The present invention relates to an ac generator driven by, for example, an internal combustion engine, in particular, to a stator construction of the ac generator loaded in a vehicle such as a passenger car, a truck or the like.
In an ac generator for a vehicle, requirement for downsizing and high-powering, or for an enhanced insulation performance and an electrolytic corrosion tolerance have been recently increasing, and a variety of improved approaches to fulfill those requirements have been proposed.
With respect to an improvement of a power generation capacity, as described in JP H11-164505, an improved construction in which each of the electrical conductors is separately disposed in space one another and a thickness in insulating layers in a cross-over portion of electric conductors is set smaller than that in a slot-in portion located in slots, has been proposed in order to improve cooling capabilities in the cross-over portion of the conductors and obtain higher output and efficiency of the generator.
In the conventional stator, generally, it was well known that electric conductors coated with insulator films have been widely used, and the insulator films cause thermal dissipation of the conductors to seriously suppress to low levels. However, it is practically impossible for the insulator films to be removed or made smaller in thickness because the insulation capability of the conductors will be unallowably weakened.
The present invention has been made in order to solve the above-described problem, and it is an object thereof to obtain an ac generator for a vehicle which can ensure insulation capability between coils and can achieve downsizing and high-powering or improvement in the insulating capacity and electrolytic corrosion resistibility without a necessity of separately disposing each conductor in space.
The present invention is characterized in that an ac generator for a vehicle is provided with a rotor having field windings, a stator including a stator core placed facing to the rotor and an electrical conductor wound on the stator core, and a housing supporting the rotor and the stator, wherein the stator core is constituted by a laminated core having a plurality of slots each extending to an axial direction, the electrical conductor is comprised of a slot-in portions located in the slots and a cross-over portion connecting the slot-in portions each other at the shaft end side of the stator core, wherein the shape of conductors in the slot-in portions located in the slots is substantially rectangular in its cross section and the shape of conductors in the cross-over portion is substantially circular in its cross section, and at least a longer side out of the conductors in the slot-in portions located in the slots is smaller in thickness of their insulation layers than that of insulation layers in the cross-over portions.
According to the present invention, as an ac generator for a vehicle is constituted so that the shape of conductors in the slot-in portions located in the slot is substantially rectangular in its cross section and the thickness in insulation layers of that portions is smaller than the other portion, there are advantages that heating from the conductors can be efficiently conducted to the laminated core and the housing.
On the contrary, the thickness in insulating layers of the cross-over portions is larger than the other, insulation capability among the coils is assured and the axial height of the cross-over portion can be lowered to prevent conductors of the cross-over portion from water immersion, improving electrolytic corrosion resistibility without disposing unnecessary space among coils.
An ac generator for a vehicle of a first embodiment of the invention will be described referring to
In
Where the slot-in portion 44a is constructed so that the longer side of a substantially rectangular shape in the cross section is larger in length than a gap 41e (slot opening) between collars 41d to prevent the conductor 44 from dropping out of the slot.
A slot opening-pass portion 44d following the slot-in portions 44a is formed in flattened shape in cross section and a longitudinal axis thereof is in a direction perpendicular to the longer side of a substantially rectangular shape in cross section and a length of a short axis thereof is smaller than the gap 41e between the collars 41d (see
According to the aforementioned embodiment of this invention, since the slot-in portions 44a of the conductor 44 are accumulated in slots 41c in the radial direction without any air space, it is possible to raise densities of electrical conductors in the slot-in portion and conductivities of heat from electrical conductors to the laminated core or the housing. In order to realize such a conductor rod, an insulation coating conductor with round shape in cross section is molded to substantially rectangular shape in cross section by a mill roll and the like before it is entered in slots 41c. For example, when the insulating coating conductor with round shape in cross section of 1.6 mm in diameter is rolled by the mill roll into one direction to 1.3 mm thickness flattened, the insulating coating on a surface rolled, that is a flattened insulating coating is extended thinly, but the insulating coating on a surface not rolled, that is a circular curved insulating coating keeps unchanged in the thickness, causing the flattened insulating coating to be thinner than the circular curved insulating coating. For example, in the case of the insulating coating conductor with round shape in cross section of approximately 50 μm in the thickness of enamel system insulating coating, it is possible to obtain a running track-like conductor in cross section having an approximately 50 μm thick of circular curved insulating coating and 40 μm thick of flattened insulating coating. Namely, as the thickness of the insulating coating becomes thin in the radial direction, the amount of heat generated by armature windings is effectively dissipated to the periphery of the laminated core positioned in the radial direction and promotion of output power and efficiency of the generator are achieved by synergistic effect of improvement in lamination factor in slots and heat conductivity.
