direction. A male thread 6 is carved on the outer periphery of the end of the impeller 3, and a nut 9 having an internal thread 7 and a tapered part 8 that engage with the male thread 6 and the taper part 4 of the cotter, respectively, is inserted between the cotter 5 and the impeller 3. It is provided in

Next, the operation of this device will be explained.

When the nut 9 is rotated in a predetermined direction, the screws 6 and 7
Due to this action, the nut 9 moves in the direction of the arrow f and is pressed against the tapered portion 4 of the rotor 5. When the nut 9 is further rotated, the nut 9 and the screwdriver 5 are tightly fitted, and the nut 9 no longer moves in the f direction, and this time the impeller 3 is pressed in the direction of the arrow g, and the impeller 3 is moved to the shaft step (not shown). Press it against the area and tighten firmly.

Since the ceramic shaft 1 is not provided with a threaded portion as seen in conventional support devices, the impeller 3 is securely and securely fastened to the shaft 1. It is advantageous if the directions of the screws 6 and 7 are set in the opposite direction to the rotational direction of the impeller 3, since the greater the torque applied to the impeller, the greater the tightening force of the nut 9, allowing for more secure tightening. .

A second embodiment is shown in FIG. In this example, the first
The male and female screws in the embodiment are oppositely provided, and the nut 9 is slidably supported on the outer periphery of the shaft 1, which has the advantage that the nut 9 can be operated reliably.

A third embodiment is shown in FIG. In this example, a spring 12 is provided between the opposing end faces 10 and 11 of the impeller 3 and the nut 9, and other than the above, there is no difference from the previous embodiment. This device is advantageous in that since the impeller 3 is fastened by the repulsive force of the spring 12, there is no risk of the fastening force being reduced due to loosening of the screw in the above example.

FIG. 6 shows a modification of each of the embodiments described above, in which a groove 13 with an arcuate cross section is provided instead of a groove with a square cross section. This device is advantageous in that stress concentrations do not occur in the groove area.

Note that the present invention is not limited to the above-described embodiments, and it goes without saying that various changes can be made without departing from the gist of the present invention.

The impeller support device for a turbocharger of the present invention can safely and reliably fasten an impeller to a ceramic shaft with a simple structure without providing screws on the ceramic shaft, and therefore takes advantage of the advantageous properties of ceramic material. It demonstrates excellent effects such as providing a turbo supercharger that takes full advantage of the engine.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the impeller support structure of a conventional turbocharger, Figs. 2 and 3 show the first embodiment of the present invention, Fig. 2 is a cut side view, and Fig.
The figure is a cutaway front view taken from the − direction in FIG. 2, FIG. 4 is a cutaway side view showing the second embodiment, FIG. 5 is a cutaway side view showing the third embodiment, and FIG. FIG. 7 is a cutaway side view showing a modification of the first to third embodiments. In the figure, 1 is a shaft, 2 and 13 are grooves, 4 and 8 are tapered parts, 5 and 5 are screws, 6 and 7 are screws, and 9
indicates a nut, and 12 indicates a spring.

Claims (1)

[Scope of utility model registration request] A cotter with a two-piece structure that is immovably engaged with a recess provided on the outer periphery of a ceramic shaft, and a nut having a tapered part that engages with a tapered part provided on the outside of the cotter, the nut being 1. An impeller support device for a turbo supercharger, characterized in that the impeller inserted into the shaft is tightened in a direction opposite to the impeller via a mechanism that presses against a tapered portion of the impeller.