Powered, folding ramp for minivan
View Patent ↗A drive mechanism under the floor of a minivan is coupled to the folding ramp by a rotating arm linkage, also located beneath the floor. The extension of the folding ramp is partially controlled by dynamic braking, i.e. using the electric motor as a generator and coupling the motor to an electrical load.
1. A minivan adapted for wheelchair access by a folding ramp having one end attached to the minivan by a hinge and by a drive mechanism including an electric motor having a rotor shaft coupled to said folding ramp for raising or lowering the ramp by rotating the folding ramp about said hinge, characterized in that:
said drive mechanism is located beneath the floor of the minivan;
said rotor shaft is substantially parallel with said hinge and includes a pair of arms coupled to said rotor shaft;
said ramp includes a pair of brackets;
said drive mechanism includes a pair of shafts extending underneath said hinge and coupling the arms to the brackets, whereby rotation of the rotor shaft causes rotation of the ramp about said hinge.
2. The minivan as set forth in claim 1 wherein said drive mechanism includes:
a reduction gear having an input coupled to the rotor shaft and having an output shaft;
a drive shaft coupled to said output shaft.
3. The minivan as set forth in claim 2 wherein said drive shaft is supported by at least two sets of bearings.
4. The minivan as set forth in claim 2 and further including a position sensing switch coupled to said drive shaft for interrupting power to said electric motor at a predetermined position of said ramp when the ramp is being extended.
5. The minivan as set forth in claim 4 , wherein said drive shaft can drive said motor and further including
a heat dissipating load;
a braking switch for switching current from said motor to said heat dissipating load, thereby dynamically braking the folding ramp during extension.
6. The minivan as set forth in claim 2 , wherein said drive shaft can drive said motor and further including
a heat dissipating load;
a braking switch for switching current from said motor to said heat dissipating load, thereby dynamically braking the folding ramp.
7. The minivan as set forth in claim 6 wherein said load brakes the fall of the ramp while the ramp is extended without applying power to said motor.
8. The minivan as set forth in claim 7 wherein said load includes a resistor for dissipating current generated by said motor.
9. The minivan as set forth in claim 8 and further including a diode in series with said resistor for blocking current through said resistor when said ramp is raised and the motor is driven in the opposite direction from when the ramp is lowered.