In addition, according to this embodiment, as shown in
Therefore, because thickness of insulating coating in the cross-over portion 44b remains unchanged, that is, can maintain enough thickness, it is possible to obtain an excellent isolation between coils without providing unnecessary air space between coils, and, because the axial height of the cross-over portion 44b can be lowered, it is also possible to shorten the length of the electrical conductors, resulting in improvement of the output power and efficiency of generator and promoting downsizing. While the vehicle is moving, furthermore, salt water or muddy water could submerge through the exhaust holes 37, 39, however since thickness of insulating coating in the cross-over portion 44b is kept in thick according to this invention, it is possible to protect the electrical conductors from immersing and to prevent electric corrosion between each of 3 phases or between coils and the housing.
According to the second preferred embodiment, as shown in
The above mentioned construction enables the slot-in portions 44a of the conductor 44 to be installed in the slot 41c with no space each other circumferentially.
According to the second embodiment, therefore, as the electrical conductors are closely laminated in the radial direction at the longer side of the rectangular rod at which the insulating coating is kept thin in the circumferential direction, it is also possible to improve densities of the electrical conductors in slots 41c and conductivities of heat generated by the electrical conductors to the laminated core or the housing, resulting in further enhancement of the output power and efficiency of the generator.
According to the third preferred embodiment, as shown in
The above mentioned construction enables the slot-in portions 44a of the conductor 44 to be installed in the slot 41c with no space each other circumferentially.
According to the third embodiment, therefore, as a heat conductive surface between the longer side of the rectangular rod at which insulating coating is kept thin in the radial direction and the dents of teeth of the laminated core are kept widely, it is also possible to effectively dissipate heat generated by armature windings to the periphery the laminated core through the dents of teeth of the laminated core, resulting in further enhancement of the output power and efficiency of the generator. By interposing an insulating member between the thin portion of the insulating coating and the dents of teeth of the laminated core, it is possible to improve insulating strength between electrical conductors and cores. Further, when an insulating resin is impregnated in the slot 41c to mold the slot-in portions, it is also possible to effectively dissipate heat generated by armature windings to the periphery of the laminated core in the radial direction, resulting in improvement of insulating strength between electrical conductors and cores.
The fourth preferred embodiment describes an example in which a rotor 27 is provided with a plurality of discharging hole ribs and discharging air holes on the periphery of the bracket, and a plurality of fan blades on the fans provided on the rotor 27.
Referring to
This accelerates radiation of the heat coils and results in further enhancement of the output power and efficiency of the generator.
The above was explained on the side of the front bracket 21, but the same ventilation is applied on the side of the rear bracket 22 as well, that is, by the operation of the fan blades 55 provided on the rear bracket 22, the cooling air drawn in longitudinally from the charging air holes 36 is bent centrifugally after passing through between the charging hole ribs 62 and is exhausted to the outside through the discharging air holes 39 between the discharging ribs 61 after cooling a rear end portion of the stator winding 42.
The fifth preferred embodiment describes an effective method for disposing the slot-in portion 44a of the electrical conductors in the slots 41c. The method known by, for example, Japanese Patent No. 3,400,776 (Patent document 2) in which a manufacturing process for an ac generator for a vehicle is described is used for storing the winding unit molded in substantially rectangular shape in cross section into the slots 41c in this invention closely without any air gap.
As a result, two individual wires 42A, 42B are fit in the core 41A as shown in
According to the method, as the slot portion of the belt-like core is spread in advance to improve the insertion efficiency of the individual wires thereto, it is possible to eliminate the damage of the individual wires when they are inserted to the slots, and to keep the thickness of the insulating materials located in the slots smaller to obtain the extremely high lamination factor.
In addition, it is possible, by rounding the core, to eliminate a gap between the core spread in advance and the electrical conductor and to make closely contact to the insulating materials between them, causing heat generated by the armature windings to efficiently radiate to the periphery of the laminated core via the both sides of the teeth portion.
It is also possible to give the conductors a high electrical insulation capability without giving any damage to the thin insulating coating in the portion forming the flattened surface in cross section of the electrical conductor.
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/JP04/07757 | 5/28/2004 | WO | 12/12/2005 |