Alternator for vehicle

#1. Field of the Invention

#The present invention relates to an alternator for a vehicle, and more particularly to an improvement of a weldment (weld joined portion) at which a terminal of a semiconductor part (e.g., a diode used as a rectifying device) and an electrical connection terminal of a wiring conductor, for example, are connected to each other by welding.

#2. Description of the Related Art

#FIG. 1 is a vertical sectional view showing one embodiment of an alternator for a vehicle in which the present invention is implemented;

#FIG. 2 is a right side view of the alternator of FIG. 1 in a state in which a rear cover is removed;

#FIG. 3 is a sectional view taken along the line A-A in FIG. 2;

#One embodiment of the present invention will be described below in more detail with reference to FIGS. 1, 2, 3 and 4.

#A pulley 2 for transmitting a driving force from an engine (not shown) to a rotor shaft 1 is disposed at an end of the rotor shaft 1, and a rotor 3 having claw-shaped magnetic poles, over which field coils 3a are wound, generates a revolving magnetic field with rotation of the pulley 2. The revolving magnetic field induces an electromotive force in three-phase stator coils 5 wound over respective cores of a stator 4, which is disposed around the rotor 3 with a gap left between them. The rotor shaft 1 is rotatably supported by bearings 6a, 6b, and the bearings 6a, 6b are in turn supported by brackets 7, 8, respectively. The cores of the stator 4 are supported by the bracket 8. The bracket 8 is provided with a water passage 8a through which cooling water is circulated to cool heat generating parts such as the stator coils 5. Gaskets 9a, 9b for sealing off the water passage 8a are disposed respectively at opposite ends of the water passage 8a. The gasket 9b is fixed together with a plate member 10 and a rear cover 11 in a sandwiched relation to the bracket 8 using bolts 12. A brush holder 14 for accommodating brushes 13a, 13b to supply field currents to the field coils 3a and a rectifier 15 for rectifying three-phase AC power generated in the stator coils 5 are both fixed to the plate member 10 using bolts 16a, 16b and nuts 17. The brushes 13a, 13b supply the field currents to the field coils 3a of the rotor 3 while being held in slide contact with respective current collecting rings 19 by pressing forces of springs 18a, 18b both accommodated in the brush holder 14. The field currents are regulated by a voltage regulator 25 accommodated in a part of the brush holder 14, and the voltage of the field currents is adjusted to a prescribed value. The rectifier 15 comprises a minus-side diode 23 fixed to a heat radiating plate 22, a plus-side diode 21 fixed to a heat radiating plate 20, and a connecting member 24 for connecting respective terminals 21a, 23a of the plus-side diode 21 and the minus-side diode 23 to each other. The connecting member 24 comprises a terminal member 24a and an insulating member 24b in which the terminal members 24a are partly embedded. The three-phase stator coils 5 are interconnected in the form of Δ- or Y-connection, and three or four leads 5a from the stator coils 5 are each connected to a terminal portion 24c as a part of the terminal member 24a of the connecting member 24 of the rectifier 15. The terminal 21a, 23a of the plus-side diode 21 or the minus-side diode 23 of the rectifier 15 is connected to another terminal portion 24d of the terminal member 24a, which is positioned oppositely away from the terminal portion 24c, and an AC current flows through the terminal member 24a. Because the terminal member 24a generates heat upon the current flowing through it, a material having small electrical resistance, e.g., copper, is selected as the terminal member 24a of an alternator for a large power. Also, because the terminal portion 24c of the terminal member 24a and the terminals 21a, 23a of the plus-side diode 21 and the minus-side diode 23 are both made of copper, resistance welding has a difficulty in connecting them to each other, and TIG welding is used for connection therebetween. The use of TIG welding requires dimensional accuracy of each terminal and a welding electrode, and a variation occurs in weld penetration (welding depth) depending on the dimensional accuracy. The terminal portion 24d of the terminal member 24a is not uniform in shape and is provided with projected lugs 24e in its intermediate position that is determined in consideration of the welding depth of from the terminal end. The projected lugs 24e have a different heat capacity from the other part of the terminal portion 24d. Accordingly, the projected lugs 24e limit the weld penetration, and even if there are large variations in distance between the welding electrode and each terminal and in dimensions of each terminal, the weld penetration is stopped at the position of the projected lugs 24e and the welding depth is stabilized.

#With this embodiment, since the weld penetration is stably set without being affected by the dimensional accuracy of the terminals, welding can be performed with stability in quality such as welding strength, and severe dimensional management is no longer required. As a result, an alternator can be provided which is relatively inexpensive and easy to manufacture.