Power controlling device for four-wheel drive vehicle

#The present invention relates to a power control device for a four-wheel drive vehicle, and more particularly, to a power control device for a four-wheel drive vehicle capable of providing a stable drive mode.

#In general, a four-wheel drive vehicle with a part-time four-wheel drive system includes a propeller shaft, a differential, a drive shaft, and so forth, so as to transfer a driving power to the front wheels only according to the selection of the driver. FIG. 1 is a cross sectional view illustrating a conventional front-wheel transmission of such a four-wheel drive vehicle. The power transmitted through a transfer 10 drives a pinion gear engaged to a transmission shaft 20, and then is transmitted to left and right wheel drive shafts 50a and 50b through a ring gear meshed with the pinion gear.

#If the four-wheel drive vehicle is driven by only rear-wheel drive, the rotating force transmitted from front wheels causes the transmission shaft 20, the pinion gear, ring gear and wheel drive shafts 50a and 50b to be idled, thereby increasing gear noise and thus lowering fuel economy.

#The accompanying drawings, which are included to provide a further understanding of the present invention and are incorporated in and constitute a part of this application, illustrate embodiment of the present invention and together with the description serve to explain the principles of the present invention. In the drawings:

#FIG. 1 is a cross sectional view illustrating the construction of a conventional front-wheel transmission for use in a four-wheel drive vehicle;

#FIG. 2 is a cross sectional view illustrating the construction of a conventional power controlling device operating an actuator by use of a vacuum pressure of an engine;

#Referring to FIG. 3, a differential clutch gear 110 and a connecting shaft clutching gear 120 are installed to one side of a differential case. In order to interrupt the connection between the differential clutch gear 110 and the connecting shaft clutching gear 120, the present invention preferably includes an electromagnet 200, and a shift rod 210 operated by a magnetic field generated by the electromagnet 200. A fork 220 is formed on one side thereof for operating the differential clutch gear 110. A return spring 230 constantly biases the shift rod toward its original position.

#As shown in FIG. 4, the electromagnet 200 is connected to a drive shifting switch 201 preferably provided in the cabin of the vehicle, and is connected to a terminal B+ of a battery of the vehicle. If the drive shifting switch 201 is shifted to select four-wheel drive mode, a four-wheel drive terminal 201a is connected to an output terminal 201c, so that the electromagnet 200 is energized to form a magnetic field. If the drive shifting switch 201 is shifted to select two-wheel drive mode, a two-wheel drive terminal 201b is connected to the output terminal 201c, so that the electromagnet 200 is deenergized.

#The electromagnet preferably may employ a common iron core, but as an alternative an electromagnet employing a superconductor having a high critical magnetic field may be used.