Brushless automotive alternator having improved structure for minimizing temperature of auxiliary rectifying elements

Abstract

According to the present invention, a brushless alternator includes a stationary field winding, a rotor with a rotary shaft, a bearing rotatably supporting an end portion of the rotary shaft, a stator, a protective cover, and a rectifier covered by the protective cover. The rectifier includes a plurality of main rectifying elements for providing a DC output of the alternator, a heat sink having the main rectifying elements provided thereon and working to dissipate heat generated by the main rectifying elements, and a plurality of auxiliary rectifying elements for supplying DC field current to the field winding. The auxiliary rectifying elements are arranged in an axial space between the bearing and the protective cover and kept away from the heat sink. With such an arrangement, it is possible to minimize heat transfer from the heat sink to the auxiliary rectifying elements, thereby minimizing the temperature of the auxiliary rectifying elements.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be understood more fully from the detailed description given hereinafter and from the accompanying drawings of the preferred embodiment of the invention, which, however, should not be taken to limit the invention to the specific embodiment but are for the purpose of explanation and understanding only.

In the accompanying drawings:

FIG. 1 is a partially cross-sectional view showing the overall configuration of a brushless automotive alternator according to an embodiment of the invention;

FIG. 2 is a rear end view of the brushless automotive alternator omitting the majority of a rear cover of the alternator;

FIG. 3 is a rear end view of a rectifier of the brushless automotive alternator;

FIG. 4 is a front end view of the rectifier;

FIG. 5 is a perspective view of the rectifier;

FIG. 6 is a partially cross-sectional view showing part of the rectifier and the rear cover in assembled state; and

FIG. 7 is a graphical representation giving comparison in temperatures of auxiliary diodes and a bearing between the brushless automotive alternator according to the embodiment of the invention and a conventional brushless automotive alternator.

Claims

1. A brushless alternator comprising: a stationary field winding working to create a magnetic flux;a rotor having a rotary shaft and working to create a rotating magnetic field with the magnetic flux created by the field winding;a bearing rotatably supporting an end portion of the rotary shaft;a stator working to generate an AC power in the rotating magnetic field created by the rotor;a protective cover; anda rectifier covered by the protective cover, the rectifier including a plurality of main rectifying elements, a heat sink, and a plurality of auxiliary rectifying elements, the main rectifying elements working to rectify the AC power generated by the stator to a first DC power that is to be output from the alternator to external, the heat sink having the main rectifying elements provided thereon and working to dissipate heat generated by operation of the main rectifying elements, the auxiliary rectifying elements working to rectify the AC power generated by the stator to a second DC power that is to be used to energize the field winding, the auxiliary rectifying elements being arranged in an axial space between the bearing and the protective cover and kept away from the heat sink, so as to minimize heat transfer from the heat sink to the auxiliary rectifying elements.

2. The brushless alternator as set forth in claim 1, wherein the heat sink is arranged outside the auxiliary rectifying elements in a radial direction of the rotary shaft and away from the auxiliary rectifying elements in an axial direction of the rotary shaft.

3. The brushless alternator as set forth in claim 1, wherein the auxiliary rectifying elements are so arranged as not to align with each other in an axial direction of the rotary shaft.

4. The brushless alternator as set forth in claim 1, wherein the protective cover has an air intake hole formed therethrough which is in alignment with one of the auxiliary rectifying elements in an axial direction of the rotary shaft.

5. The brushless alternator as set forth in claim 1, further comprising a barrier for blocking heat transfer from the heat sink to the auxiliary rectifying elements.

6. The brushless alternator as set forth in claim 5, wherein the rectifier further includes a terminal block that includes a plurality of terminals for making electrical connection to the main and auxiliary rectifying elements and a retention portion for retaining the auxiliary rectifying elements, and wherein the retention portion has a concave shape with a bottom surface, on which the auxiliary rectifying elements are arranged, and a side wall that serves as the barrier to block heat transfer from the heat sink to the auxiliary rectifying elements.

7. The brushless alternator as set forth in claim 1, wherein the protective cover has an air guide wall formed therein for guiding cooling air from outside of the alternator to the auxiliary rectifying elements.

8. The brushless alternator as set forth in claim 1, wherein the brushless alternator is designed for use in a motor vehicle.