JPH10206447A - Magnetic detected body of rotary detecting mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a rotor to be attached without losing the balance and prevent the generation of noises by magnetizing a nut screwed on the end of a rotary shaft of the rotor to constitute a magnetic detected body. SOLUTION: A rotation detecting mechanism 30 provided in a turbo charger magnetizes a fixing nut 14 for fixing an impeller of of a compressor to provide a fixed and magnetized nut 31 as a detected body. Also, a detecting coil 32 is disposed in a position corresponding to the fixed and magnetized nut 31 outside an air intake port 21 of a housing 20. When a rotor 10 of a turbo charger is rotated, the fixed and magnetized nut 31 is rotated and a magnetic field generated thereby cross the detecting coil 32 so that electric current is generated in the detecting coil 32 by electromagnetic induction. This electric current provides sine wave alternating current, since the fixed and magnetized nut 31 is polarized circumferentially. Thus, the rotational frequency of the rotor 10 can be detected by counting the frequency and since the fixing nut 14 constitutes a magnetic detected body, the rotor 10 can be attached without losing the balance and the generation of noises can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic detection object provided on a rotating body for detecting the rotation of a high-speed rotating body such as a rotor of a turbocharger and measuring the number of rotations.

[0002]

2. Description of the Related Art In the performance test of a mechanism having a rotating body, such as a turbocharger used for an automobile or marine engine, it is necessary to accurately measure the number of revolutions of the rotating body.

[0003] The number of rotations of the rotating body is measured by detecting the rotation of the rotating body with a detecting mechanism and measuring it.
In the case of a high-speed rotating body that cannot detect rotation by contact or an optical method, such as the above-described rotor of a turbocharger, there is one that detects rotation using magnetism.

[0004] The rotation detecting structure of a rotating body using magnetism is
As shown in FIG. 5, a detection object a having a rod-shaped magnet b embedded in a radial direction thereof and a fall prevention ring c fitted on the outer periphery is fixed to an end of a rotation axis d of the rotating body. Although not shown, a detection coil as detection means is provided at a predetermined position around the detection object installation area. As a result, the magnet b of the detection target a rotates due to the rotation of the rotating body, and the magnetic field crosses the detection coil, and a sine wave current is generated in the detection coil by electromagnetic induction. The number of rotations can be known.

[0005]

However, in the above-described rotation detecting structure, since the detection object in which the magnet is embedded is fixed to the end of the rotation shaft of the rotation body, imbalance occurs in the rotation body. However, there is a problem that vibrations during rotation are caused and the strength of the bearing and the rotating shaft is affected.

[0006] In addition, there is another problem that when the detection target member is mounted on the high-speed rotating part, a wind noise is generated, which causes noise.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a magnetic detection object of a rotation detection mechanism which can be mounted without losing the balance of a rotating body and does not generate noise. Aim.

[0008]

According to a first aspect of the present invention, there is provided a rotation detecting mechanism for detecting a magnetic force of a magnetic detecting object provided at an end of a rotating body such as a rotor of a turbocharger. In a rotation detecting mechanism for detecting rotation of the rotating body by detecting by a detecting means disposed around the rotating body, the magnetic sensing object is a compressor screwed to an end of a rotating shaft of the rotating body. A nut, such as a fixed nut of the impeller, is characterized by being magnetized.

[0009]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a partial cross-sectional perspective view of a turbocharger for an automobile equipped with one configuration example of a magnetic detection object of a rotation detection mechanism according to the present invention, and FIG. 2 is a cross-sectional view of a compressor side thereof.

The illustrated turbocharger 1 is configured such that a rotor 10 is rotatably provided in a housing 20 via a rotating shaft 11 thereof.

The rotor 10 has a compressor impeller 12 and a turbine impeller 13 fitted to the end of a rotating shaft 11 and is fixed by a fixing nut 14 screwed to a threaded portion 11A at the shaft end of the rotating shaft 11.

