Field of Invention

[001] The present invention relates to the thermal conditioning of a rotating electrical machine and more particularly, it deals with the cooling fan and its airflow arrangement with the front and rear support of the machine.

Background of the invention

[002] In most of the available electrical machine particularly for an automobile alternator a centrifugal fan is used, in the study it is found that the air circulation is limited also the cooling performance is moderate. To increase the air flow and to achieve better cooling performance the present invention proposes the axial fan to produce air flow of axial-in and radial-out concept, which rooms within a duct of the front/rear support of the machine. The duct in the outer circumference of the fan provides a suction head.

[003] Also the axial fan without a suction duct produces lesser cooling performance comparatively.

[004] The simulation study of comparison between the conventional centrifugal fan and the axial fan within the duct is tabulated below: [005] The above study results in increase in air flow rate and decrease in the machine temperatures in every part.

Objective of the invention

[006] The main objective of the invention is to increase the airflow rate within the machine

[007] Another objective of the invention is to decrease the machine temperature

[008] Other objectives of the invention are appended within the detailed description of the invention.

Summary of the Invention

[009] The electrical machine for an automobile application contains a rotor, a stator, a stator housing, a front and a rear support. A cooling fan is provided at any one or both of the axial ends to circulate air within the machine and to reduce the machine temperature.

[010] Preferably for a better air circulation at least one of the front or rear support comprises at least one duct in the same radial plane of the cooling fan in the machine.

[Oil] Preferably, the said cooling fan parallel within the duct is fixed to the shaft for an integral rotation with the machine

[012] Preferably, the radial ring strip duct is an integral mold with the bracket.

[013] Preferably, the cooling fan is an axial type blower. [014] Preferably, the axial height of the duct is larger than the axial height of the fan.

[015] Preferably, the fan is fixed with the shaft using a spline and a spacer.

[016] Preferably, the shaft is characterized with a spline to mount the fan mounting spacer.

[017] Preferably, the spacer is the element to connect fan with the spline in the rotor shaft.

[018] Preferably, the spacer contains two axial parts and the fan is fixed between the said two axial parts.

[019] Preferably, the duct and the radially aligned fan is either external to the ribs or internal within the ribs of the front/rear support.

[020] Preferably, the fan base plate is at the center and the blades are extending radially from the base.

Brief Description of Drawings

[021] Figure 1 shows the bracket with external ring strip (duct)

[022] Figure 2 represents the cooling fan within the external ring strip (duct)

[023] Figure 3 represents the shaft with cooling fan mountings for integral rotation

[024] Figure 4 shows the bracket with internal ring strip (duct)

[025] Figure 5 represents the cooling fan within the internal ring strip (duct) [026] Figure 6 is the rotating electrical machine with front and rear ducted bracket.

Brief Description of the preferred embodiments

[027] Figure 6 shows an electrical machine particularly an alternator for an automobile application. As shown in figure 6 it contains a rotor (17) with a shaft (9) in its central axis. A stator (18) circumferentially spreads around the rotor (17). A front bearing (16) and a rear bearing (20) mounted on the shaft is used to assemble the stator (18), front bracket (22) and a rear bracket (23) with the machine. A pulley (15) is attached with the shaft to drive the machine. A inverter assembly (24) is inbuilt with the machine as shown in the figure.

[028] Figure 1 & 2 shows one of the embodiment of the present invention. From figure 1 the front and/or the rear support of the present invention is equipped with a ring strip herein after referred to be a duct

(2). The said duct is in the radial end of the bracket or the support externally to the ribs (3). It also contains ventilation openings (4), ribs

(3) and flanges (5) to connect the stator housing with the bracket.

[029] From figure 2 the front and/or the rear support of the present invention equipped with a ring strip circumferentially parallel to the cooling fan (7).

[030] Figure 3 shows the axial fan (7) mounted on the rotor shaft (9). In the mounting assembly, a spline (10) in the shaft and a spacer (11) is used to mount the cooling fan (7). [031] Figure 4 & 5 shows another embodiment of the present invention. Here the duct (2) is delimited in the bracket or the support (22) (23) within the ribs (3).

[032] Figure 5 is the front (22) and/or the rear support (23) of the present invention equipped with a ring strip circumferentially parallel to the cooling fan (7).

[033] The invention of axial fan (7) (19) concept within the duct (2) is not limited to the discussed embodiments.

[034] As shown in figure 2 or 5 a radial duct (2) made of ring strip is introduced circumferentially parallel to the axial fan (7). The said duct is in external to the ribs (3) or within the ribs (3) of the front (22) or the rear support (23) of the machine.

[035] The present invention particularly discusses on a front (22) or rear support (23) contains a duct (2) in the same radial plane of the axial fan (7) (19).

[036] The axial fan (7) is mounted to the rotor shaft (9) exactly to engage in parallel within the duct. The axial fan (7) is in integral rotation with the rotor shaft (9).

[037] To engage fan (7) within parallel to the duct (2) the shaft is characterized with a spline (10) arrangement. A spacer (11) is able connect the fan blades with the spline (10). The spacer (11) contains two axial parts and the fan is fixed between the said two axial parts.

[038] The duct (2) is the reference for the position of the axial fan (7) to engage exactly parallel within the duct. In other words the duct (2) is radially aligned with the axial fan (7). The axial height of the duct is larger than the axial height of the fan. The fan (7) and the radially aligned duct (2) are in either external (6) to the ribs or internally (13) within the ribs of the front/rear support.

[039] The fan (7) has the base plate at the center and the blades are extending radially from the base.

[040] The fan (7) produces airflow in an axial-in and radial-out concept. In an axial-in of airflow, the duct (2) provides a suction head to enhance the air suction. A large air injection is possible with the presence of duct (2) compared to the air flow without a duct.

[041] The large air injection enhances the cooling efficiency of the machine largely.