This invention relates to an electrically operated seat slide apparatus, and more particularly to the seat slide apparatus having a device for directly transmitting an impact applied to an upper rail to a lower rail without transmitting to a gear box.
Seat slide apparatuses are classified into manually operated seat slide apparatuses and electrically operated seat slide apparatuses. The manually operated seat slide apparatuses are arranged to manually move a seat in a fore-and-aft direction, whereas the electrically operated seat slide apparatuses are arranged to move a seat in a fore-and-aft direction by a rotational force of an electric motor.
One of the electrically operated seat slide apparatuses is disclosed in Japanese Patent Provisional Publication No. 2001-239861. In this electrically operated seat slide apparatus, an upper rail to which a seat is connected is disposed inside a lower rail fixed to a vehicle body. A screw shaft is rotatably disposed inside the upper rail. Two of such a combination of the upper rail, the lower rail and the screw shaft are respectively disposed parallel both on left and right sides. The screw shafts are connected to an electric motor disposed at one of the upper rails so as to be rotationally driven in timed relation to each other. A nut member is threadedly connected to each screw shaft and further connected to the lower rail. Stoppers are connected to each screw shaft at the positions near the opposite ends of the screw shaft by being caulked in order to restrict the movement of the nut member.
In order to allow a high load applied to the upper rail during a collision to be transmitted through the screw shaft to lower rail, two flanges are fixed on the screw shaft and located spaced apart a certain small distance from each other, and a load receiving member is connected to the upper rail and interposed between the two flanges. This load receiving member is fitted in a fitting opening formed in the upper rail and fixed therein by a push-nut or the like.
Japanese Patent Provisional Publication No. 2006-335153 discloses another electrically operated seat slide apparatus in which the upper section of a rail-side stopper is bifurcated to form two stopper plate portions which are respectively fitted in fixation openings of an upper rail and caulked to be fixed in positions.
A further electrically operated seat slide apparatus is disclosed in Japanese Patent Provisional Publication No. 9-123807. In this electrically operated seat slide apparatus, an upper rail to which a seat is connected is disposed inside a lower rail fixed to a vehicle body. A motor is disposed to the upper rail so as to simultaneously rotationally drive two screw shafts which are located respectively on right and left sides of a seat. Two nut members connected to the lower rails are respectively threadedly connected to the right and left side screw shafts. Additionally, two stoppers are connected to each screw shaft at its positions near the opposite ends by caulking the screw shaft, in order to stop a relative movement of the nut member.
Japanese Patent Provisional Publication No. 10-203209 discloses a further electrically operated seat slide apparatus in which a damper is disposed on a lead screw and located on the side of a nut member. The damper is interposed between a damper holding section and a nut member-side plate. When the nut member strikes against the nut member-side plate, the nut member-side plate relatively rotates to the damper so that no torsion is applied to the damper.