A rotation detecting mechanism 30 is provided on the compressor side (compressor impeller 12 side) of the turbocharger 1.

In the rotation detecting mechanism 30, the fixed nut 14 for fixing the compressor impeller 12 is used as a fixed magnetized nut 31 as a magnetic detection object, and the fixed magnetized nut 31 outside the air intake port 21 of the housing 20 is connected to the fixed nut 14. The detection coil 32 is provided at a corresponding position.

As shown in the side view of FIG. 3A and the plan view of FIG. 3B, the fixed magnetized nut 31 is a hexagonal nut and is formed of a magnetizable material such as magnet steel. It is polarized in the circumferential direction to form a permanent magnet.

The detection coil 32 is formed by winding an enamel wire, and is provided outside the housing 21 with the center axis of the detection coil 32 perpendicular to the rotating shaft 11 of the turbocharger 1 (radial direction of the compressor impeller 12). .

The rotation detecting mechanism 30 constructed as described above
Then, when the rotor 10 of the turbocharger 1 rotates, the fixed magnetization nut 31 rotates accordingly, and the magnetic field generated by the fixed magnetization nut 31
And a current is generated in the detection coil 32 by electromagnetic induction. Since the fixed magnetized nut 31 is polarized in the circumferential direction, the current flowing through the detection coil 32 is a sine wave alternating current. Therefore, by counting this frequency, the rotation speed of the rotor 10 can be detected. .

As described above, in the configuration of the present invention, the fixed nut 14 for fixing the compressor impeller 11 is a fixed magnetized nut 31 and has the function of a magnetic sensing object. (Rotor 10)
Therefore, it is not necessary to provide the magnetic object, so that the cost can be reduced, and the rotor 10 is not unbalanced by newly mounting the magnetic sensing object.
Further, noise such as wind noise does not occur.

The permanent magnetized nut 31 is made permanent magnet as in the above-described configuration. In addition to the magnetized steel, the nut is formed as shown in FIGS. 4A and 4B. Is formed by embedding a permanent magnet 33 such as a ferrite magnet in the space 31A. The permanent magnet can be magnetized (magnetized) after embedding a molded and magnetized one, or filling a space 31A with a ferrite material and firing. The tightening side of the space 31A may be either closed as shown in FIG. 7A or not necessarily closed as shown in FIG.

[0019]

As described above, according to the magnetic object of the rotation detecting mechanism according to the present invention, the nut screwed to the rotating shaft is magnetized and has the function of the magnetic object. There is no need to attach a new separate magnetic sensing object to the rotating shaft, thus reducing costs and generating noise such as unbalanced rotors and wind noise caused by installing the new magnetic sensing object. There is no one.

[Brief description of the drawings]

FIG. 1 is a perspective view, partly in section, of a turbocharger for an automobile equipped with a configuration example of a magnetic detection object of a rotation detection mechanism according to the present invention.

FIG. 2 is a sectional view on the compressor side of FIG. 1;

FIG. 3A is a side view of a fixed magnetization nut, and FIG. 3B is a plan view.

FIGS. 4A and 4B are cross-sectional views showing a magnetization structure of a fixed magnetization nut.

FIG. 5 is an exploded view of a detection target as a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Turbocharger 10 Rotor (rotating body) 11 Rotary shaft 12 Compressor impeller 14 Fixed nut 30 Rotation detecting mechanism 31 Fixed magnetized nut

Claims (2)

[Claims] 1. A rotation detecting mechanism for detecting rotation of the rotating body by detecting magnetism of a magnetic sensing body provided at an end of the rotating body by detecting means disposed around the magnetic sensing body. The magnetic detection object of the rotation detection mechanism, wherein the magnetic detection object is configured by magnetizing a nut screwed to an end of a rotation shaft of the rotating body. 2. The magnetic sensing object according to claim 1, wherein the rotating body is a rotor of a turbocharger, and the nut is a fixed nut of a compressor impeller.